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December 18, 2020

Environmental, Natural Resources, & Energy Law Blog

“Chasing the Science” Can Plaintiffs’ Personal Injury PFAS MDL survive summary judgment? - Marie Napoli

This paper will examine the history of PFAS and the litigation before Judge Gergel, in South Carolina Federal District Court, and analyze the fate of environmental personal injury torts, on a mass tort basis, in light of causation issues anticipated under Daubert analysis with Lipitor (pharmaceutical) MDL jurisprudence. Specifically, it will analyze Justice Gergle’s standard of review, and propose a narrow path to personal injury claims’ survival on a summary judgment motion, despite the conservative Judge’s tendency to replace the experts’ opinions for his own. It will also submit that even if plaintiffs are unable to thread the needle and prove causation in a manner that is admissible under Daubert, when motions to dismiss are made a second bite of the apple will be possible through motions to vacate and reargue, once enough information can be gathered through a medical monitoring class to prove causation legally speaking. Hopefully at that time, if years later, Judge Gergle, who dismisses over 80 percent of his cases on summary judgment, will be off the bench, and a liberal appointment under Biden will prove to have a more compassionate legal analysis for the millions suffering due to corporate wonton greed.


PFAS Overview

Perfluorooctanoic acid (“PFOA”) and perfluorooctane sulfonate (“PFOS”) (collectively “PFAS”) are part of a group of man-made perfluorinated chemicals. PFAS have been manufactured and used in a variety of industries since the 1940s but were not widely documented until the early 2000s. These “emerging contaminants” are found in products ranging from non-stick cookware to firefighting foam and have been found to contaminate sites and drinking water systems across the country. Due to the chemical nature of PFOA and PFOS as a surfactant, it was able to be mixed with water and sprayed as foam on fires, putting a film on the fire to separate oxygen from the fuel surface, and therefore able to stop the chemical reaction from burning. This firefighting foam, or Aqueous Film Forming Foam (“AFFF”) was widely used particularly at municipal airports and military bases for training purposes and to combat jet fuel spills. The foam seeped through the soil at these sites and, through migration and runoff, leached into underground aquifers and surface water bodies used for drinking water.

PFOA was produced by eight major U.S. companies, including: Arkema, Asahi, Ciba, Clariant, Daikin, DuPont, 3M/Dyneon, Solvay, and Solexis. PFOS was solely produced by one company in the United States: 3M Company. Although these manufacturers agreed to phase-out AFFF containing PFAS several years ago, recent testing has led to the discovery of widespread contamination in drinking water supplies throughout the country.

The MDL Litigation:

The first lawsuits brought against the manufacturers and distributors of AFFF were filed in 2016. In 2018, the Judicial Panel for Multidistrict Litigation consolidated these lawsuits into a single action in the District of South Carolina before Judge Richard Gergel. See In Re: Aqueous Film-Forming Foams Products Liability Litigation, MDL No. 2:18-mn-2873-RMG (D.S.C.). Since then, approximately two hundred cases have either been filed in or transferred to the coordinated MDL proceedings before Judge Gergel, all of which involve allegations by plaintiffs that PFAS contaminated groundwater near various military bases, airports, and other industrial sites where AFFFs were used to extinguish liquid fuel fires. Additional cases are expected to be filed or transferred to the MDL in the coming months.

Shortly after it was established, Judge Gergel approved a leadership structure for the MDL, which included appointing Paul J. Napoli from Napoli Shkolnik PLLC. The cases in the MDL involve a variety of plaintiffs and claims, including class actions brought on behalf of residents in areas where PFAS contamination occurred, lawsuits involving individual personal injury claims, and actions brought on behalf of states, municipalities, and public water districts for costs associated with treating contaminated water systems.

