D.C. Circuit Upholds PFOA and PFOS CERCLA Designations—But Leaves Key Liability Questions Open

The D.C. Circuit has rejected the industry challenge to EPA’s designation of PFOA and PFOS as hazardous substances under CERCLA. In Chamber of Commerce of the United States v. EPA, No. 24-1193 (D.C. Cir. Aug. 18, 2026), a unanimous panel denied the consolidated petitions for review and left EPA’s 2024 rule in place. The immediate result is straightforward: PFOA and PFOS remain CERCLA hazardous substances.

But the decision leaves many of the questions that will determine actual PFAS liability for another day. The court did not define the outer boundary of what constitutes a “substantial danger” under CERCLA § 102(a), did not decide whether EPA must consider costs when making future hazardous-substance designations, and did not decide when a particular downstream recipient will be liable for PFAS contamination at a particular site. Those unresolved questions may ultimately matter more to regulated businesses than the validity of the designation itself.

What the Court Held

EPA’s 2024 rule, published at 89 Fed. Reg. 39,124, designated PFOA and PFOS, including their salts and structural isomers, under CERCLA § 102(a), 42 U.S.C. § 9602(a). The rule became effective July 8, 2024 and established a one-pound reportable quantity. Section 102(a) directs EPA to designate substances that, when released into the environment, “may present substantial danger” to public health, welfare, or the environment. Petitioners argued that EPA’s reading of “may” allowed designation based on too much uncertainty.

The court disagreed.  Applying Loper Bright Enterprises v. Raimondo, the panel independently interpreted the statute rather than deferring to EPA. It endorsed EPA’s “plain meaning” interpretation and rejected Petitioners call for a bright-line “substantial danger” threshold, The court concluded that “may” addresses the possibility of substantial harm, not certainty that serious harm will follow every release. The decision supports the EPA’s discretion to designate more PFAS chemicals as CERCLA “hazardous substances” rather than limiting it. At the same time, the court emphasized that EPA’s authority is not unlimited. The phrase “substantial danger,” it said, has “real bite”: the danger must be serious and real, rather than hypothetical. The court did not attempt to define precisely where that line falls because petitioners did not dispute that PFOA and PFOS satisfy the standard. This leaves unresolved what constitutes a “substantial danger” for future § 102(a) designations involving substances with less developed or more disputed scientific records.

The panel also rejected petitioners’ argument that CERCLA creates a simple hierarchy in which a “hazardous substance” must necessarily be more dangerous than a “pollutant or contaminant.” The court found that the two categories operate differently. CERCLA § 104(a)(1) allows EPA to respond to a pollutant or contaminant when a particular release “may present an imminent and substantial danger.” Section 102(a), by contrast, permits EPA to designate a substance generally when releases may present “substantial danger,” without the same imminence requirement. There is also a procedural distinction. Pollutants or contaminants can be addressed site by site. Hazardous-substance designation occurs by regulation and then applies across CERCLA sites. Borrowing the Supreme Court’s description in Atlantic Richfield Co. v. Christian, the panel characterized CERCLA as taking a “belt and suspenders approach”: a substance may first be addressed as a pollutant or contaminant and later be designated as a hazardous substance as scientific knowledge develops. That point may be important for other PFAS compounds that have not yet been designated under § 102(a). The court also rejected petitioners’ nondelegation and vagueness challenges.

EPA Won the Cost Challenge, But an Important Question Remains Open

Petitioners also challenged EPA’s consideration of the economic consequences of designation. EPA released an Economic Assessment in August 2022 and published the proposed rule the following month. When EPA finalized the designation in 2024, it issued a more developed Regulatory Impact Analysis. The court held that the final analysis was a permissible “logical outgrowth” of the earlier Economic Assessment and notice-and-comment process which did not require a second notice and comment period. EPA had already put its economic analysis before the public and requested comment on the treatment of costs.

The panel also rejected petitioners’ arbitrary-and-capricious challenges to EPA’s analysis of cleanup costs and other economic consequences. It separately rejected their Regulatory Flexibility Act challenge, concluding that the statute did not require EPA to account for every indirect small-business cost that might result from later and uncertain cleanup, liability, or allocation decisions.

