TORTINI

For your delectation and delight, desultory dicta on the law of delicts.

The Recrudescence of Ferebee – Part Two

July 1st, 2026

In 2010, almost 30 years after Ferebee was decided, the Solicitor General cited the case in an amicus brief before the Supreme Court case, in Matrixx Iniatives, Inc. v. Siracusano. The case was a securities fraud class action, which was dismissed initially by the trial court on consideration of the defendant’s motion that the complaint failed to allege causation supported by statistically significant studies. The Supreme Court would go on unanimously to reject causation as a criterion for establishing a prima facie case of securities fraud, which made statistical significance irrelevant. Because the FDA could (and later did) require the company to recall its product upon a showing that material evidence suggested that there might be a possible causally induced harm, the Court held that the plaintiff class did not have to allege causation.[1] The harm to the shareholders came in the form of management’s bullish financial projections for a product that was later recalled for safety concerns, even if the recalled product never was shown to cause any harm. The Solicitor General’s amicus brief advanced the Ferebee case as an example of a causal relationship that could be established “through consideration of multiple factors independent of statistical significance.”[2] Although the government’s amicus brief correctly discerned that the causal connection between paraquat exposure and pulmonary fibrosis was established without analytical epidemiologic studies, and the necessary tools of statistical analysis for such studies, the brief mistakenly placed the allegations that Zycam caused anosmia in the same conceptual framework as paraquat. Unlike paraquat toxicity, millions of people used Zycam for relief from cold and flu symptoms, and the alleged harm, anosmia, commonly occurs in the aftermath of colds and flu. The Zycam personal injury claims fared poorly in litigation because of the dearth of supportive evidence that was appropriate to support causation, as opposed to materiality in securities law.[3]

The Ferebee case correctly observed that epidemiology was not necessary to establish the causal claim involving paraquat dermal exposure and lung toxicity and fibrosis. At the time that Mr. Ferebee sustained extensive paraquat exposure as a result of his governmental employer’s extreme negligence, the scientific community fully accepted that paraquat exposure, by ingestion, inhalation, or dermal exposure caused systemic toxicity and deleterious lung effects. This “general causation” had been established by case reports and case series, along with studies of paraquat’s metabolic fate and distribution in humans and non-human animals (including non-human primates), and assessment of mechanistic effects in cells and tissues of the target organs affected by paraquat when it became systemically distributed in the human body.

About the time of the Ferebee litigation, a textbook on agricultural chemicals described the toxic effects of dipyridyl compounds in humans, including paraquat:

“Human Toxicology Experience: A considerable amount of clinical experience has been reported in the literature with over 100 cases of illness and/or death. The chemical is unique in the sense that there is not only an acute toxicity syndrome but, in addition, it has the ability to produce a delayed fibroblastic response in the lungs. The latter is usually the principal mechanism of death.

For industrial workers, paraquat is not considered very dangerous. Inhalation hazard is extremely low due to the low vapor pressure of the chemical. Nevertheless, protective respiratory equipment should be used particularly when other atmospheric contamination might occur. * * * On no occasion should an applicator be allowed to walk through drifting spray.” [4]

This textbook cited studies that suggested that dermal and respiratory exposure to paraquat did not appear to be a hazard to field applicators, despite the demonstration of absorption, as long as precautions against overexposure are taken.[5] The premise of the textbook discussion, that appropriate, well-known safety measures and protective gear are employed, was an important part of its analysis.

This early textbook discussion also flagged delayed lung fibrosis as the main problem caused by all modes of paraquat exposure, including dermal absorption:

“Although the acute symptoms of paraquat intoxication are of concern and are dangerous, the principal problem relates to the unique delayed manifestations of this chemical’s ability to produce a fibroblastic change in the lung which begins a number of days after absorption. * * * Experiments then found that it was possible to induce respiratory failure as a result of both dermal and aerosol routes of absorption (Newhouse, 1978).”[6]

An early review by the World Health Organization also emphasized that paraquat exposure was not expected to pose a health risk as long as safe work practices are followed:

“Occupational exposure to paraquat does not pose a health risk if the recommendations for use are followed and there is adherence to safe working practices.

                   *     *     *

In the small number of reported cases of paraquat poisoning allegedly resulting from occupational exposure, the cause can be identified as one or a combination of a number of factors, viz contamination of the skin with concentrated products, use of inadequately diluted solutions, use of faulty equipment, misuse of equipment (e.g., blowing blocked spray jets) or failure to take action in the event of contamination of skin or clothing.”[7]

Cases of dermal exposure to undiluted paraquat (20%), especially when exposure involved dermal exposure to the scrotum, can produce serious systematic toxicity.[8]

Ferebee was not given an appropriate respirator even when exposed to intense atmospheric contamination. He was drenched in paraquat spray, and remained drenched for hours. The gross negligence of his employer ensured that there would not be many similar cases, and that the tools of analytical epidemiology would not be available.[9] Indeed, epidemiology was never involved in determining general causation of paraquat exposure and lung fibrosis. Given that the outcome of interest would likely occur only in the context of negligent or intentional over-exposure, epidemiology will never be available.

Revisiting the Ferebee decision and the unique facts of the case place the decision in a better perspective for judging how courts continue to cite the case. The facts of the case readily distinguish the case, the claimed harm, and the manner of showing causation, from the facts in cancer, birth defects, and other cases where epidemiology is essential. The principle of charity would require the frequently quoted language on expert witness admissibility to be taken as a statement of the appellate standard of review for the jury’s determination of medical causation. Most of the glib characterizations of the Ferebee turn out to be wrong on close inspection of the case.

a. Ferebee was not a precedent under the Federal Rules of Evidence

Chevron’s evidentiary arguments were posed under Maryland law. Neither Rule 702[10] nor Rule 703[11] was ever mentioned in the district court or the Court of Appeals decisions.

b. Ferebee does not support a false distinction between scientific and legal causation.

In a later Bendectin birth defects case, Richardson v. Richardson-Merrell, Inc., the Court of Appeals struggled to distinguish Ferebee and its holdings based upon the ample epidemiologic evidence involving Bendectin. The Court mischaracterized Ferebee as not pertinent because it was on the “frontier of current medical and epidemiological inquiry.”[12] The Richardson court was impressed by the 20 years of research on Bendectin, including multiple epidemiologic studies. Unfortunately, the court was apparently ignorant of the irrelevance of epidemiology to the Ferebee case, and the extensive research base for determining the lung toxicity of paraquat. This ignorance seems to have resulted from Judge Mikva’s generalizations and overstatements of the paucity of evidence in Ferebee.

c. Ferebee does not support the false distinction between scientific and legal certainty.

Courts and commentators have attempted to explain the result in Ferebee by invoking what is largely a false distinction between scientific and legal certainty (or sufficiency). The Ferebee decision itself provided the ammunition by asserting a distinction between the requirements of scientific and legal decision making:

“In a courtroom, the test for allowing a plaintiff to recover in a tort suit of this type is not scientific certainly but legal sufficiency.”[13]

This was a common approach in distinguishing Ferebee, in the Bendectin litigation,[14] but it was picked up and promulgated by scientists and legal commentators.[15] Invoking this alleged distinction has become a common rhetorical move to excuse inadequate or insufficient evidence to support an expert witness’s causation opinion in litigation. The generalization from the facts of Ferebee to all scientific and legal questions of causation was wrong from the inception, and citations to a single case, Ferebee, cannot make those generalizations true.[16]

d. Ferebee did not establish the irrelevance or the dispensability of epidemiologic evidence in cancer or birth defects cases.

The Ferebee case observed that “a cause-effect relationship need not be clearly established by animal or epidemiological studies before a doctor can testify that in his opinion such a relationship exists.”[17] The bit about animal studies certainly cannot be part of the holding because the plaintiffs’ expert witnesses relied extensively on animal studies, along with human case reports, and human clinical studies of the metabolic fate and distribution of paraquat in both animals and humans.

The Ferebee case does properly stand for the proposition that there is a subset of all health effect cases for which epidemiologic evidence is unavailable and unnecessary for an expert witness to have for a valid conclusion of general and specific causation. The case illustrates how the ill effects of paraquat were observed shortly after exposure, and were sufficiently unique to not have a meaningful base- or background- rate. Adding the studies of absorption, metabolic fate and distribution, and mechanism of action, the plaintiff’s expert witnesses had an ample scientific, and legal, basis to assess causality. 

The Ferebee case is sometimes mistakenly thought of as a cancer case, which would have required epidemiologic evidence.[18] This mistake may well result from later courts citing Ferebee in cancer cases, for the proposition that epidemiologic evidence is unnecessary to support plaintiff’s causal claim between some exposure and some cancer. Perhaps the Illinois Supreme Court has provided the most egregious example of this sort of mistake. In Donaldson, a case involving plaintiff’s exposure to coal tar and his later development of neuroblastoma, the Court confusedly found Ferebee to be “of particular significance.”[19] The Donaldson court affirmed the trial court’s admission of plaintiffs’ expert witness testimony about “a causal link causal link despite the lack of a statistical number of others with neuroblastoma and a history of coal tar exposure.”[20] The court rambled on about how the plaintiffs were not required to prove general or specific causation “with 100% certainty that neuroblastoma.” This assertion was a common strawman argument that channels a misreading of Ferebee. The defense in Donaldson did not argue that 100% certainty was required, and such a level of posterior probability has never been required in law or in science.

The Ferebee case also did not establish that statistical significance was not required in epidemiologic studies for expert witnesses to be able reasonably to rely upon such studies. Because epidemiologic evidence was not at issue, there was no holding about epidemiologic studies or statistical significance as a criterion of the validity of such studies.

e. Ferebee did not establish that a clinician can opine about causation without sufficient facts and data.

One of plaintiff’s expert witnesses in Ferebee was Dr. Crystal, who was both a physician and a research scientist. His opinion as an expert witness was hardly without supporting facts and data, and the facts and data were of the exact kind that led to the scientific acceptance of the causal connection between some paraquat exposures and lung fibrosis. Crystal’s opinion was certainly not proffered without any evidentiary basis, as some have suggested.[21] Nor was Ferebee a case in which expert witnesses opined without facts and data to support unprecedented opinions on general and specific causation.[22]

This overwrought, over-extended interpretation of Ferebee as permitting causation opinions based upon only clinical observations of the patient appeared in the first edition of the Reference Manual on Scientific Evidence, but disappeared in all subsequent editions. In the chapter by evidence law professor Margaret Berger, the Manual reported that Ferebee was frequently cited for a “holding that causation can be established by the testimony of treating physicians.”[23] Berger’s observation about frequent citation is correct, but the observation does nothing to validate the opinion cited. Berger offered no comments or analysis in critique of the frequent miscitation of Ferebee, leaving the reader to believe that citing Ferebee for the sufficiency of treating physician opinion without data was somehow appropriate. The citations to which Berger referred were erroneous in 1994, and they remain erroneous today.


[1] Matrixx Iniatives, Inc. v. Siracusano, 563 U.S. 27, 131 S.Ct. 1309, 1320 (2011).

[2] Brief for the United States as Amicus Curiae, in Matrixx Iniatives, Inc. v. Siracusano, No. 09-1156, 2010 WL 4624148, at *15 (Nov. 2010).

[3] See, e.g., Benkwith v. Matrixx Initiatives, Inc., 467 F. Supp. 2d 1316, 1326, 1330, 1332 (M.D. Ala. 2006) (granting defendant’s motion to exclude testimony of an expert in the field of epidemiology regarding Zicam nasal spray’s causing plaintiff’s anosmia, because the opinions had not been tested and a rate of error could not be provided).

[4] Sheldon L. Wagner, CLINICAL TOXICOLOGY OF AGRICULTURAL CHEMICALS 198, 199-200 (1983).

[5] Id. at 200 (citing “[s]tudies by Staiff and co-workers (1975)” on occupationally exposed persons).

[6] Id. at 201. See also A. J. Gardiner, Pulmonary oedema in paraquat poisoning, 27 THORAX 132 (1972).

[7] WORLD HEALTH ORGANIZATION, ENVIRONMENTAL HEALTH CRITERIA 39: PARAQUAT AND DIQUAT at § 1.1.5. Effects on man (1984).

[8] See K. Tungsanga, S. Chusilp, S. Iarasena & V. Sitprija, Paraquat poisoning: evidence of systemic toxicity after dermal exposure, 59 POSTGRAD. MED. J. 338, 338 (1983).

[9] Cf. Zuchowicz v. United States, 140 F.3d 381 (2nd Cir. 1998) (analyzing causation in the context of defendants clear negligence that resulted in undisputed overexposure to prescription medication Danocrine). Unlike Zuchowicz, however, the Ferebee case did provide a strong evidentiary base for causation.

[10] See Kenneth J. Chesebro, Taking Daubert’s “Focus” Seriously: The Methodology/Conclusion Distinction, 15 CARDOZO L. REV. 1745, 1747, 1753 (1994) (misciting Ferebee as a Rule 702 case).

[11] See Alani Golanski, Judicial Scrutiny of Expert Testimony in Environmental Tort Litigation, 9 PACE ENVT’L L. REV. 399, 406-07 (1992) (misrepresenting Ferebee as a case under Rule 703; “this evidentiary issue was resolved through examination of the facts or data underlying the proffered expert opinion only to the extent necessary to make a Rule 703 determination on whether they are of the type reasonably relied upon by experts in the field.”). See also Michael C. McCarthy, “Helpful” or “Reasonably Reliable”? Analyzing the Expert Witness’s Methodology Under Federal Rules of Evidence 702 and 703, 77 CORNELL L. REV. 350, 373 (1992) (discussing Ferebee as a Rule 702 and 703 decision).

[12] Richardson v. Richardson-Merrell, Inc., 857 F.2d 823, 831-832 (D.C. Cir. 1988).

[13] Ferebee, 736 F.2d at 1536.

[14] Id.

[15] Louis Lasagna & Sheila R. Shulman, Bendectin and the Language of Causation, chap. 5, at 111, in Kenneth R. Foster, David E. Bernstein & Peter W. Huber, eds., PHANTOM RISK: SCIENTIFIC INFERENCE AND THE LAW (1993)

[16] See Michael C. McCarthy, “Helpful” or “Reasonably Reliable”? Analyzing the Expert Witness’s Methodology Under Federal Rules of Evidence 702 and 703, 77 CORNELL L. REV. 350, 373 (1992) (“Essentially, the Ferebee decision distinguished between the level of certainty required by a scientific discipline-and the level of certainty required by a court in drawing conclusions regarding causation”: and “Ferebee stands for the proposition that courts, in determining whether a given substance more likely than not caused a plaintiff’s injury, cannot always wait for the sciences.”).

[17] Ferebee, 736 F.2d 1529, 1535 (D.C. Cir. 1984).

[18] David E. Bernstein, The Misbegotten Judicial Resistance to the Daubert Revolution, 89 NOTRE DAME L. REV. 27, 36 (2013); David E. Bernstein, Expert Witnesses, Adversarial Bias, and the (Partial) Failure of the Daubert Revolution, 93 IOWA L. REV. 451, 465 (2008) (“Ferebee involved a claim that exposure to an herbicide caused an individuals’ cancer.”).

[19] Donaldson v. Central Illinois Public Service Co., 313 Ill. App.3d 1061, 730 N.E.2d 68, 79 (2000).

[20] Id.

[21] Lee Loevinger, Evidentiary Framework Margaret A. Berger Reference Manual on Scientific Evidence, 36 JURIMETRICS J. 149, 153 & n.21 (1996) (discussing the before (Daubert) times when “mere qualification and the facial relevance of an opinion might suffice to let an expert testify in some jurisdictions.”).

[22] See Kenneth J. Chesebro, Taking Daubert’s “Focus: Seriously: The Methodology/Conclusion Distinction, 15 CARDOZO L. REV. 1745, 1747 & n.20 (1994) (incorrectly arguing that Ferebee involved an expert witness offered an “unprecedented expert factual conclusion which no published literature supported.”

[23] See Margaret A. Berger, Evidentiary Framework, 39, 81 & n.164, in FEDERAL JUDICIAL CENTER, REFERENCE MANUAL ON SCIENTIFIC EVIDENCE (1st ed. 1994).

The Recrudescence of Ferebee – Part One

June 29th, 2026

The infamous Ferebee decision is certainly a contender to be a Dred Scott decision involving scientific evidence,[1] by declaring that science has no validity issues that the law is bound to respect.[2] The decision is often cited for its dictum, written with impressive rhetorical flourish, about how courts should not interfere with expert witness opinion testimony. The dictum, when written in 1984, was contrary to the law of Federal Rule of Evidence 702, and was relegated in 1993 to the trash bin of jurisprudential history by the Supreme Court’s 1993 decision in Daubert.[3]

Since 1993, scofflaw judges continued to cite Ferebee’s discredited dictum, without looking at the specific facts of the case. Indeed, even after Rule 702 was amended to clarify its meaning, courts have cited Ferebee as precedential for a let-it-all-in approach to expert witness testimony. As recently as February 2026, the Chief Judge of the Federal Circuit, of the United States Court of Appeals, cited Ferebee in derogation of Federal Rule of Evidence 702.[4] This recrudenscence of Ferebee warrants revisiting the case, what was actually decided, and whether it has any continuing jurisprudential relevance.

The Ferebee case was a personal injury case against the manufacturer of paraquat, a herbicide, for damages for severe pulmonary fibrosis. Interestingly, the case is sometimes erroneously cited as a cancer causation case, which may explain why some commentators criticize its dismissal of epidemiology and statistical significance.

Critics of Ferebee, as well as its acolytes, rarely describe the factual context of the case. The facts of a case are always germane to its holding, and Ferebee cannot be cited appropriately without a sane appreciation of its facts.

  1. Ferebee is a government negligence case.

The plaintiff worked for the federal government when he was exposed to paraquat. Richard Ferebee began working for the Department of Agriculture’s Beltsville Agricultural Research Center (BARC), in Beltsville, Maryland. He started spraying paraquat in the summer of 1977, and used the herbicide regularly through the time he was diagnosed with pulmonary fibrosis, in November 1979.[5] Mr. Ferebee sued Chevron Chemical Company, the supplier of the paraquat, for failing to warn. The important failure to warn, however, was committed by the federal governmental, which had actual knowledge of the hazard, and which owned the BARC facility, employed Ferebee, controlled and supervised his use of paraquat, and failed to comply with Chevron’s instructions. The federal government itself further regulated the sale and use of paraquat extensively, first by the Department of Agriculture, and later by the Environmental Protection Agency. [6]

  1. The exposure.

Ferebee filed his lawsuit in 1981; he died in 1982. His case was tried twice. In the first trial, the jury deadlocked. In the second trial, the jury returned a verdict in favor of his estate, and for his family, for $60,000. In his deposition testimony, Ferebee described how he sprayed paraquat, in the summer of 1977. The chemical was diluted for use, per Chevron’s instructions. There was no evidence that Ferebee ever had direct contact with undiluted paraquat, or that the paraquat he was exposed to was not diluted according to the proportions recommended on Chevron’s label.[7]

Crediting Ferebee’s testimony, the federal government was at best grossly negligent; at worst, the government was an intentional tortfeasor. In flagrant disregard of Chevron’s written instructions (as required by federal regulation), Ferebee frequently had the chemical on his ungloved hands.[8] Ferebee further described an occasion when he was drenched with paraquat as he walked behind a tractor that was spraying the chemical, and another incident when he used a defective sprayer that leaked paraquat “all over his pants.”[9]

On the occasions of Ferebee’s being exposed to paraquat without appropriate protective gear, the federal government deviated from its employer common law, statutory, and regulatory duties. Ferebee did not wash when he was dermally exposed to paraquat, and he went home contaminated, where he fell asleep, tired and dizzy, without showering.[10]  The exposure that Ferebee described would not have occurred had his federal employer followed the instructions on the label that the government itself mandated. In 1978, the federal Occupational Health & Safety Administration published Guidelines on the need for protective clothing, respirators, immediate washing of contaminated skin. Ferebee’s federal governmental employer recklessly disregarded the guidelines it mandated that Chevron provide.

