J-S39014-17

                           2018 PA Super 174


 RICHARD THOMAS WALSH,           :        IN THE SUPERIOR COURT OF
 EXECUTOR OF THE ESTATE OF       :             PENNSYLVANIA
 THOMAS J. WALSH, DECEASED       :
                                 :
                  Appellant      :
                                 :
                                 :
            v.                   :
                                 :        No. 1661 WDA 2016
                                 :
 BASF CORPORATION; BAYER         :
 CORPORATION D/B/A BAYER         :
 CROPSCIENCE, L.P., AND BAYER    :
 CROPSCIENCE HOLDING, INC.,      :
 AND/OR BAYER CROPSCIENCE, L.P. :
 AND BAYER CROPSCIENCE           :
 HOLDING, INC., IN THEIR OWN     :
 RIGHT; BIOSAFE SYSTEMS, L.L.C.; :
 CHEMTURA CORPORATION; CLEARY :
 CHEMICAL CORP.; DOW             :
 AGROSCIENCES, L.L.C.; E.H.      :
 GRIFFITH, INC.; E.I. DU PONT DE :
 NEMOURS AND CO., INC.; G.B.     :
 BIOSCIENCES CORPORATION;        :
 JOHN DEERE LANDSCAPING, INC.,   :
 SUCCESSOR TO LESCO, INC.;       :
 MONSANTO COMPANY; NUFARM        :
 AMERICAS, INC.; REGAL CHEMICAL :
 CO.; SCOTTS-SIERRA CROP         :
 PROTECTION CO.; AND SYNGENTA    :
 CROP PROTECTION, INC.           :

             Appeal from the Order Entered October 14, 2016
    In the Court of Common Pleas of Allegheny County Civil Division at
                       No(s): G.D. No. 10-018588


BEFORE:   BENDER, P.J.E., BOWES, J., and STRASSBURGER*, J.

OPINION BY BOWES, J.:                              FILED JUNE 20, 2018

     Richard Thomas Walsh, Executor of the Estate of Thomas J. Walsh,

Deceased, appeals from the October 14, 2016 order granting summary

____________________________________
* Retired Senior Judge assigned to the Superior Court.
J-S39014-17



judgment in favor of Appellees, and challenges the propriety of the trial court’s

order barring his experts from testifying pursuant to the standard enunciated

in Frye v. United States, 293 F. 1013 (D.C. Cir. 1923). Since we conclude

that the learned trial court erred in the manner in which it conducted the Frye

inquiry herein, we reverse the grant of summary judgment, vacate the order

precluding Mr. Walsh’s experts from testifying, and remand for further

proceedings.1

       The record reveals the following. The Decedent, Thomas J. Walsh, was

employed for almost forty years as a groundskeeper and golf course

superintendent at several golf courses in the Pittsburgh area.       During his

employment, he frequently and regularly applied insecticides and fungicides

(collectively “pesticides”) on the golf courses. He kept a diary of the chemicals

used on the courses and the dates of their applications. His friend and co-

worker, Blaise Santoriello, offered specific details about how the two men

applied the pesticides, what pesticides were used, in what concentrations, and

the protective gear worn. Most of the applications occurred from May through

September.

       Early on, according to Mr. Santoriello, Mr. Walsh came into physical

contact with pesticides while holding the hose spraying pesticides.       Gloves

were the only protective gear used. Later, the men wore masks and rubber

boots and overalls that they would re-wear without laundering. He recounted
____________________________________________


1 We grant Monsanto Company’s motion to withdraw the appearance of Daniel
R. Blakey, Esquire, filed on June 15, 2017.

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J-S39014-17



an instance in the mid-1980s when Mr. Walsh experienced an adverse reaction

to a product. That prompted a change to disposable protective gear. Yet, Mr.

Santoriello explained that, even then, they would be exposed to the dust from

the products while opening the bags, mixing the chemicals, and holding the

hoses.

      On October 5, 2008, Mr. Walsh presented to the emergency room

complaining of fever, chills, and a cough.     Three days later, after a bone

marrow biopsy, he was diagnosed with Acute Myelogenous Leukemia (“AML”).

Subsequent cytogenetic testing at West Penn Hospital showed chromosomal

aberrations consistent with secondary leukemias, which are linked to

radiation, chemotherapy, or chemical exposure.

