                                                                                                                           Opinions of the United
1999 Decisions                                                                                                             States Court of Appeals
                                                                                                                              for the Third Circuit


11-2-1999

In Re: TMI Litigation
Precedential or Non-Precedential:

Docket 96-7623, 96-7624 96-7625




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Recommended Citation
"In Re: TMI Litigation" (1999). 1999 Decisions. Paper 296.
http://digitalcommons.law.villanova.edu/thirdcircuit_1999/296


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Volume 1 of 4

Filed November 2, 1999

UNITED STATES COURT OF APPEALS
FOR THE THIRD CIRCUIT

Nos. 96-7623/7624/7625

IN RE: TMI LITIGATION

LORI DOLAN; JOSEPH GAUGHAN; RONALD
WARD; ESTATE OF PEARL HICKERNELL;
KENNETH PUTT; ESTATE OF ETHELDA HILT;
PAULA OBERCASH; JOLENE PETERSON; ESTATE OF
GARY VILLELLA; ESTATE OF LEO BEAM,

          Appellants No. 96-7623

IN RE: TMI LITIGATION

ALL PLAINTIFFS EXCEPT LORI DOLAN, JOSEPH
GAUGHAN, RONALD WARD, ESTATE OF PEARL
HICKERNELL, KENNETH PUTT, ESTATE OF ETHELDA
HILT, PAULA OBERCASH, JOLENE PETERSON, ESTATE
OF GARY VILLELLA AND ESTATE OF LEO BEAM,

          Appellants No. 96-7624

IN RE: TMI LITIGATION

ALL PLAINTIFFS; ARNOLD LEVIN; LAURENCE
BERMAN; LEE SWARTZ

          Appellants No. 96-7625

ON APPEAL FROM THE UNITED STATES DISTRICT
COURT FOR THE MIDDLE DISTRICT OF PENNSYLVANIA
(Civil No. 88-cv-01452)
(District Judge: Honorable Sylvia H. Rambo)
ARGUED: June 27, 1997

Before: GREENBERG and McKEE, Circuit Judges, and
GREENAWAY, District Judge*

(Opinion filed: November 2, 1999)

          ARNOLD LEVIN, ESQ.
          LAURENCE S. BERMAN, ESQ.
           (Argued)
          CRAIG D. GINSBURG, ESQ.
          Levin, Fishbein, Sedran & Berman
          510 Walnut Street, Suite 500
          Philadelphia, PA 19106

          LEE C. SWARTZ, ESQ.
          Hepford, Swartz & Morgan
          111 North Front Street
          P.O. Box 889
          Harrisburg, PA 17108

          Attorneys for Appellants in
          No. 96-7623/7624/7625

          LOU TARASI, ESQ.
          Tarasi & Johnson, P.C.
          510 Third Avenue
          Pittsburgh, PA 15129

          Of Counsel for Certain Appellants
          Identified in the Entry of Appearance
          in Appeal No. 96-7624/7625
_________________________________________________________________

* The Honorable Joseph A. Greenaway, Jr., United States District Court
Judge for the District of New Jersey, sitting by designation.

                               2
STEPHEN A. SALTZBURG, ESQ.
 (Argued)
Howrey Professor of Trial Advocacy,
Litigation and Professional
 Responsibility
George Washington Law School
720 20th Street, N.W.
Washington, D.C. 20052

Of Counsel for Appellants in
No. 96-7623/7624/7625

DANIEL J. CAPRA, ESQ.
Reed Professor of Law
Fordham University School of Law
Lincoln Center
140 West 62nd Street
New York, NY 10023

Of Counsel for Certain Appellants
Identified in the Entry of Appearance
in Appeal No. 96-7625

A.H. WILCOX, ESQ. (Argued)
ELLEN K. SCOTT, ESQ. (Argued)
ERIC J. ROTHSCHILD, ESQ.
 (Argued)
Pepper, Hamilton & Scheetz, LLP
3000 Two Logan Square
18th and Arch Streets
Philadelphia, PA 19103

LEWIS S. KUNKEL, JR., ESQ.
THOMAS B. SCHMIDT, III, ESQ.
Pepper, Hamilton & Scheetz LLP
200 One Keystone Plaza
North Front & Market Streets
P.O. Box 1181
Harrisburg, PA 17108

Attorneys for Appellees in
Nos. 96-7623/7624/7625

                     3
           REUBEN A. GUTTMAN, ESQ.
           Provost & Umphrey
           1350 New York Avenue, N.W.
           Suite 1040
           Washington, D.C. 20005

           NED MILTENBERG, ESQ.
           Associate General Counsel
           Association of Trial Lawyers of
           America ("ATLA")
           1050 31st Street, N.W.
           Washington, D.C. 20007

           Amicus Curiae, Association of Trial
           Lawyers of America ("ATLA"), in
           Support of Appellants

TABLE OF CONTENTS

I. INTRODUCTION                                      6

II. PROCEDURAL HISTORY                                   8

III. SCIENTIFIC BACKGROUND                           18

 A. Overview of Relevant Principles of
           Nuclear Physics                           18
            1. Atomic and Nuclear Structure          18
  2. Radioactivity                                   24
  3. Ionizing Radiation                              28
  4. Radiation Quantities and Units                  31
  5. Health Effects of Ionizing Radiation            35
   i. Deterministic Effects                          38
   ii. Stochastic Effects                            41
  6. Radiation in the Environment                    44
   i. Natural Radiation                              44
   ii. Man-made Radiation                            49

IV.   NUCLEAR ENGINEERING                            54
 A.   Nuclear Reaction                               54
 B.   The Operation of Nuclear Power Plant           59
 C.   Barriers to Release of Radioactive Materials
             into the Environment                    65

                                 4
V. THE ACCIDENT AND ITS AFTERMATH                    66
 A. The Accident at TMI-2                            66
 B. Radioactive Materials Released to the
           Environment                               70
 C. Pathways of Exposure to Radioactive Materia ls   71

VI. LEGAL DISCUSSION                                 72
 A. The Trial Plaintiffs' Appeal                     72
  1. Background                                      72
  2. Standards Governing the Admissibility of
           Scientific Evidence                       79
  3. Trial Plaintiffs' Dose Exposure Expert
           Witnesses                                 85
   i. Ignaz Vergeiner                                85
    a. Qualifications                                85
    b. Vergeiner's Opinion.                          86
    c. Discussion and Conclusions                    87
   ii. Charles Armentrout and Victor Neuwirth        95
    a. Qualifications                                95
    b. Armentrout's Observations and
           Experiences                               96
    c. Discussion and Conclusion                     98
    d. Neuwirth's Soil Sample Analyses
           and Armentrout's Dose Estimates.           99
    e. Discussion and Conclusion                     101
   iii. James Gunckel                                105
    a. Qualifications                                105
    b. Gunckel's Opinion                             108
    c. Discussion and Conclusions                    112
   iv. Vladimir Shevchenko                           118
    a. Qualifications                                118
    b. Shevchenko's Tree Study                       120
    c. Discussion and Conclusions                    123
    d. The Cytogenetic Analysis                      126
    e. Discussion and Conclusions                    130
   v. Gennady Kozubov                                135
    a. Qualifications                                135
    b. Kozubov's Opinion                             135
    c. Discussion and Conclusions                    137
   vi. Olga Tarasenko                                139
    a. Qualifications                                139
    b. Tarasenko's Opinion                           140

                               5
    c. Discussion and Conclusions                      142
   vii. Bruce Molholt                                  145
    a. Qualifications                                  145
    b. Molholt's Opinions                              146
    c. Discussion and Conclusions                      149
   viii. Sigmund Zakrzewski                            155
    a. Qualifications                                  155
    b. Zakrzewski's Opinion                            158
    c. Discussion and Conclusions                      159
   ix. Theodor Sterling                                161
    a. Qualifications                                  161
    b. Sterling's Opinion                              161
    c. Discussion and Conclusions                      163
   x. Steven Wing                                      166
    a. Qualifications                                  166
    b. Wing's Mortality Study                          166
    c. Discussion and Conclusions                      168
    d. Wing's Cancer Incidence Study                   170
    e. Discussion and Conclusions                      173
   xi. Douglas Crawford-Brown                          173
    a. Qualifications                                  175
    b. Crawford-Brown's Opinion                        175
    c. Discussion and Conclusions                      176
  4. Effect of the Exclusion of Wing's
           Lung Cancer Testimony                       179
  5. Exclusion of Experts' Submissions
           as Untimely                                 181
  6. Conclusion                                        190
 B. The Non-Trial Plaintiffs' Appeal                   191
 C. The Monetary Sanctions Appeal                      200
 D. Reassignment Upon Remand                           201

VII. CONCLUSION                                        203

OPINION OF THE COURT

McKEE, Circuit Judge

I. INTRODUCTION

These three appeals arise out of the nuclear reactor

                               6
accident which occurred on March 28, 1979, at Three Mile
Island in Dauphin County, Pennsylvania.1 Two of the
appeals concern the personal injury claims of more than
2,000 Three Mile Island area residents who allege that they
have developed neoplasms2 as a result of the radiation
released into the environment as a result of the reactor
accident. The first appeal is that of a group of ten trial
plaintiffs who were selected by the parties after the District
Court adopted the plaintiffs' case management order, which
called for a "mini-trial" of the claims of a group of "typical"
plaintiffs (the "Trial Plaintiffs"). The critical issue there is
the trial plaintiffs' ability to demonstrate that they were
exposed to doses of radiation sufficient to cause their
neoplasms. Proof of that causation depended on the
admissibility of the testimony of several experts that the
Trial Plaintiffs retained. These experts attempted to testify
about the amount of radiation released into the
environment by the nuclear reactor accident, and thereby
correlate the plaintiffs' neoplasms to that accident.

Defendants challenged the admissibility of the experts'
testimony and the District Court was therefore required to
hold extensive in limine hearings pursuant to its
"gatekeeping" role under Daubert v. Merrell Dow
Pharmaceuticals, Inc., 509 U.S. 579 (1993). Following those
hearings, the court excluded the overwhelming majority of
the Trial Plaintiffs' proposed expert testimony as to dose
exposure. Following the exclusion of the dose exposure
_________________________________________________________________

1. Sometime prior to argument, the appellees moved to consolidate these
appeals. We denied that request by order dated December 24, 1996. We
did, however, instruct the Clerk to list these three appeals before a
single
merits panel. We now believe that the most expeditious way to dispose
of these appeals is to consolidate them and dispose of them in one
opinion. Therefore, we have entered an order consolidating these three
appeals.

2. A neoplasm is "an abnormal tissue that grows by cellular proliferation
more rapidly than normal and continues to grow after the stimuli that
initiated the new growth cease. N[eoplasm]s show partial or complete
lack of structural organization and functional coordination with the
normal tissue, and usually form a distinct mass of tissue which may be
either benign or malignant." STEDMAN'S MEDICAL DICTIONARY 931 (26th ed.
1995).

                               7
testimony, the defendants moved for summary judgment
alleging that Trial Plaintiffs could not establish causation
absent the excluded expert testimony regarding dose.

The District Court agreed and held that, as a result of its
rulings under Daubert, Trial Plaintiffs were unable to
connect their neoplasms to the TMI accident. Accordingly,
the court granted summary judgment in favor of defendants
and against the Trial Plaintiffs. In re TMI Litigation
Consolidated Proceedings, 927 F. Supp. 834 (M.D. Pa.
1996). The District Court then reasoned that its Daubert
rulings would be binding on all of the other plaintiffs, i.e.,
the Non-Trial Plaintiffs, if there were evidentiary issues
common to all plaintiffs, Id. at 837. Therefore, the court
therefore extended its Trial Plaintiff summary judgment
decision to the Non-Trial Plaintiffs, and granted summary
judgment to the defendants on all of the claims of the
approximately 2,000 remaining TMI personal injury
plaintiffs. The propriety of that extension is the subject of
the second appeal.

The third and last appeal concerns the propriety of the
District Court's imposition of monetary sanctions against
certain of the plaintiffs' counsel for violations of pre-trial
discovery requirements and orders. The sanctioned counsel
have requested that the TMI personal injury litigation be
reassigned to another trial judge upon remand, if we
reverse the District Court in either or both of thefirst two
appeals.

For the reasons that follow, we will affirm the grant of
summary judgment to the defendants on the claims of the
Trial Plaintiffs (No. 96-7623). We will, however, reverse the
grant of summary judgment to the defendants on the
claims of the Non-Trial Plaintiffs (No. 96-7624), but we will
affirm the imposition of monetary sanctions and deny the
request for reassignment (No. 96-7625).

II. PROCEDURAL HISTORY3
_________________________________________________________________

3. The procedural history of this litigation is almost as complicated as
the scientific principles implicated by the Daubert challenges that we
discuss below. However, an understanding of the procedural history is
necessary to our discussion of the District Court's decision to grant
summary judgment against the Non-Trial Plaintiffs as well as the Trial
Plaintiffs.

                               8
On March 28, 1979, radioactive materials were released
into the environment as the result of an accident which
occurred at Unit 2 of the Three Mile Island nuclear power
generating station in Dauphin County ("TMI-2"). Three Mile
Island is a small island in the Susquehanna River,
approximately fifteen miles downstream from Harrisburg,
Pennsylvania. Following the accident, thousands of
personal injury and other non-personal injury claims 4 were
filed against the owners and operators of the nuclear facility.5

As noted, more than 2,000 plaintiffs filed claims for
personal injuries6 purportedly caused by exposure to the
radioactive materials released during the accident. Some of
these personal injury claims were originally filed in the
early 1980's in state and federal district courts in
Pennsylvania, New Jersey and Mississippi. The defendants
removed the state court actions to federal district courts in
Pennsylvania and New Jersey, under the authority of the
Price-Anderson Act, Pub.L. No. 85-256, 71 Stat. 576 (1957).7
_________________________________________________________________

4. The defendants have settled non-personal injury claims brought by
individuals, businesses and non-profit organizations within a twenty-five
mile radius of the TMI facility. See Stibitz v. General Public Utility
Corp.,
746 F.2d 993, 995 n.1 (3d Cir. 1984).

5. The defendants are General Public Utilities, Inc., Metropolitan Edison
Co., Jersey Central Power & Light Co., Pennsylvania Electric Co.,
Babcock & Wilcox, Co., McDermott Inc., Raytheon Constructors, Inc.,
and Burns & Roe Enterprises, Inc. They were, at the time of the
accident, either the owners and operators of the facility or companies
which had provided design, engineering and/or maintenance services to
the owners and operators or vendors of equipment or systems installed
in the facility. In re TMI Litigation Cases Consol. II, 940 F.2d 832, 836
(3d Cir. 1991).

6. The personal injury plaintiffs allege that they have developed
radiation
induced neoplasms because of their exposure to ionizing radiation
resulting from the TMI accident.

7. As we noted in In re TMI Litigation Cases Consolidated II, 940 F.2d
832, 837 n.2 (3d Cir. 1991), the Price-Anderson Act was enacted in 1957
as an amendment to the Atomic Energy Act of 1946, Pub.L. No. 79-585,
60 Stat. 755. The Atomic Energy Act was designed to establish an
industry to generate inexpensive electrical power and it envisioned
turning "atomic power into a source of energy" by turning "swords into
plowshares." Pacific Gas & Electric Co. v. State Energy Resources

                               9
After removal, the District Court for the Middle District of
Pennsylvania ordered, inter alia, that all pending TMI
personal injury cases in the Middle District be
"consolidated for pretrial proceedings only." App. 13097.
The District Court also ordered that the caption of every
subsequent personal injury pleading should be identified as
a personal injury claim. Id.

After we held that the Price-Anderson Act did not create
a cause of action as a federal tort and was not intended to
confer jurisdiction on federal district courts, see Stibitz v.
General Public Utilities Corp., 746 F.2d 993, 997 (3d Cir.
1984) and Kiick v. Metropolitan Edison Co., 784 F.2d 490,
_________________________________________________________________

Conservation & Development Commission, 461 U.S. 190, 193 (1983). The
Atomic Energy Act envisioned the nuclear energy industry as a
government monopoly; however, Congress ultimately decided to permit
the private sector to become involved. See Atomic Energy Act of 1954,
Pub.L. No. 830-703, 68 Stat. 919. The 1954 Act "grew out of Congress'
determination that the national interest would best be served if the
Government encouraged the private sector to become involved in the
development of atomic energy for peaceful purposes under a program of
federal regulation and licensing." Pacific Gas & Electric Co., 461 U.S. at
206-07. Nonetheless, the private sector was wary of the potential
exposure it faced in the event of a nuclear accident because of the
nature of nuclear energy. Thus, while assuring Congress that the risk of
a major nuclear accident was low, "spokesmen for the private sector
informed Congress that they would be forced to withdraw from the field
if their liability were not limited by appropriate legislation." Duke
Power
Co. v. Carolina Environmental Study Group, Inc., 438 U.S. 59, 64 (1978).
In response, Congress enacted the Price-Anderson Act to protect the
public and encourage the development of the atomic energy industry. In
re TMI, 67 F.3d 1103, 1107 (3d Cir. 1995)(citations and internal
quotations omitted), cert. denied, #6D6D 6D# U.S. ___, 116 S. Ct. 1034
(1996).
The Price-Anderson Act limited the "potential civil liability of nuclear
power plant operators and provided federal funds to help pay damages
caused by nuclear accidents." Id. The Act requires nuclear facilities
operators to purchase a specified amount of insurance from private
carriers and further provides for government indemnification above the
insurance amounts to an established aggregate limit on liability. In re
TMI Litigation Cases Consolidated II, 940 F.2d at 837 n.2. The Price-
Anderson Act has been amended three times, most recently in 1988; yet
the goal continues to be "to encourage private sector participation in the
beneficial uses of nuclear materials." Id. at 853.

                               10
493 (3d Cir. 1986), the state court actions were remanded,
and the federal court actions were transferred to the
appropriate state courts. The cases originally removed to
the Middle District of Pennsylvania, and those originally
filed in the Middle District, were either remanded or
transferred to the Court of Common Pleas of Dauphin
County. Thereafter, in 1985 and 1986, the bulk of the
personal injury claims which are the subject of this appeal
were filed in the state courts.8

On October 15, 1985, the Dauphin County Common
Pleas Court entered a case management order. In that
order, the Court of Common Pleas ordered that all cases be
consolidated for pretrial purposes, and also required that
all pleadings be captioned to identify which plaintiffs' group
they applied to. That is, all personal injury cases received
from the federal court were consolidated under the caption
"Cases Consolidated I" and the cases filed in state court
after our decision in Stibitz, were consolidated under the
caption "Cases Consolidated II."

In 1988, Congress enacted the Price-Anderson
Amendments Act of 1988, Pub.L. No. 100-408, 102 Stat.
1066. Those amendments to the Price-Anderson Act created
a federal cause of action for "public liability actions"9 and
provided that all such suits arise under the Price-Anderson
Act, 42 U.S.C. S 2014(h). The Act also provided for
consolidation of such actions, including those already filed,
_________________________________________________________________

8. However, personal injury cases continued to befiled after 1986. The
last case filed that is included in these appeals was Kline, et al. v.
General Public Utilities Corp. et al., No. 1:CV 96-451 (M.D. Pa.), and it
was filed on March 15, 1996. However, the latest personal injury case
filed is Tyler et al v. General Public Utilities Corp. et al., No. 1:CV
96-1028
(M.D. Pa.), and it was filed on June 7, 1996. Brief of Appellants in No.
96-7624, at 6 n.8. Apparently, Tyler is not included in this appeal.

9. The Price-Anderson Amendments Act defined a"public liability action"
as "any suit asserting public liability." 42 U.S.C. S 2014(h). "Public
liability" was defined as "any legal liability arising out of or resulting
from a nuclear incident or precautionary evacuation," except for certain
claims covered by workers' compensation, incurred in wartime or that
involve the licensed property where the nuclear incident occurs. 42
U.S.C. S 2104(w).

                               11
in one federal district court. 42 U.S.C. S 2210(n).10
Following enactment of that Act, the defendants removed all
the pending state actions to the United States District
Court for the Middle District of Pennsylvania.

Thereafter, the District Court for the Middle District of
Pennsylvania conducted a case management conference.
The personal injury cases known as "Cases Consolidated I"
and "Cases Consolidated II" which had been removed from
the Court of Common Pleas of Dauphin County were then
pending in the Middle District along with the companion
actions to the "Cases Consolidated II" which had been filed
by forty-two plaintiffs in Mississippi federal and state court
to take advantage of the more lenient Mississippi statute of
limitations.11 As a result of discussions during the
conference, the District Court entered an order which
required counsel to

          meet to streamline the record with an eye toward
          reducing the number of duplicative plaintiffs and suits,
          assigning fewer case numbers for the various actions,
          and deciding which cases needed new complaints to be
          filed and which actions do not need answers filed.

Supp. App. at 78. In response to the order, counsel for
plaintiffs and defendants submitted a Stipulation which
provided, inter alia, that the pending TMI personal injury
cases referred to as "Cases Consolidated I" and "Cases
Consolidated II," together with the companion Mississippi
cases, would be consolidated under a single civil action
number "for administrative purposes" (emphasis added).
App. Vol. I, at 440. The Stipulation required that pleadings
dealing with issues common to all plaintiffs, or a legal issue
potentially applicable to all plaintiffs, bear the caption "In
re TMI Consolidated Proceedings" as well as the additional
_________________________________________________________________

10. We subsequently upheld the constitutionality of the retroactive
application of the federal jurisdiction provisions of the Price Anderson
Amendments Act. In re TMI Litigation Cases Consolidated II, 940 F.2d
832 (3d Cir. 1991), cert. denied, 503 U.S. 906 (1992).

11. Counsel for the forty-two plaintiffs concede that they filed suit in
Mississippi to take advantage of Mississippi's six-year statute of
limitations. Pennsylvania had a two-year statute. In re TMI, 67 F.3d
1103, 1105 n.3 (3d Cir. 1995), cert. denied, 516 U.S. 1154 (1996).

                               12
legend: "This document Relates to: All Plaintiffs." Id. The
Stipulation further required that pleadings dealing with
issues relating to one or more identified plaintiffs be
captioned "In Re TMI Consolidated Proceedings" and
identify lead counsel, the number of plaintiffs represented
by lead counsel and the number of plaintiffs to whom the
pleadings refer. Id. The Stipulation also expressly provided
that

          3. Nothing in . . . this Stipulation . . . shal l be deemed
          to constitute or affect any waiver of claim, defense or
          issue, including but not limited to the statute of
          limitations, choice of law and bifurcation or
          consolidation for trial of claims, defenses, issues,
          parties or proceedings.

Id. The Stipulation was subsequently approved by the
District Court.

Thereafter, in July of 1992, the defendants filed a motion
for summary judgment directed to the forty-two plaintiffs
who had sued in Mississippi state and federal courts.
Defendants alleged that those claims were untimely under
Section 11(b) of the Price-Anderson Amendments Act of
1988, codified at 42 U.S.C. S 2014(hh) (the choice of law
provisions), which provides that "the substantive rules of
decision in [any public liability action] shall be derived from
the law of the State in which the nuclear incident involved
occurs," and under Section 20(b) of that Act, (the effective
date provision), which provides that "the amendments made
by Section 11" of the Act "shall apply to nuclear incidents
occurring before, on, or after the date of the enactment of
this Act." 42 U.S.C. S 2014 note. The District Court ruled
that the Mississippi actions were time-barred, dismissed
the respective claims, and granted summary judgment in
favor of the defendants because it reasoned thatS 20(b),
read in conjunction with S 11, compelled the retroactive
application of Pennsylvania's two-year statute of limitation
to the plaintiffs' claims. In re TMI Cases Consolidated II, No.
88-14532, slip op. at 2-6 (M.D. Pa. Aug. 16, 1993).

On appeal, the Mississippi plaintiffs argued, inter alia,
that retroactive application of the choice of law provision
violated constitutional guarantees of due process. We

                               13
disagreed, and held that the retroactive application of the
choice of law provision was a rational exercise of Congress'
legislative power. Accordingly, we affirmed the District
Court's grant of summary judgment, and its dismissal of
the claims of the forty-two plaintiffs. In re TMI, 89 F.3d
1106 (3d Cir. 1996), cert. denied, ___ U.S. ___, 117 S. Ct.
739 (1997).

The defendants then moved for summary judgment
against all the TMI plaintiffs, claiming that they had not
breached the duty of care owed to the plaintiffs. The
District Court denied the motion. The court held that state
law on that issue was preempted, and that federal law
determines the standard of care. In re TMI Litigation Cases
Consolidated II, No. 88-1452, slip op. at 36 (M.D. Pa. Feb.
18, 1994). The court also held that federal regulations12 set
the standard of care, and that each plaintiff must prove his
or her individual exposure to radiation in order to establish
causation, but not to establish a breach of the duty of care.
Id. at 30-31. Upon defendants' motion, the District Court
certified the duty of care and causation questions for
interlocutory appeal.13 On that appeal, we held that
plaintiffs must establish that (1) the defendants released
radiation into the environment in excess of the levels
permitted by the federal regulations in effect in 1979; (2)
the plaintiffs were exposed to this radiation, although not
necessarily at the levels prohibited by those regulations; (3)
they have injuries; and (4) radiation was the cause of those
injuries. In re TMI, 67 F.3d 1103, 1119 (3d Cir. 1995), cert.
denied, 516 U.S. 1154 (1996).

After remand, the District Court conducted lengthy in
limine hearings in November of 1995 and in February and
_________________________________________________________________

12. See 10 C.F.R. SS 20.105, 20.106 (1979). These regulations were in
effect at the time of the TMI accident. In re TMI, 67 F.3d 1103, 1108 n.10
(3d Cir. 1996), cert. denied, 516 U.S. 1154 (1996). However, the
regulations have been significantly modified since then. Id. at 1111 n.19.

13. The District Court also certified a question concerning punitive
damages. We held in a separate opinion that punitive damages are
recoverable under the Price-Anderson Amendments Act of 1988 so long
as the money to pay such award does not come from the United States
Treasury. In re TMI, 67 F.3d 1119 (3d Cir. 1995), cert. denied, 517 U.S.
1163 (1996).

                               14
March of 1996, pursuant to Daubert v. Merrell Dow
Pharmaceuticals, Inc., 509 U.S. 579 (1993). Those hearings
all relate to plaintiffs' radiation dose and medical causation
expert witnesses. In January and April of 1996, the District
Court issued several opinions granting the majority of the
defendants' motions in limine. See In re TMI Cases
Consolidated II, 166 F.R.D. 8 (M.D. Pa. 1996) (granting in
part defendants' motions to exclude plaintiffs' medical
causation experts); Id., 922 F. Supp. 1038 (M.D. Pa.
1996)(same); Id., 922 F. Supp. 997 (M.D. Pa. 1996)
(granting in part defendants' motions to exclude plaintiffs'
radiation dose and medical causation experts); Id., 911 F.
Supp. 775 (M.D. Pa. 1996) (granting in part defendants'
motions to exclude plaintiffs' radiation dose experts); Id.,
910 F. Supp. 200 (M.D. Pa. 1996)(same). Although the
District Court was convinced that the majority of the
plaintiffs' expert witnesses were well-qualified, the court
nonetheless "found many of their opinions to be based on
methodologies that were scientifically unreliable and upon
data that a reasonable expert in the field would not rely
upon." In re TMI Litigation Consolidated Proceedings, 927 F.
Supp. 834, 839 (M.D. Pa. 1996). Accordingly, it ruled that
the much of the expert testimony was inadmissible under
Daubert, and its progeny. In April of 1996, the defendants
filed a motion for summary judgment. They based the
motion upon their contention that the District Court's
Daubert rulings left the plaintiff 's with no admissible
evidence as to the radiation dose levels resulting from the
TMI accident.

A subsidiary issue arose during the summary judgment
proceedings as to whom the summary judgment rulings
would apply. That dispute had its beginnings in June of
1993, when the District Court adopted the plaintiffs'
proposed case management plan which called for an"initial
mini-trial of the claims of twelve `typical' plaintiffs," half
chosen by plaintiffs and half chosen by defendants. App. at
168. Under the plaintiffs' plan (which was adopted by the
District Court), discovery would proceed immediately as to
all issues, including punitive damages and, upon
completion of discovery, "the twelve illustrative Plaintiffs
would then proceed to trial on all their claims." Id.

                               15
Ultimately, ten test plaintiffs,14 who have been diagnosed
with the listed illnesses, were chosen.15

When the defendants filed their motion for summary
judgment, they captioned it as pertaining to "All Plaintiffs"
and argued that the District Court's summary judgment
motion should be binding on all plaintiffs, not just the ten
trial or test case plaintiffs. The District Court agreed,
stating:

           The court finds that resolution of the issue before it
          turns on the grounds upon which the court ultimately
          grants or denies summary judgment. Defendants are
          correct that to the extent the ruling turns on broad
          evidentiary issues common to all Plaintiffs, the ruling
          will be binding on all Plaintiffs. Likewise, Plaintiffs are
          correct that insofar as a ruling is based on a more
          narrow, Plaintiff-specific inquiry, the ruling will apply
          only to certain Plaintiffs. The court's reading of
          documents related to the June 15, 1993 order, in
          conjunction with subsequent case management orders
          and evidentiary rulings, indicates that discovery and
          evidentiary matters were to proceed on an "All
          Plaintiffs" basis. A contrary intention or result would
          obviate all benefits of having consolidated the many
          separate actions. Each Plaintiff 's case depends upon
          expert testimony to prove both exposure and medical
          causation. Expert discovery is complete, and all expert
          reports have been filed. Thus, to the extent that the
          expert testimony of record fails to meet the test
_________________________________________________________________

14. As things developed, one of the defendants' test case selections
withdrew from the test group. Consequently, the District Court permitted
defendants to chose one of the parties originally selected by plaintiffs
to
be dismissed from the test case group. In re TMI Litigation Consolidated
Proceedings, 927 F. Supp. 834, 837 n.5 (M.D. Pa. 1996). Thus, the test
case group consisted of ten plaintiffs.

15. Those plaintiffs are: Paula Obercash, acute lymphocytic leukemia;
Gary Villella, chronic myelogenous leukemia; Leo Beam, chronic
myelogenous leukemia; Joseph Gaughan, thyroid cancer; Lori Dolan,
Hurthle cell carcinoma; Jolene Peterson, thyroid adenoma; Richard
Ward, osteogenic carcinoma of the right leg; Pearl Hickernell, breast
cancer; Ethelda Hilt, adenocarcinoma of the ovaries; and Kenneth Putt,
bladder cancer, acoustic neuroma.

                                16
          Plaintiffs' evidentiary burden at this state of the
          litigation, it will fail to meet the same burden as to
          every Plaintiff. It would be an exercise in futility and a
          waste of valuable resources to allow the many separate
          actions consolidated under this caption to proceed if it
          were clear that the cases could not withstand a motion
          for summary judgment. Under such circumstances, the
          court's summary judgment ruling will be applicable to
          all Plaintiffs.

927 F. Supp. at 838.

The District Court ruled on the merits of the summary
judgment motion that the Trial Plaintiffs had failed to
present either direct or indirect evidence of the doses of
cancer inducing levels of radiation that they were exposed
to. Id. at 870. Accordingly, the court extended its grant of
summary judgment to all of the plaintiffs' cases.

          Because the court finds the quantum of evidence on
          the issue of dose to be insufficient, and because no
          Plaintiff will be able to state a prima facie case without
          adequate dose evidence, the instant ruling is binding
          on all Plaintiffs.

Id. at 838. Accordingly, the court granted summary
judgment against all of the plaintiffs, both trial and
nontrial.

These appeals followed.

Appeal Number 96-7623 is the appeal of the ten Trial
Plaintiffs. They argue that the District Court improperly
excluded their proffered expert witnesses' testimony on
dose exposure, thereby erroneously subjecting them to
summary judgment. They do not argue that summary
judgment was improper given the District Court's Daubert
rulings. Thus, if we determine that the District Court's
exclusion of their dose exposure testimony was proper, we
must affirm the summary judgment for the defendants
against the trial plaintiffs. Consequently, the primary issue
for our determination in case number 96-7623 is the
propriety of the District Court's exclusion of testimony of
the dose exposure experts. If, however, we decide that the
court improperly excluded some or all of that evidence, we

                               17
must then decide whether the evidence that was admissible
is sufficient to create a genuine issue of material fact.

Appeal Number 96-7624 is the appeal of all of the TMI
personal injury plaintiffs except the ten Trial Plaintiffs.
Appellants there argue that the District Court improperly
extended its Trial Plaintiffs' summary judgment decision to
them. Appeal Number 96-7625 is the appeal of sanctioned
counsel for the majority of the plaintiffs. Counsel argue that
the District Court's imposition of monetary sanctions
against them for discovery violations was improper. Each
appeal is considered separately.

It is both impractical and unwise to begin our analysis of
the Daubert challenge to the scientific testimony without
first providing a brief discussion of the fundamental
principles of nuclear physics, nuclear engineering, the TMI-
2 accident, ionizing radiation, and the health effects of
ionizing radiation on the human body. These scientific
principles are at the center of the damage that plaintiffs
claim they suffered as a result of the TMI accident and the
District Court's Daubert rulings. Total immersion in the
complexities of these disciplines is neither required, nor
possible. Accordingly, we offer the following overview of the
controlling principles with an awareness that doing so
stretches the boundaries of our institutional competence,
and with a recognition of our need to borrow heavily from
others in academic disciplines far from the familiar confines
of the law.

III. SCIENTIFIC BACKGROUND

A. Overview of Relevant Principles of Nuclear Physics.

1. Atomic and Nuclear Structure.

Plaintiffs alleged that the accident at TMI resulted in a
release of radiation into the atmosphere that caused
changes to the atomic structure of their chromosomes and
resulted in the formation of neoplasms. Their allegations
thus implicate the structure of the atom -- the basic

                               18
building block of matter -- and the physics of orbiting
electrons.16

The atom consists of a small but massive central nucleus
surrounded by one or more orbital electrons. JOHN R.
LAMARSH, INTRODUCTION TO NUCLEAR ENGINEERING 8 (2d ed.
1983). Orbiting electrons are negatively charged, much
smaller in mass than the neutron, and their distances from
the nucleus are much larger than the radius of the
nucleus. DAVID BODANSKY, NUCLEAR ENERGY: PRINCIPLES, PRACTICES
AND PROSPECTS 346 (1996). The average distance from the
nucleus to the place where the outermost electron is found
provides an approximate measure of atomic size. This
distance is approximately the same for all atoms, except a
few of the lightest atoms, and is about 2 #46# 10 -8 centimeters.17
LAMARSH, at 11.

The nucleus has two constituent parts of approximately
equal mass -- the neutron and the proton.18 BODANSKY, at
346. Each is much more massive than the electron.
LAMARSH, at 6-7. Together, they are called nucleons.
BODANSKY, at 346. The neutron and proton differ in that the
neutron is neutral while the proton has a positive charge
equal in magnitude to the negative charge of the electron.
Id. An atom is neutral or "un-ionized" when the number of
positively charged protons equals the number of negatively
charged electrons. D. J. BENNET, ELEMENTS OF NUCLEAR POWER
1 (2d ed. 1981).19 "Nuclides" are very important to our
_________________________________________________________________

16. As we discuss below, radiation has the potential to fatally interfere
with one of more orbiting electrons.

17. It is difficult to define the exact size of an atom because the
orbiting
electrons may at times move very far from the nucleus but at other times
pass close to it. LAMARSH, at 7.
18. At one time, it was believed that neutrons and protons were the
fundamental particles of nature. However, it is now understood that they
are not the fundamental particles of nature, but themselves are
composed of more elementary particles called quarks. BODANSKY, at 346.
While knowledge of the existence of quarks and other elementary
particles is crucial to an understanding of the origins of the universe
and
of the ultimate structure of matter, their existence can be ignored in a
discussion of nuclear reactors, radioactivity and nuclear fission. Id.

19. Forces exist in an atom that are critical to atomic structure.
"Coulomb repulsion" is an electrostatic force, governed by Coulomb's

                                19
discussion. They are differing "species" of atoms whose
nuclei contain particular numbers of protons and neutrons.
LAMARSH, at 8. A nuclide is given the shorthand notation AZ
X, where X is the symbol for the chemical element, Z is the
atomic number and A is the atomic mass number. KNIEF, at
29. In general practice, however, the subscript Z is omitted
_________________________________________________________________

law, which exists between objects that carry the same electrical charge.
BODANSKY, at 349 n.3. The repulsion exists not only on a macroscopic
scale, but also on an atomic scale, BENNET, at 8, and, therefore, it
exists
between the protons in the nucleus because they are positively charged.
Consequently, Coulomb repulsion tends to disrupt (or burst) the
nucleus. Id. The fact that the nucleus of a stable atom is not disrupted
indicates that there is another force which overrides Coulomb repulsion,
and holds the nucleus together. Id. This force, known as the "strong" or
"nuclear force", exists between particles that are incredibly close to
each
other, within about 3 #46# 10-15 meters. The strong force acts with
approximately equal strength between two protons, two neutrons or a
proton and a neutron and binds the nucleus together, so long as the
separation between the particles is less than 3#46# 10-15 meter space in
which the strong force operates to cancel Coulomb repulsive. Id.

Coulomb repulsion is not the only electrostatic force defining atomic
structure. "Coulomb attraction" exists between oppositely charged
particles and this attractive force, operating between the electrically
positive protons and the electrically negative electrons, causes the
electron to orbit around the nucleus of the atom. RONALD ALLEN KNIEF,
NUCLEAR ENGINEERING: THEORY AND TECHNOLOGY OF COMMERCIAL
NUCLEAR POWER

29 (2d ed. 1992).

The chemical properties of an element are determined by the number
of electrons surrounding the nucleus in an un-ionized atom, and the
number of electrons orbiting the atom is equal to the number of protons
in the nucleus. BODANSKY, at 346. That is, a neutral atom has the same
number of protons and electrons, and the number of protons in the
nucleus, (given the symbol "Z"), is the atomic number of a particular
element and identifies it. KNIEF, at 29. Electrons are responsible for the
chemical behavior of the atoms and they identify the chemical elements.
LAMARSH. at 8. Consequently, each element is identified in terms of its
atomic number, Z. BODANSKY, at 346.

The number of neutrons   in the nucleus is known as the "neutron
number" and is denoted   by the letter "N". L AMARSH, at 8. The sum of the
number of neutrons and   protons, i.e., nucleons, in the nucleus is called
the atomic mass number   or "mass number", A. Thus, the formula: A =
Z + N. Id.
20
because once the element, X, is given, so is the atomic
number, Z. BODANSKY, at 346. Nuclides whose nuclei contain
the same number of protons, i.e., the same Z, but different
numbers of neutrons, i.e., different N and therefore a
different mass number, A, are called isotopes of the
element. BENNET, at 2. All elements have a number of
isotopes, Id., and they are virtually identical in their
chemical properties to the elements they are isotopes of.
BODANSKY, at 346. However, the masses and other
characteristics of their nuclei are different. BENNET, at 2. An
isotope of an element is given the same shorthand notation
as the nuclide. For example, naturally occurring oxygen,
whose chemical symbol is "O", consists of three isotopes, 16
O, 17O, and 18O. Id. Each has 8 protons and electrons, i.e.,
the same atomic number, Z, but they have 8, 9 and 10
neutrons respectively, i.e., different N (N = A - Z). The nuclei
of a given element can have the same mass number, A, but
have a different atomic number, Z, in which case it is called
an isobar. BODANSKY, at 346.

Though counterintuitive in the extreme, it is nevertheless
a fact of atomic structure that the mass of an atom is less
than the sum of the masses of its constituent parts. BENNET,
at 4; BODANSKY, at 350; KNIEF, at 29; LAMARSH, at 28. The
difference between the mass of the assembled atom and the
sum of the mass of the component atomic parts is known
as the "mass defect". KNIEF, at 29. However, mass is not
really lost in the assembly of an atom from its component
parts. Rather, the mass defect is converted into energy
when the nucleus is formed. Id. The conversion is explained
by the "principle of the equivalence of mass and energy in
which Einstein stated that mass and energy are different
forms of the same fundamental quantity."20 BENNET, at 4.
Therefore, in any reaction where there is a reduction in
mass, the decrease is accompanied by a release of energy.
Id. The energy associated with the mass defect is called
"binding energy" and it represents the total energy that
would be required to disassemble a nucleus into its
constituent neutrons and protons. BODANSKY, at 350.
_________________________________________________________________

20. The equivalence between mass and energy is expressed in Einstein's
famous equation, E = mc2, where E is energy, m is mass and c is the
speed of light. KNIEF, at 28.

                               21
Binding energy increases in a nucleus   as the number of
particles in the nucleus increase. In   other words, binding
energy increases with a corresponding   increase in atomic
mass number. LAMARSH, at 28. However,   the rate of increase
is not uniform. KNIEF, at 30.

The amount of binding energy in a nucleon is important
when determining possible sources of nuclear energy.
LAMARSH, at 28. A nuclei is stable or tightly bound when the
binding energy per nucleon is high. Accordingly, a relatively
large amount of energy must be supplied to break the
stable nuclei apart. Id. When a tightly bound nucleus is
broken apart and two nuclei of intermediate mass are
formed, a relatively large amount of energy is released.
BENNET, at 7. In contrast, nuclei with low binding energy per
nucleon are easily broken apart, and less energy is
released. LAMARSH, at 29.

The now familiar term, "nuclear fission" refers to the
process of causing a tightly bound nucleus to split into two
nuclei of intermediate mass. Id. The process proceeds in the
direction of increased binding energy per nucleon. B ENNET,
at 7. That is, the nuclei of intermediate mass created by the
fission process have greater binding energy than the
original nucleus. LAMARSH, at 30. When the nuclei of
intermediate mass have greater binding energy than the
original nucleus, energy is released during the formation of
the final nuclei. BODANSKY, at 351. This energy that is
released as a result of the fission process is the source of
energy in a nuclear reactor. LAMARSH, at 30. It is what we
commonly refer to as "nuclear energy".

Atoms can exist only in certain states or configurations,
with each state having its own specific energy. B ODANSKY, at
351. The different energy states correspond to different
electron orbits of different radii, LAMARSH, at 15, each with
an energy level equal to the sum of the kinetic and
potential energies of the electron in its orbit. B ODANSKY, at
351. The lowest state of energy is called the "ground state"
and it is the state in which the atom is normally found.
LAMARSH, at 15. However, an electron can, as a result of a
nuclear reaction, jump from its normal orbit to an orbit
that is farther from the nucleus. An increase in energy
corresponds to this "jump", and when an atom has more

                               22
energy than its ground state it is said to be in an"excited
state". BENNET, at 8. An atom can have a number of excited
states which correspond to the number of jumps the
electron has made. Id. The highest energy state occurs
when the electron is completely removed from the atom.
LAMARSH, at 15. The complete removal of an electron from an
atom is called "ionization" and the resulting atom is said to
be "ionized". Id.

The nucleons in the nuclei also move in orbits; however,
the orbits of nucleons are not as well defined, and are not
as well understood, as the orbits of electrons. L AMARSH, at
16. Like atoms, nuclei normally exist in the ground state.
BENNET, at 8; BODANSKY, at 352. However, nuclei can reach
excited states just as atoms can. BENNET, at 8; BODANSKY, at
352. The process is more complicated in nuclei than in
atoms because excitation of nuclei can result in several
nucleons being raised to excited levels simultaneously.
BENNET, at 8. Although it is not yet possible to account
theoretically for the exact energy levels of nuclei, as it is
possible to do so for atoms. BODANSKY, at 352. It is generally
true that the energies of the excited states and the energies
between states are much greater for nuclei than for atoms.
LAMARSH, at 16. The greater energy results from the greater
forces acting between nucleons. These forces are much
stronger that the forces acting between electrons and the
nucleus. Id.

With a few exceptions, excited states in either atoms or
nuclei exist for only a very short time, about 10 -14 seconds.
BENNET, at 9. Excess energy is quickly emitted and the
system, either atomic or nuclear, decays to states of lower
energy until it ultimately returns to its ground state.
LAMARSH, at 15. The process of going from one state to
another is called a "transition". Id. The energy lost in a
transition is usually carried off by electromagnetic
radiation,21 BENNET, at 9; BODANSKY, at 352, with the lost
_________________________________________________________________

21. Sometimes, however, the energy can be transferred to an electron
through a process known as "internal conversion" which leaves the
nuclide unchanged. At other times, an excited state can decay be
emitting a particle, such as a beta (b) particle or a neutron, thus
changing the atomic number of the nuclide. BODANSKY, at 352 n.8.

                               23
energy equal to the difference in the energies of the two
states.22 LAMARSH, at 15.

2. Radioactivity.

As suggested by our discussion thus far, nuclei are either
stable or unstable. For all practical purposes, stable nuclei
remain unchanged forever. Unstable nuclei decay
spontaneously into lighter nuclei pursuant to a time scale
that is unique for every element (the "half-life").23 The half-
life for a given element is defined as the time required for
one-half of a given sample of the element to "decay." If the
half-life is greater than some undefined fraction of a
second, the process of decay is called "radioactivity." Half-
lives vary from less than a second to many billions of years.
BODANSKY, at 353. Radioactivity is then, the process by
which unstable nuclei seek stability. KNIEF, at 31.
Frequently, the original unstable nucleus, called the
"parent nucleus", decays to another radioactive nucleus,
called the "daughter nucleus." LAMARSH, at 19. There may be
more than one radioactive daughter nuclei produced until
stability is reached. BENNET, at 11. This process of the
creation and subsequent decay of several daughter nuclei is
referred to as a "decay chain". LAMARSH , at 19.24
_________________________________________________________________

22. The electromagnetic radiation corresponding to an atomic or nuclear
transition is contained in a single discrete packet called a "photon".
BODANSKY, at 352. At one time, light and other forms of electromagnetic
radiation were described as waves. However, it is now known that
electromagnetic radiation behaves at times like a particle. Id. Thus, a
photon is both wave-like and particle-like in character. LAMARSH, at 7.
Visible light is associated with transitions involving the outer electrons
of atoms. X rays correspond to transitions involving the inner electrons
of atoms. Gamma (g) rays correspond to transitions from nuclei.
However, all are photons and there is no difference among them other
than their energy, with visible light having the lowest energy and gamma
(g) rays having the highest energy. In fact, there is really no need to
distinguish between photons from atomic transitions, i.e., x rays, and
photons from nuclear transitions, i.e., g rays. The names date from the
time of their discovery and are probably kept only as a reminder of their
origin. BODANSKY, at 352.

23. Sometimes designated as: "T1/2 ".

24. For example, there are three natural radioactive decay chains whose
parent isotopes have very long-half lives. The three are uranium 238 (T1/2
= 4.51 x 109 years), uranium 235 (T1/2 = 7.1 46 x 108 years), and thorium
232 (T1/2 = 1.41 x 1010 years), and their decay chains contain many
radioactive daughter isotopes leading eventually in each case to a stable
isotope of lead. BENNET, at 18-19.
24
The exact time at which any single nucleus will decay
cannot be determined. KNIEF, at 34. However, the average
behavior of a very large sample of radioactive material can
be described statistically. BENNET, at 15. For a given nuclide,
there is an average time, called the "decay constant", which
characterizes its rate of decay. Id. The decay constant is
defined as the probability per unit of time that a decay will
occur. KNIEF, at 34. The amount of radioactivity present
during a decay is referred to as "activity". F RED A. METTLER,
JR., M.D., AND ARTHUR C. UPTON, M.D., MEDICAL EFFECTS OF
IONIZING RADIATION 7 (2d ed. 1995) (hereinafter "MEDICAL
EFFECTS"). The activity of a given sample is the average
number of disintegrations per unit of time. For a large
sample, the activity is the product of the decay constant
and the number of atoms present. Id. The traditional unit
for measuring radioactivity is the curie (Ci), which is
defined as 3.7 #46# 1010 disintegrations per second.25

A radioactive nuclide is called a "radionuclide." KNIEF, at
32. During the process of radioactive decay, the nucleus
spontaneously emits an alpha (a) particle or a beta (b)
particle. BODANSKY, at 354. The emission of these particles is
often accompanied by the emission of one or more gamma
(g) rays. Id. An alpha (a) particle is a highly stable nucleus
of the isotope helium 4 (4He), consisting of two protons and
two neutrons. LAMARSH, at 20.26 Alpha (a) particles have a
double positive charge and are emitted in a discrete energy
spectrum. Id. They have a low level of energy and, therefore,
are only capable of penetrating matter a small distance.27

Decay by alpha particle emission is rather rare for
nuclides lighter than lead (Pb) which has an atomic number
(Z) of 82. BODANSKY, at 355. However, many of the naturally
_________________________________________________________________

25. The curie, is however, being superseded by a new measuring unit
called the "Becquerel" (Bq), which is defined as one disintegration per
second. BENNET, at 16.

26. Thus, the emission of an alpha (a) particle reduces the atomic
number (Z) of the unstable nuclei by two and the mass number (A) by
four. LAMARSH, at 20.

27. The most energetic of the alpha (a) particles are stopped after
passing through less than 10 centimeters of air or about 0.1 millimeters
of a material such as water. BODANSKY, at 355.

