As previously reported, the U.S. Chamber of Commerce and two other trade groups have challenged EPA’s designation of PFOA and PFOS as hazardous substances under CERCLA.  On November 14, 2025, petitioners filed their Joint Reply Brief in the U.S. Court of Appeals for the D.C. Circuit, again urging the court to vacate EPA’s Final Rule.  

Petitioners reiterate three core arguments: (1) EPA applied an overly expansive interpretation of the statutory phrase “may present substantial danger”; (2) EPA introduced a new cost analysis for the first time in the Final Rule, depriving stakeholders of meaningful comment; and (3) EPA proceeded despite significant scientific and regulatory uncertainties, rendering the Final Rule arbitrary and capricious. 

Petitioners maintain that EPA’s reading of CERCLA § 102(a) lacks a limiting principle by treating “may” as satisfied by any potential association with adverse effects. They contend this interpretation eliminates the distinction between CERCLA’s “hazardous substance” and “pollutant or contaminant” standards.

Petitioners also argue that EPA violated the Administrative Procedure Act by adding a roughly 300-page Regulatory Impact Analysis and new cost rationale in the Final Rule after proposing a cost-blind approach. Petitioners additionally point to operational and compliance costs, such as enhanced treatment at landfills and wastewater facilities, materials testing, and changes in handling and disposal practices, arguing EPA credited the benefits of these behaviors while excluding their associated costs.

Petitioners highlight EPA’s September 2025 announcement that it will develop a “Framework Rule” to establish uniform criteria for future § 102 designations. They argue this reflects EPA’s recognition that additional guardrails and cost considerations are needed and that this supports vacatur rather than remand.

By way of background, EPA has defended the Final Rule as a lawful, precautionary use of CERCLA § 102(a).  EPA argues that the robust evidence of toxicity, persistence, and mobility supports its factor‑based “substantial danger” finding, and that the designation strengthens cost recovery and enforcement against responsible parties.  EPA also maintains that it reasonably considered costs and uncertainties, satisfied APA notice‑and‑comment requirements, and that any defect would warrant remand without vacatur given the public‑health stakes.  The new administration has not altered this position.  In its September 17, 2025 filing, EPA moved to lift the Court’s abeyance and confirmed that it would keep the Final Rule in place.    

Final briefs are due December 5, 2025, with oral argument scheduled for January 20, 2025. The case is Chamber of Com. v. EPA, D.C. Cir., No. 24-01193