In a toxic tort case, plaintiffs must establish general causation. If a substance is incapable of causing the type of injury plaintiff claims, then it certainly didn’t cause theirs. Under Texas law, toxic tort plaintiffs must prove general causation either by “direct, scientifically reliable proof,” or by “indirect” epidemiological evidence. Merrell Dow Pharms., Inc. v. Havner, 953 S.W.2d 706, 714-15 (Tex. 1977). In Newsome v. International Paper Company, plaintiff attempted to bypass this foundational requirement, and neither the district court, nor the Fifth Circuit was fooled. WL 5117195 (5th Cir. Dec. 16, 2024).
In Newsome, plaintiff was a truck driver for a company that supplied International Paper with sodium hydrosulfide (NaHS). Under certain conditions, NaHS releases hydrogen sulfide (H2S), an invisible gas with a characteristic rotten-egg odor. During a delivery in January 2019, plaintiff alleged he “smelt something” then “came to” on the ground. He presented to an urgent care clinic the following day but was diagnosed with only a rash. He did not visit a doctor again for four months. Then, more than a year later, plaintiff sued International Paper claiming “a host of life-threatening injuries” related to his alleged exposure to H2S.
International Paper moved for summary judgment based on plaintiff’s failure to establish general causation under Texas law. In response, nearly eight months after the deadline to disclose experts, plaintiff moved to replace his expert, Dr. Snyder, an occupational safety consultant, with a new general causation expert, Dr. Haimes, an occupational medicine physician. The magistrate judge denied the untimely designation and recommended the district court grant summary judgement, which it did. Plaintiff appealed both the denial of his motion to designate a new expert and the disposal of his case on summary judgement.
The Fifth Circuit affirmed the district court’s denial of plaintiff’s untimely motion to designate a new expert, finding that all four of the factors set forth in Geiserman v. McDonald dictated against granting such a motion. As to the grant of summary judgment, plaintiff first argued that Havner did not apply to his case at all in light of the immediate timing between the exposure and the loss of consciousness. The Fifth Circuit held that plaintiff’s argument could not rely solely on the concept of temporality. While it is true that temporal proximity “raises suspicion” of causation, “suspicion alone is insufficient” to establish it. Instead, under Havner, direct evidence is provided by controlled scientific experiments, none of which were performed, or cited, by plaintiff’s expert.
In fact, Texas case law dictates that establishing general causation solely by direct scientific evidence is only permitted to the extent that evidence already exists. Examples include mesothelioma related to asbestos exposure and lung cancer associated with smoking cigarettes. Also, in situations where multiple potential sources of the chemical exposure exist, Havner requires establishing causation via epidemiology anyway, to establish specific causation by comparison. See e.g., Bostic v. Georgia-Pacific Corp., 439 S.W.3d 332 (Texas 2014) (requiring epidemiological evidence of direct causation despite the concession that asbestos can cause mesothelioma).
Holding that Havner applied, the Fifth Circuit laid out the admissibility requirements for expert opinions based on indirect, epidemiological evidence. First, the court must “independently evaluate the foundational data” underlying the expert’s opinion. If those data are reliable, the court examines the design and execution of the epidemiological studies that evaluate it and must find at least two studies that meet reliability standards. Yet, that is not sufficient on its own. The overall epidemiological evidence must demonstrate that exposure to the substance at issue “more than doubles” the risk of injury.
Plaintiff argued that even if Havner did apply, his experts’ underlying data was sufficient. In support, he pointed to a laundry list of sources Dr. Snyder relied upon. Unconvinced, the Fifth Circuit asserted plaintiffs “cannot prove causation by presenting different types of unreliable evidence.” The panel held that Dr. Snyder’s occupational safety resources employ a lower threshold of proof than required by tort law. Further, Dr. Snyder himself acknowledged his data did not establish a causal relationship. Dr. Haimes’ proffered opinion rested on an equally weak foundation. He cited to an agency report, but the court found this was secondary literature and the underlying data Dr. Haimes highlighted from it was based on individual case reports and a single small study. The court again found this to be an insufficient foundation for an expert opinion.
As a final Hail Mary, plaintiff argued that defendant’s expert Dr. Kind had conceded general causation. But this, too, fell short of the Havner goal line. Dr. Kind summarized data from individual case reports and animal studies. The court held Dr. Kind’s opinion, like those of plaintiff’s experts, relied on insufficient data to establish general causation under Havner. In addition, Dr. Kind’s summary of the literature did not establish a dose dependent relationship between H2S and injury, undermining Dr. Snyder’s claims. The court concluded plaintiff could not cherry pick from Dr. Kind’s opinion, especially where the chosen parts remain insufficient.
In the end, the Fifth Circuit affirmed the district court’s conclusion — plaintiff’s experts’ accumulation of unreliable evidence could not distract from the insufficient foundation underlying their opinions. Occupational safety resources, agency reports, case reports and isolated, undersized studies are an insufficient foundation, even in aggregate. Given that most juries are unfamiliar with the science and subject matter in toxic tort cases, expert opinions are often their sole source of such evidence. The Fifth Circuit reinforced the court’s role in ensuring any opinion that makes it to the jury has a solid foundation, not just a distracting façade.
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