                         UNPUBLISHED

UNITED STATES COURT OF APPEALS
                FOR THE FOURTH CIRCUIT


CHRISTOPHER J. NEWMAN; MARY             
FRANCES NEWMAN,
               Plaintiffs-Appellants,
                 v.
MOTOROLA, INCORPORATED; BELL
ATLANTIC MOBILE, INCORPORATED,
a/k/a Bell Atlantic NYNEX, a/k/a
Nynex, formerly known as Bell
Atlantic NYNEX Mobile,
Incorporated; SOUTHWESTERN BELL
MOBILE SYSTEMS, INCORPORATED,
d/b/a Cellular One,
Washington/Baltimore, a/k/a
Cellular One, a/k/a Cellular One
Washington/Baltimore;
WASHINGTON/BALTIMORE CELLULAR              No. 02-2424
LIMITED PARTNERSHIP; CELLULAR
TELECOMMUNICATION INDUSTRY
ASSOCIATION; TELECOMMUNICATION
INDUSTRY ASSOCIATION, a/k/a TIA,
               Defendants-Appellees,
                and
ABC CORPORATION, a presently
unidentified entity or entities;
CELLCO PARTNERSHIP, d/b/a Verizon
Wireless, formerly known as Bell
Atlantic Mobile, formerly known as
Bell Atlantic NYNEX Mobile;
NATIONWIDE MOTOR SALES
CORPORATION, d/b/a Nationwide
                                        
2                    NEWMAN v. MOTOROLA, INC.


Mobile Communications; CELLULAR         
ONE GROUP, a/k/a Cellular One;
JOHN DOE, a presently unidentified
individual or individuals; VERIZON
MARYLAND, INCORPORATED, a/k/a
Verizon Wireless, Verizon, formerly     
known as Bell Atlantic, Maryland,
Incorporated; SBC COMMUNICATIONS,
INCORPORATED; BELL ATLANTIC
CORPORATION, a/k/a Bell Atlantic,
                          Defendants.
                                        
           Appeal from the United States District Court
            for the District of Maryland, at Baltimore.
                Catherine C. Blake, District Judge.
                        (CA-00-2609-CCB)

                   Argued: September 26, 2003

                    Decided: October 22, 2003

    Before WIDENER, MICHAEL, and SHEDD, Circuit Judges.



Affirmed by unpublished per curiam opinion.


                            COUNSEL

ARGUED: H. Russell Smouse, LAW OFFICES OF PETER G.
ANGELOS, P.C., Baltimore, Maryland, for Appellants. Jane F.
Thorpe, ALSTON & BIRD, L.L.P., Atlanta, Georgia, for Appellees.
ON BRIEF: John C.M. Angelos, LAW OFFICES OF PETER G.
ANGELOS, P.C., Baltimore, Maryland; H. Thomas Howell, HOW-
ELL & GATELY, Baltimore, Maryland, for Appellants. Scott A.
Elder, ALSTON & BIRD, L.L.P., Atlanta, Georgia; David R. Vender-
                      NEWMAN v. MOTOROLA, INC.                        3
bush, ALSTON & BIRD, L.L.P., New York, New York; Garrett B.
Johnson, Barry E. Fields, Carole A. Cheney, Terrence J. Dee, Jona-
than E. Hinkemeyer, KIRKLAND & ELLIS, Chicago, Illinois; Paul
F. Strain, VENABLE, BAETJER & HOWARD, L.L.P., Baltimore,
Maryland; M. King Hill, III, VENABLE, BAETJER & HOWARD,
L.L.P., Towson, Maryland; Thomas C. Watson, Curtis S. Renner,
WATSON & RENNER, Washington, D.C.; Michael Esher Yaggy,
Kenneth L. Thompson, Jeffrey M. Yeatman, PIPER RUDNICK,
L.L.P., Baltimore, Maryland; Robert B. Green, David B. Irwin,
IRWIN, GREEN, DEXTER & MURTHA, L.L.P., Towson, Mary-
land; Daniel R. Lanier, MILES & STOCKBRIDGE, P.C., Baltimore,
Maryland; Paul H. Vishny, Paul E. Freehling, D’ANCONA &
PFLAUM, L.L.C., Chicago, Illinois, for Appellees.



Unpublished opinions are not binding precedent in this circuit. See
Local Rule 36(c).


                              OPINION

PER CURIAM:

   This is a product liability case, and the issue on appeal is whether
the district court erred in excluding the causation opinion proffered by
one of the plaintiffs’ experts, an epidemiologist. Finding no error, we
affirm.

