“Not the Stuff of Science”: “Differential Etiology” Causation Opinions Fail Daubert in 7th Circuit Toxic Tort Case

The Seventh Circuit Court of Appeals has affirmed a district court’s grant of summary judgment in an environmental toxic tort case, holding that the testimony of all three of plaintiffs’ causation experts – James Dahlgren, M.D., Vera Byers, M.D., Ph.D, and Jill Ryer-Powder, Ph.D – was properly excluded as unreliable under the Daubert standard governing the admissibility of expert testimony.

In C.W. et al. v. Textron, Inc. (August 26, 2015; Court of Appeals Case No. 14-3448 (N.D. Ind.)), the plaintiffs were two minors whose parents filed tort claims on their behalf against Textron. While living near a Textron fastener manufacturing plant in Rochester, Indiana, the infant children experienced gastrointestinal, immunological, and neurological issues. The parents eventually learned that the groundwater well at their home was contaminated by vinyl chloride released from the Textron facility, at levels of five to nine parts per billion. The family moved out of the home and sued Textron, alleging that the company had exposed the children to vinyl chloride, which caused their illnesses and substantially increased their risk of cancer and other adverse health effects.

After four years of litigation, the district court granted in its entirety a motion in limine to exclude plaintiffs’ three expert witnesses and then granted summary judgment, finding that plaintiffs could not prove general or specific causation without the experts. The Court of Appeals affirmed, holding that the district court “properly adhered to the Daubert framework” and conducted an “exhaustive” review.

Dr. James Dahlgren testified that exposure to vinyl chloride can cause and did cause the children’s illnesses, and that it was highly likely that both children will develop cancer at some point in the future. The district court found that Dahlgren’s reliance on “differential etiology” (often mistakenly called “differential diagnosis”) failed to meet the Daubert standard, in part because Dahlgren “failed to connect the dots between the scientific studies that he analyzed and the opinions that he offered”: the studies that he relied upon failed to establish that vinyl chloride, at the dose and duration relevant to the case, could cause the problems that plaintiffs experienced or claimed they were likely to experience. The Court of Appeals agreed that Dahlgren’s methodology was unreliable, stating: “This approach is not the stuff of science.”

Dr. Vera Byers also testified that exposure to vinyl chloride – via contaminated drinking water, inhalation of vapors from bathing, and dermal contact – can cause and did cause the children’s gastrointestinal and immune-system problems. The district court similarly excluded her differential etiology testimony, finding the studies she relied on were not relevant, and there was no basis for “ruling in” vinyl chloride exposure as a possible cause of the medical issues. The Court of Appeals concurred, commenting: “Without the benefit of analogous studies and an acceptable method of extrapolation, Dr. Byers . . . is forced to take a leap of faith in pointing to vinyl chloride as having the capacity to cause the injuries (and risk of injury) to [plaintiffs]. The district court ably performed its gatekeeper role in shielding the jury from this leap.”

Dr. Jill Ryer-Powder testified similarly, relying on studies at much higher exposure levels than were present in the case. In forming her opinion on causation, Ryer-Powder also relied on the fact that the plaintiffs’ drinking water exceeded regulatory standards. As with Dr. Dahlgren and Dr. Byers, the district court found that she did not offer a reliable basis to support her opinion. The Court of Appeals held that the district court did not abuse its discretion in rejecting Ryer-Powder’s methodology, noting in part that exceedances of regulatory standards do not prove causation.

The Court of Appeals also:

• ruled that the district court properly rejected the experts’ methodology, to the extent they based their opinions on the timing of the plaintiffs’ injuries coinciding with their exposure to vinyl chloride (citing a prior Seventh Circuit opinion holding that the “mere existence of a temporal relationship” does not “show a sufficient causal relationship”); and 
• rejected plaintiffs’ claim that, because there are no studies available regarding the impact of vinyl chloride on children at the dose and duration in question, the experts’ testimony should have been admitted. The Court noted that computer-based models can extrapolate from animal data to human subjects, and from high doses to low doses, but plaintiffs’ experts did not mention or refer to this method of bridging the data gap.

Finally, the Court of Appeals affirmed the district court’s grant of summary judgment in the absence of any admissible expert causation evidence, but disagreed with that court’s categorical exclusion of  differential etiology as a method to establish general causation. The Court adopted the approach taken by the Second Circuit Court of Appeals in Ruggiero v. Warner-Lambert Co., 424 F.3d 249 (2005), recognizing that there may be instances where a rigorous use of differential etiology is sufficient to support an expert’s opinion on both general and specific causation.

-- Don Sobelman

For more information, contact Don Sobelman at (415) 228-5456 or des@bcltlaw.com