A recent case in New York reaffirms that under the now-minority Frye standard for the admissibility of expert opinion, testimony about the extent of a plaintiff’s exposure to an alleged toxic substance must rely on a sufficiently rigorous methodology.  See Sean R. v. BMW of North America LLC, 2016 WL 527107 (N.Y. Feb. 11, 2016).

Plaintiffs alleged their child was born with severe mental and physical disabilities as a result of in utero exposure to unleaded gasoline vapor; they brought a personal injury action against the manufacturer of the vehicle driven by the plaintiff mother during her pregnancy and an auto repair shop, alleging that the vehicle’s allegedly defective fuel hose and the repair shop’s failure to timely discover and fix the defective hose, combined to cause the child’s injuries.

The trial court granted the defendants’ motion to preclude plaintiffs’ causation experts from testifying at trial and the issue eventually reached the NY Court of Appeals.  The court affirmed, holding that the methodology employed by the experts was not generally accepted in the scientific community, and thus the experts’ testimony was inadmissible.

A central issue was exposure: even if a toxic substance can cause a type of injury under some circumstance, the fundamental notions of toxicology dictate that the effects of exposure relate to the dose of exposure.  Very often, there is no contemporaneous measure or testing that will indicate the level of exposure.  Instead, plaintiffs will typically seek to estimate a historical exposure level, by analogy to documented exposures similar product or work contexts, or reference to baseline data. Some plaintiffs will rely on a logical fallacy: if plaintiff testifies she has experienced an effect, then she must have experienced a dose sufficient to cause that alleged effect- the injury proves the cause. Indeed, here plaintiffs’ experts concluded that plaintiff’s mother inhaled 1,000 parts per million (ppm) of gasoline vapor based on the fact that she and others experienced symptoms of acute toxicity during exposure, such as headache, nausea and irritation of the throat and mucous membranes. For symptoms such as these to occur immediately, a gasoline vapor concentration of at least 1000 ppm is supposedly required.

The Court of Appeals noted that in toxic tort cases, an expert opinion on causation must set forth (1) a plaintiff’s exposure to a toxin, (2) that the toxin is capable of causing the particular injuries plaintiff suffered (general causation) and (3) that the plaintiff was exposed to sufficient levels of the toxin to cause such injuries (specific causation), see Parker v. Mobil Oil Corp., 7 N.Y.3d 434, 448, 824 N.Y.S.2d 584, 857 N.E.2d 1114 (2006). Although it is not always necessary for a plaintiff to quantify exposure levels precisely, the courts have never dispensed with a plaintiff’s burden to establish sufficient exposure to a substance to cause the claimed adverse health effect.  At a minimum, there must be evidence from which the fact-finder can conclude that the plaintiff was exposed to levels of the agent that are known to cause the kind of harm that the plaintiff claims to have suffered. See also Wright v. Willamette Indus., Inc., 91 F.3d 1105, 1107 (8th Cir.1996). In Frye jurisdictions, not only is it necessary for a causation expert to establish that the plaintiff was exposed to sufficient levels of a toxin to have caused his injuries, but the expert also must do so through methods found to be generally accepted as reliable in the scientific community.

The court agreed that plaintiffs here had failed to make that showing in this case. The experts concluded that the minor plaintiff was exposed to a sufficient amount of gasoline vapor to have caused his injuries based on the reports by plaintiff’s mother and grandmother that the smell of gasoline occasionally caused them nausea, dizziness, headaches and throat irritation. The experts did not identify any text, scholarly article or scientific study, however, that applied  this type of methodology, let alone a “consensus” as to its reliability.

The studies relied by plaintiffs merely supported a conclusion that there is a dose-response relationship between exposure to the chemical constituents of gasoline and symptoms of toxicity.  Certainly there were known exposure levels which cause people to report symptoms such as nausea and headache.  But while there is an ability to measure symptoms in response to a given exposure, those studies do not support the inverse approach employed in this case—working backwards from reported symptoms to divine an otherwise unknown concentration of gasoline vapor. The experts could not identify any study, report, article or opinion that admits or employs such a methodology.

Exclusion of expert opinion affirmed.