  1. The warnings.

Paraquat could be sold in the United States only when labeled in accordance with EPA regulations, promulgated pursuant to the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA).[11] The statute bars EPA from allowing sale of regulated herbicides, such as paraquat, unless the chemicals, as labeled, will not cause “unreasonable adverse effects on the environment.”[12] Such effects are in turn defined as any unreasonable risk to man or the environment, taking into account the economic, social, and environmental costs and benefits of the use of [the] pesticide.[13] FIFRA further requires the EPA to require labeling that is “adequate to protect health and the environment” and that is “likely to be read and understood.”[14]

In the Ferebee case, both the district and the circuit courts failed to provide the complete warning label and the material data safety sheets that Chevron supplied to the federal government employer, as required by the federal government. There are “snippets” of the warning communications in the published opinions, which make clear that the government was largely if not entirely to blame for failing to comply with the directions required under FIFRA. For instance, the district court, in a footnote, acknowledged:

“For example, the label advised the user spraying paraquat to wear waterproof clothing and goggles, to avoid working in spray mist, and to wash splashes on the skin or eyes immediately with water.”[15]

The Court of Appeals Ferebee opinion described the label,[16] as stating a warning in large bold letters:

DANGER

CAN KILL IF SWALLOWED

HARMFUL TO THE EYES AND SKIN

The label also informed users to wash any exposed areas immediately, and to remove contaminated clothing.[17]

  1. The Stipulation.

Essential to understanding the holding in Ferebee are the facts of the case, including the parties’ stipulation:

“that Mr. Ferebee’s only significant exposure to paraquat was on his intact skin; i.e., there was no evidence that Mr. Ferebee swallowed or inhaled paraquat, or that he spilled or sprayed it on an area of his skin upon which he had any apparent cuts or scrapes. The jury was not, of course, precluded from concluding that a person engaged in Mr. Ferebee’s line of work could have had some, or even many, minor cuts or abrasions not readily discernible to the naked eye or likely to be remembered some time later.”[18]

Why did the plaintiffs try to present their case solely as a dermal exposure cases? As we will see, this stratagem made their medical causation case a little more difficult, but it avoided defenses of serious misuse and lack of proximate cause. Ferebee had been instructed by his co-workers and supervisors that paraquat was extremely dangerous if swallowed or inhaled. The warning label was unequivocal in detailing the dangers and the need to avoid ingestion. (Without the full label, it is difficult to evaluate how well the label warned against inhalation, but the 1978 OSHA guidelines address the use of a proper respirator for situations in which paraquat may be inhaled.) On the other hand, the label had a weakness, which could be exploited, as long as the preemption defense could be held at bay: the label urged protective clothing, goggles, and immediate washing of contaminated skin, but it failed to describe the consequence of dermal exposure other than irritation. Ferebee could thus try to avoid his own culpable conduct, as well as a sophisticated intermediary defense, by claiming that his exposure was only dermal.

Why did Chevron agree to the stipulation? Ferebee surely had some inhalational exposure when he walking behind applicators and when he was drenched in paraquat. The Chevron warning label, per government-employer regulations, did not specify respirator usage for ordinary work exposures of applicators (as opposed to workers who handled undiluted paraquat, or who worked in confined spaces). The defendant probably felt sanguine about its preemption defense, and thus also about the adequacy of its warnings overall. The stipulation limited the plaintiff’s medical causation case to a route of exposure that put it into an arguable “first instance” case report. Chevron stood to gain a claim of “lack of notice,” and thus lack of actual or constructive knowledge of the risk of lung disease from dilute dermal exposure. The clinical presentation itself differed from many of the cases of known paraquat poisoning, and Chevron probably believed that it could deal with the medical causation claim better if exposure was limited to transdermal absorption on unbroken skin.

  1. Medical causation

Chevron stridently argued that there had been no previous documented cases of pulmonary fibrosis in workers exposed to diluted paraquat on unbroken skin. The manufacturer’s argument was clever by halves.  The following facts were uncontroverted as known at the time of Chevron’s sale of the product:

  • Paraquat causes pulmonary fibrosis in humans.
  • The evidence that established paraquat as a cause of pulmonary fibrosis was largely case series of acute onset of pulmonary fibrosis after ingestion.
  • Paraquat induces pulmonary fibrosis relatively rapidly.
  • Paraquat can be absorbed through the skin.
  • The parties agreed that any type of exposure – ingestion, inhalation, or dermal absorption – could cause lung damage.[19]
  • Once paraquat is ingested, inhaled, or absorbed, it can travel to the lungs.
  • Lung fibrosis caused by dermal absorption of paraquat had been described previously only with skin lesions before or after the injury.[20]
  • The lungs are the target organ for paraquat, regardless of route of administration.
  • There are numerous causes of pulmonary fibrosis (such as asbestosis, scleroderma, rheumatoid arthritis, etc.).
  • The variants of pulmonary fibrosis do not all look alike clinically or pathologically, present alike, or progress alike.
  • Ferebee had no known other disease or exposure that could account for his pulmonary fibrosis.
  • There are cases of pulmonary fibrosis with no identifiable cause, known as idiopathic pulmonary fibrosis (IPF).
  • IPF is relatively rare; it too has a rapid onset and progression, although arguably not as fast as the cases described after exposure to undiluted paraquat.
  • Ferebee’s medical history was largely unhelpful in explaining his clinical course.
  • Ferebee had some shortness of breath before starting to use paraquat.[21]
  • Ferebee used or was exposed to paraquat occasionally over three years before he was diagnosed with pulmonary fibrosis.

These stipulated facts are rarely acknowledged in the discussion of the Ferebee case. The legal implications of these facts are far reaching. General causation in a sense was not contested. Paraquat causes pulmonary fibrosis. The issue was whether diluted paraquat through dermal exposure over three years causes pulmonary fibrosis, and whether this exposure caused Ferebee’s pulmonary fibrosis. Chevron stridently asserted that the “scientific method” required controlled experimental or observational (epidemiologic) studies. The problem with Chevron’s position was that general causation had already been established, and not by analytical epidemiologic studies. General causation between paraquat exposure of any kind and pulmonary fibrosis had been established by case reports, based upon close temporal proximity between exposure and pulmonary toxicity and fibrosis. Animal toxicology and mechanistic studies confirmed the toxicity observed in clinical studies.[22]

Because idiopathic pulmonary fibrosis is rare, the appearance of this disease in a series of exposed workers soon after they were exposed to a specific toxic chemical really did not require the rigors of analytical epidemiology. The causal analysis between paraquat and lung fibrosis was more akin to the analysis that is used to attribute liver failure to herbal exposure than the epidemiologic approach to the relationship between smoking and lung cancer. At the time of Ferebee’s exposure and his litigation, there was no serious dispute that paraquat caused pulmonary fibrosis when inhaled or swallowed, or that paraquat was absorbed dermally, or that the lung was a target organ of paraquat exposure of any sort.

  1. The expert witnesses.

Ferebee was initially treated by Dr. Muhammed Yusuf, a pulmonary specialist, who diagnosed pulmonary fibrosis. Dr. Yusef referred Ferebee to the National Institutes of Health (NIH), where he came under the care of Dr. Ronald G. Crystal of the Heart, Lung, and Blood Institute. (Dr. Crystal is now Chairman of Genetic Medicine at Weill-Cornell Medical College, where he continues to practice pulmonary medicine.)

In the litigation, Chevron called Dr. Carrington, who diagnosed Ferebee with idiopathic pulmonary fibrosis. Dr. Carrington challenged the plaintiffs’ expert witnesses’ opinions for lacking reliance upon controlled observational or experimental studies.[23] Dr. Carrington, however, acknowledged that dermal cases are too rare for observational epidemiologic analysis, but emphasized that no animal studies of sufficient size had been done to support plaintiffs’ hypothesis. Chevron also called a Dr. Fisher, who presented a toxicokinetic (TK) analysis of Ferebee’s dermal absorption. Based upon his TK analysis, Dr. Fisher concluded that the maximal amount of paraquat absorbed by Ferebee was too small, based upon known cases and animal studies, to have caused paraquat toxicity with lung fibrosis.[24]

  1. Chevron’s challenge to plaintiffs’ expert witnesses’ causation opinion.

None of the defendant’s expert witnesses examined Ferebee. The courts thought this was relevant, but the judicial opinions never articulated what would have been observed on physical examination that was important to resolving the differential diagnosis of paraquat toxicity versus IPF. There was no dispute that Ferebee had rapidly progressing pulmonary fibrosis. The expert witnesses on both sides evaluated Ferebee’s clinical data, presentation, clinical course, and arrived at different diagnoses, either paraquat-induced lung fibrosis or IPF. The plaintiffs’ expert witnesses’ diagnosis involved a causal attribution to paraquat exposure; the defendant’s expert witness’s diagnosis of IPF ruled out any causal toxic exposure.

The Ferebee case was litigated under Maryland law because federal statutory law requires state law to control in a wrongful death action arising out of the neglect or wrongful act of another on a federal enclave.[25] The choice of law had implications both for procedural and substantive law. Chevron appears to have relied upon Maryland’s articulation of the Frye general acceptance doctrine, and the courts analyzed Chevron’s arguments as a Frye challenge.[26] Under the Erie doctrine, a federal court should have applied its own procedural law to the case at hand, including Rule 702 of the Federal Rules of Evidence.[27] The use of Maryland law to determine an evidentiary issue in federal court was error.

Chevron pressed its challenge in terms of Maryland’s version of Frye, and not under Federal Rule of Evidence 702. The oft-repeated infamous language used by both the district and the circuit courts was, therefore, not an interpretation of federal law. Rule 702 was never cited or discussed in either the trial or the appellate court’s opinion. This oddity has profound implications for how we evaluate the Ferebee decision, and how it can be cited. Before the Supreme Court decided the Daubert case, the epistemic implications of Rule 702 were largely ignored. Defendants sometimes attempted to press the Frye twilight-zone general acceptance test into a rule of decision that would reject an expert witness’s opinion testimony.[28] The Frye case was decided by a federal appellate court, but superseded by the enactment of Rule 702, in 1975. Ferebee was, of course, decided before the Supreme Court breathed life into Rule 702, but Rule 702 was nonetheless the law when the Ferebee case was litigated.

  1. The judicial resolution of  Chevron’s Frye challenge

The district court insightfully recognized that Chevron was demanding a level of evidence, which had never been required to establish paraquat’s generally accepted ability to cause pulmonary fibrosis. This recognition led to the district court’s rhetorical language:

“It is true that medical expert testimony must be grounded in proper scientific methodology, but the extremely stringent standard that defendant suggests is beyond reason. Product liability law, especially as it relates to relatively new products or those with a relatively rare yet significant danger, would be rendered next to meaningless if a plaintiff could prove he was injured by a product only after a ‘statistically significant’ number of other people were also injured. A civilized legal system does not require that much human sacrifice before it can intervene. The fact that this is the first case of this exact type – or at least the first of its exact type in which the involvement of paraquat was discovered by alert doctors – cannot be enough by itself to shield defendant from liability. Defendant’s experts were not able to fault Dr. Crystal for his basic diagnostic methodology; in fact, they used the same kinds of test results, consultations, and other tools that he did. What they disagreed with chiefly were his conclusions.”[29]

The important observation is that general causation had been established case series and reports of human exposure. There never was statistical evidence that had been evaluated for “significance,” to establish general causation for undiluted paraquat, and the trial court refused, under Maryland law, to require such evidence for general causation for diluted paraquat. In this context, we can see that the trial court’s suggestion that statistical significance was not required has little bearing upon cases in which general causation could only be established using epidemiologic evidence, with its attendant statistical inferences.

Of course, the matter only became worse when Chevron persisted in its argument and presented it to a panel of the D.C. Circuit. The litigants pulled a panel of what can be described as activist judges not known for their scientific acumen. Judge Mikva wrote the opinion for a panel that included Judge Wald, and Senior Judge Bazelon. The panel’s decision ratcheted up the district court’s rhetoric:

“Thus, a cause-effect relationship need not be clearly established by animal or epidemiological studies before a doctor can testify that, in his opinion, such a relationship exists. As long as the basic methodology employed to reach such a conclusion is sound, such as use of tissue samples, standard tests, and patient examination, product liability does not preclude recovery until a ‘statistically significant’ number of people have been injured or until science has had the time and resources to complete sophisticated laboratory studies of the chemical. In a courtroom, the test for allowing a plaintiff to recover is not scientific certainty, but legal sufficiency; if reasonable jurors could conclude from the expert testimony that paraquat more likely than not caused Ferebee’s injury, the fact that another jury might reach the opposite conclusion or that science would require more evidence before conclusively considering the causation question resolved is irrelevant. That Ferebee’s case may have been the first of its exact type, or that his doctors may have been the first alert enough to recognize such a case, does not mean that the testimony of those doctors, who are concededly well qualified in their fields, should not have been admitted.”[30]

Judge Mikva’s dichotomy between levels of certainty needed in science and in the law was false. On behalf of the plaintiff, Dr. Crystal had done much more than give a clinical diagnosis. His assessment of causality was informed by case series of exposure and lung fibrosis, along with physiological evidence of oral, inhalational, and dermal absorption and distribution to the lungs, with toxic effect soon after exposure.

The appellate court’s dismissive attitude towards statistically significant evidence is severely limited to the factual context of a causal analysis that had been made by scientists, to everyone’s satisfaction, for undiluted paraquat, without the need for epidemiologic, statistical evidence. Statistical significance was never really at issue. In this way, Ferebee resembles the untoward dictum on statistical significance from Matrixx Initiatives Inc. v. Siracusano,[31] where the Court held that causation was not at issue.

In Ferebee, causation was very much at issue, but it had been well established – and the subject of warnings – based upon clinical case reports of paraquat exposure and rapid development of lung fibrosis. Dermal absorption and systemic distribution with toxic effects in the lungs were well established, and not the stuff of epidemiologic proofs.

In both Ferebee and Matrixx Initiatives, statistical significance was never really at issue. In Ferebee, there was no statistical evidence needed or used to reach causal conclusions about paraquat’s ability to induce pulmonary fibrosis. In Matrixx Initiatives, allegations of statistical significance and causation were not necessary because the plaintiffs needed only to allege materiality of the facts suppressed by the company in order to plead a securities fraud case. The FDA could impose warnings or require a product recall on evidence that fell well short of establishing causality. Materiality thus could be established without causation, and neither causation nor statistical significance needed to be alleged.

As for Chevron’s Frye challenge, the district court rejected the implied call for a vote on the general acceptance of Dr. Crystal’s reasoning. Frye may require “vote counting” of some sort, but the process becomes irrelevant when virtually no one has registered to vote. Otherwise, both the defense and plaintiffs’ expert witnesses were indeed using the same technique of arguing by analogy to accepted cases of paraquat poisoning or IPF. Dr. Crystal opined that Ferebee’s case was “similar” to three other cases he had identified. Dr. Carrington argued that Ferebee’s case was more like IPF cases, although IPF cases themselves have some clinical heterogeneity as well. Most reported paraquat cases described onset of toxicity to death as a very rapid process. Ferebee did not present with significant symptoms for three years after his first exposure, and then he survived for another two plus years. Ferebee did not report skin lesions, which had been reported in previous cases of dermal exposure leading up to pulmonary fibrosis. On the other hand, there was no precise exposure assessment for Ferebee’s absorption of paraquat. The case presented, on the diagnostic level, with the implied causality, a difficult call, but it is easy to understand the courts’ impatience with the defendant’s insistence upon more stringent criteria and evidence than was used to establish the causal connection with undiluted paraquat. The ability of paraquat to cause pulmonary fibrosis had been well established based upon case reports, including case reports of dermal exposure to open sores, with documented systemic distribution with specific toxicity to the lung, regardless of the route of administration.

  1. Expert witness qualifications.

Chevron never challenged Dr. Yusuf’s or Dr. Crystal’s qualifications, both of whom were highly accomplished and respected clinicians and scientists. Neither was a “hired gun.” The oft-quoted comments about expert witness qualifications were made in the context of describing the appellate court’s standard of review, and the court’s role in not assessing credibility or weighing the evidence:

“These admonitions apply with special force in the context of the present action, in which an admittedly dangerous chemical is alleged through long-term exposure to have caused disease. Judges, both trial and appellate, have no special competence to resolve the complex and refractory causal issues raised by the attempt to link low-level exposure to toxic chemicals with human disease. On questions such as these, which stand at the frontier of current medical and epidemiological inquiry, if experts are willing to testify that such a link exists, it is for the jury to decide whether to credit such testimony.”[32]

Remarkably, this language has been mistakenly invoked as a standard for trial courts to use in determining the admissibility of expert witness opinion testimony. It is no such thing. Some other observations are in order. Although Ferebee worked with diluted paraquat, his exposures were hardly low level. He described himself as drenched in the herbicide, without protective gear, and without his governmental supervisors ever directing him to shower and change clothing.

