Articles & Updates

Genuine Science or Unscientific Speculation Offered by a Genuine Scientist?

Jan 17, 2008 | Articles & Updates

By: Edwin B. Palmer, Esq.


Cancer, toxic brain injury, manganism, multiple chemical sensitivity, mixed dust injuries. The toxic torts landscape is continually broadening as those developing and advocating this ever-expanding list of new causes of action grow increasingly bold in attempts to capitalize on the public’s concern with environmental issues and post-Enron suspicion of corporations. Often, private toxic torts lawsuits are not the product of strong causation or evidence of harm, but are instead the result of the “me, too” response to the widespread publicity these lawsuits generate. These lawsuits are increasingly propagated by litigation-generated “science” and are funded and initiated for the purpose of perpetuating the litigation and overcoming Daubert/Frye admissibility limitations and, ultimately, taking the case to a Jury.

It is well-established that in any negligence action, with regard to claims of physical injury or impairment, expert medical testimony is necessary to establish the causal nexus of the injury to the alleged tortious conduct in those cases where the connection is not obvious and is beyond the knowledge of the average layperson.1 The need for expert medical testimony is particularly acute in toxic tort litigation where the plaintiff is typically alleging an illness that develops years, if not decades, after exposure to a toxic substance. In toxic tort cases, expert testimony is necessary to establish both that the substance at issue is capable of causing the particular condition or injury alleged and that the Plaintiff was exposed to that substance at sufficient levels to cause the individual’s particular injury.

Despite these clear mandates, it is not uncommon for plaintiffs and experts advocating on their behalf to completely ignore the requirement that they document their client’s exposures levels. On other occasions, experts attempt to advance their conclusions based on questionable science that fails to employ scientifically valid methodology. Despite these attempted short cuts, as several recent Court decisions show, the Judiciary continues to take seriously its “gatekeeper” obligation to keep “junk science” out of the courtroom.

In re: Toxic Substance Cases (Pennsylvania)

In August 2006, Judge Robert Colville of the Allegheny County Court of Common Pleas issued a lengthy opinion addressing the admissibility, under Frye, of the testimony that each plaintiff?s exposures to the defendants? asbestos-containing friction brake products was the proximate cause in the development of the plaintiff’s asbestos-related disease.2 This conclusion by plaintiffs’ experts was essentially based on the premise that “every single exposure to every asbestos product is a proximate cause of a subsequently diagnosed asbestos-related injury.”3 The Court’s inquiry in this matter revolved around the issue of dose, namely: “how much greater quantity of exposure [to asbestos above ambient background levels] is necessary to permit the causal attribution of an asbestos-related disease to a particular asbestos exposure.”

In evaluating the admissibility of the proffered testimony under Frye, Judge Colville was skeptical of the experts’ reliance on case reports, noting that “case reports are nothing more than reports by other physicians and professionals confirming the development of a disease in an individual patient with additional information about that patient.”5 In the opinion of the Court, case reports, standing alone, cannot support causal attribution as they “only report associations – causal correlations. Sometimes an association exists because there is a causal correlation. Sometimes associations exist because there is a coincidence, and nothing more.”6 Rather, the scientific method must be employed to distinguish “coincidental associations” from “causal correlations.” Short of empirical verification, reliance on case reports is an insufficient basis to meaningfully support a causation opinion.7

The Court next addressed the crux of plaintiffs’ experts’ theory “that an asbestos-related disease dose response curve applies even where there is a vanishingly small exposure.”8 The Court, relying on “common sense” and “common experience” rejected the “extrapolation down” theory posited by plaintiffs’ experts:

[w]hile it may be a valid assertion that: if high dose asbestos exposure is bad for you, then low dose asbestos exposure may potentially be bad for you; it is not a valid assertion that because high dose exposure to asbestos is bad for you, then low dose exposure to asbestos is, in fact, bad for you or that a specific plaintiff’s exposure at an unknown low dose exposure level, in fact, contributed to that plaintiff’s asbestos-related disease.9

In sum, “dose response curves, based upon generally accepted scientific methodology, for “low dose” exposures – simply do not exist.”10 Because generally accepted scientific methodology at the time of this case was not able to demonstrate the effect of low dose exposures on the body, plaintiff’s experts opinions were merely the doctors’ “best guesses” unverified by generally accepted methodology.

