D.C. Circuit Court of Appeals Denies Petitions Challenging the Designation of PFOA and PFOS as Hazardous Substances Under CERCLA

On August 18, 2026, the D.C. Circuit Court of Appeals denied petitions challenging EPA’s April 2024 designation of perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) as hazardous substances under CERCLA.

In rejecting petitions for review filed by seven interest groups representing industries that use, transport, or discharge PFOA and PFOS, the court made three key findings:

• “The plain language of Section 9602 allows EPA to designate as hazardous substances chemicals like PFOA and PFOS that repeatedly have been linked to adverse health effects in myriad peer-reviewed studies.”

• “EPA provided adequate notice of its cost-benefit analysis underlying the ultimate Designation through its earlier Economic Assessment and request for comments on it.”

• “EPA acted reasonably based on the record before it in its calculation of costs and benefits, and in its decision to take this regulatory step of designating PFOA and PFOS to be hazardous substances.”

Among other things, this ruling emphasizes the importance for companies to include consideration of PFOA and PFOS when conducting environmental due diligence to meet CERCLA’s “all appropriate inquiries” standard for liability protection, which is typically performed via Environmental Site Assessments. For additional information, please see Farella's prior post, dated May 8, 2024.

The court’s decision can be found here. Our previous posts discussing the designation of these PFAS under CERCLA include Farella's initial post on April 19, 2024, and previous posts discussing this legal challenge include Farella's initial post on July 29, 2024.