Articles Posted in Maximum Contaminant Levels (MCLs)

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On May 14, 2025, EPA announced its intent to rescind the national drinking water standards for hexafluoropropylene oxide dimer acid (HFPO-DA or GenX), perfluorononanoate (PFNA), and perfluorohexanesulfonic acid (PFHxS), as well as the hazard index used to evaluate the combined risk of those compounds and perfluorobutane sulfonic acid (PFBS). These Maximum Contaminant Levels (MCLs) were finalized in April 2024 under the prior administration. EPA says it will reconsider the regulatory determinations “to ensure that the determinations and any resulting drinking water regulation follow the legal process laid out in the Safe Drinking Water Act” (SDWA).

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On April 10, 2025, at the request of the Environmental Protection Agency (EPA), the U.S. Court of Appeals for the District of Columbia Circuit extended the stay by 30 days in American Water Works Association, et al. v. EPA, No. 24-1188 (D.C. Cir. 2024) to give new leadership time to evaluate the maximum contaminant levels (MCLs) established for six PFAS under the Safe Drinking Water Act. 89 Fed. Reg. at 32,532-33; 40 C.F.R. §§ 141.900-905. The court had previously granted EPA’s February 7 request for a 60-day stay to allow for initial review of the rule. The EPA has until May 12, 2025, to file future motions in the MCL challenge.

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