  1. Preemption and Warnings Causation.

Ultimately, Chevron’s preemption defense was rejected by both the district and the circuit court. The defense’s claim of FIFRA preemption might have gone very differently today, after the Supreme Court’s decisive application of preemption to FIFRA labeling of glyphosate.[33]

Even more important in evaluating liability is the emphasis that both the district and the appellate courts gave to the important role of the employer in the case. The evidence showed that there was indeed a warning label that Ferebee had never read. The plaintiff’s case was thus in jeopardy of failing to show proximate causation between an allegedly inadequate warning and harm. The courts, however, emphasized the role that the employer, through its supervisors and responsible co-workers, play in the complex organizational situation of a modern workplace:

“Mr. Ferebee’s situation was quite different, however. He did not purchase paraquat for his personal use; rather, it was provided to him by his employer for use on the job. The evidence showed that his principal source of information about paraquat was the oral instructions of his supervisors and co-workers, not the written label. He learned from them how to mix the product and how to spray it. It was also from this source that he learned of the danger of getting the product in his mouth: one of his co-workers warned him that if he accidently swallowed paraquat, it would ‘get in his blood’ and poison him. This is a common pattern of instruction and use of occupational materials in the workplace. Learning by doing and learning by oral instruction are tried and true methods of educating manual workers in their jobs. Therefore, although it is crucial to plaintiff’s case that someone would have read the label, it was not necessary for Mr. Ferebee to have done so. And it is obvious that one or more employees at BARC did read the label, since information did reach Mr. Ferebee about the proportions for diluting the product and about the dangers about which the label did warn. It was appropriate for the jury to infer that a warning about the danger of fatal lung disease from dermal exposure would also have been communicated to Mr. Ferebee. See Restatement (Second) of Torts § 388 comment n (seller normally entitled to assume that adequate warning will be passed on by purchaser to ultimate user); cf. Chambers v. G.D. Searle & Co., 441 F.Supp. at 381 (in product liability case involving prescription drug, relevant warning is the one given to doctor, not patient).”[34]

There is significant irony in that the Ferebee case has been the subject of serious criticism from defense counsel, and yet it embraced Section 388, comment n, as well as applied the learned or sophisticated intermediary principles to a case not involving prescription drugs. The appellate court waxed enthusiastic about the principles of Section 388, and went so far as to cite the late Victor Schwartz in support:

“We live in an organizational society in which traditional common-law limitations on an actor’s duty must give way to the realities of society. *** In this case, Mr. Ferebee did not purchase the paraquat for his personal use, and there was substantial evidence that workplace communication about the dangers associated with various chemicals usually took the form of oral instructions from supervisors to workers, the latter of whom then retransmitted the information to co-workers. This, rather than individual reading of product warnings, is a typical method by which information is disseminated in the modern workplace. See Schwartz & Driver, “Warnings in the Workplace: The Need for a Synthesis of Law and Communication Theory,” 52 U. Cinn. L. Rev. 38, 66-83 (1983). The requirement that an improper warning proximately ‘cause’ the injury should be elaborated against this background. We believe Maryland would construe its tort law in this case to require only that someone in the workplace have read the label, not that Mr. Ferebee personally have read it. Because there is no dispute that one or more employees at BARC did read the label, we hold that the jury could properly have inferred that, had a warning about the danger of disease from dermal exposure been included on the label, that warning would have been communicated to Mr. Ferebee and that he would as a result have acted differently. Alternatively, the jury could have inferred that an adequate warning would have led Ferebee’s employers to undertake steps that would have protected him from paraquat poisoning-for example, provision of showers for use after spraying.”[35]

Judge Mikva’s prediction, of course, was accurate; Maryland tort law did, soon thereafter, embrace the sophisticated intermediary defense to exculpate the defendant in such remote supplier situations.[36] The principle invoked to excuse plaintiff from reading the warning label also works to exculpate the defendant when that warning label is otherwise adequate, or when the intermediary knows of the hazard in any event. Given that the employer was the federal government, including the scientists at EPA, OSHA, the National Institutes of Health, and the Public Health Service, as well as the plaintiff’s principal expert witness (Dr. Crystal), the employer had complete and superior knowledge to the seller about the known or knowable effects of diluted paraquat.[37]


[1]  Nathan Schachtman, Wells v. Ortho Pharmaceutical Corporation -A Dred Scott Case in Science Jurisprudence, ResearchGate (June 2026); DOI: 10.13140/RG.2.2.30242.18880

[2] Ferebee v. Chevron Chem. Co., 552 F. Supp. 1297 (D.D.C. 1982), aff’d, 736 F.2d 529 (D.C. Cir.), cert. denied, 469 U.S. 1062 (1984).

[3] Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579 (1993).

[4] Willis Electric Co., Ltd. v. Polygroup Ltd., 166 F. 4th 1363, 1379, 1380-81 (Fed. Cir. 2026) (citing Ferebee, and declaring that the validity of assumptions underlying an expert witness’s methodology were fact questions for the jury, and not a a proper basis for excluding the challenged expert witness testimony). See also Barry v. DePuy Synthes Cos., 164 F.4th 896, 912 (Fed. Cir. 2026) (characterizing expert witness challenges to “purported flaws” in methodology as objections that “go to the weight the jury might accord to that evidence and not to its admissibility.”)

[5] Ferebee, 736 F.2d at 1531-32.

[6] Id. at 1532.

[7] 552 F. Supp. at 1295 & n. 3.

[8] Ferebee, 552 F. Supp. at 1294-95

[9] Ferebee, 736 F.2d at 1532.

[10] Id.

[11] 7 U.S.C. § 136, et seq.

[12] 7 U.S.C. § 136a(c)(5)(C).

[13] 7 U.S.C. § 136(bb).

[14] 7 U.S.C. § 136(q)(1)(E). See Ferebee 736 F.2d at 1539-40.

[15] 552. F. Supp. at 1304 n.40.

[16] Ferebee, 736 F.2d at 1536.

[17] Id.

[18] 552. F. Supp. at 1295 & n. 3.

[19] Ferebee, 552. F. Supp. at 1300 & n.28.

[20] Ferebee, 736 F.2d at 1538.

[21] Ferebee, 552. F. Supp. at 1295.

[22] See generally Leah Utyasheva, Prabath Amarasinghe & Michael Eddleston, Paraquat at 63 – the story of a controversial herbicide and its regulations: It is time  to put people and public health first when regulating paraquat, 25 BMC PUB. HEALTH 3089 (2025).

[23]  Ferebee, 552. F. Supp. at 1301.

[24] Id.

[25] 16 U.S.C. § 457; Ferebee, 736 F.2d at 1533.

[26] Ferebee, 552 F. Supp. at 1301; 736 F.2d at 1535.

[27] Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579, 589 & n.6 (1993). See also Cavallo v. Star Enterprise, 100 F.3d 1150, 1157-58 (4th Cir. 1996); Amorgianos v. National Railroad Passenger Corp., 303 F.3d 256 (2d Cir. 2002); Legg v. Chopra, 286 F.3d 286, 289-92 (6th Cir. 2002). See Erie R.R. Co. v. Tompkins, 304 U.S. 64 (1938); Hanna v. Plumer, 380 U.S. 460, 470 (1965) (Erie does not displace the application of federal procedural rules in federal courts).

[28] Frye v. United States, 293 F. 1013, 1014 (D.C.Cir.1923).

[29] Ferebee, 552 F. Supp. at 1301.

[30] Ferebee, 736 F.2d at 1535-36 (emphasis in original).

[31] 563 U.S. 27 (2011). See Nathan Schachtman & David Venderbush, Matrixx Unbounded:  High Court’s Ruling Needlessly Complicates Scientific Evidence Principles, 26(4) WASH. LEG. FDTN. LEG. BACKGROUNDER (2011).

[32] Ferebee, 736 F.2d at 1534.

[33] Monsanto v. Durnell, ___ U.S. ___, Slip op. (June 25, 2026), available at https://www.supremecourt.gov/opinions/25pdf/24-1068_n7ip.pdf

[34] Ferebee, 552 F. Supp. at 1303-04 (internal citations omitted).

[35] Ferebee, 736 F.2d at 1539 (emphasis in original; internal citation omitted).

[36] See, e.g., Kennedy v. Mobay Corp., 84 Md. App. 397 (1990) (applying sophisticated user defense to bar claims against manufacturers of toluene diisocyanate), aff’d, 325 Md. 385 (1992); Higgins v. E.I. DuPont de Nemours, Inc., 671 F. Supp. 1055 (D. Md. 1987) (Maryland law; holding that manufacturer of paint was in better position than bulk supplier to communicate warnings to customers’ employees), aff’d, 863 F.2d 1162 (4th Cir. 1988).

[37] See Miller v. Diamond Shamrock Co., 275 F.3d 414, 422-23 (5th Cir. 2001) (“There can be no reasonable dispute that knowledge possessed by the United States Public Health Service, … [and] the Navy’s Bureau of Medicine and Surgery is the knowledge of the military.”).

The FDA Expert Panel on Talc – More Malarky     

June 18th, 2025

On May 20, 2025, as announced, FDA Commissioner Martin Makary held his panel discussion on talc in food and medications.[1] The discussion lasted just under two hours, and is available on YouTube for your viewing and perhaps your amusement. Makary opened and closed the event with what could have been the plaintiffs’ opening and closing statements from one of the many talc trials that have clouded courtrooms across the land. He asked rhetorically: “Why don’t we talk about at our oncology meetings the 1993 National Toxicology Program results that found clear evidence of carcinogenic activity of talc in animal studies?’” Perhaps because the talc findings were questionable at best, and the asbestos findings with respect to gastrointestinal cancers were exculpatory for talc.

Makary’s introductory remarks were followed by the panelists’ introducing themselves by their training and involvement with talc issues. Other than Makary, the participants were FDA Deputy Commissioner Sara Brenner, George Tidmarsh, John Joseph Godleski, Sandra McDonald, Daniel Cramer, Joellen Schildkraut, Malcolm Sim, Steven Pfeiffer, Nicolas Wentzensen, and Nicole C. Kleinstreuer. Godleski and Cramer have served as plaintiffs’ expert witnesses in ovarian cancer litigation, which was not particularly germane to the panel discussion. In their initial discussions of qualifications and background, neither Godleski nor Cramer disclosed his potential conflicts of interest, or the amount of fees earned. Sandra McDonald described her experience in assisting Godleski, but she did not declare whether she earned any money for consulting services to the lawsuit industry. Later in the panel discussion, when George Tidmarsh stated that no one should be vilified for past practices in using talc, Daniel Cramer jumped in to vilify Johnson & Johnson with the suggestion that somehow that company had surreptitiously arranged for the National Cancer Institute to remove a statement about how talc “may be associated with talc use” from its website just before he was about to testify in his first talc trial for plaintiffs.

None of the panelists had served as a defense expert witness. Steven Pfeiffer works for a pharmaceutical company, but not one that had any experience with the safety or efficacy of talc as an ingredient in medications.

None of the panelists had participated in any toxicologic or epidemiologic study of talc on cancers or diseases of the digestive organs. None of the panelists made it his or her business to become familiar with the extensive studies of the asbestos and talc on gastrointestinal cancers. The lack of experience, or specific citations to any study, did not stop Daniel Cramer from suggesting that talc was responsible for inflammatory bowel disease, autoimmune diseases, and gastrointestinal cancers.  Like Cramer, epidemiologist Joellen Schildkraut, focused on ovarian cancer, and made the false assertion that the relationship between talc and gastrointestinal cancers is understudied. Schildkraut held back from asserting that talc causes ovarian cancer, but she heartily endorsed banning talc on the precautionary principle. All the panelists concurred with the suggestion that talc be eliminated from food and drugs, without waiting for “the epidemiologists to catch up.”

Two issues were grossly misrepresented by the panelists. None of them, however, was well informed enough for the misrepresentations to have been overt lies. The first whopper was that National Toxicology Program (NTP) testing had shown carcinogenicity of talc in its inhalational studies for the lung and other organs. The second whopper was that rice on talc was used prevalently in the United States, and that it was responsible for digestive organ cancers. Nicole C. Kleinstreuer, who has worked at the NTP, and accurately described its activities gave a description of its animal talc studies, perhaps a bit slanted, but not too inaccurate. When George Tidmarsh later misrepresented NTP talc findings, however, Kleinsteuer was silent.

NTP Ingestion Studies

Makary did not identify the NTP studies to which he referred, but Kleinsteuer described a talc inhalation study that has only one referent. The NTP conducted long-term rodent inhalation and ingestion assays for both talc and different kinds of asbestos, in the 1980s and 1990s. For talc, the NTP published, in 1993, only one long-term inhalational study in rats and mice.[2] In mice, exposed to talc by inhalation for up to two years, there was no evidence of any “neoplastic” effects. The results in rats were more difficult to interpret. In male rats, exposed for over two years, there was weak evidence of neoplastic effects based upon an increased incidence of benign or malignant adrenal gland pheochromocytomas. In female rats, the NTP reported “clear evidence” of excess alveolar/bronchiolar (lung) adenomas and carcinomas and benign or malignant adrenal gland pheochromocytomas of the adrenal gland. The meaning of these rodent studies obviously varies depending upon whether you are a rat or a mouse of a certain breed; the meaning for humans is even murkier, even for humans that are rodent-like. The multiple comparisons across exposure levels for dozens if not hundreds of outcomes, and the lumping of benign and malignant effects together, certainly makes the NTP statistical analyses suspect. This report was marked by significant controversy, and some scientists refused to endorse its finding because adrenal gland pheochromocytomas were not treatment-related; the maximum-tolerated dose was exceeded for female rats at the higher exposure level, thus violating the study’s protocol; and talc is thus not expected to cause tumors in rats (and mice) exposed at levels that do not cause “marked chronic lung toxicity.”[3]

One of the lawsuit industry’s, and Makary’s, theories about the harmfulness of ingested talc is based upon the supposition that talc has asbestos contaminants. This theory is as vague as is the term asbestos, which has no mineralogical meaning; instead, the term asbestos was historically used to refer to six different minerals: actinolite, anthophyllite, amosite (cummingtonite-grunerite), chrysotile, crocidolite, and tremolite. All of these minerals, except for chrysotile, are amphibole minerals. Some of the amphibole minerals occur in both fibrous and non-fibrous form, and the ill health effects of the amphibole fibers are generally attributed to their resistance to biological degradation and their high aspect ratio. Things get a bit crazy because the federal government, for purposes of standardizing aerosol measurements, set the aspect ratio for counting “fibers,” at 3:1. The pathogenicity of “federal fibers,” which are not really fibers, is highly disputed.

The NTP never conducted long-term talc ingestion studies; it did something much better. The NTP tested dietary high-dose, long-term ingestion of various asbestos types in multiple species. The NTP did not leave the exposure issue vague with “asbestos” as the dietary source. Instead, the NTP was more precise when testing whether ingesting “asbestos” was harmful to rodents. The NTP ran separate ingestion experiments on chrysotile, amosite, and crocidolite, with the different form of asbestos making up one percent of the animals’ lifetime diet. Overall, these experiments were “null”; that is, they provided no support for the carcinogenicity of ingested asbestos of the types tested.

The NTP conducted lifetime ingestion studies in male and female rats with a diet of one percent crocidolite asbestos, the most toxic and carcinogenic form of asbestos in human beings. The NTP experiments showed that under these conditions, long-term ingestion of crocidolite asbestos was neither overtly toxic nor carcinogenic in male or in female rats.[4] After crocidolite, amosite asbestos, fibrous cummingtonite-grunerite, named for “asbestos mines of South Africa, is the most toxic and carcinogenic of the asbestos fibers. The NTP showed that feeding male and female rats amosite asbestos for one percent of their diet, for their lifetimes, was not overtly toxic, did not affect their survival, and was not carcinogenic.[5] The NTP repeated its life-time one percent amosite diet in Syrian Golden hamsters, again without toxic or carcinogenic response in either the male or female hamsters.[6]

Looking at the least toxic and carcinogenic asbestos mineral, chrysotile, the NTP’s conducted long-term one percent feed studies of both “short range” and “long range” (chrysotile fiber length) in Syrian Golden hamsters. Again the results were “null”; that is, there was no treatment-related toxicity or carcinogenicity.[7] There were no increases in adrenal cortical adenomas (benign growths) when compared with concurrent controls, but there was an increase of these benign tumors when compared with pooled control groups from other experiments. Ultimately, the NTP concluded that the biological importance of these benign adrenal growths in the absence of cancers or tumors of the gastrointestinal tract (which was the target organ) was questionable, at best.

Because of prior research suggesting that carcinogencity was a function of fiber rigidity and length, the NTP tested ingested chrysotile in rats, at two different fiber lengths. For its experiments, the NTP defined “short-range chrysotile (SR)” as short fibers with a median length of 0.66 microns, and a range of 0.088 to 51.1 microns. “Intermediate-range (IR) chrysotile fibers had a median length of 0.82 microns, with a range from 0.104 to 783.4 microns. The NTP did not use long-range chrysotile fibers, which are generally greater than 5 microns in length. Male and female F344/N rats ingested an NTP one percent diet of chrysotile, in the two lengths of chrysotile, SR and IR, for a lifetime. There were no neoplastic or non-neoplastic diseases, overt toxicity, or decrease in survival associated with SR chrysotile ingestion, in either the male or the female rats.[8] In the female rats, there was no effect on fertility or litter, overt toxicity, or carcinogenicity from IR chrysotile ingestion. The male rats also did not show any adverse clinical signs, but they experienced a statistically insignificant increase in benign colonic polyps, which the NTP stretched to characterize as “some” (but not clear) evidence of carcinogenicity.

Rice is Nice, With or Without Talc

The FDA panelists’ inaccurate claims about talc on rice also cry out for rebuttal, which no panelist seemed able or willing to give. Given that the panel was convened with only four days notice, and without public comment, it operated in a fact-free zone, and operated mostly as a propaganda exercise. The history of the ingested asbestos and talc controversy goes back over half a century. Some background is needed to understand exactly how outlandish the rice-on-talc claim is.

The causal association between asbestosis and lung cancer was well established by the early 1960s,[9] as was the causal association between crocidolite asbestos exposure and mesothelioma.[10] Some sources carelessly credit Irving Selikoff with these discoveries, but he was not so much of a discoverer, as he was a zealous spokesman for the safety of asbestos-exposed workers. Selikoff worked hand-in-hand with various labor unions to publicize and politicize asbestos risks that had been shown by other workers. Credit for the lung cancer connection properly goes to earlier work done by Sir Richard Doll and others, and the crocidolite-mesothelioma connection was shown by J. Christopher Wagner, in 1960. Where Selikoff deserves credit is in tireless efforts to expand the scope of asbestos-related diseases beyond lung cancer and mesothelioma, with or without sufficient evidence, and thus to expand the compensability of other diseases of ordinary life in asbestos workers.

In his efforts to extend the scope of compensation, Selikoff did not limit himself to risks that had been scientifically established; he sought to expand the list of asbestos-related diseases. He advanced the unsubstantiated notions that all six kinds of asbestos minerals carried the same risks, that asbestos caused virtually every kind of cancer in humans, that any asbestos in the environment required extreme remedial action, and that asbestos was responsible for a very high percentage of all human cancers.

No doubt Selikoff wanted credit for scientific discoveries, but he also wanted science that would support compensation. Selikoff understood that if the asbestos workers stopped smoking, their risks of lung cancer would fall, and their cancer morbidity and mortality would be more influenced by gastrointestinal cancers, given that colorectal cancer was the leading cause of cancer-related death in non-smoking men, in the 1960s.

