EPA Stands by CERCLA PFAS Designation Amid Legal Challenge

EPA under the Trump administration will defend a rule issued by the Biden administration designating two PFAS as hazardous substances under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), the agency told the D.C. Circuit Court of Appeals on September 17, 2025.

“EPA has completed its review and has decided to keep the Rule in place,” the agency wrote in a court filing.

The case, Chamber of Commerce of the USA v. EPA, No. 24-1193, consolidates challenges to the May 2024 rule.  It has been held in abeyance since February at EPA’s request while the Trump administration determined how to proceed.

EPA’s decision to defend the rule is somewhat unexpected.  Last month, the New York Times reported that internal EPA documents recommended its repeal, stating that its “cons outweigh pros.”

Key Impacts of the CERCLA Designation

The rule has significant consequences for EPA’s ability to respond to contamination and assign cleanup responsibility for PFOA and PFOS, the two PFAS covered by the designation.

“Designating PFOA and PFOS as CERCLA hazardous substances eliminates barriers to timely cleanup of contaminated sites, enables EPA to shift responsibility for cleaning up certain sites from the Fund to [potentially responsible parties (PRPs)], and allows EPA to compel PRPs to address additional contaminated sites,” the rule states.

Due to the designation, entities that release PFOA and PFOS above reportable quantities must notify authorities.  When releases occur, EPA (and other agencies) can more quickly respond, because they no longer need to first determine that the release “may present an imminent and substantial danger.”

Crucially, the designation also allows EPA to compel PRPs to take action in response to significant PFOS or PFOA contamination—often at their own expense.

The rule justifies listing PFOA and PFOS based on their health hazards, persistence and mobility in the environment, and bioaccumulation in humans and other organisms.  EPA also conducted a “totality of the circumstances” analysis, which weighed the pros and cons of their designation.

More on EPA’s PFAS and CERCLA actions can be found on our CERCLA archive.