                               25
occurring radioactive elements with atomic numbers
between 84 (polonium) and 92 (uranium), i.e., the heavier
elements, decay by alpha particle emission. BENNET, at 13.
When these elements decay, the daughter product is closer
to the stability region than the parent. Id. In addition, the
daughter nucleus of these heavier elements is frequently
formed at an excited state of energy so that the excited
nucleus immediately decays further to its ground state by
the emission of gamma (g) radiation. Id. Thus, the decay of
a heavy radioactive isotope by alpha particle emission also
produces gamma (g) radiation. Id.

A beta (b) particle is an electron of nuclear, not orbital,
origin, KNIEF, at 33, but it is identical to the electrons that
orbit the nucleus. BODANSKY, at 355. Because it is an
electron, it has much less mass than an alpha particle. Id.
A neutron that is bound into the nucleus is not stable.
LAMARSH, at 7. During decay, a neutron in the nucleus is
transformed into a proton and an electron and it is this
electron which is emitted as a beta (b) particle. Id.; BENNET,
at 13.

Because beta (b) particle decay has the effect of
transforming one of the neutrons into a proton, the
resulting daughter nucleus has the same mass number   (A)
as the parent, but its atomic number (Z) is greater   by one.
Id. Moreover, the daughter nucleus may be formed in   an
excited state, and decay to its ground state by the   emission
of gamma (g) radiation. Id.

In most cases, beta particles are negatively charged and
are more properly designated as b- particles. Positive
electrons, called "positrons" or b+ particles, are emitted from
artificial radionuclides that are produced when positive
particles, such as protons or alpha (a) particles, combine
with a nucleus to form an unstable proton-rich nucleus.
BODANSKY, at 355. These beta particles are very rare in
naturally existing material. Id.

Beta (b) particles do not all have the same energy. BENNET,
at 13. The spectrum of the energy of these particles, ranges
from zero to a fixed maximum or "endpoint energy."
BODANSKY, at 357.28 However, the average energy of beta
_________________________________________________________________

28. The endpoint energy corresponds to the mass difference between the
parent atom and the residual product, as the principle of conservation of
mass plus energy demands. BODANSKY, at 357.

                               26
particles is about one-third, BENNET, at 13, to one-half,
BODANSKY, at 357, the endpoint energy. The remaining two-
thirds to one-half of maximum possible beta (b ) particle
energy is shared with another particle called the neutrino.29
BENNET, at 13; BODANSKY, at 357. A neutrino is one of
nature's more curious phenomena. It has no charge, and
virtually no mass. KNIEF, at 33. It was once thought to have
no mass; however, it is now believed that the neutrino may
have mass, albeit very small mass. BODANSKY, at 357;
Malcolm W. Browne, Los Alamos Experiment Shows
Neutrino Probably Has Mass, N.Y. Times, May 7, 1996.

Beta (b) particle decay usually occurs when a nuclide has
an excess of neutrons. BENNET, at 13; B ODANSKY, at 358. A
beta particle has greater penetrating ability than an alpha
particle, BENNET, at 21, with average penetration distances
ranging from 0.1 to 1 g/cm2, increasing with increasing
energy. BODANSKY, at 355. A neutrino, however, has great
penetrating power and can pass through very large
amounts of material without stopping. Id. at 358.

As discussed earlier, gamma (g) radiation is
electromagnetic radiation emitted in the form of photons by
nuclei in excited states of energy. Except as noted below,
gamma (g) emission is not a primary process of radioactive
decay. Instead, it follows alpha (a) particle or beta (b)
particle emission. Gamma (g) rays do not have mass or
charge, and they are therefore capable of much greater
penetration of matter than alpha (a) or beta (b) particles.30
BODANSKY, at 355.

Earlier, we noted that excited states in nuclei exist for a
very short time (about 10-14 seconds). Consequently, half-
lives for gamma (g) ray emission are typically very short.
BODANSKY, at 359. However, some nuclei have long-lived
_________________________________________________________________

29. Strictly speaking, the neutrino emitted in b#48# decay is an anti-
neutrino, while the neutrino itself is emitted in b+ decay. When the
distinction between them is not important, they are both referred to as
neutrinos. Again, strictly speaking, the b#48# and neutrino are called
particles, while the b+ and anti-neutrino are called anti-particles.
BODANSKY, at 357.

30. Gamma rays can penetrate to distances ranging from 5 to
20 g/cm2. BODANSKY, at 355.

                               27
excited states, called "isomeric states", with half-lives
ranging from a fraction of a second to many years. Id. In
fact, in some cases, the excited state is so long that the
nuclei appear semi-stable. LAMARSH, at 21. The decay to a
lower state of energy by gamma (g) ray emission in a nuclei
in an isomeric state is called an "isomeric transition". Id. In
such a case, gamma (g) ray emission appears to be the
primary radioactive process of, rather than incident to,
alpha (a) or beta (b) particle emission. Gamma ray emission
can, however, ultimately be traced back to either initiating
process.31 BODANSKY, at 359.

3. Ionizing Radiation.

The legal dispute before us is rooted in the damage that
purportedly resulted from defendants' release of ionizing
radiation into the atmosphere. There are a number of ways
in which an ion, or charged particle, can interact with an
atom. First, because it is charged, the particle exerts an
electrostatic or "Coulomb force" on the atom's electrons.
The exertion of Coulomb force has various effects upon an
atom. One or more of the electrons may move to an outer
orbit, leaving the atom in an excited state of energy or an
electron may be entirely ejected from the atom. The latter
event results in the formation of an ionized atom. L AMARSH,
at 88. When an atom is ionized, it is split into an ion pair.
The negatively charged electron of this pair is the negative
ion, and the atom minus its negatively charged electron is
the positive ion. BENNET, at 20. This process of ionization
produces ionizing radiation.32 MEDICAL EFFECTS, at 1.

The second possible result is that the charged particle
may penetrate the cloud of orbiting electrons and collide
with the nucleus. After collision, the charged particle is
scattered from the nucleus, and, since momentum and
_________________________________________________________________

31. There is an alternative to gamma (g) ray emission called "internal
conversion", in which the excitation energy is transferred to one of the
inner electrons of the atom. Typically, gamma (g ) ray radiation and
internal conversion are competing processes by which excited nuclei
reach the ground state. BODANSKY, at 359.

32. Ionizing radiation is only a small part of the electromagnetic
spectrum, which includes radio waves, radar, microwaves, ultraviolet
radiation and electric power. MEDICAL EFFECTS, at 1-2.

                               28
energy are conserved in the collision, the nucleus recoils. If
the charged particle has sufficient mass and energy, the
recoiling nucleus may be ejected from its own electron
cloud and itself become a charged particle. LAMARSH, at 88.
In addition, under certain circumstances, the charged
particle, particularly if it is an alpha (a) particle, may
undergo a nuclear reaction when it collides with the
nucleus. The charged particle may also be accelerated by
the electrostatic or Coulomb field of the electrons or the
nucleus and a photon may be emitted.33 Id.

Whichever of these alternative results occurs, a charged
particle is created. When a charged particle passes through
matter, it excites and ionizes atoms in its path. Id.
However, these charged particles lose energy by virtue of
the electrostatic forces created by their interaction with the
atoms that comprise the matter through which the charged
particles pass. KNIEF, at 70. The electrostatic forces acting
upon the charged particles are proportional to the product
of the charges and inversely proportional to the square of
the distance between them. Thus, the force decreases
rapidly with distance, but becomes negligible only at very
large distances. Id. At any given interval, a charged particle
experiences forces from a very large number of electrons.
The resulting energy losses are well defined for each
charged particle and each material medium. Id. The net
macroscopic effect of charged-particle interactions is
characterized by range and linear energy transfer ("LET").
Id. Range is the average distance traveled by a charged
particle before it completely stops. The LET is the amount
of energy deposited per unit of particle track, which gives
rise to the excitation and ionization. LAMARSH , at 89. The
range and the LET of a specific radiation contribute to the
effect they have on a material, with the range determining
the distance of penetration and the LET determining the
distribution of energy deposited along the path. K NIEF, at
70.

The LET is of particular significance to an inquiry into
the biological effects of radiation. Those effects depend
_________________________________________________________________

33. This latter kind of radiation that is emitted when a charged particle
becomes accelerated, is called "bremsstrahlung". Id. LAMARSH, at 88.

                               29
upon the extent to which energy is deposited by radiation
as excitation and ionization within a given biological
system. LAMARSH, at 89. The LET increases with the mass
and charge of a moving particle. Id. Consequently, heavy
charged particles, such as alpha (a) particles, are referred
to as high LET radiation. Id.

Charged particles, are referred to as "directly ionizing
radiation" because they are directly responsible for
producing ionization. LAMARSH, at 88; B ENNET, at 20;
BODANSKY, at 354. Uncharged particles, such as gamma (g)
rays, lead to excitation and ionization only after interacting
with matter and producing a charged particle. Accordingly,
uncharged particles are referred to as "indirectly ionizing
radiation." LAMARSH, at 88.

While gamma (g) rays can interact with matter in a
variety of ways, there are, for purposes of our analysis,
three important types of interaction between gamma (g)
radiation and matter -- the "photoelectric effect", "pair
production" and "Compton scattering." BENNET, at 21.
Because very short-range forces govern electromagnetic
mechanisms, a gamma (g) ray must essentially"hit" an
electron for an interaction to occur. KNIEF, at 71. In the
photoelectric effect, which is the most important process at
low gamma (g) ray energies, BENNET, at 199, the gamma (g)
ray interacts with the entire atom, the gamma (g ) ray
disappears and one of the atomic electrons is ejected from
the atom. LAMARSH, at 79. As a result, the energy of the
gamma (g) ray or photon is converted completely to kinetic
energy of an orbital electron. KNIEF, at 71. If the gamma (g)
ray ejects an inner electron, the resulting hole in the
electron cloud is filled by one of the outer electrons.
LAMARSH, at 16, 79. This transition is accompanied either by
the emission of an X ray or by the ejection of another
electron.

Pair production occurs only for high-energy gamma (g)
rays and only in the vicinity of a heavy nucleus. Id. at 80;
BENNET, at 21. The gamma (g) ray is annihilated; and an
electron pair -- a positron and a negatron -- is created.
LAMARSH, at 80. When this occurs the energy of the gamma
(g) ray converted to mass, and kinetic energy of the electron
pair. KNIEF, at 71. Once they are formed, the positron and

                               30
negatron move around and ultimately lose energy as a
result of collisions with atoms in the surrounding matter.
LAMARSH, at 80. After the positron has slowed to very low
energies, it combines with a negatron, the two disappear
and two photons are produced. LAMARSH, at 80-81. The
photons that are produced are called "annihilation
radiation." Id. at 7.

Compton scattering occurs when the gamma (g) ray
strikes an electron and is scattered. The electron that is
struck in this process recoils and acquires some of the
kinetic energy of the gamma (g) ray, Id. at 81, thus reducing
the energy level of the reaction. KNIEF, at 71. Since the
gamma (g) ray does not disappear as it does during the
photoelectric effect, and is not annihilated as it is in pair
production, the Compton-scattered gamma (g) ray is free to
interact again. LAMARSH, at 82.

Although uncharged particles cause indirect ionizing
radiation, it is nonetheless possible to refer to the LET of
uncharged particles. However, because they have a
relatively low rate of energy loss when compared to the rate
of energy loss of charged particles, gamma rays (g) are
referred to as "low LET radiation." LAMARSH, at 89. The
distinction between high LET radiation and low LET
radiation has important biological consequences. Id. Given
the same dose of radiation, biological damage from high
LET radiation is much greater than damage from low LET
radiation. Id. at 402.

4. Radiation Quantities and Units.

Radiation can be measured by counting the number of
ionized particles it produces as it passes through air.
INTERNATIONAL ADVISORY COMMITTEE, THE INTERNATIONAL CHERNOBYL
PROJECT, TECHNICAL REPORT 20 (1991) (hereinafter "CHERNOBYL
"). Originally, the amount of radiation exposure for X- and
gamma (g) radiations was measured in units of the roentgen
(R), KNIEF, at 72, which is defined as the number of
electrical charges produced in a unit mass of air.
CHERNOBYL, at 20.34 Alternatively, a roentgen can be defined
_________________________________________________________________

34. One roentgen is that quantity of X or gamma (g) radiation which
produces a total charge of one electrostatic unit of either sign in one
cubic centimeter of air at 1 atmosphere at 0o Celsius. LAMARSH, at 400.

                                31
in terms of the amount of energy released in the production
of ions with a total charge of one electrostatic unit of either
sign. BENNET, at 197.35 Thus, the roentgen is a unit of
exposure in air and not a unit of radiation dose to body
tissue. Moreover, it is not applicable to higher energy X-
rays or to particulate radiations. MEDICAL EFFECTS, at 8.
Consequently, the roentgen is not very useful for comparing
the effects of various radiations on biological systems,
particularly the human body. KNIEF, at 73.

When radiation penetrates material, its energy is
absorbed and released by the constituent atoms of the
material that is penetrated. CHERNOBYL, at 20. The absorbed
energy per unit mass of material is termed the "absorbed
dose." Id.36 Two units are used to measure absorbed dose of
any type of radiation. The original unit of absorbed dose is
the "rad" (radiation absorbed dose) and is defined as 100
ergs of energy per gram of material. LAMARSH, at 401. The
new unit of absorbed dose under the Systeme International
d'Unites ("SI")37 is the gray ("Gy"), which is defined as one
joule of energy absorbed per kilogram of matter. CHERNOBYL,
at 20. Because a rad and a gray are defined in terms of
energy, it is possible to equate rads with grays, with one
gray being equivalent to 100 rads (1Gy = 100 rads), or one
_________________________________________________________________

35. Under this definition, a roentgen is equivalent to depositing about 88
"ergs" in 1 gram of air. KNIEF, at 73. An "erg" is a unit of energy and
one
roentgen under the alternative energy description is energy sufficient to
move the point of a sharpened pencil about 1.5 millimeters across a
piece of paper. Id.

36. Heavy, highly charged particles, such as alpha (a) particles, lose
energy rapidly over distance and, therefore, do not penetrate matter
deeply. For example, alpha (a) particles do not penetrate the layer of
dead cells on the surface of the skin. CHERNOBYL, at 19. Beta (b)
particles,
because of their smaller charge and much smaller mass, are much more
penetrating, BENNET, at 20, and may penetrate up to several centimeters
into the body. CHERNOBYL, at 19. X- and gamma (g) rays have much
greater penetrating power than either alpha (a ) or beta (b) particles,
BENNET, at 20, and they are therefore used for medical diagnostic
purposes. CHERNOBYL, at 19.

37. The SI is a modernized metric system which is becoming the
standard for expressing scientific and technical data. However, much
scientific and technical literature still contains the older, more
customary units. KNIEF, at 671

                               32
rad equivalent to 10 milligrays (1 rad = 10 mGy). 38 MEDICAL
EFFECTS, at 8.

However, the absorbed dose is not the only factor to be
considered in estimating radiation effects on the human
body. The effects also depend on the LET of the radiation.
KNIEF, at 73; LAMARSH, at 402. Even when the amounts of
energy absorbed are the same, alpha (a) particles are more
damaging to human tissue than gamma (g) radiation
because of the higher LET of alpha (a) radiation. BENNET, at
198. The fact that different types of radiation have different
biological effects for the same absorbed dose is described in
terms of the relative biological effectiveness ("RBE") of the
radiation. LAMARSH, at 402. The RBE depends on the dose,
the dose rate, the physiological condition of the subject,
and various other factors. The RBE is determined through
experimentation. KNIEF, at 73; LAMARSH, at 403. Accordingly,
there is no one RBE for a given type of radiation, and the
unit is used almost exclusively in radiobiology. L AMARSH, at
403.

RBE is, however, used to approximate the quality factor
("Q") of radiation, which is usually the upper limit of RBE
for a specific type of radiation. Id.; K NIEF, at 73. For
example, X-rays and gamma (g) rays have a Q of 1, beta (b)
particles have a Q of 1 to 1.7, depending on their energy,
and alpha (a) particles have a Q of 20. C HERNOBYL, at 20;
KNIEF, at 74. To estimate the effect of a given type of
radiation on body tissue, it is necessary to determine the
dose equivalent. The dose equivalent is arrived at by
multiplying the absorbed dose by the quality factor of the
radiation. The original unit of dose equivalence is the "rem"
(roentgen equivalent man) and is the product of the
absorbed dose in rad and the Q of the particular radiation.
LAMARSH, at 404. Thus, if the radiation is gamma (g)
_________________________________________________________________

38. There is another type of unit which is sometimes used for very high
energy radiation and for particulate radiation. That unit is the "kerma"
(kinetic energy released inmatter) and it is used because it includes not
only the energy deposited in the local area but also the additional energy
deposited as a result of bremsstrahlung. For most purposes, the rad and
the kerma are interchangeable. A major exception is the calculation of
doses for atomic bomb survivors. There, the kerma was higher than the
rad. MEDICAL EFFECTS, at 8.

                               33
radiation, then an absorbed dose of 1 rad produces a dose
equivalent of 1 rem, and if the radiation is alpha (a) particle
radiation, then an absorbed dose of 1 rad produces a dose
equivalent of 20 rem. The new SI unit of dose equivalence
is the sievert (Sv) and is the product of the absorbed dose
in gray (Gy) and the Q of the radiation. BENNET , at 198.
Since one gray equals 100 rads (1 Gy = 100 rads), then one
sievert equals 100 rem (1 Sv = 100 rem), LAMARSH , at 404,
or one rem equals 10 millisieverts (1 rem = 10 mSv).
MEDICAL EFFECTS, at 8.

The effect of a given dose equivalent varies depending on
the tissue or organ exposed to the radiation. CHERNOBYL, at
20. For example, a given dose of radiation to the hand may
have a different and far less serious effect than the same
dose delivered to a blood-forming organ. Similarly, the
biological effect of a given dose of radiation to a blood-
forming organ will be different from a like exposure to
reproductive tissue. LAMARSH, at 404. However, equal dose
equivalents from different sources of radiation, if delivered
to the same point in the body, should have approximately
the same biological effect. Id. at 403.

The "effective dose" (E), is a unit that is derived from the
equivalent dose in an attempt to indicate the combined
effect of different doses of radiation upon several different
tissues or body parts. CHERNOBYL, at 20. The effective dose
is the product of the equivalent dose in a tissue or organ (T)
multiplied by a factor called the "tissue weighing factor"
(WT), which represents the contribution of that tissue or
organ to the total harm resulting from uniform radiation
exposure to the whole body. Id.39

Each of the preceding units, (i.e., absorbed dose,
equivalent dose and effective dose) relate to the radiation
exposure of an individual. There are, however, units of
exposure for groups of people. They are arrived at by
_________________________________________________________________

39. By way of illustration, the tissue weighing factor for the gonads is
0.20, the tissue weighing factor for red bone marrow is 0.12, and the
tissue weighing factor for the skin and bone surface is 0.01. CHERNOBYL,
at 20. The effective dose is the weighted sum of the equivalent doses in
all the tissues and organs of the body and is a measure of the total risk
from any combination of radiations affecting any organs of the body. Id.

                               34
multiplying the average dose to the exposed group by the
number of people in the group. CHERNOBYL, at 20-21. The
units are the "collective equivalent dose," which relates to a
specified tissue or organ, and the "collective effective dose,"
which relates to all the people exposed to the radiation. Id.
Both units are expressed in terms of man-rems or man-
sieverts. LAMARSH, at 405, and they represent the total
consequences of the exposure of a population or group.
CHERNOBYL, at 21.

5. Health Effects of Ionizing Radiation.

Soon after the discovery of x-rays and natural
radioactivity, clinical evidence suggested that ionizing
radiation is harmful to human tissue. ANNALS OF THE
INTERNATIONAL COMMISSION ON RADIOLOGICAL PROTECTION, ICRP
PUBLICATION 60, 1990 RECOMMENDATIONS OF THE INTERNATIONAL
COMMISSION ON RADIOLOGICAL P ROTECTION 94 (1990)(hereinafter
"ICRP 60"). The initial evidence was mainly noted from the
effect of ionizing radiation on human skin.40 Id. at 92.
Later, scientists realized that exposing germinal tissue in
plants and animals to ionizing radiation produced effects
not only in the plants and animals that were actually
exposed, but also in subsequent generations of the exposed
plants and animals. Id. Scientific studies and investigations
over the last century, have now given us a wealth of
information about the effects of radiation on humans.41
These studies include extensive in vitro and in vivo animal
experiments, Id., the comprehensive epidemiological studies
of the survivors of the atomic bombings of Hiroshima and
Nagasaki, studies of x-rayed tuberculosis patients; and
studies of people exposed to ionizing radiation during
treatment for ankylosing spondylitis, cervical cancer and
tinea capitis. NATIONAL RESEARCH COUNCIL, COMMITTEE ON THE
BIOLOGICAL EFFECTS OF IONIZING RADIATIONS, HEALTH EFFECTS OF
EXPOSURE TO LOW LEVELSOF IONIZING RADIATION 2(1990)
_________________________________________________________________

40. Ionizing radiation causes nonmalignant skin damage called erythema
or reddening of the skin. LAMARSH, at 409.

41. One commentator has noted that "more than 80,000 studies have
been reported in the scientific literature, indicating that radiation
effects
have been studied far more thoroughly than other environmental
impacts." KNIEF, at 77.

                               35
(hereinafter "BEIR V"). These studies have allowed science
to "narrow the range of uncertainties in human
radiobiology." CHERNOBYL, at 37.

As noted earlier, an atom is ionized when an electron is
ejected from its orbit and expelled from the atom. As
ionizing radiation passes through human tissue, it can
transfer its energy along the tracks of the charged particles
to the atoms and molecules of the tissue and ionize the
atoms and molecules of that tissue. CHERNOBYL , at 37.

There are two mechanisms by which ionizing radiation
can alter human cells. LAMARSH, at 409. First, the ionization
can directly alter biological structures by the disruption or
breakage of molecules. Id.; ICRP 60, at 96. Second,
biological structures can be altered indirectly by chemical
changes set in motion by the transfers of energy to the
medium as the ions pass through the molecular structure
of human tissue. ICRP 60, at 96. Most of this energy
transfer takes place in the water of our cells simply because
water is the major component of the human body. 42 MEDICAL
EFFECTS, at 13; BEIR V, at 12. When an ionizing particle
passes through a water molecule, it may ionize it and
produce an ionized water molecule, H2O+, and an electron.
The electron can be trapped and produce a hydrated
electron, eaq. BEIR V, at 12. However, the ionized water
molecule, H2O+, reacts with another water molecule to
produce a free radical called the "hydroxyl radical, OH." Id.43
This particular free-radical is very reactive because it has
an unpaired electron and seeks to pair its electron in order
to stabilize itself. BEIR V, at 13. At high initial
concentrations, back reactions occur which produce
hydrogen molecules, hydrogen peroxide and water. Id.
However, the water molecule is not always ionized in this
process. It can also simply become excited and break up
into the hydrogen radical, H., and the hydroxyl radical,
OH.. Id.

The result of this chemical process is the formation of the
_________________________________________________________________

42. Human cells are made up of 70% water. MEDICAL EFFECTS, at 13.

43. A free radical is an atom or molecule that has a single unpaired
electron. MEDICAL EFFECTS, at 13.

                                36
three highly reactive species: the hydrated or aqueous
electron, eaq, the hydroxyl radical, OH., and the hydrogen
radical, H.. Id. All three are highly reactive and can damage
the molecular structure of human cells. Id. Free radicals
are produced almost immediately after an energy transfer.44
They move rapidly in the medium, can travel some distance
from the site of the original event that creates them, and
they can cause chemical changes in the medium. Id.
However, even though free radicals are highly reactive and
potentially very dangerous to the structure of cells in
human tissue most recombine to form oxygen and water in
about 10-5 seconds without causing any injury. MEDICAL
EFFECTS, at 13.

Ionization radiation can damage cells whether the
radiation results directly from the electrons set in motion or
indirectly by the chemical production of free radicals.
CHERNOBYL, at 37. A great deal of evidence suggests that
DNA is the principal target in an irradiated cell, and is the
most critical site for lethal damage. ICRP 60, at 96; BEIR V,
at 13. DNA is believed to be the "critical cellular component
injured," as low doses of radiation. MEDICAL EFFECTS, at 16.
The random character of energy absorption events caused
by ionizing radiation can damage vital parts of DNA in
several ways including single-strand or double-strand
breaks in the DNA molecule. ICRP, at 96. However, it has
been postulated that the majority of DNA strand breaks are
not due to the direct effects of ionizing radiation, but rather
are caused by the hydroxyl radical. MEDICAL EFFECTS, at 14;
see also BEIR V, at 14. Irradiation can also cause a
number of recombinational changes to cells. ICRP 60, at
96.

Not all irradiation-caused damage to DNA is harmful.
Cells have evolved complex repair systems and when a
single-strand break occurs, it is quite possible that the site
of the damage can be identified and the break very quickly
repaired. Id.; CHERNOBYL, at 38. In such a case, the DNA
structure is returned to its original form, and there is no
long term cellular consequence. ICRP 60, at 96. For
example, if ionizing radiation affects a single protein within
_________________________________________________________________

44. A They are created in about 10-12   seconds. BEIR V, at 13.

                               37
a cell, the cell can simply produce a new protein and there
is no functional change. CHERNOBYL at 37. Alternatively, the
repair may not return to DNA to its original form, but DNA
integrity may be retained. Id.

While it is possible for double strand breaks in DNA to be
repaired, the consequences of a double strand break are
very serious. ICRP 60, at 96. Chromosomal aberrations are
a result of DNA that is damaged by irradiation. These
aberrations can be measured quantitatively as a function of
absorbed dose. Id. at 97. The outcome could be cell
reproductive death, misrepair reflected in a mutation or
extensive gene deletion. Id. at 96.

If cellular damage is not repaired, it may prevent the cell
from surviving or reproducing, or it may result in a viable
but modified cell. CHERNOBYL, at 38. The two outcomes have
severe, and different, implications for the human body,
leading to either "deterministic" or "stochastic" effects. Id.
Deterministic effects are entirely predictable and their
severity is an inevitable consequence of a given dose.
LAMARSH, at 409. Stochastic effects are those that occur at
random, i.e., they are of an aleatory or statistical nature.
CHERNOBYL, at 38. Thus, stochastic effects are those whose
probability of occurrence, as opposed to severity, is
determined by dose. LAMARSH, at 409.

i. Deterministic Effects.

Deterministic effects result when an organism can no
longer compensate for the extent of dead cells by
proliferating viable cells. ICRP 60, at 99. Cell death or cell
killing is the main process involved in deterministic effects.
Id. Unless the dose is very high, most types of cells are not
immediately killed, but continue to function until they
attempt to divide. Id. The attempt to divide will fail,
probably because of severe chromosome damage, and the
cell will die.45 Id. Cell death usually becomes apparent
within a few hours or days after irradiation. Id. at 97.
_________________________________________________________________

45. Although individual cell death in a tissue is stochastic, the total
effect of the death of a high number of cells in a tissue is
deterministic.
ICRP 60, at 99; CHERNOBYL, at 38.

                               38
Cell death is not always life threatening because most
body organs and tissues are unaffected by the loss of even
a substantial number of cells. CHERNOBYL, at 38. It is only
when a tissue or organ absorbs a certain threshold dose
high enough to kill or impair the reproduction of a
significant fraction of vital cells within the tissue or organ
that there is a clinically detectable impairment of function.
ICRP 60, at 99. If enough cells are killed, the function of
the tissue or organ is impaired. Id. at 97. In extreme cases
the organism dies. Id. The severity of the effect is dependent
on the dose. Id. Thus, the likelihood of a deterministic effect
is zero at a dose lower than some threshold, but the
likelihood increases to certainty above such a threshold
dose, with the severity of the harm increasing with dose.
CHERNOBYL, at 38-39.

Cells that divide rapidly are very sensitive to radiation
and it is in these cells that the damage from radiation
appears to be the greatest. KNIEF, at 75. Such cells include
lymphocytes, immature bone marrow cells and intestinal
epithelium. Slightly less sensitive cells include those of the
lens of the eye and the linings of the stomach, esophagus,
mouth and skin. Cells of intermediate sensitivity include
those of the liver, kidneys, lungs, thyroid andfibrous
tissue. Cells that divide slowly or not at all are the least
sensitive to radiation. CHERNOBYL, at 39. These include
mature red blood cells, muscle connective tissue as well as
bone, cartilage and nervous tissue. Id. Thus, if a person
receives a whole body absorbed dose of 1 Gy or 100 rad,
generally only those cells with very high sensitivity would
be killed. However, as the whole body absorbed dose is
increased, additional cells and organs could die and
thereby alter the person's clinical presentation. Id.
Obviously, if exposure to ionizing radiation results in
damage to vital organs or tissues, it may well be fatal. Id.

The likelihood of a deterministic effect is practically zero
for absorbed doses below 1 Gy or 100 rad. Above that
absorbed dose level, deterministic effects occur. Some
examples of deterministic effects are erythema, bone

                               39
marrow depression, radiation cataracts, sterility, and acute
radiation syndrome. Id.; MEDICAL EFFECTS, at 280.46

Clinically significant bone marrow depression has a
threshold for acute absorbed doses of about 0.5 Gy or 50
rad and for protracted exposure over many years of about
0.4 Gy or 40 rad per year. CHERNOBYL, at 39. Absent
appropriate medical care, bone marrow depression will
result in half of the people in a heterogeneous population
who are acutely exposed to a dose of about 3 to 5 Gy or
300 to 500 rad.47 Id. The threshold for opacities significant
enough to cause vision impairment (which occurs after
some delay) appears to be in the range of 2 to 10 Gy or 200
to 1000 rad for an acute exposure to x-rays or gamma (g)
rays. The threshold for chronic exposure over many years
is thought to be about 0.15 Gy or 15 rad per year. Id.

Death is almost certainly the deterministic effect for an
individual exposed to a whole body dose of about 6 Gy or
600 rad or higher over a short period. Id. A 3 Gy or 300 rad
dose would be lethal for half of an irradiated population
who receive little or no medical care, the so called"median
lethal dose". Id. However, it has been postulated that for
people in good health who receive very intensive medical
treatment, the median lethal dose may be from 5 Gy or 500
rad to as high as 9 Gy or 900 rad. Id.
_________________________________________________________________

46. The threshold for temporary sterility in men for a single absorbed
dose to the testis is about 0.15 Gy or 15 rad and the threshold under
conditions of prolonged exposure is about 0.4 Gy or 40 rad. CHERNOBYL,
at 39. The threshold for permanent sterility is 3.5 to 6 Gy or 350 to 600
rad for acute exposure and 2 Gy or 200 rad for prolonged exposure. Id.
The threshold for permanent sterility in women is an acute absorbed
dose between 2.5 to 6 Gy or 250 to 600 rad or a protracted dose over
many years of about 0.22 Gy or 22 rad. Id.

47. The estimate of the number of people who would die within a certain
number of days without medical attention following a significant whole
body absorbed dose is called the "lethal dose estimate" and, in this
example, would be expressed as "LD50/60", meaning "Lethal Dose for
50% of the population within 60 days without medical attention." KNIEF,
at 76.

                               40
ii. Stochastic Effects.

Stochastic effects are those which result when an
irradiated cell is modified rather than killed. C HERNOBYL, at
39. Even at very low doses it is possible that ionizing
radiation may deposit sufficient energy into a cell to modify
it. ICRP 60, at 98. Thus, there is a finite possibility for the
occurrence of a stochastic event even at very small doses.
Id. Consequently, it is assumed that there is no threshold
for the initiation of a stochastic event. Id. , at 98; MEDICAL
EFFECTS, at 73. Put another way, it is believed that
stochastic effects can occur even at the lowest doses and,
therefore, the possibility of a stochastic effect has to be
taken into account at all doses. ICRP 60, at 67. The
probability that cancer will result from radiation increases
proportionally with dose. ICRP 60, at 69. CHERNOBYL, at 40.
However, it is currently believed that there is no threshold
dose below which the probability of cancer induction is
zero. ICRP 60, at 69; CHERNOBYL, at 40. It is presumed that
any transformed cell can become cancerous and become a
malignant tumor. CHERNOBYL, at 40.

There are two generally recognized types of stochastic
events. The first can occur in somatic cells and may result
in the induction of cancer in the exposed person. The
second can occur in cells of the germinal tissue and may
result in hereditary disorders in the descendants of the
irradiated.48 CHERNOBYL, at 39-40; ICRP 60, at 69, 106-07.
However, even though hereditary stochastic effects have
been demonstrated on highly irradiated mice, CHERNOBYL, at
42, hereditary stochastic effects have not yet been clearly
demonstrated in humans. BEIR V, at 4. Thus, any such
effects are based on extrapolation from mice to humans.49
_________________________________________________________________

48. "There are approximately 4 #46# 1013 cells in the average adult
person.
. . . [and they] are divided into two broad classes: somatic cells and
germ
cells. Almost all of the cells in the body are somatic cells. These are
the
cells that make up the organs, tissues, and other body structures. The
germ cells, which are also called "gametes", function only in
reproduction." LAMARSH, at 406.

49. Such extrapolation has led to the estimate that at least 1 Gy or 100
rad of low-dose, low LET radiation is necessary to have any hereditary
stochastic effect on humans. BEIR V, at 4.

                               41
Genetic studies of the almost 15,000 children of the
survivors of the atomic bombing in Japan have not yielded
evidence of a statistically significant increase in severe
hereditary effects. CHERNOBYL, at 42; BEIR V, at 4. Of
course, the difficulties encountered in studying the
probability of hereditary effects are formidable and include
the need to monitor very large numbers of people in
irradiated and controlled populations. The difficulty is
increased because hereditary effects caused by radiation
may be indistinguishable from hereditary disease due to
other causes. CHERNOBYL, at 42.

It is cancer induction -- the first stochastic event -- that
it as issue here. The cell modification caused by ionizing
radiation is presumably the result of specific molecular
DNA changes by a process known as "neoplastic
transformation." It is assumed that there is no threshold for
the induction of the molecular changes at the DNA site.
ICRP 60, at 97, 107. The potential for unlimited cellular
proliferation characteristically results from molecular
changes. Id., at 107. Nevertheless, this change alone does
not result in a malignant transformation because other
changes occur in a malignant transformation. Id.
Carcinogenesis is currently believed to be a multistep
process requiring two or more intracellular events to
transform a normal cell into a cancer cell. BEIR V, at 135.
The changes that occur are believed to proceed
sequentially. ICRP 60, at 97. The initial events in the
production of a cell or cells with the potential to develop
into a cancer are known as "initiation". Id. The initiated cell
or cells must undergo further changes, usually after a long
time and possibly after stimulation by a promoting
substance or catalyst, before becoming a cell with
malignant potential. Id. Thereafter, the division and
multiplication of such cells gives rise to an occult tumor in
the "progression" stage. Id. at 97-98. "Progression" refers to
the proliferation of a subpopulation of cells within a tumor.
BEIR V, at 137. This subpopulation expands and overgrows
the less aggressive cells. Id. The carcinogenic process,
includes the growth of a primary cancer to a detectable size
(e. g., about 1 cm in diameter and containing billions of
cells). In humans it can take many years for such a tumor
to spread to other tissues. ICRP 60, at 98.

                               42
The period between exposure to radiation and possible
detection of a resulting cancer is called the "latency period".
Id. at 107. By way of example, the median latency period
for induced leukemia may be about 8 years. The latency
period for many induced solid tumors, such as tumors of
the breast or lung. Id. The "minimum latency period" is the
shortest time in which a specified radiation-induced tumor
is believed to occur after exposure. Id. It is about two years
for acute myeloid leukemia, and between 5 and 10 years for
other types of cancers. Id.

Significantly, the severity of a cancer does not depend on
the level of the dose that triggered it. ICRP 60, at 60;
CHERNOBYL, at 40. The mathematical model used to describe
radiation induced cancer is the "linear risk model". BEIR V,
at 4; CHERNOBYL, at 40. It is expressed as y = ax, where y is
the incidence of excess cancer, a is a constant, and x is the
dose. MEDICAL EFFECTS, at 81. The linear risk model posits
that each time energy is deposited in a cell or tissue, there
is a probability of the induction of cancer. Id. Thus, the
effect of each small dose is additive, and therefore
spreading a given dose out over time does not reduce the
ultimate risk. Id.

Although there is scientific consensus that ionizing
radiation can cause cancer, ionizing radiation, is not
currently known to leave a tell-tale marker in those cells
which subsequently become malignant. NATIONAL COUNCIL ON
RADIATION PROTECTION AND MEASUREMENTS, NCRP STATEMENT NO.
7, THE PROBABILITY THAT A PARTICULAR MALIGNANCY MAY HAVE
BEEN CAUSED BY A SPECIFIED IRRADIATION 1 (1992) (hereinafter
"NCRP 7"). Medical examinations and laboratory tests can
determine the type and extent of a cancer, suggest an
optimal treatment, and provide a likely prognosis, but they
rarely (if ever) provide definite information as to its cause.
Id. Consequently, medical evaluation, by itself, can neither
prove nor disprove that a specific malignancy was caused
by a specific radiation exposure. Id. Therefore, the primary
basis to link specific cancers with specific radiation
exposures is data that has been collected regarding the
increased frequency of malignancies following exposure to
ionizing radiation. Id. In other words, causation can only be
established (if at all) from epidemiological studies of

                               43
populations exposed to ionizing radiation. Id.; LAMARSH, at
413.

However, the task of establishing causation is greatly
complicated by the reality that a given percentage of a
defined population will contract cancer even absent any
exposure to ionizing radiation. In industrialized countries
where the life expectancy averages about 70 years, about
30% of the population will develop cancer and about 20%
of the population will die of cancer. CHERNOBYL , at 42. It is
estimated that if 100,000 persons with an age and sex
distribution typical of the United States are exposed to a
whole body dose of 0.1 Sv and are followed over their
lifetimes, between 770-810 people would develop fatal
cancers in excess of the normal incidence. BEIR V, at 6.

6. Radiation in the Environment.

The inquiry into cause is further complicated by the fact
that radiation is a "constituent element" of our
environment, and mankind has been exposed to it since
our first appearance on this planet. CHERNOBYL , at 23.
Obviously, natural environmental radiation has been, and
continues to be, augmented by man-made radiation.
Consequently, "the radiation environment of today differs
from that of yesterday, and it will continue to be
transformed in the future." Id. The total average annual
dose, from both natural radiation and man-made radiation,
is 3.6 mSv or 360 mrem. BEIR V, at 18.

i. Natural Radiation.

There are two major sources of natural radiation. These
are cosmic radiation and terrestrial radiation. L AMARSH, at
427. Cosmic radiation is highly energetic radiation that
bombards the earth from outer space. Terrestrial radiation
originates in radionuclides found in the earth and in our
own bodies. Id. Together, cosmic and terrestrial radiation
deliver the highest radiation dose that people normally
receive.50 CHERNOBYL, at 23.
_________________________________________________________________

50. The average annual dose of natural radiation is 2.4 millisieverts
(mSv) or 240 millirems (mrems). Natural background radiation levels
vary widely throughout the world. The dose of 2.4 mSv or 240 mrems is

                               44
Cosmic radiation consists primarily of a highly-energetic
mixture of protons (about 87%), alpha (a) particles (about
11 percent), and a trace of heavier nuclei (about 1%) and
electrons (about 1%). LAMARSH, at 427. However, the
atmosphere acts as a shield, greatly weakening cosmic rays
before they reach earth. MEDICAL EFFECTS, at 32. About 26
cosmogenic radionuclides have been identified. They are
produced by the action of cosmic radiation. LAMARSH, at 429.
However, of the 26, only tritium (3H)51, beryllium-7 (7Be),
sodium-22 (22Na) and carbon-14 (14C), contribute
appreciably to irradiation, MEDICAL EFFECTS, at 32, and only
carbon-14 (14C), is responsible for significant radiation
doses. LAMARSH, at 429. Fortunately, carbon-14 is a
relatively short-lived radionuclide.52 It primarily results from
the atmospheric interaction of thermalized cosmic ray
neutrons and nitrogen. Id. The concentration of 14C is about
the same in all living species, i.e., 7.5 picocuries per gram
of carbon. Id. Because approximately 18% by weight of the
human body is carbon, 14C contributes an estimated
annual dose of 0.007 mSv or 0.7 mrems. Id.

The average dose of cosmic radiation at or near sea level
is 0.37 mSv per year or 37 mrems per year. Id.; CHERNOBYL,
at 23. However, the dose rate increases with altitude,
doubling about every 1500 meters. CHERNOBYL, at 23.
Consequently, people living at high altitudes53 may have an
average annual dose level reaching 1 mSV or 100 mrems.
Id.

Terrestrial radiation accounts for as much as 85% of the
_________________________________________________________________

a world-wide average. However, it has been estimated that the average
annual dose in the United States from natural background radiation is
higher, around 3 mSv or 300 mrems, because of a reevaluation of the
quantities and effects of radon gas. KNIEF, at 88. For a brief discussion
of radon gas, see below.

51. Tritium is a radioactive isotope of hydrogen. There is another isotope
of hydrogen call deuterium (2H) or heavy hydrogen. Deuterium is not
radioactive. LAMARSH, at 8; MEDICAL EFFECTS, at 391, 396.

52. T1/2 = 5730 years.

53. For example, Denver, Colorado or Bogota, Colombia. CHERNOBYL, at
23.

                               45
total average annual dose of natural radiation, i.e., a little
over 2.0 mSv or 200 mrems annually Id. There are
approximately 340 naturally-occurring nuclides on earth,
and of these, about 70 are radioactive. LAMARSH , at 429.
They are called primordial radionuclides because they have
existed in the earth's crust since the earth was formed. Id.
Those now present on earth have half-lives comparable to
the age of the universe. MEDICAL EFFECTS, at 33. Accordingly,
primordial radionuclides with half-lives of less than about
108 years can no longer be detected. Id. Primordial
radionuclides with half-lives of more than 1010 years have
decayed very little up to now. Id.

Primordial radionuclides produce secondary
radionuclides through the process of radioactive decay.
There are three distinct chains of primordial radionuclides:
(1) the uranium series, which originates with 238U; (2) the
thorium series which originates with 232 Th; and (3) the
actinium series, which originates with 235 U. Together, the
parent of each chain and its respective daughter products
contribute significantly to terrestrial irradiation. Id.

Uranium is found in various quantities in most rocks and
soils, and it is the main source of radiation exposure to
people out-of-doors. CHERNOBYL, at 23. The uranium isotopes
are alpha (a) particle emitters and, therefore, they do not
contribute to gamma (g) ray exposure.54 MEDICAL EFFECTS, at
33. Since uranium isotopes are generally present in low
concentrations, they do not contribute significantly to the
internal alpha (a) ray dose delivered to humans. Id.
However, since these isotopes are found in soil and
fertilizers, they migrate into our food chain, and therefore,
into our tissue. Id. at 35.

Another significant source of terrestrial radiation
exposure is radium-226 (226Ra)-- an isotope which
originates in the uranium series -- and its daughter
_________________________________________________________________

54. Naturally occurring uranium consists of threeisotopes, 234U, 235U
and 238U. Uranium-238, the parent of the uranium series is the most
abundant isotope, present in the amount of 99.28%, and it is in
equilibrium with 234U, which is present in the amount of 0.0058%.
Uranium-235, present in the amount of 0.71%, is the parent of the
actinium series. MEDICAL EFFECTS , at 33.

                               46
products. Radium-226, with a half-life of 1622 years, is an
alpha (a) emitter and is present in all rocks, soils and
water. Id. Radium is chemically similar to calcium and it
passes through the food chain into humans because plants
absorb it from the soil.55 The annual dose attributable to
the intake of 226Ra is 7 microsieverts (Sv) or 0.7 mrem. Id.
at 36.

Approximately 95% of the world's people live in areas
where the annual average dose from outdoor external
radiation sources is about 0.4 mSv or 40 mrems.
CHERNOBYL, at 24. However, there are areas in the world
where people are exposed to very high levels of terrestrial
radiation. For example, thorium-rich monozite sands in
certain areas of Brazil and India also have exceptionally
high levels of irradiation. LAMARSH, at 429.56

Radium-226 is also an important source of terrestrial
radiation exposure because it decays to radon-222 (222Rn),
a noble gas radionuclide with a half-life of 3.8 days that
emits alpha (a) particles and contributes to gamma (g)
radiation through its gamma-emitting descendants. Id.
Radon is an odorless, colorless, nonreactive gas that poses
no significant biological threat. Id. Alpha (a) particles
emitted by radon outside the body do not penetrate skin.
Id. However, the daughter elements formed as radon decays
can be a significant source of natural irradiation and
potential biological damage. CHERNOBYL, at 24. Once inhaled,
the radon daughters may be deposited in the tracheo-
bronchial tree. Id. Some of the radon daughters -- the
polonium isotopes, 218 (radon A) and 214 (radon C 1) --
emit alpha (a) particles. 218Po (radon A) provides the major
alpha (a) particle dose to the tracheo-bronchial tree, and it
therefore poses an increased risk of lung cancer. C HERNOBYL,
at 24.
_________________________________________________________________

55. In the human body, 70% to 90% of radium is found in bone. MEDICAL
EFFECTS, at 35.

56. Similarly, in Guarapari, Meaipe and Pocos de Caldas in Brazil,
exposure dose rates can be 100 times the norm, and in the coastal areas
of Kerala and Tamil Nadu in India, exposure rates can be 1000 times
higher than the norm. CHERNOBYL, at 24.

                               47
Because it is a noble gas, radon diffuses from its point of
origin. LAMARSH, at 430. Moreover, because it is the
immediate daughter product of the decay of radium-226 (226
Ra), it can be present in radium-bearing rocks, soils and
home construction materials. Id at 429-30. Radon enters
buildings primarily through the underlying and
surrounding soils and, secondarily from building materials,
outdoor air, tap water and natural gas. CHERNOBYL, at 24.
Since concentration increases in enclosed spaces, radon
concentration is much higher indoors than outdoors.
MEDICAL EFFECTS, at 37-38. Radon is the largest contributor
to terrestrial radiation because people spend most of their
time indoors.57 Levels of radon in the air vary from place to
place, season to season, day to day and hour to hour. Id.

Both lead-210 (210Pb) and polonium-210 (210Po), which, as
noted above, are decay products of radon-222 (222Rn), are
introduced into the human body through inhalation as well
as through the food chain. LAMARSH, at 429-30. 222Rn is a
noble gas and therefore, tends to diffuse into the
atmosphere where it can travel large distances before
decaying into 210Pb. Id. at 430. 210Pb is not inert and
attaches to dust and moisture particles in the atmosphere
soon after it is formed. Consequently, it can be inhaled
directly into the body or fall onto leafy vegetables or pasture
grasses from where it can enter the food chain. Id. at 430,
433. Lead-210 does not lead to significant internal
radiation doses because it is a rather weak beta (b) particle
emitter. However, its daughter product, 210Po, is a powerful,
highly-energetic alpha (a) particle emitter and it provides
very significant doses of radiation. Id. at 431.

Because both radionuclides can enter the body through
ingestion, internal radiation exposure is influenced by
dietary patterns. CHERNOBYL, at 24. For example, both
radionuclides are present in seafood thus, in countries
such as Japan, where seafood is a dietary staple, annual
intakes of both radionuclides are significantly higher than
in countries where seafood is not a staple. Id. Both
_________________________________________________________________

57. It is responsible for more than half of the natural radiation we are
exposed to, i.e., 1.3 mSv per year or 130 mrems per year. CHERNOBYL, at
24.

                               48
radionuclides concentrate in lichens. Accordingly, people in
the extreme northern hemisphere who eat the meat of
animals that graze on lichens (caribou and reindeer) have
levels about ten times higher than the norm. Id. Both 210Pb
and 210Po are found on broadleaf tobacco plants, Id. at 433.
Both of these radionuclides have also been detected in
commercial tobacco products and in cigarette smoke.
CHERNOBYL, at 24.

There is a dispute within the scientific community as to
whether background radiation produces stochastic effects.
The International Commission on Radiological Protection
assumes that stochastic effects may be induced by natural
radiation and man-made radiation. ICRP 60, at 93. It has
been inferred that about 3% of cancer deaths each year in
the United States are attributable to background radiation,
with 1.5 to 2% due to natural radiation, 0.5% to medical
uses and 1% or less to occupational sources. See Luis
Felipe Fajardo, Ionizing Radiation and Neoplasia, in NEW
CONCEPTS IN NEOPLASIA AS APPLIED TO DIAGNOSTIC PATHOLOGY 99
(Cecilia M. Fenoglio-Preiser, Ronald S. Weinstein and
Nathan Kaufman, eds., 1986). However, it has also been
reported that natural background has not yet been proven
to be cancer inducing, and, some scientists claim that
natural background radiation does not cause cancer. Id.

ii. Man made Radiation.

