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Expert’s Specific Causation Methodology Unreliable in Leukemia Row

In a case underscoring the importance of reliable methodologies in expert testimony, the U.S. Court of Appeals for the First Circuit upheld a trial court decision excluding specific causation testimony linking benzene exposure and acute promyelocytic leukemia (“APL”) because the expert could not properly support her conclusions.  See Milward v. Rust-Oleum Corp., No. 13-2132, 2016 WL 1622620 (1st Cir. Apr. 25, 2016).

Plaintiff alleged he was exposed to benzene from Defendant’s products during his work as a pipefitter and refrigerator technician, and that such exposures caused his APL. To support this contention, Plaintiff relied on the testimony of Dr. Sheila Butler, a physician specializing in occupational chemical exposures. The trial court found Dr. Butler’s methodologies unreliable and excluded her causation testimony under Rule 702.  With Plaintiff unable to show specific causation, the trial court granted a defense motion for summary judgment. 

On appeal, Plaintiff challenged the trial court’s treatment of Dr. Butler’s relative risk analysis and differential diagnosis, and the First Circuit upheld the trial court’s decision.  In her relative risk analysis, Dr. Butler compared Plaintiff’s benzene exposure levels to those that had been found to be dangerous in other studies.  The Court found, however, that Dr. Butler had not accounted for studies that conflicted with her opinion, nor could she explain why she chose the studies she chose.  Dr. Butler’s “complete unwillingness to engage with the conflicting studies (irrespective of whether she was able to or not) made it impossible for the district court to ensure that her opinion was actually based on scientifically reliable evidence . . . .”  Id. at *13.  The First Circuit found this lack of reliability justified the trial court’s exclusion of her testimony.

The First Circuit also found Dr. Butler’s differential diagnosis unreliable.  Dr. Butler ruled out all other causal factors associated with APL, including smoking, obesity, and idiopathic diagnosis (i.e. a diagnosis with no known cause).  The Court noted that Dr. Butler only “ruled out” idiopathic causes because she “ruled in” benzene as a cause of Plaintiff’s APL.  The Court found that because the record did not contain a scientifically reliable basis to “rule in” benzene, Dr. Butler’s dismissal of idiopathic causes was also unreliable. Therefore, while differential diagnosis can be a reliable methodology for showing specific causation, the First Circuit held that it was not reliably employed and upheld the trial court’s decision excluding Dr. Butler’s specific causation testimony.

© 2021 Beveridge & Diamond PC National Law Review, Volume VI, Number 146

About this Author

Graham C. Zorn Environmental, Toxic Tort, Products Liability Litigation Attorney Beveridge & Diamond Washington, DC

Graham Zorn focuses his practice on environmental, toxic tort, and products liability litigation.

His representative experience includes extensive work on a series of complex products liability and toxic tort cases related to alleged groundwater, and litigation over lead in drinking water. He has represented individual businesses, trade associations, and municipalities in litigation, as well as in compliance, enforcement, and counseling matters involving the Clean Air Act, the Clean Water Act, CERCLA and other state and federal environmental statutes. He also counsels domestic and...

Daniel M. Krainin Environmental Litigation Attorney Beveridge & Diamond New York, NY

Dan deploys more than two decades of environmental litigation experience to resolve clients’ legal and business challenges.

Primarily focused on environmental and toxic tort litigation, Dan helps clients successfully resolve groundwater contamination, hazardous waste site remediation, natural resource damages, permit defense and product-related matters. He enjoys using his skills as a litigator to help clients solve environmental problems.

Among his many wins, Dan successfully led a team that defeated an emergency challenge to a permit that Dan’s client needed to continue its...

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Eric L. Klein Environmental Litigation Attorney Beveridge & Diamond Boston, MA

Eric makes complex subjects simpler.

He is an environmental litigator in the Boston office of Beveridge & Diamond, with a national practice representing major companies and municipalities in a wide variety of matters including environmental and mass torts, class actions, and federal citizen suits under environmental statutes including the Clean Water Act, the Safe Drinking Water Act, and the Clean Air Act. He has handled cases in state and federal courts throughout the United States, litigating complex civil and commercial matters before juries, trial and appellate courts,...