D.C. Circuit Upholds PFOA/PFOS Hazardous-Substance Designations

By Patrick Paul, John Habib, and Sukhmani Singh

On August 18, 2026, the D.C. Circuit denied industry petitions to vacate EPA’s 2024 designation of PFOA and PFOS as “hazardous substances” under CERCLA. Chamber of Commerce of the United States v. EPA, No. 24-1193 (D.C. Cir. Aug. 18, 2026). The decision left EPA’s designations intact, and with them, the full suite of CERCLA reporting, disclosure, and liability consequences that Arizona businesses need to plan around, even as EPA simultaneously moves to roll back PFAS drinking-water standards on a separate regulatory track.

EPA’s Designation

In May 2024, EPA finalized a rule designating PFOA and PFOS — two of the most common “forever chemicals” — as “hazardous substances” under CERCLA. EPA based the designation on two factors: (1) the potential harm to humans or the environment from exposure, and (2) how the substances move, persist, and change in the environment. In making the designation, EPA credited numerous studies linking PFOA and PFOS to cancer, developmental effects in children, cardiovascular conditions, immunosuppression, and impaired thyroid and liver function. EPA also found that PFOA and PFOS take centuries to degrade into the environment and decades to be eliminated from human bodies — which earned them the “forever chemicals” label.

The designation elevated PFOA and PFOS from their prior status as mere “pollutants or contaminants” (which EPA can address only on a site-by-site, imminent-danger basis with taxpayer funds) to “hazardous substances” (which trigger reporting obligations, federal land-sale disclosures, and, critically, the ability to compel responsible parties to pay for cleanups).

The Challenge

Seven industry groups — led by the U.S. Chamber of Commerce, the American Chemistry Council, and the American Fuel & Petrochemical Manufacturers — argued that EPA (1) misread CERCLA’s “may present substantial danger” standard, (2) failed to provide adequate notice of its final cost-benefit analysis, and (3) acted arbitrarily in regulating despite acknowledged uncertainties about future cleanup costs and liability exposure. These industry groups asked the court to eliminate EPA’s designation.

The Court’s Reasoning

The court rejected all three claims. On statutory interpretation, it held that “may present substantial danger” carries its ordinary meaning — a scientifically supported possibility of substantial harm, not a certainty that harm “will” occur upon every release. The court reasoned that CERCLA’s “substantial danger” threshold provides an intelligible principle tied to scientific evidence. The court concluded that EPA’s 2022 Economic Assessment and its explicit request for cost-related comments gave petitioners adequate opportunity to weigh in before EPA finalized the more detailed Regulatory Impact Analysis in 2024. Finally, the court credited EPA’s explanations for its cost estimates — including marginal-cost assumptions at sites already cleaning up other hazardous substances — and noted that CERCLA’s multistep enforcement process and statutorily-available defenses limited the industry groups’ liability exposure.

What Stays in Place

EPA’s PFOA and PFOS designations carry three direct obligations: (1) reporting releases of more than one pound of PFOA or PFOS to federal authorities; (2) notice of contamination when federal agencies sell land; and (3) hazardous-materials marking for shipments exceeding one pound. Indirectly, EPA can now compel responsible parties to clean up PFOA and PFOS contamination under Section 106 and pursue cost-recovery actions under Section 107 — shifting expenses from taxpayers to polluters.

Takeaways

For industrial dischargers, waste handlers, and real estate stakeholders, the upshot is that CERCLA liability for PFOA and PFOS is not going away. Facilities that generate, transport, or dispose of materials containing PFOA or PFOS should confirm their release-reporting protocols and evaluate whether legacy contamination at current or former sites may trigger enforcement. Real estate transactions involving properties with known or suspected PFAS contamination should continue to account for CERCLA disclosure obligations and potential successor liability.