On May 8, 2024, the U.S. Environmental Protection Agency (EPA) formally published in the Federal Register (89 Fed. Reg. 39124) its long-awaited final rule designating two of the most studied per- and polyfluoroalkyl substances (PFAS) as “hazardous substances” under the federal Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA, commonly known as Superfund), 42 U.S.C. § 9601 et seq. The two chemicals designated as “hazardous substances” are perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid  (PFOA), including their salts and structural isomers.

The most immediate and direct effects of this “hazardous substances” designation are that (1) facilities will be required to immediately report any release of PFOS or PFOA (or their salts and structural isomers) that meet or exceed the default reportable quantity of one pound within any 24-hour period to the National Response Center and to community emergency coordinators per the federal Emergency Planning and Community Right-to-Know Act (EPCRA); (2) facility owners must provide notice of releases of these chemicals through publication in the local newspaper; (3) facilities must also provide follow-up reports within 30 days to community emergency coordinators, per EPCRA; (4) federal agencies that sell or transfer property must also now provide notice of storage, release, or disposal of PFOS and PFOA on the property (along with a covenant warranting it has cleaned up, or will clean up as required, the past contamination); and (5) the Department of Transportation must begin to regulate PFOS and PFOA under the Hazardous Materials Transportation Act.

With the formal publication, the rule is set to go into effect on July 8, 2024 (60 days after publication), absent legal challenge. However, litigation to challenge the rule is likely and it could delay this effective date.

If the rule does become effective, here are four key takeaways about its immediate significance: 

• EPA’s Response Action Authority. Designating PFOS and PFOA as “hazardous substances” does not automatically require site listing under CERCLA or that parties take specific response actions. However, EPA makes clear that with this rule it has “broad discretionary authority to decide on a site-specific basis whether to respond to a release or threat of release and to prioritize the order in which it undertakes response actions determined to be necessary.” EPA has already used its authority under CERCLA’s “pollutants or contaminants” and “imminent and substantial endangerment” provisions to require testing, monitoring, and some remedial action at Superfund sites where certain PFAS were identified. However, according to EPA, listing PFOS and PFOA as “hazardous substances” “streamlines response authority, provides a mechanism for parties to recover response costs from [potentially responsible parties (PRPs) at Superfund sites], and makes available CERCLA enforcement authority to compel PRPs to conduct or pay for cleanup.”  

• Potential to Re-Open Superfund Sites. A core concern raised during the public comment period on the rule was whether EPA would review Superfund sites that have already been remediated for other contamination and “re-open” them to investigate for past PFOS or PFOA contamination. EPA notes that past and existing PFOS and PFOA contamination is likely extensive given the scale of use and releases in the past–“PFOA and PFOS were historically manufactured on a broad scale, have past and continued releases to the environment (e.g., through legacy disposal, release of precursors, or manufacture as a byproduct), and are detected widely in multiple environmental media, including groundwater, surface water, wild animals, livestock, and plants.” EPA acknowledges that it will have the authority to consider re-opening previously closed or dormant Superfund sites to address PFOS and PFOA contamination, but it does not indicate how (or how frequently) it will consider taking this step. In the final rule itself and the agency’s “questions and answers” webpage on the rulemaking, EPA states that it will likely use CERCLA’s “five-year review” process at sites to “evaluate whether the remedy can mitigate any unacceptable risk from PFOA or PFOS contamination or whether additional actions may need to be taken.” Based on the five-year review process, “[i]n some cases, it may be necessary to revise or expand the previous risk assessment … For example, the risk assessment may need to be revised when there is a new exposure pathway, a new potential contaminant of concern, or an unanticipated toxic byproduct of the remedy. Five-year reviews [] can also recommend further investigation to determine whether an additional response action is needed.”

• EPA’s Enforcement Discretion Guidance. In tandem with the final rule, EPA also released a guidance memorandum addressed to all EPA regions regarding the agency’s CERCLA PFAS enforcement discretion policy. The memorandum states that EPA’s highest priority for PFAS enforcement against potentially responsible parties for response actions or to recover response costs is “responsible entities who significantly contributed to the release of PFAS into the environment, including parties that manufactured PFAS or used PFAS in the manufacturing process, federal facilities, and other industrial parties” (so-called “major PRPs” for the purposes of this guidance). At the same time, EPA states that equitable factors “do not support seeking response actions or costs under CERCLA” against a number of industry types, including “community water systems and publicly owned treatment works, municipal separate storm sewer systems, publicly owned/operated municipal solid waste landfills, publicly owned airports and local fire departments, and farms where biosolids are applied to the land.” For these entities, EPA states it may consider, where appropriate, entering into settlements that provide third-party contribution protection. EPA also indicates it may consider extending enforcement discretion to other, similarly situated industry types or parties when supported by equitable considerations.

• EPA Already Considering Designating Additional PFAS as “Hazardous Substances.” Designating PFOS and PFOA as “hazardous substances” is one component of EPA’s encompassing, “whole-of-agency” approach to PFAS regulation and enforcement, outlined in the 2021-2024 PFAS Strategic Roadmap and through identification of PFAS, for the first time, as one of EPA’s new National Enforcement and Compliance Initiatives for 2024-2027. In April 2023, EPA published an advanced notice of proposed rulemaking requesting input from the public and stakeholders on whether to list other individual PFAS, PFAS precursors, or whole categories of PFAS, as CERCLA “hazardous substances.” The request specifically identified seven additional PFAS, and categories of PFAS, it is considering for listing, including perfluorobutanesulfonic acid (PFBS); perfluorohexanesulfonic acid (PFHxS); perfluorononanoic acid (PFNA); hexafluoropropylene oxide dimer acid (GenX); perfluorobutanoic acid (PFBA); perfluorohexanoic acid (PFHxA); and perfluorodecanoic acid (PFDA). EPA references this request in the final PFOS and PFOA “hazardous substance” rule and says it is still reviewing and evaluating public input it received. Depending on the outcome of any litigation challenging the reasoning or technical justifications EPA used in the PFOS and PFOA rule, listing of these additional PFAS compounds may be the subject of future rulemaking (and likely future litigation).