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Pritchard v. Dow Agro Sciences

March 11, 2010


The opinion of the court was delivered by: Judge Nora Barry Fischer



Presently before the Court is Defendants Dow Agro Sciences ("Dow") and Southern Mill Creek Products of Ohio's ("Southern Mill") Daubert motion challenging Plaintiffs Robert T. Pritchard and Elizabeth Ann Pritchard's proffer of expert testimony by Dr. Bennet Omalu. (Docket No. 127). Dr. Omalu opines that Mr. Pritchard's exposure to Dursban products, which were manufactured and sold by Defendants, caused him to develop Non-Hodgkin's Lymphoma ("NHL"). Defendants maintain that Dr. Omalu is not qualified to render his opinions in this case. They also argue that Dr. Omalu's opinions regarding both general causation and specific causation do not meet the reliability standards set forth in Daubert v. Merrell Dow Pharms., Inc., 509 U.S. 579 (1993), and incorporated into Federal Rule of Evidence 702, and that his opinions do not fit the facts of this case.

The motion has been fully briefed and the Court heard oral argument*fn1 from counsel on November 17, 2009. Upon consideration of the parties' arguments, and for the following reasons, Defendants' motion [127] is GRANTED.


A. Factual Summary

The instant lawsuit is a toxic tort case in which Mr. Pritchard and his wife allege that chemicals manufactured and sold by Defendants Dow and Southern Mill caused Mr. Pritchard to develop NHL. (Docket No. 23 at ¶¶ 7-10, 20). Mr. Pritchard asserts claims of negligence and strict liability against Defendants, while Mrs. Pritchard asserts a claim for loss of consortium. (Docket No. 23). Plaintiffs do not claim any injuries to Mr. Pritchard caused by Defendants except those resulting from his development of NHL. (Docket No. 128-1, Exhibit 2, Email from David Rodes, Esq. to William Padgett, Esq. at 1).

Mr. Pritchard was diagnosed with NHL, specifically Diffuse Large B-Cell Lymphoma, not otherwise specified ("DLBCL NOS"), a form of cancer, in August of 2005. (Docket No. 128-1, Exhibit 3, Plaintiffs' Answers to Dow Agro Sciences LLC's First Set of Interrogatories to Plaintiffs dated Aug. 25, 2008). After treatment, his NHL went into remission in November of 2005. (Id.).

The parties do not dispute that Mr. Pritchard was diagnosed with NHL or DLBCL NOS. (Docket No. 152 at 42). The dispute surrounds whether Mr. Pritchard's exposure to Dursban products, and its active ingredients, including chlorpyrifos, is a legal cause of his disease.

The National Cancer Institute defines NHL as "[a]ny of a large group of cancers of lymphocytes (white blood cells)." Non-Hodgkin['s] Lymphoma, National Cancer Institute, available at: (last visited 3/5/10). NHL is a cancer that begins in cells of the immune system and can affect most areas of the human body. What You Need to Know About Non-Hodgkin['s] Lymphoma, National Cancer Institute, U.S. Department of Health and Human Services, National Institute of Health, at 2-3, available at: (last visited 3/5/10). DLBCL is "[a] type of B-cell non-Hodgkin['s] lymphoma (cancer of the immune system) that is usually aggressive (fastgrowing). It is the most common type of non-Hodgkin['s] lymphoma, and is marked by rapidly growing tumors in the lymph nodes, spleen, liver, bone marrow, or other organs. Other symptoms include fever, night sweats, and weight loss. There are several subtypes of diffuse large B-cell lymphoma." Id. at 32. One of the subtypes of DLCBL is DLCBL NOS. (Docket No. 128-5, Exhibit 11, International Agency for Research on Cancer, WHO Classification of Tumours of Haematopoietic and Lymphoid Tissues ("WHO Classification Study"), at 233 (4th ed. 2008)). The American Cancer Society estimated that 65,980 new cases of NHL would occur in 2009. (Docket No. 128-1, Exhibit 5, American Cancer Society, Cancer Facts & Figures Excerpt -2009 ("ACS Excerpt") at 15). The incidences of NHL have nearly doubled since the 1970s. Id. This increase is largely unexplained. Id. The World Health Organization estimates that 25-30% of adult NHLs in western countries are DLCBL NOS. WHO Classification Study at 233.