Judge Gergel’s Causation Analysis in the Lipitor MDL

Judge Gergel’s Lipitor opinions are a useful predictor of how he will approach his causation analysis in the AFFF cases, discussed more in depth below. Knowing how Judge Gergel ruled in the Lipitor MDL can help us better assess the issues likely to arise, the evidence needed, and the importance of a medical monitoring program to help prove actual causation.


A. General Causation Ruling (CMO 68)

Plaintiffs designated four experts—Sonal Singh, M.D., M.P.H.; Michael Quon, M.D.; Barbara Roberts, M.D.; and William Gale, M.D.—to opine that Lipitor caused Type 2 diabetes in the general population. Importantly, while the experts initially opined that Lipitor caused diabetes without any reference to dose, Judge Gergel later ordered them to submit supplemental reports that included causation opinions specific to each of the available Lipitor doses (10 mg, 20 mg, 40 mg, and 80 mg). Following another round of depositions, briefing, and argument, Judge Gergel issued an opinion excluding all but one of the dose-specific causation opinions proffered by plaintiffs’ experts.

For our purposes, it is useful to focus on Judge Gergel’s analysis of the opinions proffered by two of plaintiffs’ general causation experts.[1] The first is Dr. Sonal Singh, an internist and trained epidemiologist from Johns Hopkins University who represented plaintiffs’ best hope of surviving a Daubert challenge. The second is Dr. Michael Quon, an endocrinologist at the University of Maryland School of Medicine and the author of a study assessing the relationship between Lipitor use and insulin resistance.

Starting with Dr. Singh, while Judge Gergel found his 80 mg opinion satisfied Daubert,[2] he excluded his causation opinions at the 10, 20, and 40 mg Lipitor doses. Regarding the 10 mg dose, Judge Gergel held that the “Bradford Hill method of proving causation” required evidence of a statistically significant association, which Dr. Singh could not provide because there were no studies reporting a statistically significant increased risk of diabetes at that dose. In re Lipitor, 174 F. Supp. 2d at 924–26. Judge Gergel also dismissed as unreliable Dr. Singh’s use of “non-statistically significant trends” to support his 10 mg opinion. Specifically, he pointed to plaintiffs’ failure to demonstrate that this approach had been “accepted in his field,” had “served as the basis for any epidemiologist’s causation opinion in peer-reviewed literature,” or that “standards exist[ed] for controlling the technique’s operation.” Id. at 926.

Judge Gergel also rejected Dr. Singh’s 20 and 40 mg opinions as unreliable. This conclusion was based principally on Dr. Singh’s testimony that his 20 and 40 mg opinions were “an inference based on the fact that Lipitor 10 mg and Lipitor 80 mg causes diabetes.” Id. at 927. Having already rejected his 10 mg opinion, Judge Gergel held that “Dr. Singh, by his own testimony, [was] unable to offer a causation opinion regarding Lipitor 20 mg or Lipitor 40 mg.” Id.

Turning to Dr. Quon, Judge Gergel excluded his opinions based on concerns about the reliability of the methodology he used. Chief among those was Dr. Quon’s failure to describe his methodology in either of his expert reports, as it was not until his deposition that he described the method he used as a “literature review.” Id. at 927 & n.17. Still, Judge Gergel chose to give Dr. Quon the benefit of the doubt and turned his focus to whether the specific literature review Dr. Quon performed was itself reliable. He concluded it was not for two reasons.

First, Judge Gergel determined Dr. Quon engaged in the type of “cherry-picking of data” that “fails to satisfy the scientific method and Daubert.” Id. at 930–32. He explained that this cherry-picking meant Dr. Quon failed to account for evidence contrary to his conclusion, which was indicative of a methodology that was “not reliable or scientifically sound.” Id. at 932–33. Second, Judge Gergel pointed to Dr. Quon’s failure to consider studies addressed in an earlier review article he co-authored that was published in a peer-reviewed medical journal. Id. at 930–31. According to Judge Gergel, the conflicting approach taken in his review article showed that Dr. Quon failed to employ “the same level of intellectual rigor in reaching his conclusions in this case as characterizes his practice in the field.” Id. at 933.