By 1950, Selikoff had already become an advocate, who testified and wrote reports as a claimants’ expert witness in many asbestos cases. In the early 1950s, New Jersey lawyer Carl Gelman retained Selikoff to examine 17 workers from the Paterson plant of Union Asbestos and Rubber Company (UNARCO). Gelman filed workers’ compensation claims on behalf of these UNARCO workers, and Selikoff supported Gelman’s claims with reports and testimony. In the early 1950s, Anton Szczesniak, one of the UNARCO claimants, with Selikoff’s support as an expert witness, sought compensation for “intestinal cancer.” In 1965, Selikoff testified to support an asbestos insulator’s claim that asbestos exposure caused his colorectal cancer.[11] In 1974, Selikoff wrote a review article on asbestos exposure and gastrointestinal cancers, without any disclosure of his pro-plaintiff testimonial adventures.[12] Serious epidemiologists such as Sir Richard Doll and Sir Richard Peto pushed back on Selikoff’s exaggerated projections of asbestos-related mortality,[13] and his assertion that asbestos caused digestive system cancers.[14] Forty years after Selikoff testified for the claimant in an asbestos colorectal cancer case, the Institute of Medicine published a systematic review of the evidence available to Selikoff and later evidence, which showed that the evidence was insufficient “to infer a causal relationship between asbestos exposure and pharyngeal, stomach, and colorectal cancers.”[15]

Selikoff’s rent-seeking and fear-mongering spawned many asbestos scares. Some scientists accepted Selikoff’s dogma that a single asbestos fiber, of any variety, could cause any human cancer. The Mt. Sinai jihad against “asbestos” extended to any exposures involving asbestos, or even other minerals that contained “elongated mineral particles,” that nominally met the crude definition of asbestos. This jihad led to a prolonged litigation against the Reserve Mining Company, which had permits to dump taconite tailings in Lake Superior, since the late 1940s. Using Selikoff’s claim that “asbestiform” mineral particles had entered the water supply, the U.S. Environmental Protection Agency was able to obtain an injunction against the mining company.[16]

Regulatory overreach, Selikoff’s exaggerated testimony, and the trial judge’s partiality and bias marred the litigation.[17] After decades of research on asbestos in drinking water, there remains no substantial evidence that supports a conclusion that ingested asbestos in drinking water causes gastrointestinal or any other cancer.[18]

Selikoff was the head of an anti-asbestos lobby that promoted the fiction that asbestos was responsible for all manners of human ailments, regardless of dose or route of administration.[19] One of the panics he helped initiate involved the claim that talc-dusted rice was responsible for the high rate of stomach cancer among Japanese in Japan.

Reuben Merliss published an article in Science, in 1971, in which he attempted to attribute the high rate of stomach cancer in Japan to the Japanese custom of dusting rice with talc. Merliss relied upon overall population rates and trends to draw an ecologic inference that the Japanese rice (with talc and any asbestos contaminants) was responsible for the Japanese higher incidence of stomach cancer.[20]

The Merliss hypothesis, inspired by Selikoff, was sunk by a much more careful analysis (which got less media coverage). Two epidemiologists analyzed data about use of talc-coated rice in Japan and Hawaii, and found no support for the claim that talc-coated rice increased the risk of developing stomach cancer.[21]

Their more careful dietary assessment found high rates of stomach cancer among Japanese in Japan who did not consume talc-coated rice, while Japanese in Hawaii, who consumed considerable quantities of talc-coated rice had intermediate rates of stomach cancer (lower than in Japan). Filipinos in Hawai had very low rates of gastric cancer, even though they consumed the greatest amounts of talc-coated rice of any of the observed groups. The secular incidence trend of stomach cancer decreased more substantially among the talc-exposed Japanese living in Hawaii than among the non-exposed Japanese living in Japan.

Although the asbestos perpetual motion litigation machine continues to churn, the lawsuit industry has been hampered by the bankruptcy of virtually every company that made an asbestos-containing product, and the reduction of asbestos use and exposures over the last 50 years. The lawsuit industry’s shift to demonize and monetize talc as the next mineral target was predictable. What was not predictable was that we would have a Secretary of Health & Human Services whose sole experience in medicine has been in suing pharmaceutical and other manufacturing industries, perpetuating medieval beliefs in the miasma theory of disease causation,[22] and spreading conspiracies, misinformation, and disinformation. FDA Commissioner Makary has shown himself to be a willing accomplice in advancing the Secretary’s agenda. In his closing remarks, Makary made unsupported assertions, then retreated to the dodge that he was just asking questions. Makary strongly suggested that the recent increase in colorectal cancer among young people has been caused by the use of talc in food and medications. He failed to reference any evidence for his suggestion, which is, in any event, hard to square with the history of use of talc in medications for centuries, and the steady overall decline in the incidence of colorectal cancer in men and women.[23]

The Center for Truth in Science has sponsored rigorous systematic reviews of the evidence on cosmetic talc use and female reproductive cancers,[24] and respiratory cancers.[25] The systematic review of talc on reproductive organ cancers integrated evidence across toxicologic and epidemiologic studies, and found suggestive evidence of no association between the use of perineal talc and ovarian and endometrial cancers. The systematic review of talc use and respiratory cancers similarly integrated the available toxicologic and epistemiologic evidence, and rejected a causal association. The review reached a conclusion of suggestive evidence in the opposite direction – of no association between inhaled talc and mesothelioma or lung cancer.

The FDA talc panel was fool’s gold, and not the promised “gold standard” science. Rather than engaging with the systematic reviews sponsored by the Center, or for that matter with any systematic reviews, Commissioner Makary and his panel wallowed in anecdotes, stories, and isolated study results, without trying to identify and synthesize all the available evidence.


[1] FDA Expert Panel on Talc, “Independent Expert Panel to Evaluate Safety and Necessity of Talc in Food, Drug, and Cosmetic Products,” FDA (May 20, 2025).

[2] NTP Technical Report on the Toxicology and Carcinogenesis Studies of Talc (CAS No. 14807-96-6) in F344/N Rats and B6C3F Mice (Sept. 1993).

[3] Jay I. Goodman, “An Analysis of the National Toxicology Program’s (NTP) Technical Report (NTP TR 421) on the Toxicology and Carcinogenesis Studies of Talc,” 21 Regulatory Toxicol. & Pharmacology 244 (1995). See also Robyn L. Prueitt, Nicholas L. Drury, Ross A. Shore, Denali N. Boon & Julie E. Goodman, “Talc and human cancer: a systematic review of the experimental animal and mechanistic evidence,”  54 Critical Reviews in Toxicology  359 (2024).

[4] NTP TR-280 Toxicology and Carcinogenesis Studies of Crocidolite Asbestos (CASRN 12001-28-4) In F344/N Rats (Feed Studies) (1988).

[5] NTP TR-279 Toxicology and Carcinogenesis Studies of Amosite Asbestos (CASRN 12172-73-5) in F344/N Rats (Feed Studies) (1990).

[6] NTP TR-249 Lifetime Carcinogenesis Studies of Amosite Asbestos (CASRN 12172-73-5) in Syrian Golden Hamsters (Feed Studies) (1983).

[7] NTP TR-246 Lifetime Carcinogenesis Studies of Chrysotile Asbestos (CASRN 12001-29-5) in Syrian Golden Hamsters (Feed Studies) (1990).

[8] NTP – TR-295 Toxicology and Carcinogenesis Studies of Chrysotile Asbestos (CASRN 12001-29-5) in F344/N Rats (Feed Studies) (1985).

[9] See Richard Doll, “Mortality from Lung Cancer in Asbestos Workers,”  12 Br. J. Indus. Med. 81 (1955).

[10] See J. Christopher Wagner, C.A. Sleggs, and Paul Marchand, “Diffuse pleural mesothelioma and asbestos exposure in the North Western Cape Province,” 17 Br. J. Indus. Med. 260 (1960); J. Christopher Wagner, “The discovery of the association between blue asbestos and mesotheliomas and the aftermath,” 48 Br. J. Indus. Med. 399 (1991).

[11] See “Health Hazard Progress Notes,”16 The Asbestos Worker 13 (May 1966) (“A recent decision has widened the range of compensable diseases for insulation workers even further. A member of Local No. 12. Unfortunately died of a cancer of the colon. Dr. Selikoff reported to the compensation court that his research showed that these cancers of the intestine were at least three times as common among the insulation workers as in men of the same age in the general population. Based upon Dr. Selikoff’s testimony, the Referee gave the family a compensation award, holding that the exposure to many dusts during employment was responsible for the cancer. The insurance company appealed this decision. A special panel of the Workman’s Compensation Board reviewed the matter and agreed with the Referee’s judgment and affirmed the compensation award. This was the first case in which a cancer of the colon was established as compensable and it is likely that this case will become an historical precedent.”).

[12] Irving J. Selikoff, “Epidemiology of Gastrointestinal Cancer,” 9 Envt’l Health Persp. 299 (1974).

[13] Richard Doll & Richard Peto, “The causes of cancer: quantitative estimates of avoidable risks of cancer in the United States today,” 66 J. Nat’l Cancer Instit. 1191 (1981).

[14] Richard Doll and Julian Peto, Asbestos: Effects on Health of Exposure to Asbestos 8 (1985).

[15] Jonathan M. Samet, et al., Asbestos: Selected Cancers – Institute of Medicine (2006).

[16] See Wendy Wriston Adamson, Saving Lake Superior: A Story of environmental action (1974); Frank D. Schaumburg, Judgment Reserved: A Landmark Environmental Case (1976); Robert V. Bartlett, The Reserve Mining Controversy: Science, Technology, and Environmental Quality (1980); Thomas F. Bastow, This Vast Pollution: United States of America v. Reserve Mining Company (1986); Michael E. Berndt & William C. Brice, “The origins of public concern with taconite and human health: Reserve Mining and the asbestos case,” 52 Regulatory Toxicol. & Pharmacol. S31 (2008).

[17] Reserve Mining Co. v. Lord, 529 F.2d 181 (8th Cir. 1976) (removing Judge Lord from case).

[18] See World Health Organization, Asbestos in Drinking Water (4th ed. 2021) (“no causal association between asbestos exposure via drinking-water and cancer development has been reported for any asbestos fibre type”); Jennifer Go, Nawal Farhat, Karen Leingartner, Elvin Iscan Insel, Franco Momoli, Richard Carrier & Daniel Krewski, “Review of epidemiological and toxicological studies on health effects from ingestion of asbestos in drinking water,” 54 Critical Reviews in Toxicology 856 (2024) (“Based on high-quality animal studies, an increased risk for cancer or non-cancer endpoints was not supported, aligning with findings from human studies. Overall, the currently available body of evidence is insufficient to establish a clear link between asbestos contamination in drinking water and adverse health effects.”); Kenneth D. MacRae, “Asbestos in drinking water and cancer,” 22 J. Royal Coll. Physicians 7 (1988).

[19] Francis Douglas Kelly Liddell, “Magic, Menace, Myth and Malice,” 41 Ann. Occup. Hyg. 3, 3 (1997) (“[A]n anti-asbestos lobby, based in the Mount Sinai School of Medicine of the City University of New York, promoted the fiction that asbestos was an all-pervading menace, and trumped up a number of asbestos myths for widespread dissemination, through media eager for bad news.”).

[20] Rueben R. Merliss, “Talc-Treated Rice and Japanese Stomach Cancer,” 173 Science 1141 (1971). The claim persists in the underworld of medical speculation. See E. Whitin Kiritani, “Asbestos and Stomach Cancer in Japan – A Connection?” 33 Medical Hypotheses 159 (1990).

[21] Grant N. Stemmermann & Lawrence N. Kolonel, “Talc-coated rice as a risk factor for stomach cancer,” 31 Am. J. Clin. Nutrition 2017 (1978).

[22] Paul Offit, “Understanding RFK Jr.,” Beyond the Noise (Feb. 11, 2025).

[23] American Cancer Society, “Key Statistics for Colorectal Cancer” (last revised April 28, 2025).

[24] Heather N. Lynch, Daniel J. Lauer, Olivia Messina Leleck, Rachel D. Freid, Justin Collins, Kathleen Chen, William J. Thompson, A. Michael Ierardi, Ania Urban, Paolo Boffetta & Kenneth A. Mundt, “Systematic review of the association between talc and female reproductive tract cancers,” 5 Front. Toxicol. 1157761 (2023).

[25] Heather N. Lynch, Daniel J. Lauer, William J. Thompson, Olivia Leleck, Rachel D. Freid, Justin Collins, Kathleen Chen, A. Michael Ierardi, Ania M. Urban, Michael A. Cappello, Paolo Boffetta & Kenneth A. Mundt, “Systematic review of the scientific evidence of the pulmonary carcinogenicity of talc,” 10 Front. Public Health 989111 (2022).

800 Plaintiffs Fail to Show that Glyphosate Caused Their NHL

September 11th, 2024

Last week, Barbara Billauer, at the American Council on Science and Health[1] website, reported on the Australian court that found insufficient scientific evidence to support plaintiffs’ claims that they had developed non-Hodgkin’s lymphoma (NHL) from their exposure to Monsanto’s glyphosate product. The judgment had previously been reported by the Genetic Literacy Project,[2] which republished an Australian news report from July.[3] European news media seemed more astute in reporting the judgment, with The Guardian[4] and Reuters reporting the court decision in July.[5] The judgment was noteworthy because the mainstream and legal media in the United States generally ignored the development.  The Old Gray Lady and the WaPo in the United States, both of which have covered previous glyphosate cases in the United States, sayeth naught. Crickets at Law360.

On July 24, 2024, Justice Michael Lee, for the Federal Court of Australia, ruled that there was insufficient evidence to support the claims of 800 plaintiffs that their NHL had been caused by glyphosate exposure.[6] Because plaintiffs’ claims were aggregated in a class, the judgment against the class of 800 or so claimants, was the most significant judgment in glyphosate litigation to date.

Justice Lee’s opinion is over 300 pages long, and I have had a chance only to skim it. Regardless of how the Australian court handled various issues, one thing is indisputable: the court has given a written record of its decision processes for the world to assess, critique, validate, or refute. Jury trials provide no similar opportunity to evaluate the reasoning processes (vel non) of the decision maker. The absence of transparency, and an opportunity to evaluate the soundness of verdicts in complex medical causation, raises the question whether jury trials really satisfy the legal due process requirements of civil adjudication.


[1] Barbara Pfeffer Billauer, “The RoundUp Judge Who Got It,” ACSH (Aug. 29, 2024).

[2] Kristian Silva, “Insufficient evidence that glyphosate causes cancer: Australian court tosses 800-person class action lawsuit,” ABC News (Australia) (July 26, 2024).

[3] Kristian Silva, “Major class action thrown out as Federal Court finds insufficient evidence to prove weedkiller Roundup causes cancer,” ABC Australian News (July 25, 2024).

[4] Australian Associated Press, “Australian judge dismisses class action claiming Roundup causes cancer,” The Guardian (July 25, 2024).

[5] Peter Hobson and Alasdair Pal, “Australian judge dismisses lawsuit claiming Bayer weedkiller causes blood cancer,” Reuters (July 25, 2024).

[6] McNickle v. Huntsman Chem. Co. Australia Pty Ltd (Initial Trial) [2024] FCA 807.

The Proper Study of Mankind

December 24th, 2023

“Know then thyself, presume not God to scan;

The proper study of Mankind is Man.”[1]

 

Kristen Ranges recently earned her law degree from the University of Miami School of Law, and her doctorate in Environmental Science and Policy, from the University of Miami Rosenstiel School of Marine, Atmospheric, and Earth Science. Ranges’ dissertation was titled Animals Aiding Justice: The Deepwater Horizon Oil Spill and Ensuing Neurobehavioral Impacts as a Case Study for Using Animal Models in Toxic Tort Litigation – A Dissertation.[2] At first blush, Ranges would seem to be a credible interlocutor in the never-ending dispute over the role of whole animal toxicology (and in vitro toxicology) in determining human causation in tort litigation. Her dissertation title is, however, as Martin Short would say, a bit of a tell. Zebrafish become sad when exposed to oil spills, as do we all.

Ranges recently published a spin-off of her dissertation as a law review article with one of her professors. “Vermin of Proof: Arguments for the Admissibility of Animal Model Studies as Proof of Causation in Toxic Tort Litigation.”[3] Arguments for; no arguments against. We can thus understand this is an advocacy piece, which is fair enough. The paper was not designed or titled to mislead anyone into thinking it would be a consideration of arguments for and against extrapolation from (non-human) animal studies to human beings. Perhaps you will think it churlish of me to point out that animal studies will rarely be admissible as evidence. They come into consideration in legal cases only through expert witnesses’ reliance upon them. So the issue is not whether animal studies are admissible, but rather whether expert witness opinion testimony that relies solely or excessively on animal studies for purposes of inferring causation is admissible under the relevant evidentiary rules. Talking about the admissibility of animal model studies signals, if nothing else, a serious lack of familiarity with the relevant evidentiary rules.

Ranges’ law review is clearly, and without subtlety, an advocacy piece. She argues:

“However, judges, scholars, and other legal professionals are skeptical of the use of animal studies because of scientific and legal concerns, which range from interspecies disparities to prejudice of juries. These concerns are either unfounded or exaggerated. Animal model studies can be both reliable and relevant in toxic tort cases. Given the Federal Rules of Evidence, case law relevant to scientific evidence, and one of the goals of tort law-justice-judges should more readily admit these types of studies as evidence to help plaintiffs meet the burden of proof in toxic tort litigation.”[4]

For those of you who labor in this vineyard, I would suggest you read Ranges’ article and judge for yourself. What I see is a serious lack of scientific evidence for her claims, and a serious misunderstanding of the relevant law. One might, for starters, putting aside the Agency’s epistemic dilution, ask whether there are any I.A.R.C. category I (“known”) carcinogens based solely upon animal evidence. Or has the U.S. Food & Drug Administration ever approved a medication as reasonably safe and effective based upon only animal studies?

Every dog owner and lover has likely been told by a veterinarian, or the Humane Society, that we should resist their lupine entreaties and withhold chocolate, raisins, walnuts, avocados, and certain other human foods. Despite their obvious intelligence, capacity for affection, when it comes to toxicology, dogs are not people, although some people act like the less reputable varieties of dogs.

