WASHINGTON, D.C., August 19, 2026– A federal appeals court on Tuesday rejected an industry-led challenge to the Environmental Protection Agency’s 2024 rule classifying two of the most widely studied PFAS compounds as hazardous substances under the nation’s Superfund law, handing the agency a decisive win in one of the most closely watched environmental cases of the year.
By a unanimous ruling, a three-judge panel from the U.S. Court of Appeals for the District of Columbia Circuit has rejected all the arguments raised against EPA’s designation of PFOA and PFOS as hazardous substances under CERCLA, otherwise referred to as Superfund. The case was filed by the U.S. Chamber of Commerce together with six other organizations, which include the American Chemistry Council and the National Waste & Recycling Association, arguing that EPA exceeded its authority and based its cost-benefit analysis on an incorrect basis.
Judge Patricia Millett, who authored the opinion, wrote that the agency “made a reasoned decision on the record before it in designating the forever chemicals PFOA and PFOS as hazardous substances,” even while acknowledging some scientific uncertainties. Judges Gregory Katsas and Neomi Rao joined the ruling.
The petitioners advanced three main points in their case. The first was that EPA cannot deem a substance hazardous until it can prove that there is certainty that harm will result from any release of it. Second, that EPA failed to provide sufficient notice with respect to its cost-benefit analysis and third, that its reasoning does not reach the level needed for making such an important decision. The court disagreed with each point, stating that the use of the word “may” in the statute indicates a probability standard, not certainty, and that EPA’s final economic analysis is a fair development of what EPA circulated for comment.
Both of these chemicals were classified as being hazardous for the very first time in the year 2024, owing to the findings of studies conducted on their carcinogenic nature as well as developmental disorders. PFOA and PFOS are members of an enormous group of PFAS compounds, known as “forever chemicals” due to their persistence in the environment and ability to build up in the human body. These compounds have been used in non-stick cookware, water-repellent materials, and firefighting foam for decades and were found in drinking water, fish, and people’s blood nationwide.
The decision means that the designation is fully legally binding now. Any company releasing over one pound of the substance will be obliged to report it to the federal authorities, while companies connected with the sites of contamination (producers, disposal operators, and property owners) may be held responsible for the costs of remediation pursued by the EPA, states, or other entities.
Reaction split sharply along expected lines. An attorney with the environmental legal group Earthjustice called the decision “a major win for contaminated communities across the country”. The Chamber of Commerce, meanwhile, said it disagreed with the outcome, arguing the agency’s failure to weigh costs adequately would produce “unnecessary, costly litigation” rather than efficient cleanup. The group has not said whether it will seek review from the U.S. Supreme Court, though legal observers say a certiorari petition would not be surprising given the rule’s scope.
The decision leaves several questions unresolved, including whether CERCLA actually requires EPA to weigh costs before designating a hazardous substance in the first place, a question both the agency and the court assumed without deciding. With more than 9,000 known PFAS compounds still unregulated under federal hazardous-substance law, attorneys who track the issue say Tuesday’s ruling is unlikely to be the last major legal battle over how the chemicals are handled.
