Opinion ID: 513179
Heading Depth: 2
Heading Rank: 3

Heading: Recurrent Versus Rare Exposure

Text: 53 The third statutory issue is whether section 4 of TSCA authorizes EPA to issue a test rule where any individual's exposure to a chemical is likely to be a rare, brief event. CMA contends that only recurrent exposure warrants a test rule. EPA maintains that it can issue a test rule in the absence of recurrent exposure, where there is a more-than-theoretical basis for suspecting that infrequent or single-dose exposure presents an unreasonable risk of injury to health. We find no indication in the statute or its history that Congress addressed this particular issue, but once again turning to the second prong of Chevron, we deem reasonable the Agency's construction of section 4 as permitting a test rule even where exposure is not recurrent.
54 Requiring testing in the absence of recurrent or long-term exposure would be unreasonable only if there were not a more-than-theoretical probability that non-recurrent, brief exposure could create an unreasonable risk of injury to health. Here the agency has already concluded that even one-time exposure to suspected developmental toxicants (of which EHA is one) may be sufficient to cause harm to a developing fetus. Guidelines for the Health Assessment of Suspect Developmental Toxicants, 51 Fed.Reg. 34,028, 34,037 (1986). Where the pool of potentially exposed persons consists of hundreds of individuals, and where the substance in question is toxic in small doses, the mere fact that exposure events might occur on an accidental, rare or occasional basis would not prevent the substance from potentially causing a significant degree of injury to human health. To interpret TSCA as not authorizing testing where potential exposure is brief or non-recurrent would render it ineffective in such circumstances. Certainly, this court should not substitute its judgment for that of the Agency on the issue of whether occasional exposure to a developmental toxicant can ever merit a test rule. We therefore hold the EPA construction of section 4 on this point to be reasonable and consistent with the purpose of TSCA. 16
55 We are not dissuaded from this conclusion by the cases in two other circuits CMA cites to bolster its claim that recurrent exposure is necessary to justify testing under section 4 of TSCA. See Ausimont U.S.A., Inc. v. EPA, 838 F.2d 93 (3d Cir.1988); Shell Chemical Co. v. EPA, 826 F.2d 295 (5th Cir.1987). It is true that both Ausimont and Shell mention amount of exposure as a relevant factor in a determination of unreasonable risk Ausimont, 838 F.2d at 96; Shell, 826 F.2d at 298. Neither of the opinions, however, asserts that a particular quantity of exposure is needed in all instances to warrant a test rule. Nor do they assert that individuals must be exposed repeatedly. The cases lay down no statutory interpretation inconsistent with the one EPA has adopted. Assuredly, amount or quantity of exposure is relevant in determining whether there is a more-than-theoretical basis for suspecting that the combination of toxicity and exposure is sufficient to present an unreasonable risk of injury to health. Clearly, the necessary amount of exposure to meet that norm will vary depending on the level of exposure at which the substance's toxicity is likely to present an unreasonable risk of injury to health. None of this is to say, however, that EPA can never issue a test rule unless recurrent exposure takes place.