Here, of course, we are most directly concerned with
radiation from the nuclear power plant at TMI. It is
undisputed that the production of electricity by nuclear
power can add to the radioactivity in our environment.
Irradiation occurs in the production of electricity, and in all
stages of the fuel cycle, i.e., mining, fuel fabrication,
transportation, reactor operation and reprocessing
CHERNOBYL, at 26-27. However, under normal
circumstances, and without considering the effect of
nuclear power plant accidents, the overall impact of nuclear
power generation on the total population is reported to be
very small. MEDICAL EFFECTS, at 45.

There are three major sources of man-made radiation
other than nuclear power plants. These are: industrial
processes other than nuclear power generation that also

                               49
use radionuclides, medical irradiation, and nuclear
weapons testing. CHERNOBYL, at 24.

Medical irradiation is generally divided into three
categories: (1) diagnostic x-ray examinations; (2) the use of
radiopharmaceuticals in nuclear medicine; (3) therapeutic
applications of radiation. MEDICAL E FFECTS, at 47.58

Nuclear weapons testing occurs either above ground
("atmospheric testing"), or underground.59 Radionuclides
released in atmospheric testing can enter the body directly
or be deposited on the earth's surface from whence they
may later be absorbed via the food chain, or be absorbed
through by way of external radiation. MEDICAL EFFECTS, at
44.

Generally, estimates of human exposure to fallout are
more concerned with atmospheric (and more particularly
stratospheric), fallout than with local or tropospheric fallout
because radionuclides in the stratosphere result in fallout
worldwide. Id. In fact, stratospheric particulate fallout
accounts for most of mankind's worldwide exposure to
fission products. Id. Fallout consists of numerous
radioactive byproducts of atomic reactions. However, only
four of these have half-lives of sufficient length to be of
significant concern to present and future populations: 14C,
with a half-life of 5730 years; 137Cs and 90Sr, both with a
half-life of 30 years; and 3H, with a half-life of 12 years.
CHERNOBYL, at 25. 14C provides almost two-thirds of the dose
exposure because of the relatively short half-lives of the
other three radionuclides. Id. The average annual dose to
individuals from atmospheric testing is 0.01 mSv or 1
_________________________________________________________________

58. The average annual dose due to medical irradiation is between 0.4
and 1 mSv or 40 to 100 mrems. CHERNOBYL, at 47. Of the three categories
of medical irradiation, diagnostic x-ray examinations account for almost
95% of the total dose received. Id.

59. Atmospheric testing began in 1945. From then until 1980 there were
more than 400 nuclear weapons tested in the atmosphere. CHERNOBYL, at
25. In 1963, the United States, the United Kingdom, and the former
USSR entered into the Partial Test Ban Treaty, and undertook to cease
atmospheric testing. However, France and China continued atmospheric
testing. Id. All of the atmospheric tests released significant amounts of
radioactive material into the environment. CHERNOBYL, at 47.

                               50
mrems. Id. There have been approximately 1300
underground nuclear weapons tests. MEDICAL EFFECTS, at 44.
However, a well-contained underground explosion delivers
little, if any, radionuclides to the environment, except for
occasional venting. Id.

Industrial processes, such as electricity production,
mining, and the use of certain building materials and
fertilizers produce above average concentrations of natural
radionuclides. CHERNOBYL, at 25. Coal contains more
radionuclides than other fossil fuels and burning coal
produces a large amount of particulate emissions. M EDICAL
EFFECTS, at 39. Other sources of industrial irradiation
include certain consumer products, such as luminous
timepieces, electronic and electrical devices, video display
terminals, antistatic devices, and smoke detectors. MEDICAL
EFFECTS, at 42. However, tobacco products probably
contribute the greatest radiation dose of all consumer
products. Id. at 43. It has been postulated that the
radionuclides 210Pb and 210Po are responsible for the high
incidence of lung cancer in smokers. BEIR V, at 19;
LAMARSH, at 433.

It is generally conceded that atmospheric weapons testing
has contributed more to man-made radiation than nuclear
power plants. Id. at 45. On average, the annual dose from
all facets of the nuclear fuel cycle is less than 0.1% of that
from natural radiation, CHERNOBYL, at 26, or less than 10
mSv or 1 mrem a year. KNIEF, at 88. In fact, it has been
postulated that atmospheric releases of radionuclides from
fossil fuel plants, especially coal plants without scrubber
systems, may be greater than the releases of radionuclides
from nuclear power plants. MEDICAL E FFECTS, at 45.

Nevertheless, it is beyond dispute that nuclear power
plants in general, and nuclear accidents in particular, can
release harmful radioactivity into the environment.
Irradiation occurs not only in the production of electricity
but in all stages of the fuel cycle, i.e., mining, fuel
fabrication, transportation, reactor operation and
reprocessing CHERNOBYL, at 26-27.60
_________________________________________________________________

60. Under normal circumstances, and without considering the effect of
nuclear power plant accidents, the overall impact of nuclear power
generation on the total population is reported to be very small. MEDICAL
EFFECTS, at 45.

                               51
61. Charged particles and gamma (g) rays can also induce fission, but
they are not significant for our purposes because neutron induced
fission is the basis of commercial nuclear power, KNIEF, at 41, and it is
that fission that occurred at TMI.
Accordingly, before proceeding with our discussion of the
District Court's application of Daubert to the expert
testimony that was offered to prove that TMI-2 released
radiation that caused the Trial Plaintiffs' neoplasms we will
briefly discuss the operation of a nuclear power plant in an
effort to better determine if Trial Plaintiffs proffered
sufficient evidence to connect their injuries to the nuclear
reactions that took place inside the nuclear generator at
TMI-2. For purposes of assessing the Daubert challenges to
the experts in this case, we will limit our discussion of
nuclear fission to reactions initiated by neutrons.61

                               52
Volume 2 of 4

Filed November 2, 1999

UNITED STATES COURT OF APPEALS
FOR THE THIRD CIRCUIT

Nos. 96-7623/7624/7625

IN RE: TMI LITIGATION

LORI DOLAN; JOSEPH GAUGHAN; RONALD
WARD; ESTATE OF PEARL HICKERNELL;
KENNETH PUTT; ESTATE OF ETHELDA HILT;
PAULA OBERCASH; JOLENE PETERSON; ESTATE OF
GARY VILLELLA; ESTATE OF LEO BEAM,

       Appellants No. 96-7623

IN RE: TMI LITIGATION

ALL PLAINTIFFS EXCEPT LORI DOLAN, JOSEPH
GAUGHAN, RONALD WARD, ESTATE OF PEARL
HICKERNELL, KENNETH PUTT, ESTATE OF ETHELDA
HILT, PAULA OBERCASH, JOLENE PETERSON, ESTATE
OF GARY VILLELLA AND ESTATE OF LEO BEAM,

       Appellants No. 96-7624

IN RE: TMI LITIGATION

ALL PLAINTIFFS; ARNOLD LEVIN; LAURENCE
BERMAN; LEE SWARTZ

       Appellants No. 96-7625

ON APPEAL FROM THE UNITED STATES DISTRICT
COURT FOR THE MIDDLE DISTRICT OF PENNSYLVANIA
(Civil No. 88-cv-01452)
(District Judge: Honorable Sylvia H. Rambo)
ARGUED: June 27, 1997

Before: GREENBERG and McKEE, Circuit Judges, and
GREENAWAY, District Judge*

(Opinion filed: November 2, 1999)

IV. NUCLEAR ENGINEERING

A. Nuclear Reaction.62

The bulk of electricity generated in the United States is
the result of thermal energy (i.e., heat) produced in either
fossil-fueled boilers or nuclear power plants. ANTHONY V.
NERO, JR., A GUIDEBOOKTO NUCLEAR REACTORS 3 (1979).
Nuclear power plants generate energy through nuclear
fission. Id. Nuclear fission provides nearly one hundred
million times as much energy as the burning of one carbon
atom of fossil fuel. KNIEF, at 4. Fission therefore has obvious
advantages over fossil-fuel based energy production. It has
been estimated that the complete fission of just one pound
of uranium would release approximately the same amount
of energy as the combustion of 6,000 barrels of oil or 1,000
tons of high-quality coal. NERO, at 4. However, the major
disadvantage of the fission process is now painfully
obvious. It requires mankind to harness and control one of
the most awesome physical powers in the universe. In
addition, potentially deadly radioactive materials are
produced in the process. KNIEF, at 4

Neutron interactions with nuclei are possible because the
absence of a charge allows a neutron to approach a nucleus
without repulsion from an opposing force. BENNETT, at 23.
The important reactions occur at relatively low energies and
include "elastic scattering", "inelastic scattering", "neutron
capture" and fission. BODANSKY at 46. Chance determines
_________________________________________________________________

* The Honorable Joseph A. Greenaway, Jr., United States District Court
Judge for the District of New Jersey, sitting by designation.

62. The general term "nuclear reaction" describes any of a wide number
of interactions involving nuclei. BODANSKY, at 46.

                               54
which of these reactions occur for a given neutron. Id. at
48.

In elastic scattering, a neutron and nucleus collide
without any change in the structure of the target nucleus.
Id. It is, therefore, like "the collision of two billiard balls of
unequal mass." BENNET, at 23. Although the structure of the
nucleus is unchanged in elastic scattering, the laws of
motion cause the neutron to change direction and speed
and the nucleus recoils. BODANSKY, at 47. The total kinetic
energy of the system is unchanged, but some of the
neutron's energy is transferred to the target nucleus. Id.
Elastic scattering can occur with any target nucleus, but in
nuclear reactors it is most significant when the target
nucleus is relatively light, and the loss of kinetic energy is,
therefore, relatively large. Id. In that scenario, elastic
scattering effectively reduces the energy of the neutrons
without depleting their number.

Inelastic scattering differs from elastic scattering because
the target nucleus is left in an excited state. Id. The target
nucleus decays, usually quickly, to the ground state with
the emission of gamma (g) rays. The total kinetic energy of
the neutron and the target nucleus after the scattering is
less than that of the neutron before the scattering, with the
difference equaling the energy of the gamma (g ) rays. Id. An
important characteristic of inelastic scattering is that
neutrons lose on average much more energy per collision
than they do in elastic scattering. BENNET, at 28.

In neutron capture, which occurs in the first stage of
many reactions, the neutron combines with the target
nucleus to form an excited compound nucleus. BODANSKY, at
47. The term "neutron capture" is usually restricted to
cases where the excited compound nucleus decays by the
emission of gamma rays.63 Id. The number of gamma rays
emitted in the de-excitation varies. Id.

Neutron capture can occur for almost any target nucleus
and it plays two general roles in nuclear reactors. First, it
_________________________________________________________________

63. An example is: formation: n + 238U fi 239U*
       de-excitation: 239U* fi 239U + g's

BODANSKY, at 47.

                                55
consumes neutrons that might otherwise initiatefission.
Second, it transforms nuclei produced in fission into other
nuclei. Id. Further, as will be discussed below, the reaction
is significant because it is the first step in the production
of plutonium-239 in reactors. Id.

As noted earlier, a nuclear reactor produces energy from
fission. However, fission is possible for only a very few
target nuclei, the most important being isotopes of uranium
and plutonium. Id. at 48. If an appreciablefission yield is
produced by neutron incidents upon a target nucleus, that
nuclear species is termed fissile. Id. at 61. In a typical
fission reaction, the excited compound nucleus divides into
two fragments plus several neutrons.64 Id. at 48. The energy
released in fission comes from the large kinetic energy of
the fission fragments. Id. An averagefission event produces
nearly 200 million electron volts of energy (200 MeV). KNIEF,
at 45. In contrast, approximately 2-3 electron volts (eV) of
energy is released for each carbon atom burned with
oxygen. Id. Neutrons produced by the fission event have an
average energy of 2 million electron volts (2 MeV). BENNET,
at 55. The fission fragments come to rest within about 10-3
centimeters of the fission site so that all of their energy is
converted into heat. LAMARSH, at 76. It is important to
remember that he fission products are all radioactive.
BENNET, at 30. The formation of eachfission product is
followed by a series of beta decays that continues with
successive emission of b- particles until a stable isobar is
reached. BODANSKY, at 48. In addition, gamma rays are
emitted in the de-excitation of the fission fragments,
assuming they are formed in excited states, as well as in
the de-excitation of the products of the successive b-
decays. Id..
_________________________________________________________________

64. A typical fission reaction illustrated for a 235U target is of the
general
form:

       n + 235U fi236U* fi144Ba + 89Kr +
              3n.

The products in this example are barium 144 (atomic number Z = 56),
krypton 89 (Z=36), and 3 neutrons. BODANSKY, at 48. Many other
outcomes are also possible, always subject to the condition that the
sums of the atomic numbers of the products are the same as those of
the initial system. Id. Both the 144Ba and 89Kr nuclei areradioactive. Id.

                               56
The release of significant amounts of energy fromfission
requires a chain reaction. Id. at 69. Fission forms the
backbone of the required chain reaction. NERO , at 5. Earlier,
it was noted that neutrons produced by fission in the
uranium fuel have an average energy of 2 MeV. However,
fission in uranium will not result in a chain reaction if the
neutrons interact at energies close to those in which they
were emitted. BODANSKY, at 73. Consequently, it is necessary
to reduce the energy of the neutrons from this average
energy region to a more favorable region below 1 electron
volt (eV) by elastic collisions with the nuclei of a moderator.
Id. Commonly used moderators are hydrogen in water,
deuterium in heavy water or carbon in graphite. Id. at 74.
After a sufficient number of elastic collisions with the
moderator, the neutrons have reached a low or "thermal
energy" and a chain reaction can occur. NERO , at 7.

A chain reaction is sustained by the emission of low
energy neutrons from fissioning nuclei. BODANSKY, at 50. A
nuclear reactor such as TMI-2 is "merely" the system in
which a controlled chain reaction takes place. LAMARSH, at
103. In order for a self-sustaining chain reaction to occur,
at least one of the neutrons produced in one fission event
must cause a second fission event from which one neutron
causes a third fission event, and so on. Id. at 102. Each
such generation must have more fission events than the
preceding one if a continuing and useful chain reaction is
to occur. BODANSKY, at 69.65 The condition for establishing a
chain reaction is commonly expressed as the "achievement
of criticality". Id. "Criticality" is described quantitatively in
terms of the multiplication factor, denoted by the symbol k,
LAMARSH, at 102, or the criticality factor, BODANSKY, at 69,
which is defined as the ratio of the number offissions (or
fission neutrons) in one generation divided by the number
of fissions (or fission neutrons) in the preceding generation.
_________________________________________________________________

65. The average number of neutrons emitted infission is crucial for
establishing the practicality of a chain reaction. Id. at 64. The number
of neutrons varies from event to event, ranging from 0 to about 6. Id.
Generally 2 or 3 neutrons are emitted per event. Id. The excess is
necessary because some neutrons will be lost to capture reactions and
other neutrons will leave the region where the chain reaction is to be
established. Id.

                               57
LAMARSH, at 102. A system is critical if k equals 1. Id. If k is
greater than 1, the system is "supercritical," "and a
divergent chain reaction exists in which the neutron
density and fission rate increase, possibly at an explosive
rate as in an atomic bomb." BENNET, at 54. If k is less than
1, the system is "subcritical" and the chain reaction
decreases and eventually stops. Id

In a nuclear reactor, the operator can vary the value of k
by varying the rate at which neutrons are produced within
the reactor with the rate at which they are absorbed or
disappear.66 LAMARSH, at 103. To increase the power being
produced by the reactor, the operator increases k to a value
greater than 1 so that the reactor becomes supercritical. Id.
When the desired level has been reached, the operator
adjusts k to one so that the reactor is critical and
maintains the desired level. Id. To reduce power or shut the
reactor down, the operator reduces k to less than 1, making
the reactor subcritical. Id.

Earlier, we noted that neutron capture wastes neutrons
if we consider only fission. However, neutron capture plays
an important role in reactors because through it
nonfissionable nuclei become fissile. BODANSKY, at 61, 78.
Neutron capture in thorium-232 (232Th) and uranium-238
(238U) leads, with interveningb- decays, to the production of
the fissile nuclei uranium-233 (233U) and plutonium-239
(239Pu). Id. at 61. Therefore, 232 Th and 238U are termed
fertile. Id. Where uranium is used as the fuel, plutonium-
239 (239Pu) is ultimately produced by the capture of
neutrons in fertile uranium-238 (238U). The 239Pu can be
used for the production of atomic weapons or in other
reactors. BODANSKY, at 78. It also contributes fissile material
which is consumed in the reactor before the fuel is
removed, supplementing the original fissile 235U in the fresh
fuel. Id. Essentially, through neutron capture, the fertile
nuclei become fissile nuclei enabling the nuclear reaction to
continue in the reactor.
_________________________________________________________________

66. Nuclear bombs and explosives cannot be controlled in this way and
therefore are not called reactors. LAMARSH, at 103.

                               58
B. The Operation of Nuclear Power Plant.67

At its most elementary level, a nuclear reactor is a
deceptively simple apparatus. Simply put, a nuclear power
plant produces heat energy that is converted to steam in a
boiler. Affidavit of John A. Daniel at P 17. The steam is
used to turn a turbine, which is connected to, and turns an
electrical generator that produces electrical power. Id. The
apparent simplicity of this basic operation is made even
more deceptive when one considers the awesome power of
the forces at work within nuclear reactors such as TMI-2.
However, beyond this elementary level, a nuclear power
plant is an extraordinarily complex system. The heat energy
is produced in a vessel called a "reactor," because it
contains the nuclear reactions. Id. The reactor vessel is a
steel pressure vessel with walls that are 8-1/2 inches thick,
surrounded by a concrete and steel shield over 8 feet thick.
Id. at 23.

The TMI-2 nuclear reactor at issue here was a standard
Babcock & Wilcox pressurized water reactor ("PWR").68 It
_________________________________________________________________

67. The following description is taken, for the most part, from two
sources -- the affidavit of a defense expert witness and a report
commissioned by the Nuclear Regulatory Commission. We rely on these
sources because appellants have not provided us with any evidence of
the workings of a nuclear power plant, and because the basic operation
of a nuclear power plant is not in dispute. See 927 F. Supp. at 846. The
affidavit is of John A. Daniel, a nuclear engineer who is currently a
consultant to the nuclear power industry, and can be found in the
Consolidated Appendix at 14759-14889. The government report is
MITCHELL ROGOVIN, NUCLEAR REGULATORY COMMISSION INQUIRY GROUP,
NUREG/CR-1250, TMI REPORT TO THE COMMISSIONERS AND TO THE PUBLIC AT
10-13 (1980).

68. The physical plant of a PWR nuclear power plant consists of a
reactor building, a turbine building, an auxiliary building, a fuel
handling building and a control and service building. Daniel Aff. at P 23.
The reactor vessel, pressurizer, associated piping, reactor coolant pumps
and steam generators are collectively referred to as the "reactor coolant
system" and are located in the reactor building. Id. The reactor building
is actually a large pressure vessel designed to withstand the pressure
increase which would result if there was a rupture in reactor coolant
piping. Id. at P 24. During the plant's operation, the reactor building is
kept air tight and access to the building is through personnel air locks,
similar to those used on spacecraft. Id.

                               59
used uranium dioxide (U02) as a fuel. Id. at PP 17, 18; J. A.
Daniel, Noble Gas Transport During the TMI-2 Accident
(1993) 87. The UO2 is formed into ceramic pellets, each of
which is about one-half inch in diameter. Daniel Aff. at
P 17. Fuel pellets are stacked into metal rods called "fuel
pins", which are arranged into square "fuel assemblies." Id.
The fuel assemblies are approximately twelve feet high,
contained in the reactor, and are collectively referred to as
the "reactor core". Id. The fuel assemblies contain several
control rods with instruments, some of which monitor the
reactor, and others which speed up or slow down the
reaction. Id. These control rods, contain materials with
large thermal neutron absorption capacities. BODANSKY, at
80. The rods are either inserted or withdrawn to maintain
the appropriate level of criticality, (where k equals 1), and
enable the reactor to operate at steady power for long
periods of time. BENNET, at 107-08. The reactor contains
water some of which serves to cool the reactor during the
nuclear reaction, and some of which is heated to steam by
the chain reaction. The fuel rods containing the uranium
fuel are sheathed in rods that prevent the fuel pellets from
coming into direct contact with the water in the reactor
core and are called the fuel cladding. MITCHELL ROGOVIN,
NUCLEAR REGULATORY COMMISSION INQUIRY GROUP, NUREG/CR-
1250, TMI REPORT TO THE COMMISSIONERS AND TO THE PUBLIC 10
(1980)(hereinafter "NUREG/CR-1250"). Daniel Aff. at P 17.

The nuclear reaction in the core is generated by a
neutron source which emits neutrons in a manner designed
_________________________________________________________________

The turbine, condenser and electrical generator are housed in a
concrete and steel building called the "turbine building". Id. at P 23.
The
auxiliary building contains the auxiliary systems used to process and
maintain the chemical and radiological purity of the reactor coolant. Id.
The fuel handling building houses the storage facilities for new and used
fuel. Id. After it is removed from the reactor core, the used fuel is
stored
underwater in the "spent fuel pool." Id. The auxiliary and fuel handling
buildings have redundant air filtration units which are designed to
remove filterable radioactive particles before being discharged to the
environment. Id. The plant operations personnel monitor and maintain
control of the various plant systems from a central control room located
in the control and service building. Id.

                               60
to initiate a chain reaction. Most fission products are solid
at fuel temperature, but some are gases. Id. at P 18. Some
of the fission products, especially the noble gases krypton
and xenon, migrate to the edge of the fuel pellet and collect
in the space between the fuel and the cladding. Since some
of the fission products may escape from the cladding into
the water in the reactor, the reactors are designed to
contain cooling water within its own closed loop. Id.

In a PWR of the TMI-2 type, there are three cooling
systems. Daniel Aff. at P 19. A PWR coolant system69 is a
circuit or closed loop of distilled water with a small amount
of boric acid. NUREG/CR-1250 at 10. The primary circuit,
called the "primary coolant" or "reactor coolant", circulates
water through the reactor core. Daniel Aff. at P 19. During
normal reactor operation, the water in the primary coolant
is kept at an average temperature of 575o F and pressures
high enough, (around 2200 pounds per square inch), to
keep the water from boiling to steam. NUREG/CR-1250 at
10. The water in the primary coolant circulates and
recirculates through this loop. Id. While it is circulating and
recirculating, the primary coolant water picks up heat from
the fission reaction in the reactor core and carries the heat
from the core through two "hot leg" pipes to two steam
generators. Daniel Aff. at P 19; NUREG/CR-1250 at 10. The
steam generators are tanks, approximately 35 feet tall, in
which the primary coolant water passes through a large
number of narrow tubes that transfer heat to water
contained in another, separate circuit, called the
"secondary circuit" or "feedwater loop." Daniel Aff. at P 19;
NUREG/CR-1250 at 10. The water in the secondary circuit,
called "feedwater," is maintained at a lower pressure than
the water in the primary coolant circuit, Daniel Aff. at P 19,
allowing the feedwater to boil to steam. Id.; NUREG/CR-
1250 at 10. The steam in the secondary circuit is called the
"main steam system". Daniel Aff. at P 19.

The primary coolant water, having lost some of its heat in
the secondary circuit, is then returned to the reactor core
through four pipes, known as "cold legs." NUREG/CR-1250
_________________________________________________________________

69. There are two virtually identical coolant loops in the TMI-2 reactor,
called the "A" and "B" loops. NUREG/CR-1250 at 11.

                               61
at 11. Once the primary coolant water is returned to the
reactor core, it is heated once again by the nuclear
reaction, and the cycle repeats. Id. The primary coolant
water is kept moving at high speed in the primary circuit by
four reactor coolant pumps -- enormous devices each of
which requires enough electricity for its own operation to
light a small town. Id.

At a point between the reactor and the steam generator,
there is a pipe leading to the bottom of a large vessel or
tank called a "pressurizer". NUREG/CR-1250 at 11. During
normal operation, coolant water does not circulate back
and forth through this pipe. Id. The pressurizer is normally
kept a bit more than half full of coolant water. Above the
water is a cushion, or "bubble," of steam. Id.; Daniel Aff. at
P 20. The pressurizer is a means of keeping the pressure in
the reactor coolant system relatively constant, to prevent
the reactor coolant water from boiling. NUREG/CR-1250 at
11. The steam cushion at the top of the pressurizer can be
made larger or smaller by slight heating or cooling of the
pressurizer water just beneath it. Id. When the bubble
temperature and pressure are increased, the bubble tends
to push water from the pressurizer out into the primary
reactor coolant loop, thereby increasing pressure in the
loop. Id. When the temperature and pressure in the
pressurizer are lowered, steam condenses and the bubble
shrinks. Id. Consequently, water tends to come from the
reactor coolant loop into the pressurizer, and the overall
system pressure is lowered. Id.

A relief valve, referred to as a "power-operated relief
valve" ("PORV"), is located in a pipe leading out of the top
of the pressurizer, at the top of the space normally
occupied by the steam bubble. Daniel Aff. at P 21,
NUREG/CR-1250 at 11. The PORV is designed to open
automatically when the system begins to overpressurize.
NUREG/CR-1250 at 11. Theoretically, if the pressure in the
coolant system rises very abruptly, the PORV will open,
some of the steam will rush out to a drain tank, thus
shrinking the bubble, more water will move up into the
pressurizer from the primary coolant loop, and system
pressure will decrease. Id.; Daniel Aff. at P 21. A rupture
disk is provided on the drain tank to relieve pressure if the

                               62
drain tank becomes too full. Daniel Aff. at P 21. When the
system pressure is back to normal, the PORV is supposed
to close automatically. NUREG/CR-1250 at 11. If the PORV
fails to close, there is a backup, called a "block valve".
Daniel Aff. at P 21. There are two other safety valves in
addition to the PORV. NUREG/CR-1250 at 11; Daniel Aff.
at P 21.

The heart of the secondary circuit or feedwater loop is the
steam generator. NUREG/CR-1250 at 11. After the water in
the secondary circuit is heated to steam by the hot water
from the primary coolant system, the steam moves through
the secondary circuit or feedwater loop to a steam turbine
which turns the power generator that produces the
electricity. NUREG/CR-1250 at 11. The steam then passes
through a condenser, where it is cooled and condensed into
water once again and recycled through the steam
generators. Id. at 11-12. The pipe line returning the water
from the condenser to the steam generator also contains
the condensate polishers or "demineralizers". Id. at 12. The
demineralizers are basically water softeners, that use ion
exchange resins to purify the feedwater. Id.

The condenser itself is cooled by water from the third
circuit, i.e., the cooling towers, Id. at 12; Daniel Aff. at P 19,
which are the familiar landmarks of nuclear plants. The
water in the condenser circuit, having been warmed in the
process of condensing steam back into water, is pumped up
to the cooling towers. NUREG/CR-1250 at 12. The
condenser water is thus cooled by exposure to the
atmosphere as it tumbles down a steep run of steps and
then is pumped back into the condensers. Id. The escaping
water vapor is the plume or cloud which can often be seen
coming out of the cooling tower. Id.70
_________________________________________________________________

70. During this process, chemicals may be added to the reactor coolant
to fine tune the nuclear reaction in the reactor core, and to remove any
impurities that may have collected in the coolant. Daniel Aff. at P 22.
During power operations, a small flow of reactor coolant is bled off from
the reactor coolant system and passed through a series of filters and
demineralizers. Id. If additional water is needed in the reactor coolant
system, it is added from water stored in tanks located in an auxiliary
building. Id. The system that collects water from the reactor coolant
system and adds water to the reactor coolant system is called the
"makeup and purification system". Id. Any gases collected from the
reactor coolant system are collected in waste gas decay tanks. Id.

                                63
In addition to the systems peculiar to a PWR, the TMI-2
reactor had a general safety system common to all reactors
called the "emergency core cooling system" ("ECCS"), which
is designed to supply cooling water to the hot reactor core
if there is a loss of water due to a break in the reactor
coolant system. NUREG/CR-1250 at 12. If the break is
small, the leakage flowing from the break may not be
significant and the system's internal pressure will stay
high, making it difficult for the ECCS to pump water in. Id.
Consequently, the plant has high pressure injection ("HPI")
pumps to deliver water from a large borated water storage
tank ("BWST"). Id. However, the HPI pumps are not able to
deliver enough water if the break is large. Id. Therefore, the
system has a set of low pressure injection ("LPI") pumps
that can deliver water to the core rapidly when a large pipe
break has caused the system's internal pressure to drop.
Id. The LPI pumps also draw water from the BWST. Id.

The LPI pumps also have another purpose. When a
reactor is shut down, the radioactive waste in the fuel
continues to produce a considerable, but diminishing,
amount of decay heat for days following shutdown. This
heat must be removed if the core is to be kept from melting.
Id. Even after the reactor is shut down, the accumulated
fission products continue to decay and release energy
within the reactor. LAMARSH, at 350. This fission product
decay is called "decay heat". Id. A method for handling the
decay heat and for cooling the reactor core after shutdown
must be provided or the temperature of the fuel may rise to
a point where the fuel's integrity is compromised and
fission products are released. Id.

After shutdown, the reactor is first cooled by the
continued normal operation of the steam generators until
the reactor coolant system is cooled to a temperature of
about 300$F and an internal system pressure below 400
psi. NUREG/CR-1250, at 12. Then, valves are opened to let
one of the LPI pumps circulate coolant through the reactor
core and out to a special heat exchanger to bring the
system temperature down to about 120#DE#-140#DE#F. Id.71
_________________________________________________________________

71. The LPI system is called the "decay heat removal system" when it
performs this function. NUREG/CR-1250 at 12.

                               64
Finally, there is an ECCS system called the "coreflood
tanks." These are two tanks almost completelyfilled with
water under a medium-pressure of about 600 psi. Id. They
stand above the reactor and a check valve prevents the
higher reactor core system pressure from driving more
water into them. Id. If a large pipe break occurs, it takes a
few minutes for the HPI and LPI pumps to deliver cooling
water to the core. Id. Therefore, the coreflood tanks are
designed to drop their thousands of gallons of water to cool
the core until the HPI and LPI pumps deliver cooling water.
Id.

C. Barriers to Release of Radioactive Materials into
the Environment.

A nuclear reactor must obviously have barriers designed
to prevent the fission products from entering the working
areas of the reactor or escaping into the environment.
NUREG/CR-1250 at 342. The first such barrier is the
ceramic fuel matrix in which the fission products are
produced. Id. The uranium dioxide (UO2) used in the TMI-2
reactor is a ceramic fuel which has microscopic boundaries
("grain boundaries") between the molecules. Daniel, Noble
Gas Transport at 87. These boundaries serve as
microscopic roadways for certain fission products to travel
out of the fuel. Id. Thus, some of the elements that are
volatile or gaseous at the operating temperature of the fuel
are able to migrate through the ceramic fuel. NUREG/CR-
1250 at 342. However, the majority of the fission products
that are produced are either trapped or chemically bound.
Id.

The second barrier to the release of fission products is
the fuel cladding. The UO2 ceramic pellets are sealed in the
fuel rods to prevent the fuel pellets from directly contacting
the water in the reactor core. There is a small gap between
the fuel and the fuel cladding. Noble gases such as krypton
and xenon, and other volatile nuclides are contained in that
gas. However, if a defect or rupture develops in the fuel
cladding, volatile fission products can be released into the
coolant. Id. at 343. At the time of the TMI-2 accident, the
Nuclear Regulatory Commission generally allowed operation

                               65
of a reactor with up to 1% of the fuel having a defect in its
cladding.72 Id.

The third barrier is the reactor coolant. Many of the
volatile fission products, the radioiodines and
radiohalogens, are soluble in the coolant in "ionic"
(electrically charged) form. Id. at 343. These materials can
be removed by demineralizers, such as those in the makeup
and purification system of the reactor, or they may remain
dissolved in the coolant. Id. The majority of these
radionuclides are contained in the primary coolant system,
Id., and are soluble in the coolant. Id. Their solubility
decreases and they tend to precipitate or "plate out" as the
pH of the primary coolant is increased. Id. The noble gas
radionuclides, kryptons and xenons, have very low
solubility in the coolant, particularly in the presence of
other gases such as hydrogen, and they evolve into a gas or
vapor phase above the coolant or wherever the coolant is
depressurized. Id.

The fourth barrier is the reactor pressure vessel and the
piping of the primary coolant system, which are made of
heavy walled steel. Id. The fifth barrier is the containment
building itself. It is designed to withstand
overpressurization and external impacts and contain or
delay fission product releases during an accident. Id.

V. THE ACCIDENT AND ITS AFTERMATH

A. The Accident at TMI-2.73
_________________________________________________________________

72. Even in the absence of defective fuel elements, a small background
concentration of fission products exists in the primary coolant system,
because of the fissioning of trace quantities of uranium ("tramp
uranium") in or on the fuel cladding material. NUREG/CR-1250 at 342.

73. Although the defendants have previously conceded that radioactivity
was released into the environment as a result of the TMI-2 accident, see
67 F.3d at 1119, there is apparently some dispute about the "specific
operation of the TMI-2 PWR during the accident. . . ." 927 F. SUPP. at
846. Our description of the accident is taken from defense exhibits.
Plaintiffs have not offered an explanation of how the accident occurred,
and have focused instead on the biological damage they allege it caused.

                               66
What has been described as the "[n]ation's worst nuclear
accident"74 began at about 4:00 a.m. on Wednesday, March
28, 1979, The Comptroller General Report to the Congress,
Three Mile Island: The Most Studied Nuclear Accident in
History 1 (1980). Ironically, the "nation's worst nuclear
accident" grew out of a minor malfunction, or transient that
occurred in the nonnuclear part of the system. NUREG/CR-
1250 at 3. For some reason, several feedwater pumps, 75
that normally drew heat from the PWR's cooling water,
shut-off automatically.76 Id. at 310. The system was
designed so that when the feedwater pumps tripped, the
main turbine and electrical generator also tripped. Id. Thus,
by design, the turbine and generator tripped approximately
one second later. Id. Three seconds after the turbine
tripped, the pressure in the reactor coolant system
increased to a level that caused the PORV to open in order
_________________________________________________________________

Nevertheless, a basic understanding of the defendant's theory of how the
accident occurred provides helpful background to a Daubert analysis of
the disputed expert testimony plaintiffs attempted to offer. It is in this
context only that we set forth a description of the accident. We caution,
however, that the description we set forth is intended only for the
limited
purpose of framing our Daubert discussion. It is not intended to suggest
the appropriate resolution of any factual dispute that may linger as to
the precise manner in which the numerous controls all failed at TMI.

74. Prior to the TMI-2 accident, there were "major" reactor accidents at
the National Reactor Testing Laboratory in Idaho in 1955 and 1961, at
the Fermi Reactor in Detroit, Michigan in 1966 and at Browns Ferry 1
in Alabama in 1975. BODANSKY, at 212-13. Major accidents outside of the
United States occurred at Chalk River, Canada in 1952, Windscale,
England in 1957, Lucens, Switzerland in 1969 and, perhaps the most
famous of all reactor accidents, at Chernobyl, in Ukraine about 30 miles
south of the border with Belarus, (both of which were then part of the
former USSR) in 1986. Id.

75. Neither the condensate nor the feedwater systems are unique to
nuclear power plants. Both systems are similar to those used in fossil-
fuel plants. NUREG/CR-1250 at 310.

76. The exact reason why the water pumps tripped has not been
determined. NUREG/CR-1250 at 311. However, it has been postulated
that the operations of a condensate polisher in the auxiliary building was
implicated in the tripping of a condensate pump which in turn caused
the tripping of the main feedwater pumps. NUREG/CR-1250 at 310-311.

                               67
to release the pressure. Id. When the PORV opened, the
fission process in the reactor core automatically shut down.
Id. Consequently, the heat generation in the reactor core
dropped to decay heat levels. J. A. Daniel, Noble Gas
Transport at 5.

However, the PORV did not close as it should have when
the system pressure was reduced to acceptable levels.
Instead, it remained open for approximately 2 hours.
Comptroller General Report ("CGR") at 2. Unfortunately, the
personnel operating Unit 2 did not realize that the PORV
had not closed. They believed that it had automatically
closed when the system was depressurized. Id. ;
NUREG/CR-1250 at 324. Because the PORV remained
open, reactor coolant water flowed from the reactor coolant
system into the reactor coolant drain tank, which is
designed to collect reactor coolant that is released from the
reactor coolant system through the PORV during power
operation. Daniel, Noble Gas Transport at 6. The continued
flow of reactor coolant water into the reactor coolant drain
tank caused a safety valve to lift on the drain tank and a
drain tank rupture disk to burst. Id. This rupture disk
burst allowed the reactor coolant water to be discharged
directly into the reactor building, which overfilled along
with its sump pumps. Id. The reactor building sump pumps
were on automatic and aligned with the auxiliary building
sump tank. Id. at 31. When the reactor building sump
pumps overfilled, some coolant water was transferred to the
aligned auxiliary building sump tank. Id. For some reason,
there was no rupture disk on the sump tank and reactor
coolant water was discharged directly into the auxiliary
building. Id. at 31; CGR at 2. The contaminated coolant
water continued to flow from the reactor building into the
auxiliary building for several days. CGR at 2. Estimates of
the amount of radioactive water discharged into the reactor
and auxiliary buildings range from 700,000 gallons,
Nuclear Energy Institute, The TMI 2 Accident: Its Impact, Its
Lessons, http://www.nei.org/pressrm/facts/TMI-2.htm>,
to 5,000,000 gallons. NUREG/CR-1250 at 339.

Approximately 2 minutes into the accident, the
emergency core cooling system ("ECCS") began pumping
water into the reactor core. CGR at 2. However, operations

                                68
personnel, still believing that the PORV had closed, and
therefore unaware that reactor coolant water was escaping
from the reactor coolant system, turned off most of the
water flowing to the core through the ECCS. Id. They did so
believing that they were preventing the reactor system from
becoming filled with water -- a condition they were required
to prevent. Id.

However, there was not enough coolant water being
circulated through the reactor coolant system to cool the
reactor core because reactor coolant water was being
discharged into the reactor building. Consequently, the core
reaction was producing more heat than the coolant system
was removing, and the core began to heat up. Daniel, Noble
Gas Transport at 6. The loss of reactor coolant water
allowed the reactor core to become uncovered. Id. Within
three hours of the beginning of the accident, as much as
two-thirds of the twelve-foot high core was uncovered.
Temperatures reached as high as 3500 to 4000 degrees
Fahrenheit or more in parts of the core during its
maximum exposure. THE REPORT OF THE PRESIDENT'S COMMISSION
ON THE ACCIDENT AT THREE MILE ISLAND, THE NEED FOR CHANGE:
THE LEGACY OF TMI 100 (1979) (THE KEMMENY REPORT).

About 2-1/2 hours into the accident, some of the fuel
rods in the reactor cracked, releasing xenon and other
fission product gases, which had accumulated in the fuel
rod gap between the fuel and the cladding, into the coolant
water. Daniel Aff. at P 28. Over the next few hours, more
fuel rods cracked, releasing radioactive iodine and cesium
into the primary coolant water as well as additional noble
gases. Id.

A series of events then unfolded involving various
reactions, valves and controls. The end result was that,
nearly 10 hours into the accident, there was a sudden
spike of pressure and temperature in the reactor building.
Id. at 329. Initially, the spike was dismissed as some type
of instrument malfunction. Id. at 330. However, operations
personnel learned on March 29th that the spike was
caused by the explosion of hydrogen gas in the reactor
building. Id. at 329; CGR at 2. Fears of another hydrogen
explosion developed when a hydrogen gas bubble was later
found in the reactor system. CGR at 2; NUREG/CR-1250 at

                               69
336, 338. Presumably, there was a concern that another
hydrogen explosion would damage the reactor vessel,
leading to further releases of radioactive material.
NUREG/CR-1250 at 338. However, the fears about another
hydrogen explosion were later learned to be unfounded. Id.;
CGR at 2.

During the last days of March and the first week of April,
operations personnel began to regain control and contain
the radioactive releases caused by the accident. See
NUREG/CR-1250 at 334-39. However, it was not until the
afternoon of April 27, 1979 that stable conditions were
finally established in TMI-2. Id. at 339.

B. Radioactive Materials Released to the
Environment.

The parties generally agree that the radioactivefission
products released to the environment as a result of the
accident escaped from the damaged fuel and were
transported in the coolant through the letdown line into the
auxiliary building. NUREG/CR-1250 at 343; Daniel, Noble
Gas Transport at 33 ("The major pathway forfission
product transport to the auxiliary building was through the
letdown piping of the makeup and purification system.");
Daniel Aff. at P 22. Once in the auxiliary building, the
radioactive fission products were released into the
environment through the building's ventilation system.77
NUREG/CR-1250 at 343; Daniel, Noble Gas Transport at
60. Because of the volatility of noble gases and
_________________________________________________________________

77. TMI-2 also contained a treatment system, called the "liquid radwaste
treatment system", which was designed to collect, process, monitor and
recycle or dispose of radioactive liquid wastes prior to discharge to the
environment. After the system processed the liquid radwaste, it was
discharged into the Susquehanna River. However, because the primary
coolant water flowed into the auxiliary building during the accident, the
liquid radwaste treatment system was overwhelmed and radioactive
materials were released to the Susquehanna River. The Nuclear
Regulatory Commission's Special Inquiry Group concluded that the
quantity of radioactive materials contained in the liquid released into
the
Susquehanna River was not significant. NUREG/CR-1250, at 347-51.
None of the plaintiffs here claim harm as a result of the releases of
liquid
radwaste into the river.

                                70
radioiodines, those elements were the primary
radionuclides available for release from the auxiliary
building. NUREG/CR-1250 at 343. Two krypton isotopes,
87 and 85, were not released in significant quantities
because of the short half-life of 87Kr and because of the
small amount of 85Kr in the reactor core. Id. Nonetheless,
despite the various filters, radioiodines were released.78
After the first day, the quantities of 88Kr and 135Xe were
reduced by radioactive decay. Id. All of the 133I contained in
the coolant which was released to the auxiliary building
eventually decayed to 133Xe and 133mXe. Id. These
radionuclides were the predominate ones released from the
plant to the environment. Id. at 344; Daniel Aff. at P 35.

C. Pathways of Exposure to Radioactive Materials.

The various mechanisms of human exposure to
radioactive materials after such materials have been
released into the environment are called "pathways".
NATIONAL RESEARCH COUNCIL, RADIATION DOSE RECONSTRUCTION FOR
EPIDEMIOLOGIC USES 28 (1995) (hereinafter "RADIATION DOSE
RECONSTRUCTION"). The pathways are"qualitatively well-
known and their relative importance is understood."
CHERNOBYL, at 31. Generally, when radioactive materials
from nuclear power plants are released into the
atmosphere, they are released into a region called the
"planetary boundary layer." This is an area between the
surface of the ground and an elevation of 100 meters.
RADIATION DOSE RECONSTRUCTION, at 28. Once the radioactive
material is released, turbulence in the atmosphere mixes
the effluent particles and gases within the resulting
contaminated cloud or "plume" and the plume is
transported downwind. Id. The mixing of the radioactive
particles and the transport of the resulting plume are called
"dispersion". Id.

Obviously, the extent and direction of a dispersion
depends on many factors including wind direction, wind
speed and weather, as well as the heat content of the
plume, and the characteristics of a given terrain over which
_________________________________________________________________

78. They included, 131I,133I and 135I,because of their abundance in the
coolant and the length of their half-life. Id.

                               71
the plume may be carried. CHERNOBYL, at 32. As the
radioactive cloud is dispersed and transported by prevailing
winds, exposure to the radionuclides first occurs through
external and internal irradiation. Id., at 31; RADIATION DOSE
RECONSTRUCTION, at 29. The contents of the plume are
depleted over time as the radionuclides settle to the ground
in response to gravitational forces ("dry deposition") of
through precipitation or combination with airborne
moisture such as fog (wet deposition). CHERNOBYL , at 31-32.
However, as suggested by some of our discussion above,
exposure can continue by external irradiation from deposits
of radioactive material, inhalation of any materials
suspended in the atmosphere, or transfer of the radioactive
material through the terrestrial and aquatic environment to
food and water, and then to internal irradiation. Id.

VI. LEGAL DISCUSSION

With the foregoing discussion in mind, we are ready to
begin our discussion of the District Court's evidentiary
rulings. The Daubert challenge to the plaintiffs' experts
implicates the reliability of the expert testimony that
plaintiffs sought to admit into evidence. We now begin our
analysis of that testimony, the issues of causation and the
scientific principles implicated by the plaintiffs' attempt to
establish the requisite nexus between the accident at TMI-2
and their injuries.

A. The Trial Plaintiffs' Appeal.

1. Background.

The 10 Trial Plaintiffs claim that their diseases, or the
fatal diseases of the decedents whose claim their personal
representatives assert, were caused by the radioactive
materials released into the environment as result of the
TMI-2 accident. More specifically, they allege their
conditions were caused by gamma (g) ray exposure from
radioactive iodine, xenon and krypton. In re TMI Litigation
Consolidated Proceedings, 927 F. Supp. 834, 840 (M.D. Pa.
1996)(the "Summary Judgment Opinion").

We have previously held that plaintiffs seeking to recover
for injuries allegedly caused by TMI-2 must show that: (1)

                                72
the defendants released radiation into the environment in
excess of the levels permitted by federal regulations in effect
in 1979, i.e., 0.5 rems (500 mrems) or 5 mSv; (2) the
plaintiffs were exposed to this radiation (although not
necessarily at levels prohibited by those regulations); (3) the
plaintiffs have injuries; and (4) radiation was the cause of
those injuries. See In re TMI, 67 F.3d 1103, 1119 (3d Cir.
1995), cert. denied, 516 U.S. 1154 (1996). We have also
held that the "exposure element requires that plaintiffs
demonstrate they have been exposed to a greater extent
than anyone else, i.e., that their exposure levels exceeded
the normal background level." Id. (citation and internal
quotations omitted).

Throughout this litigation, the defendants have conceded
that radioactive materials were released into the
environment, and that the releases at the plant boundaries
exceeded 0.5 rem (500 mrem). However, they claim that no
plaintiff was in an area where he or she could have been
exposed to dose in excess of 0.5 rem. In re TMI, 67 F.3d at
1109. Appellees point to a number of studies undertaken
by governmental entities in the years immediately following
the TMI-2 accident. The Nuclear Regulatory Commission
("NRC"), the Department of Energy ("DOE"), the
Environmental Protection Agency ("EPA"), the Department
of Health, Education and Welfare ("HEW"), a special
President's Commission (the "Kemmeny Commission"), a
special NRC investigation (the "Rogovin Report"), and the
Pennsylvania Department of Health, all studied various
aspects of the accident. Appellees' Br. at 3-4. The
government entities studied the timeline of events recorded
by in-plant computers and strip charts during the accident
to determine what was happening minute by minute. Id. at
4. The inquiry examined the records from monitors located
in several locations inside the plant including the
ventilation stack through which the radioactive releases
occurred. Offsite monitors at multiple locations where
either the utility operating the plant or the Commonwealth
of Pennsylvania had instruments collecting and recording
data on doses in the communities surrounding Three Mile
Island were also studied.79 Id. The governmental entities
_________________________________________________________________

79. Instruments used to measure airborne radiation, known as
thermoluminescent dosimeters ("TLDs"), were used by the utility,

                               73
also collected and assessed thousands of environmental
samples of milk, water, soil, vegetation, and food. Id. They
made whole body counters available at no charge to the
public, and over seven hundred people were scanned to see
if they had any radionuclides in their bodies from the
accident. Id. Local hospitals provided free thyroid scans to
anyone interested, and hundreds of people took advantage
of these scans to discover any radioactive iodine that might
have accumulated in their thyroids. Id. The DOE also
conducted an extensive examination of the damaged reactor
core in an attempt to quantify the amount of fission
products remaining so as to better calculate the quantity
that was released into the environment. Id.

Defendants insist that all of these studies consistently
concluded that the accident released something less than
nine million curies of the noble gases, xenon and krypton,
and radioactive iodine resulting in exposures of no more
that 100 mrem in the immediate vicinity of the plant, and
dropping quickly to tens or just a few millirems within a
few miles of the plant. Id. at 5. For example, the NRC
Special Inquiry Group Report concluded that the
radioactive releases resulted in an average equivalent dose
of 1.4 mrem to the approximately two million people living
in the area. NUREG/CR-1250 at 153. Defendants contend
that these studies conclusively demonstrate that the
accident did not cause in releases of radionuclides in
sufficient amount to pose a significant threat to the health
of the people living around Three Mile Island. Appellees' Br.
at 5. For example, the Ad Hoc Population Dose Assessment
_________________________________________________________________

Metropolitan Edison, and by the Commonwealth to monitor radiation in
the surrounding communities in a program known as the TMI Radiation
Environmental Monitoring Program ("REMP"). Summary Judgment
Opinion, 927 F. Supp. at 848. According to the NRC's Special Inquiry
Group, "TLDs provide the best estimate of the integrated radiation dose
at a specific location. . . ." NUREG/CR-1250, at 358. A TLD consists of
"[a] material, generally a salt such as lithium-fluoride, which can store
energy absorbed from nuclear radiation. This stored energy is later
released from the [material] by heating and evaluated electronically to
give information about the total radiation dose." President's Commission,
Report of the Task Group on Health Physics and Dosimetry 39 (1979).

