EPA Heads to Court to Defend PFAS Listing as Hazardous Substance

A coalition of industry groups will square off against the EPA in a federal appeals court Jan. 20 in a dispute over the legality of the agency’s decision to designate two PFAS as hazardous Superfund substances.

The industry coalition led by the US Chamber of Commerce wants the US Court of Appeals for the District of Columbia Circuit to vacate the Environmental Protection Agency’s final rule that designated two specific “forever chemicals,” perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS), as hazardous substances under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), or Superfund law.

The EPA based that designation on its conclusion that both chemicals “may present substantial danger to public health or welfare or the environment.”

But the rule makes property owners, manufacturers, and other parties potentially subject to CERCLA’s strict, retroactive, and joint and several liability provisions, because it makes it easier for states and the EPA to investigate and require cleanups of the chemicals.

The court should vacate the rule, because the EPA’s designation put no meaningful constraint on the substances that could become subject to CERCLA, wrote Elbert Lin, a partner with Hunton Andrews Kurth LLP, in the industry coalition’s final reply brief.

Defining Hazardous Substances

If there’s no fixed boundary for the EPA’s interpretation of what constitutes a hazardous substance, “than either (A) the agency’s interpretation is broader than Congress delegated, or (B) what Congress delegated was unconstitutional,” Lin said.

The 2024 rule marked the first time the EPA directly listed chemicals as hazardous substances under CERCLA. All previous chemicals subject to Superfund were first regulated under the agency’s waste law, the Resource Conservation and Recovery Act, or other statutes.

Congress didn’t require the EPA to define “fixed boundaries,” or thresholds, that would determine when substances become hazardous, wrote trial attorney Jin Hyung Lee, with the Department of Justice, which represents the EPA. “Congress conferred on EPA the authority to evaluate ‘substantial danger’ by weighing relevant factors as the agency did here.”

“EPA found strong links between PFOA and PFOS exposure and a myriad of serious adverse health effects, including several cancers, pregnancy complications, and harms to fetuses and children,” the EPA’s final brief said.

Both chemicals move easily through soil and water, pollute drinking water, and enter the food chain, it said.

“Releases of toxic, likely carcinogenic, bioaccumlative, extremely persistent, and highly mobile chemicals ‘may present substantial danger’ on any ordinary understanding of that phrase,” the EPA’s brief said.

Cost-Benefit Analysis

The cost-benefit analysis the EPA used to underpin the rule was fatally flawed, the industry brief said. For example, the agency failed to subject the analysis to public notice and comment, and its estimates ignored many costs, the industry brief said.

The agency’s proposed rule said it didn’t need to consider costs beyond the rule’s direct impact—estimated at $370,000—of requiring facilities releasing one pound or more of either chemical within 24 hours to notify the EPA of that release.

The agency’s final rule increased its estimated direct costs to be up to $1.6 million. And the agency estimated indirect costs, including potential enforcement, could range from $327,000 to $18.1 million annually.

The final cost analysis contains serious errors, including the EPA’s assertion that the rule won’t cause new cleanups of PFOA or PFOS at existing Superfund sites, the industry brief said.

The final rule will cause new cleanups, and therefore new costs, because the agency no longer will have to show a substances poses “imminent and substantial danger” before ordering cleanup and because the rule allows the agency to shift cleanup costs to potentially responsible parties, the brief said.

The agency also ignored billions of dollars of other significant costs landfills, water treatment plants, and other facilities would have to spend managing wastes with PFOA and PFOS, it said.

The EPA was not required to conduct a cost-benefit analysis for the rule, so it didn’t violate the Administrative Procedure Act, the EPA’s brief said.

The agency chose for its final rule to develop illustrative quantitative estimates of the costs associated with future remedial actions involving PFOA and PFOS, and those estimates “fall well ‘within the limits of reason and rationality,’” it said.

As to the “grab-bag” of waste management costs petitioners say the agency should have considered, the EPA’s brief said designating the two chemicals as hazardous substances does not impose specific waste management obligations pertaining to treatment, disposal, or storage.

Judges Patricia A. Millett, Gregory G. Katsas, and Neomi Rao are scheduled to hear the Jan. 20 oral arguments.

The case is Chamber of Commerce v. EPA, D.C. Cir., No. 24-01193, Final Briefs Filed, 12/5/25.