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On August 18, 2026, a unanimous panel of the U.S. Court of Appeals for the D.C. Circuit upheld the 2024 designation by the U.S. Environmental Protection Agency (EPA) of perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) as hazardous substances under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA or Superfund). (See Chamber of Commerce of the United States of America, et al. v. EPA, No. 24-1193 (D.C. Cir. Aug. 18, 2026).)
The decision leaves EPA’s PFOA and PFOS hazardous substance designations in place and provides guidance on the scope of EPA’s authority to make future hazardous substances designations under CERCLA Section 102(a). The decision also likely resolves a challenge to the rule that has spanned two presidential administrations. After taking office, the Trump administration had obtained an abeyance of the litigation challenging the Biden-era rule while EPA reconsidered its position. In September 2025, EPA informed the court that it had decided to retain the designations, while signaling that it would work with Congress and industry to address CERCLA liability concerns for “passive receivers.” The litigation then resumed, with the current Administration defending the rule.
“May Present Substantial Danger” Does Not Require Certainty
The 2024 rule marked EPA’s first use of its standalone authority under CERCLA Section 102(a) to designate additional hazardous substances. That provision authorizes EPA to designate additional substances that, “when released into the environment may present substantial danger to the public health or welfare or the environment.” The industry petitioners argued that EPA was required to show that substantial danger would occur following a release and that EPA’s possibility-based interpretation otherwise left the statutory standard without adequately fixed boundaries.
The court disagreed. Writing for the panel, Judge Patricia Millett explained that “may present substantial danger” expresses possibility rather than certainty. Requiring EPA to establish what will happen after every individual release, the court reasoned, would be inconsistent with both the statutory text and CERCLA’s reliance on evolving scientific evidence.
However, the court also emphasized that EPA’s authority is not unlimited. The phrase “substantial danger” requires a risk that is serious and real, rather than merely hypothetical. The panel did not define the outer limits of that standard because petitioners did not dispute that PFOA and PFOS could satisfy it. EPA’s rule relied on an extensive scientific record linking human exposure to the two substances with various health effects and carcinogenicity concerns. The Court’s ruling paves a legal pathway for additional hazardous substance designations under CERCLA Section 102 where EPA’s record supports a determination that risk is serious and real, albeit short of certain.
The opinion is notable because, applying Loper Bright Enterprises v. Raimondo, the court independently interpreted Section 102(a) rather than deferring to EPA’s construction of the statute but nevertheless concluded that the agency had the best reading of Section 102(a).
Cost-Benefit and Uncertainty Challenges Also Fail
The petitioners separately argued that EPA’s final Regulatory Impact Analysis differed too substantially from the Economic Assessment released with the proposed rule that it amounted to a violation of the Administrative Procedure Act’s public notice requirements. The court, however, held that the final analysis was a logical outgrowth of the proposal and the comments EPA received. In particular, EPA had expressly requested input on whether and how to consider costs, and petitioners themselves had urged the agency to conduct a more detailed quantitative analysis.
The panel also rejected challenges to EPA’s cleanup cost estimates at both National Priorities List (NPL) and non-NPL sites and federal facilities, as well as its analyses of industry-specific impacts, benefits and effects on small businesses. Applying deferential arbitrary and capricious review, the court concluded that EPA had considered the relevant issues and reasonably explained its assumptions.
However, a key question remains open: The court did not decide whether CERCLA Section 102(a) requires EPA to consider costs when designating a hazardous substance. EPA assumed that it did, and the court adopted the same assumption for purposes of the case.
The court likewise rejected the argument that EPA could not act amid uncertainty about where cleanup actions may occur or what they may cost. Designation is an initial regulatory step; it does not itself select a site for cleanup, identify a responsible party or allocate response costs. Those determinations remain subject to additional site-specific processes and statutory requirements.
Further Review Remains Possible
Absent a timely petition for rehearing or an extension, the deadline to seek Supreme Court review falls in November 2026. A timely petition for rehearing would reset the period for seeking certiorari to run from the disposition of that petition. Whether rehearing would be granted or the Supreme Court would grant review are both uncertain. A petition for certiorari would not by itself suspend the rule; absent a stay, regulated parties should continue to treat the designations and their associated obligations as operative.
EPA’s Enforcement Policy Focuses on Significant Contributors
In connection with the final rule, EPA issued its April 19, 2024, PFAS Enforcement Discretion and Settlement Policy Under CERCLA, which describes how the agency intends to prioritize CERCLA enforcement involving PFOA and PFOS. EPA states that it will focus on entities that significantly contributed to releases, including manufacturers, entities that used PFAS in manufacturing, and other industrial parties, as well as federal agencies and facilities.