      Mr. Walsh died on February 2, 2009.       His treating oncologist, James

Rossetti, D.O., later opined that Mr. Walsh’s extensive chemical exposure,

together with “the high-risk karyotype and dyspoietic features associated with

[AML] raise a high degree of suspicion that such [occupational pesticide]

exposure played a significant role in the development of his disease.” Letter

Report of James M. Rossetti, D.O., 7/19/12, at 4.

      Executor commenced this wrongful death and survival action against the

manufacturers of various pesticides that Decedent applied over the forty-year

period, asserting claims in strict products liability, negligence, and breach of

warranty. Summary judgment was granted in favor of the manufacturers and

sellers of more than twenty-five of the allegedly defective pesticides on

December 11, 2012, based on a lack of expert testimony identifying these

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pesticides as substantial contributing factors in Mr. Walsh’s death.    Fifteen

products remained in the lawsuit when the rulings that are the subject of this

appeal were made.2

       On August 5, 2013, the Bayer Defendants filed a motion to exclude

Executor’s experts, epidemiologist April Zambelli-Weiner, Ph.D., and physician

Nachman Brautbar, M.D., pursuant to Frye v. United States, 293 F. 1013

(D.C. Cir. 1923). The other remaining defendants either joined Bayer’s Frye

motion or filed their own. The substance of the Frye motions was that this

case involved novel science, and the methodologies used by these experts

were not generally accepted or conventionally applied in the relevant scientific

communities.

       The trial court ordered the parties to conduct depositions on the Frye

issue. Thereafter, the parties briefed and argued the issues. On October 5,

2016, the trial court granted the Defendants’ Frye motions and precluded the

testimony of Executor’s experts. Since Executor could not prove the requisite

causation without the expert testimony, the parties stipulated to the entry of

the October 14, 2016 order granting summary judgment, preserving all rights

to appeal the Frye determination.




____________________________________________


2  The remaining Defendants are BASF Corp.; Dow Agrosciences, LLC; John
Deere Landscaping, Inc. (successor to Lesco, Inc.); Monsanto Company;
Syngenta Crop Protection, Inc.; and the Bayer Defendants (Bayer Corp. d/b/a
Bayer Cropscience, L.P., Bayer Cropscience Holding, Inc., Bayer Cropscience,
L.P., Bayer Cropscience Holding, Inc., in their own right.

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      Executor filed the within appeal on November 3, 2016, and timely

complied with the court’s order to file a Pa.R.A.P. 1925(b) concise statement

of errors complained of on appeal.    The trial court issued a supplemental

memorandum. Executor presents one issue for our review: “Did the Plaintiff’s

experts employ generally accepted scientific methodology in arriving at their

opinions concerning medical causation in this toxic tort claim?” Appellant’s

brief at 4.

      Although the appeal herein lies from the entry of summary judgment,

the appropriate appellate standard of review is the one pertaining to the

underlying ruling that Appellant is challenging. See K.H. v. J.R., 826 A.2d

863, 870-71 (Pa. 2003). Since the correctness of the Frye evidentiary ruling

is at issue herein, the abuse of discretion standard applies. Betz v. Pneumo

Abex LLC, 44 A.3d 27, 54 (Pa. 2012). “[A]n abuse of discretion may not be

found merely because an appellate court might have reached a different

conclusion, but requires a result of manifest unreasonableness, or partiality,

prejudice, bias, or ill-will, or such lack of support so as to be clearly

erroneous.” Id. at 45.

      At issue in the underlying litigation is whether Decedent’s forty-year

occupational exposure to Defendants’ insecticides and fungicides, collectively

pesticides, some of which contain known carcinogens and teratogens, was a

substantial contributing factor in his death due to AML.    The precise issue

before us involves the propriety of the trial court’s ruling that Frye barred

Executor’s experts from testifying as to causation.

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      The Frye standard originally was intended to prevent the situation in

which a party would seek to introduce scientific evidence that was so new that

it would be impossible to “produce rebuttal experts, equally conversant with

the mechanics and methods of a particular technique.”       United States v.

