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🚰EPA Announces Preliminary Regulatory Determinations for Water Contaminants

The Safe Drinking Water Act (SDWA), as amended in 1996, requires that the U.S. Environmental Protection Agency (EPA) determine whether to regulate at least five unregulated contaminants every five years. The decision to regulate or not to regulate a contaminant is known as a regulatory determination. In most cases, the contaminants chosen for regulatory determination are selected from the most recent Contaminant Candidate List (CCL), which the SDWA requires the EPA to publish every five years. This document presents the preliminary regulatory determinations and supporting rationale for contaminants listed on the EPA's fifth CCL (CCL 5). Since the fourth round of regulatory determinations was published in March 2021, the EPA has made determinations to regulate per- and polyfluoroalkyl substances (PFAS), including individual determinations for three PFAS: perfluorononanoic acid (PFNA), perfluorohexanesulfonic acid (PFHxS), hexafluoropropylene oxide dimer acid and its ammonium salt (HFPO-DA, also known as GenX or GenX chemicals); and mixtures including two or more of these three PFAS and perfluorobutanesulfonic acid (PFBS). In April 2024, the agency issued a final National Primary Drinking Water Regulation that includes these four PFAS as well as perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS). In this Federal Register Notice (FRN), the EPA is making preliminary determinations not to regulate nine additional contaminants from CCL 5: 2-aminotoluene, cylindrospermopsin, ethoprop, microcystins, molybdenum, permethrin, profenofos, tebuconazole and tribufos. The EPA requests public comment on these preliminary determinations and other aspects of this FRN. The EPA also presents updates on additional contaminants from CCL 5, as well as on some of those that have been considered in previous rounds of regulatory determinations and for which the EPA has not yet made a regulatory determination. The agency is also presenting and requesting comment on the process and analyses used for this round of regulatory determinations (i.e., RD 5), the supporting information, and the rationale used to make these preliminary decisions.