B. Specific Causation Rulings (CMOs 55 & 76)

Judge Gergel also ruled on Daubert motions challenging the opinions of two of plaintiffs’ specific causation experts: Elizabeth Murphy, M.D., PhD, a practicing endocrinologist, and David Handshoe, M.D., a practicing internist. Both experts claimed they used the differential diagnosis methodology—which identifies the cause of a medical problem by eliminating the likely causes until the most probable one is isolated—to conclude Lipitor caused an individual plaintiff’s diabetes. Acknowledging that differential diagnosis has long been recognized as a valid methodology for specific causation, Judge Gergel focused his analysis instead on whether Dr. Murphy and Dr. Handshoe reliably applied that methodology to the plaintiffs in their cases.

Citing the Reference Manual on Scientific Evidence, Judge Gergel began his analysis by drawing a distinction between cases involving relative risks between 1.0 and 2.0 and those involving a relative risk of 2.0 or greater. Where the existing evidence showed a “doubling of the risk,” Judge Gergel held plaintiffs could satisfy their specific causation burden with expert testimony that simply applied the Bradford-Hill criteria to the association at issue.[3] In re Lipitor (Daniels v. Pfizer) (“Daniels”), 185 F. Supp. 3d 786, 791–92 (D.S.C. 2016); In re Lipitor Mktg., Sales Practices & Prods. Liab. Litig. (Hempstead v. Pfizer) (“Hempstead”), 150 F. Supp. 3d 644, 649–50 (D.S.C. 2015). Conversely, Judge Gergel ruled that application of the Bradford-Hill criteria was not enough where the relative risk was between 1.0 and 2.0 because a “risk ratio in this range suggests that while some people exposed to the substance developed the disease due to the exposure, most would have developed the disease anyway.” Daniels, 185 F. Supp. 3d at 791; Hempstead, 150 F. Supp. 3d at 650.

Because their relative risk estimates were between 1.0 and 2.0, Judge Gergel believed the critical question was how Dr. Murphy and Dr. Handshoe concluded their respective plaintiff was in the minority of Lipitor users that developed diabetes due to the medication and not for some other reason. Daniels, 185 F. Supp. 3d at 792; Hempstead, 150 F. Supp. 3d at 651. He concluded they failed to provide a satisfactory answer to that question for two reasons.

First, Judge Gergel relied on Dr. Murphy’s and Dr. Handshoe’s deposition testimony to conclude their opinions were premised almost exclusively on temporality. See Daniels, 185 F. Supp. 3d at 796 (finding Dr. Handshoe admitted his methodology was “solely based on the temporal relationship of developing diabetes after taking a statin”); Hempstead, 150 F. Supp. 3d at 653 (finding Dr. Murphy had “verified her exclusive reliance on a temporal relationship”). He explained that courts had overwhelmingly rejected this approach as unreliable and claimed it was particularly illogical where Dr. Murphy’s and Dr. Handshoe’s own relative risk estimates indicated most Lipitor patients developed diabetes for reasons other than the medication. Daniels, 185 F. Supp. 3d at 796–801; Hempstead, 150 F. Supp. 3d at 657–61.

Second, Judge Gergel determined that Dr. Murphy and Dr. Handshoe failed to adequately address their respective plaintiffs’ other risk factors for diabetes. Although he acknowledged that experts need not rule out every alternative cause, Judge Gergel held that, at a minimum, a reliable differential diagnosis required “an explanation as to why these other recognized causes, alone, are not responsible for the disease in a particular plaintiff.” Daniels, 185 F. Supp. 3d at 800; Hempstead, 150 F. Supp. 3d at 661. According to Judge Gergel, Dr. Murphy failed to satisfy this requirement because she simply claimed all of the plaintiff’s risk factors contributed to their diabetes, Hempstead, 150 F. Supp. 3d at 654–57, while Dr. Handshoe’s use of his “clinical judgment” to eliminate risk factors, without further explanation, amounted to nothing more than “unacceptable ipse dixit.” Id. at 807.