Addison, 498 F.2d 741, 744 (D.C. App. 1974). Frye contemplated a judicial

inquiry, informed by experts, into the general acceptance of the scientific

methods used.     The standard required that “the thing from which the

[expert’s] deduction is made must be sufficiently established to have gained

general acceptance in the particular field in which it belongs.” Frye, supra

at 1014.   At issue in Frye was admissibility of the systolic blood pressure

deception test, commonly known as the lie detector test.       The trial court

excluded the evidence, and the court affirmed that ruling on appeal,

explaining:

      Just when a scientific principle or discovery crosses the line
      between the experimental and demonstrable stages is difficult to
      define. Somewhere in this twilight zone the evidential force of the
      principle must be recognized, and while courts will go a long way
      in admitting expert testimony deduced from a well-recognized
      scientific principle or discovery, the thing from which the
      deduction is made must be sufficiently established to have gained
      general acceptance in the particular field in which it belongs.

Frye, supra at 1014.         Pennsylvania adopted the Frye standard in

Commonwealth v. Topa, 369 A.2d 1277 (Pa. 1977), a case involving the

propriety of the trial court’s admission of voice print identification evidence

through an expert, Lieutenant Nash, of the Michigan State Police. Our High

Court, applying Frye, reasoned that

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J-S39014-17


      [t]he requirement of general acceptance in the scientific
      community assures that those most qualified to assess the general
      validity of a scientific method will have the determinative voice.
      Additionally, the Frye test protects prosecution and defense alike
      by assuring that a minimal reserve of experts exists who can
      critically examine the validity of a scientific determination in a
      particular case. Since scientific proof may in some instances
      assume a posture of mystic infallibility in the eyes of a jury of
      laymen, the ability to produce rebuttal experts, equally conversant
      with the mechanics and methods of a particular technique, may
      prove to be essential.

Topa, supra at 1282 (quoting Addison, supra at 744). The Topa Court

went on to conclude that the testimony of one expert could not satisfy this

standard,   citing   commentaries    questioning   the   reliability   of   sound

spectrographs and voiceprints and demonstrating that it was not generally

accepted within the field of acoustical science.

      Thus, the Frye standard originally was intended to prevent a party from

introducing scientific evidence that was so new that it would be impossible to

“produce rebuttal experts, equally conversant with the mechanics and

methods of a particular technique.” Addison, supra at 744. 498 F.2d 741,

744 (D.C. App. 1974).     Frye contemplated a judicial inquiry, informed by

experts, into the general acceptance of the scientific methods used.

      In the years since the adoption of the Frye standard, this Court has

clarified that “Frye only applies to determine if the relevant scientific

community has generally accepted the principles and methodology the

scientist employs, not the conclusions the scientist reaches.” Trach v. Fellin,




                                     -7-
J-S39014-17


817 A.2d 1102, 1112 (Pa.Super. 2003) (en banc). The Frye test has been

incorporated into Pennsylvania Rule of Evidence 702, which provides:

            A witness who is qualified as an expert by knowledge, skill,
      experience, training, or education may testify in the form of an
      opinion or otherwise if:

      (a)   The expert’s scientific, technical, or other specialized
            knowledge is beyond that possessed by the average
            layperson;

      (b)   The expert’s scientific, technical, or other specialized
            knowledge will help the trier of fact to understand the
            evidence or to determine a fact in issue;

      (c)   The expert’s methodology is generally accepted in the
            relevant field.

Pa.R.E. 702 (emphasis added).

      Executor contends first that a Frye inquiry was not indicated on two

grounds: 1) the causal link between pesticides and leukemia is not novel

science; and 2) it is inapplicable where a medical expert reviews medical

records and arrives at conclusions regarding the source of injuries.        See

Cummins v. Rosa, 846 A.2d 148 (Pa. 2004), Trach, supra, and Tucker v.

Community Medical Center, 833 A.2d 217, 224 (Pa.Super. 2003).

      In anticipation that we might conclude otherwise, Executor argues in the

alternative that his experts satisfied Frye’s generally-accepted-methodology

requirement for the admissibility of novel scientific evidence. His experts, Drs.

Brautbar and Zambelli-Weiner, applied the generally accepted Bradford Hill

viewpoints for establishing general causation.      Dr. Brautbar also applied




                                      -8-
J-S39014-17



differential diagnosis, a generally accepted methodology, in arriving at his

specific causation opinions.

