A federal judge has issued an opinion explaining her Daubert and summary judgment rulings in a case brought by a consumer who alleged he contracted lung disease from the fumes of microwave popcorn. Newkirk et al. v. ConAgra Foods Inc., No. 2:08-cv-00273 (E.D. Wash. 7/2/2010).

Readers of MassTortDefense may be familiar with the so-called “popcorn lung” litigation in which plaintiffs have alleged they contracted a series of diseases, including Bronchiolitis obliterans, from inhaling the chemical diacetyl which had been used in the artificial butter on microwave popcorn.  Most of the claims have been made by workers with alleged industrial-level exposures on a daily basis in popcorn factories several years ago.  There are, however, a handful of cases by consumers claiming they somehow had sufficient exposure in their homes to have the same respiratory injuries.  These latter cases raise significant issues of general and specific causation, arising from the central tenet of toxicology: the dose makes the poison.  The studies relied on by plaintiffs noted that the cumulative exposure to diacetyl was correlated with chronic effects on lung function in plant workers.

Plaintiff Newkirk claimed that the natural and artificial butter flavoring in ConAgra’s Act II Butter and Act II Butter Lovers popcorn products caused him severe and progressive damage to the respiratory system, extreme shortness of breath, and reduced life expectancy.  He claimed that he ate between five and seven bags of ConAgra’s popcorn every day for more than a decade.

The motions centered around plaintiff’s burden to prove causation. Plaintiffs in toxic tort cases must establish both general and specific causation. Golden v. CH2M Hill Hanford Group, Inc., 528 F.3d 681, 683 (9th Cir.2008). Evidence supporting general causation addresses “whether the substance at issue had the capacity to cause the harm alleged.” In re Hanford Nuclear Reservation Litigation, 292 F.3d 1124, 1133 (9th Cir.2002). Specific causation, by contrast, concerns whether a particular individual suffers from a particular ailment as a result of exposure to the substance. Defendants challenged plaintiff’s proof of both under Daubert.

Plaintiffs retained Dr. Egilman to offer an opinion on general causation, as well as to examine Mr. Newkirk, diagnose him, and offer an opinion regarding the specific cause of his condition. The expert opinion testimony of Dr. Egilman was the plaintiffs’ primary evidence supporting general causation. (All of the Newkirks’ other causation expert witnesses assumed that general causation already has been established.)  He opined that,  “There is no known safe level of diacetyl exposure. Existing scientific studies also suggest that levels of diacetyl exposure below and around 1 ppm can cause BO and other respiratory illnesses.”

The court found, however, that Dr. Egilman’s attempt to analogize kitchen to industrial exposures failed. He offered no sufficient basis or methodology for support for the conclusion that there is no important (medically relevant) qualitative difference between the vapor from butter flavoring slurry in a mixing vat in a popcorn plant and the vapor from butter flavoring that is emitted from microwave popcorn in the home. There was nothing to support Dr. Egilman’s conclusions that were at the heart of this case: that the vapors emitted from a microwave popcorn bag contain the same proportion of chemicals or in sufficient doses or that all of the substances in the two instances are identical. In other parts of his reports and testimony, the court found, Dr. Egilman relied on some existing data, mostly in the form of published studies, but drew conclusions far beyond what the study authors concluded.

Or, Dr. Egilman manipulated the data from those studies to reach misleading conclusions of his own. Slip opin. at 25. For example, he relied on statements by a Dr. Cecile Rose, on a patient (and another consumer plaintiff), Mr. Watson, who allegedly contracted disease from popcorn fumes. But this was in the nature of a single case report, and in it even Dr. Rose did not assert that her conclusions could be extrapolated to other consumers in the absence of publication or peer review; Dr. Egilman acknowledged that Dr. Rose did not publish the exposure levels measured in Mr. Watson’s home — so no such comparison was possible.  Dr. Rose herself qualified her conclusions: “It is difficult to make a causal connection based on a single case report. We cannot be sure that this patient’s exposure to butter flavored microwave popcorn from daily heavy preparation has caused his lung disease.”

The expert also relied on testing conducted by Dr. John Martyny in a kitchen (not of a consumer), despite that doctor’s own reflections that the methodology underlying the work could not support extrapolating to general causation for a broader group of consumers.  The expert also relied on animal studies. Expert opinion relying on animal studies to reach an opinion on causation in humans is usually admissible only when the expert explains how and why the results of the animal toxicological study can reliably be extrapolated to humans. General Electric Co. v. Joiner, 522 U.S. 136, 143-45 (1997).  Dr. Egilman offered no such analytical bridge between the animal studies finding harm from high levels of diacetyl exposure to lab rats and his conclusion that those studies demonstrate that diacetyl exposure causes decreased lung function in humans. He offered no sufficient explanation for how and why the results of those studies could be extrapolated to humans, let alone low-dose consumer contexts.

Without Dr. Egilman’s testimony to support causation, the plaintiffs’ other expert witnesses couldn’t establish this element either.

Note also that the court excluded Dr. Egilman’s “legal conclusions” from his expert report and affidavits, since the witness was no more capable than the fact-finder to draw such a conclusion. See Nationwide Transp. Fin. v. Cass Info. Sys., 523 F.3d 1051, 1059-60 (9th Cir.2008) (expert witness cannot give an opinion as to her legal conclusion, i.e., an opinion on an ultimate issue of law). For example, Dr. Egilman tried to opine that about what the defendant “knew” and “failed to warn” consumers. This is another useful precedent against plaintiffs’ mis-use of the conduct “expert” who provides mere legal conclusions and invades the province of the jury.

(Your humble blogger is involved in the diacetyl litigation, but not this case.)