The etiologies or causes of NHL and its subtype, DCLCBL NOS, are generally unknown. Id.; see also ACS Excerpt at 15. But, several risk factors have been identified, including: people with severe immunodeficiency, human immunodeficiency virus (HIV), human T-cell leukemia virus type 1, hepatitis C virus; a family history of NHL; and occupational exposure to herbicides, chlorinated organic compounds and certain other chemicals. Id.

Dursban is a registered trademark owned by Dow Agro Sciences LLC. (Docket No. 128 at 4). "Dursban is the trade name for a group of insecticide products containing chlorpyrifos as the active ingredient." (Id.). The other ingredients in Dursban are Xylene-range aromatic solvents including Xylene, Cumene, and Ethyltoluene. (Docket No. 128-9, Material Safety Data Sheet for Dursban L.O. Insecticide). "Chlorpyrifos was widely used in U.S. households until 2000, when the U.S. Environmental Protection Agency revised its risk assessment of this and other organophosphate pesticides and phased out or eliminated certain residential uses." (Docket No. 138-5, Won Jin Lee et al., Cancer Incidence Among Pesticide Applicators Exposed to Chlorpyrifos in the Agricultural Health Study ("2004 Lee Study"), 96 J. Nat. Cancer Inst. 1781 (2004) at 1). Among other chemicals evaluated, the EPA has classified chlorpyrifos in Group E: Evidence of Non-Carcinogenicity for Humans. (Docket No. 128-9, Exhibit 24, List of Chemicals Evaluated for Carcinogenic Potential). The other categories include Group A: Human Carcinogen; Group B1: Probable Human Carcinogen; Group C: Possible Human Carcinogen; and, Group D: Not Classifiable as to Human Carcinogenicity. (Id.).

B. Procedural History as to the Instant Motion

In support of their claim that Mr. Pritchard's exposure to Dursban caused his NHL, Plaintiffs identified Dr. Bennet Omalu as their expert on medical causation and submitted his expert report to Defendants on June 1, 2009. (Dr. Omalu Report at 1). Thereafter, Plaintiffs supplemented Dr. Omalu's expert report by providing Defendants with a series of articles upon which Dr. Omalu relied. Dr. Omalu was then deposed on June 26, 2009. (Docket No. 128-1, Dr. Omalu deposition at 1).

Defendants filed their Motion to Exclude the Expert Causation Testimony of Dr. Bennet Omalu on July 22, 2009. (Docket No. 127). In support of their motion, Defendants attached voluminous exhibits including rebuttal experts reports authored by Marshall A. Lichtman, M.D., Seymour Grufferman, M.D. and Michael Greenberg, M.D. (Docket Nos. 128-1 through128-9). Plaintiffs filed their Brief in Opposition to Defendants' Motion to Exclude on August 28, 2009, attaching the "Declaration of Bennet I. Omalu, MD, MBA, MPH." (Docket No. 135).*fn3 In response, Defendants filed their Reply brief on November 2, 2009, and a second appendix, including a rebuttal declaration from Seymour Grufferman, M.D. (Docket No. 149). The Court held a Daubert hearing on November 17, 2009 during which the parties presented no additional evidence, only arguing the legal issues in dispute.

After the Daubert hearing, the parties submitted supplemental briefing on whether the exclusion of Dr. Omalu's testimony violated the Erie doctrine, an argument which was raised and then more fully developed by Plaintiffs at the hearing. See Erie Railroad Co. v. Tompkins, 304 U.S. 64, 78 (1938). Defendants filed their supplemental brief on January 4, 2010, while Plaintiffs submitted their supplemental brief on January 25, 2010. (Docket Nos. 154, 155).

In sum, the proffer of Dr. Omalu's testimony consists of opinions outlined in his expert report, portions of his deposition testimony and his declaration. Defendants take issue with this proffer.


In this action, both parties test the boundaries of Federal Rule of Evidence 702 and Daubert and the admissibility of a medical causation opinion by an expert in a toxic tort case. Defendants take a restrictive view of Rule 702, Daubert and its progeny, arguing that several deficiencies in Dr. Omalu's proffered testimony independently render his opinions per se inadmissible, requiring exclusion of Dr. Omalu without further analysis. Plaintiffs' position is much more liberal, and they maintain that their proffer is sufficient to meet the minimal requirements of Rule 702, Daubert and its progeny, arguing that Dr. Omalu's testimony should not be excluded. Alternatively, Plaintiffs contend that the application of certain principles advocated by Defendants violates the Erie doctrine. The Court has carefully considered the parties' respective positions and, based on the present record, finds that the methodology used by Dr. Omalu in reaching his opinions in this case is not reliable and, even if it was found to be reliable, his opinions are too speculative to "fit" the facts of this case. Accordingly, Plaintiffs have failed to establish that there are "good grounds" for permitting him to so testify.