Where equitable factors do not support enforcement, EPA generally does not intend to seek response actions or costs from community water systems and publicly owned treatment works, municipal separate storm sewer systems, publicly owned or operated municipal solid waste landfills, publicly owned airports and local fire departments, and farms that apply biosolids. EPA may extend enforcement discretion to other parties based on factors such as their public-service role and degree of involvement in the use, storage, treatment, transport, or disposal of PFAS.
Those protections are conditional. Any party seeking the benefit of enforcement discretion must cooperate fully with EPA, including by providing requested access and information and not interfering with response activities, and must continue to comply with CERCLA’s release-reporting requirements. EPA also reserves the right to pursue an otherwise covered entity whose actions or inactions significantly contribute to or exacerbate the spread of significant PFAS contamination. Outside the protection afforded by a settlement, the policy does not prevent private parties from pursuing CERCLA cost-recovery or contribution claims.
Although the policy provides useful insight into EPA’s current enforcement priorities, it is nonbinding, creates no enforceable rights, does not modify CERCLA’s statutory liability framework, and may be revised, withdrawn, or replaced.
Practical Implications
Absent appeal and injunction, the designations impose immediate obligations, including reporting releases above applicable thresholds, providing notice in certain federal property transfers, and identifying and marking qualifying shipments. Their more consequential effects, however, are likely to emerge through site-specific CERCLA proceedings. At active and legacy sites, the addition of PFOA and PFOS could expand ongoing investigations, affect remedy decisions, or prompt consideration of PFOA and PFOS in connection with existing remedies and site conditions.
At sites governed by existing CERCLA consent decrees, parties should also examine reopener provisions to assess whether the upheld designation, together with known or newly identified PFOA or PFOS conditions, may affect the continued appropriateness of the existing remedy or warrant additional response actions.
The designations also establish the hazardous substance predicate for natural resource damages (NRD) claims under CERCLA based on releases or threatened releases of PFOA or PFOS. While natural resource trustees still must establish a natural resource injury, causation, timing and other statutory requirements, PRPs at sites where PFOA or PFOS are present should be aware that NRD may now become an additional consideration and exposure to be managed.
The potential magnitude of PFAS-related NRD exposure is already evident in recent settlements under state NRD law. Most recently, on August 7, 2026, a federal court approved New Jersey’s combined settlements with DuPont entities and 3M valued at approximately $2.5 billion, including up to $365 million for NRD and restoration. Earlier resolutions include New Jersey’s 2024 Solvay and Arkema settlements, which together allocated approximately $88 million to NRD, Ohio’s 2023 settlement with Dupont for $110 million, and Minnesota’s 2018 $850 million settlement with 3M. Although these settlements arose principally under state-law authorities, their scale illustrates the potential stakes of PFAS-related trustee claims.
The decision also gives EPA a clearer legal pathway for considering additional PFAS or other substances under Section 102(a), but not without limits. It appears that future designations will require a substance-specific scientific record, adequate notice, reasoned responses to significant comments, and a rational explanation for the agency’s decision.
Companies that manufacture, use, transport, treat, or dispose of PFOA, PFOS or other PFAS should evaluate how the upheld designations affect compliance and risk management practice, including release-reporting procedures, historical operations, waste management arrangements, and site investigation and management practices. The decision also reinforces the importance of PFAS diligence in acquisitions and real property transactions, where the scope of diligence and negotiated risk allocation may significantly affect both deal terms and post-closing exposure. Participation in future rulemakings also remains important, particularly where regulated parties can provide data concerning potential costs, exposure pathways and site-specific consequences.
Looking ahead, the decision may also have implications beyond CERCLA. Although designation as a CERCLA hazardous substance does not itself change the regulatory status of PFOA or PFOS under other environmental statutes, PFAS regulation is already developing under other programs. Under the Clean Water Act, PFAS monitoring requirements have begun appearing in National Pollution Discharge Elimination System permits, and EPA has recommended that permitting authorities incorporate PFAS monitoring and related conditions where appropriate. Under the Resource Conservation and Recovery Act (RCRA), which governs the management of hazardous and non-hazardous solid waste, EPA has proposed listing nine PFAS, including PFOA and PFOS, as hazardous constituents. This would facilitate consideration of those substances under the RCRA corrective action program. The D.C. Circuit’s decision may provide additional momentum for these and other PFAS regulatory initiatives, although any further requirements would arise under the standards and processes applicable to those separate statutory programs.
Pillsbury’s Environmental and Natural Resource practice is focused on the practical implications of this evolving PFAS landscape across regulatory programs, including CERCLA, the Clean Water Act and RCRA. Our work encompasses PFAS-related permitting, waste management, site investigation and remediation, natural resource damages assessments and consent decrees, National Priorities List listing decisions, cost recovery actions, private contribution litigation, and administrative and civil settlements, as well as the identification, evaluation and allocation of PFAS-related environmental risks and liabilities in commercial agreements and transactions, mergers and acquisitions, and real estate transactions. For more information about how these developments may affect your business or operations, please contact the authors.