Opinion ID: 184305
Heading Depth: 3
Heading Rank: 2

Heading: Proof of Specific Causation

Text: KBR next contends that the district court erred in finding that Clark had proved specific causation in this case, that is, that Clark’s benzene exposure while working at KBR caused his AML.5 It also argues the district court abused 2 Similarly, our decision in Johnson v. Cenac Towing Inc., 544 F.3d 296, 302 n.4 (5th Cir. 2008), does no more than note the content of Justice Souter’s concurrence; it does not adopt it or change the circuit’s law, nor, under the rule of orderliness, could it. 3 After oral argument, KBR filed a letter pursuant to Federal Rule of Appellate Procedure 28(j) alerting us to the Supreme Court’s recent grant of certiorari in McBride v. CSX Transportation, Inc., 598 F.3d 388 (7th Cir. 2010), cert. granted, No. 10-235 (U.S. Nov. 29, 2010). The Court’s statement of the question presented directly addresses the issue left open in Sorrell: “Whether [FELA] requires proof of proximate causation.” As discussed above, the standard of proof under the Jones Act is the same as the standard under FELA. See Ferguson, 352 U.S. at 523. Nevertheless, “[a]bsent an intervening Supreme Court case overruling prior precedent, we remain bound to follow our precedent even when the Supreme Court grants certiorari on an issue.” United States v. Lopez-Velasquez, 526 F.3d 804, 808 n.1 (5th Cir. 2008). We therefore continue to apply Gautreaux and Chisholm to the present case. 4 We thus disagree with KBR’s assertion that the district court’s finding of “no proximate cause” requires reversal in view of our discussion of the causation standard for Jones Act negligence cases. 5 “General causation is whether a substance is capable of causing a particular injury or condition in the general population, while specific causation is whether a substance caused a particular individual’s injury.” Knight v. Kirby Inland Marine Inc., 482 F.3d 347, 351 (5th Cir. 2007) (quoting Merrell Dow Pharms. v. Havner, 953 S.W.2d 706, 714 (Tex. 1997) (Owen, J.)). KBR does not appeal the district court’s finding of general causation. In this respect, this case differs markedly from the recent case of LeBlanc v. Chevron USA, Inc., No. 09-31149, 2010 U.S. App. LEXIS 19778 (5th Cir. Sept. 23, 2010) (unpublished), where the expert evidence did not support a conclusion that benzene was the general cause of the different disease there at issue. 6 Case: 09-41190 Document: 00511372672 Page: 7 Date Filed: 02/04/2011 No. 09-41190 its discretion in considering the testimony of Clark’s expert causation witnesses, which provided the evidentiary support for the district court’s conclusion. These two arguments are, taken together, an attack on Clark’s chain of proof of his exposure to benzene. It is perhaps simplest to identify KBR’s points of contention by first following the district court’s logic in concluding that Clark had adequately proved specific causation. As an initial matter, the district court found as fact that Clark was exposed to benzene while working on KBR’s barges. In so finding, the district court expressly credited the testimony of Clark himself and of Robert Biddle, a coworker of Clark’s. Clark testified that he used benzene as a solvent to clean his tools, hands, and equipment, and Biddle corroborated that benzene was present on KBR’s barges and was used regularly as a cleaning solvent. Biddle did not, however, testify that he ever observed Clark using benzene. Clark’s doctor, Dr. Deborah Thomas, also testified that Clark told her that he had been exposed to benzene while giving his medical history and before he saw a lawyer. KBR put on contrary witnesses who testified that there was no benzene on the company’s barges, but the district court concluded that Clark’s three fact witnesses were more credible and expressly credited their testimony as true. To the extent that KBR attempts to challenge the district court’s decision to credit Clark’s, Biddle’s, and Thomas’s testimony, we reject that challenge; under the already deferential clear error standard, the district court’s “[f]indings based on the credibility of witnesses demand even greater deference.” See Tokio Marine & Fire Ins. Co. v. FLORA M/V, 235 F.3d 963, 970 (5th Cir. 2001). The district court’s determination that Clark, Biddle, and Thomas testified truthfully is “plausible in light of the record viewed in its entirety” and surely a “permissible view of the evidence,” and we therefore are obliged to treat it as conclusive. See Anderson, 470 U.S. at 573–74. 7 Case: 09-41190 Document: 00511372672 Page: 8 Date Filed: 02/04/2011 No. 09-41190 Next, the district court looked to the parties’ respective expert testimony interpreting the fact witnesses’ statements concerning Clark’s exposure to benzene. Clark presented four expert witnesses: John Martonik, an industrial hygienist; Peter Infante, D.D.S., D.P.H., an epidemiologist; Frank Gardner, M.D., a hematologist and oncologist; and Frank Parker, an industrial hygienist. Martonik died between discovery and trial and so did not personally testify, but his pre-trial work was considered as evidence. KBR also presented the testimony of Robert Schumacher, an industrial hygienist. Martonik reviewed Clark’s deposition testimony and spoke with him on one occasion, then prepared a report attempting to identify the frequency, extent, and duration of Clark’s exposures to benzene. Martonik’s report can be said to serve two related but distinct purposes: first, it summarized Clark’s various exposures to benzene, and, second, it attempted to convert those exposures from Clark’s descriptions into quantifiable parts-per-million (“ppm”) exposure levels based on literature describing what exposure levels translate to particular