A. Legal Standard

Federal Rule of Evidence 702, which memorializes the Supreme Court's landmark case Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579 (1993), provides the basic framework for the admissibility of expert testimony:

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, if (1) the testimony is based upon sufficient facts or data, (2) the testimony is the product of reliable principles and methods, and (3) the witness has applied the principles and methods reliably to the facts of the case.

FED.R.EVID. 702.*fn4 The United States Court of Appeals for the Third Circuit has held that "Rule 702 embodies a trilogy of restrictions on expert testimony: qualification, reliability and fit." Schneider ex rel. Estate of Schneider v. Fried, 320 F.3d 396, 404 (3d Cir. 2003)(citations omitted). "[T]he district court acts as a gatekeeper, preventing opinion testimony that does not meet the requirements of qualification, reliability and fit from reaching the jury." Id. In this role, the district court is not the finder of fact but must focus on the methodology of the expert in order to "satisfy itself that 'good grounds' exist for the expert's opinion." United States v. Mitchell, 365 F.3d 215, 244 (3d Cir. 2004) (citing Daubert, 509 U.S. at 590, 113 S.Ct. 2786); In re TMI Litigation, 193 F.3d 613, 713 (3d Cir. 1999)(district court should not conflate "its gatekeeping function with the fact-finders' function as the assessor of credibility").

Daubert does not require that a party who proffers expert testimony carry the burden of proving to the judge that the expert's assessment of the situation is correct. As long as an expert's scientific testimony rests upon "good grounds, based on what is known," it should be tested by the adversary process-competing expert testimony and active cross-examination-rather than excluded from jurors' scrutiny for fear that they will not grasp its complexities or satisfactorily weigh its inadequacies. In short, Daubert neither requires nor empowers trial courts to determine which of several competing scientific theories has the best provenance. It demands only that the proponent of the evidence show that the expert's conclusion has been arrived at in a scientifically sound and methodologically reliable fashion.

Mitchell, 365 F.3d at 244 (quoting Ruiz-Troche v. Pepsi Cola Bottling Co., 161 F.3d 77, 85 (1st Cir. 1998)(citations omitted)); see also Kannankeril v. Terminix Intern., Inc., 128 F.3d 802, 809 (3d Cir. 1997)("The trial judge must be careful not to mistake credibility questions for admissibility questions.").

Finally, the party asserting the admissibility of the proffered testimony has the burden to demonstrate by a preponderance of the evidence that the opinions are based on "good grounds." Kannankeril, 128 F.3d at 807.

B. Expert Opinions

1. Plaintiffs' Expert - Dr. Bennet I. Omalu

Dr. Bennet I. Omalu is currently the Chief Medical Examiner of San Joaquin County, California and was formerly the Attending Forensic Pathologist and Neuropathologist in the Allegheny County Coroner's Office from 2002 until 2007. (Docket No. 128-9, Exhibit 31, Robert T. Pritchard, Sr., Medico-Legal Report by Dr. Bennet I. Omalu ("Dr. Omalu Report") at 1, 5). He is also co-director of the Brain Injury Division at the Rockefeller Institute of Neuroscience, and an Associate Clinical Professor of Pathology at the University of California, Davis. (Id. at 5). He is board certified in Anatomic Pathology, Clinical Pathology, Forensic Pathology and Neuropathology and has a Master's degree in Public Health-Epidemiology from the University of Pittsburgh. (Id.). He is licensed to practice in Indiana, Pennsylvania, Hawaii, and California. Thus, Dr. Omalu has significant expertise in the fields of pathology and epidemiology.

