The Fifth Circuit recently affirmed the dismissal of most of a plaintiff’s personal injury claims against a chemical company, based on the conclusion that certain expert witness testimony was inadmissible. See Johnson v. Arkema Inc., No.11-50193 (5th Cir. June, 2012).
Plaintiff Johnson worked as a machine repairman at a glass bottling plant in Waco, Texas from May 1998 to the end of 2008. On two separate occasions, first in early June 2007 and again in July 2007, Johnson claims he was directed to perform work in close proximity to a device known as a C-4 Hood, which was designed, manufactured, and installed by defendant. C-4 Hoods are
utilized to apply a chemical coating to the glass bottles as the bottles are transported along a conveyor belt. According to Johnson, the C-4 Hood he worked near to on those two occasions failed to perform its proper functions, resulting in his alleged exposure to harmful chemicals.
Plaintiff sued. Arkema then filed motions to exclude the opinions of Dr. Richard Schlesinger, Johnson’s expert toxicologist, and Dr. Charles Grodzin, Johnson’s expert pulmonologist, under Federal Rule of Evidence 702 and the Supreme Court’s decision in Daubert v. Merrell Dow Pharm., Inc., 509 U.S. 579 (1993). Arkema also filed a motion for summary judgment, contending that absent those experts, Johnson was unable to present scientifically reliable evidence establishing that exposure to the chemicals can cause restrictive lung disease and pulmonary
fibrosis (his alleged injury types). The district court granted the motions, and plaintiff appealed.
On appeal, plaintiff contended that the district court abused its discretion in excluding Dr. Schlesinger’s expert opinion on general causation. The district court excluded Dr. Schlesinger’s testimony after determining, inter alia, that: (1) Dr. Schlesinger could not cite to one epidemiological or controlled study of humans indicating that exposure to the relevant chemicals could cause restrictive lung disease and pulmonary fibrosis; (2) the scientific literature was devoid of any data or peer reviewed articles indicating that exposure to the two chemicals will result in chronic lung disease, and such a proposition is not generally accepted in the scientific community.
Plaintiff argued that the two fell into a “class” of chemicals that have been shown to cause these injuries. In forming a reliable opinion regarding the effects of exposure to a particular chemical, an expert may extrapolate data from studies of similar chemicals. BUT to support a conclusion based on such reasoning, the extrapolation or leap from one chemical to another must be reasonable and scientifically valid. Thus, courts are free to reject a theory based on extrapolation when there is simply too great an analytical gap between the data and the opinion proffered. Here, save for highlighting their shared classifications as “irritants,” the expert did not attempt to explain any direct correlation or “fit” between the chemicals at issue and the known scientific data concerning exposure to, for example, chlorine, ammonia, or nitric acid vapor. Accordingly, given the diverse chemical structures and toxicities of irritants, which plaintiff acknowledged, the district court did not abuse its discretion in concluding that Dr. Schlesinger’s “class of chemicals” theory presented “too great an analytical gap between the data and the opinion proffered.
The next issue was reliance on language in an MSDS, which is useful for many of our readers in toxic tort cases. The district court found the “warning” language in a competitor’s MSDS to be irrelevant and unreliable because: it did not clearly state a causation conclusion, and, most importantly, Johnson did not provide any science behind the MSDS, such as the duration or concentration of exposure needed to produce the noted effects, or the scientific literature relied upon by the drafter for the statements contained in the MSDS. Under such circumstances, the MSDS, standing alone, need not have been accorded any weight. Plaintiff also relied on general hazard language in defendant’s own MSDS. But could cite no authority for the proposition that material safety data sheets constitute per se reliable support for an expert’s opinion. To the contrary, in exercising its discretion as a gatekeeper, a court may refrain from treating a MSDS as reliable until it is presented with scientific evidence justifying the relevant statements found within the MSDS.
Finally, Johnson contended that he was exposed to amounts of one of the chemicals (HCl) that were between two and ten times the permissible exposure levels set by OSHA, NIOSH, and the Acute Exposure Guideline Levels set by the National Research Council. Regulatory and advisory bodies such as IARC, OSHA and EPA utilize a “weight of the evidence” method to assess the carcinogenicity or toxicity of various substances in human beings and suggest or make prophylactic rules governing human exposure. This methodology results from the preventive perspective that the agencies adopt in order to reduce potential public exposure to possibly harmful substances. The agencies’ threshold of proof is lower (for policy reasons) than that appropriate in tort law, which traditionally makes more particularized inquiries into cause and effect, and requires a plaintiff to prove that it is more likely than not that another individual has caused him or her harm. See generally Wright v. Willamette Industries, Inc., 91 F.3d 1105, 1107 (8th Cir.1996). Thus, such regulatory chemical guidelines are not necessarily reliable in all toxic tort cases. And a court should confirm the underlying basis for their proscriptions before an expert’s reliance on them can pass Daubert muster. Here, plaintiff did not provide any scientific data or literature to explain how or why the various exposure limits and guidelines were established for the chemicals. Similarly, he had no evidence that the guidelines and exposure limits existed to protect people from developing severe restrictive lung disease and pulmonary fibrosis, his diseases. Thus, the court concluded that the OSHA, NIOSH, and NRC guidelines and exposure limits, standing alone, were insufficient to demonstrate abuse of discretion on the part of the district court.
As to the other expert, Dr. Grodzin’s research and analysis essentially mirrored Dr. Schlesinger’s save for one key distinction: Dr. Grodzin performed a so-called “differential diagnosis” of Johnson. A reliable differential diagnosis typically, though not invariably, is performed after physical examinations, the taking of medical histories, and the review of clinical tests, including laboratory tests, and generally is accomplished by determining the possible causes for the patient’s symptoms and then eliminating each of these potential causes until reaching one that cannot be ruled out. Even in jurisdictions that accept this questionable approach to causation, the results of a differential diagnosis are far from reliable per se. For example, before courts can admit an expert’s differential diagnosis, which, by its nature, only addresses the issue of specific causation, the expert must first demonstrate that the chemical at issue is actually capable of harming individuals in the general population, thereby satisfying the general causation standard. In other words, the suspect has to be reasonably and reliably “ruled in.”
Here, Dr. Grodzin’s differential diagnosis was based on the presumption that the two chemicals were actually capable of causing restrictive lung disease and pulmonary fibrosis in the general population. Dr. Grodzin did not present any reliable or relevant scientific evidence to bolster this assumption. Consequently, the fact that Dr. Grodzin claimed he conducted a differential
diagnosis did not save his opinion from the same fate as Dr. Schlesinger’s opinion.
(Note, the court concluded that plaintiff did not need expert witnesses to demonstrate that his immediate acute injuries after exposure and which allegedly sent him to the emergency room, could have been caused by the chemical. Thus, this part of the case was remanded.)