reportable effects.6 While disagreeing with the precise resulting calculations, KBR’s expert, Schumacher, testified that Martonik’s approach was an “acceptable” and “generally accepted” means of determining an exposure level from self-reported information. Infante, Clark’s witness, and Schumacher, KBR’s witness, then attempted to extrapolate Clark’s total benzene exposure level from Martonik’s calculations. Each witness presented what the district court termed different “scenarios” for Clark’s total exposure based on different assumptions and readings of the evidence regarding the frequency, duration, and strength of Clark’s exposures to benzene. At the high end, Infante testified in his deposition that Clark’s 6 For example, Martonik’s report explained that “[t]he odor recognition threshold for benzene is 97 ppm”; therefore, it concluded that, whenever Clark was exposed to benzene that he could smell, he was exposed to no less a concentration than 97 ppm. 8 Case: 09-41190 Document: 00511372672 Page: 9 Date Filed: 02/04/2011 No. 09-41190 benzene exposure range could be between 1436 and 1532 ppm-years, and, at the low end, Schumacher testified to a benzene exposure level of 230 ppm-years. At trial, Infante revised his estimate downward to between 350 and 500 ppm-years. All of these various numbers were based, at bottom, on Clark’s testimony, which the district court credited fully, as bolstered by the testimony given by Biddle and Thomas. After trial, the district court accepted Infante’s findings in part, apparently rejecting only the contention “that benzene was present in the workplace to the extent the plaintiffs’ third party exposure witnesses suggested it was.” The court expressly did accept Clark’s own testimony about “the frequency and manner of” his exposure to benzene. Next, Gardner testified that his review of Clark’s testimony and the exposure data led him to conclude that Clark’s exposure to benzene while working for KBR caused his AML. Gardner also relied on undisputed literature that benzene is a known general cause of AML. Clark’s expert witnesses testified that the increase in relative risk of AML from benzene exposure was statistically significant at levels of exposure in the single digits of ppm-years; at the 230 ppm-years level calculated by KBR’s expert, Schumacher, Infante testified that the relative risk of AML was twenty-seven times higher than in the unexposed population. KBR did not rebut this quantification of risk. Thus, even using the most conservative numbers supported by the factual evidence the district court credited, the exposure numbers at issue in this case are very high. The court accepted Clark’s testimony that he used benzene every other day from somewhere between fifteen minutes and a few hours from 1972 until sometime the late 1970s. The court accepted Clark’s testimony that he did not use protective equipment when working with benzene and occasionally felt lightheaded from exposure. Taking that evidence together with the experts’ testimony correlating symptoms with particular exposure levels and identifying the relatively low exposure levels known to be hazardous, the district court 9 Case: 09-41190 Document: 00511372672 Page: 10 Date Filed: 02/04/2011 No. 09-41190 found that “it is more likely than not that Mr. Clark was exposed to benzene at hazardous levels.” That finding is eminently “plausible in light of the record viewed in its entirety,” and we therefore must uphold it. See Anderson, 470 U.S. at 573–74. KBR’s contrary argument, citing to our decision in Allen v. Pennsylvania Engineering Corp., 102 F.3d 194, 199 (5th Cir. 1996), is essentially that Gardner was required to quantify precisely the dosage of benzene that is hazardous and the dosage of benzene to which Clark was exposed before he could lawfully be permitted to testify, and similarly that the district court was required to make those same determinations before it could find specific causation. Because Gardner did not do so, KBR reasoned, admission of his testimony was an abuse of discretion and there was no evidence upon which the district court could permissibly rely in finding specific causation. Our precedent has no such requirement. In Allen, we stated the uncontroversial principle that “[s]cientific 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.” Id. Here, Clark did meet this burden: Gardner and other witnesses testified to the toxic levels of benzene exposure, and both Gardner and the court had sufficient factual evidence to conclude that Clark was exposed to some level of benzene high enough to cause AML. While the district court did not credit that Clark was exposed to as much benzene as Infante concluded, even a much lower number, well supported by the evidence the district court did credit, was acknowledged by the experts to be sufficient to have caused Clark’s AML. Gardner’s methodology remained “reliable,” and his testimony remained useful to “assist the trier of fact to understand the evidence.” See F ED. R. E VID. 702. Assisted by the testimony that Gardner gave, the district court could evaluate the exposure evidence and conclude, without committing clear error, that, even if he was exposed to 10 Case: 09-41190 Document: 00511372672 Page: 11 Date Filed: 02/04/2011 No. 09-41190 somewhat less benzene than Infante originally suggested, Clark was exposed to a level of benzene known to the scientific community to substantially and significantly increase the risk of AML. We find no abuse of discretion in the district court’s decision to admit Clark’s expert witnesses’ testimony—notwithstanding its refusal to wholly credit their assessment of the extent of Clark’s benzene exposure—and no clear error in the district court’s finding of specific causation.7