   Dr. Christopher J. Newman used a cellular telephone manufactured
by Motorola, Inc. from October 1992 until he was diagnosed with
brain cancer in March 1998. During that time Dr. Newman spoke on
the telephone for approximately 343 hours, typically holding the
phone next to his right ear with the antenna retracted. Cellular phones
emit radiofrequency radiation, the exposure to which is measured by
specific absorption rate (SAR). The Federal Communications Com-
mission has promulgated regulations specifying a maximum SAR for
cellular phones, and government and private researchers have for
years studied the health effects of exposure to radiofrequency radia-
4                     NEWMAN v. MOTOROLA, INC.
tion from the use of cellular phones. These researchers have generally
failed to establish a connection between brain cancer and the use of
cellular phones. Nevertheless, Dr. Newman claimed that his use of a
cellular phone, and specifically his exposure to radiofrequency radia-
tion, caused his malignant brain tumor.

   Dr. Newman and his wife sued Motorola and other defendants on
August 28, 2000. The parties conducted discovery and designated
experts on the issues of general and specific causation. At the conclu-
sion of discovery, each side filed a motion to exclude the other’s prof-
fered expert testimony. The district court conducted an evidentiary
hearing from February 25 to March 1, 2002, after which it concluded
that the Newmans had not proffered any reliable or relevant evidence
to support either general or specific causation. The court therefore
granted the defendants’ motion to exclude the testimony of all of the
Newmans’ experts on causation. Because this ruling left the New-
mans with no admissible evidence on causation, the district court then
granted summary judgment to the defendants.

   The Newmans appeal the district court’s exclusion of only one of
their experts, Dr. Lennart Hardell (an epidemiologist), claiming that
the court improperly applied the Daubert reliability test with respect
to Dr. Hardell’s testimony. Specifically, the Newmans argue that the
district court scrutinized Dr. Hardell’s conclusions rather than his
methods and weighed evidence and assessed the credibility of com-
peting experts, which improperly transformed the Daubert hearing
into a trial on the merits. We review the district court’s exclusion of
expert testimony for abuse of discretion. Cooper v. Smith & Nephew,
Inc., 259 F.3d 194, 200 (4th Cir. 2001).

   Federal Rule of Evidence 702 requires a trial judge to perform a
gatekeeping function with respect to expert testimony; for such testi-
mony to be admissible, the judge must determine that it is both reli-
able and relevant. Fed. R. Evid. 702; Daubert v. Merrell Dow
Pharmaceuticals, Inc., 509 U.S. 579, 592 (1993). The Supreme Court
in Daubert set forth a non-exclusive checklist of factors that a judge
may consider in assessing the reliability of expert testimony. Daubert,
509 U.S. at 594. In the end, the trial judge has "considerable leeway"
in making the admissibility determination. United States v. Barnette,
211 F.3d 803, 816 (4th Cir. 2000).
                      NEWMAN v. MOTOROLA, INC.                        5
   The district court identified several problems with Dr. Hardell’s
proffered testimony on causation, and we mention two. Most signifi-
cantly, the district court observed that Dr. Hardell’s research fails to
show that users of cellular phones face an increased risk for develop-
ing malignant brain tumors. Although Dr. Hardell testified that his
research shows an increased risk for developing brain tumors gener-
ally, he achieved this result only by considering the occurrence of a
particular subtype of benign tumors, specifically, benign acoustic
neurinomas. The district court questioned the relevance of research
linking the use of cellular phones to the development of acoustic
neurinomas because Dr. Newman does not have an acoustic
neurinoma; he has a malignant astrocytoma. The district court also
questioned the reliability of Dr. Hardell’s research because it failed
to demonstrate a dose-response relationship, that is, it failed to show
that with greater use of cellular phones, a person faced a greater risk
of developing a tumor. Showing a dose-response relationship is, as
Dr. Hardell agreed, an important factor in establishing causation. In
short, Dr. Hardell’s testimony faced problems of both relevance and
reliability, as the district court determined.

   After reviewing the briefs and the joint appendix and considering
the arguments of counsel, we conclude that the district court did not
abuse its discretion in excluding the testimony of Dr. Hardell. We
affirm on the reasoning of the district court. See Newman v. Motorola,
Inc., 218 F. Supp. 2d 769 (D. Md. 2002).

                                                           AFFIRMED