The Court left open the possibility that the outcome would be different if plaintiffs’ experts had presented biological findings to support their claims, or quantitative evidence of “high dose” exposure. However, at no point, did the experts attempt to “meaningfully quantify the actual or even approximate amount” of the plaintiffs’ asbestos exposure, nor do they “attempt to delineate a threshold exposure, or even a potential range for a threshold exposure” that they believe would be required to support causation.11

Parker v. Mobil Oil Corporation (New York)

In 1999 Eric Parker, a gas station attendant commenced a lawsuit against Mobil Oil Corporation and other gas companies alleging that exposure to benzene in gasoline caused him to develop acute myelogenous leukemia (AML). Parker contended that during his 17 years of employment at several full-service stations, he was exposed to benzene on a daily basis through inhalation of gasoline fumes and through skin contact with the gasoline.

In support of his claim, Plaintiff retained two experts, an expert in occupational medicine and epidemiology, and an expert in toxicology and epidemiology. Plaintiff’s occupational medicine physician noted that Parker was “frequently” exposed to “excessive” quantities of gasoline and had “extensive exposures in both liquid and vapor form.”12 Additionally, he noted that several epidemiological studies found an increased risk of leukemia in petroleum refinery workers exposed to benzene. The expert concluded that Parker would not have contracted AML in the absence of his specific occupational exposure to benzene. Plaintiff’s second expert stated that Parker had a greater exposure to benzene than workers in the refinery studies which had established an association between benzene and leukemia. Neither of Plaintiff?s experts quantified, nor attempted to quantify, Parker?s exposure to benzene from gasoline.

The trial court, while recognizing that Parker’s experts: (1) failed to cite any studies establishing a causal connection between AML and gasoline; and (2) did not quantify Parker’s exposure to benzene in gasoline, nonetheless admitted their testimony on the basis that the experts distinguished studies finding an increased risk of leukemia in benzene-exposed refinery workers from studies finding no association. Additionally, the trial court held that while the failure to quantify Parker?s exposure may require a Frye hearing in some cases where there was less exposure, it was not necessary in this matter given Parker’s descriptions of his exposures. Finally the trial court accepted the experts’ theory that “there is no threshold of exposure [to benzene] under which there will be no negative effects to health.”13

On appeal, the Appellate Division reversed. The court reasoned that as Parker’s experts failed to: (1) quantify his exposure to benzene; (2) establish a dose-response threshold; or (3) show that Parker’s exposures exceeded any threshold. As such, any conclusions as to the amount of Parker’s exposure would be inadmissible as speculative and unreliable. The Court also rejected the premise that there is no threshold of exposure to benzene below which leukemia would not occur: “the scientific reliability of th[at] methodology has flatly been rejected as merely a hypothesis.”14

On appeal, the New York Court of Appeals affirmed the Appellate Division choosing not to address the admissibility of the experts’ opinions on Frye grounds, on the basis that there was no novel methodology at issue. Instead, the Court examined the reliability of the specific methodology employed by Parker’s experts, identifying the issue as whether Parker’s experts “provided a reliable causation opinion without using a dose-response relationship and without quantifying Parker’s exposure.”15 The Court of Appeals concluded that the proffered testimony of Parker’s experts did not have an adequate foundation to be admissible.

The Court concluded that it is not always necessary for a plaintiff to precisely quantify exposure levels or use the dose-response relationship so long at the method used by the expert to establish causation is generally accepted in the scientific community. However, in the case of Parker’s experts, the Court concluded that they failed to demonstrate that exposure to benzene in gasoline caused Parker’s injury. Plaintiff’s toxicology expert’s conclusory statement – based on the Plaintiff’s deposition testimony that he had “far more exposure to benzene than did the refinery workers in epidemiological studies” was plainly insufficient to establish causation.” Because Plaintiff’s toxicologist failed to quantify the refinery workers’ level of exposure or explain how Parker’s exposure to benzene exceeded that of refinery workers, his conclusion lacked the necessary epidemiologic evidence to support his opinion.

The testimony of Parker’s occupational medicine expert was also excluded. His vague statements that the Plaintiff was “frequently” exposed to “excessive” amounts of benzene were lacking sufficient foundation to be admissible, as they could not “be characterized as a scientific expression of Parker’s exposure level.” Additionally, the doctor’s reliance on studies of refinery workers finding an increased risk of leukemia was also insufficient, as the studies failed to address the issue of whether there was any relationship between exposure to gasoline and AML.

