A federal court has excluded plaintiffs’ expert testimony in litigation alleging personal injury and property damage from releases at a Midwest refinery. Baker, et al. v. Chevron USA Inc., et al., No. 05-cv-00227 (S.D. Ohio Jan. 6, 2010). In the absence of necessary expert testimony, the claims were subject to summary judgment.
Plaintiffs in this case were residents of the villages of Hooven and Cleves, Ohio, who asserted claims for personal injury and property damage allegedly resulting from the Gulf Oil refinery, now owned by defendant Chevron USA. Gulf operated a gasoline refinery which was situated on the eastern edge of Hooven from 1930 to 1985. Gulf also refined diesel fuel, jet fuel, and fuel oil at the refinery and operated an asphalt plant at this location. Gulf and Chevron merged in 1985, and Chevron closed the refinery in 1986.
Plaintiffs alleged that Gulf’s operation of the refinery resulted in the release of millions of gallons of gasoline and diesel fuel. But these plaintiffs did not claim injuries resulting from groundwater contamination. Rather, they asserted injuries allegedly caused by air emissions from the refinery and, in particular, the benzene contained in those emissions. Benzene is ubiquitous in the ambient air and is a component or constituent of vehicle exhaust and cigarette smoke. In the petroleum industry, benzene is found in small amounts in gasoline.
For case management purposes, the matter was bifurcated between personal injury claimants and property damage claimants. The parties were permitted to select bellwether plaintiffs for each trial group. This opinion dealt with the claims of the bellwether personal injury claimants, and a key issue, as is often the case in toxic tort litigation, was causation.
Regarding their alleged benzene exposure, plaintiffs offered a three-step procedure. First, expert Dr. Cheremisinoff calculated a gross amount of benzene released from the refinery through emissions. Then, using those calculations, Dr. Rosenfeld, plaintiffs’ second expert, used an air flow model to calculate the cumulative dose of benzene to which each plaintiff was exposed. Third, using those dose estimates, a third expert, Dr. Dahlgren, submitted opinions that each plaintiff’s dose of benzene was sufficient to cause her illness.
Chevron moved to exclude Dr. Dahlgren’s opinions under Daubert, and for summary judgment contingent upon the striking of plaintiffs’ causation evidence. The principal argument raised was that Dr. Dahlgren’s opinions were unreliable because there was an insufficient scientific or medical basis to conclude that the doses of benzene to which plaintiffs’ were exposed were large enough to have caused their illnesses. Relatedly, Chevron contended that there is an insufficient scientific or medical basis to conclude that benzene even causes some of the illnesses alleged. The Court held a hearing on Chevron’s Daubert motion during which Dr. Dahlgren and Chevron’s medical expert also testified.
In a toxic tort case, the plaintiff must present evidence of both general causation and specific causation. General causation establishes whether the substance or chemical at issue is capable of causing a particular injury or condition. Specific causation relates to whether the substance or chemical in fact caused this plaintiff’s medical condition. Without expert medical testimony on both general causation and specific causation, a plaintiff’s toxic tort claim will fail.
In this case, Dr. Dahlgren offered causation opinions based largely on epidemiological studies. (Epidemiology is the study of the incidence, distribution, and etiology of disease in human populations.) Epidemiology is usually considered highly probative evidence on general causation in toxic tort cases. The court may nonetheless exclude expert testimony based on epidemiological studies where the studies are insufficient, whether considered individually or collectively, to support the expert’s causation opinion. Nothing in either Daubert or the Federal Rules of Evidence requires a district court to admit opinion evidence that is connected to existing data only by the ipse dixit of the expert. A court may thus conclude that there is simply too great an analytical gap between the data and the opinion proffered.
A couple of parts of the court’s detailed analysis are worth highlighting for readers of MassTortDefense:
First, Dr. Dahlgren’s reliance on the “one-hit” or “no threshold” theory of causation in which exposure to one molecule of a cancer-causing agent has some finite possibility of causing a genetic mutation leading to cancer. The court noted that while the one-hit theory has been accepted for purposes of establishing regulatory safety standards, it has not been accepted as a reliable theory for causation under Daubert standards. See Allen v. Pennsylvania Eng’g Corp., 102 F.3d 194, 199 (5th Cir. 1996) (“Scientific 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.”); McClain v. Metabolife Int’l, Inc., 401 F.3d 1233, 1240 (11th Cir. 2005) (holding that district court erred by not excluding plaintiff’s expert’s causation opinion because he neglected dose-response relationship); Henricksen v. ConocoPhillips Co., 605 F. Supp.2d 1142, 1162 (E.D. Wash. 2009) (excluding expert’s opinion pursuant to Daubert where “he presumed that exposure to benzene in gasoline can cause AML in any dose.”); National Bank of Commerce v. Associated Milk Producers, Inc., 22 F. Supp.2d 942, 961 (E.D.Ark. 1998), aff’d, 191 F.3d 858 (8th Cir. 1999); Sutera v. Perrier Group of Am., Inc., 986 F. Supp. 655, 667 (D. Mass.
1997). Moreover, since benzene is ubiquitous, causation under the one-hit theory could not be established because it would be just as likely that ambient benzene was the cause of plaintiffs’ asserted illnesses.
Second, the court noted that to the extent that Dr. Dahlgren relied on the evidence that plaintiffs were exposed to benzene in excess of regulatory levels, that is insufficient to make his opinions admissible. The mere fact that plaintiffs were exposed to benzene emissions in excess of mandated limits is insufficient to establish causation. Nelson v. Tennessee Gas Pipeline Co., 243 F.3d 244, 252-53 (6th Cir. 2001); David L. Eaton, Scientific Judgment and Toxic Torts- A Primer in Toxicology for Judges and Lawyers, 12 J.L. & Pol’y 5, 39 (2003) (“regulatory levels are of substantial value to public health agencies charged with ensuring the protection of the public health, but are of limited value in judging whether a particular exposure was a substantial contributing factor to a particular individual’s disease or illness.”). This is because regulatory agencies are charged with protecting public health and thus reasonably employ a lower threshold of proof in promulgating their regulations than is used in tort cases. Allen, 102 F.3d at 198.
Third, the court focused on the issue of the link between cited literature and the actual specific opinion given. The court recognized that an expert’s opinion does not have to be unequivocally supported by all epidemiological studies in order to be admissible under Daubert. But here, the opinions expressed in Dr. Dahlgren’s revised report were based “on a scattershot of studies and articles which superficially touch on each of the illnesses at issue.” The expert had not differentiated the cases in any way and simply assumed that each reference supported his causation opinion on each and every illness. That clearly was not the case. Also, none of the cited studies supported an opinion that benzene can cause the illnesses from which plaintiffs suffer at the extremely low doses or exposures experienced in this case. Even if it is medically accepted that benzene can cause disease at high doses, Dr. Dahlgren could not cite any paper finding that the relevant low cumulative exposure significantly increases the risk of developing the injuries.
The court, therefore, found that the expert’s causation opinions were not reliable under the standards enunciated by Daubert and, consequently, inadmissible. Without Dr. Dahlgren’s testimony, the plaintiffs were unable to establish that their illnesses were caused by alleged emissions from the plant, the court observed, and so granted Chevron’s motion for summary judgment on all four bellwether personal injury plaintiffs.