                               74
Group80 concluded that the predominant exposure to people
outside the plant boundaries occurred in the north-
northwest sectors, the east-northeast sectors and the
south-southeast sectors, with the east-north east sector
registering the highest cumulative dose of 83 mrem. AD HOC
POPULATION DOSE ASSESSMENT GROUP, POPULATION DOSE AND
HEALTH IMPACT OF THE ACCIDENT AT THE THREE MILE ISLAND
NUCLEAR STATION 44 (1979). The Ad Hoc Group also
concluded the following regarding the potential health
effects on the population living around Three Mile Island:

       The projected total number of fatal cancers is less than
       1 (0.7). The additional number of non-fatal cancers in
       also less than 1 (0.7). The additional number of genetic
       effects for all generations is also less than 1 (0.7). . . .
       All of these values are small compared to either the
       existing annual incidence of similar effects or the
       potential effects estimated to result from the natural
       background radiation. . . . Comparing the total
       potential health impact of the accident with the
       estimated lifetime natural risk indicates that these
       effects, if they were to occur, would not be discernible.
       The uncertainties in the risk from low-level ionizing
       radiation would not alter this conclusion.

Id. at 60.

As the years passed and health concerns about the
accident persisted, the Commonwealth of Pennsylvania's
Department of Health conducted several epidemiological81
studies of the community surrounding Three Mile Island.82
_________________________________________________________________

80. The Ad   Hoc Group was composed of representatives of the Nuclear
Regulatory   Commission, the Environmental Protection Agency, and the
Department   of Health, Education and Welfare (now the Department of
Health and   Human Services).

81. Epidemiology is the "study of the distribution and determinants of
health-related states and events in populations and the application of
this study to control of health problems." FEDERAL JUDICIAL CENTER,
REFERENCE MANUAL ON SCIENTIFIC EVIDENCE 174 (1994)."Epidemiology is
concerned with the incidence of disease in populations and does not
address the question of the cause of an individual's disease." Id. at 167.

82. The studies are: Bratz, J.R., et al., Three Mile Island (TMI)
Pregnancy
Outcome Study-Final Report (1988); Tokuhata, George K., et al., Cancer

                                 75
The Department of Health examined pregnancy outcomes,
cancer incidence and cancer mortality in the Three Mile
Island area and compared them with state and national
norms. The Department's studies concluded there were no
significant differences between the studied groups and the
state and national norms. Appellees' Br. at 5. The
defendants believe that these epidemiological studies
further support their claim that the radionuclides released
by the accident did not pose any significant health risks.

However, the Trial Plaintiffs rely, in part, on a report of
the TMI Public Health Fund,83 which opined, inter alia, that
the aforementioned studies were seriously flawed insofar as
they attempted to calculate dose exposures to the
individuals in the communities surrounding Three Mile
Island. See THREE MILE ISLAND PUBLIC HEALTH FUND, A REVIEW
OF DOSE ASSESSMENTS AT THREE MILE ISLAND AND RECOMMENDATIONS
FOR FUTURE RESEARCH, APPENDIX A 1 (1984). Plaintiffs gathered
their own experts to conduct many of the tests
recommended by the TMI Public Health Fund in its report.
Appellants' Br. at 11. The scientific team that the Trial
Plaintiffs assembled focused on "biological indicators of
radiation dose." Trial Plaintiffs contend that those biological
indicators constitute a "body of evidence . . . greatly
overlooked or ignored in early studies. . . ." Id. at 12.
According to the Trial Plaintiffs, the biological indicators of
_________________________________________________________________

Mortality and Morbidity Incidence Around TMI, Division of
Epidemiological Research, PA Department of Health, (1985); Digon, E., et
al., Infant, Fetal Neonatal and Perinatal Mortalities in the Three Mile
Island Area, (1988); Ramasway, K., et al., Three Mile Island (TMI)
Population Registry-Based Cohort Mortality: 1979-1985 Period, (1988).

83. The Three Mile Island Public Health Fund was established as part of
the settlement of a class action for economic losses attributable to the
TMI-2 accident. The plaintiffs there consisted of three separate classes -
-
one class consisted of businesses which suffered economic loss, one
class consisted of individuals who suffered economic loss and one class
consisted of individuals who sought medical detection services allegedly
needed because of the accident. Under the settlement, a $25 million
fund was established, with $20 million available to pay the claims of the
businesses and individuals in the first two classes and $5 million set
aside for the Public Health Fund, the purpose of which was to, inter alia,
"finance studies of the long term health effects of the TMI incident." In
re Three Mile Island Litigation, 557 F. Supp. 96, 97 (M.D. Pa. 1982).

                               76
radiation dose conclusively demonstrate that area residents
were exposed to an equivalent dose of over 100 rem or 1 Sv.
Summary Judgment Opinion, 927 F. Supp. at 848. Perhaps
because of their faith in the reliability of these biological
indicators, Trial Plaintiffs proceeded to try their respective
claims on the theory that each of the Trial Plaintiffs had
been exposed to an equivalent dose of at least 10 rem or
100 mSv each.84 See Brief of Non-Trial Plaintiffs (No. 96-
7624), at 18, 38.

To support their contention that they were each exposed
to significantly higher doses of ionizing radiation than the
governmental studies calculated, and the defendants admit
to, the Trial Plaintiffs developed a "blowout" theory. Under
that theory, one or more unfiltered hydrogen blowouts
occurred on the afternoon of the first day of the accident,
whereby large quantities of radioactive noble gases and
other radioactive nuclides, such as iodine and cesium, were
expelled into the environment. Summary Judgment
Opinion, 927 F. Supp. at 857. They assert that, after the
blowout, an extremely dense, yet narrow, plume of
radioactive effluents traveled through the atmosphere
evading all of the radiation monitors in place in the areas
surrounding the plant and the communities. Id.

The "blowout" theory was first developed by Trial
Plaintiffs' expert, Richard Webb, who opined in a report
that a total of 106 million curies of noble gases were
released during the accident, more than half of which
escaped during a two and one-half hour "blowout" on the
afternoon of the first day of the accident. Webb did not
testify at the in limine Daubert hearing. After the first round
of hearings ended, Webb left a voice-mail message for
defendants' counsel recanting his proposed testimony. The
_________________________________________________________________

84. In contrast, the appellees' expert calculated that only one of the
Trial
Plaintiffs was exposed to a dose greater than 25 mrem. She is Jolene
Peterson, who appellants claim was exposed to an maximum dose of 75
mrem. Appellees' expert further calculated that plaintiffs Pearl
Hickernell, Ethelda Hilt, Leo Beam and Ronald Ward, were exposed to
maximum doses under 10 mrem and that plaintiffs Garry Villella, Lori
Dolan, Joseph Gaughan and Paula Obercash were exposed to maximum
doses between 15 and 25 mrem. Summary Judgment Opinion, 927 F.
Supp. at 852.

                               77
District Court concluded that Webb's recantation only
confirmed its intention to exclude Webb's proffered
testimony as unreliable.85 In re TMI Litigation Cases
Consolidated II, 911 F. SUPP. 775, 791 (M.D. Pa. 1996).

However, because of the significance of the "blowout"
theory to plaintiffs' case, the District Court did permit the
Trial Plaintiffs to use another witness -- a nuclear engineer
named David Lochbaum -- to replace Webb's testimony
about a blowout. Lochbaum testified at an in limine hearing
that significantly more than 10 million curies of noble gases
reached the environment as a result of the accident. He
opined that these gases were released from steam generator
B in the early hours of the accident. However, somewhat
contradictorily, he also testified that he "did not believe that
there was evidence of a blowout." In re TMI Litigation Cases
Consolidated II, 922 F. Supp. 997, 1052 (M.D. Pa. 1996).
He testified, however, that if a blowout did occur, it was of
limited length -- on the order of minutes and not over the
two or three hours Webb believed. Id. Nonetheless, he
testified that the blowout did release significant amounts of
noble gases even though it lasted only a short time. Id.

The District Court concluded that Lochbaum's testimony
was dependent upon other of the Trial Plaintiffs' experts
being able to demonstrate that significant amounts of
radionuclides were emitted. The court reasoned that if other
experts were able to competently testify about significant
amounts of noble gases being emitted, then Lochbaum's
testimony was admissible on the issue of the source of the
emissions. Thus, the court concluded that if no other
expert could competently testify about significant releases
of radionuclides, Lochbaum's proffered testimony about a
blowout must be excluded. Id. Consequently, the trial
plaintiffs proffered several witnesses whose testimony was
relevant to the existence of a blowout. It is those witnesses
for the most part, whose testimony was challenged under
Daubert, and whose reliability is now at issue.

With this background established, the stage is properly
set to begin our analysis of the District Court's Daubert
_________________________________________________________________

85. The Trial Plaintiffs do not argue that Webb's report and testimony
should have been admitted.

                               78
decisions regarding the Trial Plaintiffs' dose exposure
experts.

2. Standards Governing the Admissibility of Scientific
Evidence.

Federal Rule of Evidence 702 provides that:

       If scientific, technical, or other specialized knowledge
       will assist the trier of fact to understand the evidence
       or to determine a fact in issue, a witness qualified as
       an expert by knowledge skill, experience, training, or
       education, may testify thereto in the form of an opinion
       or otherwise.

In Daubert v. Merrell   Dow Pharmaceuticals, Inc ., 509 U.S.
579 (1993), the Court   set forth parameters for determining
when proffered expert   testimony can be admitted into
evidence.86 The Court   held

       an inference or assertion must be derived by the
       scientific method. Proposed testimony must be
       supported by appropriate validation -- i.e., "good
       grounds," based on what is known. In short, the
       requirement that an expert's testimony pertaining to
       "scientific knowledge" establishes a standard of
       evidentiary reliability.

Id. at 590.87 Rule 702 also requires that the evidence or
testimony "assist the trier of fact to understand the
_________________________________________________________________

86. In Daubert, the Court also held that Fed. R. Evid. 702 does not
incorporate the common law rule, known as the " Frye rule". See Frye v.
United States, 54 App. D.C. 46, 293 F. 1013, 1014 (1923). In Frye, the
court held that expert testimony is admissible only insofar as it is based
on a technique that is "generally accepted" in the scientific community.

87. Daubert concerned the admissibility of scientific evidence proffered
by
plaintiffs that demonstrated that the prescription anti-nausea drug,
Bendectin, marketed by defendant and ingested by pregnant women,
caused birth defects. Because the issue in Daubert was scientific
knowledge, the Court did not discuss "technical or other specialized
knowledge" to which Rule 702 also applies. Daubert, 509 U.S. at 590
n.8. Recently, however, the Supreme Court has decided that Daubert
applies not just to testimony based on "scientific" knowledge, but also to
"technical or other specialized knowledge." Kumho Tire Co., Ltd. v.
Carmichael, ___ U.S. ___, 119 S. Ct. 1167 (1999).

                                 79
evidence or to determine a fact in issue." "This condition
goes primarily to relevance." Id. at 591. This "consideration
has been aptly described . . . as one of `fit' ". Id. Rule 702's
" `helpfulness' standard requires a valid scientific
connection to the pertinent inquiry as a precondition to
admissibility. Id. at 591-92.

The Court in Daubert concluded that Rule 702"clearly
contemplates some degree of regulation of the subjects
about which an expert may testify." Id. at 589. Thus, the
Court established a "gatekeeping role for the judge." Id. at
597. The Court wrote:

       Faced with a proffer of expert scientific testimony, . . .
       the trial judge must determine at the outset, pursuant
       to Rule 104(a),88 whether the expert is proposing to
       testify to (1) scientific knowledge that (2) will assist the
       trier of fact to understand or determine a fact in issue.
       This entails a preliminary assessment of whether the
       reasoning or methodology underlying the testimony is
       scientifically valid and of whether that reasoning or
       methodology properly can be applied to the facts in
       issue.

Id. at 592-93. The Court held that these matters should be
established "by a preponderance of proof," Id. at 593 n.10,
and identified some "general observations," relevant to the
proponent's burden, while acknowledging that the factors it
identified were not all-inclusive. Id. ("[m]any factors will
bear on the inquiry.").

First, "a key question to be answered in determining
whether a theory or technique is scientific knowledge that
will assist the trier of fact will be whether it can be (and has
been) tested." Id. "Another pertinent consideration is
whether the theory or technique has been subjected to peer
review and publication." Id. Publication, which is an
element of peer review, "is not a sine qua non of
admissibility: it does not equate with reliability." Id.
_________________________________________________________________

88. Fed. R. Evid. 104(a) provides: "Preliminary questions concerning the
qualification of a person to be a witness, the existence of a privilege,
or
the admissibility of evidence shall be determined by the court, subject to
the provisions of subsection (b)[pertaining to conditional admissions].

                               80
However, submission to the scrutiny of the scientific
community is a component of "good science." Id.
Accordingly, "[t]he fact of publication (or lack thereof) in a
peer reviewed journal. . .will be a relevant, though not
dispositive, consideration in assessing the scientific validity
of a particular technique or methodology upon which an
opinion is premised." Id. at 594. Third,"in the case of a
particular scientific technique, the court ordinarily should
consider the known or potential rate of error, and the
existence and maintenance of standards controlling the
technique's operation." Id. Fourth, andfinally, "general
acceptance" can have bearing on the inquiry. Id.
"Widespread acceptance can be an important factor in
ruling particular evidence admissible, and a known
technique which has been able to attract only minimal
support with the community may properly be viewed with
skepticism." Id. However, "general acceptance" is "not a
necessary precondition to the admissibility of scientific
evidence." Id. at 597. Indeed, the Court specifically declined
to require general acceptance when it rejected the Frye rule.
See n.86 supra. Rather, general acceptance is but one
factor that is considered along with all other factors
relevant to the 702 inquiry.

The Court concluded by emphasizing that the "inquiry
envisioned by Rule 702 is . . . a flexible one," and by
reminding the trial courts that the "focus . . . must be
solely on principles and methodology, not on the
conclusions they generate." Id. at 595. The Court also noted
that the District Court should be mindful of other
applicable rules in assessing a proffer of expert scientific
testimony under Rule 702. Specifically, Rule 703 which
provides that expert opinions based on otherwise
inadmissible hearsay are to be admitted only if the facts or
data relied upon are of a type reasonably relied upon by
experts in the particular field in forming opinions; Rule 706
which allows the court in its discretion to procure the
assistance of an expert of its own choosing; and Rule 403
which permits the exclusion of relevant evidence if its
probative value is substantially outweighed by the danger of
unfair prejudice, confusion of the issues, or misleading the
jury. Id.

                               81
We applied the teachings of Daubert in deciding In re
Paoli Railroad Yard PCB Litigation, 35 F.3d 717 (3d Cir.
1994), cert. denied, 115 S. Ct. 1253 (1995)(hereinafter
"Paoli II"). There, we held that Rule 702 has two major
requirements. First of all, the proffered "expert" must be
qualified to express an expert opinion. This "qualifications"
requirement is liberally interpreted and includes"a broad
range of knowledge, skills, and training," Paoli II, at 741.89
However, "the level of expertise may affect the reliability of
the expert's opinion." Id.

Secondly, the proffered expert opinion must be reliable.
Thus, "an expert's testimony is admissible so long as the
process or technique [as opposed to the conclusion] the
expert used in formulating the opinion is reliable." Id. at
742 (emphasis added). We listed various factors enunciated
in Daubert that assist in evaluating whether a given
scientific methodology is reliable, and we also relied upon
several factors we had previously identified in United States
v. Downing, 753 F.2d 1224 (3d Cir. 1985). Paoli II, at 742.
We held that the District Court's inquiry under Rule 702
should be guided by the criteria set forth in Daubert and
Downing as well as other factors that may be relevant to a
given inquiry. The factors we specifically identified include:

       "(1) whether a method consists of a testable
       hypothesis; (2) whether the method has been subject to
       peer review; (3) the known or potential rate of error; (4)
       the existence and maintenance of standards controlling
       the technique's operation; (5) whether the method is
       generally accepted; (6) the relationship of the technique
       to methods which have been established to be reliable;
       (7) the qualifications of the expert witness testifying
       based on the methodology; and (8) the non-judicial
       uses to which the method has been put."

Paoli II, at 742 n. 8. We also noted that the proffered expert
testimony must assist the trier of fact. In other words,
admissibility depends in part on "the proffered connection
between the scientific research or test result to be
_________________________________________________________________

89. The liberal policy of admissibility under Rule 702 extends to the
substantive as well as the formal qualification of experts.

                               82
presented and particular disputed factual issues in the
case." Id. at 743.

Furthermore, we cautioned that the standard for
determining reliability "is not that high," Id. at 745, even
given the evidentiary gauntlet facing the proponent of
expert testimony under Rule 702. Thus, plaintiffs do not
"have to prove their case twice -- they do not have to
demonstrate to the judge by a preponderance of the
evidence that the assessments of their experts are correct,
they only have to demonstrate by a preponderance of
evidence that their opinions are reliable."90 Id. at 744. In
other words, "the evidentiary requirement of reliability is
lower than the merits standard of correctness." Id.

       "The grounds for the expert's opinion merely have to be
       good, they do not have to be perfect. The judge might
       think that there are good grounds for an expert's
       conclusion even if the judge thinks that there are
       better grounds for some alternative conclusion, and
       even if the judge thinks that a scientist's methodology
       has some flaws such that if they had been corrected,
       the scientist would have reached a different result."

Id. Thus, in Paoli II we explained

       the primary limitation on the judge's admissibility
       determinations is that the judge should not exclude
       evidence simply because he or she thinks that there is
       a flaw in the expert's investigative process which
       renders the expert's conclusions incorrect. The judge
       should only exclude the evidence if the flaw is large
       enough that the expert lacks the `good grounds' for his
       or her conclusions.

Id. at 746.91

The test of admissibility is not whether a particular
scientific opinion has the best foundation, or even whether
_________________________________________________________________

90. The distinction is indeed significant as it preserves the fact finding
role of the jury.

91. Such a flaw undermines the fact finding role of the jury by allowing
it to reach factual conclusions which may be based on "unreliable"
evidence and, therefore, are more likely to be erroneous.

                               83
the opinion is supported by the best methodology or
unassailable research. Rather, the test is whether the
"particular opinion is based on valid reasoning and reliable
methodology." Kannankeril v. Terminix International Inc.,
128 F.3d 802, 806 (3d Cir. 1997) (emphasis added). The
admissibility inquiry thus focuses on principles and
methodology, not on the conclusions generated by the
principles and methodology. Id. (citing Paoli II at 744). The
goal is reliability, not certainty. Once admissibility has been
determined, then it is for the trier of fact to determine the
credibility of the expert witness. Id. (citing Paoli II at 743-
746). "The analysis of the conclusions themselves is for the
trier of fact when the expert is subjected to cross-
examination." Id. Therefore, if the methodology and
reasoning are sufficiently reliable to allow the fact finder to
consider the expert's opinion, it is that trier of fact that
must assess the expert's conclusions. The inquiry is a
factual one, not a legal one.

Nonetheless, "conclusions and methodology are not
entirely distinct from one another." General Electric Co. v.
Joiner, ___ U.S. ___, 117 S. Ct. 512, 519 (1997). The court
"must examine the expert's conclusions in order to
determine whether they could reliably flow from the facts
known to the expert and the methodology used." Heller v.
Shaw Industries, Inc., 167 F.3d 146, 153 (3d Cir. 1999). "A
court may conclude that there is simply too great a gap
between the data and the opinion proffered." Joiner, at 519.
However, such an opinion will be excluded not because it is
necessarily incorrect, but because it is not sufficiently
reliable and therefore too likely to lead the factfinder to an
erroneous conclusion.

Here, the District Court assessed the disputed expert
testimony under Rule 702 and held that it did not meet the
conditions precedent to admissibility under Daubert. We
subject the District Court's interpretation of Rule 702 to
plenary review. Paoli II at 749. However, we review the
District Court's decision to admit or exclude scientific
evidence for an abuse of discretion. Joiner, at 519.92 An
_________________________________________________________________

92. In Joiner, the Court rejected the view that a district court's
decision
on the admissibility of scientific evidence should be reviewed under a
heightened or stringent abuse of discretion standard. That view is the
one we adopted in Paoli II at 749-50.

                               84
abuse of discretion arises when the District Court's
decision "rests upon a clearly erroneous finding of fact, an
errant conclusion of law or an improper application of law
to fact." Hanover Potato Products, Inc. v. Shalala, 989 F.2d
123, 127 (3d Cir. 1993). An abuse of discretion can also
occur "when no reasonable person would adopt the district
court's view." Id. However, we do not interfere with the
District Court's exercise of discretion "unless there is a
definite and firm conviction that the court below committed
a clear error of judgment in the conclusion it reached upon
a weighing of the relevant factors." Id.

With the parameters of our inquiry in mind of our review
in mind, the teachings of Daubert and the aforementioned
scientific principles as our guideposts, we can now proceed
to apply yardstick of Daubert to the expert opinions at issue
here and determine if they were properly excluded under
the Rules of Evidence.

3. Trial Plaintiffs' Dose Exposure Expert Witnesses.

i. Ignaz Vergeiner.

a. Qualifications.

Ignaz Vergeiner is a meteorologist with undergraduate
degrees in mathematics and physics, and a Ph.D. in
meteorology; all of which were earned at the University of
Innsbruck in Austria. He is an Associate Professor in the
Department of Meteorology and Geophysics at the
University of Innsbruck and has taught graduate and
undergraduate courses at that University for twenty years.
App. Vol. V., at 3578. He was proffered as an expert in
boundary level meteorology in alpine regions.93 His
_________________________________________________________________

93. During his testimony, Vergeiner offered the following definition of
"boundary layer meteorology": "Meteorology would be the scientific
description of processes occurring in the layer of air between the earth's
surface, land or ocean, an up to 10 miles, 20 miles, 50 miles, depending
on your discipline; even further, if you wish. But mainly it's the lower
10
miles, 15 miles. And boundary layer meteorology would be the same, but
restricted to the layer of air adjacent to the surface, which may be a few
hundred meters up to a couple of miles. And boundary layer
meteorology, the characteristic is that you work near the earth's surface,
which means you have friction and you have the influence of heat input

                               85
testimony was offered to explain how the hypothesized
plume containing the highly radioactive release that is part
of "blow out," traveled and dispersed throughout the area
surrounding Three Mile Island.

b. Vergeiner's Opinion.

Vergeiner's proffered testimony covered three areas. First,
as an expert in boundary level meteorology, he sought to
testify about the weather conditions at Three Mile Island
and the surrounding areas during, and immediately
following, the accident. He was to testify about his plume
dispersion hypothesis based upon his studies of the
weather conditions. Secondly, he sought to estimate
radiation doses in certain areas surrounding Three Mile
Island. Finally, he sought to testify about his distrust and
skepticism of the original plant data from TMI-2 concerning
plume dispersion and radiation releases in an effort to
counter the defendants' evidence regarding exposure.

Essentially, Vergeiner opined that a weather inversion, in
combination with the alpine terrain that surrounds Three
Mile Island, prevented the radioactive plume from rising
high into the atmosphere, spreading out and dispersing in
the expected "Gaussian" manner.94 App. Vol. V., at 4005-
09. Instead, he believed that the radioactive plume
remained narrow, concentrated and intense and moved
_________________________________________________________________

at the earth's surface. Now, for example, this means that the winds
change with height in the boundary layer much more than they do in the
upper part of the atmosphere. Then you would have the daily range of
temperature, warming and cooling, which would be mainly restricted to
the boundary layer. And you would have one characteristic, you might
have turbulence. You don't always have turbulence, but the boundary
layer is a place where you typically may find turbulence." App. Vol. V.,
at 3999-4000. Vergeiner also testified that the land surrounding Three
Mile Island consisted of alpine or mountain terrain. For meteorological
purposes, a mountain is a structure that is elevated 50 meters or more
above the flat terrain. Id. at 4006-07, 4081-82.

94. Under the "Gaussian plume model", dispersion is three-dimensional,
i.e., dispersion will be downwind, cross-wind and vertical. See
Environmental Software and Services, AirWare: Urban Air Quality
Assessment and Management (visited January 4, 1999)
http://www.ess.co.at/AIRWARE/gauss.html>.

                               86
erratically in a north, northwest direction from Three Mile
Island. He believed that it frequently came in contact with
hilly terrain which caused it to reconcentrate, and that
after it reconcentrated, it touched down on the ground and
exposed the population to high levels of radiation. Id. at
3583-85; 3761-68; 4017-29. To illustrate his plume
dispersion theory, Vergeiner produced a water model and a
"plume movie". The latter is not a "movie" at all, but is
rather a series of sketches he drew by which he illustrated
the plume movement he hypothesized. Id. at 3769-775;
4076-78. The water model is a video of a large scale model
he built in which colored water was injected into a tank
filed with clear water that contained a model of alpine
terrain. Id. at 3756-60.

Vergeiner's qualifications as an expert in meteorology
were not in dispute. Nonetheless, the defendants moved to
exclude all of his proffered testimony under Rule 702. After
a hearing, the District Court subjected his proffered
testimony to an exhaustive and rigorous Daubert/Paoli II
analysis and excluded the majority of it, including the
plume movie and the water model. In re TMI Litigation
Cases Consolidated II, 911 F. Supp. 775, 791-799 (M.D. Pa.
1996). However, the court held that, as an expert in
meteorology, Vergeiner could testify about the weather
conditions during and immediately following the accident if
the Trial Plaintiffs could demonstrate how that testimony
would assist the jury in determining a pertinent fact. Id. at
799.

c. Discussion and Conclusions.

The Trial Plaintiffs argue that by excluding the
overwhelming majority of Vergeiner's proposed testimony,
the District Court "elevate[d] its opinion of science over that
of Dr. Vergeiner's, even though the court had no training in
the complex meteorological issues that he discussed. . . ."
Trial Plaintiffs' Br. at 24. We disagree. Preliminarily, we
note that a proponent of rejected expert testimony could
always level such a challenge against an unfavorable
Daubert ruling. However, an adverse ruling under Daubert
does not, in and of itself, suggest that a court substituted
its opinion for that of a trained scientist. Here, we conclude
that the trial court did not substitute its scientific opinion

                                 87
for Vergeiner's. Rather, the court correctly applied the
Daubert/Paoli II guidelines and properly found the bulk of
Vergeiner's testimony "unreliable and therefore inadmissible
under Rule 702." 911 F. Supp. at 799. Although wefind it
unnecessary to review the District Court's application of
each Daubert/Paoli II criteria, we believe a few examples
demonstrate that the District Court's decision to exclude
the bulk of Vergeiner's proposed testimony was not an
abuse of discretion.

First, in formulating his plume dispersion hypothesis,
Vergeiner discarded standard and generally accepted
computer models, especially the Gaussian plume model.95
App. Vol. V, at 4003-07. At the hearing, Vergeiner testified
that the Gaussian plume model was not an adequate model
to hypothesize plume dispersion given the weather
conditions on the day of the accident, and considering the
terrain surrounding Three Mile Island. Id. at 4007; 4051-
54. In rejecting the standard computer models, Vergeiner
wrote in one of his two reports:

       Clearly, available synoptic meteorological96 observations
_________________________________________________________________

95. The Gaussian plume model was the model used by appellants'
expert, Keith Woodward, to formulate his opinion as to the atmospheric
dispersion of the radioactive materials released as a result of the
accident. See Affidavit of Keith Woodard, at P 14. However, by referring
to the Gaussian plume model, we do not mean to suggest that it is the
model Vergeiner should have used. Rather, it is mentioned only as an
example of a generally accepted computer model.

96. At the hearing, Vergeiner offered the following definition of
"synoptic
meteorology."

        Synoptic meteorology is essentially the--comes out of the
       realization that when you plot weather observations taken at the
       same time, you know, which could be nighttime in Europe and late
       afternoon in this country, then you can draw maps. And you start
       to interpret them and you find out that, you willfind certain
       prominent features, like weather fronts, and they would move in a
       coordinated way, right? You would get the rainsfirst in, God knows
       where, in Chicago, and later on you would get them further east.
       And this is what's called synoptic meteorology.

        And to do that, of course, you don't want to look only at surface
       observations, but you do want to look at upper air observations,

                               88
       cannot determine the flow field and dispersion
       characteristics down to a scale of hundreds of meters
       or a few kilometers, as needed to estimate local
       transport and diffusion from TMI releases. . . .

       So why not straightway model the flow numerically
       using the power of modern computers? Let me remind
       the reader of the enormous complexity of such a task.
       Transport and dispersion models exist to the hundreds,
       many of them in the nuclear industry or in the
       scientific "grey zone" around it. . . .

       Quite a few of these models are global in scale, and
       some apparently have succeeded in simulating the
       path and contaminating action of the Chernobyl clouds
       reasonably well, after years of tuning and verification
       on the many observations available. . . .

       Documentation is a problem, as well as the need for
       special graphics and internal routines, or compatibility
       of various computer languages. Not all applications
       have been successes. . . .

       It was my judgement, therefore, not only that it did not
       seem feasible to obtain access and results within a
_________________________________________________________________

       because the air moves faster at upper levels. And in order to
       interpret your features, you do want both surface and upper air
       observations.

        And for upper air, there is a network of balloons soundings, these
       big balloons with an instrument package, and they are launched
       every 12 hours at stations like Pittsburgh, New York--Albany, New
       York, Washington, D.C., stations at about that distance. And from
       those radio soundings, you get temperature and winds and pressure
       at upper levels. They are the backbone of synoptic meteorology.

App., Vol. V, at 4033-34. As part of his synoptic meteorological analysis,
Vergeiner presumably analyzed "a wide range of meteorological data,
including national data regarding the movement of weather fronts
throughout the country, regional data from the eastern part of the
United States, and local data from the TMI area." App. Vol. V, at 3549.
The District Court found that synoptic analysis is a standard
meteorological technique that has been subjected to significant peer
review. 911 F. Supp. at 794-95.

                               89
       limited time span and financial frame, but that
       relatively simpler, well-tested, more robust and
       accessible models might be just as good, even
       preferable. This may appear to do injustice to the more
       than 50 man-years' expert work condensed in this
       enormous structure. There is no doubt that each of
       these models is capable of computing flow structures
       very suggestive of real nature, but I couldn't convince
       myself that the enormously increased expense would
       bear a sound relation to similarly improved results.

Ignaz Vergeiner, Treatise on the TMI-2 Accident of March
28, 1979, Particularly its Meteorological Aspects Including
Transport and Dispersion of the Radionuclides Released 49-
50 (July 1994)(unpublished)(hereinafter "Vergeiner I"); App.
Vol. V, at 3634-35.

Rather than using the standard computer models,
Vergeiner chose to use a "numerical model" which he
initially referred to by the acronym "AMBIMET," Vergeiner
I, at 51; App. Vol. V, at 3636, but which he later called, in
his second report, the "FITNAH model operated by
AMBIMET." Ignaz Vergeiner, Treatise on the Meteorological
Aspects of the TMI-2 Accident 49 (February 1995)
(unpublished) (hereinafter "Vergeiner II"); App. Vol. V, at
3752. In any event, he described the model he used,
whether AMBIMET or FITNAH, as "a regional one, not
designed to simulate local flows on the scale of hundreds of
meters" that "requires proper synoptic input." Vergeiner I,
at 51-52; App. Vol. V, at 3636-37.

However, Vergeiner never provided any testimony,
documentation or any other evidence that the numerical
models he did use are generally accepted within the
meteorological or the broader scientific community.
Although the "general acceptance" test of Frye v. United
States, 54 App. D. C. 46, 293 F. 1013 (1923), was displaced
by the Federal Rules of Evidence, Daubert, 509 U.S. at 589,
"general acceptance" in the scientific community can "yet
have a bearing on the inquiry," and be an "important factor
in ruling particular evidence admissible." Daubert, at 594.
"[A] known technique which has been able to attract only
minimal support within the community may properly be
viewed with skepticism." Id. (quoting United States v.

                               90
Downing, 753 F.2d 1224, 1239 (3d Cir. 1985)). Thus, while
general acceptance is not the focus of the inquiry, it is a
relevant factor which may be considered. Accordingly, a
court may well cast a jaundiced eye upon a technique
which is not supported by any evidence of general
acceptance absent other indicia of reliable methodology.
Here, it is impossible to know whether the disputed model's
methodology can or has been tested or whether the model
has been subjected to peer review or publication. Neither
can we determine its known or potential rate of error.
Consequently, we can hardly conclude that the plume
dispersion model Vergeiner hypothesized meets the Daubert
requirement of evidentiary reliability.

Second, Vergeiner's "plume movie" (which, as noted
earlier, is but rather a series of sketches97 he drew to
illustrate his hypothesized plume movements) is based on
pure speculation. In his second report, Vergeiner presented
his opinion as to behavior of the plume. He wrote:

       For conclusion, I present my own tentative TMI plume
       "movie" for the first few hours. . . Its chief purpose is
       visualization of possible plume shifts and exposures,
       and realization of the kind of information we would
       need to be reasonably sure about transport and
       dispersion of TMI-2 effluents. [The plume movie] is the
       beginning of an investigation, not the end.

App. Vol. V, at 3769 (emphasis added). The speculative
nature of the plume movie was made even more apparent
during Vergeiner's deposition when he described the plume
movie.

       I make it clear that the [plume movie] and following are
       not meant to be -- I think the way I write it is that they
       are the beginning of a discussion and not the end of a
       discussion. . . . And I realize it's absolutely clear, and
       I state it, that this, this is an assumption, I think it's
       not an unreasonable one, it has some foundation, but
       at this stage it is just a, well, it's more than a
       provocation, but this --
_________________________________________________________________

97. The plume movie is located in Vergeiner II and is referred to therein
as Figure 9.1. Vergeiner II, at 67-71; App. Vol. V, at 3769-74.

                               91
       Q: It's the articulation of a hypothesis yet to be
       explored?

       A: Of a hypothesis, and it is an illustration, cer tainly
       an illustration of winds turning rapidly, which they did,
       that one is for sure, and the consequences of a plume,
       I wanted to illustrate how distorted a plume can
       become. I wanted to illustrate the effects. I just don't
       have enough of a database to prove details of this. This
       is absolutely clear and conceded. Absolutely clear .

Id. at 3941.

Rule 702 not only requires that the scientific opinion
proffered by the expert be supported by "good grounds,"
Daubert, at 590, it also mandates that the challenged
testimony "assist the trier of fact to understand the
evidence or to determine a fact in issue." This requirement
is one of relevance and expert evidence which does not
relate to an issue in the case is not helpful. Id. at 591. The
expert's testimony must "fit," and admissibility depends, in
part, on a connection between the expert opinion offered
and the particular disputed factual issues in the case. Paoli
II, at 743. "Fit is not always obvious, and scientific validity
for one purpose is not necessarily validity for other
unrelated purposes." Id. Here, Vergeiner's report and
testimony make clear that his plume movie was merely an
assumption visualizing possible plume movements. Given
its speculative character, the plume movie was properly
excluded under Daubert.

We note that in order for expert testimony to be reliable,
and therefore admissible, it must be based on the methods
and procedures of science rather than subjective belief or
speculation. Kannankeril, 128 F.3d at 806 (citing Paoli II,
35 F.3d at 744). Consequently, Vergeiner's plume movie,
and, (as will be discussed), his water model, are also
lacking in scientific reliability and are inadmissible because
of their speculative character. Nevertheless, we believe that
the plume movie and the water model are more
appropriately inadmissible because they lack fit.

The water model does not "fit." The water model is a
video of a large scale model tank, the bottom of which is a
topographical map of alpine terrain. The tank isfilled with

                               92
water, a dye is injected into the water and a current is run
through the water to simulate air flow. Its intended purpose
is to demonstrate how a material will disperse in the
atmosphere in relation to terrain and air patterns. See 911
F. Supp. at 792 n.10. However, the water model is just as
speculative as the plume movie. In his deposition, Vergeiner
testified that the water model was a demonstration and a
"tool for visualization," but was not intended"to exactly
simulate flows at the time of the TMI accident." App. Vol. V,
at 3930-31. In fact, Vergeiner testified that"[t]here's no way
to [simulate the complete atmospheric structure] in a
simple shallow water model." Id., at 3930. Simply put, the
water model does not assist the finder of fact and is,
therefore, not admissible under Rule 702.

Most importantly, we note that Vergeiner's proffered
testimony about the amount of radioactive materials
delivered to the areas where the plume traveled was totally
unreliable. That testimony was intended to explain how the
hypothesized plume containing the high concentrations of
radionuclides (believed to be part of the "blowout")
dispersed throughout the Three Mile Island Area exposing
the population to high levels of radiation.

In the field of radiation dose reconstruction, 98 "the
amount of radionuclides released from a site over a specific
period" is called the "source term". RADIATION DOSE
RECONSTRUCTION, at 16. A proper dose reconstruction study
should determine the amount of radionuclides released over
a specified period as well as the rate of release as a
function of time. Id. Consequently, a complete description
of the source term "includes what was released and in what
form and where and when the release occurred." Id. The
National Research Council's Committee on an Assessment
of [Center for Disease Control and Prevention] Radiation
Studies, has noted that if dose reconstruction studies are
credible, they "must rely on solid science, state-of-the-art
_________________________________________________________________

98. "[D]ose reconstruction is defined as the process of estimating doses
to the public from past releases to the environment of radionuclides . . .
.
These doses form the basis for estimating health risks and for
determining whether epidemiologic studies are warranted." RADIATION
DOSE RECONSTRUCTION, at 7.

                               93
methods, and careful peer review." Id. at 14. The Committee
further noted that "[u]ltimately, a dose reconstruction study
will be judged by the scientific community on the basis of
the technical quality of the study and its contribution to
science." Id.

Vergeiner is a meteorologist and not an expert in
radiation dose reconstruction.99 He admitted that he
received the source term he used to calculate the radiation
exposure from Trial Plaintiffs' counsel. App. Vol. V, at 4103-
04. He also testified that the gross magnitude of his
releases were the same as those postulated by Webb (before
Webb recanted his proposed expert testimony)100 but he
admitted that his release times were different than Webb's.
Id. However, Vergeiner was not able to explain the
difference. Id.

Moreover, Vergeiner violated an elementary principle of
credible dose reconstruction in estimating dose exposure.
The National Research Council's Committee on an
Assessment of CDC Radiation Studies has stated,"[t]he
credibility of a comprehensive source term study depends
upon confirming that all pertinent documents have been
seen and evaluated. Complete records are essential in
identifying the source term." RADIATION DOSE RECONSTRUCTION,
at 18. However, there is nothing in the record before us
that indicates that Vergeiner attempted to verify the source
terms he took from Trial Plaintiffs' counsel. Consequently,
his dose estimates can not be ruled credible or reliable.
Accordingly, they cannot assist a fact finder.

The problem inherent in the source terms that counsel
supplied was apparent when Vergeiner's plume
concentration hypothesis was tested. In his first report,
Vergeiner compared his estimated dose measurement to
that recorded by the thermoluminescent dosimeters
("TLD's") in the TMI Radiation Environmental Monitoring
Program101 for the TMI-area community of Middletown,
_________________________________________________________________

99. The District Court specifically found that Vergeiner was not an expert
in dose reconstruction or dose estimation. 911 F. Supp. at 797-98. The
Trial Plaintiffs do not challenge that finding.

100. See p. 77, supra.

101. See p.76 n.79, supra.

                               94
Pennsylvania. Vergeiner accepts that the TLD measured
dose from March 28, 1979, the date of the accident, to April
28, 1979, was 9.1 mrems (.91 mSv). Vergeiner I, at 10; App.
Vol. V, at 3595. But, his estimated dose measurement for
Middletown was 200 mrems (2mSv) in only three hours on
March 28, 1979. Id. Aside from expressing his basic and
fundamental mistrust of TLD's, see, e.g., App. Vol. V, at
4106, Vergeiner was unable to explain the discrepancy
between the TLD measured dose at Middletown and his
estimate. His best explanation was rather cryptic and
enigmatic:

       So the reader has a chance to draw conclusions for
       himself, even if I may suggest a conclusion, but the
       reader can check this, these assumptions, and he has
       a chance to see for himself. He can choose which he
       believes. He can reduce Webb's estimate, he can do
       other things.

App. Vol. V, at 3968. However, Vergeiner's testimony must
assist the fact finder in understanding the evidence or
determining a disputed issue of fact. His cryptic
explanation for the difference in dose measurement does
neither.

We conclude, therefore, that the District Court did not
abuse its discretion in excluding Vergeiner's testimony
about issues other than the relevant weather conditions.

ii. Charles Armentrout and Victor Neuwirth.

a. Qualifications.

Charles Armentrout has an undergraduate degree in
physics from the University of Maine, a master's degree in
physics from Wesleyan University and a master's degree in
radiological physics from Columbia University College of
Physicians and Surgeons. He is an Associate Professor at
the University of Southern Maine. Victor Neuwirth has an
undergraduate degree in chemistry from the State
University of New York at Stony Brook and a master's
degree in Chemistry from the State University of New York
at New Paltz. He is a laboratory associate and Professor of
Chemistry at the University of Southern Maine. Armentrout
and Neuwirth authored a joint report for the Trial Plaintiffs

                               95
(Affidavit of C. E. Armentrout and Victor J. Neuwirth, App.
Vol. VIII, at 7339-65);102 however, the District Court
discussed their proffered testimony separately.

Armentrout's proffered testimony based on his own
observations and experiences covered two separate areas:
(1) a discussion of what he called "anomalously high"
radiation readings registered shortly after the TMI-2
accident; and (2) a discussion of radiation survey meter
readings allegedly recorded by a local resident during the
TMI-2 accident.103 Neuwirth's proffered testimony concerned
the results of his analyses of soil samples taken from Three
Mile Island and the surrounding area. He performed his
analysis at Armentrout's request. Then, based on
Neuwirth's analyses, Armentrout made radiation dose
exposure estimates.

b. Armentrout's Observations and Experiences.

In his written report, Armentrout wrote that on March
31, 1979, he and a former student assembled radiation
detection equipment on the roof of the science building at
the University of Southern Maine. The equipment consisted
of a gamma-beta Geiger-Muller detector, pre-amplifier and
_________________________________________________________________

102. Armentrout and Neuwirth prepared an original report and a
revision. The original report is dated February 20, 1995, and the revision
is dated May 11, 1995. The revision makes no substantive changes to
the original report, it merely corrected some mathematical errors. App.
Vol. VIII, at 7827.

103. Armentrout's proposed testimony also covered two other areas. He
was to testify about the results of analyses of soil samples taken from
Three Mile Island and surrounding areas that Neuwirth performed at his
request. He was also to give an explanation of the rate-dependent
behavior of Geiger-Muller radiation detectors. However, in an
unpublished order and opinion, the District Court precluded Armentrout
from testifying as to the substance of Neuwirth's soil sampling analyses.
In re TMI, No. 88-1452 (M.D. Pa. Nov. 9, 1995). The Trial Plaintiffs do
not
challenge that ruling. Armentrout's proposed testimony about Geiger-
Muller radiation detectors was not discussed by either party in the
District Court. 911 F. Supp. at 799 n.22, and the Trial Plaintiffs do not
discuss it in the brief they filed in this appeal. Consequently, we assume
that this portion of Armentrout's proposed testimony has been
abandoned by the Trial Plaintiffs. In any event, the issue is clearly
waived.

                               96
count divider. Affidavit of C. E. Armentrout and Victor
Neuwirth, at 2-3; App. Vol. VIII, at 7340-41. In his report
he wrote, and at the in limine hearing he testified, that the
detection equipment recorded two "anomalous bursts" of
radiation activity. Affidavit, at 3; App. Vol. VIII, at 7341; Tr.
at 1249; App. Vol. VIII, at 7769. He described the bursts as
"significant radioactive sample[s]. . . detectable and
identifiable only then as being mixed beta-gamma
radiation." Affidavit, at 3; App. Vol. VIII, at 7341. He
memorialized his observations in a letter to the President of
the University of Southern Maine. Exhibit A to Affidavit;
App. Vol. VIII, at 7367-72. In addition to his own
observation of anomalous bursts of radiation, Armentrout's
report claims that "one or more governmental installations
near Portland," Maine, recorded radiation readings similar
to those he recorded. Affidavit, at 4; App. Vol. VIII, at 7342.
Armentrout also notes that an article in the February 8,
1980 issue of SCIENCE magazine reported that elevated levels
of Xenon-133 (133Xe) were recorded in Albany, New York, on
March 29 and 30, 1979. In the opinion of the authors of
that article, the increased levels of 133 Xe "could be
attributed to releases from the Three Mile Island reactor
accident." App. Vol. VIII, at 7375. Armentrout believes that
the SCIENCE magazine article confirms his conclusion based
on his recorded bursts of radiation activity, that the TMI
plume passed over the area. Affidavit, at 4; App. Vol. VIII,
at 7342. However, Armentrout candidly admitted that his
observed readings did not tell him what radionuclides were
released as a result of the accident or how large the
releases were. Tr. at 1290; App. Vol. VIII, at 7810.

The defendants did not challenge Armentrout's
qualifications as an expert. Rather, they argued that this
portion of his proffered testimony would not be helpful to
the trier of fact. The court declined to "trudge through the
Daubert/Paoli II" analysis and simply found that this
portion of Armentrout's proffered testimony does not" `fit'
within any material fact in issue." 911 F. Supp. at 800.
Consequently, the court precluded Armentrout from
testifying about his observation of anomalous bursts of
radiation. Id.

Armentrout was also proffered to testify about efforts he
made to verify radiation readings taken by residents living

                               97
near Three Mile Island during the accident. In his report,
he wrote that in 1992 he had several telephone
conversations with a man who lived on the west shore of
the Susquehanna River opposite Three Mile Island in
Etters, Pennsylvania. According to Armentrout, that man
claimed that he was trained in the use of radiation
detection instruments and said that he had recorded and
preserved "significant gamma emissions from TMI made in
the time-frame of the accident." Affidavit, at 24; App. Vol.
VIII, at 7362. Armentrout located similar instruments and
traveled to the Three Mile Island area to visit the man and
verify the readings. However, Armentrout could notfind
him. Nonetheless, Armentrout met a neighbor of the man
who remembered that he (the neighbor) and the man
Armentrout was seeking had purchased identical detection
instruments. The neighbor told Armentrout that he took a
reading during the accident that sent his detection
instrument off scale. Armentrout opined that this
conversation verified the missing man's reports of high
readings taken during the accident.

Not unexpectedly, the defendants challenged this portion
of Armentrout's proffered testimony as being totally
unreliable, rank hearsay. The District Court agreed and
precluded this portion of Armentrout's proffered testimony.
911 F. Supp. at 800-801.

c. Discussion and Conclusion.

We conclude that the District Court properly precluded
both portions of Armentrout's proffered testimony. His
testimony about his attempts to verify the high radiation
readings made by the unidentified man in Etters is purely
anecdotal and any reliance on the unconfirmed Etters
readings is totally lacking in scientific reliability. Moreover,
his proffered testimony about the readings of bursts of
radiation activity fails to satisfy the helpfulness prong of
Rule 702. Armentrout's equipment on the roof of the
university's science building recorded two bursts of
radiation activity. Those two observations, his claim that
government installations around Portland, Maine, recorded
similar activity, and the article in SCIENCE magazine, form
the basis of his conclusion that the TMI plume passed over
the northeastern part of the United States.

                                98
Rule 702's "helpfulness" or "fit" prong"requires a valid
scientific connection to the pertinent inquiry as a
precondition to admissibility." Daubert, at 592. Armentrout
merely assumed that his observations of two bursts of
radiation activity were the result of the TMI plume passing
over his area of southern Maine. That assumption is
supported by nothing other than conjecture, and we do not
believe that the District Court erred in ruling the evidence
inadmissible under Rule 702.

Moreover, assuming arguendo that Armentrout's opinion
that the TMI plume passed over the northeast United States
has scientific reliability, his opinion still would not be
helpful to the trier of fact. The Trial Plaintiffs proffered
Armentrout's testimony in an effort to demonstrate that
they were exposed to levels of radiation sufficient to cause
their injuries. They based their trial strategy on the theory
that as a result of the accident, they were exposed to an
equivalent dose of at least 10 rems or 100 mSv each. 104
However, Armentrout admitted that he could not tell with
any degree of scientific certainty how large the radioactive
releases from the accident were. The connection between
his testimony and a crucial fact in issue, i.e., whether the
Trial Plaintiffs were exposed to equivalent doses of 10 rems
or 100 mSv each was tenuous at best because he could not
testify as to the magnitude of the releases of radionuclides.

d. Neuwirth's Soil Sample Analyses and Armentrout's
Dose Estimates.