      Executor alleges further that the trial court violated Pa.R.C.P. 207.1 and

Grady v. Frito Lay, 839 A.2d 1038 (Pa. 2003), by looking at the experts’

conclusions rather than the general acceptability of their methodologies within

the relevant scientific communities. He maintains that the court found the

experts’ methodologies unreliable simply because the experts’ conclusions did

not match those of the study authors cited. In arriving at its conclusions,

Executor contends that the trial court “delved into an area beyond the training

and experience of judges and lawyers, and substituted its analysis of the

scientific literature for the analysis that was conducted by [Executor’s]

experts.” Appellant’s brief at 17. In doing so, according to Executor, the court

improperly focused on the conclusions reached, rather than on whether the

principles and methodology were generally accepted. In addition, the court

improperly demanded indisputable evidence of the link between pesticide

exposure and AML.

      We find considerable support for Executor’s position that the link

between pesticides and cancer has crossed the threshold from novel to general

acceptance. The record reveals that more than 700 articles and studies have

been published examining the connection. See Betz v. Pneumo Abex LLC,

44 A.3d 27 (Pa. 2012) (noting link between asbestos and mesothelioma not

novel science as studies went back to 1935).        However, the Betz Court

recently clarified that a “reasonably broad meaning should be ascribed to the

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J-S39014-17



term ‘novel,’” and expanded Frye to require a hearing when a trial judge has

“articulable grounds to believe that an expert has not applied accepted

scientific methodology in a conventional fashion in reaching his conclusions.”

Id. at 545. Since the defense offered expert opinion that neither Dr. Brautbar

nor Dr. Zambelli-Weiner applied the Bradford-Hill method in a generally

accepted manner in reaching their conclusions, we find no abuse of discretion

on the part of the trial court in conducting a Frye inquiry herein.

      Nonetheless, we find merit in Executor’s contention that the Frye

inquiry herein was overly expansive. The court viewed its role as that of a

gatekeeper, charged with “review[ing] the studies that Dr. Brautbar relies

upon to determine whether they support Dr. Brautbar’s reliance[,]” and “to

make sure that the articles stood for what Dr. Brautbar said that they did.”

Supplemental Memorandum, 12/27/16, at 5. That is not the proper role of

the trial court in a Frye inquiry.

      Frye    requires   that   a    proponent   of   novel   scientific   testimony

demonstrate that the expert relied upon and conventionally applied a scientific

method generally accepted in the relevant scientific community.             Both Dr.

Brautbar and Dr. Zambelli-Weiner used the Bradford Hill criteria, which the

defense agreed was a generally accepted scientific methodology for

determining general causation. In fact, defense expert David H. Garabrant,

M.D., used the same method. See Expert report of David H. Garabrant, M.D.,

at 7 (“My opinions regarding the causal relationship between exposure to

pesticides and risk of AML are based on the causal considerations laid out by

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J-S39014-17



Austin Bradford Hill”). Even the trial court approved of Dr. Brautbar and Dr.

Zambelli-Weiner’s use of the Bradford Hill criteria.        Supplemental Opinion,

12/27/16, at 5. The method identifies nine non-exclusive criteria relevant to

such a determination, one of which is the experimental data.3 Dr. Brautbar

explained how he analyzed those nine factors in arriving at his general

causation opinions. Although the defense experts maintained that Executor’s

experts did not correctly apply the Bradford Hill criteria, they offered little or

no insight as to why the approach was unconventional. They largely disagreed

with the weight the experts assigned to various factors and the conclusions

reached, neither of which would preclude the experts from testifying.

       The trial court did not expressly find that Dr. Brautbar’s manner of

applying Bradford Hill was not generally accepted. Rather, the court focused

on Dr. Brautbar’s reference to studies in applying those factors, and concluded

that his reliance upon particular studies was not in accordance with generally

accepted scientific methodology.          In arriving at that conclusion, the court

scrutinized the studies cited by Dr. Brautbar, assessed their scientific

relevance and validity, and then arrived at its own conclusion whether the

expert’s reliance upon them was scientifically acceptable. The court’s finding

that Dr. Brautbar did not follow accepted methodologies in relying upon

certain studies in forming his opinions as to general causation added another
____________________________________________


3  The Bradford Hill factors include the consistency, strength, specificity, and
temporal relationship of the observed association; the biological plausibility of
the exposure-response relationship, as well as the biological plausibility as
viewed from data; coherence; experimental evidence; and analogy.