Back in 1985, in connection with Agent Orange litigation, the late Judge Jack Weinstein wrote what was correct then, and even more so today, that “laboratory animal studies are generally viewed with more suspicion than epidemiological studies, because they require making the assumption that chemicals behave similarly in different species.”[5] Judge Weinstein was no push-over for strident defense counsel or expert witnesses, but the legal consequences were nonetheless obvious to him, when he looked carefully at the animal studies plaintiffs’ expert witnesses were claiming to support their opinions. “[A]nimal studies are of so little probative value as to be inadmissible.  They cannot be a predicate for an opinion under Rule 703.”[6] One of the several disconnects between the plaintiffs’ expert witnesses’ animal studies and the human diseases claimed was the disparity of dose and duration between the relied upon studies and the service men claimants. Judge Weinstein observed that when the hand waving stopped, “[t]here is no evidence that plaintiffs were exposed to the far higher concentrations involved in both animal and industrial exposure studies.”[7]

Ranges and Oakley unfairly deprecate the Supreme Court’s treatment of animal evidence in the 1997 Joiner opinion.[8] Mr. Joiner had been an electrician by a small city in Georgia, where he experienced dermal exposure, over several years, to polychlorinated biphenyls (PCB’s), a chemical found in electrical transformer coolant. He alleged that he had developed small-cell lung cancer from his occasional occupational exposure. In the district court, a careful judge excluded the plaintiffs’ expert witnesses, who relied heavily upon animal studies and who cherry picked and distorted the available epidemiology.[9] The Court of Appeals reversed, in an unsigned, non-substantive opinion that interjected an asymmetric standard of review.[10]

After granting review, the Supreme Court engaged with the substantive validity issues passed over by the intermediate appellate court. In addressing the plaintiff’s expert witnesses’s reliance upon animal studies, the Court was struck by an extrapolation from a different species, different route of administration, different dose, different duration of exposure, and different disease.[11] Joiner was an adult human whose alleged exposure to PCBs was far less than the exposure in the baby mice that received injections of PCBs in a high concentration. The mice developed alveologenic adenomas, a rare tumor that is usually benign, not malignant.[12] The Joiner Court recognized that these multiple extrapolations were a bridge to nowhere, and reversed the Court of Appeals, and reinstated the judgment of the district court. What is particular salient about the Joiner decision, and about which you will find no discussion in the law review paper by Ranges and Oakley, is how well the Joiner opinion has held up over quarter of a century that passed. Today, in the waning moments of 2023, there is still no valid, scientifically sound support for the claim that the sort of exposure Mr. Joiner had can cause small-cell lung cancer.[13]

Perhaps the most egregious lapses in scholarship occur when Ranges, a newly minted scientist, and her co-author, a full professor of law, write:

“For example, Bendectin, an antinausea medication prescribed to pregnant women, caused a slew of birth defects (hence its nickname ‘The Second Thalidomide’).49[14]

I had to re-read this sentence many times to make sure I was not hallucinating. Ranges’ and Oakley’s statement is, of course, demonstrably false. A double whooper, at least, and a jarring deviation from the standard of scholarly care.

But their statement is footnoted you say. Here is what the cited article, footnote 40 in “Vermin of Proof,” says:

“RESULTS: The temporal trends in prevalence rates for specific birth defects examined from 1970 through 1992 did not show changes that reflected the cessation of Bendectin use over the 1980–84 period. Further, the NVP hospitalization rate doubled when Bendectin use ceased.

CONCLUSIONS: The population results of the ecological analyses complement the person-specific results of the epidemiological analyses in finding no evidence of a teratogenic effect from the use of Bendectin.”[15]

So the cited source actually says the exact opposite of what the authors assert. Apparently, students on law review at Georgetown University Law Center do not check citations for accuracy. Not only was the statement wrong in 1993, when the Supreme Court decided the famous Daubert case, it was wrong 20 years later, in 2013, when the United States Food and Drug Administration (FDA) approved  Diclegis, a combination of doxylamine succinate and pyridoxine hydrochloride, the essential ingredients in Bendectin, for sale in the United States, for pregnant women experiencing nausea and vomiting.[16] The return of Bendectin to the market, although under a different name, was nothing less than a triumph of science over the will of the lawsuit industry.[17] 

Channeling the likes of plaintiffs’ expert witness Carl Cranor (whom they cite liberally and credulously), Ranges and Oakley argue for a vague “weight of the evidence” (WOE) methodology, in which several inconclusive and lighter-than-air pieces of evidence somehow magically combine in cold fusion to warrant a conclusion of causation. Others have gone down this dubious path before, but these authors’ embrace of the plaintiffs’ expert witnesses’ opinion in Bendectin litigation reveals the insubstantiality and the invalidity of their method.[18] As Professor Ronald Allen put the matter:

“Given the weight of evidence in favor of Bendectin’s safety, it seems peculiar to argue for mosaic evidence [WOE] from a case in which it would have plainly been misleading.”[19]

It surely seems like a reduction ad absurdum of the proposed methodology.

One thing these authors get right is that most courts disparage and exclude expert witness opinion that relies exclusively or excessively upon animal toxicology.[20] They wrongly chastise these courts, however, for ignoring scientific opinion. In 2005, the Teratology Society issued a position paper on causation in teratology-related litigation,[21] in which the Society specifically addressed the authors’ claims:

“6. Human data are required for conclusions that there is a causal relationship between an exposure and an outcome in humans. Experimental animal data are commonly and appropriately used in establishing regulatory exposure limits and are useful in addressing biologic plausibility and mechanism questions, but are not by themselves sufficient to establish causation in a lawsuit. In vitro data may be helpful in exploring mechanisms of toxicity but are not by themselves evidence of causation.”[22]

Ranges and Oakley are flummoxed that courts exclude expert witnesses who have relied upon animal studies when regulatory agencies use such studies with abandon. The case law on the distinction between precautionary standards in regulation and causation standards in tort law is clear, and explains the difference in approach, but these authors are determined to ignore the obvious difference.[23] The Teratology Society emphasized what should be hornbook law; namely, regulatory standards for testing and warnings are not particularly germane to tort law standards for causation:

“2. The determination of causation in a lawsuit is not the same as a regulatory determination of a protective level of exposure. If a government agency has determined a regulatory exposure level for a chemical, the existence of that level is not evidence that the chemical produces toxicity in humans at that level or any other level. Regulatory levels use default assumptions that are improper in lawsuits. One such assumption is that humans will be as sensitive to the toxicity of a chemical as is the most sensitive experimental animal species. This assumption may be very useful in regulation but is not evidence that exposure to that chemical caused an adverse outcome in an individual plaintiff. Regulatory levels often incorporate uncertainty factors or margins of exposure. These factors may result in a regulatory level much lower than an exposure level shown to be harmful in any organism and are an additional reason for the lack of utility of regulatory levels in causation considerations.”[24]

The suggestion from Ranges and Oakley that the judicial treatment of reliance upon animal studies is based upon ossified, ancient precedent, prejudice, and uncritical acceptance of defense counsel’s unsupported argument is simply wrong. There are numerous discussions of the difficulty of extrapolating teratogenicity from animal data to humans,[25] and ample basis for criticism of the glib extension of rodent carcinogenicity to humans.[26]

Ranges and Oakley ignore the extensive scientific literature questioning extrapolation from high exposure rodent models to much lower exposures in humans.[27] The invalidity of extrapolation can result in both false positives and false negatives. Indeed the thalidomide case is a compelling example of the failure of animal testing. Thalidomide was tested on pregnant rats and rabbits without detecting teratogenicity; indeed most animal species do not metabolize thalidomide or exhibit teratogenicity as seen in humans. Animal models simply do not have a sufficient positive predictive value to justify a conclusion of causation in humans, even if we accept a precautionary principle recognition of such animal testing for regulatory purposes.[28]

As improvident as Ranges’ pronouncements may be, finding her message amplified by Professor Ed Cheng on his podcast series, Excited Utterances, was even more disturbing. In November 2023, Cheng interviewed Kristen Ranges in an episode of his podcast, Vermin of Proof, in which he gave Ranges a chance to reprise her complaints about the judiciary’s handling of animal evidence, without much in the way of specificity, and with some credulous cheerleading to aid and abet. In his epilogue, Cheng wondered why toxicologic evidence is disfavored when such evidence is routinely used by scientists and regulators. What Cheng misses is that regulators use toxicologic evidence for regulation, not for assessments of human causation, and that the two enterprises are quite different.  The regulatory exercise goes something like asking about the stall speed of a pig. It does not matter that pigs cannot fly; we skip that fact and press on to ask what the pig’s take off and stall speeds are.

Seventy years ago, no less than Sir Austin Bradford Hill, observed that:

“We may subject mice, or other laboratory animals, to such an atmosphere of tobacco smoke that they can — like the old man in the fairy story — neither sleep nor slumber; they can neither breed nor eat. And lung cancers may or may not develop to a significant degree. What then? We may have thus strengthened the evidence, we may even have narrowed the search, but we must, I believe, invariably return to man for the final proof or proofs.”[29]


[1] Alexander Pope, “An Essay on Man” (1733), in Robin Sowerby, ed., Alexander Pope: Selected Poetry and Prose at 153 (1988).

[2] Kristen Ranges, Animals Aiding Justice: The Deepwater Horizon Oil Spill and Ensuing Neurobehavioral Impacts as a Case Study for Using Animal Models in Toxic Tort Litigation – A Dissertation (2023).

[3] Kristen Ranges & Jessica Owley, “Vermin of Proof: Arguments for the Admissibility of Animal Model Studies as Proof of Causation in Toxic Tort Litigation,” 34 Georgetown Envt’l L. Rev. 303 (2022) [Vermin]

[4] Vermin at 303.

[5] In re Agent Orange Prod. Liab. Litig., 611 F. Supp. 1223, 1241 (E.D.N.Y. 1985), aff’d, 818 F.2d 187 (2d Cir. 1987), cert. denied, 487 U.S. 1234 (1988).

[6] Id.

[7] Id.

[8] General Elec. Co. v. Joiner, 522 U.S. 136, 144 (1997) [Joiner]

[9] Joiner v. General Electric Co., 864 F. Supp. 1310 (N.D. Ga. 1994).

[10] Joiner v. General Electric Co., 134 F.3d 1457 (11th Cir. 1998) (per curiam). 

[11] Joiner, 522 U.S. at 144-45.

[12] See Leonid Roshkovan, Jeffrey C. Thompson, Sharyn I. Katz, Charuhas Deshpande, Taylor Jenkins, Anna K. Nowak, Rosyln Francis, Carole Dennie, Dominique Fabre, Sunil Singhal, and Maya Galperin-Aizenberg, “Alveolar adenoma of the lung: multidisciplinary case discussion and review of the literature,” 12 J. Thoracic Dis. 6847 (2020).

[13] See How Have Important Rule 702 Holdings Held Up With Time?” (Mar. 20, 2015); “The Joiner Finale” (Mar. 23, 2015).

[14] Vermain at 312.

[15] Jeffrey S Kutcher, Arnold Engle, Jacqueline Firth & Steven H. Lamm, “Bendectin and Birth Defects II: Ecological Analyses, 67 Birth Defects Research Part A: Clinical and Molecular Teratology 88, 88 (2003).

[16] See FDA News Release, “FDA approves Diclegis for pregnant women experiencing nausea and vomiting,” (April 8, 2013).

[17] See Gideon Koren, “The Return to the USA of the Doxylamine-Pyridoxine Delayed Release Combination (Diclegis®) for Morning Sickness — A New Morning for American Women,” 20 J. Popul. Ther. Clin. Pharmacol. e161 (2013).

[18] Michael D. Green, “Pessimism About Milward,” 3 Wake Forest J. Law & Policy41, 62-63 (2013); Susan Haack, “Irreconcilable Differences? The Troubled Marriage of Science and Law,” 72 Law & Contemporary Problems 1, 17 (2009); Susan Haack, “Proving Causation: The Holism of Warrant and the Atomism of Daubertm” 4 J. Health & Biomedical Law 273, 274-78 (2008).

[19] Ronald J. Allen & Esfand Nafisi, “Daubert and its Discontents,” 76 Brooklyn L. Rev. 132, 148 (2010). 

[20] See In re Zoloft (Sertraline Hydrochloride) Prods. Liab. Litig., 26 F. Supp. 3d 466, 475 (E.D. Pa. 2014) (noting that “causation opinions based primarily upon in vitro and live animal studies are unreliable and do not meet the Daubert standard.”), aff’d, 858 F.3d 787 (3rd Cir. 2017); Chapman v. Procter & Gamble Distrib., LLC, 766 F.3d 1296, 1308 (11th Cir. 2014) (affirming exclusion of testimony based on “secondary methodologies,” including animal studies, which offer “insufficient proof of general causation.”); The Sugar Ass’n v. McNeil-PPC, Inc., 2008 WL 11338092, *3 (C.D. Calif. July 21, 2008) (finding that plaintiffs’ expert witnesses, including Dr. Abou-Donia, failed to provide the requisite analytical  support for the extrapolation of their Five Opinions from rats to humans”); In re Silicone Gel Breast Implants Prods. Liab. Litig., 318 F. Supp. 2d 879, 891 (C.D. Cal. 2004) (observing that failure to compare similarities and differences across animals and humans could lead to the exclusion of opinion evidence); Cagle v. The Cooper Companies, 318 F. Supp. 2d 879, 891 (C.D. Calif. 2004) (citing Joiner, for observation that animal studies are not generally admissible when contrary epidemiologic studies are available; and detailing significant disadvantages in relying upon animal studies, such as (1) differences in absorption, distribution, and metabolism; (2) the unrealistic, non-physiological exposures used in animal studies; and (3) the use of unverified assumptions about dose-response); Wills v. Amerada Hess Corp., No. 98 CIV. 7126(RPP), 2002 WL 140542, at *12 (S.D.N.Y. Jan. 31, 2002) (faulting expert’s reliance on animal studies because there was no evidence plaintiff had injected suspected carcinogen in same manner as studied animals, or at same dosage levels), aff’d, 379 F.3d 32 (2nd Cir. 2004) (Sotomayor, J.); Bourne v. E.I. du Pont de Nemours & Co., 189 F. Supp. 2d 482, 501 (S.D. W.Va. 2002) (benlate and birth defects), aff’d, 85 F. App’x 964 (4th Cir.), cert. denied, 543 U.S. 917 (2004); Magistrini v. One Hour Martinizing Dry Cleaning noted that “[a]nimal bioassays are of limited use in determining whether a particular chemical causes a particular disease, or type of cancer, in humans.”190 180 F. Supp. 2d 584, 593 (D.N.J. 2002); Soutiere v. BetzDearborn, Inc., No. 2:99-CV-299, 2002 WL  34381147, at *4 (D. Vt. July 24, 2002) (holding expert’s evidence inadmissible when “[a]t best there are animal studies that suggest a link between massive doses of [the substance in question] and the development of certain kinds of cancers, such that [the substance in question] is listed as a ‘suspected’ or ‘probable’ human carcinogen”); Glastetter v. Novartis Pharms. Corp., 252 F.3d 986, 991 (8th Cir. 2001); Hollander v. Sandoz Pharm. Corp., 95 F. Supp. 2d 1230, 1238 (W.D. Okla. 2000), aff’d, 289 F.3d 1193, 1209 (10th Cir. 2002) (rejecting the relevance of animal studies to causation arguments in the circumstances of the case); Allison v. McGhan Medical Corp., 184 F.3d 1300, 1313–14 (11th Cir.1999); Raynor v. Merrell Pharrns. Inc., 104 F.3d 1371, 1375-1377 (D.C. Cir.1997) (observing that animal studies are unreliable, especially when “sound epidemiological studies produce opposite results from non-epidemiological ones, the rate of error of the latter is likely to be quite high”); Lust v. Merrell Dow Pharms., Inc., 89 F.3d 594, 598 (9th Cir.1996); Barrett v. Atlantic Richfield Co., 95 F.3d 375 (5th Cir. 1996) (extrapolation from a rat study was speculation); Nat’l Bank of Comm. v. Dow Chem. Co., 965 F. Supp. 1490, 1527 (E.D. Ark. 1996) (“because of the difference in animal species, the methods and routes of administration of the suspect chemical agent, maternal metabolisms and other factors, animal studies, taken alone, are unreliable predictors of causation in humans”), aff’d, 133 F.3d 1132 (8th Cir. 1998); Hall v. Baxter Healthcare Corp., 947 F. Supp. 1387, 1410-11 (D. Or. 1996) (with the help of court-appointed technical advisors, observing that animal studies taken alone fail to predict human disease reliably); Daubert v. Merrell Dow Pharrns., Inc., 43 F.3d 1311, 1322 (9th Cir. 1995) (on remand from Supreme Court with directions to apply an epistemic standard derived from Rule 702 itself); Sorensen v. Shaklee Corp., 31 F.3d 638, 650 (8th Cir.1994) (affirming exclusion of expert witness opinions based upon animal mutagenicity data not germane to the claimed harm); Elkins v. Richardson-Merrell, Inc., 8 F.3d 1068, 1073 (6th Cir. 1993);Wade-Greaux v. Whitehall Labs., Inc., 874 F. Supp. 1441, 1482 (D.V.1. 1994), aff’d, 46 F.3d 1120 (3d Cir. 1994) (per curiam); Renaud v. Martin Marietta Corp., Inc., 972 F.2d 304, 307 (10th Cir.1992) (“The etiological evidence proffered by the plaintiff was not sufficiently reliable, being drawn from tests on non-human subjects without confirmatory epidemiological data.”) (“Dr. Jackson performed no calculations to determine whether the dose or route of administration of antidepressants to rats and monkeys in the papers that she cited in her report was equivalent to or substantially similar to human beings taking prescribed doses of Prozac.”); Bell v. Swift Adhesives, Inc., 804 F. Supp. 1577, 1579–81 (S.D. Ga. 1992) (excluding expert opinion of Dr. Janette Sherman, who opined that methylene chloride caused liver cancer, based largely upon on animal studies); Conde v. Velsicol Chem. Corp., 804 F. Supp. 972, 1025-26 (S.D. Ohio 1992) (noting that epidemiology is “the primary generally accepted methodology for demonstrating a causal relation between a chemical compound and a set of symptoms or a disease”), aff’d, 24 F.3d 809 (6th Cir. 1994); Turpin v. Merrell Dow Pharm., Inc., 959 F.2d 1349, 1360-61 (6th Cir. 1992) (“The analytical gap between the [animal study] evidence presented and the inferences to be drawn on the ultimate issue of human birth defects is too wide. Under such circumstances, a jury should not be asked to speculate on the issue of causation.”); Brock v. Merrell Dow Pharm., 874F.2d 307, 313 (5th Cir. 1989) (noting the “very limited usefulness of animal studies when confronted with questions of toxicity”); Richardson v. Richardson-Merrell, Inc., 857 F. 2d 823, 830 (D.C. Cir. 1988) (“Positive results from in vitro studies may provide a clue signaling the need for further research, but alone do not provide a satisfactory basis for opining about causation in the human context.”);  Lynch v. Merrell-Nat‘l Labs., 830 F.2d 1190, 1194 (1st Cir. 1987) (“Studies of this sort [animal studies], singly or in combination, do not have the capability of proving causation in human beings in the absence of any confirmatory epidemiological data.”). See also Merrell Dow Pharrns., Inc. v. Havner, 953 S.W.2d 706, 730 (Tex. 1997); DePyper v. Navarro, No. 83-303467-NM, 1995 WL 788828, at *34 (Mich. Cir. Ct. Nov. 27, 1995), aff’d, No. 191949, 1998 WL 1988927 (Mich. Ct. App. Nov. 6, 1998); Nelson v. American Sterilizer Co., 566 N.W.2d 671 (Mich. Ct. App. 1997)(high-dose animal studies not reliable). But see Ambrosini v. Labarraque,  101 F.3d 129, 137-140 (D.C. Cir.1996); Dyson v. Winfield, 113 F. Supp. 2d 44, 50-51 (D.D.C. 2000).