Korte v. ExxonMobil Coal USA, Inc. (United States Court of Appeals for the 7th Circuit)

It is also clear that while precise quantification of a Plaintiff’s exposures is not necessary – as long as evidence of the Plaintiff’s exposure is scientifically and sufficiently expressed to establish causation – such evidence, where available, cannot be ignored.

In Korte v. ExxonMobil,17 Plaintiffs (husband and wife) filed suit alleging that they developed various symptoms including chronic sore throat, eye irritation and tearing, indigestion, diarrhea and fatigue as a consequence of exposures to airborne dust blown off two coal refuse disposal areas (RDAs) owned by Exxon and located less than one mile away from the Kortes’ farm. The Kortes proffered the testimony of an occupational medicine physician who opined in his report that ?it is likely that? the Kortes’ symptoms “may be caused by” their exposures to coal dust. In support of his conclusions, the expert relied on the Kortes’ account of dust exposure, their medical histories, pictures and video of dust being blown off the RDAs, and his own knowledge of the effects of coal dust exposure. Plaintiff?s expert did not conduct any medical tests, including blood tests, toxicological tests or allergy tests. The doctor conceded that he could not be certain that the dust described by the Kortes and shown in the videotape contained any coal dust. Additionally, he did not conduct any tests on the dust from the Kortes’ property, nor did he consider testing by the Illinois Environmental Protection Agency (IEPA) or Illinois Department of Public Health (IDPH) on dust found inside and outside the Kortes’ home which did not detect the presence of any inorganic compounds above health guidelines.

On appeal, the United States Court of Appeals for the Seventh Circuit affirmed the trial court’s exclusion of Plaintiff’s expert under Daubert. Fatal to Plaintiff’s cause was the fact that their expert opined as to the cause of the Kortes’ symptoms “based on the subjective beliefs of the Korte family that they had been exposed to coal dust” from the RDAs without undertaking to confirm the validity of this premise:

Plaintiff’s expert did not rely on tests conducted on dust found in or around the Kortes’ property. [He] did not know the chemical composition of the dust on the Kortes’ property, and could not verify that the dust emanated from Exxon?s RDAs. [He] also did not conduct or rely on tests measuring the amount of exposure in order to opine “whether the dose to which the plaintiff was exposed is sufficient to cause the disease.”18

Additionally, the doctor’s methodology was found lacking, as he failed to properly exclude alternative causes for the Plaintiffs’ symptoms, including Mr. Korte’s 35 pack-year smoking history, pesticides, allergies or exposures to dust containing dirt, gravel and other background levels of inorganic chemicals.

Lessons Learned – Properly Documenting Exposures

As the cases above demonstrate, as do numerous other cases not discussed herein, a failure to quantify, or even to attempt to quantify a plaintiff’s exposure to a harmful substance will most likely prove fatal to the plaintiff?s claim.19 A plaintiff’s expert must demonstrate an exposure to a quality or quantity of exposure from which a jury might reasonably infer that the plaintiff suffered an injury from the claimed exposure. At a minimum, expert testimony should include a description of the method used to arrive at the level of exposure and scientific data supporting the determination. In the absence of supporting scientific data, an expert’s conclusions are simply “best guesses.” “Guesses, even if educated, are insufficient to prove the level of exposure in a toxic tort case.”20 While Courts do not require plaintiffs to precisely quantify their exposures to a toxin, any causation opinion must be based on sufficient information concerning the level of exposure in order to be admissible.

Any expression of level of exposure must be arrived at using sound scientific methodology, and employing techniques subject to objective, independent validation in the scientific community. Reliance on anecdotal descriptions of exposure such as a plaintiff’s self-reported exposure assessment gleaned from deposition testimony, conversations with the plaintiff, or plaintiff’s counsel’s description of the plaintiff’s work activities, without consideration of independently verifiable information such as exposure data or work records, is unacceptable methodology.