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J-S39014-17



layer to the generally accepted methodology requirement. Furthermore, the

trial court did not identify the methodology it was employing or reference

testimony from scientists in the field. In short, the trial court baldly concluded,

“Dr. Brautbar’s reliance on this literature to support his general causation

theory is not in accordance with generally acceptable scientific methodology.”4

Trial Court Opinion, 10/5/16, at 6.

       The trial court employed the same flawed approach in evaluating the

sources reviewed and cited by Dr. Brautbar in support of his specific causation

opinions. Notably, the defense experts did not dispute the general acceptance

of Dr. Brautbar’s choice of the differential etiology methodology 5 for

determining specific causation.         That method permits a medical expert to

render specific causation opinions based on the scientific information

available, the patient’s history, his education, training, and experience. We

routinely require our experts, especially medical experts, to apply their

scientific knowledge, information, and expertise to a unique set of

____________________________________________


4 Dr. Brautbar also referred to the Material Safety Data Sheets (“MSDSs”),
documents containing information on the potential hazards of the individual
products, in arriving at his general causation opinions.

5 Dr. Brautbar explained that, in this case, the differential etiology method
involved “ruling in all identifiable causes of (and risk factors for) acute
myelogenous leukemia and then ruling out those for which there is inadequate
evidence.” Dr. Brautbar Expert Report,    at 61. He found Decedent’s medical
history to be negative for congenital disorders, hematologic disorders,
exposure to chemotherapy, radiation, or cigarette smoking, and ruled out
substantial exposure to petroleum products or pesticides prior to his forty-
year employment at golf courses.

                                          - 12 -
J-S39014-17


circumstances. The fact that the experts arrive at different conclusions goes

to the weight of the evidence, not to its admissibility.

      The   court   looked   behind    Dr.     Brautbar’s   differential   diagnosis

methodology and challenged his conclusion that chromosomal abnormalities

in chromosomes 5 and 7 constituted strong evidence that Mr. Walsh’s AML

was caused by benzene exposure. The court noted that, while the studies

upon which Dr. Brautbar relied found a higher incidence of such aberrations

with chemical exposure, the aberrations were not conclusively linked to such

exposure. Furthermore, the court went on to opine, again without citing any

scientific support, that each of the following was scientifically unacceptable.

      1. “to use a study of bovine lymphocyte cultures as a basis for
         concluding that exposure to Touche causes AML in humans.”
         Trial Court Opinion, 10/5/16, at 10.

      2. “to use a study of mice bone marrow as a basis for concluding
         that exposure to Roundup causes AML in humans.” Id. at 11.

      3. To rely upon animal studies, test-tube studies, and studies
         that include significant limiting language as to the applicability
         of their results to causation theories. Id. at 12.

      4. To select portions of studies that favor a certain outcome while
         ignoring direct statements against that outcome contained
         within the same article.” Id. at 12-13.

      5. To rely on sources “predicting risk and establishing causation”
         as they “do not go hand-in-hand.” Id. at 3.

      As the foregoing conclusions illustrate, the trial court applied its own

view of what studies were scientifically/medically acceptable to support the

expert’s opinion. In doing so, the trial court impermissibly set itself up “as a


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J-S39014-17


super expert in the field of medicine.” Kubacki v. Metropolitan Life Ins.

Co., 164 A.2d 48, 52 (Pa.Super. 1960). That was not its role under Frye.

       The purpose of a Frye hearing is to permit a trial court to hear from

experts in the relevant scientific field whether an expert’s methodology is

generally accepted.6 As our Supreme Court acknowledged in Grady v. Frito

Lay, Inc., 839 A.2d 1038, 1044 (Pa. 2003), “one of the primary reasons we

embraced the Frye test in Topa was its assurance that judges would be

guided by scientists when assessing the reliability of a scientific method.” The

Court added, that “[g]iven the ever-increasing complexity of scientific

advances, this assurance is at least as compelling today as it was in 1977[.]”

