Appeals Court Vacates EPA's Methylene Chloride Rule

The United States Court of Appeals for the Fifth Circuit has determined that EPA’s May 2024 final rule banning most uses of the solvent methylene chloride exceeds the agency’s authority under the Toxic Substances Control Act. The court’s decision in East Fork Enterprises Inc. v. EPA, which was filed Sept. 15, found fault with many elements of the agency’s final rule and the 2022 risk evaluation on which it was based.

In its risk evaluation, EPA determined that methylene chloride presents “unreasonable risk” to workers in 53 conditions of use, or COUs. The rule prohibited 40 COUs and required risk management measures for the 13 remaining COUs. These measures included requirements of a Workplace Chemical Protection Program that established a short-term exposure limit for methylene chloride of 16 ppm as a 15-minute time-weighted average (TWA) and an existing chemical exposure limit (ECEL) of 2 ppm as an eight-hour TWA. The court ruled that EPA’s analysis establishing these exposure limits relied on an inadequate study of exposures to rats and did not take into account other studies that did not support the agency’s conservative STEL and ECEL. For comparison, the court noted that OSHA’s STEL and permissible exposure limit for methylene chloride have remained 125 ppm (15-minute TWA) and 25 ppm (eight-hour TWA) since 1997. The results of EPA’s risk evaluation “more closely approximate the precautionary principle than [TSCA’s] ‘unreasonable risk’ standard,” the decision states.

For its 2022 methylene chloride risk evaluation, EPA adopted a “whole chemical” approach, according to which the agency made a single finding of unreasonable risk for the substance. The court ruled that TSCA requires separate risk determinations for each COU.

The risk evaluation also assumed that workers exposed to methylene chloride would not be wearing personal protective equipment. “According to the TSCA, EPA must account for PPE in its risk evaluations as a ‘condition of use’ if evidence reflects that PPE is actually used,” the court ruled.

For more information, refer to the court’s decision, EPA’s 2024 final rule in the Federal Register, and the agency’s risk management page for methylene chloride.

Related: Read “Complying With EPA’s Methylene Chloride Rule” in the April 2025 issue of The Synergist.