As noted above, Neuwirth performed analyses of soil
samples obtained from the Three Mile Island area at
Armentrout's request. Neuwirth concentrated the soil
samples by chemical extraction and used a sodium iodine
detector to take integrated counts of radionuclides.
Affidavit, at 7-9; App. Vol. VIII, at 7345-7347. Although
Neuwirth found that certain Three Mile Island area soil
samples contained radioactive materials, he was unable to
identify specific radionuclides. Affidavit, at 21; App. Vol.
VIII, at 7359. Because he was unable to identify any
specific radionuclide, Armentrout directed him to calculate
the half-life of each sample as a whole. Neuwirth calculated
_________________________________________________________________

104. See p. 77, supra.

                               99
the gross activity of the samples in 1994 and then
recounted the gross activity of the same samples one year
later in 1995. Based on these two points, Neuwirth
calculated a generalized half-life calculation for each of the
samples. Affidavit, at 14-15; App. Vol. VIII, at 7352-53.
From the analyses of the soil samples and the calculation
of the gross activity of the samples, Neuwirth and
Armentrout concluded that the gross radioactivity in the
Three Mile Island soil samples was attributable tofission
products from the reactor accident. Affidavit, at 20; App.
Vol. VIII, at 7358 ("Thus, these decay data and at least
some of the test results lead us to infer that significant
quantities of nongaseous primarily beta-emittingfission
product nuclides were released in the TMI event.").

Armentrout then used the half-life calculations to make
dose estimates. He attributed the difference between the
two counts to the decay of fission products having a half-
life of about one-year,105 such as cesium-134 (134Ce) or
cerium-144 (144Cr). Affidavit, at 16, 23; App. Vol. VIII, at
7354, 7361; see also Affidavit, at 21; App. Vol. VIII, at 7359
Extrapolating back to 1979, the year of the accident,
Armentrout opined that there must have been thousands of
times the amount of fission products in the soil then.
Affidavit, at 16; App. Vol. VIII, at 7354. For example, the
gross activity of soil sample no. 19887 was measured to
have 1.2 picocuries per gram in 1995, Affidavit, at 15; App.
Vol. VIII, at 7353, which Armentrout extrapolated back to
a 1979 activity of 320,000 picocuries per gram. 106 Affidavit,
at 16; App. Vol. VIII, at 7354.
_________________________________________________________________

105. Armentrout attributed the difference in gross activity between the
two counts to radionuclides having a half-life of about one year because
radionuclides having extremely short half-lives would have disappeared
from the samples and no activity would be detected in the year interval
between 1994 and 1995, while radionuclides having long half-lives are
regarded as stable and no activity would be detectable in just one year.
App. Vol. VIII, at 7822. Further, Armentrout regarded radionuclides
having half-lives of about one year to be not naturally occurring and,
therefore, fission products. Id. at 7794.

106. A pico is one-trillionth (10-12) of a given unit. MEDICAL EFFECTS,
APPENDIX III, CONVERSION T ABLES.

                               100
Although Neuwirth's expert qualifications were accepted,
his proffered testimony was challenged as lacking"fit."
Defendants argued that no valid connection could be made
between the results of his soil samples and the TMI
accident. Armentrout's extrapolation back was also
challenged as lacking scientific reliability. After a
Daubert/Paoli II analysis, the District Court found that
neither opinion was derived from scientific method and
neither represented good science. Therefore, the court
precluded Neuwirth and Armentrout from testifying. 911 F.
Supp. at 804.

e. Discussion and Conclusion.

We find no error in the Court's ruling. Neuwirth and
Armentrout hypothesized that the radioactive decay that
Neuwirth's analyses found in the TMI soil samples was
directly attributable to fission products released to the
environment by the reactor accident. That hypothesis is
testable, and it was in fact tested. However, the results of
that testing undermined Neuwirth's conclusions.

Because Neuwirth was unable to discover any specific
radionuclides causing the activity he found in his analyses,
Armentrout sent portions of the samples to Data Chem
laboratory. That lab was to perform a spectrographic
analysis capable of identifying specific radionuclides and
activity levels for each identified radionuclide. App. Vol.
VIII, at 7812-13. Data Chem's analyses found that the
overwhelming portion of the activity in the samples was the
result of naturally occurring background radionuclides.
App. Vol. VIII, at 7887-89; see also App. Vol. VIII, at 7636
and App. Vol. XIV, at 11679-87. The only fission product
found by Data Chem was cesium-137 (137 Ce). Armentrout
testified in his deposition that 137 Ce was "ubiquitous"
because of fallout from nuclear weapons testing 107 and
because it is a fallout product from the Chernobyl accident.
App. Vol. VIII, at 7468. Consequently, Armentrout conceded
that it was impossible to determine the source of 137Ce. Id.

However, Armentrout did not modify his hypothesis as a
result of the Data Chem findings:
_________________________________________________________________

107. See p. 65, supra.

                                101
       Q: Did you factor into your revised report any of the
       information communicated to you in the Data Chem
       report?

       A: No, I never have.

App. Vol. VIII, at 7819. Daubert recognized that science is
"an empirical endeavor in which testing plays a crucial
role." REFERENCE MANUAL ON SCIENTIFIC EVIDENCE,at 71. Indeed,
a "key question to be answered in determining whether a
theory . . . is scientific knowledge that will assist the trier
of fact [is] whether it can (and has been) tested." Daubert,
at 593.

Here, the hypothesis was undermined by Data Chem's
testing, yet the hypothesis was not further modified or
explained in view of Data Chem's "analysis." Armentrout
and Neuwirth's failure to properly revise their attribution of
the gross radioactivity in the soil samples to fission
products from the reactor accident is the antithesis of good
science and dramatically undermines their proffered
opinions.

Moreover, the half-life back calculation methodology
Armentrout used to estimate the levels of fission products
released during the accident was based on an assumption
that the gross activity in the samples was due tofission
products. Armentrout's own testimony established theflaws
in that approach. Since he was unable to identify any
specific radionuclides in the soil samples, Neuwirth
calculated the gross activity in the samples at two points in
time and determined the decay rate in the samples. Then,
Armentrout made an assumption that the gross activity in
the samples was due to fission products released in the
accident and that the decay rate Neuwirth calculated
established the half-life of the fission product radionuclides.
He then extrapolated the levels found in 1994 back to 1979
and concluded that the samples had been contaminated
with high levels of fission product nuclides as a result of
the reactor accident. However, the flaw in Armentrout's
half-life calculation methodology lies in the fact that, as
Armentrout's report conceded, "all soil samples contain
some natural radioactive materials." Affidavit, at 16; App.
Vol. VIII, at 7354. Consequently, it is impossible to

                               102
determine the half-life of any particular radionuclide in a
sample which has an admittedly unknown mix of
radionuclides, because any observed decline in activity may
be due to a mix of radionuclides with short half-lives and
radionuclides with long half-lives. Armentrout admitted as
much in his deposition:

       Q: Are you actually counting the half-life of any
       particular radionuclide or are you actually counting the
       decrease in counts of the mixture?

       A: What we're doing is taking the two, a pair of v alues
       for any of the sources, any of the numbers, sample
       numbers.

       Q: And these are all integrated counts, aren't the y?

       A: Those are all integral counts, yes, and we're t aking
       the value of the later time and the earlier time and a
       known time in between and calculating from, for the
       exponential decay law what the effective half-life of that
       material is, based upon these data.

       Q: The effective half-life of the material is not referring
       to any particular radionuclide, but a mix of whatever is
       in there, correct?

       A: That's very true.

       Q: So it may be a large decay of something with a
       short half-life or a small decay of something with a very
       long-half life, correct?

       A: That's correct.

       Q: Is it appropriate, given that range, to arrive at any
       conclusion concerning the half-life of any particular
       radionuclide?

       A: Depending upon what's in the mix, it could or
       couldn't be.

       Q: And you don't know what's in the mix, correct?

       A: Well, if we examine each of the spectra we coul d
       see, for example, there is or is not any cesium which is
       30 years. Over a year's span of time the long half-life
       material like cesium would be level. In other words,

                               103
       wouldn't raise or lower the base. Anything else in there
       that I can think of, the natural stuff like the uranium
       decays would be all along. Anything that's short, weeks
       or months or whatever, would have been gone, so they
       would be zero. So if you don't have many items in
       there, then I think your data are all right, at least
       temporarily.

       Q: On a tentative basis?

       A: Tentative basis, yes, for a one-year span for t wo
       readings. Nobody is saying it's probative, but we want
       to keep watching these to see how the decay, because
       then you can plot the picture of the curve and begin to
       get its shape. . . .

App. Vol. VIII, at 7503 (emphasis added). Trial Plaintiffs
now complain because the District Court refused to admit
testimony of a witness who conceded that his opinion was
not probative of the very issue the Trial Plaintiffs sought to
establish through that testimony. Moreover, Armentrout
conceded that using only two points in time, one year
apart, to count the activity in the samples, does not tell
anything about the sample other than the average half-life
for the entire mix of radionuclides. He testified that:

       If you have a mixture of materials and you do this kind
       of work, you are going to get I suppose an average half-
       life for the mix. But I am not sure what it means.

App. Vol. VIII, at 7793.

Armentrout's assumption that the gross activity in the
soil samples was due to fission products was not supported
by his own methodology. He essentially admitted that the
methodology of counting gross activity in the samples at
only two points in time to establish a half-life of the
radionuclides in the sample would not enable him to
identify any specific radionuclide, let alone afission
product radionuclide, but would only produce an average
half-life for the entire mix of unknown radionuclides. His
assumption that the activity was due to fission products
remains just that, an assumption. Although Daubert/Paoli
analysis does not preclude testimony merely because it may
be based upon an assumption, the supporting assumption

                                  104
must be sufficiently grounded in sound methodology, and
reasoning to allow the conclusion it supports to clear the
reliability hurdle. Assumption-based conclusions that do
not meet that test can hardly be relied upon as"good
science." Here, Neuwirth made an intermediate count of
one of the soil samples and discovered that 75% of the
activity disappeared in one month. This, in turn, suggested
that the radionuclide in the sample was not a fission
product radionuclide but rather naturally occurring radon.
App. Vol. VIII, at 7495-96.

Consequently, because Armentrout's attribution of the
difference between the two counts to the decay offission
products was an assumption based on a flawed
methodology, Armentrout's use of data derived from that
assumption to extrapolate back to 1979 to arrive at the
conclusion that the soil samples were contaminated with
high levels of accident released radionuclides was
completely lacking in scientific validity and reliability.
Because the methodology used to produce the data upon
which Armentrout extrapolated back to arrive at dose
estimates lacked scientific validity and reliability, we need
not determine whether "extrapolation back in time, using
known levels of compounds and a scientifically valid
mathematical formula for the extrapolation, would meet the
standards of Rule 702 and Daubert." Heller v. Shaw, 167
F.3d at 162. The data which Armentrout developed from his
flawed methodology was unreliable and it can to be
morphed into "good science" by scientifically valid
mathematical back-extrapolation.

Accordingly, the District Court did not abuse its
discretion in excluding Neuwirth and Armentrout's soil
sample analyses, the half-life calculations and extrapolated
dose estimates.

iii. James Gunckel

a. Qualifications.

James Gunckel is a biologist who earned an
undergraduate degree from Miami University (Ohio) and a
master's degree and Ph.D. from Harvard University. He is a
Distinguished Professor emeritus at Rutgers University in
New Brunswick, New Jersey. Before his retirement he was,

                                105
at various times, Chairman of the Botany Department,
Chairman of the Radiation Science Center, Chairman of the
Department of Radiation and Environmental Health and
Safety, and Chairman and Organizer of the Health Safety
Council. In addition to his academic and administrative
appointments at Rutgers, Gunckel collaborated, over a
twenty year period, with the late Arnold A. Sparrow, Ph.D.,
at the Brookhaven National Laboratory, studying the effects
of radiation on plants. He is, as the District Court
acknowledged, "a pioneer in the area of studying radiation
effects on plants." 911 F. Supp. at 809. His report consisted
of an evaluation of trees in the Three Mile Island area
which he opined were damaged by radiation and an
investigation he made of TMI area residents who claimed to
have experienced radiation induced symptoms. His
involvement as an expert witness began in 1987, eight
years after the reactor accident. Based on his evaluation
and investigation, Gunckel opined as to the radiation dose
to which the trees and the residents were exposed.

                               106
Volume 3 of 4

Filed November 2, 1999

UNITED STATES COURT OF APPEALS
FOR THE THIRD CIRCUIT

Nos. 96-7623/7624/7625

IN RE: TMI LITIGATION

LORI DOLAN; JOSEPH GAUGHAN; RONALD
WARD; ESTATE OF PEARL HICKERNELL;
KENNETH PUTT; ESTATE OF ETHELDA HILT;
PAULA OBERCASH; JOLENE PETERSON; ESTATE OF
GARY VILLELLA; ESTATE OF LEO BEAM,

       Appellants No. 96-7623

IN RE: TMI LITIGATION

ALL PLAINTIFFS EXCEPT LORI DOLAN, JOSEPH
GAUGHAN, RONALD WARD, ESTATE OF PEARL
HICKERNELL, KENNETH PUTT, ESTATE OF ETHELDA
HILT, PAULA OBERCASH, JOLENE PETERSON, ESTATE
OF GARY VILLELLA AND ESTATE OF LEO BEAM,

       Appellants No. 96-7624

IN RE: TMI LITIGATION

ALL PLAINTIFFS; ARNOLD LEVIN; LAURENCE
BERMAN; LEE SWARTZ

       Appellants No. 96-7625

ON APPEAL FROM THE UNITED STATES DISTRICT
COURT FOR THE MIDDLE DISTRICT OF PENNSYLVANIA
(Civil No. 88-cv-01452)
(District Judge: Honorable Sylvia H. Rambo)
ARGUED: June 27, 1997

Before: GREENBERG and McKEE, Circuit Judges, and
GREENAWAY, District Judge*

(Opinion filed: November 2, 1999)

b. Gunckel's Opinion.

Gunckel believed that prior estimates of the amount of
radiation released as a result of the accident were
unreliable. Gunckel Affidavit of May 13, 1993, at 1-5
(hereinafter "1993 Affidavit"). Thus, he devised a method of
estimating dose exposure based on his work with Dr.
Sparrow at the Brookhaven National Laboratory where they
created a gamma field to irradiate plants in order to study
the effects of the radiation on the plants. The gamma field
was operated as follows:

       [t]here was a cobalt-60 source, for gamma radiation, in
       the center of the field. The plants, mostly seedlings and
       cuttings, were planted in concentric rows around the
       source and planted so that successive rows reflected a
       "doubling dose" concept, for one could expect that to
       double the dose could double the effect. The source
       was lowered below the ground to permit entry for two
       hours of watering, cultivation and data taking. The
       observations centered on slight and severe growth
       inhibition or a lethal dose to growth processes from
       both chronic and acute exposure.

1993 Affidavit, at 5-6; App. Vol. V, at 3320-21. Gunckel
testified at the in limine hearing that, except for the two
hours a day that the gamma source was lowered into the
ground, the plants were constantly irradiated through the
growing season, i.e., April through November, for a period
of 20 years. App. Vol. V, at 3485. The plants, randomly
designated, but consisting of hardwoods as well as conifers,
were exposed to a controlled amount of radiation, ranging
from an absorbed dose of 2,000 rads (20 Gy) for the plants
_________________________________________________________________

* The Honorable Joseph A. Greenaway, Jr., United States District Court
Judge for the District of New Jersey, sitting by designation.

                               108
closest to the gamma source to 2 rads (20 mGy) for the
plants farthest from the gamma source. Id. at 3484.

Gunckel explained that irradiation has direct and indirect
effects on plants. The two most import direct effects are
mitotic delay and cell death, both of which are due to
damage to the nucleus of the plant. 1993 Affidavit, at 7;
App. Vol. V, at 3322. The most significant indirect effect is
growth inhibition. 1993 Affidavit, at 6; App. Vol. V, at 3321.

From their observations of the effects of the irradiation on
the plants in the gamma field, Gunckel and Sparrow
determined the dose needed to cause a certain effect in a
plant. App. Vol. V, at 3484 ("That was our basic objective,
and the basic objective was simply to create a data bank of
correlating dose with effects on a variety of plants.").
Applying his work at Brookhaven to the TMI reactor
accident, Gunckel hypothesized that:

       Radiation induced growth effects in trees would occur
       in areas where residents experienced symptoms
       indicating exposures to radioactivity at the time of the
       TMI accident and that those tree effects would occur in
       several species showing relative sensitivities (slight and
       severe growth effects, and lethality) corresponding to
       those determined in Brookhaven.

Gunckel Affidavit of October 23, 1995, at 12 (hereinafter
"1995 Affidavit"); App. Vol. V, at 12. Using the Brookhaven
gamma field data, Gunckel found three species of trees
which are present in the Three Mile Island area for which
there was radiosensitive data from the Brookhaven
experiments. 1993 Affidavit, at 9; App. Vol. V, at 3324.
Those trees were spruce, pine and Norway maple. Id.

Pursuing his hypothesis, Gunckel interviewed 15
residents of the TMI area regarding the health effects they
experienced as a result of the reactor accident. 108 App. Vol.
V, at 3490-92. He interviewed the residents not to
_________________________________________________________________

108. Gunckel described the radiation induced health effects as "malaise,
metallic taste, cessation of menses, epilation, sore throat, petechiae,
diarrhea, conjunctivitis and rhinitis, which indicate the radiation
sickness syndrome of 100-300 rems [1-3 Sv]. 1993 Affidavit, at 11; App.
Vol. V, at 3326.

                               109
determine whether "what they complained of was true or
false." Id. at 3490. Rather, he was "trying to associate
people with possible episodic evidence [of radiation induced
symptoms] with a plant indicator." Id. Based on his
interviews, Gunckel concluded that 5 of the 15 people were
exposed to erythemic doses, i.e., an equivalent dose
sufficient to cause erythema.109 Id. at 3492. He testified that
an erythemic dose is between 300 rems (3 Sv) and 360
rems (3.6 Sv). Id. at 3496. Consequently, he concluded that
an equivalent dose of 300-360 rems was "the top dose at
TMI that we could recognize by our yardsticks." Id.

After identifying the areas where residents described
health effects purportedly related to the reactor accident,
Gunckel searched for damaged trees in those areas. As a
result of his search, he observed "lethal effects. . . in more
than 80 spruce, pine and maple trees up to 15 miles from
the TMI facility." 1993 Affidavit, at 10; App. Vol. V, at 3325.
He reported:

       Slight to severe growth inhibition and lethal (or sub-
       lethal) damage was observed in all three species. In the
       spruce, lethal effects were more easily identified since,
       when the terminal bud is killed, there are no axillary
       buds to replace it, so the top of the spruce appears as
       a dead skeleton of branches. In the pine, when the
       terminal bud is killed, the six to eight axillary buds
       develop into major branches, giving the tree an
       apparently flat top. This effect is comparable to the
       effect found in the pine trees at Chernobyl.

        Sub-lethal radiation speeds up maturation so that in
       the maples, the leaves abscise. They form a corky layer
       at the leaf base, cutting off the water supply, causing
       the leaves to fall. The inner bark contains conducting
       tubes (phloem) which transport sugars. The phloem
       tissue is made up of anucleate sieve cells with adjacent
       companion cells. These companion cells with very large
       nuclei are targeted by the radiation, die and lesions
       form in the bark. Death results over a period of time
       when the sugar supply to the older part of the tree is
       exhausted. The acute lethal dose to spruce . . . is 1,020
_________________________________________________________________

109. See p. 35 n.40 and p. 39-40, supra.

                               110
       rem [10.02 Sv]. The acute lethal dose to the apical
       meristems of white pine branches . . . is 1,000 rem[10
       Sv]. The sub-acute lethal dose for maples . . . is 3,000
       rem [30 Sv]. The maple received the same 1000 rem
       dose as the spruce or pine. . . . To have observed the
       lethal and sublethal effects near TMI, doses of this
       magnitude had to have occurred. The dose which killed
       the chromosomes in the spruce by a direct effect on
       the target . . . is the same dose as is responsible for the
       indirect effect which caused the range of slight to
       severe growth inhibition, a morphological lethal dose,
       which is the indirect effect.

1993 Affidavit, at 9-10; App. Vol. V, at 3324-25. He then
explained that "[t]he doses which caused injury to the
nucleus of cells in plants will also injure the nucleus of
cells in animals and humans." 1993 Affidavit, at 12; App.
Vol. V, at 3327. Accordingly, he concluded that because the
damage to the trees was caused by exposure to very high
levels of radiation, the health effects suffered by the TMI
residents he interviewed "cannot be dismissed as unrelated
to the TMI accident on the a priori belief that doses were too
low." Id. Consequently, as a result of his investigation,
Gunckel offered his opinion that "during the early days of
the TMI accident, individuals received erythemic doses in
the range of 300 to 1000 rems [3 Sv to 10 Sv]." 1993
Affidavit, at 12; App. Vol. V, at 3327.

The District Court excluded all of Gunckel's proffered
testimony. It found that Gunckel's methodologies of
investigation of human health and as to his tree studies
"lack scientific validity and reliability pursuant to Rule
702." 911 F. Supp. at 810. It also found that because
Gunckel is not a medical doctor he is not qualified "to opine
as a medical expert with respect to his human . . . health
study." Id. The court also held that Gunckel's testimony
lacked "fit" because he was unable to verify that the tree
damage occurred at the time of the TMI accident, rather
than at some earlier or later date. Id. Finally, the court
found that Gunckel's dose estimates are logically
inconsistent "with the lack of human casualties in the
areas where the tree damage was noted." Id.

                               111
c. Discussion and Conclusions.

At the outset, the Trial Plaintiffs contend that the District
Court misunderstood the purpose of Gunckel's interviews of
TMI area residents who claimed to have suffered radiation
induced medical symptoms. They submit that Gunckel
sought medical information from those people, not to
render diagnoses, but rather to help him identify
geographical areas surrounding TMI where he could pursue
his hypothesis and begin to search for radiation-damaged
trees. Trial Plaintiffs' Br. at 21 n.31. They assert that the
court's Daubert/Paoli II admissibility analysis was flawed
from the start because of a fundamental misunderstanding
of Gunckel's study. We disagree.

While Gunckel's stated purpose in interviewing the
residents about their allegedly radiation-induced medical
conditions may have been as the Trial Plaintiffs claim, it is
clear that he strayed far afield from that stated purpose
and diagnosed 5 residents as having radiation-induced
erythema. App. Vol. V, at 3535-36; see also 1993 Affidavit,
at 11; App. Vol. V, at 3309 ("The fact that erythemic
responses also occurred in many cases at TMI clearly
established that there was a higher level of exposure. A
resident, in the WNW sector living about 10 miles west of
TMI at 900 feet elevation . . . experienced a classical case
of erythema from only a few minutes exposure on March
30, 1979."). Although Gunckel is a respected scientist, he is
neither a medical doctor nor a health physicist. 110 So far as
the record is concerned, his only knowledge of the health
effects of radiation was obtained from literature he reviewed
in connection with his retention as an expert in this
litigation. App. Vol. V, at 3388. He plainly does not meet
Rule 702's "Qualifications" requirement and cannot,
therefore, offer an expert opinion as to radiation-induced
medical conditions. See Paoli II, at 741.

Gunckel's opinion as to the radiation damaged trees is
less problematic, especially considering his acknowledged
expertise in the area of radiation effects on plants.
Essentially, Gunckel found trees which he claimed were
_________________________________________________________________

110. "Health physics is the name given to the study of problems related
to the protection of man from exposure to radiation." LAMARSH, at 397.

                                 112
damaged by radiation, and, using the results of his work at
Brookhaven, he extrapolated back to determine the dose
which caused the damage. At the in limine hearing, he
explained his methodology as follows:

       Q: We need to establish the relationship of your
       technique to methods which have been established to
       be reliable. Now, your technique, let's talk about your
       technique at TMI. Does that relate to reliable standards
       and methods which you used at Brookhaven? Is there
       a relationship between the two?

       A: Oh, there's a relationship. But we can't take m uch
       credit for what we did at TMI. All we did was observe
       the results. And you go backward. We did the original
       going from dose to results. All we did was observe the
       results at TMI and go to Brookhaven for the dose.

       Q: And you used, as I understand it, the informati on
       and data that you accumulated at Brookhaven to reach
       the conclusions you reached here, correct?

       A: Correct.

       Q: And I think you've already indicated that the
       Brookhaven data is very reliable, correct?

       A: Correct.

App. Vol. V, at 3516-17.

However, the District Court was critical of Gunckel's
methodology. The court stated that the "TMI tree studies
bear no functional relevance to the Brookhaven studies."
911 F. Supp. at 807. The court believed that the Gunckel's
TMI tree study bore little methodological relationship to the
Brookhaven studies because the Brookhaven studies
involved cellular and subcellular evaluations to determine
the extent of radiation damage while Gunckel's TMI tree
study involved simply observing morphological damage to
trees. Id. at 807 n.36. However, we believe that the District
Court's criticism of Gunckel's TMI tree study methodology
was inappropriate. Although the focus of the Brookhaven
radiation studies was cellular and subcellular, see App.
Vol. V., at 3485 ("our ultimate objective was to predict
doses based upon chromosome volume, or nuclear

                               113
volume."), Gunckel testified that his work at Brookhaven
also involved observing morphological damage to trees:

       Q: [D]id you have the opportunity to visibly observe the
       trees and the effects that the irradiation was having on
       them?

       A: Yeah, absolutely. This was done on a daily basi s.
       . . .

       **********************

       Q: As a result of that experience for those 20 yea rs
       that you've just discussed, are (sic) you able to visibly
       observe the radiation effects on conifers?

       A: Yes. Within the limits of those that we studied, yes.
       We didn't study them all.

App. Vol. V, at 3485-86. Consequently, so long as Gunckel
could demonstrate that his work at Brookhaven involved
mature trees, and not tree seedlings, and that he performed
differential diagnoses on the trees he studied at TMI to rule
out other causes for the damage he observed (both of which
he did)111 Gunckel's TMI tree study methodology is not as
flawed as the District Court believed.

Gunckel's methodology lies in its novelty. It has,
apparently, only been used in this litigation. Gunckel
candidly admitted that during his years at Brookhaven he
never worked in reverse to determine dose from observed
damage. He testified:

       Q: I appreciate that you have spent your professio nal
       career studying the effects of a known amount of
       radiation on the development of trees. Have you ever,
       in your professional career, tried to do the reverse and
       test it? In other words, try to infer a dose from what
_________________________________________________________________

111. There was a factual dispute in the District Court as to whether the
Brookhaven study involved mature trees, as opposed to seedlings, and
whether Gunckel performed differential diagnoses on the trees he
claimed were damaged by radiation to rule out other causes for the
damage, most notably insects and certain fungi. However, the district
court resolved that factual dispute in Gunckel's favor. 911 F. Supp. at
808; 809.

                                114
       you see in a tree and then test it to see if your inferred
       dose was reasonably accurate?

       A: No. We didn't get that far. It took us 20 years to get
       this other data together. This is not an easy thing to
       do. We simply hadn't gotten that far. And then Arnold
       Sparrow up and died in the midst of all this, so that
       ended the whole project.

App. Vol. V, at 3392. However, the quality of a given study
does not necessarily correlate to the novelty of its
methodology. Gunckel's TMI tree study is rooted in the kind
of methodology that gives his study validity and reliability,
notwithstanding the novelty of what he did, or the fact that
his study was undertaken for this litigation. If the
Brookhaven studies demonstrate that irradiation in the
amount of dose a will result in z amount of radiation
damage to a tree, we believe that a scientist of Dr.
Gunckel's renown (20 years of his professional life studying
the effects of known amounts of irradiation on trees at
Brookhaven) can certainly observe damaged trees and
determine the dose of radiation necessary to cause the
observed damage, so long as adequate and competent
differential diagnoses are performed.

Defendants argue that Gunckel's methodology is
unreliable because it is impossible to determine dose from
observed damage. In support of that argument, they cite
Gunckel's collaborator at Brookhaven, Dr. Sparrow, who
was of the opinion that while "stunted or dwarfed plants,
misshapen organs, or mottled flowers or leaves are often
the results of radiation . . . . external examination of such
abnormal plants will provide very little information as to the
basic cause of these effects." Arnold H. Sparrow,
Brookhaven Lecture Series, The Role of the Cell Nucleus in
Determining Radiosensitivity, May, 16, 1962, at 1. However,
this apparent dispute between the two collaborators does
not render Gunckel's methodology unreliable. The dispute
goes to the weight to be afforded Gunckel's expert opinion,
not the reliability of his methodology. In a Daubert/Paoli II
analysis, the focus is not on determining "which of several
competing scientific theories has the best provenance."
Ruiz-Troche v. Pepsi Cola of Puerto Rico Bottling Co., 161
F.3d 77, 85 (1st Cir. 1998). Rather, we focus on

                               115
determining whether the "opinion is based on valid
reasoning and reliable methodology." Kannankeril, 128 F.3d
at 806.

No one can seriously suggest that Gunckel's work at
Brookhaven was not good science. We believe that the
methodology Gunckel used in his TMI tree study meets the
Daubert/Paoli II admissibility requirements in so far as
methodology is concerned. See Paoli II, at 745 n.14
(suggesting that if expert uses a methodology only slightly
different from a clearly reliable methodology, the court
should be more likely to accept the altered methodology
than if it was evaluating the altered methodology as an
original matter).

That is not to say, however, that the District Court
abused its discretion in excluding Gunckel's proffered
testimony. Although Daubert insisted that the focus of the
admissibility inquiry "must be solely on principles and
methodology, not on the conclusions that they generate,"
Daubert, at 595, the Court subsequently amplified that
principle in Joiner. There, the Court wrote:

       conclusions and methodology are not entirely distinct
       from one another. Trained experts commonly
       extrapolate from existing data. But nothing in either
       Daubert or the Federal Rules of Evidence requires a
       district court to admit opinion evidence which is
       connected to existing data only by the ipse dixit of the
       expert. A court may conclude that there is simply too
       great an analytical gap between the data and the
       opinion proffered.

118 S. Ct. at 519. Consequently, although principles and
methodology remain the focus of a Daubert inquiry, "this
focus need not completely pretermit judicial consideration
of an expert's conclusions." Ruiz-Troche v. Pepsi Cola of
Puerto Rico Bottling Co., 161 F.3d at 81; see also Heller, at
153; 161 (holding that district court was correct when it
questioned an expert's conclusions).

When Gunckel's ultimate conclusions are examined, it is
clear that they must be rejected, not simply because they
could not "reliably flow from the facts known to the expert
and the methodology used," Heller, at 153, but rather

                                116
because they fly in the face of reality. Gunckel's written
opinion concludes that during the early days of the reactor
accident, "individuals received erythemic doses in the range
of 300 to 1000 rems, depending upon the isotopes to which
they were exposed." 1993 Affidavit, at 12. At the in limine
hearing, Gunckel testified that although a dose of 1,000
rems was the dose to the trees in the TMI area, a dose of
300-360 rems was a "credible" dose range for humans.
App. Vol. V, at 3501. But, he admitted that a dose of 360
rems is the "official lethal dose" for humans. Id. at 3498. He
testified: "That's an LD50/60. In other words, 50 percent of
the population would die from that dose in 60 days." Id.

Thus, equivalent doses between 300 to 1000 rems are
extremely high. They are so high that such doses would
have caused deterministic effects in the population living
around Three Mile Island.112 Yet, except for Gunckel's claim
that he discovered 5 people who suffered from radiation-
induced erythema, the record does not demonstrate, and
the Trial Plaintiffs do not contend, that anyone living in the
area surrounding Three Mile Island ever reported a
deterministic effect caused by the fission product
radionuclides released from the TMI accident to any health
care provider or health care facility.113 Similarly, even
though Gunckel admitted that a dose of 360 rems is a
lethal dose, the record does not reflect an epidemic of
human casualties near the allegedly found radiation
_________________________________________________________________

112. See p. 38-40, supra.

113. The record does contain a study commissioned by the defendants
which concluded that from June 30, 1978 to June 30, 1993, there were
no increases in hospital utilization that can be attributed to the reactor
accident. See Larry R. Fosselman, A Look at Hospital Utilization Relative
to Three Mile Island 3 (July 14, 1995)(unpublished) (App. Vol. XII,
10234-38). Fosselman's report recites that he was asked "whether any
data exists which might tend to prove or disprove the hypothesis that the
TMI accident in March, 1979, produced any changes in health evidenced
by demand on the services of acute health care providers." Id. at 1. His
conclusion, based on a review of hospital utilization data and his
personal observations, is "that the March 28, 1979, Three Mile Island
accident caused no detectable adverse health effects in the relevant
seven-county area as demonstrated by hospital utilization and health
care provider reports." Id. at 5.

                               117
damaged trees.114 In fact, if these disputed dose estimates
are correct, we would expect that half of the population
around Three Mile Island would have died within 60 days
of the nuclear accident there. Obviously, that did not
happen.

Consequently, given the complete lack of any reports of
deterministic effects following the reactor accident, and the
undeniable reality that statistically significant human
casualties did not occur following the accident, Gunckel's
conclusions are not trustworthy. Thus, the District Court
did not abuse its discretion in excluding Gunckel's
testimony in its entirety.

iv. Vladimir Shevchenko.

a. Qualifications.

Shevchenko is a scientist from the former Soviet Union
who has a Ph.D. in Biological Sciences. His area of
expertise is radiation genetics, with particular emphasis on
the cellular and subcellular effects of radiation on plants.
App. Vol. VI, at 4519. He also has experience in cytogenetic
studies on chromosomal aberrations in human
lymphocytes. Id. at 4199. From 1962 to the present, he has
studied the effects of ionizing radiation on plants and
animals in the Eastern Ural Radiation Belt, the site of a
nuclear accident which occurred in 1957 at the Mayak
military plant where atomic weaponry was produced. Id. In
addition, he has studied radiation effects on plants and
animals in the Chernobyl region since shortly after the
nuclear accident there in 1986. Id. Since 1993, he has
_________________________________________________________________

114. Gunckel attempted to explain that while the lethal dose for humans
is 360 rems, the "lethal" dose is not really lethal. He testified: "The
official lethal dose for humans is 360. . . . But that isn't people.
That's
the other thing you have to watch. That's laboratory animals. And you
can't do experiments on people and get data like that. So that's the
reason why you can't dwell on these so-called lethal doses or even think
for a moment that they are lethal. They aren't." App. Vol. V, at 3498.
However, even assuming arguendo that the reported lethal dose of 360
rems is imprecise, the absence of any reported deterministic effects
would still undermine Gunckel's conslusion to the extent that we doubt
it could survive a Daubert inquiry even then. 360 rems is undeniably an
extremely high dose even assuming that it is not lethal.

                               118
participated in a study of the people and the environment
at the Semipalatinsk Nuclear Testing Grounds where people
were exposed to ionizing radiation as a result of nuclear
weapons testing. Id. He has been Scientific Advisor to the
Russian Parliament on the effects of the Chernobyl
accident, Chairman of the Radiation Genetics Section of the
Scientific Council on Radiobiology of the Russian Academy
of Sciences, and Advisor on Radiation Genetics to the
United Nations. Appellants' Br. at 27. Shevchenko received
the Red Banner Award for his work on the Chernobyl
accident that is an honor received by only four other
members of the Russian Academy of Sciences. Id. at 28.
The District Court acknowledged that "[l]ikely more than
other expert before the court, Professor Shevchenko has
had extensive first-hand experience examining the effects of
radiation exposure." 911 F. Supp. at 816.

Shevchenko's expert opinion testimony covered two
distinct areas. The first area dealt with his morphological
study of trees in the Three Mile Island area which he claims
were damaged by radiation from the reactor accident,
together with his radiation dose estimates based on the
observed damage. The second area was his testimony about
the substance of a cytogenetic analysis performed by a
colleague, Dr. Galina Snigiryova, the head of the
Cytogenetic Laboratory of the Moscow Institute of
Diagnostic Surgery, on blood samples of a group of Three
Mile Island area residents.115 Based on Snigiryova's
cytogenetic analysis, Shevchenko used a regression curve
_________________________________________________________________

115. According to the Trial Plaintiffs' plan, Shevchenko was to testify
not
only about Snigiryova's cytogenetic analysis, but also about the tests and
reports prepared by, inter alia, Gennady Kozubov and Olga Tarasenko,
both of whom are scientists from the former Soviet Union and were
apparently recruited by Shevchenko to provide expert reports. Trial
Plaintiffs' Br. at 26-27. The District Court found that the substance of
Snigiryova's report was within the area of Shevchenko's expertise and he
was, therefore, permitted to testify about it. 911 F. Supp. at 811.
However, the court found that the substance of Kozubov's and
Tarasenko's tests and reports was outside the area of Shevchenko's
expertise. Thus, he was not permitted to testify about their tests. Id. As
it turned out, both Kozubov and Tarasenko were called as witnesses at
the in limine hearings. Their testimony is discussed infra.

                               119
to arrive at radiation dose estimates. Each area of his
proffered testimony is discussed separately.

b. Shevchenko's Tree Study.

Shevchenko's tree study is contained in an affidavit he
prepared on July 6, 1994.116 App. Vol. VI, at 4198-4211. In
it, he states that he visited the Three Mile Island area for a
three week stay beginning on June 18, 1994.117 Id. at 4198.
During that time, he conducted a morphological study of
radiation-damaged trees in various areas around Three Mile
Island. Id. In addition, Shevchenko met with James
Gunckel and he and Gunckel conducted a joint study of
radiation-damaged trees in the area. Id. Shevchenko and
Gunckel "discussed in depth the possible causes" of the
damage to the trees. Id.

The starting point of Shevchenko's tree study is his belief
that there are several woody plants which can be used as
long-term "indicators" of "relatively high exposures from
radionuclide emissions." Id. at 4202. His belief is based on
his own studies of plants and trees in those areas of the
former Soviet Union where there have been known
radiation releases, and "definitive dose data from the
Brookhaven Gama Field." Those woody plants are pine,
spruce and maple trees. Id. at 4206.
_________________________________________________________________

116. Shevchenko's Affidavit is captioned "Affidavit of Vladimir R.
Shevchenko, Ph.D., Dr. Sc., Concerning the Dose to Any Individual from
the TMI Unit Accident." In addition to discussing radiation-damaged
trees, the affidavit contains a discussion of radiation sickness and
disease allegedly suffered by TMI area residents, together with a
discussion of radiation-induced illnesses and death suffered by animals
in the TMI region. Further, the affidavit concludes with Shevchenko's
dose estimates, not simply as to the trees he studied, but also as to the
humans and animals in the TMI area. The district court did not mention
the human and animal references in its analysis of this area of
Shevchenko's expert testimony. Thus, we assume that the Trial Plaintiffs
did not proffer Shevchenko as an expert competent to give testimony
about dose estimates to humans. In addition, the Trial Plaintiffs' brief
does not mention those aspects of Shevchenko's affidavit. Consequently,
we assume that the focus of our inquiry is only on Shevchenko's tree
study.

117. Shevchenko had a follow-up visit to the area in January of 1995.
App. Vol. VI, at 4214.

                               120
According to Shevchenko, the most significant
morphological change in the pine tree in response to a
lethal exposure to ionizing radiation "is related to the death
of the terminal bud in the main leader shoot." Id. at 4202.

       This change   removes the apical dominance of the
       leader over   the most apical 6 or 7 axillary buds when
       then formed   short, multi-budded lateral branches and
       resulted in   a tree with an easily identifiable,flat, bushy
       tree top.

Id. Shevchenko claims that spruce trees are more sensitive
to radiation than pine and that exposure to high levels of
ionizing radiation "causes death of all terminal buds,"
which "causes the tree top to look like a skeleton made of
branches." Id. at 4203. At the dead top of the spruce tree,
"lateral buds able to renew growth likely do not exist, so
that it is easy to identify such trees visually." Id. In the
maple tree,

       [t]he phloem companion cells on the inner bark are the
       most sensitive to ionizing radiation, their death being
       the cause of dead spots on the bark of the tree. This
       causes visible effects like lesions in the bark, large
       wounds on the tree trunks and the loss of bark. Maple
       trees die by indirect effect. Ionization of water by beta-
       rays will, depending on the dose, shatter the xylem,
       water-conducting vessels. When a maple tree dies
       following irradiation, it does so very gradually. First,
       the leaves in the center of the crown shrivel and die
       after one week. Next, the rest of the leaves develop
       anthocyanins, develop fall coloring within a few weeks,
       and then the leaves dehisce more or less normally but
       only after about 4-6 weeks. In the spring, shoots in the
       middle or lower part of the crown are slow to develop
       sparse leaves and lesions appear in the bark. Thus, the
       main indicators of radiation damage which can still be
       observed 15 years after the accident are wounds on the
       surface of the bark. Such wounds have a typical
       appearance and are easily identified. . . . Often such
       trees have dry branches and dry tops.

Id. at 4204-05.

                                 121
In the course of his morphological tree study,
Shevchenko "observed damaged spruce, pines and maples"
and concluded that irradiation "is the cause of the full
spectrum of the observed morphological anomalies." Id. at
4206. He opined:

        It is important that in some places which were
       affected by the radioactive cloud after the accident,
       simultaneous damage to spruce, pines and maples as
       well as to other trees was observed, which is evidence
       of ionizing radiation effects. The radiation damage to
       each tree is morphologically different -- damage to top
       buds, dead tree tops, flat tree tops, bark wounds. The
       presence of a whole spectrum of tree damages in the
       same area and all with a very high frequency cannot be
       explained by anything but the effects of ionizing
       radiation exposure.

Id. Finally, he gave a dose estimate based on his
observations of the tree damage. In his "professional
opinion . . . the cases of tree damage. . . in the TMI region,
based on results of my personal observations . . ., are
related to the effects of ionizing radiation in doses of about
200 to 1,000 rem [2 Sv to 20 Sv]." Id. at 4211.

Initially, the District Court held that the tree study and
the dose estimates were admissible. 911 F. Supp. at 816-
817. Although the court conceded that the defendant's
objection was well-founded, the court concluded that
Shevchenko's experiences in studying first-hand the effects
of ionizing radiation trumped any technical deficiencies in
his methodology. The court wrote: "[W]hat his testimony
may lack in rigid conforming to technical standards is
amply counterbalanced by his extensive experience." Id. at
817.

Shevchenko's methodology was further attacked in a
motion for reconsideration. Once again, the court conceded
that the challenge to the methodology was "accurate and
insightful." In re TMI Litigation Cases Consolidated II, 922
F. Supp. 997, 1014 (M.D. Pa. 1996). Nonetheless, the
District Court found that Shevchenko's expertise and
experience were sufficient to overcome methodological
deficiencies, primarily because the proffered testimony

                               122
satisfied Rule 702's helpfulness or fit requirement. Id. The
court found:

       Because of his first-hand experience, Professor
       Shevchenko's observations will be helpful to the trier of
       fact. Even if Professor Shevchenko were to do nothing
       more than to verify that he observed radiation damaged
       trees in the former Soviet Union, and note that the
       damage he saw in the TMI area was consistent with his
       observations of tree damage in the former Soviet Union,
       his testimony would assist the jury in determining
       whether it is more likely than not that the TMI area
       was contaminated during the TMI accident.

Id.

Shevchenko's dose estimates did not fare so well on
reconsideration. In a nutshell, the court found that it was
unable to determine Shevchenko's dose estimate
methodology. The court wrote:

       The most certain thing that the court can say regarding
       the dose calculations derived from the tree study
       methodology is that after reading all of Professor
       Shevchenko's reports, deposition testimony, and the
       hearing transcripts, the court is unable to define the
       precise steps of his methodology. Each time Professor
       Shevchenko states his methodology Defendants
       challenge a component of that methodology and
       Professor Shevchenko alters the methodology to rebut
       the challenge. It is axiomatic that such methodological
       fluctuations are not scientific. . . . A purportedly
       scientific opinion that constantly changes merely to
       avoid critique can hardly be said to be based upon
       "good grounds."

Id. at 1015. Consequently, the court granted the motion for
reconsideration insofar as it challenged dose estimates and
excluded Shevchenko's proffered dose estimate testimony.

c. Discussion and Conclusions.

We are troubled by the District Court's exclusion of
Shevchenko's dose estimate testimony based on its inability
to determine Shevchenko's dose estimate methodology. The
court found that Shevchenko could testify "as to the

                                 123
observations he made of damaged trees in the TMI area and
to his comparison of the damage observed here with tree
damage at radiation exposed sites in the former Soviet
Union," Id. at 1015, but that he could not offer dose
estimates based on his tree study. In other words, the court
found that Shevchenko could testify that he found radiation
damaged trees near TMI, but that he could not draw any
conclusions as to the radiation dose which caused that
damage.

As noted above, the court's reason for excluding
Shevchenko's dose estimates was its stated inability to
divine Shevchenko's dose estimate methodology. However,
we do not believe that it is as difficult to determine that
methodology as the District Court concluded. Shevchenko
found three species of trees in the vicinity of TMI which he
claims were damaged by ionizing radiation, and he then
compared them with trees of the same species which he
believes to have been damaged by ionizing radiation in the
former Soviet Union. As noted above, those species are
pine, spruce and maple. At least with regard to pine and
spruce, Shevchenko referred to studies of radiation
damaged trees around Chernobyl where, presumably, dose
exposures had been calculated. Shevchenko's affidavit
noted that, as a result of the studies in the former Soviet
Union, the "frequency of morphological anomalies of pines
in the Chernobyl accident area was observed in 1986-1987
where exposures were from 200 -400 R (2.0 to 4.0 Gy)."
App. Vol. VI at 4202. Additional studies in the Chernobyl
area demonstrate that "the lethal dose" for spruce is about
1000 R (10 Gy)," and "[e]xposure of 3.5 to 4.0 Gy causes
death of all terminal buds of spruce trees." Id. at 4203.

Given that data, we can identify Shevchenko's dose
estimate methodology. He simply compared the degree of
damage to certain trees in the TMI area with the degree of
damage to the same species of trees in the former Soviet
Union. If the degree of morphological damage was similar,
Shevchenko used the dose exposure estimates from the
Soviet Union trees to deduct the dose exposure necessary
to cause the similar morphological damage to the TMI area
trees. Admittedly, Shevchenko's dose estimate methodology
relies in part on his own ipse dixit, rather than on

                                124
something more readily verifiable, and, in that regard, it is
open to attack. See Daubert v. Merrell Dow Pharmaceuticals,
Inc., 43 F.3d 1311, 1315-16 (9th Cir.), cert. denied, 516
U.S. 869 (1995) ("[S]omething doesn't become`scientific
knowledge' just because it's uttered by a scientist; nor can
an expert's self-serving assertion that his conclusions were
`derived by the scientific method' be deemed conclusive.
. . ."). However, Shevchenko's methodology also relies
heavily on his "first-hand experience examining the effects
of radiation exposure." 911 F. Supp. at 817. It is this first-
hand experience which the District Court weighed heavily
in favor of admitting Shevchenko's tree study. In our view,
the dose estimate methodology is simply the next
sequential step up from the tree study methodology.
Inasmuch as the dose estimate methodology flows logically
from the tree study methodology, we believe that the
District Court's conclusion that the dose estimate
methodology was based on inadequate methodology was
inappropriate.

Similarly, to the extent that the District Court's exclusion
of the dose estimates was based on the court's belief that
Shevchenko's methodology changed in response to
challenges, see 911 F. Supp. at 1014, the exclusion was
also inappropriate. If Shevchenko's methodology did change
to meet Daubert challenges, those changes strike at the
heart of Shevchenko's credibility as a witness and the
weight to be afforded his testimony. See Ambrosini v.
Labarraque, 101 F.3d 129, 141 (D.C. Cir. 1996) (District
Court improperly conflated the questions of admissibility of
expert testimony and the weight appropriately to be
accorded such testimony by a fact finder).

Nonetheless, we do not believe that the court abused its
discretion in excluding Shevchenko's dose estimates.
Shevchenko's dose estimates suffer from the same infirmity
as Gunckel's. Shevchenko's dose estimates are also
extraordinarily high. They range from a low of 200 rem to
a high of 1000 rem. As noted earlier, deterministic effects
begin to occur at doses above 100 rem (1 Sv). See
CHERNOBYL, at 39.118 The higher the dose estimates climb
_________________________________________________________________

118. The Chernobyl PROJECT noted that deterministic effects begin above
100 rad (1 Gy). However, it also reported that "[f]or most practical

                               125
from the low of 200 rem to the high of 1000 rem, the closer
Shevchenko's dose estimates approach a point where
significant human casualties should have occurred from
acute radiation syndrome.119 That didn't happen. In short,
even though Shevchenko's dose estimate methodology may
be reliable, his conclusions based on that methodology are
not. A reliable methodology "cannot sanitize an otherwise
untrustworthy conclusion." Heller, at 155.

d. The Cytogenetic Analysis.

As noted earlier, Galina Snigiryova120 performed a
cytogenetic121 analysis on blood samples of a group of 29
_________________________________________________________________

applications, the radiation weighing factor is unity; that is, the
numerical
values for absorbed dose [rad] and equivalent dose [rem] will be equal."
Chernobyl, at 21. That is especially true where gamma (g) radiation is
alleged to be the source of the harm. The quality factor, Q, of gamma (g)
radiation is 1. Thus, the absorbed dose and the equivalent dose of
gamma (g) radiation will be equal. See p. 33-34 supra.
119. For example,

       [i]n the absorbed skin dose range of 2 to 7 GY (200 to 700 rad),
the
       hematopoietic syndrome [a subgroup of acute radiation sickness]
       may be encountered. After the prodromal period, the duration of the
       asymptomatic latent period is 1 to 3 wks. The signs and symptoms
       result from radiation damage to the bone marrow, lymphatic organs,
       and immune response. In this syndrome, rapid reduction in the
       lymphocytes and a somewhat more delayed reduction of leukocytes,
       platelets, and red cells occur. The granulocytopenia leads to
       infection, and the thrombocytopenia leads to hemorrhage. Mean
       survival is usually 2 to 6 wks, with the nadir of the various blood
       elements occurring approximately 30 days after exposure. Death
       usually results from hemorrhage and infection.

