On April 13, 2023, the United States Environmental Protection Agency (“EPA”) published an Advanced Notice of Proposed Rulemaking (“ANPRM”) in the Federal Register that requested comments on whether EPA should consider designating certain  per- and polyfluoroalkyl substances (“PFAS”) as “hazardous substances” under the Comprehensive Environmental Response, Compensation, and Liability Act (“CERCLA”) in addition to perfluorooctanoic acid (“PFOA”) and perfluorooctanesulfonic acid (“PFOS”).  As we discussed in a previous post, EPA has already proposed to designate PFOA and PFOS as “hazardous substances,” which EPA anticipates finalizing sometime in 2023.

In this ANPRM, EPA is seeking comments and information on potentially designating the following PFAS as CERCLA “hazardous substances”:

  • Perfluorobutanesulfonic acid (“PFBS”), Perfluorohexanesulfonic acid (“PFHxS”), Perfluorononanoic acid (“PFNA”), Hexafluoropropylene oxide dimer acid (“HFPO–DA”), Perfluorobutanoic acid (“PFBA”), Perfluorohexanoic acid (“PFHxA”), and Perfluorodecanoic acid (“PFDA”);
  • Precursors to PFOA, PFOS, and the 7 PFAS listed above;
  • “Categories” of PFAS.

EPA notes that it has selected these 7 PFAS compounds because of the availability of toxicity information.  For example, in April 2021 and 2022, EPA issued final human health toxicity assessments for PFBS (Human Health Toxicity Values for Perfluorobutane Sulfonic Acid (CASRN 375–73–5) and Related Compound Potassium Perfluorobutane Sulfonate (CASRN 29420–49–3), Gen X (Final Human Health Toxicity Values for Hexafluoro-propylene Oxide (HFPO) Dimer Acid and its Ammonium Salt, CASRN 13252– 12–6 and CSRN 62037–80–3), and PFBA (IRIS Toxicological Review of Perfluorobutanoic Acid (PFBA) and Related Salts).

As to “Categories of PFAS,” EPA states that it is considering whether to initiate a future action to designate categories or groups of PFAS as “hazardous substances,” and will consider characteristics such as chemical structure (e.g., carbon chain length or functional group), physical and chemical properties, mode of toxicological action, precursors or degradants, or co-occurrence.  Comments must be received by EPA on or before June 12, 2023.