The D.C. Circuit has upheld EPA’s designation of two PFAS, perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS), as hazardous substances under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA). In Chamber of Commerce v. EPA, decided August 18, 2026, the court denied every petition challenging the designation, leaving the 2024 rule in place.
What the Court Decided
Industry petitioners, led by the U.S. Chamber of Commerce and joined by chemical, fuel, waste, recycling, construction, and paper trade associations, raised three lines of attack: (1) that EPA misread CERCLA’s “may present substantial danger” standard; (2) that its cost-benefit analysis violated the Administrative Procedure Act’s notice requirement and was arbitrary and capricious; and (3) that regulating amid scientific and economic uncertainty was itself unreasonable. The panel rejected all three.
Starting with the standard for designation, 42 U.S.C. § 9602(a) directs EPA to designate as hazardous those substances that, when released into the environment, “may present substantial danger to the public health or welfare or the environment.” Petitioners read that phrase to require a finding that harm will occur on release. Interpreting the statute de novo and without deference to EPA under Loper Bright Enterprises v. Raimondo, the court disagreed. “May” denotes possibility, not certainty, and the statute directs EPA to forecast the risk of harm at the time a substance is released, the court held. The phrase “substantial danger” means that the risk of harm must be serious and real, not hypothesized, which the court said answers the worry that EPA’s reading would let the agency reach something as innocuous as table salt. Requiring absolute certainty about every release, the court added, would paralyze a statute Congress designed to act on scientific probabilities.
The court rejected two related theories within the same challenge. First, it declined to read an inflexible hierarchy into CERCLA under which “hazardous substances” must clear a higher bar than “pollutants or contaminants.” The two are separate designation regimes, the court held, and a substance may begin as a pollutant or contaminant and later be designated a hazardous substance as the science develops. Second, the court found no nondelegation or void-for-vagueness problem. Tying EPA’s authority to scientific findings under a public-health standard supplies the “intelligible principle” the nondelegation doctrine requires, the decision states, and the prior regulation of PFOA and PFOS under CERCLA gave regulated parties fair notice that they could be listed.
On the notice challenge, the court held that EPA’s Regulatory Impact Analysis was a “logical outgrowth” of the earlier Economic Assessment, so the additional cost data introduced in the final rule required no fresh comment round. Notably, the court did not decide whether CERCLA requires EPA to weigh costs in a designation at all. EPA assumed it must, and the panel assumed the same without deciding, which leaves that question open for a future challenge.
As for regulating amid uncertainty, the court held that EPA acted reasonably in designating PFOA and PFOS despite acknowledged gaps in what it knows about where the chemicals are, what cleanup will cost, and the rule’s downstream effects. The decisive point was that designation is only the first of many steps before liability attaches. A long sequence of contingent regulatory actions, together with CERCLA’s statutory limits on liability, stands between listing a substance and any party actually bearing cleanup costs. Accordingly, the court concluded that EPA’s choice to regulate now rather than wait for certainty was not arbitrary and capricious.
Why It Matters
The designation, effective July 8, 2024, was EPA’s first use of 42 U.S.C. § 9602(a) to list a substance directly, rather than by reference to another environmental statute. Its practical consequences are now in force: releases of one pound or more of PFOA or PFOS in a 24-hour period trigger reporting obligations, federal property transfers carry notice duties, and most significantly, responsible parties face CERCLA’s strict, joint-and-several liability and cost-recovery regime.
The ruling reaches well beyond PFAS manufacturers. Waste management, recycling, construction, and other “passive receivers” that handled PFOA- and PFOS-containing materials without making them may now sit within the liability chain. As the court stressed in rejecting the uncertainty challenge, though, listing is not the same as liability: CERCLA’s defenses, including its act-of-God, third-party, de minimis, de micromis, and innocent-landowner provisions, continue to limit who ultimately pays.
What to Watch
The decision is recent, and the deadlines for a petition for rehearing en banc or a petition for certiorari have not yet run, so the litigation may not be over.
Several aspects of the ruling bear on future CERCLA designations. Because the court reviewed EPA’s reading de novo and still upheld it, the agency’s designation authority now rests on the statute’s best reading rather than on judicial deference, a firmer footing in the wake of Loper Bright. EPA committed to notice-and-comment rulemaking before updating this designation, and it has said it intends to develop a broader framework for § 9602(a) designations generally, though the scope and timing of any such rulemaking remain to be seen. And because the court left open whether cost must be weighed in a designation at all, that question is likely to return as EPA considers additional substances.
For background on the agency’s decision to defend the rule, see our previous post on the litigation.
The case is Chamber of Commerce v. EPA, No. 24-1193 (D.C. Cir.), filed June 10, 2024.
