EPA determined that almost all uses of methylene chloride (MC) pose an unreasonable risk of injury. EPA promulgated a rule under the Toxic Substances Control Act (TSCA) that nearly eliminates the market for MC.

On September 15, 2026, the US Court of Appeals for the Fifth Circuit vacated the MC Rule and its associated risk determination, due to “errors of law” and because “substantial evidence did not support EPA’s decision.”

Less Deferential Judicial Review under TSCA
Judicial review under TSCA is less deferential than review of most agency rules. TSCA requires that the agency’s decision be based upon the entire record, including evidence that detracts from the agency’s decision. It also requires the agency’s decision to be based on what a reasonable mind would accept as adequate support. Due to these TSCA requirements, courts have inferred a congressional intent that reviews of TSCA rules should be more rigorous and more searching than the typical review based on the “arbitrary and capricious” standard.

TSCA Requires Evaluation of Conditions of Use
EPA promulgated the MC Rule after determining MC posed an unreasonable risk “as a whole chemical substance.” The 5th Circuit agreed with the industry petitioners that TSCA focuses on determining and regulating risk according to the actual, separate “conditions of use” for a given substance. The agency lacked legal authority to analyze MC’s risk “as a whole” rather than to evaluate each of its conditions of use.

Flawed Scientific Analysis
The 5th Circuit also criticized multiple components of EPA’s scientific analysis. EPA discounted relevant human studies; it assumed (contrary to law) no PPE use by workers, despite OSHA requirements; and it relied on a rat study with extreme exposures, questionable results, and gross extrapolation. As a result, EPA’s actions were arbitrary and capricious and failed to meet the more demanding TSCA standards.

To see the opinion https://www.ca5.uscourts.gov/opinions/pub/24/24-60256-CV0.pdf