But the court expressly left one larger legal issue unresolved: whether CERCLA § 102(a) requires EPA to consider costs at all when designating a hazardous substance. EPA assumed for purposes of the rulemaking that it should consider costs, and the court made the same assumption without deciding whether the statute actually requires it. That issue could become important as EPA develops its planned § 102(a) Framework Rule for future hazardous-substance designations.

What Hazardous-Substance Status Actually Changes

PFOA and PFOS were not completely outside CERCLA before the 2024 rule. EPA could address them as “pollutants or contaminants” under § 104 when the statutory conditions for such a response were satisfied. Hazardous-substance status, however, brings additional CERCLA authorities into play. Section 106 authority to compel cleanup applies to hazardous substances, and § 107 can permit recovery of qualifying response costs from responsible parties. As the D.C. Circuit explained, that cost-recovery mechanism is not available for a response involving substances solely in their capacity as pollutants or contaminants.

Designation also carries direct regulatory consequences. Releases meeting or exceeding one pound of PFOA or PFOS, including their salts or structural isomers, during a 24-hour period can trigger CERCLA § 103 and EPCRA § 304 reporting. Reporting is triggered by knowledge of a qualifying release; EPA has said these provisions do not independently require testing or continuous monitoring to determine whether the threshold has been met. CERCLA also imposes notice requirements in connection with certain transfers of contaminated federal property, and hazardous-substance designation has federal hazardous-material transportation consequences.

But designation alone does not establish CERCLA liability or automatically require a cleanup. A claimant still must establish the applicable elements of liability against a person within § 107(a), and response decisions remain site-specific. That distinction matters for waste handlers, wastewater utilities, landfills, recyclers, contractors, property owners, and others that may encounter PFAS without having manufactured it.

Passive Receivers Still Do Not Have a Statutory Safe Harbor

Passive-receiver concerns were squarely before the court. A group identifying itself as “Passive Receivers” filed an amicus brief supporting remand. The court nevertheless upheld the designation. EPA’s PFAS CERCLA enforcement-discretion policy attempts to address some of those concerns administratively. EPA says it intends to focus enforcement on parties that significantly contributed to PFAS releases, including PFAS manufacturers, parties that used PFAS in manufacturing processes, federal facilities, and other industrial parties.

EPA underscored the limits of administrative discretion in September 2025, stating that new statutory language from Congress would be needed to fully address passive-receiver liability. The D.C. Circuit’s decision does not change that. It holds that passive-receiver concerns do not invalidate EPA’s designation; it does not hold that passive receivers are immune from CERCLA claims.

What Companies Should Do Now

The D.C. Circuit’s decision affects real-estate diligence. Because PFOA and PFOS are now CERCLA hazardous substances, they fall within the hazardous-substance framework of ASTM E1527-21. Parties relying on Phase I Environmental Site Assessments should therefore confirm that consultants are evaluating plausible historical sources of PFOA and PFOS rather than treating all PFAS as categorically outside the Phase I process.

Finally, companies should preserve the records they have. CERCLA defenses, landowner protections, divisibility arguments, contribution claims, and equitable allocation positions can turn on historical facts that become more difficult to reconstruct with time.

What Comes Next

Chamber of Commerce resolves the principal challenge to EPA’s authority to designate PFOA and PFOS. It does not resolve how CERCLA will apply at a particular PFAS site. Future disputes are likely to involve familiar CERCLA questions in a difficult factual setting: identifying sources of highly mobile contaminants, establishing arranger or transporter liability, addressing divisibility, allocating response costs among parties with very different contributions, and determining what liability attaches to downstream receipt of PFAS-containing wastes or wastewater.

Future § 102(a) designations may also test the boundary the court declined to draw here: how much evidence is enough to establish “substantial danger” when the scientific record is less clear than it was for PFOA and PFOS.

Further review of Chamber of Commerce remains possible through rehearing or a petition for certiorari. For now, however, the operative rule is unchanged. PFOA and PFOS remain CERCLA hazardous substances. The harder questions now are the traditional CERCLA questions: who is responsible, for what release, at what site, subject to what defense or limitation, and for what share of the resulting costs.

This article is provided for general informational purposes only and does not constitute legal advice.