MEDICAL EFFECTS, at 280.

120. Snigiryova's qualifications as an expert were not disputed. She has
Ph.D. in Radiation Biology and, in addition to being the head of the
Cytogenetic Laboratory of the Moscow Institute for Diagnostic and
Surgery, she has carried out, inter alia, cytogenetic investigations on
people exposed to ionizing radiation following the Chernobyl accident
and on people irradiated as a result of nuclear weapons testing in the
Semipalatinsk Nuclear Testing Grounds. Curriculum Vitae of Galina
Snigiryova, App. Vol. VI, at 5102.
121. Cytogenetics is "[t]he branch of genetics concerned with the
structure and function of the cell, especially the chromosomes."
STEDMAN'S MEDICAL DICTIONARY 436 (26th ed. 1995).
126
Three Mile Island area residents.122 According to Snigiryova,
it is possible to evaluate absorbed radiation doses and to
predict resulting biological effects of radiation exposure
based on an analysis of the cytogenetic effects of ionizing
radiation on human peripheral lymphocytes.123 App. Vol. VI,
at 5103. The cytogenetic method is based on an analysis of
the frequency of chromosome aberrations in peripheral
lymphocytes. Id. Snigiryova's cytogenetic study focused
upon a chromosome aberration known as a dicentric. 124 Id.
_________________________________________________________________

122. Snigiryova's report, captioned Cytogenetic Analysis of the People
Living in the Neighborhood of TMI Nuclear Power Plant, is contained in
Vol. VI of the Appendix at 5103-5117.

123. A lymphocyte is "[a] white blood cell formed in lymphatic tissue
throughout the body. . . ." STEDMAN'S MEDICAL DICTIONARY 1008 (26th ed.
1995).

124. The Trial Plaintiffs have not provided us with an explanation of
what a dicentric is. Consequently, we refer to the report of defendants'
expert, Michael A. Bender, Ph.D., a Senior Scientist in the Medical
Department of the Brookhaven National Laboratory, who has studied
chromosome aberrations for 38 years and has "participated in the
development, verification, and application of biological radiation
dosimetry using aberrations in lymphocytes form human peripheral
blood samples since 1961." App. Vol. XII, at 9961. Dr. Bender's report
states:

       Chromosomal aberrations are generally studied in cell divisions,
       during which the chromosomes are visible in the ordinary optical
       microscope. When such divisions of peripheral lymphocytes, called
       mitoses, are examined it is possible to enumerate aberrations of
       various kinds. In mitosis each chromosome, of which there are
       normally 46 in human cells, appears as a double linear structure
       with parallel "chromatids," which will become daughter
       chromosomes after cell division is completed, still attached at a
       point along their length called the centromere. Generally speaking,
       prior to its replication before cell division each chromosome
behaves
       as a single linear structure. If the chromosome is broken and/or
       rearranged prior to replication, what are termed"chromosome type"
       aberrations result. These affect both chromatids of the chromosome
       (as a result of replication of the aberrant linear structure to
form
       daughter chromosomes). If breaks and/or rearrangements occur
       after chromosome replication, however, the individual chromatids
       behave independently, with (one trivial exception) breaks and/or
       rearrangements affecting only one of the two parallel chromatids.
       These are called "chromatid type" aberrations.

                               127
at 5109. A high frequency of dicentrics is indicative of
radiation exposure. Id. at 5109.

The residents whose blood samples were drawn for the
cytogenetic analysis were selected by counsel for the
plaintiffs; presumably based on criteria proposed by
Shevchenko. App. Vol. VI, at 4978. The blood was drawn on
two separate occasions in 1994 and 1995, and shipped to
Snigiryova in Russia. Snigiryova made short-term
peripheral blood cultures, fixed and stained them according
to standard procedures and examined the resulting slides
for chromosomal aberrations. Id. at 5103-5104.

She then counted the dicentrics in the blood samples. Of
the 29 people whose blood was subjected to the cytogenetic
analysis, she found that 22 had "[q]uantitative and
structural changes in a cell chromosome system." Id. at
5112. She also found dicentrics in 19 people and found one
cell with a threecentric in one person. Id. Snigiryova
concluded that the average frequency of dicentrics was .2
_________________________________________________________________

        Because human peripheral lymphocytes are all in a pre-replication
       stage of the cell cycle while in the circulation, their irradiation
when
       in the body results only in aberrations of the chromosome type
       when they are later caused it divide in vitro for cytogenetic
       examination; no chromatid type aberrations are induced. Thus only
       chromosome aberrations are useful as indicators of human
       radiation exposure.

        Aberrations of either the chromatid or the chromosome type may
       be simple chromosome breaks, resulting in a shortened chromosome
       or chromatid and a fragment lacking a centromere (an acentric
       fragment), or be the result of intrachanges or interchanges between
       two or more breaks in the same or different chromosomes. If of the
       chromosome type, two break exchanges may either be what
       cytogeneticists call "symmetrical," including translocations and
       inversions, or "asymmetrical," including dicentric and ring
       chromosomes. The latter are what are generally used for cytogenetic
       dosimetry, mainly because their topology is radically different
from
       that of normal chromosomes, so that they are easily and efficiently
       detected. A dicentric, as the name implies, has two centromeres
       instead of the normal one, while a ring lacks any ends.

App. Vol. XII, at 20-22.

                               128
per 100 cells, which was ten times higher that the control
value she used of 2 dicentrics per 10,000 cells examined,
obtained from a study of individuals who lived in Moscow.
Id. at 5110. Based on her cytogenetic analysis, Snigiryova
opined that the group of TMI residents whose blood she
analyzed were exposed to ionizing radiation from the TMI
reactor accident. Id. at 5112.

Snigiryova's cytogenetic analysis was contained in her
written report. She did not testify at an in limine hearing
after the admissibility of her report was challenged. Instead,
over objection, the District Court permitted Shevchenko to
offer an opinion as to Snigiryova's analysis because it found
that cytogenetic analysis was within Shevchenko's area of
expertise. 911 F. Supp. at 811.

Snigiryova's written report does not contain a dose
estimate based on her dicentric enumeration. However,
Shevchenko did make a dose estimate based on
Snigiryova's dicentric counts. Using a "calibration curve,"
Shevchenko calculated that the dose exposures among the
TMI group which was the subject of the cytogenetic analysis
ranged from 60 to 80 rems [0.6 to 0.8 Sv] for someone with
2 dicentrics per 500 cells, to 90 to 120 rems [0.9 to 1.2 Sv]
for someone with 3 dicentrics per 500 cells, and 120 to 200
rems [1.2 to 2 Sv] for someone with 5 dicentrics per 500
cells. App. Vol. VI, at 4220.

Initially, the District Court rejected the attempt to
preclude the cytogenetic study and Shevchenko's dose
estimates, holding, as it did with Shevchenko's tree study,
that Shevchenko's extensive experience "counterbalanced"
whatever his testimony lacked "in rigid conformity to
technical standards." 911 F. Supp. at 817. However, on a
motion for reconsideration, the court found that
Shevchenko's methodology of arriving at dose estimates
based on Snigiryova's cytogenetic analysis was unreliable
because too long a period of time expired between the
alleged exposure and the analysis. Id. at 1013.
Consequently, the District Court granted the motion to
reconsider with respect to Shevchenko's dose estimates and
prohibited him from estimating dose based upon
Snigiryova's cytogenetic study. Id. However, the court
denied the motion with respect to the cytogenetic analysis.

                                129
It held that Shevchenko could testify as to the substance of
the cytogenetic analysis and to the findings regarding the
presence or absence of chromosome aberrations. Id.

e. Discussion and Conclusions.

The District Court's exclusion of Shevchenko's dose
estimates based on Snigiryova's cytogenetic study presents
us with a difficult question. It is undisputed that "[a]
chromosome aberration occurs when cells are irradiated
and the chromosomes are broken and can rejoin with time
after exposure." RADIATION DOSE RECONSTRUCTION, at 52. In
fact, the enumeration of unstable chromosome aberrations
is "among the most sensitive markers for radiation
exposure." Id. at 59. Moreover, counting the number of
dicentrics is an accepted method, not simply for
determining if the subject of the analysis was irradiated,
but also for estimating radiation dose to the individual.

       Chromosome aberrations induced in . . . human
       lymphocytes have been the system of choice for a
       biologic dosimeter used to quantify the dose to which
       an individual has been exposed or to verify or
       corroborate a suspected dose exposure for which no
       physical dose measurements have been available.
       These studies used mainly a dicentric aberration. . . .

Id. (emphasis added); see also MEDICAL EFFECTS, at 55
("Dicentrics are an important biologic dosimeter."). The
enumeration of chromosome aberrations can be used to
estimate doses as low as 0.10 Gy [10 rad]. 125 Id. at 53.

However, dicentrics are unstable chromosome
aberrations whose frequency deceases with time after
exposure. RADIATION DOSE R ECONSTRUCTION, at 52.
Consequently, if unstable chromosome aberrations are
"measured within a year after acute exposure there will be
little decay and the sensitivity will allow it to serve as a
good dosimeter." Id. at 59. However, the reliability of this
indicator decreases over time. Thus, the farther away in
time from the alleged exposure, the less useful the dicentric
_________________________________________________________________

125. At lower doses and lower dose rates, the enumeration of
chromosome aberrations is unlikely to help with dose reconstruction.
RADIATION DOSE RECONSTRUCTION, at 60.

                                 130
enumeration will be as an indicator of radiation exposure
and the foundation for a dose estimate. See Id. at 53 ("It
must be kept in mind that the decay found in this end
point makes it useful only for an individual recently
exposed to radiation. Authors have reported values for the
average disappearance half-time of lymphocytes containing
dicentric and centric rings ranging from 130 days. .. to 3
years. . . ."). To circumvent the problem inherent in using
a dicentric enumeration as a method for estimating dose
exposure, stable chromosome aberrations, and more
precisely, translocations,126 are now being used as markers
for radiation exposure. Id. at 59 ("The disadvantages
associated with unstable markers are avoided when stable
markers, such as reciprocal translocations, . . . are used.").
Translocations are measured by a process called the"FISH"
(Fluorescent In Situ H ybridization)127 method and
"[v]alidation measurements made by [the FISH method]
have shown that the frequency of reciprocal translocations
in whole-body-exposed individuals is constant with time
after exposure." Id. at 60.

Here, Snigiryova's dicentric count was done 15 years
after the alleged exposure. Since dicentrics disappear over
time, the usefulness of her dicentric enumerations as a
basis to make dose estimates is open to question. She
estimated in her report that dicentrics eliminate at the rate
of approximately fifty percent per year and that cells with
_________________________________________________________________

126. See p. 127-128 n.124, supra.

127. The FISH method is also known as "chromosome painting" and is
described as follows:

       In this technique, the DNA is thermally denatured to provide single
       strands of DNA. These targeted strands are incubated with
       nontarget DNA probes that bind to the DNA sequences that are
       homologous. The target DNA is stained, and the nontarget DNA is
       counterstained. Under a fluorescence microscope the target DNA
       appears yellow, and the nontarget DNA appears red. In the case of
       a translocation, the affected DNA strand will appear to be
partially
       red and partially yellow. This method detects only a fraction of
the
       translocations, so that it is necessary to apply a multiplication
       factor to estimate total translocation frequency.

MEDICAL EFFECTS, at 65.

                               131
chromosome aberrations eliminate at a rate of
approximately fifty percent in three years. App. Vol. VI, at
5110-11. She conceded, not only that the use of her
dicentric enumeration for dose estimation was problematic,
but also that the enumeration of stable chromosome
aberrations using the FISH method was the preferable
methodology. Her report states:

        The problem of the estimation of dose radiation using
       the cytogenetic data is very problematically (sic) in this
       situation. Firstly, this is connected with the long period
       after TMI accident. In such situation it seems
       necessary to estimate stable chromosome aberrations
       in lymphocytes of peripheral blood, using FISH
       method. . . . Analysis of stable chromosome
       aberrations is more important in such situations
       because translocations owing to their special structure
       may go through mitosis without complication. It is to
       allow to find stable chromosome aberrations a long
       period after irradiation and their frequency will not
       change.

Id. at 5111. Shevchenko admitted in his deposition that the
FISH method was the preferable methodology upon which
to base a dose estimate for the TMI residents who were the
subject of Snigiryova's dicentric enumeration due to the
length of time between the alleged exposure and the
enumeration. Id. at 4585.

Nonetheless, the Trial Plaintiffs claim that Shevchenko
can make a reliable dose estimate using a dicentric
enumeration on the basis of a regression analysis. His
regression analysis is nothing more than a multiplication of
the total number of dicentrics enumerated by Snigiryova to
arrive at the higher number of dicentrics presumably
existing after exposure as a result of the reactor accident.
Id. at 4220. Of course, in the regression analysis, the
multiplier is the crucial variable. Snigiryova and
Shevchenko both opined that the frequency of dicentrics to
translocations observed soon after irradiation is equal. See
Id. at 5111 (Snigiryova: "According to some data the
frequencies of unstable (dicentrics, centric rings and
acentric fragments) and stable (translocations) aberrations
observing after irradiation are about equal.") and Id. at

                               132
4794 (Shevchenko: "The original frequency under the effect
of radiation is the same, one to one ratio has been
shown."). Consequently, because of the equality of
frequency of dicentrics to translocations at the time of
initial irradiation, a correlation between unstable dicentrics
and stable translocations can be developed and from that
correlation a ratio can be determined. That ratio can be
used to develop the multiplier in the regression analysis.

The ratio of dicentrics to translocations at the time of the
analysis is crucial to developing the correct multiplier.
Nevertheless, Snigiryova's cytogenetic analysis focused
solely on dicentrics and not on translocations. The number
of translocations in the chromosomes of the TMI residents
who were the subject of the analysis is an unknown.
Therefore, neither a ratio nor a multiplier can be developed,
and without that ratio, there can be no reliable dose
estimate. Shevchenko admitted as much in a report, dated
February 4, 1996. That report states a "ratio of
translocation frequency to dicentric frequency. . . must be
used in order to reconstruct the TMI doses using
dicentrics." Id. at 4342. Shevchenko admitted at the time
he made his dose estimate that there was no established
ratio between dicentrics and translocations for the group
studied by Snigiryova. In his February 21, 1995, report, he
wrote: "Unfortunately so far we don't know a ratio between
stable and unstable chromosome aberrations for persons
suffered from the TMI accident." Id. at 4220.

Nonetheless, despite his admission that the ratio of
translocations to dicentrics was unknown when he made
his dose estimate, Shevchenko estimated a dose range
between 60 to 200 rem based on a multiplier of 6-8. Id. at
4220. His admission that he did not know a
translocation/dicentric ratio at the time he made his dose
estimate, effectively negated the reliability of the dose
estimate. Furthermore, Shevchenko changed his multiplier
over time from 6-8 in his February 21, 1995, written report,
Id. at 422, to 5 at the in limine hearing on November 22,
1995, Id. at 4811, to 2-3 in a March 4, 1996, written
report, Id. at 4357. However, he never explained why he
changed the multiplier; and he never made a corresponding
change in his dose estimate despite the changing

                               133
multiplier. Consequently, determining what, if any role, his
regression analysis occupied in his dicentric dose estimate
methodology is problematic.

Earlier, we wrote that the District Court's exclusion of
Shevchenko's dose estimate presented us with a difficult
question. Radiation dose estimation based on dicentric
enumeration is a valid and reliable scientific methodology,
but the validity and reliability decrease as the time gap
between the alleged irradiation and the dicentric count
increases Accordingly, the fifteen year delay between the
alleged irradiation and the dicentric count here is a factor
that must be considered in determining the continued
validity of Shevchenko's dose estimate based on
Snigiryova's dicentric count. As noted earlier, Daubert does
not require that the proffered expert is correct. Paoli II, at
744. Rather, the proponent of the challenged testimony
need only demonstrate that their opinions are reliable. So
long as the expert's testimony rests upon

       `good grounds', it should be tested by the adversary
       process -- competing expert testimony and active
       cross-examination -- rather than excluded from juror's
       scrutiny for fear that they will not grasp its
       complexities or satisfactory weigh its inadequacies.

Ruiz-Troche, at 85 (citing Daubert, at 596). Thus, if the only
evidentiary hurdle was the fifteen year gap between the
alleged irradiation and the dicentric enumeration,
Shevchenko's dose estimate could, arguably, survive
Daubert/Paoli II scrutiny.

Here, however, both Snigiryova and Shevchenko
conceded the FISH method is the reliable methodology for
dose estimation where there is a long span between
exposure and the cytogenetic study. In her report,
Snigiryova wrote:

       The problem of the estimation of dose estimation using
       the cytogenetic data is very problematically in this
       situation. Firstly, this is connected with a long period
       after the TMI accident. In such situation it seems
       necessary to estimate stable chromosome aberrations in
       lymphocytes of peripheral blood, using FISH method
       (fluorescence in situ hybridization).

                               134
App. Vol. VI, at 5111 (emphasis added). And, at his
deposition, Shevchenko was asked about this statement at
his deposition. The following exchange occurred:

       Q: Do you agree with that statement?

       A: Yes. I was just trying to show that that's how the
       situation is and I was trying to show what the problem
       is.

Id. at 4585. Furthermore, Shevchenko admitted that a
known dicentric/translocation ratio for the TMI group must
be used to estimate dose using a dicentric enumeration. As
noted above, the delay here was 15 years. Given that delay
and Shevchenko's concessions, we can not say the District
Court abused its discretion in excluding Shevchenko's dose
estimates under the court's Daubert/Paoli II analysis.

v. Gennady Kozubov.

a. Qualifications.

Gennady Kozubov is a forestry engineer with a Doctor of
Biological Sciences degree. App. Vol. VI, at 5156-57. He is
the Chief Scientific Worker-Advisor at the Institute of
Biology, Komi Science Center -- Ural Division, Russian
Academy of Science. Id. at 5124. His area of expertise is
dendrology, which he defined as the "science of trees
including the systematics and morphology of woody plants."
Id. at 5158. Since 1986, he has studied the effects of the
Chernobyl accident on woody plants. Kozubov believes that
a dendrometric analysis of the growth rings of trees can
determine if the trees were damaged by irradiation and a
dose estimate can be inferred from that damage. Kozubov
performed a dendrometric analysis on wood core borings
obtained from the area around Three Mile Island. 128

b. Kozubov's Opinion.

In his written report, Kozubov relied upon his study of
irradiated trees in the Chernobyl area to conclude that
radiation at high levels can suppress the annual growth of
tree rings and that radiation at low levels can stimulate
_________________________________________________________________

128. He testified that he received a patent from the former Soviet Union
to develop this dendrometric analysis technique. Id. at 5181.

                                135
that growth. Id. at 5126-28. Although he indicated that tree
ring growth is dependent upon a number of other factors,
including precipitation, temperature, sunlight and mineral
nutrition, Kozubov opined that if a large enough sample of
trees of the same species, growing under identical
conditions except for exposure to radiation, is examined,
then the differences in their annual growth rings can be
used to infer the doses the trees were exposed to. Id. at
5126-28.

Kozubov received wood boring samples that Shevchenko
collected from the area surrounding Three Mile Island in
1995. Id. at 5128. The samples were "mostly 2 samples"
from each of 35 spruce trees and 14 pine trees, which
Shevchenko collected at a height of 1.2 to 1.5 meters. Id.
He also received 9 pine and 13 spruce samples from
Shevchenko to use as a control group. Id. at 5131.

When Kozubov received the samples he polished them so
that the annual growth rings were clearly visible. Id. at
5168. Where polishing did not clearly reveal the annual
rings, special equipment was used to enhance the visibility
of the rings. Id. The samples were observed under a
measuring microscope, starting "at the bark and going deep
into the center," and the thickness of the annual rings from
1974 to 1985 was measured. Id. All of the indicators of ring
growth were entered into a computer, average statistical
data were calculated, and a graph was constructed. Id. at
5169. Absorbed doses were then calculated on the basis of
the formula which Kozubov developed in connection with a
patent he received for his dendrometric analysis technique.

Applying this dendrometric analysis, Kozubov concluded
that (1) the spruce samples showed a "distinct inhibition of
annual wood increment" in 1979, and a "stimulation" in
1980, and thus were irradiated;129 (2) radiation doses
ranged from 0.5/0.6 to 1.9/2.0 Gy [50/60 to 190/200 rad];
(3) the irradiated trees were located mainly west and
northwest of the TMI reactor; and (4) his conclusions are
"trustworthy" because the samples subjected to the
_________________________________________________________________

129. Kozubov's report recites that he was unable to perform the
dendrometric analysis on the pine samples. The reason he could not do
so is unclear. App. Vol. VI, at 5132.

                                136
dendrometric analysis were compared to the control group.
Id. at 5137.

The defendants challenged Kozubov's opinion claiming
that he did not follow the requirements of his own
methodology. After an in limine hearing, the District Court
found that his dendrometric analysis methodology was
reliable. In re TMI Litigation Cases Consolidated II, 910 F.
Supp. 200, 203 (M.D. Pa. 1996). However, the court
excluded Kozubov's proffered testimony and his
dendrometric analysis because it did not " `fit' within the
litigation." Id. At the in limine hearing, Kozubov testified
that his dendrometric analysis, standing alone, would not
prove that the samples were irradiated. It had to be
correlated with a study of seeds, needle growth and wilting
processes of the leading shoots of the trees to confirm the
conclusions of the analysis. However, no such correlation
was undertaken. Consequently, based in large part upon
Kozubov's own concession as to the absence of critical
correlation the court held that Kozubov's testimony and his
dendrometric analysis would not assist the jury"in
determining whether or not persons (and trees) in the TMI
area at the time of the accident were exposed to radiation."
Id.

c. Discussion and Conclusions.

Kozubov's admission that the dendrometric analysis
would not by itself permit him to conclude that growth ring
variations were caused by irradiation seriously undermines
his opinion that the TMI tree samples were irradiated as
well as the reliability of his dose estimates. As a result of
his work after Chernobyl, he testified that he discovered
that tree growth becomes chaotic after irradiation, id. at
5203, presumably because irradiation changes the
metabolism of the trees. Id. The deviations caused by
irradiation can be observed in seeds, needle growth, and
wilting processes. Id. at 5204. Consequently, and
presumably to exclude other causes of observed variations
in tree ring growth, Kozubov's dendrometric analysis
methodology requires correlation. He testified:

       [W]e always say that [the dendrometric] method is only
       used with other methods. One cannot use just one
       method to give this estimate.

                                 137
        That's why in Chernobyl, we also studied the needle
       growth, also we studied growth patterns, seeds and
       also the wilting process of the leading shoots. That's
       why our estimations had a compound picture. If we
       use only this one [dendrometric] method, of course we
       will not say that this was caused by exposure.

Id. at 5204. But, no studies of seeds, etc. were done by
Kozubov or anyone else130 to confirm the accuracy of the
dendrometric analysis and the dose estimates for the
accident at Three Mile Island.

The District Court found that the missing correlation
went to the helpfulness or fit requirement of Rule 702.
However, we believe that the missing correlation affected
the essential reliability of the methodology itself rather than
its "fit," because correlation is an essential element of the
dendrometric analysis. The failure to correlate renders the
methodology unreliable and the District Court therefore
correctly concluded that the expert's testimony was
inadmissible. Paoli II, at 745 ("[A]ny step that renders the
analysis unreliable under the Daubert factors renders the
expert's testimony inadmissible. This is true whether the
step completely changes a reliable methodology or merely
misapplies that methodology.").

Moreover, the failure to correlate was not the only
misapplication of the methodology. In Kozubov's formula for
estimating doses, the coefficient of accordance,"C", is a
critical variable which is derived by measuring tree ring
increments following a known dose exposure. App. Vol. VI,
at 5128. In his report, Kozubov recited coefficients of
accordance for trees irradiated as a result of the Chernobyl
accident. Id. Those coefficients were determined at
Chernobyl by using radiation doses which were known and
measured by TLD readings. Id. at 4614. However, in a
follow up report written after his initial report, Kozubov
_________________________________________________________________

130. The Trial Plaintiffs suggest that Kozubov did not need to perform
the studies to confirm his dendrometric analysis because he could rely
on Shevchenko's and Gunckel's morphological tree studies to supply the
missing correlation. Trial Plaintiffs' Br. at 38. However, they do not
provide any record citations which show that either Shevchenko or
Gunckel made a study of seeds, needles or wilting processes.

                               138
wrote that the dose estimation formula "had a number of
restrictions, as applied to the TMI accident." Id. at 5139.
Significantly, he admitted that he did not have a coefficient
of accordance for the trees he examined from TMI.

        First of all, is the lack of reliable evidence on the
       reaction of the native species of trees to the radiation
       exposure, the impossibility of experimental estimation
       of the coefficient of accordance "C".

Id.

But, the lack of the coefficient of accordance makes the
entire dose estimation formula unworkable. Without a
coefficient of accordance, the methodology cannot produce
any dose estimate, let alone a reliable dose estimate. Thus,
Kozubov's admitted inability to arrive at a coefficient of
accordance constitutes a failure of the methodology.

We agree that Kozubov's proffered testimony should be
excluded, but our reasoning differs from that of the District
Court. Inasmuch as our differing viewpoints is rooted in
different interpretations of Rule 702, we exercise plenary
review over the District Court's interpretation of Rule 702.
See Paoli II, at 749. However, here, we end up in the same
place as the District Court. We merely take a different
route. However, both routes result in the exclusion of
Kozubov's testimony, and we will therefore affirm the
District Court's result as to Kozubov.

vi. Olga Tarasenko.

a. Qualifications.

Olga Tarasenko is a medical doctor who has a Ph.D. in
immunology,131 and is the head of the Immuno-Diagnostic
Laboratory at the Russian Center of Molecular Diagnostic
and Medical Treatment. She participated in the study of
people exposed to ionizing radiation from nuclear weapons
testing at the Semipalatinsk Nuclear Testing Grounds, and
Trial Plaintiffs wanted her to testify about the results of an
_________________________________________________________________

131. Immunology is "[t]he science concerned with the various
phenomena of immunity, induced sensitivity and allergy." STEDMAN'S
MEDICAL DICTIONARY 856 (26th ed. 1995).

                               139
immunological study that she performed on blood samples
of 19 residents of the Three Mile Island area.

b. Tarasenko's Opinion.

Tarasenko performed a comparative immunological study
on blood samples from 5 groups of individuals. App. Vol. VI
at 5209. The five groups were: (1) 19 people allegedly
subjected to ionizing radiation as a result of the TMI reactor
accident;132 (2) a group of irradiated people who participated
in the clean-up following the Chernobyl nuclear power
plant accident;133 (3) a control group from Moscow; (4) a
group of inhabitants of Muslumovo village in the South
Ural region of Russia exposed to ionizing radiation as a
result of the Kyshtym accident;134 and (5) a group of
inhabitants of a "clean" village in the Altai region of the
former Soviet Union. Id. Her study was an attempt to
determine whether the TMI area residents exhibited
immune system depression, and if they did, to compare
their immune system parameters with the immune
parameters of people in the former Soviet Union who were
exposed to known levels of ionizing radiation. Herfindings,
contained in her written report, were as follows:

       In [the TMI group] even average characters
       substantially differ not only from generally accepted
       levels on immunocompetent cells but from the levels
_________________________________________________________________

132. Tarasenko performed her study at the request of Shevchenko and
Snigiryova. The blood samples Tarasenko analyzed were taken from the
same TMI area residents whose blood Snigiryova subjected to her
cytogenetic analysis. App. Vol. VI, at 5305.

133. The Russian word for the people who were involved in the clean-up
in the aftermath of the Chernobyl accident translates into English as
"Liquidators." App. Vol. VI, at 4220. Tarasenko testified that, with one
exception, the Liquidators whose blood she analyzed were exposed to
approximately 25 rems [0.25 Sv] of ionizing radiation. Id. at 5299.

134. Muslumovo village is located in the area where a nuclear accident
occurred in 1957 at the Mayak military plant which produced atomic
weapons. The Mayak military plant was located near the city of Kyshtym.
That area is referred to as the Eastern Ural Radiation Belt. App. Vol. VI,
at 4199-20; 5209. According to Tarasenko, the Muslumovo residents
were exposed to levels of ionizing radiation reaching 100 rems [1 Sv]. Id.
at 510.

                               140
       obtained in control groups (Moscow and Altai
       inhabitants). . . .

        A sharp disbalance of immunoregulating cells was
       revealed. This disbalance in combination with the
       disturbances mention above evidences the presence of
       mixed immunodeficite (sic) status in the [TMI group].

        Such disturbances are observed in the patients who
       use immunodepressants (widely used antibiotics,
       aspirin and other medicines can be referred to this
       group of chemicals) and suffer from cancer,
       autoimmune diseases, syndrom (sic) of chronic
       weariness and others. It is undoubtedly necessary to
       carry out a dynamic examination of all persons in[the
       TMI group], regular observation of their immune
       status, medical and prophylactic measures.

Id. at 5209-10. Her written report does not discuss the
possibility or probability that the mixed immunodeficit
status of the TMI area residents was caused by exposure to
ionizing radiation. She testified that when she did the
comparative study, her purpose was not "to interpret these
results." Id. at 5375. Rather, "it was[her] purpose to obtain
this data, to record these results." Id.

However, after her opinion was challenged,135 Tarasenko
testified at the in limine hearing that the TMI area residents'
immune system deficits that her written report associated
with the use of immunodepressents, etc., are possibly the
result of radiation exposure. Id. at 5308. She explained as
follows:

       The conclusion is this, characteristics that we have
       determined for inhabitants in the area of Three Mile
       Island, they are hardly different, show almost no
       differences or -- well, there is not quite an equivalent
       sign, but almost, almost the same as characteristics
       found for the inhabitants of Muslumovo village. . . .

       In other words, our conclusion is this, changes that we
       see in inhabitants of the Three Mile Island region are
       even deeper than in those who lived in that village and
_________________________________________________________________

135. Tarasenko's qualifications as an expert were not disputed.

                               141
       were eradiated (sic) as a consequence of the Kyshtym
       accident.

       **************************

       Our conclusion is that the immunodepression was
       found in both these groups under comparison. TMI
       group and Muslumovo group, immunodepression was
       present. The extent of immunodepression, however,
       was more prominent in the Three Mile Island accident.

Id. at 512-13; 520.

Tarasenko testified that she was able to offer an opinion
that the immunodepression that she found in the TMI area
residents could have been radiation induced because after
she provided her written report to Shevchenko, she received
"information [from Shevchenko that] allowed me to rule out
those other causes that are listed in the last paragraph of
the report." Id. at 5309. The information she received was
the summaries of the health histories of the 19 Three Mile
Island area residents whose blood she examined. Those
summaries were contained in Snigiryova's report of her
cytogenetic analysis. Id. at 5377.

The District Court excluded Tarasenko's proffered
comparative immunological study in its entirety not under
Daubert/Paoli II, but under Rule 703. The court concluded
that she "lacked the foundation to make the judgments she
did." In re TMI Litigation Cases Consolidated II, 922 F.
Supp. 997, 1024 (M.D. Pa. 1996). Consequently, the court
held that Tarasenko's "conclusions are not based upon
`good grounds' and are not scientifically reliable." Id.

c. Discussion and Conclusions.

Although the "primary locus" of the District Court's
gatekeeping role is Rule 702, a court "should also be
mindful of other applicable rules," Daubert , at 590; 595,
when conducting a Daubert analysis. Rule 703 provides:

       The facts or data in the particular case upon which an
       expert bases an opinion or inference may be those
       perceived by or made known to the expert at or before
       the hearing. If of a type reasonably relied upon by
       experts in the particular field in forming opinions or

                                 142
       inferences upon the subject, the facts or data need not
       be admissible in evidence.

Fed. R. Evid. 703.

Rule 703 thus focuses on the data underlying the
expert's opinion. Paoli II, at 747. It permits experts to rely
on hearsay so long as that hearsay is of the kind normally
employed by experts in the field. Id. (quoting In re "Agent
Orange" Product Liability Litigation, 611 F. Supp. 1223,
1245 (E.D. N.Y. 1985)). Therefore,

       when a trial judge analyzes whether an expert's data is
       of a type reasonably relied on by experts in thefield, he
       or she should assess whether there are good grounds
       to rely on this data to draw the conclusion reached by
       the expert.

Id. at 749. If the data underlying the expert's opinion are so
unreliable that no reasonable expert could base an opinion
on them, the opinion resting on that data must be
excluded. Id. at 748. The key inquiry is reasonable reliance
and that inquiry dictates that the "trial judge must conduct
an independent evaluation into reasonableness." Id. Rule
703's reliability standard is similar to Rule 702's reliability
requirement, i.e., "there must be good grounds on which to
find the data reliable." Id.

The Trial Plaintiffs claim that the information Tarasenko
received from Shevchenko was the medical history
summaries of the 19 people whose blood was the subject of
her immunological study. While admitting that the
information consisted of incomplete summaries, not
complete hospital or medical records, the Trial Plaintiffs
claim that the summaries contained a considerable amount
of reliable information that Tarasenko could reasonably use
to rule out the other causes of immunodepression noted in
her written report, and thus allow her to conclude that the
immunodepression was caused by ionizing radiation. They
point to Tarasenko's testimony that the summaries
included information regarding

       presence or absence of autoimmune diseases . . .[the]
       presence or absence of oncological cancer diseases,
       whether [the person] was a smoker or nonsmoker, and

                               143
       if he was a smoker what was the extent of smoking,
       then [the person's age], then a list of major diseases, as
       well as complaints.

App. Vol. VI, at 5375-77.

These summaries were the only information that
Tarasenko had about the health histories of the people
whose blood she examined. Id. at 5377; 5383. Although
Tarasenko received these summaries from Shevchenko,
they were not made by Shevchenko, nor were they based on
medical or hospital records. Instead, the summaries were
made by employees of Trial Plaintiffs' counsel, and they
were based on interviews those employees had with the
people whose blood samples were taken for Snigiryova's
cytogenetic analysis. Id. at 4576. Apparently, the interviews
were based upon questions formulated by Shevchenko. Id.136
Nonetheless, the summaries were made for litigation, not
for the purpose of obtaining medical treatment. There is
nothing improper about a medical report prepared solely for
litigation. Paoli II, at 762. However,

       a physician who evaluates a patient in preparation for
       litigation should seek more than a patient's self-report
       of symptoms or illness and hence should either
       examine the patient or review the patient's medical
       records simply to determine that a patient is ill and
       what illness that patient has contracted.

Id. In Paoli II we concluded that where the physician who
had been retained strictly for litigation purposes based
pathological causation on nothing more than a plaintiff 's
self-report of an illness, the District Court's exclusion of the
resulting evidence did not constitute an abuse of discretion.
Common sense alone suggests that such evidence is"based
on an unreliable source of information." Id.

That rationale applies here. The medical history
summaries generated by the interviews for submission to
Trial Plaintiffs' expert witnesses were unreliable and
Tarasenko did not have good grounds to rely on them to
_________________________________________________________________

136. At his deposition, Shevchenko testified that "[a]t the moment when
the blood was taken, the information was taken from the participants
according to my scheme."

                               144
arrive at her conclusion that the immunodepression her
comparative study revealed was caused by ionizing
radiation. Tarasenko should have done more. She should
have either reviewed her study subjects' medical and
hospital records or examined the subjects herself. See Id.
("[G]enerally, a doctor needs one reliable source of
information showing that the plaintiff is ill and either a
physical examination or medical records will suffice -- but
the doctor does need at least one of these sources."). She
cannot rely on medical summaries prepared from interviews
conducted by nonprofessionals as Tarasenko did here. This
is especially true when the nonprofessionals are aligned
with counsel for one of the litigants. In fact, in Tarasenko's
initial report, she said that in order to arrive at an opinion
as to the cause of the immunodepression, it is
"undoubtedly necessary to carry out a dynamic
examination of all persons [in the TMI group], regular
observation of their immune status, medical and
prophylactic measures." App. Vol. VI, at 5210. We agree.
Tarasenko's own report thus demonstrates that the data
supporting her challenged opinion were not reliable, and
the District Court did not abuse its discretion in excluding
her testimony.

vii. Bruce Molholt.

a. Qualifications.

Bruce Molholt earned a B.A. in mathematics from
Hendrix College, a M.S. in microbiology from the University
of Arkansas School of Medicine and a Ph.D. in microbiology
from Indiana University. He did post-doctoral work in
molecular biology and genetics at the University of
Stockholm in Sweden, the University of Ghent in Belgium,
and the University of Heidelberg in Germany. He taught
immunology at the University of Kansas from 1960 to 1972
and at the Medical College of Wisconsin from 1976 to 1978.
He was a Superfund toxicologist with the Environmental
Protection Agency from 1984 to 1988. He has been a
Visiting Professor in the Environmental Studies Program at
the University of Pennsylvania since 1988. In addition, he
is a principal in, and the Program Director of, Risk
Assessment and Toxicology at Environment Research
Management, Inc. App. Vol. VII, at 5412-5413.

                               145
The Trial Plaintiffs characterized Molholt as an expert in
two separate areas -- toxicology137 and risk assessment.138
He was proffered to render opinions as to dose exposure
and medical causation.139 Id . at 42.

b. Molholt's Opinions.

Molholt's first report (which the Trial Plaintiffs'
characterize as his "Dose Exposure Report") was dated April
8, 1993. It is in the form of an affidavit and is untitled. Id.
at 5424-5433. In it, Molholt opined that "[l]ymphocyte
depression is the major sequela of radiation exposure," and
therefore, "the pattern of depressed lymphocyte production
_________________________________________________________________

137. Molholt defined a "toxicologist" as"a scientist who evaluates the
relationship between exposure to potentially hazardous substances and
the onset of certain diseases." App. Vol. VII, at 6336.

138. Molholt defined "risk assessment" as follows:

        Whereas toxicology is qualitative, that is, does a certain
substance
       have an inherent property which can cause disease, risk assessment
       takes it one step further. It attempts to quantify that
relationship.
       That is, how much exposure to a toxic substance will cause disease;
       or if a disease is present, could this have been due to a given
       exposure to toxic substances knowing the amount of exposure.

App. Vol. VII, at 6336. To illustrate the difference between toxicology
and risk assessment, Molholt offered the following:

       [T]oxicology is saying that if you are exposed to arsenic, you may
       develop mental insufficiency. If you are exposed to
trichloroethylene,
       you may suffer liver damage. That is the discipline of toxicology.

        Risk assessment takes arsenic and says you must be exposed to
       ten milligrams per kilogram of soil for ten days, then you are at
risk
       for these central nervous system difficulties. . .. [Risk
assessment]
       tends to quantify not only what the level of exposure that is
required
       for the onset of a certain disease, but then you are at risk for
that
       disease with a hundred percent assurance, fifty percent assurance.

        Or in the carcinogenic realm, a whole different paradigm. And that
       is, if you are at risk from a certain exposure, what is your
individual
       probability of risk put in a probabilistic formula.

Id. at 6344-45.

139. Molholt's expertise as a toxicologist and a risk assessor were not
disputed.

                               146
. . . may be used as a long-lived form of human dosimetry140
to back-calculate the intensity of population exposures
during radiation exposures such as occurred during the
TMI accident." Id. at 5424-25. He noted reports by other
authors that "[d]irect measurements of circulating
lymphocyte levels in blood samples withdrawn from TMI
area residents confirm that they suffered statistically
significant lymphocyte depression following the accident."
Id. at 5428. He also noted additional reports that "TMI area
residents were found to have profound lymphocyte
depression five years following the 1979 reactor accident."
Id. at 5429. Using his back-calculation technique, Molholt
concluded that "the immunological evidence supports the
conclusion that human radiation exposures exceeded 100
rems [1 Sv] as a result of the TMI accident." Id.

Molholt's April 8, 1993, report was challenged under
Daubert, but Trial Plaintiffs submitted another Molholt
report, dated March 13,1995, before the court could rule on
that motion. Id. at 5435-5520. They characterized that
report as a "Medical Causation Report." It is entitled "Risk
Assessments for TMI Test Cases." The stated purpose of the
March 13 report was

       to examine the medical histories of each of the[Trial
       Plaintiffs'] cases and determine, with reasonable
       scientific certainty, whether or not the cancers they
       each developed following the 28 March 1979 TMI-2
       accident are more likely than not due to radiation
       exposures received as a result of the accident.

Id. at 5437. A general discussion of lymphocyte depression
occupies a significant portion of Molholt's Medical
Causation Report. Id. at 5442-48. His report also contains
a "lymphocyte profile" for each test plaintiff. He used the
profiles to determine whether the test plaintiffs' cancers
were caused by ionizing radiation. Id. at 5452-99. In his
Risk Assessment Report, Molholt identified six"parameters"
on which he "scored" each test plaintiff on a scale of one to
_________________________________________________________________

140. Dosimetry is "the science of determining radiation fields and dose to
individuals, or materials, by using any and all known types of detectors
and calculational techniques." President's Commission, Report of the
Task Force Group on Health Physics and Dosimetry 36 (1979).

                               147
three; the maximum score being 18. Using these
parameters and his scoring system, Molholt determined
that a score of 9 or above demonstrated that causation was
established with reasonable scientific certainty. Id. at 5451;
6490-94; 6572-73. Applying that methodology, Molholt
concluded that the Trial Plaintiffs "received their
carcinogenic insults as a result of radionuclides released by
the March-April 1979 accident in the Unit 2 nuclear reactor
at Three Mile Island." Id. at 5509.

When the Trial Plaintiffs filed their supplemental brief
regarding Molholt's lymphocyte back-calculation dosimetry,
they attached a third Molholt report, dated May 1, 1995,
entitled "Utilization of Scientific Methodology in the
Reconstruction of Radiation Doses to Human Receptors
During the 1979 Nuclear Reactor Accident at Three Mile
Island." Id. 5523-63. This report elaborates upon the April
8, 1993, Dose Exposure Report by providing supplemental
lymphocyte data. In it, Molholt again concluded that"the
TMI accident released radionuclides in amounts sufficient
to irradiate persons in the nearby area with <!DDAG> 100 rems."
Id. at 5523. The report also contained "an additional ten
phenomena," which Molholt referred to as "corollary
hypotheses." He opined that the presence of those
phenomena in the TMI area confirmed his dose exposure
opinion that the accident released <!DDAG> 100 rems [1 Sv] of
ionizing radiation. Id. at 5536-27.

However, despite his three reports, the Trial Plaintiffs
agreed to withdraw a portion of Molholt's proffered
testimony. During the in limine hearings Trial Plaintiffs'
counsel reported to the court:

       The subject of the defendants' briefing and attack on
       Dr. Molholt was his use of lymphocyte counts to
       attempt to back-calculate dose. . . . We were willing to
       have the [defendants' Daubert] motion granted in the
       limited aspect of the attack, which is the lymphocyte
       count, and not proffer Dr. Molholt to opine on that
       methodology.

App. Vol. V, at 4123. But, counsel indicated that Molholt
"would still be tendered consistent with other aspects of his
reports." Id. at 4124.

                                148
Not unexpectedly, a dispute arose as to what remained of
Molholt's proffered testimony once the lymphocyte back-
calculation methodology was withdrawn. Trial Plaintiffs
claimed that they only withdrew Molholt's testimony
regarding his lymphocyte methodology and its conclusions.
They insisted that they had not withdrawn Molholt's
proffered testimony on his "corollary hypotheses," in his
May 1, 1995, report.141 App. Vol. VII, at 6383-84.
Consequently, they argued that Molholt was still able to
testify about those hypotheses. The defendants disagreed
and argued that Molholt characterized his corollary
hypotheses "as evidence for clinical lymphocyte depression
and immunosuppression," and that this was exactly the
line of testimony that Trial Plaintiffs withdrew as part of the
lymphocyte back-calculation methodology. Id. at 6381.

The District Court found that the May 1, 1995 report
containing the corollary hypotheses was filed in response to
its February 14, 1995 order for additional briefing on the
back-calculation methodology. The court reasoned that
since the back-calculation methodology was withdrawn, the
May 1, 1995 report "is no longer relevant to this case."
Consequently, Molholt's May 1, 1995 report was also
excluded, leaving only his March 13, 1995 report. 922 F.
Supp. at 1026.

As noted above, Molholt's March 13, 1995 report was
entitled "Risk Assessments for TMI Test Cases." In it
Molholt concluded that each of the Trial Plaintiffs' cancers
was caused by exposure to ionizing radiation released by
the reactor accident. The District Court found Molholt's
methodology scientifically unreliable and excluded Molholt's
risk assessment and/or causation testimony in its entirety.
Id. at 1031. The District Court also found that Molholt did
not meet the reliability requirement of Rule 703. Id.

c. Discussion and Conclusions.

At the outset, the Trial Plaintiffs argue that the District
Court's exclusion of Molholt's May 1, 1995, report was error
_________________________________________________________________

141. Although not explicitly stated by the Trial Plaintiffs, their
withdrawal of Molholt's lymphocyte back-calculation methodology also
acted as a withdrawal of Molholt's April 8, 1993 expert report.

                                 149
because the May 1st report did not relate only to the
withdrawn lymphocyte back-calculation methodology. They
claim that Molholt's "corollary hypotheses" referred to in
the May 1st report constitutes a methodology, separate and
apart from the lymphocyte back-calculation methodology,
from which Molholt can derive a dose exposure estimate.
Trial Plaintiffs' Br. at 45. We disagree.

We note, as did the District Court, see 922 F. Supp. at
1025, that the cover letter to Trial Plaintiffs' counsel
accompanying Molholt's May 1st report clearly indicates
that the May 1st report is in response to the District
Court's February 14, 1995, order requesting supplemental
information supporting the use of the lymphocyte back-
calculation methodology. App. Vol. VII, at 5521. The cover
letter is compelling evidence that Molholt was responding to
the court's inquiries about the back-calculation
methodology when he submitted the subsequent report. 142
Molholt's proffered testimony about that methodology was
withdrawn by counsel. The District Court could reasonably
conclude that once the methodology was withdrawn, any
report submitted in support of that methodology was also
withdrawn. Moreover, the text of the report clearly indicates
that the corollary hypotheses do not stand as an
independent methodology for determining dose estimates.
Molholt's May 1st report states

       [my] first hypothesis, as stated in my affidavit of April
       1993, was that if persons who were near TMI at the
       time of the accident can be shown to have chronic
       lymphocyte depression and immunosuppression 5, 10
       and 15 years later, then they must have been exposed
       to 100 rems during the accident.

Id. at 5524. Molholt postulated that if hisfirst hypothesis
is correct, then decreased lymphocyte levels in peripheral
blood and increased cytogenetic damage in peripheral blood
lymphocytes should be observed in the TMI population
exposed to ionizing radiation. Id. at 5525. He opined,
_________________________________________________________________

142. The cover letter stated: "Enclosed you will please find my response
to the Court's memorandum of 14 February 1995 relating to Defendant's
(sic) motion to exclude my testimony in limine in the ongoing TMI
litigation."

                                150
therefore, that the presence of both phenomena would be a
confirmation of his first hypothesis. Id. Molholt then
reported that others have reported both decreased
lymphocyte levels and increased cytogenetic damage in TMI
area residents. Id. at 5525-26. Consequently, Molholt
concluded that the presence of both phenomena confirm
the validity of his first hypothesis. Id.

After concluding that his first hypothesis had been
confirmed, Molholt then discussed his corollary hypotheses.
Id. at 5526-5531. It consisted of "ten phenomena" which he
claimed should be expected following an exposure to <!DDAG> 100
rem.143 He claimed, again based on the reports of others,
that the ten phenomena were present and, therefore,"these
additional ten hypotheses comprise a very convincing
biodosimetry data set that radiation exposures exceeded
doses of 100 rem during the TMI accident." Id. at 5527.

The corollary hypotheses do not stand as an independent
methodology from which to arrive at a dose estimate. They
were a secondary method which Molholt used as
confirmation of his first hypothesis. The foundation for the
first hypothesis was the lymphocyte back-calculation
methodology that was withdrawn. The District Court
logically concluded that if the lymphocyte back-calculation
methodology was withdrawn, any evidence in support of
that methodology ought to be excluded. We agree, and
therefore conclude that the District Court did not abuse its
discretion in excluding the May 1, 1995 report.

Consequently, only Molholt's March 13, 1995, "Risk
Assessment for TMI Test Cases" report remained. That
report purported to be a causation report that inquired into
whether the Trial Plaintiffs' cancers were caused by ionizing
_________________________________________________________________

143. The ten phenomena the presence of which comprise Molholt's
corollary hypotheses are: (1) erythema, eye irritation, nausea, vomiting
and hair loss; (2) metallic and iodine tastes and smells; (3) radioiodines
in excess in local fauna; (4) increased neonatal hypothyroidism from
radioiodine emissions; (5) increased incidence of adult thyroid diseases;
(6) increased infectious diseases in exposed persons; (7) increased
infectious diseases in exposed animals; (8) increased incidence of
autoimmune diseases; (9) increased incidence of cancer; and (10)
radiation damage to trees. App. Vol. VII, at 5526-27.