[21] Teratology Society Public Affairs Committee, “Position Paper Causation in Teratology-Related Litigation,” 73 Birth Defects Research (Part A) 421 (2005) [Teratology Position Paper]

[22] Id. at 423.

[23]  SeeImproper Reliance Upon Regulatory Risk Assessments in Civil Litigation” (Mar. 19, 2023) (collecting cases).

[24] Teratology Position Paper at 422-423.

[25] See, e.g., Gideon Koren, Anne Pastuszak & Shinya Ito, “Drugs in Pregnancy,” 338 New England J. Med. 1128, 1131 (1998); Louis Lasagna, “Predicting Human Drug Safety from Animal Studies: Current Issues,” 12 J. Toxicological Sci. 439, 442-43 (1987).

[26] Bruce N. Ames & Lois S. Gold, Too Many Rodent Carcinogens: Mitogenesis Increases Mutagenesis, 249 Science 970, 970 (1990) (noting that chronic irritation induced by many chemicals at high exposures is itself a cause of cancer in rodent models); Bruce N. Ames & Lois Swirsky Gold, “Environmental Pollution and Cancer: Some Misconceptions,” in Jay H. Lehr, ed., Rational Readings on Environmental Concerns 151, 153 (1992); Mary Eubanks, “The Danger of Extrapolation: Humans and Rodents Differ in Response to PCBs,” 112 Envt’l Health Persps. A113 (2004)

[27] Andrea Gawrylewski, “The Trouble with Animal Models: Why did human trials fail?” 21 The Scientist 44 (2007); Michael B. Bracken, “Why animal studies are often poor predictors of human reactions to exposure,” 101 J. Roy. Soc. Med. 120 (2008); Fiona Godlee, “How predictive and productive is animal research?” 3348 Brit. Med. J. g3719 (2014); John P. A. Ioannidis, “Extrapolating from Animals to Humans,” 4 Science Translational Med. 15 (2012); Pandora Pound & Michael Bracken, “Is animal research sufficiently evidence based to be a cornerstone of biomedical research?” 348 Brit. Med. J. g3387 (2014); Pandora Pound, Shah Ebrahim, Peter Sandercock, Michael B Bracken, and Ian Roberts, “Where is the evidence that animal research benefits humans?” 328 Brit. Med. J. 514 (2004) (writing on behalf of the Reviewing Animal Trials Systematically (RATS) Group).

[28] See Ray Greek, Niall Shanks, and Mark J. Rice, “The History and Implications of Testing Thalidomide on Animals,” 11 J. Philosophy, Sci. & Law 1, 19 (2011).

[29] Austin Bradford Hill, “Observation and Experiment,” 248 New Engl. J. Med. 995, 999 (1953).

Improper Reliance upon Regulatory Risk Assessments in Civil Litigation

March 19th, 2022

Risk assessments would seemingly be about assessing risks, but they are not. The Reference Manual on Scientific Evidence defines “risk” as “[a] probability that an event will occur (e.g., that an individual will become ill or die within a stated period of time or by a certain age).”[1] The risk in risk assessment, however, may be zero, or uncertain, or even a probability of benefit. Agencies that must assess risks and set “action levels,” or “permissible exposure limits,” or “acceptable intakes,” often work under great uncertainty, with inspired guesswork, using unproven assumptions.

The lawsuit industry has thus often embraced the false equivalence between agency pronouncements on harmful medicinal, environmental, or occupational exposures and civil litigation adjudication of tortious harms. In the United States, federal agencies such as the Occupational Safety and Health Administration (OSHA), or the Environmental Protection Agency (EPA), and their state analogues, regularly set exposure standards that could not and should not hold up in a common-law tort case. 

Remarkably, there are state and federal court judges who continue to misunderstand and misinterpret regulatory risk assessments, notwithstanding efforts to educate the judiciary. The second edition of the Reference Manual on Scientific Evidence contained a chapter by the late Professor Margaret Berger, who took pains to point out the difference between agency assessments and the adjudication of causal claims in court:

[p]roof of risk and proof of causation entail somewhat different questions because risk assessment frequently calls for a cost-benefit analysis. The agency assessing risk may decide to bar a substance or product if the potential benefits are outweighed by the possibility of risks that are largely unquantifiable because of presently unknown contingencies. Consequently, risk assessors may pay heed to any evidence that points to a need for caution, rather than assess the likelihood that a causal relationship in a specific case is more likely than not.[2]

In March 2003, Professor Berger organized a symposium,[3] the first Science for Judges program (and the last), where the toxicologist Dr. David L. Eaton presented on the differences in the use of toxicology in regulatory pronouncements as opposed to causal assessments in civil actions. As Dr. Eaton noted:

“regulatory levels are of substantial value to public health agencies charged with ensuring the protection of the public health, but are of limited value in judging whether a particular exposure was a substantial contributing factor to a particular individual’s disease or illness.”[4]

The United States Environmental Protection Agency (EPA) acknowledges that estimating “risk” from low level exposures based upon laboratory animal data is fraught because of inter-specie differences in longevity, body habitus and size, genetics, metabolism, excretion patterns, genetic homogeneity of laboratory animals, dosing levels and regimens. The EPA’s assumptions in conducting and promulgating regulatory risk assessments are intended to predict the upper bound of theoretical risk, while fully acknowledging that there may be no actual risk in humans:

“It should be emphasized that the linearized multistage [risk assessment] procedure leads to a plausible upper limit to the risk that is consistent with some proposed mechanisms of carcinogenesis. Such an estimate, however, does not necessarily give a realistic prediction of the risk. The true value of the risk is unknown, and may be as low as zero.”[5]

The approach of the U.S. Food and Drug Administration (FDA) with respect to mutagenic impurities in medications provides an illustrative example of how theoretical and hypothetical risk assessment can be.[6] The FDA’s risk assessment approach is set out in a “Guidance” document, which like all such FDA guidances, describes itself as containing non-binding recommendations, which do not preempt alternative approaches.[7] The agency’s goal is devise a control strategy for any mutagenic impurity to keep it at or below an “acceptable cancer risk level,” even if the risk or the risk level is completely hypothetical.

The FDA guidance advances the concept of a “Threshold of Toxicological Concern (TTC),” to set an “acceptable intake,” for chemical impurities that pose negligible risks of toxicity or carcinogenicity.[8] The agency describes its risk assessment methodology as “very conservative,” given the frequently unproven assumptions made to reach a quantification of an “acceptable intake”:

“The methods upon which the TTC is based are generally considered to be very conservative since they involve a simple linear extrapolation from the dose giving a 50% tumor incidence (TD50) to a 1 in 10-6 incidence, using TD50 data for the most sensitive species and most sensitive site of tumor induction. For application of a TTC in the assessment of acceptable limits of mutagenic impurities in drug substances and drug products, a value of 1.5 micrograms (µg)/day corresponding to a theoretical 10-5 excess lifetime risk of cancer can be justified.”

For more potent mutagenic carcinogens, such as aflatoxin-like-, N-nitroso-, and alkyl-azoxy compounds, the acceptable intake or permissible daily exposure (PDE) is set lower, based upon available animal toxicologic data.

The important divide between regulatory practice and the litigation of causal claims in civil actions arises from the theoretical nature of the risk assessment enterprise. The FDA acknowledges, for instance, that the acceptable intake is set to mark “a small theoretical increase in risk,” and a “highly hypothetical concept that should not be regarded as a realistic indication of the actual risk,” and thus not an actual risk.[9] The corresponding hypothetical or theoretical risk to the acceptable intake level is clearly small when compared with the human’s lifetime probability of developing cancer (which the FDA states is greater than 1/3, but probably now approaches 40%).

Although the TTC concept allows a calculation of an estimated “safe exposure,” the FDA points out that:

“exceeding the TTC is not necessarily associated with an increased cancer risk given the conservative assumptions employed in the derivation of the TTC value. The most likely increase in cancer incidence is actually much less than 1 in 100,000. *** Based on all the above considerations, any exposure to an impurity that is later identified as a mutagen is not necessarily associated with an increased cancer risk for patients already exposed to the impurity. A risk assessment would determine whether any further actions would be taken.”

In other words the FDA’s risk assessment exists to guide agency action, not to determine a person’s risk or medical status.[10]

As small and theoretical as the risks are, they are frequently based upon demonstrably incorrect assumptions, such as:

  1. humans are as sensitive as the most sensitive species;
  2. all organs are as sensitive as the most sensitive organ of the most sensitive species;
  3. the dose-response in the most sensitive species is a simple linear relationship;
  4. the linear relationship runs from zero exposure and zero risk to the exposure that yields the so-called TD50, the exposure that yields tumors in 50% of the experimental animal model;
  5. the TD-50 is calculated based upon the point estimate in the animal model study, regardless of any confidence interval around the point estimate;
  6. the inclusion, in many instances, of non-malignant tumors as part of the assessment of the TD50 exposure;
  7. there is some increased risk for any exposure, no matter how small; that is, there is no threshold below which there is no increased risk; and
  8. the medication with the mutagenic impurity was used daily for 70 years, by a person who weights 50 kg.

Although the FDA acknowledges that there may be some instances in which a “less than lifetime level” (LTL) may be appropriate, it places the burden on manufacturers to show the appropriateness of higher LTLs. The FDA’s M7 Guidance observes that

“[s]tandard risk assessments of known carcinogens assume that cancer risk increases as a function of cumulative dose. Thus, cancer risk of a continuous low dose over a lifetime would be equivalent to the cancer risk associated with an identical cumulative exposure averaged over a shorter duration.”[11]

Similarly, the agency acknowledges that there may be a “practical threshold,” as result of bodily defense mechanisms, such as DNA repair, which counter any ill effects from lower level exposures.[12]

“The existence of mechanisms leading to a dose response that is non-linear or has a practical threshold is increasingly recognized, not only for compounds that interact with non-DNA targets but also for DNA-reactive compounds, whose effects may be modulated by, for example, rapid detoxification before coming into contact with DNA, or by effective repair of induced damage. The regulatory approach to such compounds can be based on the identification of a No-Observed Effect Level (NOEL) and use of uncertainty factors (see ICH Q3C(R5), Ref. 7) to calculate a permissible daily exposure (PDE) when data are available.”

Expert witnesses often attempt to bootstrap their causation opinions by reference to determinations of regulatory agencies that are couched in similar language, but which use different quality and quantity of evidence than is required in the scientific community or in civil courts.

Supreme Court

Industrial Union Dep’t v. American Petroleum Inst., 448 U.S. 607, 656 (1980) (“OSHA is not required to support its finding that a significant risk exists with anything approaching scientific certainty” and “is free to use conservative assumptions in interpreting the data with respect to carcinogens, risking error on the side of overprotection, rather than underprotection.”).

Matrixx Initiatives, Inc. v. Siracusano, 563 U.S. 27, 131 S.Ct. 1309, 1320 (2011) (regulatory agency often makes regulatory decisions based upon evidence that gives rise only to a suspicion of causation) 

First Circuit

Sutera v. Perrier Group of America, Inc., 986 F. Supp. 655, 664-65, 667 (D. Mass. 1997) (a regulatory agency’s “threshold of proof is reasonably lower than that in tort law”; “substances are regulated because of what they might do at given levels, not because of what they will do. . . . The fact of regulation does not imply scientific certainty. It may suggest a decision to err on the side of safety as a matter of regulatory policy rather than the existence of scientific fact or knowledge. . . . The mere fact that substances to which [plaintiff] was exposed may be listed as carcinogenic does not provide reliable evidence that they are capable of causing brain cancer, generally or specifically, in [plaintiff’s] case.”); id. at 660 (warning against the danger that a jury will “blindly accept an expert’s opinion that conforms with their underlying fears of toxic substances without carefully understanding or examining the basis for that opinion.”). Sutera is an important precedent, which involved a claim that exposure to an IARC category I carcinogen, benzene, caused plaintiffs’ leukemia. The plaintiff’s expert witness, Robert Jacobson, espousing a “linear, no threshold” theory, and relying upon an EPA regulation, which he claimed supported his opinion that even trace amounts of benzene can cause leukemia.

In re Neurontin Mktg., Sales Practices, and Prod. Liab. Litig., 612 F. Supp. 2d 116, 136 (D. Mass. 2009) (‘‘It is widely recognized that, when evaluating pharmaceutical drugs, the FDA often uses a different standard than a court does to evaluate evidence of causation in a products liability action. Entrusted with the responsibility of protecting the public from dangerous drugs, the FDA regularly relies on a risk-utility analysis, balancing the possible harm against the beneficial uses of a drug. Understandably, the agency may choose to ‘err on the side of caution,’ … and take regulatory action such as revising a product label or removing a drug from the marketplace ‘upon a lesser showing of harm to the public than the preponderance-of-the-evidence or more-like-than-not standard used to assess tort liability’.’’) (internal citations omitted) 

Whiting v. Boston Edison Co., 891 F. Supp. 12, 23-24 (D. Mass. 1995) (criticizing the linear no-threshold hypothesis, common to regulatory risk assessments, because it lacks any known or potential error rate, and it cannot be falsified as would any scientific theory)

Second Circuit

Wills v. Amerada Hess Corp., No. 98 CIV. 7126(RPP), 2002 WL 140542 (S.D.N.Y. Jan. 31, 2002), aff’d, 379 F.3d 32 (2d Cir. 2004) (Sotomayor, J.). In this Jones Act case, the plaintiff claimed that her husband’s exposure to benzene and polycyclic aromatic hydrocarbons on board ship caused his squamous cell lung cancer. Plaintiff’s expert witness relied heavily upon the IARC categorization of benzene as a “known” carcinogen, and an “oncogene” theory of causation that claimed there was no safe level of exposure because a single molecule could induce cancer. According to the plaintiff’s expert witness, the oncogene theory dispensed with the need to quantify exposure. Then Judge Sotomayor, citing Sutera, rejected plaintiff’s no-threshold theory, and the argument that exposure that exceeded OHSA permissible exposure level supported the causal claim.

Mancuso v. Consolidated Edison Co., 967 F. Supp. 1437, 1448 (S.D.N.Y. 1997) (“recommended or prescribed precautionary standards cannot provide legal causation”; “[f]ailure to meet regulatory standards is simply not sufficient” to establish liability)

In re Agent Orange Product Liab. Litig., 597 F. Supp. 740, 781 (E.D.N.Y. 1984) (Weinstein, J.) (“The distinction between avoidance of risk through regulation and compensation for injuries after the fact is a fundamental one.”), aff’d in relevant part, 818 F.2d 145 (2d Cir.1987), cert. denied sub nom. Pinkney v. Dow Chemical Co., 484 U.S. 1004 (1988). Judge Weinstein explained that regulatory action would not by itself support imposing liability for an individual plaintiff.  Id. at 782. “A government administrative agency may regulate or prohibit the use of toxic substances through rulemaking, despite a very low probability of any causal relationship.  A court, in contrast, must observe the tort law requirement that a plaintiff establish a probability of more than 50% that the defendant’s action injured him.” Id. at 785.

In re Ephedra Prods. Liab. Litig., 393 F. Supp. 2d 181, 189 (S.D.N.Y. 2005) (improvidently relying in part upon FDA ban despite “the absence of definitive scientific studies establishing causation”)

Third Circuit

Gates v. Rohm & Haas Co., 655 F.3d 255, 268 (3d Cir. 2011) (affirming the denial of class certification for medical monitoring) (‘‘plaintiffs could not carry their burden of proof for a class of specific persons simply by citing regulatory standards for the population as a whole’’).

In re Schering-Plough Corp. Intron/Temodar Consumer Class Action, 2009 WL 2043604, at *13 (D.N.J. July 10, 2009)(“[T]here is a clear and decisive difference between allegations that actually contest the safety or effectiveness of the Subject Drugs and claims that merely recite violations of the FDCA, for which there is no private right of action.”)

Rowe v. E.I. DuPont de Nemours & Co., Civ. No. 06-1810 (RMB), 2008 U.S. Dist. LEXIS 103528, *46-47 (D.N.J. Dec. 23, 2008) (rejecting reliance upon regulatory findings and risk assessments in which “the basic goal underlying risk assessments . . . is to determine a level that will protect the most sensitive members of the population.”)  (quoting David E. Eaton, “Scientific Judgment and Toxic Torts – A Primer in Toxicology for Judges and Lawyers,” 12 J.L. & Pol’y 5, 34 (2003) (“a number of protective, often ‘worst case’ assumptions . . . the resulting regulatory levels . . . generally overestimate potential toxicity levels for nearly all individuals.”)

Soldo v. Sandoz Pharms. Corp., 244 F. Supp. 2d 434, 543 (W.D. Pa. 2003) (finding FDA regulatory proceedings and adverse event reports not adequate or helpful in determining causation; the FDA “ordinarily does not attempt to prove that the drug in fact causes a particular adverse effect.”)Wade-Greaux v. Whitehall Laboratories, Inc., 874 F. Supp. 1441, 1464 (D.V.I.) (“assumption[s that] may be useful in a regulatory risk-benefit context … ha[ve] no applicability to issues of causation-in-fact”), aff’d, 46 F.3d 1120 (3d  Cir. 1994)

O’Neal v. Dep’t of the Army, 852 F. Supp. 327, 333 (M.D. Pa. 1994) (administrative risk figures are “appropriate for regulatory purposes in which the goal is to be particularly cautious [but] overstate the actual risk and, so, are inappropriate for use in determining” civil liability)

Fourth Circuit

Dunn v. Sandoz Pharmaceuticals Corp., 275 F. Supp. 2d 672, 684 (M.D.N.C. 2003) (FDA “risk benefit analysis” “does not demonstrate” causation in any particular plaintiff)

Yates v. Ford Motor Co., 113 F. Supp. 3d 841, 857 (E.D.N.C. 2015) (“statements from regulatory and official agencies … are not bound by standards for causation found in toxic tort law”)

Meade v. Parsley, No. 2:09-cv-00388, 2010 U.S. Dist. LEXIS 125217, * 25 (S.D.W. Va. Nov. 24, 2010) (‘‘Inasmuch as the cost-benefit balancing employed by the FDA differs from the threshold standard for establishing causation in tort actions, this court likewise concludes that the FDA-mandated [black box] warnings cannot establish general causation in this case.’’)

Rhodes v. E.I. du Pont de Nemours & Co., 253 F.R.D. 365, 377 (S.D. W.Va. 2008) (rejecting the relevance of regulatory assessments, which are precautionary and provide no information about actual risk).