Id. at 1045.      The Grady Court concluded that, “requiring judges to pay

deference to the conclusions of those who are in the best position to evaluate

the merits of scientific theory and technique when ruling on the admissibility

of scientific proof, as the Frye rule requires, is the better way of insuring that

only reliable expert scientific evidence is admitted at trial.” Id.

       Nor is an expert required to parrot the conclusions of study authors. As

Justice Castille cautioned in his dissent in Blum v. Merrell Dow Pharms.,

Inc., 764 A.2d 1, 15 (Pa. 2000), limiting an expert to the conclusions reached



____________________________________________


6 In lieu of a Frye hearing, the court ordered that depositions be taken of the
experts. Thereafter, the parties briefed and argued the merits of their
respective Frye positions. There is no indication that the trial court relied
upon the deposition testimony in arriving at its conclusions regarding
generally accepted scientific methodologies.

                                          - 14 -
J-S39014-17


by a study is a narrow approach that “conclusively determines that no opinion

other than the initial researcher’s may ever be heard.” He maintained that

we must allow room for expert medical opinion based on generally accepted

scientific principles.

       In support of the trial court’s Frye determination, Defendant Dow

Agrosciences contends that “any methodology based on ‘pesticides’ as a class,

and/or ‘chromosomal aberrations’ and cancer generally, involves too great of

an analytical leap to support admissible medical causation expert opinions” for

the products at issue. Brief of Dow Agrosciences at 30. Dow maintains that

Executor failed to submit epidemiology evidence supporting a specific link

between its product, Dursban, and AML, and asserts that there are no studies

demonstrating a connection.7 It contends that Dr. Brautbar failed to consider

alternative causes of AML for purposes of differential diagnosis, such as his

obesity. Thus, it contends, the trial court was correct in precluding the experts

under Frye.

       Deere & Company (“Deere”), the producer of Manicure, similarly alleges

that “Dr. Brautbar relies on mechanistic laboratory testing for his opinions[,]”

but failed to reference tests specific to whether Deere’s product, or what


____________________________________________


7 The record contains references to a 2004 peer-reviewed article discussing
adverse health effects among occupational users of Chlorphyrifos, the active
ingredient in Dursban. The authors of that article link Chlorphyrifos, an
organophosphate, to an increased risk of developing leukemia. Dursban also
contains petroleum solvents that are alleged to contain benzene, a known
carcinogen linked with AML.

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J-S39014-17


dosage of its product, could cause AML.            It criticizes Dr. Brautbar’s

methodology because he did not reference epidemiology studies involving

Chlorothalonil, a chemical in Manicure, which did not reveal a statistically

significant risk for leukemia. Deere alleges that the experts’ failure to address

such studies “shows gaps in their methodology.”            Deere’s brief at 6.

Furthermore, Deere argues that Dr. Brautbar’s reliance upon animal and in

vitro studies instead of the epidemiology studies involving humans is

inappropriate. BASF Corporation makes similar arguments with relation to its

product Touche’ and its active ingredient, vinclozolin.

      We glean the following from the record. Scientists routinely perform

animal and in vitro studies, as is evident from the number of such studies

undertaken. Dr. Brautbar did not rely solely on such studies. Dr. Brautbar

also relied upon case studies involving farmers, golf course superintendents,

workers, and pesticide applicators exposed to occupational pesticides.        In

addition, his opinions were informed by cytogenetic studies linking certain

genetic deletions with exposure to chemicals, together with his own

knowledge, education, and experience as a physician.

      Although the epidemiological studies cited by Executor’s experts did not

explore whether exposure to one particular pesticide product caused AML, we

reject Defendants’ contention that such specific studies were required in order

to survive a Frye scrutiny. The EPA assesses the cumulative risk of pesticides

that share common mechanisms of toxicity or act the same way in the body.


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Scientists have looked at multiple pesticide exposures in agricultural and

manufacturing settings, which one could argue provides a more accurate

picture of occupational exposure.     Executor’s epidemiological expert, Dr.

Zambelli-Weiner, explained that most epidemiological studies examine the

effects of multiple pesticide exposures because they are additive, cumulative,

and synergistic.    She concluded that epidemiological studies that have

examined the association between pesticide exposure and leukemia risk have

consistently shown a positive association, some estimates demonstrating a

two-fold increase in risk.   She opined, to a reasonable degree of scientific

certainty, that “organophosphate pesticide formulations, individually or in

combination, [are] causally related to an increased risk of leukemia in humans

exposed to them.”     Zambelli-Weiner Report, 7/18/12, at 15.       She opined

further that, “[e]pidemiologic studies support at least an additive effect on

risk of leukemia based on the independent effects of multiple pesticide

formulations including exposure to solvents.” Id. at 14.