                               151
radiation from the reactor accident. However, Molholt wrote
that the report focused "on three aspects of the histories of
each test plaintiff" rather than the "mechanisms of
radiation carcinogenesis." Id. at 5437. The three "aspects"
were:

       1. Were test plaintiffs exposed to sufficient io nizing
       radiation in 1979 to experience lymphocyte depression
       and/or immunosuppression? Blood analyses and
       decline in health status are indicators.

       2. Were there other indications by Plaintiffs of a cute
       radiation exposure at the time of the TMI-2 accident,
       such as erythema, nausea, iodine taste, etc.?

       3. Were the   test plaintiffs in areas of known radi ation
       exposure at   the time of the TMI-2 accident, i.e.,
       downwind or   in areas which have borne subsequent
       evidence of   radiation exposure such as arboreal apical
       ablation?

Id. Presumably in an effort to focus on these three aspects,
Molholt developed six "parameters" on which he scored
each plaintiff. He described the parameters as "relevant
causal criteria," and stated that he "attempted to apply four
weighted scores to" each of the six parameters," to arrive at
a "determination of cancer causality as resulting from TMI-
2 accident emissions with reasonable scientific certainty." A
score of <!DDAG> 50 percent established "reasonable scientific
certainty for causality." Id. at 5451. The six parameters are:

       Proximity to TMI -- taking into account not only the
       actual distance from Three Mile Island but whether or
       not the test plaintiff was located downwind from the
       TMI-2 reactor during the accident and for what period
       of time.

       Acute Symptomatology -- acute signs of radiation
       exposure during the accident, including erythema,
       nausea, eye or mucous membrane irritation and
       metallic taste or smell (these require relatively high
       doses).

       Radiation-Damaged Trees -- evidence of radiation
       damage in trees in the immediate area frequented by
       the test plaintiffs during the accident.

                                 152
       Lymphocyte Depression and Immunosuppression --
       the continuing degree of lymphocyte depression
       following March 1979 as well as immunosuppression
       as indicated by increased susceptibility to infections
       diseases. For two test plaintiffs, cytogenetic analyses
       are available.

       Age of Test Plaintiff at Cancer Diagnosis -- weighted
       high for youngest cases, median for 20s and 30s, low
       for 40s and 50s and negatively for <!DDAG> 60.

       Lag Time -- weighted high for <!DDAG> 5 years for solid
       tumors, 2 years for leukemias and less as time of
       diagnosis approaches 1979.

Id. at 5451. Based on the score Molholt assigned to each
trial plaintiff after weighing each parameter, he concluded
that the Trial Plaintiffs' cancers were caused by the
radionuclides released as a result of the accident. Id. at
5541; 5509.

We are at a loss to determine how Molholt scored each
parameter to arrive at his causation conclusion. In his
report, Molholt wrote that "[t]hese six contributors to causal
certainty [i.e., the parameters] are not equally weighted." Id.
But, at the in limine hearing, he testified that "in general,
and I don't mean specifically, but in general, I attempted to
weigh these six criteria equally." Id. at 6571. On cross-
examination, he attempted to explain the contradiction as
follows:

       A: [A]lthough my objective was to weigh each of these
       equally, that is, to give them one-sixth of the total --
       actually 16.6 percent of the total score, in fact, when
       there was an outstanding criterion like dicentric
       chromosome formation, that tended to overwhelm the
       other five criteria, such that if I have been in a position
       of making the 50 percent reasonable scientific certainty
       standard employed or not, in other words, if I was at
       that boundary, I would have weighed the chromosomal
       criteria more than damaged trees or more than
       lymphocyte depression or more than lag time.

       Q: So if you got a positive answer on chromosome
       abnormalities, that carried the day?

                               153
       A: If I were at that boundary between certainty an d
       uncertainty, which is the 50 percent standard that has
       been employed, at least up until Daubert and Paoli[II],
       what I was attempting to do was to quantify these
       criteria in such a way that I could, on an individual
       basis of each one of these, make a 50 percent
       determination, but then collectively to say, on that
       system of three, two, one, you have six criteria, the
       highest score is 18 if all six criteria are satisfied in
       terms of what we know about exposure requirements
       and carcinogenesis, radiation carcinogenesis.

        So if those six criteria were all satisfied to the fullest,
       you would have a score of 18. That's the highest you
       could get. The lowest you could get is, if none of them
       were satisfied at all, and that's zero. So I took nine as
       being the boundary.

       Q: And if they hit nine, then you said that's enou gh?

       A: No, I didn't. That's when I would reach into my
       basket of tricks and pull out dicentric chromosomes or
       some other characteristic that I thought deserved more
       credence than trying to equally weigh them. Now, as it
       turned out . . . I didn't have any that were nine . . . .
       They were all ten or more.

Id. at 6572-73. From this exchange, we can only conclude
that the methodology Molholt used to score and weigh his
parameters to determine causation is purely subjective.144
In order for expert testimony to meet Daubert's reliability
standard, it must be based on the methods and procedures
of science, not on subjective belief and unsupported
speculation. Kannankeril, at 805. Molholt's subjective
methodology is suspect. As quoted above, he testified that
when he was at the boundary between certainty and
_________________________________________________________________

144. Because Molholt's parameter scoring methodology is entirely
subjective it is obvious that it does not satisfy a number of the Daubert
factors. It was never peer reviewed, there is no known or potential rate
of error, there are no discernable standards governing its operation, and
it is not generally accepted. Daubert, at 593-594. Further, and
significantly, it is impossible to test a hypothesis generated by a
subjective methodology because the only person capable of testing or
falsifying the hypothesis is the creator of the methodology.

                               154
uncertainty, i.e., when according to his own scoring system
a trial plaintiff 's score reached nine, he "would reach into
[his] basket of tricks" to pull out something which he
thought deserved more weight. Not unexpectedly, he always
found something in his magical basket which caused the
score to exceed nine and pass from uncertainty to certainty.
However, we are as unimpressed with his "Felixian"145
basket of tricks as the District Court was, and we conclude
that the exclusion of Molholt's March 13, 1995 report was
not an abuse of discretion.

viii. Sigmund Zakrzewski.

a. Qualifications.

       Sigmund Zakrzewski earned a Ph.D. in biochemistry from
the University of Hamburg in Germany and has spent his
entire career in cancer research. For most of his
professional life, he was the Principal Cancer Research
Scientist at the Roswell Park Cancer Institute in Buffalo,
New York. He is presently a Professor Emeritus at the State
University of New York -- Buffalo, an appointment he had
held since 1987. App. Vol. IX, at 7912-7914. He was offered
as an expert to give his opinion as to the cause of the
cancers of the Trial Plaintiffs.146
_________________________________________________________________

145. See Felix The Cat: "Whenever he gets in a fix, he reaches into his
bag of tricks." Chris Milburn, Felix, Felix, Felix (visited Sept. 13,
1999)
http://www.primenet.com/#A1#cmilburn/#A1#felix/felix.htm>.

146. Zakrzewski is not a medical doctor, toxicologist or risk assessor.
Consequently, his qualifications to give an opinion on causation were
attacked by the defendants. The defendants also attacked his
qualifications on the grounds that none of his cancer research involved
the health effects of ionizing radiation. However, the District Court
found
that he met "the threshold requirement for qualification as an expert."
922 F. Supp. 1038, 1049 (M.D. Pa. 1996). That finding is not attacked
on appeal.

                               155
Volume 4 of 4

Filed November 2, 1999

UNITED STATES COURT OF APPEALS
FOR THE THIRD CIRCUIT

Nos. 96-7623/7624/7625

IN RE: TMI LITIGATION

LORI DOLAN; JOSEPH GAUGHAN; RONALD
WARD; ESTATE OF PEARL HICKERNELL;
KENNETH PUTT; ESTATE OF ETHELDA HILT;
PAULA OBERCASH; JOLENE PETERSON; ESTATE OF
GARY VILLELLA; ESTATE OF LEO BEAM,

       Appellants No. 96-7623

IN RE: TMI LITIGATION

ALL PLAINTIFFS EXCEPT LORI DOLAN, JOSEPH
GAUGHAN, RONALD WARD, ESTATE OF PEARL
HICKERNELL, KENNETH PUTT, ESTATE OF ETHELDA
HILT, PAULA OBERCASH, JOLENE PETERSON, ESTATE
OF GARY VILLELLA AND ESTATE OF LEO BEAM,

       Appellants No. 96-7624

IN RE: TMI LITIGATION

ALL PLAINTIFFS; ARNOLD LEVIN; LAURENCE
BERMAN; LEE SWARTZ

       Appellants No. 96-7625

ON APPEAL FROM THE UNITED STATES DISTRICT
COURT FOR THE MIDDLE DISTRICT OF PENNSYLVANIA
(Civil No. 88-cv-01452)
(District Judge: Honorable Sylvia H. Rambo)
ARGUED: June 27, 1997

Before: GREENBERG and McKEE, Circuit Judges, and
GREENAWAY, District Judge*

(Opinion filed: November 2, 1999)

b. Zakrzewski's Opinion.

Zakrzewski's report, dated September 15, 1994, Id. at
7920-31, states that in 1993 he was contacted by Trial
Plaintiffs' counsel and asked "to review cases of different
types of cancer . . . allegedly due to the release of
radioactivity resulting from the nuclear accident . . ." at
TMI-2. Id. at 7920. As a result, he reviewed"ten cases
involving two cases of chronic leukemia, two cases of acute
leukemia, two cases of thyroid cancer, one case of thyroid
adenoma (benign tumor), one case of osteogenic sarcoma,
one case of breast cancer and one case of adenosarcoma of
ovaries." Id. at 7921.147 His report details nine factors he
considered in evaluating the cases, viz., (1) the type of
cancer; (2) age of victims at the time of the accident; (3)
occupation at the time of the accident; (4) whereabouts of
the victims at the time of the accident; (5) latency period
between alleged exposure and diagnosis; (6) other cancer
cases in the neighborhood of the plaintiff 's residence or the
place of business; (7) possible exposure to carcinogens
other than radiation; (8) prior exposure to medical
radiation; and (9) any evidence, other than the victim's
disease indicating the possibility of exposure to ionizing
radiation. Id. He explained that because he is not a
physician he did not attempt to review any medical records.
Rather, he relied on the diagnosis of the physician of each
trial plaintiff 's case he evaluated. Id. He concluded that
"the four cases of leukemia . . . were most likely caused by
exposure to radiation released during the TMI accident, "
Id. at 7923, that "the three cases of thyroid cancer were
most likely caused by radioactive fallout resulting from the
_________________________________________________________________

* The Honorable Joseph A. Greenaway, Jr., United States District Court
Judge for the District of New Jersey, sitting by designation.

147. In other words, Zakrzewski reviewed the Trial Plaintiffs' cases.

                               158
TMI accident," Id. at 7924, that "the most likely cause of
[the] osteosarcoma is exposure to radioactive fallout
originating from the nuclear accident at TMI," and that
"whole body exposure to radiation" is the most likely cause
of the breast cancer and the ovarian cancer." Id. at 7926.

The District Court sustained defendants' Daubert
challenge to Zakrzewski's testimony. See In re TMI Litigation
Cases Consolidated II, 922 F. Supp. 1038, 1051 (M.D. Pa.
1996).

c. Discussion and Conclusions.

At the in limine hearing, Zakrzewski testified that the only
data he relied upon in arriving at his causation opinion
were a summary sheet for each trial plaintiff. App. Vol. IX,
at 8158. Each summary sheet contained a family history of
other diseases, as well as

       personal information about the person, age at the time
       of accident, age at the time of diagnosis, location of the
       residence and location of place of work, and of course,
       occupation, or school, and any possible other factors
       which could have caused the malignancy. And also,
       some information about personal observation, were you
       aware of the accident, did you observe any vegetation
       damage, and similar information.

Id. at 8136. The summary sheets were prepared by Trial
Plaintiffs' counsel and transmitted to him by a woman
identified as a consultant to the plaintiffs. 148 Id. at 8157-58.
Zakrzewski testified that he did not develop a methodology
for assessing causation and then request appropriate data.
App. Vol. IX, at 8158. Rather, it appears that he was
provided with the data and then constructed a
methodology. Id. at 8158-8159.

Earlier, we noted the interaction between Rule 702 and
Rule 703. The latter requires that the trial judge determine
_________________________________________________________________

148. That woman was Marjorie Aamodt, who, along with her husband
Norman, "have been identified as `consultants' to Plaintiffs in the
context
of this litigation." 922 F. Supp. at 1047. The District Court noted that
the Aamodt's are "not listed as expert witnesses and have not supplied
any expert reports for this case." Id.

                                 159
whether the proffered expert "is basing his or her opinion
on a type of data reasonably relied upon by experts." Paoli
II, at 748. Here, we cannot fault Zakrzewski for relying on
the diagnoses of the Trial Plaintiffs' physicians. He did so
because of his realization of the limitations endemic to his
lack of medical training and expertise. However, we share
the District Court's concern over reliance on the summary
sheets prepared by Trial Plaintiffs' counsel, and given to
him by plaintiffs' consultant. As the District Court noted:
"No evidence has been placed on the record as to how these
summary sheets were created." 922 F. Supp. at 1050. They
have no demonstrated indicia of reliability, and it is the
burden of the party offering the expert scientific testimony
to demonstrate reliability by a preponderance of the
evidence. Paoli II, at 744. Absent some evidence as to how
the sheets were prepared and the sources of the
information contained in them, it is impossible to assess
their reliability.

The Trial Plaintiffs do not waste any ink trying to
convince us that the summary sheets furnish adequate
support for an expert opinion. Consequently, our analysis
of this issue could end here, and we could merely affirm the
exclusion of Zakrzewski's testimony with no further
discussion. However, Trial Plaintiffs claim that Zakrzewski
did not rely solely on the summary sheets. They assert that
he also relied on the "scientific evidence" of plaintiffs other
experts in arriving at his causation opinion. Trial Plaintiffs
Br. at 56. For example, Zakrzewski assumed that the Trial
Plaintiffs were exposed to radiation and the basis for that
assumption was the dose evidence developed by others, i.e.,
damaged trees (Shevchenko and Gunckel), impaired
immunity (Tarasenko and Molholt); and anecdotal accounts
of radiation-induced illnesses (Gunckel). App. Vol. IX, at
7927-7929. Essentially, the Trial Plaintiffs attempt to show
reasonable reliance by postulating that their other experts'
opinions were sufficiently reliable to support Zakrzewski's
expert opinion. However, the reliability of those other
opinions is the focus of our entire inquiry. Trial Plaintiffs'
argument in this regard is the intellectual equivalent of
having the left hand put the rabbit into the hat so it can be
pulled out by the right hand. We have already upheld the
District Court's exclusion of the evidence Trial Plaintiffs

                               160
now seek to morph into a reliable foundation for
Zakrzewski's opinion. We conclude that the District Court
did not abuse its discretion by excluding Zakrzewski's
testimony.

ix. Theodor Sterling.

a. Qualifications.

Theodor Sterling earned a Ph.D. from the Tulane
University. He is an epidemiologist and a Professor on the
Faculty of Applied Science and School of Computing
Science at Simon Fraser University in Burnaby, British
Columbia. Sterling notes that, generally, his research is
"directed toward the understanding of the effects of
environment on human health." App. Vol. IX, at 8190. More
particularly, he reports that his "major areas of research
have been the effects of air pollutants including tobacco;
the effects of herbicides especially of mixtures of herbicides
known as Agent Orange; the effects of radiation both for
treatment of, and source of, cancer, the effects of
occupational exposures especially to asbestos, dioxins in
various forms and formaldehyde." Id.

Sterling submitted a report, dated April 25, 1995, entitled
"Analysis of the Elevated Cancer Risks Associated with the
1979 Three Mile Accident."149Id. at 8222-8243. In it, he
wrote that the "scientific hypothesis investigated is whether
the health of individuals living near Three Mile Island was
adversely affected by the accidental release of radioactivity."
Id. at 8237.

b. Sterling's Opinion.

At the in limine hearing, Sterling testified that he was
retained to perform an epidemiological analysis on certain
data from certain groups of people who lived in the Three
_________________________________________________________________

149. Sterling submitted a second report in the form of a "Supplemental
Affidavit" dated February 2, 1996. Id. at 8244-51. However, the District
Court found that Sterling's February 2, 1996 Supplemental Affidavit was
untimely filed and excluded it. In re TMI Litigation Cases Consolidated
II,
922 F. Supp. 1038, 1046 (M.D. Pa. 1996).

                               161
Mile Island area. App. Vol. IX, at 8282. His report identified
those groups150 and reported the results of his analysis:

       The Haystack Garment Workers: A cohort151 of 69
       women employed by Hesteco Manufacturing Co. and
       present at the factory premises at the time of the
       accident. Ten women have developed cancer since
       then. This number of cancers is greater than would be
       expected had the cohort developed cancer at the same
       incidence rate as a comparable group of women
       selected from the general population.

       The Harrisburg Schoolchildren: A cohort consisting of
_________________________________________________________________

150. In addition to the groups listed, Sterling's report contained an
analysis of a group of 15 female high-school aged softball players. App.
Vol. IX, at 8225. However, this group was withdrawn from Sterling's
proffered testimony. 922 F. Supp. at 1047.

151. In epidemiology, a cohort is "[a]ny designated group of persons
followed or traced over a period of time to examine health or mortality
experience." FEDERAL JUDICIAL CENTER, REFERENCE MANUAL ON SCIENTIFIC
EVIDENCE 172 (1994). In a cohort study, the epidemiologist

       identifies two groups of individuals: (1) individuals who have been
       exposed to a substance that is thought might cause a disease and
       (2) individuals who have not been exposed. Both groups are followed
       for a specified length of time, and the proportion of each group
that
       develops the disease is compared. If the exposure is associated
with
       or causes the disease, the [epidemiologist] would expect a greater
       proportion of the exposed individuals to develop the disease.

Id. at 134. Cohort studies are also known as concurrent studies, follow-
up studies, incidence studies, longitudinal studies and prospective
studies and these alternative names "describe an essential feature of the
method, which is observation of the population for a sufficient number
of person-years to generate reliable incidence or mortality rates in the
population subsets. This generally implies study of a large population,
study for a prolonged period (years), or both. Id. at 173. Cohort studies
can also be retrospective. In a retrospective cohort study, the
epidemiologist gathers historical data about exposure and disease
outcome of the exposed cohort. Id. at 134 n.35. The health effects are
identified and the date analyzed in a manner similar to that used in a
prospective study. "The observed health effects are then compared with
health effects expected based on an appropriate control population or
related to variations in estimated doses." RADIATION DOSE RECONSTRUCTION,
at 69.

                               162
       1991 students attending four Harrisburg elementary
       schools at the time of the accident. At least six of these
       students have developed cancer. This number of
       cancers is greater than would be expected had the
       cohort developed cancer at the same incidence rate as
       a comparable group of children selected from the
       general population.

       The Ten Mile Cohort: A cohort consisting of all persons
       under the age of 25 years at the time of the accident,
       living within a ten mile radius of Three Mile Island.
       This cohort showed a dramatic increase in leukemia
       incidence rates following the accident.

       First Trimester Infants: The cohort of infants born to
       mothers who were in the first trimester of pregnancy at
       the time of the accident, and who lived within a 10
       mile radius of Three Mile Island. This cohort showed a
       greater incidence of congenital malformations than a
       cohort of infants to mothers from the same region who
       became pregnant after the accident, and than a cohort
       of infants born in Atlanta from 1968 to 1979.

Id. at 8225-26. Sterling answered his hypothesis in the
affirmative. The District Court excluded Sterling's testimony
as scientifically unreliable under Rule 702. 922 F. Supp. at
1048. The court also excluded it under Rule 703, because
the court concluded that Sterling relied upon data that
experts in the field would find unreliable. Id.

c. Discussion and Conclusions.

Sterling admits that "[s]tatistical analysis of
epidemiological data is much abused." App. Vol. IX, at
8237. Nonetheless, there are methods by which the
epidemiologist can design a study to minimize, if not
entirely eliminate, bias and error.152 The REFERENCE MANUAL
_________________________________________________________________

152. Epidemiologists define "bias" in a way that differs from its ordinary
meaning. They define it as:

       [a]ny effect at any stage of investigation or inference tending to
       produce results that depart systematically from the true values.
The
       term "bias" does not necessarily carry an imputation of prejudice
or
       other subjective factor, such as the experimenter's desire for a

                                 163
ON SCIENTIFIC EVIDENCE notes that, although epidemiological
findings always involve a degree of uncertainty,

       systematic methods for assessing the characteristics of
       persons included in the study and their risk of disease
       can be used to help rule out known sources of bias
       and error. . . . The epidemiologist uses sample size
       calculations and inclusion and exclusion criteria for
       identifying exposed and unexposed groups . . . to
       reduce potential bias and error.

REFERENCE MANUAL ON SCIENTIFIC EVIDENCE, at 127. In
determining who will comprise the study group, the
epidemiologist must articulate "[a] list of criteria for
inclusion in and exclusion from the study." Id. at 138.
These criteria should be documented clearly before the
subjects are recruited for the study to ensure that no overt
or covert biases enter into the selection process." Id. The
danger inherent in not clearly articulating criteria for
inclusion and exclusion is that any biases that enter into
the selection process "could lead to erroneous inferences
regarding causation." Id.

Here, Sterling had absolutely no part in the selection of
the participants he studied. During cross-examination at
the in limine hearing, he testified that the participants in
the study groups and the data given to him was selected by
the Aamodts:
_________________________________________________________________

       particular outcome. This differs from conventional usage in which
       bias refers to a partisan point of view.

       *****************************

       The two main types of bias are selection bias, in which there is a
       systematic difference between those individuals included in the
       study and those who are not, and information bias, which involves
       error in measuring disease or exposure among those included in the
       study.

REFERENCE MANUAL ON SCIENTIFIC EVIDENCE, at 172.

Error, also called random error or sampling error,"is that due to
chance when the result obtained in the sample differs from the result
that would be obtained if the entire population (universe) were studied."
Id. at 174.

                               164
       Q: How did you go about looking for the groups tha t
       you analyzed here?

       A: We were contacted by Mrs. Aamodt and Mr. Aamodt
       who had done some additional -- had some done work
       (sic), and we were asked to calculate risks for these
       groups.

       Q: So they selected the groups and provided you wi th
       the data, and then you did the statistical calculations
       regarding the data they provided?

       A: That is correct.

App. Vol. IX, at 8284. As noted above, the Aamodts also
provided data to Zakrzewksi for his report. Apparently, they
are the eminences grises of this litigation. However, despite
the central role the Aamodts seem to have played in the
research conducted by various experts proffered by Trial
Plaintiffs, the Trial Plaintiffs failed to demonstrate that the
Aamodts were qualified to select the participants for
Sterling's study. See 922 F. Supp. at 1948 ("[T]here is no
evidence on the record from which the court can make any
judgment regarding the qualifications of the Aamodts to
create and execute the selection portion of an
epidemiological study design."). The Trial Plaintiffs have not
referred us to anything in the record from which we could
determine that the Aamodts are qualified to select the
participants and the data for a cohort study. Consequently,
the data upon which Sterling relied are woefully lacking in
Rule 703 reliability.

The absence of evidence that the Aamodts selected the
participants in the groups in a manner consistent with that
suggested by the Reference Manual on Scientific Evidence
creates a profound flaw in Sterling's methodology. There is
no way to insure that participants were not selected or
excluded in a manner that would bias the study. Moreover,
it appears that there are no articulated selection criteria
here because the Aamodts selected participants whom they
knew had cancer. The Aamodts included certain of the Trial
Plaintiffs in the selected groups. App. Vol. IX, at 8248-50.
The groups Sterling studied therefore had a built-in bias so
that a finding of increased cancer incidence was inevitable.
An epidemiological opinion based on such a study is not

                               165
reliable, and the District Court did not abuse its discretion
when it excluded Sterling's testimony.

x. Steven Wing.

a. Qualifications.

Steven Wing earned a Ph.D. in epidemiology from the
University of North Carolina in 1983 and is currently an
Assistant Professor in the Department of Epidemiology at
the University of North Carolina at Chapel Hill. 153 He
submitted two reports. The first, dated January of 1994, is
entitled, "Mortality Trends in Relation to the Accident at
Three Mile Island." App. Vol. VIII, at 6828-6840. Trial
Plaintiffs refer to this report as the "Mortality Study." The
second report, dated February 25, 1995, is entitled"Re-
Analysis of Cancer Incidence Near Three Mile Island
Nuclear Plant." Id. at 6869-82. Wing's second report is a re-
analysis of the data collected in connection with a cancer
incidence study in the TMI area conducted by Maureen C.
Hatch, an epidemiologist from Columbia University, and
others. See Maureen C. Hatch, Jan Beyea, Jeri W. Nieves
and Mervyn Susser, Cancer Near the Three Mile Island
Nuclear Plant: Radiation Emissions, 132 Am. J. of
Epidemiology 397 (1990)(hereinafter "Hatch/Susser study").
The Trial Plaintiffs refer to Wing's February 25th report as
the "Cancer Incidence Study."

Each report is discussed separately.

b. Wing's Mortality Study.

In his Mortality Study, Wing wrote that Norman Aamodt,
the plaintiffs' consultant, contacted him and asked him to
review the results of a study of mortality trends which
Aamodt had conducted. App. Vol. VIII, at 6831. According
to Aamodt's study,154 mortality trends in the five counties
_________________________________________________________________

153. Wing's qualifications as an expert were not challenged.

154. There is nothing in the record that indicates that Aamodt is
qualified to perform an epidemiological study. Aamodt's study was,
however, very elementary. Wing described it as follows:

        Aamodt conducted his epidemiological analysis using paper and
       pencil and the vital statistics data published by the Pennsylvania

                               166
surrounding Three Mile Island were higher in 1980"than
would have been expected based on the trends for earlier
and later years." Id. Aamodt suggested to Wing that "high
doses of radiation to small populations residing on the
elevated terrain in the path of the noble gas plumes from
the TMI accident lead to the deaths of some older people
who were already in poor health. . . ." Id. Wing confirmed
the results of Aamodt's mortality study and agreed to
conduct a more sophisticated study of mortality rates in the
Three Mile Island Area. Id. at 6832.

In that follow up analysis, Wing had access to
computerized records of death and population counts by
age in the five-county area. He calculated age-adjusted
death rates and isolated for specific causes of death. Id. at
6833. His analysis also included a study of mortality trends
in all Pennsylvania counties and in the continental United
States. Id. at 6834; 6836. Wing concluded that the
following major findings suggested an effect of the TMI
accident:

       1. an elevation of 1980 mortality in the five co unties
       around TMI amounting to about 490 more deaths than
       would have been expected from 1979 rates;

       2. an increase in cancer mortality among young
       children in the five counties in 1980-82;

       3. an increase of infectious disease death rates i n the
       five counties after the accident; and

       4. a geographic clustering of areas with higher-th an-
       expected 1980 mortality in parts of Pennsylvania and
       the Middle Atlantic and New England States.
_________________________________________________________________

       Department of Health. He added the annual numbers of death for
       the five counties around TMI (Cumberland, Dauphin, Lebanon,
       Lancaster and York) and divided each number by the total estimated
       population, provided by the State or computed by extrapolation, to
       form annual crude death rates. When he plotted the rates over time,
       he noted an abrupt rise in the death rate in 1980, the year after
the
       accident.

App. Vol. VIII, at 6832.

                               167
       These results, considered in the context of other
       studies and uncertainties about exposure estimates,
       may reflect mortality impacts of high-level radiation
       exposures from the 1979 accident at Three Mile Island.

Id. at 6839.

The District Court sustained the defendants' Rule 702
challenge to Wings' mortality study testimony and excluded
it following an in limine hearing. The court held that the
study doesn't "fit" as required by Rule 702. 155 In re TMI
Litigation Cases Consolidated II, 911 F. Supp. 775, 820
(M.D. Pa. 1996).

c. Discussion and Conclusions.

We agree that Wing's mortality testimony lacks the
requisite fit under Rule 702.156 Wing wrote that the "ability
of an epidemiological analysis to detect health effects of an
environmental agent depends on having good information
on exposures of individuals and the relevant biological
responses." App. Vol. VIII, at 6838. However, he conceded
that he had no information on dose exposure, and
cautioned that the results of his study "should be
interpreted in that context." Id. He seconded his own caveat
at the in limine hearing when he conceded that few specific
conclusions could be drawn between the increased
mortality his study found and the releases from the reactor
accident because he did not have any estimates of radiation
doses. On direct examination, he testified:

       Well, it's important to note that this study does not
       have any estimates of radiation doses, and it's a study
_________________________________________________________________

155. The District Court did find, however, that Wing's mortality study
met the reliability test of Daubert/Paoli II, 922 F. Supp. at 819.

156. The District Court also found that Wing's testimony would
"unnecessarily confuse the jury," and was therefore inadmissible under
Fed. R. Evid. 403. Rule 403 provides: "Although relevant, evidence may
be excluded if its probative value is substantially outweighed by the
danger of unfair prejudice, confusion of the issues, or misleading the
jury, or by considerations of undue delay, waste of time, or needless
presentation of cumulative evidence." However, because we find that
Wing's mortality testimony does not "fit," we need not review the District
Court's Rule 403 analysis.

                                 168
       simply of death rates, and as such, there are not very
       specific conclusions that can be drawn. . . . So it's not
       an analysis of the association between dose and
       mortality. It's an investigation of an observation that
       was originally made in Vital Statistics data to
       understand who experienced this in terms of the age
       groups, what causes of death in the local area showed
       this, and which did not.

Id. at 7214-15. On cross-examination, he admitted that
even though his study demonstrated an elevated mortality
in 1980, he could not attribute that elevation to radiation.157
In fact, Wing conceded that the mortality elevation was
probably influenced by other factors. On cross-examination,
the following exchange occurred:

       Q: Am I correct to understand, then, that the mort ality
       data you present may also reflect other factors?

       A: I'm quite sure other factors are reflected, y es. And I
       mean to say by that, other factors, other additional
       factors.158

Id. at 7250.

Wing's admission that his study was a mortality study
only, and not an analysis of an association159 between dose
_________________________________________________________________

157. He testified: "I can't conclude that the elevation, the observed
elevation, is due to radiation, from this study." Id. at 7250.
158. In his report, Wing wrote that one factor explaining, or tending to
explain, the increased mortality he observed in 1980 may be the
epidemics of pneumonia and influenza that occurred in the winters of
1979-80 and 1980-81. App. Vol. VIII, at 6839. However, at the in limine
hearing, Wing testified that he investigated the pattern of flu epidemics,
but "did not see any clear evidence that this was the year with the big
flu epidemic, and therefore, that's why mortality was elevated in that
year." Id. at 7251. Nonetheless, Wing held to his opinion that the
increased mortality may also reflect other factors.

159. Association is a term of art in epidemiology. It is defined as "[t]he
degree of statistical dependence between two or more events or variables.
Events are said to be associated when they occur more or less frequently
together than one would expect by chance. Association does not
necessarily imply a causal relationship. Events are said not to have an
association when the agent (or independent variable) has no apparent
effect on the incidence of a disease (the dependent variable). REFERENCE
MANUAL ON SCIENTIFIC EVIDENCE, at 171.

                               169
and mortality, combined with his admission that he was
unable to conclude that the elevated mortality was due to
radiation exposure clearly demonstrates a lack of"fit." He
does not even make a tenuous connection between the
radionuclides released during the reactor accident and the
elevated cancer mortality his study revealed. Consequently,
the District Court did not abuse its discretion in excluding
Wing's mortality testimony.160

d. Wing's Cancer Incidence Study.

As noted above, Wing's cancer incidence study is a re-
analysis of the data in the Hatch/Susser study. The
Hatch/Susser study was undertaken at the request of the
Three Mile Island Public Health Fund161 and tested "a priori
hypotheses that risks of specified cancers may have been
raised by exposure to radiation emanating" from TMI-2 as
a result of the reactor accident. Hatch/Susser study, at
398. There were 5,493 incident cases of cancer diagnosed
in study area residents from January 1, 1975, to December
31, 1985. Id. at 399-400. Hatch, Susser et al., divided the
TMI area into geographical study tracts and analyzed pre-
and post-accident cancer incidence relative to dose, both
from accident emissions and from routine plant emissions,
within those tracts.162 Id. at 400-02. The dose exposure
level used for accident emissions was very low -- an
average of approximately 0.1 Sv, with 1 mSv the projected
maximal dose. Id. at 400. Routine plant emissions were
estimated to be 0.006 mSv per year. Id.

The primary cancers Hatch/Susser, et al., considered
were leukemia163 and childhood cancers.164 However, the
_________________________________________________________________

160. The District Court viewed Wing's mortality study as a "preliminary
analysis, meant to be supplemented by further study and testing." 911
F. Supp. at 820. We agree with that view. Wing's mortality study strikes
us as more of a work-in-progress than a final epidemiological study.

161. See p. 76 n.83, supra.

162. The Hatch/Susser study dose estimates were derived from original
plant data, meteorological data from a weather station maintained at the
TMI plant, and a Gaussian plume dispersion model. Hatch/Susser
study, at 400-01.

163. Hatch/Susser excluded chronic lymphocytic leukemia, which is
considered to be nonradiogenic. Hatch/Susser study, at 400.

164. Leukemia and childhood malignancies were selected because of
"either short latency periods or sensitivity to low-dose radiation, or
both."
Hatch/Susser study, at 400.

                              170
grouping of " `all cancers' was selected for the sake of
completeness." Id. at 400. The Hatch/Susser study
concluded:

       For accident emissions, the authors failed to find
       definite effects of exposure on the cancer types and
       population subgroups thought to be most susceptible
       to radiation. No associations were seen for leukemia in
       adults or for childhood cancers as a group. For
       leukemia in children, the odds ratio was raised, but
       cases were few (n = 4), and the estimate was highly
       variable. Moreover, rates of childhood leukemia in the
       Three Mile Island area are low compared with national
       and regional rates. For exposure to routine emissions,
       the odds ratios were raised for childhood cancers as a
       whole and for childhood leukemia, but confidence
       intervals165 were wide and included 1.0. For leukemia
       in adults, there was a negative trend. Trends for two
       types of cancer ran counter to expectation. Non-
       Hodgkin's lymphoma showed raised risks relative to
       both accident and routine emissions; lung cancer
       (adjusted only indirectly for smoking) showed raised
       risks relative to accident emissions, routine emissions
       and background gamma radiation. Overall, the pattern
       of results does not provide convincing evidence that
       radiation releases from the Three Mile Island nuclear
       facility influenced cancer risk during the limited period
       of follow-up.

Id. at 397.

Wing's reanalysis of the Hatch/Susser data began with
the a priori hypothesis that the levels of radiation exposures
were higher than the levels used in the Hatch/Susser
_________________________________________________________________

165. A confidence interval is "[a] range of values within which the
results
of a study sample would be likely to fall if the study were repeated
numerous times. . . . The width of the confidence interval provides an
indication of the precision of the point estimate or relative risk found
in
the study; the narrower the confidence interval, the greater the
confidence in the relative risk estimate found in the study. Where the
confidence interval contains a relative risk of 1.0, the results of the
study
are not statistically significant." REFERENCE MANUAL ON SCIENTIFIC
EVIDENCE,
at 173.

                               171
study. App. Vol. VIII, at 6871. That hypothesis was based
on the "ongoing collection of evidence suggestive of high-
level radiation exposures in the pathways of radioactive gas
plumes." Id. Using that hypothesis, Wing reanalysed the
Hatch/Susser data based on the relationship between
cancer incidence and accident exposures characterized by a
single dose response line derived from the cancer incidence
in all of the study tracts. He focused on "incidence of all
cancers and lung cancer" and the category of"all
leukemias." Id. at 6875. The dose response line has a rising
slope when increased dose corresponds to an increase of
cancer, a zero slope when there is no change in cancer
incidence with increased dose, or a negative slope when
there is a decline in cancer incidence corresponding to an
increase in dose. Id. at 6874; 7232-32. Wing determined
the difference between the dose response lines in the pre-
accident period (1976-79) and the post-accident period
(1981-1985). Id. at 7231. Statistical analysis was then used
to derive the slope of the dose response line which best fits
the cancer incidence data across all study tracts.

Wing's re-analysis showed "that cancer rates, and
specifically lung cancer and leukemia, increased more
following the accident in areas estimated to have been in
the pathway of radioactive plumes than in other areas." Id.
at 6879. Consequently, he concluded that the increases in
cancer incidence "are consistent with allegations that the
magnitude of radiation exposures from the accident were
much higher than has been assumed in past studies." Id.

The District Court found that Wing's re-analysis was
"only marginally scientifically reliable." In re TMI Litigation
Cases Consolidated II, 922 F. Supp. 997, 1019 (M.D. Pa.
1996). However, because "marginally scientifically reliable
is not unreliable," the court found that the re-analysis met
the Daubert/Paoli II reliability standards. Id. Consequently,
the cancer incidence study was ruled admissible, except for
that portion of the study which analyzed lung cancer. 911
F. Supp. at 823. The District Court believed that the lung
cancer portion of the cancer incidence study did not meet
Rule 702's fit requirement because of the latency period for
lung cancer which Wing used in his study. Id. at 822-23.

                               172
e. Discussion and Conclusions

The District Court's exclusion of the lung cancer portion
of Wing's cancer incidence study is troublesome. Wing's re-
analysis demonstrated that cancer rates, and specifically
lung cancer and leukemia rates, increased following the
accident in those areas estimated to have been in the path
of the alleged radioactive plume. He used a minimum
latency period for lung cancer of four to eight years, and he
based that period upon a study of lung cancer in uranium
miners.166 However, the defendants' expert167 testified that
the general latency period for solid tumors, other than
thyroid cancer, but including lung cancer, is between ten
and fifteen years. App. Vol. XIV, at 11959. In addition, the
defendants claim that Wing misread the study from which
he derived his lung cancer latency period. In their view, a
correct reading of that study would demonstrate that the
latency period for lung cancer is up to sixteen years.
Appellees' Br. at 52.

The issue of the latency period for lung cancer is
important because of the time frame of Wing's cancer
incidence study. The Hatch/Susser study used incident
cancers from 1975 to 1985, and Wing used the same
incident cancers. The reactor accident occurred in 1979
and the last year covered by his study was 1985. Therefore,
the period between the accident and the last year of the
study was six years. Consequently, the ability to make a
plausible association between the accident and a diagnosis
of post-accident lung cancer depends upon the length of
the latency period. If the latency period is four to eight
years, as Wing claimed, then a sufficient latency period
elapsed between exposure and diagnosis to make a
_________________________________________________________________

166. The study is JAY H. LUBIN, ET AL., RADON AND LUNG CANCER RISK: A
JOINT
ANALYSIS OF 11 UNDERGROUNDMINERS STUDIES (U.S. Department of Health
and Human Services, Public Health Service, National Institutes of
Health, NIH Publication No. 94-3644, 1994), and is found at App. Vol.
VIII, at 7294-7310.

167. The defendants' expert who testified as to the latency period for
lung cancer was David G. Hoel. Hoel is the Professor and Chair of the
Department of Biometry and Epidemiology of the Medical University of
South Carolina in Charleston, South Carolina. App. Vol. XII, at 10352.

                                173
plausible association between the exposure and the lung
cancer. If, however, the latency period is ten tofifteen
years, as the defendants claim, then an insufficient latency
period elapsed between the date of the accident and the last
year of the study to draw a plausible association between
radiation released by the reactor accident and a diagnosis
of lung cancer.

The District Court decided to exclude the lung cancer
portion of Wing's cancer incidence study because it lacked
"fit." 911 F. Supp. at 823. It found that Wing's findings
regarding all cancers and leukemia suggest increased levels
of radiation exposure, and therefore, "fit," because they are
relevant to a fact in issue, viz., the radiation dose received
by the plaintiffs. Id. at 823. However, the court held that
"failure to explain the discrepancy between expected latency
periods and his lung cancer findings" negates his study's
fitness. Id.

We assume that the District Court believed that Wing
used an insufficient latency period between the date of the
accident and diagnoses of post-accident lung cancer and
therefore could not make an association between exposure
and onset of lung cancer. However, that finding assumes
that the latency period was ten to fifteen years as claimed
by defendants. Thus, it appears that the District Court
credited the defendants' expert over Wing. We believe that
was error.

Earlier in its analysis of Wing's cancer incidence study,
the District Court wrote that the lung cancer latency
question "decreases the credibility of Dr. Wing'sfindings."
Id. at 822. However, such credibility issues arise only after
admissibility has been determined, Kannankeril , at 806,
and they are decided by the jury. See Breidor v. Sears,
Roebuck & Co., 722 F.2d 1134, 1138-39 (3d Cir. 1983)
("Where there is a logical basis for an expert's opinion
testimony, the credibility and weight of that testimony is to
be determined by the jury, not the trial judge."). Here, by
crediting the opinion of the defendants' expert, the District
Court conflated its gatekeeping function with the fact-
finders' function as the assessor of credibility. See
Kannankeril, at 809 ("The trial judge must be careful not to
mistake credibility questions for admissibility questions.").

                               174
Consequently, we believe that it was error for the District
Court to exclude Wing's lung cancer testimony.

xi. Douglas Crawford-Brown.

a. Qualifications.

Douglas Crawford-Brown earned a Ph.D. in nuclear
science and health physics from the Georgia Institute of
Technology. He is currently a Professor at the University of
North Carolina at Chapel Hill, North Carolina, and the
Director of the Institute for Environmental Studies at the
University. He is also a member of the faculty of the
Ecology Program, and the faculty of the Public Policy
Analysis Program.168 App. Vol. V, at 3198. He was offered as
an expert in exposure assessment, which he said is a
"distinct stage[ ] of risk assessment. Id. at 3200. He defined
"risk assessment" as a

       process by which you first determine whether a
       substance or a risk agent is able to produce effects,
       and then you determine the amount of exposure or the
       amount of the substance that's in the environment,
       and then you determine the relationship between
       exposure and severity of effects. And then you
       summarize that as an estimate of the probability and
       severity of effects and uncertainty distribution in a
       distribution of variability in the population.

Id. at 3199.

b. Crawford-Brown's Opinion.

The Trial Plaintiffs characterized Crawford-Brown"as a
kind of chairperson" for their "team of experts," Trial
Plaintiffs' Br. at 16. He reviewed the reports of the Trial
Plaintiffs' other dose exposure experts and, on the basis of
that review, offered an opinion as to the radiation dose to
which Three Mile Island area residents were exposed as a
result of the reactor accident. In his February 27, 1995,
Affidavit, he opined as follows:

       Based on the . . . considerations of evidence, and
       conditional on establishing that the effects noted were
_________________________________________________________________

168. Crawford-Brown's qualifications were not in dispute.

                               175
       in most likelihood caused by radiation exposures, it is
       my professional opinion that the findings above are
       consistent with the claim that individuals located in
       the vicinity of the points of biological dosimetry
       received dose equivalents at levels in excess of 100
       rem. This opinion in based on a full consideration of
       the coherence of the evidence, with similar conclusions
       being reached across the various inference options.

App. Vol. V, at 3081. Thus, in order to give his exposure
assessment, Crawford-Brown assumed that the effects that
the other dose experts claimed (chromosome dicentrics, tree
damage, anecdotal reports of erythema, metallic taste, etc.,
increased rates of cancer post-accident) were actually
caused by radiation, and he assumed that those experts'
estimates of the dose required to produce those effects were
correct.

The District Court excluded his proffered testimony in its
entirety because it did not meet Rule 702's reliability
requirement.169 In re TMI Litigation Cases Consolidated II,
911 F. Supp. 775, 826 (M.D. Pa. 1996). The court found
that Crawford-Brown's testimony was unreliable because
"he chose to rely blindly upon the conclusions generated by
Plaintiffs other experts," rather than evaluating the "relative
strength or weakness of each of the strands of evidence
(e.g., biological dosimetry data) available to him." Id. at 825.

c. Discussion and Conclusions.

We share the District Court's concern with the reliability
of Crawford-Brown's "process or technique." He testified
that in arriving at his conclusions he relied on the opinions
of plaintiffs' other dose experts and assumed the
correctness of each expert's proposition. App. Vol. V, at
3257. For example, he did not testify that the tree damage
observed by Shevchenko and Gunckel was an effect of
_________________________________________________________________

169. The district court also found that it was inadmissible because it was
irrelevant under Rule 402. 911 F. Supp. at 826. Federal Rule of Evidence
402 provides: "All relevant evidence is admissible, except as otherwise
provided by the Constitution of the United States, by Act of Congress, by
these rules, or by other rules prescribed by the Supreme Court pursuant
to statutory authority. Evidence which is not relevant is not admissible."

                                 176
radiation. Rather, he testified that he had "to leave that to
someone else who is an expert in that area to decide." Id.
at 3237. Similarly, he testified that he accepted Snigiryova's
dicentric enumeration for the population she studied in
arriving at his dose estimate. Id. at 3212. He did not testify
that increased cancer and leukemia rates observed by Wing
in his cancer incidence study were caused by radiation.
Rather, Crawford-Brown testified "Well, again, my opinion
is conditional on another expert establishing that the
leukemia rates are due to radiation exposures." Id. at 3215.
Thus, his opinion is somewhat analogous to the last
domino in the line that begins to fall when thefirst domino
is toppled.

Crawford-Brown admitted that (unlike Kozubov) he did
not use trees for dosimetry. He testified: "If you mean has
it actually been used in dosimetry studies by people like
myself who do dosimetry, then no." Id. at 3235. He also
testified that he had never heard of a study where cancer
or leukemia rates were used to estimate dose. "I know of no
cases where that's been done. I can't imagine why
somebody would have done it. . . ." Id. at 3251. Moreover,
he testified in his deposition that he never made any
attempt to assess the validity of any of the assumptions the
other experts used to formulate their opinions.

       Q: With respect to any of the stated assumptions, do
       you make any effort to assess their validity?

       A: No. They are hypothetical in each case.

       Q: This is maybe asking the same question or a clo sely
       related question. But have you made any effort to
       assess the probability that these assumptions are true
       or not?

       A: No.

Id. at 3157.

However, by not assessing the validity of the other
experts' assumptions, Crawford-Brown ignored his own
stated principles of risk assessment. He testified that the
"risk assessment community recognizes" that"all relevant
lines of inference170 should be examined, and then there
_________________________________________________________________

170. In epidemiology, inference is "[t]he intellectual process of making
generalizations from observations. In statistics, the development of

                               177
should be a study done of the coherence across those lines
of reasoning." Id. at 3200. He further testified that a
"complete exposure assessment would look at all lines of
reasoning." Id. at 3182. In addition, he testified that in
making an exposure assessment, he would make an
assessment of the strengths and weaknesses of the
available evidence. He testified as follows at his deposition:

       Science can't distinguish between the estimates. What
       it can say is something about the relative strength of
       each of the estimates -- which ones you believe and
       which ones you disbelieve, to what degree do you
       believe them or disbelieve them.

        And then, in my work, anyway, that is then called a
       cumulative confidence distribution. You ask, now
       considering all the lines of reasoning, how confident
       are you that it's less than one rem, ten rems, a
       hundred rems, a thousand rems, and so forth. And
       that assignment of confidence at any given dose
       [estimate] depends on how much you're weighing the
       various lines of evidence.

Id. at 3108-09. However, he did not assign any confidence
to any of the assumptions he relied upon. Rather, he
explained that his testimony "really is . . . not a statement
about the complete coherence of all bodies of data, which I
think ultimately need to go into an assessment of the
exposure. And I've left that to others in this process to
integrate together. I don't see that as my role here." Id. at
3182.

Crawford-Brown's failure to assess the validity of the
opinions of the experts he relied upon together with his
unblinking reliance on those experts' opinions,
demonstrates that the methodology he used to formulate
his opinion was flawed under Daubert as it was not
calculated to produce reliable results. Thus, the District
Court did not abuse its discretion in excluding Crawford-
Brown's testimony.
_________________________________________________________________

generalization from sample data, usually with calculated degrees of
uncertainty." REFERENCE MANUAL ON SCIENTIFIC EVIDENCE, at 174.

                               178
4. Effect of the Exclusion of Wing's Lung Canc er
Testimony.