Fifth Circuit

Moore v. Ashland Chemical Co., 126 F.3d 679, 708 (5th Cir. 1997) (holding that expert witness could rely upon a material safety data sheet (MSDS) because mandated by the Hazard Communication Act, 29 C.F.R. § 1910.1200), vacated 151 F.3d 269 (5th Cir. 1998) (affirming trial court’s exclusion of expert witness who had relied upon MSDS).

Johnson v. Arkema Inc., 685 F.3d 452, 464 (5th Cir. 2012) (per curiam) (affirming exclusion of expert witness who upon regulatory pronouncements; noting the precautionary nature of such statements, and the absence of specificity for the result claimed at the exposures experienced by plaintiff)

Allen v. Pennsylvania Eng’g Corp., 102 F.3d 194, 198-99 (5th Cir. 1996) (“Scientific knowledge of the harmful level of exposure to a chemical, plus knowledge that the plaintiff was exposed to such quantities, are minimal facts necessary to sustain the plaintiffs’ burden in a toxic tort case”; regulatory agencies, charged with protecting public health, employ a lower standard of proof in promulgating regulations than that used in tort cases). The Allen court explained that it was “also unpersuaded that the “weight of the evidence” methodology these experts use is scientifically acceptable for demonstrating a medical link. . . .  Regulatory and advisory bodies. . .utilize a “weight of the evidence” method to assess the carcinogenicity of various substances in human beings and suggest or make prophylactic rules governing human exposure.  This methodology results from the preventive perspective that the agencies adopt in order to reduce public exposure to harmful substances.  The agencies’ threshold of proof is reasonably lower than that appropriate in tort law, which traditionally makes more particularized inquiries into cause and effect and requires a plaintiff to prove that it is more likely than not that another individual has caused him or her harm.” Id.

Burst v. Shell Oil Co., C. A. No. 14–109, 2015 WL 3755953, *8 (E.D. La. June 16, 2015) (explaining Fifth Circuit’s rejection of regulatory “weight of the evidence” approaches to evaluating causation)

Sprankle v. Bower Ammonia & Chem. Co., 824 F.2d 409, 416 (5th Cir. 1987) (affirmed Rule 403 exclusion evidence of OSHA violations in claim of respiratory impairment in a non-employee who experienced respiratory impairment after exposure to anhydrous ammonia; court found that the jury likely be confused by regulatory pronouncements)

Cano v. Everest Minerals Corp., 362 F. Supp. 2d 814, 825 (W.D. Tex. 2005) (noting that a product that “has been classified as a carcinogen by agencies responsible for public health regulations is not probative of” common-law specific causation) (finding that the linear no-threshold opinion of the plaintiffs’ expert witness, Malin Dollinger, lacked a satisfactory scientific basis)

Burleson v. Glass, 268 F. Supp. 2d 699, 717 (W.D. Tex. 2003) (“the mere fact that [the product] has been classified by certain regulatory organizations as a carcinogen is not probative on the issue of whether [plaintiff’s] exposure. . .caused his. . .cancers”), aff’d, 393 F.3d 577 (5th Cir. 2004)

Newton v. Roche Labs., Inc., 243 F. Supp. 2d 672, 677, 683 (W.D. Tex. 2002) (FDA’s precautionary decisions on labeling are not a determination of causation of specified adverse events) (“Although evidence of an association may … be important in the scientific and regulatory contexts…, tort law requires a higher standard of causation.”)

Molden v. Georgia Gulf Corp., 465 F. Supp. 2d 606, 611 (M.D. La. 2006) (“regulatory and advisory bodies make prophylactic rules governing human exposure based on proof that is reasonably lower than that appropriate in tort law”)

Sixth Circuit

Nelson v. Tennessee Gas Pipeline Co., 243 F.3d 244, 252-53 (6th Cir. 2001) (exposure above regulatory levels is insufficient to establish causation)

Stites v Sundstrand Heat Transfer, Inc., 660 F. Supp. 1516, 1525 (W.D. Mich. 1987) (rejecting use of regulatory standards to support claim of increased risk, noting the differences in goals and policies between regulation and litigation)

Mann v. CSX Transportation, Inc., case no. 1:07-Cv-3512, 2009 U.S. Dist. Lexis 106433 (N.D. Ohio Nov. 10, 2009) (rejecting expert testimony that relied upon EPA action levels, and V.A. compensation for dioxin exposure, as basis for medical monitoring opinions)

Baker v. Chevron USA, Inc., 680 F. Supp. 2d 865, 880 (S.D. Ohio 2010) (“[R]egulatory agencies are charged with protecting public health and thus reasonably employ a lower threshold of proof in promulgating their regulations than is used in tort cases.”) (“[t]he mere fact that Plaintiffs were exposed to [the product] in excess of mandated limits is insufficient to establish causation”; rejecting Dr. Dahlgren’s opinion and its reliance upon a “one-hit” or “no threshold” theory of causation in which exposure to one molecule of a cancer-causing agent has some finite possibility of causing a genetic mutation leading to cancer, a theory that may be accepted for purposes of setting regulatory standards, but not as reliable scientific knowledge)

Adams v. Cooper Indus., 2007 WL 2219212 at *7 (E.D. KY 2007).

Seventh Circuit

Wood v. Textron, Inc., No. 3:10 CV 87, 2014 U.S. Dist. LEXIS 34938 (N.D. Ind. Mar. 17, 2014); 2014 U.S. Dist. LEXIS 141593, at *11 (N.D. Ind. Oct. 3, 2014), aff’d, 807 F.3d 827 (7th Cir. 2015). Dahlgren based his opinions upon the children’s water supply containing vinyl chloride in excess of regulatory levels set by state and federal agencies, including the EPA. Similarly, Ryer-Powder relied upon exposure levels’ exceeding regulatory permissible limits for her causation opinions. The district court, with the approval now of the Seventh Circuit would have none of this nonsense. Exceeding governmental regulatory exposure limits does not prove causation. The con-compliance does not help the fact finder without knowing “the specific dangers” that led the agency to set the permissible level, and thus the regulations are not relevant at all without this information. Even with respect to specific causation, the regulatory infraction may be weak or null evidence for causation. (citing Cunningham v. Masterwear Corp., 569 F.3d 673, 674–75 (7th Cir. 2009)

Eighth Circuit

Glastetter v. Novartis Pharms. Corp., 107 F. Supp. 2d 1015, 1036 (E.D. Mo. 2000) (“[T]he [FDA’s] statement fails to affirmatively state that a connection exists between [the drug] and the type of injury in this case.  Instead, it states that the evidence received by the FDA calls into question [drug’s] safety, that [the drug] may be an additional risk factor. . .and that the FDA had new evidence suggesting that therapeutic use of [the drug] may lead to serious adverse experiences.  Such language does not establish that the FDA had concluded that [the drug] can cause [the injury]; instead, it indicates that in light of the limited social utility of [the drug for the use at issue] and the reports of possible adverse effects, the drug should no longer be used for that purpose.”) (emphasis in original), aff’d, 252 F.3d 986, 991 (8th Cir. 2001) (FDA’s precautionary decisions on labeling are not a determination of causation of specified adverse events; “methodology employed by a government agency results from the preventive perspective that the agencies adopt”)( “The FDA will remove drugs from the marketplace upon a lesser showing of harm to the public than the preponderance-of-the-evidence or the more-like-than-not standard used to assess tort liability . . . . [Its] decision that [the drug] can cause [the injury] is unreliable proof of medical causation.”), aff’d, 252 F.3d 986 (8th Cir. 2001)

Wright v. Willamette Indus., Inc., 91 F.3d 1105, 1107 (8th Cir. 1996) (rejecting claim that plaintiffs were not required to show individual exposure levels to formaldehyde from wood particles). The Wright court elaborated upon the difference between adjudication and regulation of harm:

“Whatever may be the considerations that ought to guide a legislature in its determination of what the general good requires, courts and juries, in deciding cases, traditionally make more particularized inquiries into matters of cause and effect.  Actions in tort for damages focus on the question of whether to transfer money from one individual to another, and under common-law principles (like the ones that Arkansas law recognizes) that transfer can take place only if one individual proves, among other things, that it is more likely than not that another individual has caused him or her harm.  It is therefore not enough for a plaintiff to show that a certain chemical agent sometimes causes the kind of harm that he or she is complaining of.  At a minimum, we think that there must be evidence from which the factfinder can conclude that the plaintiff was exposed to levels of that agent that are known to cause the kind of harm that the plaintiff claims to have suffered. See Abuan v. General Elec. Co., 3 F.3d at 333.  We do not require a mathematically precise table equating levels of exposure with levels of harm, but there must be evidence from which a reasonable person could conclude that a defendant’s emission has probablycaused a particular plaintiff the kind of harm of which he or she complains before there can be a recovery.”

Gehl v. Soo Line RR, 967 F.2d 1204, 1208 (8th Cir. 1992).

Nelson v. Am. Home Prods. Corp., 92 F. Supp. 2d 954, 958 (W.D. Mo. 2000) (FDA’s precautionary decisions on labeling are not a determination of causation of specified adverse events)

National Bank of Commerce v. Associated Milk Producers, Inc., 22 F. Supp. 2d 942, 961 (E.D.Ark. 1998), aff’d, 191 F.3d 858 (8th Cir. 1999) 

Junk v. Terminix Internat’l Co., 594 F. Supp. 2d 1062, 1071 (S.D. Iowa 2008) (“government agency regulatory standards are irrelevant to [plaintiff’s] burden of proof in a toxic tort cause of action because of the agency’s preventative perspective”)

Ninth Circuit

Henrickson v. ConocoPhillips Co., 605 F. Supp. 2d 1142, 1156 (E.D. Wash. 2009) (excluding expert witness causation opinions in case involving claims that benzene exposure caused leukemia) 

Lopez v. Wyeth-Ayerst Labs., Inc., 1998 WL 81296, at *2 (9th Cir. Feb. 25, 1998) (FDA’s precautionary decisions on labeling are not a determination of causation of specified adverse events)

In re Epogen & Aranesp Off-Label Marketing & Sales Practices Litig., 2009 WL 1703285, at *5 (C.D. Cal. June 17, 2009) (“have not been proven” allegations are an improper “FDA approval” standard; the FDA’s determination to require warning changes without establishing causation is established does not permit a court or jury, bound by common-law standards, to impose such a duty to warn when common-law causation requirements are not met).

In re Hanford Nuclear Reservation Litig., 1998 U.S. Dist. Lexis 15028 (E.D. Wash. 1998) (radiation and chromium VI), rev’d on other grounds, 292 F.3d 1124 (9th Cir. 2002).

Tenth Circuit

Hollander v. Shandoz Pharm. Corp., 95 F. Supp. 2d 1230, 1239 (W.D. Okla. 2000) (distinguishing FDA’s threshold of proof as lower than appropriate in tort law), aff’d in relevant part, 289 F.3d 1193, 1215 (10th Cir. 2002)

Mitchell v. Gencorp Inc., 165 F.3d 778, 783 n.3 (10th Cir. 1999) (benzene and CML) (quoting Allen, 102 F.3d at 198) (state administrative finding that product was a carcinogen was based upon lower administrative standard than tort standard) (“The methodology employed by a government agency “results from the preventive perspective that the agencies adopt in order to reduce public exposure to harmful substances.  The agencies’ threshold of proof is reasonably lower than that appropriate in tort law, which traditionally makes more particularized inquiries into cause and effect and requires a plaintiff to prove it is more likely than not that another individual has caused him or her harm.”)

In re Breast Implant Litig., 11 F. Supp. 2d 1217, 1229 (D.Colo. 1998)

Johnston v. United States, 597 F. Supp. 374, 393-394 (D. Kan.1984) (noting that the linear no-threshold hypothesis is based upon a prudent assumption designed to overestimate risk; speculative hypotheses are not appropriate in determining whether one person has harmed another)

Eleventh Circuit

Rider v. Sandoz Pharmaceuticals Corp., 295 F.3d 1194, 1201 (11th Cir. 2002) (FDA may take regulatory action, such as revising warning labels or withdrawing drug from the market ‘‘upon a lesser showing of harm to the public than the preponderance-of-the-evidence or more-likely-than-not standard used to assess tort liability’’) (“A regulatory agency such as the FDA may choose to err on the side of caution. Courts, however, are required by the Daubert trilogy to engage in objective review of the evidence to determine whether it has sufficient scientific basis to be considered reliable.”)

McClain v. Metabolife Internat’l, Inc., 401 F.3d 1233, 1248-1250 (11th Cir. 2005) (ephedra) (allowing that regulators “may pay heed to any evidence that points to a need for caution,” and apply “a much lower standard than that which is demanded by a court of law”) (“[U]se of FDA data and recommendations raises a more subtle methodological issue in a toxic tort case. The issue involves identifying and contrasting the type of risk assessment that a government agency follows for establishing public health guidelines versus an expert analysis of toxicity and causation in a toxic tort case.”)

In re Seroquel Products Liab. Litig., 601 F. Supp. 2d 1313, 1315 (M.D. Fla. 2009) (noting that administrative agencies “impose[] different requirements and employ[] different labeling and evidentiary standards” because a “regulatory system reflects a more prophylactic approach” than the common law)

Siharath v. Sandoz Pharmaceuticals Corp., 131 F. Supp. 2d 1347, 1370 (N.D. Ga. 2001) (“The standard by which the FDA deems a drug harmful is much lower than is required in a court of law.  The FDA’s lesser standard is necessitated by its prophylactic role in reducing the public’s exposure to potentially harmful substances.”), aff’d, 295 F.3d 1194 330 (11th Cir. 2002)

In re Accutane Products Liability, 511 F.Supp.2d 1288, 1291-92 (M.D. Fla. 2007)(acknowledging that regulatory risk assessments are not necessarily realistic in human populations because they are often based upon animal studies, and that the important differences between experimental animals and humans are substantial in various health outcomes).

Kilpatrick v. Breg, Inc., 2009 WL 2058384 at * 6-7 (S.D. Fla. 2009) (excluding plaintiff’s expert witness), aff’d, 613 F.3d 1329 (11th Cir. 2010)

District of Columbia Circuit

Ethyl Corp. v. E.P.A., 541 F.2d 1, 28 & n. 58 (D.C. Cir. 1976) (detailing the precautionary nature of agency regulations that may be based upon suspicions)

STATE COURTS

Arizona

Lofgren v. Motorola, 1998 WL 299925 (Ariz. Super. Ct. 1998) (finding plaintiffs’ expert witnesses’ testimony that TCE caused cancer to be not generally accepted; “it is appropriate public policy for health organizations such as IARC and the EPA to make judgments concerning the health and safety of the population based on evidence which would be less than satisfactory to support a specific plaintiff’s tort claim for damages in a court of law”)

Colorado

Salazar v. American Sterilizer Co., 5 P.3d 357 (Colo. Ct. App. 2000) (allowing testimony about harmful ethylene oxide exposure based upon OSHA regulations)

Georgia

Butler v. Union Carbide Corp., 712 S.E.2d 537, 552 & n.37 (Ga. App. 2011) (distinguishing risk assessment from causation assessment; citing the New York Court of Appeals decision in Parker for correctly rejecting reliance on regulatory pronouncements for causation determinations)

Illinois

La Salle Nat’l Bank v. Malik, 705 N.E.2d 938 (Ill. App. 3d) (reversing trial court’s exclusion of OSHA PEL for ethylene oxide), writ pet’n den’d, 714 N.E.2d 527 (Ill. 2d 1999)

New York

Parker v. Mobil Oil Corp., 7 N.Y.3d 434, 450, 857 N.E.2d 1114, 1122, 824 N.Y.S.2d 584 (N.Y. 2006) (noting that regulatory agency standards usually represent precautionary principle efforts deliberately to err on side of prevention; “standards promulgated by regulatory agencies as protective measures are inadequate to demonstrate legal causation.” 

In re Bextra & Celebrex, 2008 N.Y. Misc. LEXIS 720, *20, 239 N.Y.L.J. 27 (2008) (characterizing FDA Advisory Panel recommendations as regulatory standard and protective measure).

Juni v. A.O. Smith Water Products Co., 48 Misc. 3d 460, 11 N.Y.S.3d 416, 432, 433 (N.Y. Cty. 2015) (“the reports and findings of governmental agencies [declaring there to be no safe dose of asbestos] are irrelevant as they constitute insufficient proof of causation”), aff’d, 32 N.Y.3d 1116, 116 N.E.3d 75, 91 N.Y.S.3d 784 (2018)

Ohio

Valentine v. PPG Industries, Inc., 821 N.E.2d 580, 597-98 (Ohio App. 2004), aff’d, 850 N.E.2d 683 (Ohio 2006). 

Pennsylvania

Betz v. Pneumo Abex LLC, 44 A. 3d 27 (Pa. 2012).

Texas

Borg-Warner Corp., 232 S.W.3d 765, 770 (Tex. 2007)

Exxon Corp. v. Makofski, 116 S.W.3d 176, 187-88 (Tex. App. 2003) (describing “standards used by OSHA [and] the EPA” as inadequate for causal determinations)


[1] Michael D. Green, D. Michal Freedman, and Leon Gordis, “Reference Guide on Epidemiology,” in Reference Manual on Scientific Evidence 549, 627 (3d ed. 2011).

[2] Margaret A. Berger, “The Supreme Court’s Trilogy on the Admissibility of Expert Testimony,” in Reference Manual On Scientific Evidence at 33 (Fed. Jud. Center 2d. ed. 2000).

[3] Margaret A. Berger, “Introduction to the Symposium,” 12 J. L. & Pol’y 1 (2003). Professor Berger described the symposium as a “felicitous outgrowth of a grant from the Common Benefit Trust established in the Silicone Breast Implant Products Liability Litigation to hold a series of conferences at Brooklyn Law School.” Id. at 1. Ironically, that “Trust” was nothing more than the walking-around money of plaintiffs’ lawyers from the Silicone-Gel Breast Implant MDL 926. Although Professor Berger was often hostile the causation requirement in tort law, her symposium included some well-qualified scientists who amplified her point from the Reference Manual about the divide between regulatory risk assessment and scientific causal assessments.

[4] David L. Eaton, Scientific Judgment and Toxic Torts- A Primer in Toxicology for Judges and Lawyers, 12 J.L. & Pol’y 5, 36 (2003). See also Joseph V. Rodricks and Susan H. Rieth, “Toxicological risk assessment in the courtroom: are available methodologies suitable for evaluating toxic tort and product liability claims?” 27 Regul. Toxicol. & Pharmacol. 21, 27 (1998) (“The public health-oriented resolution of scientific uncertainty [used by regulators] is not especially helpful to the problem faced by a court.”)

[5] EPA “Guidelines for Carcinogen Risk Assessment” at 13 (1986).

[6] The approach is set out in FDA, M7 (R1) Assessment and Control of DNA Reactive (Mutagenic) Impurities in Pharmaceuticals to Limit Potential Carcinogenic Risk: Guidance for Industry (2018) [FDA M7]. This FDA guidance is essentially an adoption of the M7 document of the Expert Working Group (Multidisciplinary) of the International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use (ICH).