Dr. Omalu prepared an expert report for purposes of this litigation. He did not conduct a physical exam of Mr. Pritchard, nor did he meet with him. (Dr. Omalu Deposition at 43, 246). Prior to preparing his report, Dr. Omalu reviewed the following documents: Plaintiffs' Second Amended Complaint; a medical report by Dr. Emilio Navarro, MD*fn5, dated April 22, 2008; a surgical pathology report, S-05-0009357, from the Uniontown Hospital Laboratory, Uniontown, Pennsylvania, dated September 1, 2005; and, a Material Safety Data Sheet ("MSDS") on Dursban L.O. Insecticide from Dow AgroSciences, Calgary, Alberta. (Omalu Report at 2). Dr. Omalu admitted that he did not review all of Mr. Pritchard's medical records, testifying that he did not believe it was necessary in order to render his opinions. (Dr. Omalu Deposition at 38-40, 41-44). He also did not review any of Mr. Pritchard's pesticide application records, Plaintiffs' discovery responses, Mr. Pritchard's deposition transcript, all of which contain information regarding the extent of Mr. Pritchard's exposure to Dursban and other pesticides, or any documents related to Dursban products other than the MSDS sheet on Dursban L.O. (Dr. Omalu Deposition at 45-55).

In his Report, Dr. Omalu concludes that Mr. Pritchard's "prolonged occupational exposure to Dursban insecticides significantly contributed to the patho-etiology of his Non-Hodgkin's Lymphoma."*fn6 (Dr. Omalu Report at 2). Dr. Omalu first describes the general risk of exposure to pesticides to humans, stating that "[a]ssessment of the risk of agricultural toxins, insecticides and herbicides to humans has shown that these chemicals are highly toxic and dangerous and have been identified as human carcinogens." (Dr. Omalu Report at 2). He opines that "no level of exposure to agricultural chemicals should be deemed safe" because they are not indigenous to the human body, and are identified as "foreign" by all types of human cells, especially cells of the immune system, noting that Mr. Pritchard's illness is cancer of the immune system. (Id).

Dr. Omalu next explains the chemical composition of Dursban insecticides, which include Chlorpyrifos, Xylene,*fn7 Cumene*fn8 and Ethyltoluene.*fn9 (Id.) In his view, "[c]hlorpyrifos is an organophosphate compound, which is an irreversible inhibitor of the acetylcholinesterase enzyme."*fn10

(Dr. Omalu Report at 3). He further states that "it is common knowledge in medicine that acute and chronic exposure to organophosphate compounds cause multisystem toxic effects," resulting in a litany of diseases and symptoms, several of which Mr. Pritchard has been found to have, including neuropathy, fatigue, bipolar disorder, tremors, difficulty concentrating and liver disorder. (Id.). Dr. Omalu opines that these diagnosed diseases and symptoms were caused by Mr. Pritchard's exposure to Dursban. (Id.). He also describes the chemical composition of Xylene, Cumene, and Ethyltoluene, concluding that their respective chemical compositions makes them each "benzene derivatives." (Id.).

Dr. Omalu then discusses the known risk factors of Non-Hodgkin's Lymphoma, concluding that exposure to agricultural chemicals like Dursban, organophosphate compounds, and benzene derivatives, has been shown to have an increased incidence of Non-Hodgkin's Lymphoma. Specifically, he opines that:

[a] number of environmental factors have been implicated in the occurrence of Non-Hodgkin's Lymphoma, including infectious agents, chemical exposures, and medical treatments. Many reports have demonstrated an association between exposure to agricultural chemicals like Dursban, which contain compounds like the organophosphate compounds, and an increased incidence of NonHodgkin's Lymphoma.

Compounds found in insecticides and agricultural solvents like Dursban, including organosphate compounds and benzene derivatives, induce chronic genotoxic and mutational carcinogenic effects on a broad variety of human cells, which initiate a broad variety of cancers including lymphomas and the type of cancer Mr. Pritchard is suffering from. Dursban contains an organophosphate compound and at least three benzene derivatives; Xylene, Cumene and Ethyltoluene. Benzene and other toxic compounds are expected to be contaminants in solvents, which contain benzene derivatives and organic compounds. This is a natural phenomenon observed in chemical behavior of organic compounds and solvents in-vivo and in-vitro. (Id. (emphasis in original)). Dr. Omalu compares his toxicity theory to the numerous opiate derivatives which are found in the blood of heroin abusers despite their having only consumed heroin and not any of the derivatives. (Id.). He explains that: the human body converts chemical compounds into a myriad of intermediate metabolites, which frequently exhibit novel and independent actions and toxic effects. The cumulative effects of a compound cannot only be determined by the known direct effects of the parent ...

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