On September 15, 2026, the U.S. Court of Appeals for the Fifth Circuit vacated and remanded EPA’s methylene chloride (“MC”) risk management rule and associated risk determination under the Toxic Substances Control Act (“TSCA”) in East Fork Enterprises, et al. v. EPA. The court held that EPA’s rules did not meet the substantial evidence standard under TSCA, were founded on arbitrary and capricious assumptions, and were based on a “whole chemical” methodology that EPA lacked authority to use. The court’s decision opens the door for further challenges to EPA’s TSCA risk management rules that employed similar risk evaluation methodologies.
Background
In June 2020, EPA promulgated a final risk evaluation that addressed 53 conditions of use for MC and evaluated the actual risk to human health and the environment under each condition of use. EPA’s final risk determination concluded that MC (1) does not pose an unreasonable risk to the environment; (2) poses an unreasonable risk to health for 47 conditions of use; but (3) does not pose an unreasonable risk to health for the six other conditions of use. In November 2022, EPA revised its risk determination to make two significant changes. First, rather than relying on separate risk determinations for each condition of use, EPA issued a “whole chemical” determination that all but one of the 53 conditions of use posed an unreasonable risk to human health. Second, EPA assumed that employees were not wearing personal protective equipment (“PPE”) when exposed to MC under each condition of use, whereas EPA had assumed PPE use in accordance with OSHA requirements in the June 2020 rule. In May 2024, EPA promulgated its final risk management rule for MC under TSCA, prohibiting 40 of the 53 conditions of use and allowing 13 commercial or industrial conditions of use, subject to a Workplace Chemical Protection Program and/or MC exposure limits.
The Fifth Circuit’s Decision
The Fifth Circuit found that TSCA requires EPA to issue a risk determination for each condition of use, which EPA has traditionally done in other TSCA risk determination rulemakings. The court held that EPA improperly abandoned a use-by-use determination in its November 2022 MC risk determination and lacked authority to issue a “whole chemical” risk determination under TSCA. The court also found that EPA’s assumption on the non-use of PPE was contrary to law, arbitrary and capricious, and lacked substantial evidence.
EPA argued that the court should defer to the agency’s factual findings regarding what constitutes an unreasonable risk based on the agency’s technical expertise using the methodology set forth in TSCA. The court rejected EPA’s position and found that “unreasonable risk” is not a factual finding made by the agency, but rather a legal determination construed by the court in a post-Loper Bright world. In reviewing EPA’s conclusions, the court found that EPA’s approach to “unreasonable risk” was overly conservative and resulted in the agency finding exaggerated unreasonable risk for the conditions of use. The court held that EPA’s conclusions on unreasonable risk did not accord with best available science as required under TSCA and were arbitrary and capricious, lacking substantial evidence, and contrary to law. The court also found that EPA failed to properly consider alternatives to a near-total ban on MC applications and the economic consequences of its regulation.
The Impact of the Decision
The Fifth Circuit’s decision is likely to have ripple effects through pending litigation challenging other TSCA risk management rules throughout the country. For example, the East Fork decision has already been cited in cases pending before the Third Circuit challenging EPA’s risk management rule for trichloroethylene (“TCE”). Additionally, the decision will impact the agency’s ongoing risk management rulemakings for other chemicals, some of which rely on methods similar to those employed in the MC rules. Stakeholders should follow the pending litigation and rulemakings and watch our blog for further updates.