On August 18, 2026, the D.C. Circuit unanimously upheld the Environmental Protection Agency’s (EPA) designation of perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) as “hazardous substances” under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) in Chamber of Commerce of the United States v. EPA. The decision confirms the EPA’s authority to regulate emerging contaminants under CERCLA.
The decision significantly expands liability exposure for companies and reinforces the chemicals’ status as hazardous substances, triggering reporting requirements, federal land sale disclosure obligations, and enabling EPA and private-party enforcement actions.
The D.C. Circuit’s Decision
A coalition of industry groups, including the Chamber of Commerce, petitioned for review. In a unanimous opinion by Judge Millett, joined by Judges Katsas and Rao, the court denied all petitions.
Interpreting “May Present Substantial Danger”
The petitioners argued that “may” in CERCLA’s designation standard should mean “will,” requiring the EPA to prove certain harm before designation. They also raised nondelegation and void-for-vagueness challenges.
The court rejected these arguments, holding that “may” carries its ordinary meaning of possibility, not certainty. The EPA therefore may designate a substance based on a scientifically plausible substantial risk without proving that harm is certain to occur. Requiring demonstrated harm would “legislatively paralyze CERCLA.” The word “substantial” provides meaningful constraint—that risk must be “serious and real, not hypothesized.”
The court also rejected claims that hazardous substances must pose greater risk than pollutants or contaminants, finding that CERCLA creates two distinct cleanup regimes—a “belt and suspenders approach.”
The constitutional challenges also failed. The court held that Section 102(a)’s public-health standard provides an “intelligible principle” and that the petitioners had fair notice that PFOA and PFOS might be designated.
Notice and Comment Challenge
The petitioners claimed that the EPA violated the Administrative Procedure Act (APA) by withholding its regulatory impact analysis until the final rule, arguing it differed materially from the earlier economic assessment.
The court disagreed. The proposed rule requested comment on costs, and several petitioners urged the EPA to conduct a formal RIA. The EPA obliged. Petitioners, the court said, “cannot be prejudiced by getting what they asked for.”
Reviewing EPA’s Cost-Benefit Analysis
The court rejected six specific challenges to the EPA’s cost-benefit analysis:
- National Priorities List (NPL) site cleanup costs. The EPA reasonably assumed only marginal increases in PFOA and PFOS cleanup costs because infrastructure was already in place at NPL sites.
- Non-NPL site costs. The EPA reasonably estimated 133 enforcement sites—not the 57,412 claimed by the petitioners, which covered all per- and polyfluoroalkyl substances (PFAS), not just PFOA and PFOS.
- Costs at federal facilities. The EPA reasonably explained its analysis of cleanup costs at federal facilities. In any event, any miscalculation would not affect the petitioners because these costs concern the government’s own expenditure on its own sites.
- Industry-specific costs. The EPA properly analyzed costs to the waste management and construction industries. The court found that an agency need not conduct a “deep-dive, individualized cost-benefit analysis” for every affected industry.
- Benefits calculation. The EPA permissibly characterized transferring costs from taxpayers to alleged polluters as an “advantage” that would free Superfund resources for other sites.
- Regulatory Flexibility Act. The EPA need not consider indirect effects on small businesses when those effects depend on “multiple intervening and uncertain events.”
The court emphasized the extensive procedural steps before CERCLA liability attaches, including NPL listing (requiring notice and comment), site evaluation, remedial-action planning with cost-effectiveness analysis, and another comment period before liability questions arise.
Multiple statutory defenses also apply, including acts of God, third-party defenses, de minimis contributions, and innocent landowner protections. As the court observed, PFOA and PFOS are “two drops in a bucket” of over 800 hazardous substances, and the existing system has not been unfairly applied.
What the Decision Means
By leaving the PFOA and PFOS designations in place, the decision carries significant liability, reporting, and compliance implications for businesses that have used, stored, or released the substances.
PFOA and PFOS remain CERCLA hazardous substances. The unanimous panel opinion provides strong precedent that will be difficult to disturb.
Expanded liability. Companies with current or historical ties to PFOA or PFOS now face cost-recovery and enforcement actions. The EPA can compel cleanup under Section 106, and private parties—including municipalities, water utilities, and downstream owners—may pursue cost recovery under Section 107.
Reporting obligations. Releases exceeding one pound of PFOA or PFOS trigger federal reporting requirements. Facilities using or storing these substances should evaluate whether ongoing or historical releases require notification.
Statutory defenses remain. The court emphasized the extensive procedural protections and defenses between designation and actual liability. Companies should assess the applicability of CERCLA’s de minimis, innocent landowner, and third-party defenses.
Affected industries. Manufacturing, waste management, construction, chemical production, firefighting foam users, wastewater treatment, and commercial real estate should assess historical and current PFOA or PFOS use.
Future PFAS designations. The court’s broad reading of the EPA’s authority may support additional PFAS designations in future rulemakings. The opinion endorses the EPA’s predictive, probability-based approach to risk assessment.
Compliance Considerations
Companies should:
- Inventory historical and current PFOA/PFOS use.
- Evaluate whether releases trigger reporting.
- Assess exposure to contribution claims.
- Review insurance coverage.
- Monitor EPA enforcement priorities.
If you have any questions, or would like additional information, please contact one of the attorneys on our Environmental, Land Use & Natural Resources team.
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