Additionally, while reliance on epidemiologic literature, though not required, is generally advantageous, the studies cited must reasonably support the expert’s ultimate opinion. It should be assumed that courts will consider the scientific literature relied upon by a party’s experts, sometimes with a very critical eye.21 As shown by Judge Colville’s opinion in the Toxic Substance cases, some courts have looked at case reports with skepticism. However, even case-control studies and other epidemiologic studies will not get an expert over the admissibility hurdle if the cited literature is not reliable and does not provide an adequate basis of the expert’s ultimate opinion.22

Finally, while an exposure assessment grounded in sound science is a necessary element of proving causation, practitioners should keep in mind that consideration still must be given to other factors affecting the reliability of the expert’s methodology such as (1) the timing of the exposure in relationship to the onset of the Plaintiff’s medical condition (i.e. Did the Plaintiff’s disease develop within the expected latency period – Did the Plaintiff’s condition manifest itself before the exposure?) and (2) whether there are alternative etiologies (e.g. genetics, smoking, hobbies and other avocational exposures, etc.) that can be properly ruled out.

While the Courts in the above-discussed cases excluded the proffered expert testimony, these cases, and others, provide some insight into what exposure assessment methodologies might pass muster, including: (1) biological findings (such as high “fiber loads” or blood lead levels?); (2) consideration of documented symptoms of over-exposure experienced by the Plaintiff or his co-workers; and (3) consideration of the work processes and work facility design and whether they are likely to contribute to overexposures. Obviously, when it is available, actual exposure documentation, either from a company’s industrial hygiene testing or testing from regulatory agencies, may be the best source of exposure information. Moreover, where such evidence is available, as in Korte, it must be considered, (even if not ultimately relied upon) by the expert in arriving at his opinion. Bear in mind that employing some or all of these techniques does not guarantee admissibility if proper scientific methodology is not use and/or if the results do not reasonably and reliably support the expert’s conclusions.

* * *

In summary, while courts recognize the inherent difficulty in quantifying the exact dosage an individual plaintiff received from exposure to an individual substance, an attempt must be made to scientifically express that the plaintiff was exposed to an amount of that substance sufficient to cause the kind of harm of which he or she complains. The challenge, as the Parker Court noted, is striking a balance between “allowing unreliable or speculative information (“junk science”) to go before the jury with the weight of an impressively credentialed expert behind it . . . [and setting] an insurmountable standard that would effectively deprive toxic tort plaintiffs of their day in court.”23 The cases discussed above have struck the right balance.


1 See, e.g., Hamil v. Bashline, 481 Pa. 256, 266, 392 A.2d 1280, 1285 (1978).

2 In re: Toxic Substance Cases, No. A.D. 03-319, slip op. (Pa. Com. Pl. Aug. 17, 2006). The case has been appealed and is presently pending before the Pennsylvania Superior Court.

3 Id. at p. 2.

4 Id. at p. 7.

5 Id. at p. 9.

6 Id.

7 Id. at p. 11.

8 Id. at p. 12.

9 Id. at p. 14.

10 Id. at p. 13.

11 Id. at p. 25.

12 Parker v. Mobil Oil Corporation, 7 N.Y.3d 434, 449 (2006).

13 Id. at 445.

14 Id. at 446, citing Appellate Division opinion, 793 N.Y.S.2d 434 (2005).

15 Id. at 447.

16 Id. at 449.

17 Korte v. ExxonMoibil Coal USA, Inc., 164 Fed.Appx. 553 (7th Cir. 2006).

18 Id. at 557.

19 See e.g., McClain v. Metabolife Int’l, Inc., 401 F.3d. 1233, 1241 (11th Cir. 2005) (To carry the burden in a toxic tort case, a plaintiff must demonstrate the levels of exposure that are hazardous to human beings generally as well as the plaintiff’s actual level of exposure to the defendant’s toxic substance before he or she may recover.); Benkwith v. Matrixx Initiatives, Inc. 467 F.Supp.2d 1316, 1328 (M.D. Ala. 2006) (“reliability of expert’s methodology is suspect if she avoids or neglects the dose-response relationship”); Matt Dietz Co. v. Torres, 198 S.W.3d 798, 804 (Tex. App. 2006) (Expert’s reliance on “heavy dusty exposure which could be seen on clothing” as proof of substantial exposure was insufficient to establish causation.)

20 Mitchell v. Gencorp Inc., 165 F.3d 778, 781 (10th Cir. 1989).

21 See e.g., Knight v. Kirby Inland Marine, Inc. __ F.3d __ (5th Cir. 2007).

22 See e.g., Id., Parker v. Mobil Oil Corporation, supra.

23 7 N.Y.3d at 447.