[7] FDA M7 at 3.

[8] FDA M7 at 5.

[9] FDA M7 at 5 (emphasis added).

[10] See Labeling of Diphenhydramine Containing Drug Products for Over-the-Counter Human Use, 67 Fed. Reg. 72,555, at 72,556 (Dec. 6, 2002) (“FDA’s decision to act in an instance such as this one need not meet the standard of proof required to prevail in a private tort action. . .. To mandate a warning or take similar regulatory action, FDA need not show, nor do we allege, actual causation.”) (citing Glastetter).

[11] FDA M7 at “Acceptable Intakes in Relation to Less-Than-Lifetime (LTL) Exposure (7.3).”

[12] FDA M7 at 12 (“Mutagenic Impurities With Evidence for a Practical Threshold (7.2.2)”).

California Roasts Fear-Mongering Industry

June 16th, 2019

A year ago, California set out to create an exemption for coffee from its Proposition 65 regulations. The lawsuit industry, represented by the Council for Education and Research on Toxics (CERT) had been successfully deploying Prop 65’s private right of action provisions to pick the pockets of coffee vendors. Something had to give.

In 2010, Mr. Metzger, on behalf of CERT, sued Starbucks and 90 other coffee manufacturers and distributors, claiming they had failed to warn consumers about the cancer risks of acrylamide. CERT’s mission was to shake down the roasters and the vendors because coffee has minor amounts of acrylamide in it. Acrylamide in very high doses causes tumors in rats[1]; coffee consumption by humans is generally regarded as beneficial.

Earlier last year a Los Angeles Superior Court ordered the coffee companies to put cancer warnings on their beverages. In the upcoming damages phase of the case, Metzger sought as much as $2,500 in civil penalties for each cup of coffee the defendants sold over at least a decade. Suing companies for violating California’s Proposition 65 is like shooting fish in a barrel, but the State’s regulatory initiative to save California from the embarrassment of branding coffee a carcinogen was a major setback for CERT.

And so the Office of Environmental Health Hazard Assessment (OEHHA) began a rulemaking largely designed to protect the agency from the public relations nightmare created by the application of the governing statute and regulations to squeeze the coffee roasters and makers.[2] The California’s agency’s proposed regulation on acrylamide in coffee resulted in a stay of CERT’s enforcement action against Starbucks.[3] CERT’s lawyers were not pleased; they had already won a trial court’s judgment that they were owed damages, and only the amount needed to be set. In September 2018, CERT filed a lawsuit in Los Angeles Superior Court against the state of California challenging OEHHA’s proposed rule, saying it was being rammed through the agency on the order of the Office of the Governor in an effort to kill CERT’s suit against the coffee companies. Or maybe it was simply designed to allow people to drink their coffee without the Big Prop 65 warning.

Earlier this month, after reviewing voluminous submissions and holding a hearing, the OEHHA announced its ruling that Californians do not need to be warned that coffee causes cancer. Epistemically, coffee is not known to the State of California to be hazardous to human health.[4] According to Sam Delson, a spokesperson for the OEHHA, “Coffee is a complex mixture of hundreds of chemicals that includes both carcinogens and anti-carcinogens. … The overall effect of coffee consumption is not associated with any significant cancer risk.” The regulation saving coffee goes into effect in October 2019. CERT, no doubt, will press on in its litigation campaign against the State.

CERT is the ethically dodgy organization founded by C. Sterling Wolfe, a former environmental lawyer; Brad Lunn; Carl Cranor, a philosophy professor at University of California Riverside; and Martyn T. Smith, a toxicology professor at University of California Berkeley.[5] Metzger has been its lawyer for many years; indeed, Metzger and CERT share the same office. Smith has been the recipient of CERT’s largesse in funding toxicologic studies. Cranor and Smith have both testified for the lawsuit industry.

In the well-known Milward case,[6] both Cranor and Smith served as paid expert witnesses for plaintiff. When the trial court excluded their proffered testimonies as unhelpful and unreliable, their own organization, CERT, came to the rescue by filing an amicus brief in the First Circuit. Supporting by a large cast of fellow travelers, CERT perverted the course of justice by failing to disclose the intimate relationship between the “amicus” CERT and the expert witnesses Cranor and Smith, whose opinions had been successfully challenged.[7]

The OEHHA coffee regulation shows that not all regulation is bad.


[1]  National Cancer Institute, “Acrylamide and Cancer Risk.”

[2]  See Sam Delson, “Press Release: Proposed OEHHA regulation clarifies that cancer warnings are not required for coffee under Proposition 65” (June 15, 2018).

[3]  Council for Education and Research on Toxics v. Starbucks Corp., case no. B292762, Court of Appeal of the State of California, Second Appellate District.

[4]  Associated Press, “Perk Up: California Says Coffee Cancer Risk Insignificant,” N.Y. Times (June 3, 2019); Sara Randazzo, “Coffee Doesn’t Warrant a Cancer Warning in California, Agency Says; Industry scores win following finding on chemical found in beverage,” W.S.J. (June 3, 2019); Editorial Board, “Coffee Doesn’t Kill After All: California has a moment of sanity, and a lawyer is furious,” Wall.St.J. (June 5, 2019).

[5]  Michael Waters, “The Secretive Non-Profit Gaming California’s Health Laws,” The Outline (June 18, 2018); Beth Mole, “The secretive nonprofit that made millions suing companies over cancer warnings,” Ars Technica (June 6, 2019); NAS, “Coffee with Cream, Sugar & a Dash of Acrylamide” (June 9, 2018); NAS, “The Council for Education & Research on Toxics” (July 9, 2013); NAS, “Sand in My Shoe – CERTainly” (June 17, 2014) (CERT briefs supported by fellow-travelers, testifying expert witnesses Jerrold Abraham, Richard W. Clapp, Ronald Crystal, David A. Eastmond, Arthur L. Frank, Robert J. Harrison, Ronald Melnick, Lee Newman, Stephen M. Rappaport, David Joseph Ross, and Janet Weiss, all without disclosing conflicts of interest).

[6]  Milward v. Acuity Specialty Products Group, Inc., 664 F. Supp. 2d 137, 148 (D.Mass. 2009), rev’d, 639 F.3d 11 (1st Cir. 2011), cert. den. sub nom. U.S. Steel Corp. v. Milward, 565 U.S. 1111 (2012), on remand, Milward v. Acuity Specialty Products Group, Inc., 969 F.Supp. 2d 101 (D.Mass. 2013) (excluding specific causation opinions as invalid; granting summary judgment), aff’d, 820 F.3d 469 (1st Cir. 2016).

[7]  NAS, “The Council for Education & Research on Toxics” (July 9, 2013) (CERT amicus brief filed without any disclosure of conflict of interest). The fellow travelers who knowingly or unknowingly aided CERT’s scheme to pervert the course of justice, included some well-known testifiers for the lawsuit industry: Nicholas A. Ashford, Nachman Brautbar, David C. Christiani, Richard W. Clapp, James Dahlgren, Devra Lee Davis, Malin Roy Dollinger, Brian G. Durie, David A. Eastmond, Arthur L. Frank, Frank H. Gardner, Peter L. Greenberg, Robert J. Harrison, Peter F. Infante, Philip J. Landrigan, Barry S. Levy, Melissa A. McDiarmid, Myron Mehlman, Ronald L. Melnick, Mark Nicas, David Ozonoff, Stephen M. Rappaport, David Rosner, Allan H. Smith, Daniel Thau Teitelbaum, Janet Weiss, and Luoping Zhang. See also NAS, “Carl Cranor’s Conflicted Jeremiad Against Daubert” (Sept. 23, 2018); Carl Cranor, “Milward v. Acuity Specialty Products: How the First Circuit Opened Courthouse Doors for Wronged Parties to Present Wider Range of Scientific Evidence” (July 25, 2011).

 

 

Toxicology for Judges – The New Reference Manual on Scientific Evidence (2011)

October 5th, 2011

I have begun to dip into the massive third edition of the Reference Manual on Scientific Evidence.  To date, there have been only a couple of acknowledgments of this new work, which was released to the public on September 28, 2011.  SeeA New Day – A New Edition of the Reference Manual of Scientific Evidence”; and David Kaye, “Prometheus Unbound: Releasing the New Edition of the FJC Reference Manual on Scientific Evidence.”

Like previous editions, the substantive scientific areas are covered in discrete chapters, written by subject matter specialists, often along with a lawyer who addresses the legal implications and judicial treatment of that subject matter.  From my perspective, the chapters on statistics, epidemiology, and toxicology are the most important in my practice and in teaching, and I decided to start with the toxicology.  The toxicology chapter, “Reference Guide on Toxicology,” in the third edition is written by Professor Bernard D. Goldstein, of the University of Pittsburgh Graduate School of Public Health, and Mary Sue Henifin, a partner in the law firm of Buchanan Ingersoll, P.C.

CONFLICTS OF INTEREST

At the question and answer session of the public release ceremony, one gentleman rose to note that some of the authors were lawyers with big firm affiliations, which he supposed must mean that they represent mostly defendants.  Based upon his premise, he asked what the review committee had done to ensure that conflicts of interest did not skew or distort the discussions in the affected chapters.  Dr. Kassirer and Judge Kessler responded by pointing out that the chapters were peer reviewed by outside reviewers, and reviewed by members of the supervising review committee.  The questioner seemed reassured, but now that I have looked at the toxicology chapter, I am not so sure.

The questioner’s premise that a member of a large firm will represent mostly defendants and thus have a pro-defense  bias is probably a common perception among unsophisticated lay observers.  What is missing from their analysis is the realization that although gatekeeping helps the defense lawyers’ clients, it takes away legal work from firms that represent defendants in the litigations that are pretermitted by effective judicial gatekeeping.  Erosion of gatekeeping concepts, however, inures to the benefit of plaintiffs, their counsel, as well as the expert witnesses engaged on behalf of plaintiffs in litigation.

The questioner’s supposition in the case of the toxicology chapter, however, is doubly flawed.  If he had known more about the authors, he would probably not have asked his question.  First, the lawyer author, Ms. Henifin, is known for having taken virulently anti-manufacturer positions.  See Richard M. Lynch and Mary S. Henifin, “Causation in Occupational Disease: Balancing Epidemiology, Law and Manufacturer Conduct,” 9 Risk: Health, Safety & Environment 259, 269 (1998) (conflating distinct causal and liability concepts, and arguing that legal and scientific causal criteria should be abrogated when manufacturing defendant has breached a duty of care).

As for the scientist author of the toxicology chapter, Professor Goldstein, the casual reader of the chapter may want to know that he has testified in any number of toxic tort cases, almost invariably on the plaintiffs’ side.  Unlike the defense lawyer, who loses business revenue, when courts shut down unreliable claims, plaintiffs’ testifying or consulting expert witnesses stand to gain by minimalist expert witness opinion gatekeeping.  Given the economic asymmetries, the reader must thus want to know that Prof. Goldstein was excluded as an expert witness in some high-profile toxic tort cases.  See, e.g., Parker v. Mobil Oil Corp., 7 N.Y.3d 434, 857 N.E.2d 1114, 824 N.Y.S.2d 584 (2006) (dismissing leukemia (AML) claim based upon claimed low-level benzene exposure from gasoline) , aff’g 16 A.D.3d 648 (App. Div. 2d Dep’t 2005).  No; you will not find the Parker case cited in the Manual‘s chapter on toxicology. (Parker is, however, cited in the chapter on exposure science.)

I have searched but I could not find any disclosure of Professor Goldstein’s conflicts of interests in this new edition of the Reference Manual.  I would welcome a correction if I am wrong.  Having pointed out this conflict, I would note that financial conflicts of interest are nothing really compared to ideological conflicts of interest, which often propel scientists into service as expert witnesses.

HORMESIS

One way that ideological conflicts might be revealed is to look for imbalances in the presentation of toxicologic concepts.  Most lawyers who litigate cases that involve exposure-response issues are familiar with the “linear no threshold” (LNT) concept that is used frequently in regulatory risk assessments, and which has metastasized to toxic tort litigation, where LNT often has no proper place.

LNT is a dubious assumption because it claims to “known” the dose response at very low exposure levels in the absence of data.  There is a thin plausibility for genotoxic chemicals claimed to be carcinogens, but even that plausibility evaporates when one realizes that there are defense and repair mechanisms to genotoxicity, which must first be saturated before there can be a carcinogenic response.  Hormesis is today an accepted concept that describes a dose-response relationship that shows a benefit at low doses, but harm at high doses.

The toxicology chapter in the Reference Manual has several references to LNT but none to hormesis.  That font of all knowledge, Wikipedia reports that hormesis is controversial, but so is LNT.  This is the sort of imbalance that may well reflect an ideological bias.

One of the leading textbooks on toxicology describes hormesis:

“There is considerable evidence to suggest that some non-nutritional toxic substances may also impart beneficial or stimulatory effects at low doses but that, at higher doses, they produce adverse effects. This concept of “hormesis” was first described for radiation effects but may also pertain to most chemical responses.”

Curtis D. Klaassen, Casarett & Doull’s Toxicology: The Basic Science of Poisons 23 (7th ed. 2008) (internal citations omitted).

Similarly, the Encyclopedia of Toxicology describes hormesis as an important phenomenon in toxicologic science:

“This type of dose–response relationship is observed in a phenomenon known as hormesis, with one explanation being that exposure to small amounts of a material can actually confer resistance to the agent before frank toxicity begins to appear following exposures to larger amounts.  However, analysis of the available mechanistic studies indicates that there is no single hormetic mechanism. In fact, there are numerous ways for biological systems to show hormetic-like biphasic dose–response relationship. Hormetic dose–response has emerged in recent years as a dose–response phenomenon of great interest in toxicology and risk assessment.”

Philip Wexler, Bethesda, et al., eds., 2 Encyclopedia of Toxicology 96 (2005).  One might think that hormesis would also be of great interest to federal judges, but they will not learn about it from reading the Reference Manual.

Hormesis research has come into its own.  The International Dose-Response Society, which “focus[es] on the dose-response in the low-dose zone,” publishes a journal, Dose-Response, and a newsletter, BELLE:  Biological Effects of Low Level Exposure.  In 2009, two leading researchers in the area of hormesis published a collection of important papers:  Mark P. Mattson and Edward J. Calabrese, eds., Hormesis: A Revolution in Biology, Toxicology and Medicine (N.Y. 2009).

A check in PubMed shows that LNT has more “hits” than “hormesis” or “hermetic,” but still the latter phrases exceed 1,267 references, hardly insubstantial.  In actuality, there are many more hermetic relationships identified in the scientific literature, which often fails to identify the relationship by the term hormesis or hermetic.  See Edward J. Calabrese and Robyn B. Blain, “The hormesis database: The occurrence of hormetic dose responses in the toxicological literature,” 61 Regulatory Toxicology and Pharmacology 73 (2011) (reviewing about 9,000 dose-response relationships for hormesis, to create a database of various aspects of hormesis).  See also Edward J. Calabrese and Robyn B. Blain, “The occurrence of hormetic dose responses in the toxicological literature, the hormesis database: An overview,” 202 Toxicol. & Applied Pharmacol. 289 (2005) (earlier effort to establish hormesis database).

The Reference Manual’s omission of hormesis is regrettable.  Its inclusion of references to LNT but not to hormesis appears to result from an ideological bias.

QUESTIONABLE SUBSTANTIVE OPINIONS

One would hope that the toxicology chapter would not put forward partisan substantive positions on issues that are currently the subject of active litigation.  Fondly we would hope that any substantive position advanced would at least be well documented.

For at least one issue, the toxicology chapter dashes our fondest hopes.  Table 1 in the chapter presents a “Sample of Selected Toxicological End Points and Examples of Agents of Concern in Humans.” No documentation or citations are provided for this table.  Most of the exposure agent/disease outcome relationships in the table are well accepted, but curiously at least one agent-disease pair is the subject of current litigation is wildly off the mark:

Parkinson’s disease and manganese

Reference Manual at 653.  If the chapter’s authors had looked, they would have found that Parkinson’s disease is almost universally accepted to have no known cause, except among a few plaintiffs’ litigation expert witnesses.  They would also have found that the issue has been addressed carefully and the claimed relationship or “concern” has been rejected by the leading researchers in the field (who have no litigation ties).  See, e.g., Karin Wirdefeldt, Hans-Olaf Adami, Philip Cole, Dimitrios Trichopoulos, and Jack Mandel, “Epidemiology and etiology of Parkinson’s disease: a review of the evidence.  26 European J. Epidemiol. S1, S20-21 (2011); Tomas R. Guilarte, “Manganese and Parkinson’s Disease: A Critical Review and New Findings,” 118 Environ Health Perspect. 1071, 1078 (2010) (“The available evidence from human and non­human primate studies using behavioral, neuroimaging, neurochemical, and neuropathological end points provides strong sup­port to the hypothesis that, although excess levels of [manganese] accumulation in the brain results in an atypical form of parkinsonism, this clini­cal outcome is not associated with the degen­eration of nigrostriatal dopaminergic neurons as is the case in PD.”)

WHEN ALL YOU HAVE IS A HAMMER, EVERYTHING LOOKS LIKE A NAIL

The substantive specialist author, Professor Goldstein, is not a physician; nor is he an epidemiologist.  His professional focus on animal and cell research shows, and biases the opinions offered in this chapter.

“In qualitative extrapolation, one can usually rely on the fact that a compound causing an effect in one mammalian species will cause it in another species. This is a basic principle of toxicology and pharmacology.  If a heavy metal, such as mercury, causes kidney toxicity in laboratory animals, it is highly likely to do so at some dose in humans.”

Reference Manual at 646.

Such extrapolations may make sense in regulatory contexts, where precauationary judgments are of interest, but they hardly can be said to be generally accepted in controversies in civil actions over actual causation.  Crystalline silica, for instance, causes something resembling lung cancer in rats, but not in mice, guinea pigs, or hamsters.  It hardly makes sense to ask juries to decide whether the plaintiff is more like a rat than a mouse.

For a sober second opinion to the toxicology chapter, one may consider the views of some well-known authors:

“Whereas the concordance was high between cancer-causing agents initially discovered in humans and positive results in animal studies (Tomatis et al., 1989; Wilbourn et al., 1984), the same could not be said for the reverse relationship: carcinogenic effects in animals frequently lacked concordance with overall patterns in human cancer incidence (Pastoor and Stevens, 2005).”

Hans-Olov Adami, Sir Colin L. Berry, Charles B. Breckenridge, Lewis L. Smith, James A. Swenberg, Dimitrios Trichopoulos, Noel S. Weiss, and Timothy P. Pastoor, “Toxicology and Epidemiology: Improving the Science with a Framework for Combining Toxicological and Epidemiological Evidence to Establish Causal Inference,” 122 Toxciological Sciences 223, 224 (2011).

Once again, there is a sense that the scholarship of the toxicology chapter is not as complete or thorough as we would hope.