      Thus, the scientific literature, in the aggregate, supports a causal

relationship between long-term pesticide exposure and leukemia, such as

AML. That link is not a mere scientific hunch. For purposes of Frye, an expert

need not rely on studies that mirror the exact facts under consideration. It is

sufficient if the synthesis of various legitimate studies reasonably permits the

conclusion reached by the expert. The absence of a treatise or study directly

on point goes to the weight, not the admissibility, of expert opinion.       An


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expert’s opinion will satisfy Frye when it is deduced from generally accepted

scientific principles and supported by studies or literature, even where the

expert could not point to one study involving parallel circumstances.

       The general scientific principle underlying the opinions of Dr. Zambelli-

Weiner and Dr. Brautbar is that long-term exposure to pesticides can cause

or increase the risk of leukemia, and specifically AML.     The literature and

studies, in the aggregate, support the general acceptance of that principle. In

addition, medical science in the form of cytogenetic studies linking changes in

certain chromosomes with exposure to chemicals supports a causal link.8 Dr.

Brautbar used the differential diagnosis theory, which is generally accepted in

the scientific community, to arrive at his opinion that long-term pesticide

exposure was the cause of Decedent’s AML. See In re Paoli R.R. Yard PCB

Litig., 35 F.3d 717, 756 (3d Cir. 1994) (affirming for purposes of the Frye

prong of the Daubert inquiry, that differential diagnosis is widely accepted

technique, subjected to peer review, used by the medical community to rule

in or out alternative causes).

       Defendants focus herein on the expert physician Dr. Brautbar’s inability

to quantify Mr. Walsh’s exposure to each specific product and to opine that

each of those exposure levels significantly or substantially increased the risk


____________________________________________


8 Although the trial court dismissed the cytogenetic studies as they were not
conclusive, we find the existence of those studies, together with the
differential etiology methodology employed by Dr. Brautbar, sufficient to pass
muster under Frye.

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J-S39014-17


of AML. That is not the proper subject for a Frye inquiry. An expert’s ability

to opine with a reasonable degree of scientific or medical certainty that

exposure to a particular defective product substantially caused or contributed

to the injury goes to the legal sufficiency of the expert testimony, not to

whether the science is generally accepted.9 Summary judgment, not Frye, is

the appropriate vehicle for addressing that question.10 See Howard v. A.W.

Chesterton Co., 78 A.3d 605, 607-08 (Pa. 2013) (per curiam).

       Our decision is in accord with Trach, supra at 1104, holding that since

Frye is an exclusionary rule of evidence, “it must be construed narrowly so as

not to impede admissibility of evidence that will aid the trier of fact in the

search for truth.”     For these reasons, we vacate both the order excluding

Executor’s experts from testifying, and the subsequent order granting

summary judgment in favor of Defendants based on that prior order, and

remand for further proceedings consistent with this opinion.



____________________________________________


9  Defendants’ focus on substantial factor and the “one breath” theory to
preclude Executors’ expert opinions under Frye is misplaced. The record
establishes frequent, regular, and proximate exposure to the pesticides at
issue herein. Dr. Brautbar relied upon that exposure history, together with
Decedent’s medical history, epidemiological studies, and cytogenetic studies,
in arriving at his conclusion that Decedent’s forty-year exposure to
Defendants’ pesticides caused or contributed to his death from AML.

10 Prior to the Frye challenge, summary judgment was granted in favor of
several of the original defendants due to a lack of expert testimony identifying
their products as substantial contributing factors in Mr. Walsh’s death. As to
the Defendants remaining herein, the expert proof was sufficient to survive
that scrutiny.

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J-S39014-17


      Orders vacated and case remanded for further proceedings. Jurisdiction

relinquished.

      Judge Strassburger joins the opinion.

      PJE Bender files a dissenting opinion.

Judgment Entered.




Joseph D. Seletyn, Esq.
Prothonotary



Date: 6/20/2018




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