Rescission of Regulatory Determinations and Removal of Related Provisions for Four PFAS Substances (PFHxS, PFNA, HFPO-DA (GenX), and the mixture of these three PFAS plus PFBS)

The EPA is proposing to withdraw its regulatory determinations to regulate four per- and polyfluoroalkyl substances (PFAS)—perfluorohexane sulfonic acid (PFHxS), perfluorononanoic acid (PFNA), hexafluoropropylene oxide dimer acid and its ammonium salt (HFPO-DA, commonly known as GenX chemicals), and the mixture of these three PFAS plus perfluorobutane sulfonic acid (PFBS)—under the Safe Drinking Water Act. The EPA is also proposing to rescind all associated regulatory provisions currently codified in 40 CFR part 141 exclusive to these PFAS that were promulgated pursuant to these regulatory determinations. This action is being proposed solely on legal and procedural grounds. Related to Docket EPA-HQ-OW-2022-0114 and EPA-HQ-OW-2025-1742