How Plaintiffs Can Prevail on Causation in the AFFF MDL

Although Judge Gergel set a high bar for establishing causation in the Lipitor MDL, there are ways that plaintiffs can avoid suffering a similar fate in the AFFF MDL. For one thing, although the Fourth Circuit later upheld Judge Gergel’s general causation rulings, its opinion mitigated some of the more extreme aspects of his analysis. For example, although it upheld Judge Gergel’s order requiring dose-specific causation opinions, the court made clear this was not a universal requirement that applied in every case.[4] In re Lipitor, 892 F.3d 624, 640 (4th Cir. 2018) (“The appropriate level of [dosage] analysis will depend on the circumstances of the case and the capacity of current scientific methods.”). Likewise, the Fourth Circuit expressly declined to establish a “bright-line rule requiring experts to rely only on evidence that is statistically significant or else have their opinions excluded,” reasoning that the “record, literature, and case law make clear that statistical significance, while important in many contexts, doesn’t always paint a full portrait.” Id. at 642.


But while these passages from the Fourth Circuit’s opinion are helpful, they are unlikely to change the outcome for plaintiffs in the AFFF MDL on their own. For this reason, it is imperative that the AFFF plaintiffs use all available means to develop support for future expert testimony addressing general and specific causation.

Despite the high bar Judge Gergel set for causation issues, medical monitoring is another important claim we can assert for the PFAS MDL cases. We are awaiting health effect developments over time, as we do not have all the evidence given the newfound knowledge on this dangerous chemical. Judge Gergel, in the AFFF MFL, plans to address medical monitoring even before we get to the personal injury claims because he himself recognizes the science needs more time to develop. In Jack W. Leach, et al. v. E.I. du Pont de Nemours & Company (no. 01-C-608 W.Va., Wood County Circuit Court, filed 10 April 2002), part of the settlement which stemmed from the PFOA contamination of drinking water, provided for a medical monitoring program. There, The C8 Health Project was created, authorized, and funded as part of the settlement agreement in which data from medical monitoring was eventually used to link PFOA exposure to various injuries. In the AFFF MDL, we are doing the same by pursuing medical monitoring to see different health outcomes of those exposed over time. This in turn will give us evidence that we can use as a weapon in the fight to prove and establish actual causation.


[1] Notwithstanding Judge Gergel’s order, Dr. Roberts failed to provide dose-specific opinions in her supplemental report and Dr. Gale failed to submit a supplemental report altogether. See In re Lipitor Mktg., Sales Practices & Prods. Liab. Litig.(“In re Lipitor”), 174. F. Supp. 3d 911, 933 (D.S.C. 2016).

[2] Judge Gergel concluded that Dr. Singh’s opinion satisfied Daubert for two reasons. First, he agreed with plaintiffs that studies existed reporting a statistically significant increased risk of diabetes in patients taking 80 mg Lipitor. In re Lipitor, 174 F. Supp. 3d at 922. Second, he determined that Dr. Singh reliably applied the Bradford-Hill criteria to conclude that Lipitor caused diabetes at that dose. Id.

[3] Judge Gergel reasoned that a doubling of risk connoted a greater than 50% chance the substance caused the plaintiff’s injury, which was “the equivalent of the required legal burden of proof—a showing of causation by the preponderance of the evidence.” Daniels, 185 F. Supp 3d at 791; Hempstead, 150 F. Supp. 3d at 650.

[4] The court also singled out pharmaceutical cases as “lend[ing] themselves quite well to dosage analysis” because medications are “typically prescribed and consumed in measured and knowable quantities,” In re Lipitor, 892 F.3d at 639, a characteristic that does not apply in cases involving exposure to AFFF.