A trial court is not precluded from granting summary
judgment merely because expert testimony is admitted. If,
even given the proffered expert testimony, the proponent
"still has failed to present sufficient evidence to get to the
jury," summary judgment is appropriate. Heller, at 152
(citing Daubert, at 596); see also Paoli II, at 750 n.21.
Earlier, we concluded that the District Court abused its
discretion by excluding the lung cancer portion of Steven
Wing's cancer incidence study. Consequently, we must
determine whether the improperly excluded expert
testimony is sufficient to create a material issue of fact.
Heller, at 152. See In re TMI Litigation Consolidated
Proceedings, 927 F. Supp. 834 (M.D. Pa. 1996). 171

The District Court's grant of summary judgment in favor
of the defendants was the inevitable result of its exclusion
of the testimony of the Trial Plaintiffs' dose exposure
witnesses. At the conclusion of the Daubert challenges to
the dose experts, the Trial Plaintiffs' dose exposure
testimony rested upon the admissible testimony of four
witnesses. The District Court identified them and
summarized their admissible testimony as follows:

       [T]he Lochbaum testimony that a blowout may or may
       not have occurred, and that if one did occur, more
       than 10 million curies of noble gases were released
       from the plant during the accident; Dr. Vergeiner's
       testimony regarding how prevailing weather conditions
       may have effected plume dispersion and travel during
       the accident; Dr. Wing's cancer incidence study; and
       Professor Shevchenko's cytogenetic analysis and tree
       study.

927 F. Supp. at 863.

The court held that Trial Plaintiffs had to produce
evidence demonstrating that "it is more likely than not that
each of the Trial Plaintiffs' neoplasms were the result of
their exposure to ionizing radiation during the TMI
accident, in order to create a genuine issue of material
_________________________________________________________________

171. The District Court's summary judgment opinion.

                               179
fact." Id. at 866-87. Because the Trial Plaintiffs elected to
try their cases on the theory that they were exposed to
equivalent doses of at least 10 rems each, they had to
produce evidence of that degree of exposure. The District
Court reasoned that the crucial causation issue was the
Trial Plaintiffs' ability to produce admissible source term172
evidence. Id. at 867. However, at the time of the summary
judgment motions, the Trial Plaintiffs had no admissible
source term evidence. Id.

The only possible source term evidence was Lochbaum's
equivocal "blowout" testimony, which the District Court had
earlier determined would be admissible only if the Trial
Plaintiffs' other experts could demonstrate that significant
amounts of radionuclides were released as a result of the
accident. 922 F. Supp. at 1052. However, because of earlier
exclusionary rulings there was no other admissible source
term evidence, and, consequently, the District Court found
that "there is insufficient dose evidence . . . to make
Lochbaum's testimony helpful to the trier of fact." 927 F.
Supp. at 867. The District Court also found that
Lochbaum's blowout testimony was so equivocal that it
"lacked the certainty of a professional judgment" and was,
therefore, insufficient to defeat a motion for summary
judgment."173 Id. at 868. Consequently, the District Court
found that the Trial Plaintiffs did not demonstrate that the
reactor accident released high concentrations of radioactive
materials to the environment. Id. In brief, the Trial Plaintiffs
had no evidence that they were exposed to 10 rems of
ionizing radiation and, therefore, there was no material
factual dispute in regard to causation.

The admission of Wing's lung cancer testimony would not
change that result. It is important to remember not only
that the District Court found that the "all cancer" and
"leukemia" portions of Wing's cancer incidence study were
admissible and that the court considered that testimony in
_________________________________________________________________

172. See p. 94 supra.

173. The Trial Plaintiffs' do not challenge the District Court's exclusion
of Lochbaum's testimony or its finding that his testimony would not be
sufficient to defeat the defendants' summary judgment motion. In fact,
his name is only mentioned in passing. Trial Plaintiffs Br. at 14 n.24.

                               180
its summary judgment analysis. The problem with Wing's
cancer incidence study is that Wing assumed high levels of
radiation exposure, see App. Vol. VIII, at 6871, and he
therefore attributed the elevated cancer rates to that
assumed exposure. But, as a result of the exclusionary
rulings, there was no evidence of record to support Wing's
assumption of high levels of radiation releases.
Furthermore, Wing admitted at the in limine hearing that if
the radiation levels were as postulated in the Hatch/Susser
study, then he would not be able to make a causal
connection between the accident releases and the elevated
cancer rates. Id. at 7276-77. Consequently, the District
Court ruled because the Trial Plaintiffs could not support
Wing's assumption of high levels of radiation releases, "the
Wing cancer study does nothing to assist Plaintiffs in
creating a material factual dispute or meeting their burden
of proof." 927 F. Supp. at 869. Even though we disagree
with the exclusion of Wing's lung cancer testimony, we
agree with that conclusion.

Consideration of Wing's improperly excluded lung cancer
testimony would not create a genuine issue of material fact.
If all of his cancer and leukemia testimony could not defeat
a summary judgment motion, we are at a loss to see how
a consideration of his lung cancer testimony would defeat
that motion. Wing's lung cancer testimony is based on an
assumption of high levels of radiation exposure which the
Trial Plaintiffs were not able to prove. Consequently, Wing's
lung cancer testimony would not create an issue of fact.
Although exclusion of the lung cancer testimony was an
abuse of discretion, its admission would not change the
ultimate outcome.

5. Exclusion of Experts' Submissions as Untimely.

The Trial Plaintiffs argue that the District Court
committed reversible error by refusing to consider "vast
amounts of plaintiffs' expert evidence, on the basis of
untimeliness." Trial Plaintiffs' Br. at 59. However, with the
exception of a brief discussion of the District Court's
decision not to allow Shevchenko to testify about the
results of a FISH study,174 Id. at 66, the Trial Plaintiffs have
_________________________________________________________________

174. For a discussion of the FISH methodology, see p. 131 n.127, supra.
In regard to the exclusion of Shevchenko's testimony of the FISH study,

                               181
not specifically identified what "vast amounts" of evidence
they claim the District Court refused to consider. Nor have
they attempted to explain how the court's alleged refusal
affected either the admissibility determinations or the
court's summary judgment decision.

It is clear that the District Court excluded a number of
Trial Plaintiffs' experts' filings as a sanction for counsels'
discovery violations. Apparently, the Trial Plaintiffs'
counsel's filing of untimely expert reports was a recurring
problem in this litigation.

On November 9, 1995, the District Court excluded the
testimony of a number of experts because their reports
were untimely filed. No memorandum of law explaining that
order was issued concurrently with the order. However, on
January 5,1996, the District Court filed an opinion which,
inter alia, explained the reasons for the November 9, 1995,
order. See In re TMI Litigation Cases Consolidated II, 911 F.
Supp. 775, 828 (M.D. Pa. 1996). There, the District Court
noted that its order of November 13, 1994, directed the
disclosure of Trial Plaintiffs' expert reports on dose to be
_________________________________________________________________

the district court noted:

        Neither Professor Shevchenko nor Dr. Snigiryova analyzed the TMI
       blood samples using the FISH method prior to the November 1995
       in limine hearings. Their reports indicate that they are presently
re-
       analyzing the blood samples using the FISH method, and that these
       results will validate their findings from the general cytogenetic
       analysis. This argument distorts the letter and spirit of the
Federal
       Rules of Civil Procedure beyond recognition. Final reports of
       Plaintiffs' dose experts, containing a complete statement of the
       methodologies employed and the basis for the opinions, were due
       March 1, 1995. Had Plaintiffs produced the actualfindings of a
       study using the FISH method on the TMI blood samples at the
       November in limine hearings, the court would likely have admitted
       those findings and allowed Defendants wide latitude to cross-
       examine. That Plaintiffs only recognized the importance of
       conducting the FISH analysis after the filing deadlines passed is
not
       sufficient justification for admitting such evidence one year after
the
       filing deadline and four months after the in limine hearings on
dose
       concluded.

922 F. Supp. at 1013.
182
filed by March 1, 1995. Id. According to the court, "some
eight months later and without an explanation, Plaintiffs
attempted to introduce new reports for a total of ten
experts. Moreover, the bulk of these reports were to be
delivered by previously unidentified experts." Id. Noting that
"[f]or litigation purposes, the facts of this case must at
some point become complete," the District Court felt
compelled to "draw . . . a line in the sand." Id. at 828-29.
Accordingly, it concluded that by March 1, 1995,"the
discrete body of factual evidence with respect to the issue
of dose became fixed. . . ." Id. at 829. Therefore, it held that
any attempts "to build on this body of facts" after March 1,
1995, were misplaced and, consequently, it excluded the
untimely reports. Id.

Despite the court's clear warning, and the equally
distinct line that had been drawn, Trial Plaintiffs' counsel
persisted in filing reports after deadlines had passed. We
are normally reluctant to rely on lengthy excerpts from a
District Court's opinion to facilitate our own, independent
resolution of an appeal from that court's rulings. However,
the chronology of the various case management orders and
discovery orders is crucial to a complete understanding of
the District Court's reasons for imposing the sanction of
exclusion of evidence. Accordingly, we set forth at length
the following excerpt from the District Court's opinion dated
April 2, 1996. It details the chronology and places Trial
Plaintiffs' claims in perspective.

        Defendants have objected, both in their filings and
       during the in limine hearings, to the admission of
       supplemental expert reports filed by Plaintiffs
       subsequent to the court ordered filing deadlines. For
       the most part, the court has avoided piecemeal rulings
       on this issue opting instead to make one uniform
       ruling. The issue is now ripe for disposition. A brief
       background discussion will place matters in context.

       A. Case Management History

        The timeliness issue has recurred in many settings
       within this litigation and has been particularly
       troubling to the court. Historically, the court has
       encountered significant difficulty in keeping the parties

                               183
adhered to any case management order. As a result,
there have been close to a dozen "case management
orders." 7/10/92 Proposed Schedules of Plaintiffs and
Defendants for Taking Cases to Trial; 6/15/93 Case
Management Order (setting jury selection for 7/6/94);
11/12/93 Revised Case Management Order (moving
jury selection to 10/3/94 at the request of parties);
5/13/94 Order Amending Case Management Schedule
(moving jury selection to 4/13/95); 7/28/94 Order
(granting Plaintiffs' request for further amendment of
pre-trial schedule); 10/14/94 Order (further amending
pre-trial schedule at Plaintiffs' request, and noting that
absent extreme and compelling circumstances no
further amendments will be entertained); 10/19/94
Order (directing parties to submit final joint case
management schedule in response to correspondence
from counsel); 11/3/94 Order (adopting parties'final
joint case management schedule, noting that said order
is binding and that it will not be amended absent
extreme and compelling circumstances); 5/8/95 Order
(moving jury selection to 6/3/96). Much to its own
detriment, the court has been flexible and
accommodating with respect to the pre-trial schedule.

 In November 1994, having grown weary of the
parties' inability to comply with set deadlines and
fearing that the instant action would languish, the
court ordered the parties to draft a final joint case
management schedule. On November 3 the court
adopted the schedule proposed by the parties and
again indicated that the schedule would not be altered
absent extreme and compelling circumstances. On May
8, 1995, the court issued an order supplementing the
November 1994 case management order to place the
case on the June 1996 trial list. Since the entry of the
May 8 order, the court, although permitting minor
alterations to the schedule, has denied any motion to
amend that would effectively remove the case from the
June 1996 trial list.

 The captioned action, involving approximately 2,000
Plaintiffs, was consolidated under one case number in
1988. To an extent, circumstances beyond the court's

                        184
control, such as the filing of interlocutory appeals and
Congress's amendment of the Price Anderson Act, have
stymied the prompt resolution of this action.
Nevertheless, a review of the docket reveals that the
test cases's torpid progression toward trial is due in
part to the parties' willingness to stipulate to
extensions of time and alterations of the case
management schedule and the court's historical
willingness to accommodate such requests.

B. Plaintiffs' Expert Reports

 Defendants object to the admission of all of Plaintiffs'
expert reports and supplemental affidavits filed
subsequent to the court ordered filing deadlines.
Although tedious, the following review of Plaintiffs
practice in filing expert reports is warranted.

 Pursuant to an order dated May 13, 1994, Plaintiffs
were to file the expert reports of James Gunckel,
Richard Webb and Ignaz Vergeiner not later than
August 1, 1994. This order also directed that expert
reports on medical causation were to be filed not later
than September 1, 1994 and that expert reports on
punitive damages were to be filed not later than
October 1, 1994. On August 1, 1994, Plaintiffs filed the
6/94 report of Ignaz Vergeiner ("TMI Treatise 1"), and
the 5/26/94 and 8/1/94 affidavits of Douglas
Crawford-Brown. On August 4, 1994, Plaintiffs filed the
8/1/94 preliminary report of Richard Webb entitled"A
Preview Short Synopsis." Thus, the report of James
Gunckel was not timely filed on August 1, and the
August 4 filing of the Webb "Preview" was both
untimely and in contravention of Rule 26(a)(2) of the
Federal Rules of Civil Procedure ("The report shall
contain a complete statement of all opinions to be
expressed and the basis and reasons therefor ..."). The
court was remiss in not striking these filings
immediately and, in temporarily overlooking these rule
violations, the court may have unwittingly encouraged
Plaintiffs' improper conduct. The record reflects that
these 1994 filings were only the first in a long stream
of improper and untimely filings.

                        185
 On September 15, 1994, one and one-half months
after the filing deadline, Plaintiffs filed the 7/6/94
Affidavit of Vladimir Shevchenko. On November 3,
1994, the court entered the final joint case
management schedule. This schedule extended the
deadline for Plaintiffs' filing of dose and medical
causation expert reports to March 1, 1995. On March
1, Plaintiffs filed the expert "reports" of the following
experts: Armentrout, Crawford-Brown, Gunckel,
Hinrichesen, Lochbaum, Shevchenko, Vergeiner, Webb,
Wing, Fajardo, Winters, Zakrzewski. On March 14,
without leave of court, Plaintiffs supplemented their
March 1 filing with the reports of Shevchenko, Tascaev,
Kozubov, Popov, Portman, Tarasenko, and Snigiryova.
On March 15, again without leave of court, Plaintiffs
supplemented their March 1 filing with the report of
Bruce Molholt. Finally, on March 29, without leave of
court, Plaintiffs filed a third supplement to the March
1 filing adding to the reports of Shevchenko and
Zakrzewski. Thus, as of April 1995, Plaintiffs had late-
filed a significant portion of their expert reports on
dose and medical causation.

 In February 1995, the court issued a preliminary
memorandum of law related to Defendants' motion in
limine to exclude Dr. Molholt's 4/8/93 report, and
ordered limited additional briefing with respect to
certain of the Paoli II factors. In re TMI, Mem. Op. at
22 (M.D. Pa. February 14, 1995) ("[T]he court has
invited the parties to respond concisely to the issues
raised ... this is not an invitation to deluge the court
with paper. Clear, concise, relevant information will
assist the court in reaching a just resolution; likewise,
the submission of frivolous or irrelevant information
will be frowned upon.") As exhibits to their court-
ordered filing, Plaintiffs submitted several new expert
reports (5/1/95 Molholt; 4/24/95 Kerman; 5/2/95
Kerman; 2/27/95 Crawford-Brown). In September
1995, Plaintiffs, again without leave of court, untimely
filed the reports of Theodore Sterling and Ronald
Kerman.

 The next battery of Plaintiffs' expert reports were filed

                        186
       as exhibits to their opposition to Defendants' motion in
       limine to exclude Plaintiffs' dose experts. On October
       25, Plaintiffs filed as exhibits the updated reports of
       the following experts: Vergeiner (two separate affidavits
       dated 10/18/95), Armentrout (10/10/95 Aff.;
       10/22/95 Aff.), Gunckel (8/23/95 Aff.), Shevchenko
       (10/6/95 Aff.), Wing (10/19/95 Aff.), Crawford-Brown
       (10/20/95 Aff.), Molholt (9/8/95 Aff.; 9/14/95 Aff.).
       On October 31, with leave of the court,175 Plaintiffs'
       supplemented the record with the following
       affidavits/new reports: Armentrout (9/20/95 Aff.;
       5/11/95 Aff.), Blanch (10/31/95 Aff.), Kerman
       (10/30/95 Aff.), King (10/30/95 Aff.), Reyblatt
       (10/31/95 Aff.), Shevchenko (10/6/95 Aff.), Kozubov
       (9/12/95 Aff.), Smirennyi (10/30/95 Aff.), Wing
       (10/27/95 Aff.). On January 16, 1996, as exhibits to a
       brief in opposition to Defendants' motion to compel,
       Plaintiffs filed the following supplemental affidavits:
       Crawford-Brown, Ornstein, Purcell, Reyblatt. Finally,
_________________________________________________________________

175. The district court explained that it re-opened discovery for the
following reason:

         Through a Memorandum and Order dated October 19, 1995, the
         court re-opened discovery from October 20 to October 30 for the
         purpose of granting Plaintiffs access to original plant data stored
at
         the Emaus Street repository. The court granted Plaintiffs motion to
         compel despite the fact that "[a]fter sitting on their right to
access
         these materials for nearly one decade, Plaintiffs now, one week
         before their brief on the in limine issues is due and after the
formal
         close of discovery, request that Defendants be compelled to produce
         the aforementioned documents merely because it would not be
         inordinately difficult for Defendants to do so." 10/19/95 Order at
3.
         Plaintiffs offered the court no explanation as to why they had
failed
         to view this material during the formal discovery period. Id.

          Pursuant to its granting the motion to compel, the court allowed
         Plaintiffs "to supplement their brief in opposition to Defendants'
         motion in limine." The court allowed Plaintiffs to supplement the
         record to the extent that something in the original strip chart
data
       proved helpful to their case. Plaintiffs were not granted
permission
       to supplement the record with anything beyond the scope of the
       "new" original plant data.
922 F. Supp. at 1003 n.7.

                            187
       during February 1996, Plaintiffs filed the following
       supplemental affidavits without leave of court: Wing
       (10/19/95 Aff.; 1/26/96 Aff.; 1/31/96 Aff.; 2/7/96
       Aff.), Kozubov (1/30/96 Aff.), Armentrout (2/1/96 Aff.),
       Milhollin (5/5/96 Aff.), Griffin (1/30/96 Aff.), King
       (2/16/96 Aff.).

In re TMI Litigation Cases Consolidated II, 922 F. Supp.
997, 1000-03 (M.D. Pa. 1996), (original footnotes omitted).

The District Court concluded that Trial Plaintiffs'
repeated untimely filings of experts' reports provided
adequate grounds to exclude reports filed without leave of
court subsequent to court ordered filing deadlines. Id. at
1007. Realizing, however, that the exclusion of all untimely
filed reports "would result in the effective dismissal of much
of the Plaintiffs' case" and, was, therefore,"unduly harsh"
to the Trial Plaintiffs who had nothing to do with their
counsel's disregard of court orders, the District Court
sought to seek the via media between a blanket exclusion
and its concern that Trial Plaintiffs not pay too dear a price
for the conduct of their attorneys. Id. It referred back to its
aforementioned January 5, 1996, order and opinion, and
reasoned that after publication of that order and opinion,
"there could be no question" that continuedfiling of expert
submissions without leave of court was prohibited. Id. at
1008. Accordingly, it decided to exclude all supplemental
affidavits filed after January 5, 1996. However, it allowed
all supplemental affidavits and reports filed after to March
1, 1995, but prior to January 5, 1996, whose admissibility
had not yet been ruled upon.176Id.

Federal Rule of Civil Procedure 37(b)(2)(B) authorizes the
District Court to sanction a party's failure to comply with a
discovery order by "prohibiting that party from introducing
designated matters into evidence." Although the exclusion
of evidence for violation of a discovery order is an "extreme
sanction," Dudley v. South Jersey Metal, Inc., 555 F.2d 96,
_________________________________________________________________

176. The District Court also issued an order to show cause why
monetary sanctions should not be imposed against certain of Trial
Plaintiffs' counsel. On August 7, 1996, the district court entered an
order imposing monetary sanctions against counsel. That order is the
subject of Appeal No. 96-7625, discussed infra.

                               188
99 (3d Cir. 1917), the "trial court's exclusion of testimony
for failure of counsel to adhere to a pretrial order will not
be disturbed on appeal absent a clear abuse of discretion."
Semper v. Santos, 845 F.2d 1233, 1237 (3d Cir. 1988). In
Paoli II, at 791, we recognized the continuing applicability
of Meyers v. Pennypack Woods Home Owners Ass'n, 559
F.2d 894 (3d Cir. 1997) to a Rule 37 exclusion analysis. In
Pennypack, we listed certain factors which must be
considered in evaluating whether the District Court
properly exercised its discretion. They are:

       (1) the prejudice or surprise in fact of the party against
       whom the excluded witnesses would have testified, (2)
       the ability of that party to cure the prejudice, (3) the
       extent to which waiver of the rule against calling
       unlisted witnesses would disrupt the orderly and
       efficient trial of the case or of other cases in the court,
       and (4) bad faith or willfulness in failing to comply with
       the district court's order.

559 F.2d at 904-05. The District Court applied the
Pennypack factors here and concluded that

       (1) Defendants would be prejudiced by the admission of
       certain of the untimely reports insofar as the rigorous
       pre-trial schedule precludes them from having
       sufficient time to prepare to cross-examine on the late-
       filed reports; (2) Defendants are unable to cure the
       prejudice insofar as the court is unwilling to further
       alter the pre-trial schedule because such alteration
       would necessitate postponing the trial date; (3) waiver
       of the Rule 37 sanctions would disrupt the orderly trial
       of this case as well as a multitude of other cases on the
       court's docket; and (4) Plaintiffs repeated violation of
       numerous orders of this court, failure to seek leave of
       court before filing untimely reports, and "covert" filing
       of additional reports as exhibits to a variety of
       unrelated motions rather than "overtly" making
       supplemental filings, rises to the level of bad faith.

922 F. Supp. at 1004.

We agree with the court's analysis. Accordingly, we do
not believe that the District Court abused its discretion in
imposing the sanction of exclusion under Rule 37. All of the

                               189
reports which defendants sought to exclude werefiled after
the formal close of discovery. Discovery in this litigation was
open for nearly one decade. Trial Plaintiffs' counsel can
hardly complain that they had inadequate time to provide
the desired reports, nor can they claim that the exclusion
of the late reports in response to their practice of
continually ignoring District Court deadlines caught them
by surprise. Counsel's failure to comply with the deadlines
imposed by the District Court is inexcusable. The District
Court recognized it as such, and responded appropriately.

Although it appears from the record that the defendants
knew the identity of the expert witnesses in a timely
fashion, the record also shows that the substance of the
experts' reports was not known to the defendants. Many of
the timely reports have little, if any, resemblance to the
supplemental initial reports which the Trial Plaintiffs
subsequently filed. For example, Molholt's March 13, 1995
and May 1, 1995 reports differ in a number of significant
ways from his initial April 8, 1993 report. Furthermore,
experts' submissions continued to be made up to, during,
and even after, the in limine hearings.

In Paoli II, the District Court precluded a physician from
testifying about a medical monitoring program that he
thought the plaintiffs should undergo because counsel did
not timely submit a Fed. R. Civ. P. 26(b)(4) statement
detailing the substance of the physician's testimony about
the monitoring program. We found that to be an abuse of
discretion because the failure to timely file was only a
"slight deviation from pre-trial notice requirements, and
admitting the witness was likely to cause only slight
prejudice to the defendants, who were already aware of the
basic substance of the witness' testimony." Paoli II, at 792.
However, the considerations which led us to find an abuse
of discretion in Paoli II are not present here. Here, the
District Court was faced with a pattern of filings that
constituted a flagrant violation of pre-trial orders. The
pattern was as persistent as it was unjustified. The District
Court's exclusion under Rule 37 was well within its
discretion.

6. Conclusion.

Earlier in our discussion we noted that although the Trial
Plaintiffs appeal from the District Court's grant of summary

                                190
judgment to the defendants, they do not argue that the
grant of summary judgment was improper in view of the
court's admissibility decisions on their dose experts. In
other words, they do not argue that the District Court erred
when it found that the admissible expert testimony of
Vergeiner, Shevchenko and Wing was insufficient to create
a genuine issue of material fact. Consequently, our inquiry
has focused on the propriety of the District Court's
gatekeeping role under Daubert and not on the standards
governing the grant of summary judgment. As we explained
earlier, we need to decide whether the improperly excluded
testimony created a genuine issue of material fact only if we
determined that the District Court erred in its Daubert
analyses of the proffered experts.

However, with the exception of Wing's lung cancer
testimony, we have found that the District Court's
admissibility determinations were well within its discretion
as a gatekeeper. We have also determined that the improper
exclusion of Wing's lung cancer testimony does not create
a genuine issue of material fact. Finally, we have found that
the District Court did not abuse its discretion by excluding
evidence under Fed. R. Civ. P. 37(b)(2)(B). Therefore, we will
affirm the District Court's grant of summary judgment in
favor the defendants and against the Trial Plaintiffs.

B. The Non-Trial Plaintiffs' Appeal.

As we noted in the Procedural History portion of this
opinion, the District Court held that its decision on the
defendants' summary judgment motion directed to the Trial
Plaintiffs would be binding on all plaintiffs to the extent
that the Trial Plaintiffs' ruling turns on broad evidentiary
issues common to all plaintiffs. See In re TMI Litigation
Consolidated Proceedings, 927 F. Supp. 834, 838 (M.D. Pa.
1996). Consequently, when the District Court held that the
Trial Plaintiffs could not present dose evidence sufficient to
resist summary judgment, it extended that holding to all
plaintiffs. The court held:

       Because the court finds the quantum of evidence on
       the issue of dose to be insufficient, and because no
       Plaintiff will be able to state a prima facie case without

                               191
       adequate dose evidence, the instant ruling is binding
       on all Plaintiffs.

Id. at 838.

Not unexpectedly, the Non-Trial Plaintiffs contend that
the extension of the Trial Plaintiffs' summary judgment
decision to them was improper. In support of that
contention, they make a number of arguments, viz., (1) that
their cases were consolidated for administrative purposes
only; (2) that P 3 of the Stipulation is a clear reservation of
rights that there would not be a consolidated trial that
binds all plaintiffs; (3) that the Non-Trial Plaintiffs have the
right to present different proofs, experts and theories of
recovery than those presented by the Trial Plaintiffs; (4)
that this is not a class action and they were never given the
opportunity to "opt-out" of a consolidated trial; (5) that it is
unfair to extend the discovery sanctions imposed against
the Trial Plaintiffs against them; (6) that they never agreed
that they had to demonstrate that they were exposed to 10
rems or more of radiation in order establish causation; and
(7) personal injury causation is a highly individualized
question which needs to be determined in a case-by-case
basis.

The defendants contend that the District Court's
extension of the summary judgment to the Non-Trial
Plaintiffs was correct. They argue that because of
consolidation, the case management orders governing
discovery and all pre-trial proceedings applied to all
plaintiffs, both trial and non-trial.177 They reason that
_________________________________________________________________

177. Defendants also argue that it is clear "that summary judgment can
be entered in cases consolidated for pretrial purposes, and result in the
termination of all of the consolidated cases." Appellees' Br. at 14. In
support of that proposition, they rely on our opinion in In re Donald J.
Trump Casino Sec. Litig. -- Taj Mahal Litigation , 7 F.3d 357, 367 (3d
Cir.
1993), cert. denied, 510 U.S. 1178(1994), where we held that transferred
cases consolidated for pretrial purposes under the 28 U.S.C. S 1407 can
be terminated by a transferee court under Rule 12(b)(6). However, Trump
does not apply here because S 1407 concerns multidistrict litigation and,
more importantly, the parties in all of the cases transferred under
S 1407, were before the District Court that granted the pre-trial
dispositive motions.

                               192
inasmuch as summary judgment is a pre-trial proceeding,
it therefore applied to all of the plaintiffs, and the extension
of the summary judgment decision was therefore a natural
result of the consolidation order.

However, we believe that both sides to this appeal have
failed to see some essential issues which mitigate against
the extension of the summary judgment motion to the Non-
Trial Plaintiffs. The primary inquiry should be determining
the effect of consolidation on the substantive rights of the
parties in the consolidated cases. The TMI plaintiffs' cases
were consolidated under Rule 42(a), which provides:

       When actions involving a common question of law or
       fact are pending before the court, it may order a joint
       hearing or trial of any or all the matters in issue in the
       actions; it may order all the actions consolidated; and
       it may make such orders concerning proceedings
       therein as may tend to avoid unnecessary costs or
       delay.

Fed. R. Civ. P. 42(a). The purpose of consolidation is "to
streamline and economize pretrial proceedings so as to
avoid duplication of effort, and to prevent conflicting
outcomes in cases involving similar legal and factual
issues." In re Prudential Securities Inc. Ltd. Partnerships
Litigation, 158 F.R.D. 562, 571 (S.D.N.Y. 1994).
Consolidation, however, is only a matter of "convenience
and economy in administration." Johnson v. Manhattan Ry.
Co., 289 U.S. 479, 497 (1933).178 Consolidation "does not
merge the suits into a single cause, or change the rights of
the parties, or make those who are parties in one suit
parties in another." Id.

We have not had many occasions to cite Johnson v.
Manhattan Ry. Co. in our prior opinions. In Bradgate
Associates v. Fellows, Read & Associates, Inc., 999 F.2d
745, 750 (3d Cir. 1993), we noted that although
consolidated cases are heard together, "they are not
necessarily merged forever and for all purposes." There,
commenting on Johnson, we wrote:
_________________________________________________________________

178. Consolidation in Johnson was made pursuant to 28 U.S.C. S 734, a
precursor to Fed. R. Civ. P. 42.

                               193
       Johnson cautions that while consolidated cases may be
       treated as one lawsuit in order to conserve judicial
       resources, the procedure should not impose the heavy
       toll of a diminution of any party's rights.

Id. (emphasis added). The facts in Bradgate, while
admittedly not at all like the facts here, nonetheless
demonstrate that consolidation is not intended to affect the
substantive rights of the parties to the consolidated cases.

The parties in Bradgate were Bradgate Delaware and
Bradgate New Jersey, both of which were real estate
development firms. The former was a Delaware corporation,
and the latter was a New Jersey corporation. Presumably,
both were part of Bradgate Associates. Fellows, Read was a
New Jersey engineering firm that had contracted with either
Bradgate Delaware or Bradgate New Jersey to provide
engineering services. A controversy arose and Fellows, Read
sued Bradgate Delaware in New Jersey state court to
recover payment for services rendered. Bradgate Delaware
responded by filing a federal lawsuit in New Jersey alleging
fraud, negligence and breach of contract and removing
Fellows, Read's state suit to federal court where the state
and federal cases were consolidated.

Bradgate Delaware alleged in its federal complaint and its
removal petition that diversity existed because Bradgate
Delaware was the successor in interest to Bradgate New
Jersey. The latter was the entity which Fellows, Read
claimed was the real party in interest in the engineering
services contract. Fellows, Read challenged Bradgate
Delaware's diversity allegations claiming that Bradgate New
Jersey was still a viable corporate entity and that Bradgate
Delaware had not succeeded to Bradgate New Jersey's
interests. Thus, according to Fellows, Read, diversity did
not exist, and the district court had no subject matter
jurisdiction. For reasons not relevant here, the district
court agreed that it had no diversity jurisdiction and
remanded both the original federal action and the removed
state action back to New Jersey state court. Fellows, Read
appealed the district court's decision to remand that
portion of the case which was originally filed in federal
court.

                               194
We found that a remand of both cases was error that
prejudiced Fellows, Read. We reasoned that finding an
absence of diversity terminates a case originallyfiled in
federal court. But, a finding of lack of subject matter
jurisdiction does not extinguish a removed state court case.
The state court case is simply remanded to state court.
However, the district court, "diminished Fellows, Read's
rights by prolonging litigation over claims which should
have been dismissed," by remanding both cases to state
court, instead of dismissing the federal court case and
remanding only the state court case. Id. at 751. The proper
procedure the district court should have followed was to
"apply the rules pertaining to dismissal and remand as if
the cases had retained their separate identities and had
never been consolidated." Id.

Admittedly, Bradgate and the Non-Trial Plaintiffs' appeal
here are not remotely similar. In fact, the result in Bradgate
is the exact opposite of the result here. That is, while the
court was forcing Fellows, Read to litigate a case it should
not have had to litigate, the District Court here was denying
the Non-Trial Plaintiffs the opportunity to litigate the cases
they wanted to litigate. Nevertheless the principle
underlying Bradgate, i.e., that consolidation cannot affect
the substantive rights of the parties to the consolidated
cases, is applicable to the Non-Trial Plaintiffs' consolidated
cases, and is consistent with our application of Johnson.

It is beyond dispute that the District Court's extension of
the Trial Plaintiffs' summary judgment decision to the Non-
Trial Plaintiffs' claims adversely affected the substantive
rights of the Non-Trial Plaintiffs. However, under Johnson
and Bradgate, the District Court could not properly
extinguish the substantive rights of the 1,990 Non-Trial
Plaintiffs merely because all of the cases had been
consolidated.

Upon close examination, the TMI Non-Trial Plaintiffs and
Trial Plaintiffs are even more separated than the plaintiffs
in Bradgate because the Non-Trial Plaintiffs were not even
litigating their claims and not presenting arguments to the
District Court. The TMI personal injury litigation here
involves a "test plaintiff " approach to trying a mass tort
case. However, there is nothing here to indicate that the

                               195
Non-Trial Plaintiffs were given an opportunity to object the
defendants' motion for summary judgment or otherwise
protect their substantive claims.

Moreover, Rule 42(b) states:

       The court, in furtherance of convenience or to avoid
       prejudice, or when separate trials will be conducive to
       expedition and economy, may order a separate trial of
       any claim, cross-claim, counterclaim, or third-party
       claim, or of any separate issue or of any number of
       claims, cross-claims, counterclaims, third-party claims,
       or issues, always preserving inviolate the right of trial
       by jury as declared by the Seventh Amendment to the
       Constitution or as given by a statute of the United
       States.

Fed. R. Civ. P. 42(b)(emphasis added). The extension of the
summary judgment decision to the Non-Trial Plaintiffs
implicates their Seventh Amendment jury trial rights.
Summary judgment does not violate a party's Seventh
Amendment jury trial rights so long as the person having
the right to the jury trial is an actual participant in the
summary judgment proceeding. See City of Chanute,
Kansas v. Williams Natural Gas Co., 995 F.2d 641, 657
(10th Cir. 1992) ("[S]ummary judgment, applied properly,
does not violate the Seventh Amendment.") (citing Fidelity &
Deposit Co. v. United States ex rel. Smoot, 187 U.S. 315,
319-21 (1902)). However, absent a positive manifestation of
agreement by Non-Trial Plaintiffs, we cannot conclude that
their Seventh Amendment right is not compromised by
extending a summary judgment against the Trial Plaintiffs
to the non-participating, non-trial plaintiff. In fact, a
Seventh Amendment argument was made in the District
Court, but the argument was summarily dismissed. 927 F.
Supp. at 838 n.7.

The District Court's extension of the Trial Plaintiffs'
summary judgment decision to the Non-Trial Plaintiffs
would also improperly extend the doctrine of collateral
estoppel/issue preclusion. See DeLuca v. Merrell Dow
Pharmaceuticals, Inc., 911 F.2d 941 (3d Cir. 1990). In
DeLuca, we commented on a defense theory that a group of
consolidated Bendectin cases should be dismissed because

                               196
of positive outcomes for Bendectin defendants in other
cases. We said:

       [W]e do not have the authority to create special rules to
       address the problems posed by continued Bendectin
       litigation. Principles of issue preclusion have not
       developed to the point where we may bind plaintiffs by
       the finding of previous proceedings in which they were
       not parties, even by a proceeding as thorough as the
       multidistrict common issues trial.

Id. at 952. Although DeLuca is distinguishable from the
same as the Non-Trial Plaintiffs' case, the District Court's
extension of the Trial Plaintiffs' summary judgment decision
to the nonTrial Plaintiffs' claims implicates the issue
preclusion concerns we found troublesome in DeLuca.

Finally, we believe that the District Court erred by
holding that all plaintiffs had to present evidence that they
were exposed to 10 rem or more of ionizing radiation in
order "to establish causation on the basis of a specific
radiation exposure level." 927 F. Supp. at 865. Based on its
review of the scientific literature, Id. at 834; 844-45, the
District Court found that there is a consensus in the
scientific community that, at levels of exposure below 10
rem, the causal link between exposure and cancer
induction is purely speculative. Id. at 865. Consequently,
the court held that, faced with evidence of an equivalent
exposure below 10 rem, "no rational jury . . . could find it
more likely than not that radiation induced a given
neoplasm." Id.

At exposure levels below 10 rem (100 mSv) or 10 rad (100
mGy), cancer risks are based on extrapolations from risks
seen at higher exposure levels. See RADIATION DOSE
RECONSTRUCTION, at 8 ("It is important to note that serious
health effects of exposure to ionizing radiation, such as an
increase in cancer, have not been observed directly at doses
below 0.2 Gy (20 rad) among the survivors of the atomic
bombing of Hiroshima and Nagasaki. The risks assumed to
occur at doses below 0.2 Gy (20 rad) are, therefore,
extrapolations from the risks seen at intermediate[0.2-2.0
Gy (20-200 rad)] and high [>2 Gy (>200 rad)] doses to doses
above natural background radiation."); see also MEDICAL

                               197
EFFECTS, at 69 ("Virtually all of the data used to derive risk
estimates for low-dose levels are obtained from situations in
which the exposure level actually occurred at dose levels
above 0.1 Gy (10 rad)."). However, the fact that risks of
cancer from exposure at low doses are based on
extrapolations from higher doses does not mean that the
scientific community believes that there is no causal
connection between a low-level exposure and cancer
induction. We do not believe that the scientific community
views that connection to be speculative. Rather, as noted
above, at very low doses it is possible that ionizing radiation
may deposit sufficient energy into a cell to adversely modify
it. ICRP, at 98. Indeed, scientists assume that there is no
threshold for the induction of cancer. MEDICAL EFFECTS, at
69. In other words, ionizing radiation can cause cancer
even at the lowest doses, and therefore it has to be taken
into account at all dose levels. ICRP, at 67.

The Non-Trial Plaintiffs ought to be able to attempt to
establish that doses below the threshold selected by Trial
Plaintiffs has induced their neoplasms, or caused their
pathologies. Accordingly, we conclude that it was error for
the District Court to hold that all the plaintiffs had to
demonstrate an exposure of at least 10 rem to satisfy their
burden of establishing causation. By doing so, the District
Court was, in effect, deciding, contrary to the opinions of
the scientific community, that 10 rem was the threshold for
cancer induction, and that exposure to lesser doses of
ionizing radiation could not reasonably be believed to cause
cancer.179

The District Court's finding that all plaintiffs had to
demonstrate an equivalent dose exposure of 10 rem or
more did not affect the outcome of the Trial Plaintiffs' cases
because, as noted earlier, they proceeded on the theory that
they were exposed to at least that equivalent dose of
_________________________________________________________________

179. Although, as noted in our discussion of the physics involved here,
many observations of atomic behavior lead to counter-intuitive
conclusions, we nevertheless think that common sense alone mitigates
against establishing a bright line threshold for safe irradiation. We do
not believe, for example, that a person who has been exposed to 10 rem
of radiation is at risk for developing a neoplasm, but someone exposed
to 9.99 rem is not.

                               198
ionizing radiation. The Trial Plaintiffs' medical causation
experts premised their opinions that radiation was the
cause of the test plaintiffs' neoplasms on their expectation
that the dose exposure experts would demonstrate that the
test plaintiffs were exposed to 10 rem or more of ionizing
radiation. 927 F. Supp. at 862-863. Although discovery is
closed as to all plaintiffs, we do not know anything about
the trial theories of the Non-Trial Plaintiffs. We do not know
whether they would also agree to proceed on the basis of an
equivalent exposure of at least 10 rem. Moreover, we do not
know the level of exposure the Non-Trial Plaintiffs' medical
causation experts based their opinions on.

We also note that not only is there a statistical
association between radiation and health effects, but also
that a method for determining the likelihood of radiation-
caused malignancy has been established by the National
Council on Radiation Protection and Measurements. See
NCRP 7. The Council has established a "probability of
causation (PC) approach" for determining the probability (as
opposed to absolute proof) that a particular malignancy
may have been caused by exposure to ionizing radiation.
Although the radiation dose to the individual is a variable
in the PC equation, there is no specific dose required to
make the equation workable.180

Accordingly, we hold that the District Court's extension of
the summary judgment to the Non-Trial Plaintiffs was error,
and we will reverse the grant of summary judgment to the
defendants on the Non-Trial Plaintiffs' claims and remand
for further proceedings.181
_________________________________________________________________

180. We take no position as to whether an expert opinion as to tumor
causation that is based upon the PC approach could withstand a
Daubert challenge or a challenge under Rule 703. We note the PC
approach here, however, as it demonstrates, at least one of the problems
in the District Court's decision to hold Non-Trial Plaintiffs to the 10
rem
threshold.

181. With regard to the claims of the Non-Trial Plaintiffs, we note that
over 1,600 of them are represented by the law firms of Levin, Fishbein,
Sedran & Berman, Esqs., and Hepford, Swartz & Morgan, Esqs.
However, approximately 300 of the Non-Trial Plaintiffs are represented
by The Tarasi Law Firm, P. C., and the remaining Non-Trial Plaintiffs are

                               199
C. The Monetary Sanctions Appeal.

Trial Plaintiffs' counsel, Arnold Levin, Laurence Berman
and Lee Swartz, appeal from the District Court's imposition
of monetary sanctions against them in the amount of $500
each for violations of the mandatory disclosure
requirements of Fed. R. Civ. P. 26(a) and for disregard of
court orders issued pursuant to Fed. R. Civ. P. 26(f). This
appeal closely overlaps the Trial Plaintiffs' assertion that
the District Court's exclusion of evidence under Fed. R. Civ.
_________________________________________________________________

represented either by Shawn A. Bozarth, Esq., or Peter J. Neeson, Esq.
On August 5, 1996, a Notice of Appeal was filed in the district court on
behalf of all the plaintiffs, including the Non-Trial Plaintiffs. On
October
31, 1996, Entries of Appearance were filed with the Clerk of Court by
Levin, Fishbein, Sedran & Berman and Hepford, Swartz & Morgan on
behalf of the appellants they represent, all of whom were specifically
identified in the Entry of Appearance. On November 22, 1996, Lou
Tarasi, Esq., of The Tarasi Law Firm, P. C., filed his Entry of Appearance
on behalf of the appellants he represents, but no specific appellant was
identified. No Entry of Appearance was filed by Shawn A. Bozarth, Esq.,
on behalf of his clients, or by Peter J. Neeson, Esq., on behalf of his
clients.

A brief on behalf of the appellants represented by Levin, et al., and by
Hepford, et al., was timely filed. However, no brief was filed on behalf
of
the appellants represented by The Tarasi Law Firm. Mr. Tarasi appears
only on the Brief of the Levin and Hepford appellants as "Of Counsel for
the Appellants Identified in the Entry of Appearance." No briefs were ever
filed by Messrs. Bozarth and Neeson and their names do not appear on
the brief filed by Levin, et al., and Hepford, et al.

The appellees filed a motion, under Fed. R. App. P. 31(c) and Third
Circuit LAR 107.2(b), to dismiss the appeals of the appellants
represented by Tarasi, Bozarth and Neeson based on their failure to file
briefs. Mr. Tarasi responded by filing a motion to join in the brief filed
by Levin and Hepford. Messrs. Bozarth and Neeson did not respond to
appellees' motion to dismiss. On April 15, 1997, order was entered
granting Tarasi's motion to join in the Levin and Hepford brief. However,
the appellees' motion to dismiss was referred to the merits panel for
disposition.

The April 15, 1997 order moots the motion to dismiss the appeal as to
the Tarasi appellants. However, because Messrs. Bozarth and Neeson did
not file briefs or in any way respond to the appellees' motion to dismiss,
we will dismiss the appeals as to the appellants represented by them.

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P. 37 was an abuse of discretion. As noted above, the
District Court filed a well-reasoned and comprehensive
Memorandum Opinion, dated August 7, 1996, explaining
its rationale for the imposition of monetary sanctions
against counsel. We can add nothing to that analysis. For
the reasons we have already cited in our affirmance of the
District Court's exclusion of evidence, we also hold that the
District Court did not abuse its discretion by imposing
monetary sanctions against counsel and we will affirm
substantially for the reasons set forth in the District
Court's August 7, 1996 Memorandum Opinion.182

D. Reassignment Upon Remand.

One matter remains. Plaintiffs' counsel seek
reassignment of this case from Judge Rambo to another
judge upon remand. They argue that the history of this
case reflects "sharp exchanges between counsel and court"
and "hostile rebukes of counsel by the court." Sanction's
Br. at 44. However, as grounds for the requested
reassignment, they assert:

       But, plaintiffs are not relying on such conduct in
       seeking reassignment. Rather, plaintiffs' contention is
       that the TMI district court's rulings show such a strong
       and unjustified displeasure with plaintiffs' counsel and
       disbelief in plaintiffs' experts and the case that a
       reasonable person, knowing all of the facts regarding
       the district court's ruling, may well conclude that the
       judge is not impartial and cannot make objective
       rulings with respect to plaintiffs' case.

Id. This is counsel's second attempt to do an end run
around Judge Rambo. In a petition for a writ of mandamus
seeking reassignment which trial-plaintiffs' counselfiled
after the District Court's in limine rulings, counsel alleged,
inter alia, that Judge Rambo conducted "herself so as to
create `an appearance of a lack of impartiality that
jeopardizes the credibility of her evidentiary and procedural
rulings.' " See Dolan v. General Public Utilities, No. 96-7264,
_________________________________________________________________

182. We review the imposition of discovery sanctions for an abuse of
discretion. Paoli II, at 750.

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slip. op. at 3 (3d Cir. May 10, 1996). In our decision
denying the writ we stated:

       The Supreme Court has made clear that "judicial
       rulings alone almost never constitute valid basis for a
       bias or impartiality motion. Liteky v. United States, 114
       S. Ct. 1147, 1157 (1994). Thus, we have held
       "disagreement with a judge's determinations and
       rulings cannot be equated with the showing required to
       so reflect on impartiality as to require recusal. Jones v.
       Pittsburgh Nat'l Corp., 899 F.2d 1350, 1356 (3d Cir.
       1990). Petitioners' allegations amount to little more
       that disagreement with her legal rulings.
       Disqualification is not an appropriate remedy for
       disagreement over a legal ruling. In the event the
       court's evidentiary rulings may be in error, they are
       subject to review on appeal.

        Petitioners also assert Judge Rambo should be
       disqualified because she allegedly made remarks to
       counsel that demonstrate personal bias. But "opinions
       formed by the judge on the basis of facts introduced or
       events occurring in the proceedings, do not constitute
       a basis for a bias or partiality motion unless they
       display a deep-seated favoritism or antagonism that
       would make fair judgment impossible." Liteky , 114 S.
       CT. at 1157. After an extensive review of the record we
       find no evidence of "deep-seated favoritism" in the
       remarks made by Judge Rambo.

Id. at 7.

In spite of this explanation of our reasons for denying
counsel's initial attempt to get their case before a different
judge, counsel reiterate the same arguments that we
previously rejected in support of the instant appeal. A
meritless legal position does not become meritorious merely
by repeating it in a subsequent appeal. Plaintiffs' counsel
have ignored our opinion in Dolan. In Dolan, we specifically
stated that disqualification is not a "remedy" to an adverse
judicial ruling. Trial counsel's arguments regarding
assignment of a new judge have not changed since Dolan,
but neither has the law. Counsel are really complaining
about the substance of Judge Rambo's rulings against

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them. However, as we informed them in Dolan, adverse
rulings do not warrant disqualification.183

For the above reasons, we will affirm the district court's
imposition of monetary sanctions and deny the request for
reassignment.

VII. CONCLUSION

To restate our decision in each appeal, we will affirm the
District Court's grant of summary judgment in favor of the
defendants on the Trial Plaintiffs' claims and will affirm the
District Court's imposition of monetary sanctions against
certain of Trial Plaintiffs' counsel. We will reverse the grant
of summary judgment in favor of the defendants on the
Non-Trial Plaintiffs' claims and remand for further
proceedings, excepting the grant of summary judgment to
defendants on the claims of the Non-Trial Plaintiffs
represented by Shawn A. Bozarth, Esq., and Peter J.
Neeson, Esq. See n.181, supra. We will dismiss the appeals
of those particular appellants for failure to file briefs. See
Matute v. Procoast Nav. Ltd., 928 F.2d 627, 630-31 & n.1
(3d Cir.), cert. denied, 502 U. S. 919 (1991), overruled on
other grounds, Neely v. Club Med Management Services,
Inc., 63 F.3d 166, 177-78 (3d Cir. 1995). Finally, we will
deny the request for reassignment.
_________________________________________________________________

183. Moreover, we can not help but comment on the commendable
manner in which Judge Rambo has handled this exceedingly difficult,
intricate and complex litigation. She has done so in a manner that
reflects patience, fairness, and a desire to let both sides be heard. For
example, as noted earlier, she allowed plaintiffs to present a portion of
Wing's testimony even though she believed it to be marginally
admissible. She allowed reports to be submitted after her January 5,
1996 order even though that order warned counsel about ignoring
deadlines.

This is not to say that this litigation has proceeded without shortened
tempers, strained patience, heated exchanges, or legal error. Such is
often encountered in litigation of this magnitude, importance and
complexity. However, it appears to us that Judge Rambo has continued
to preside over this litigation as fairly as is humanly possible, and in a
manner that is remarkably free of legal error.

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A True Copy:
Teste:

       Clerk of the United States Court of Appeals
       for the Third Circuit

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