On February 20, 2020, the U.S. Environmental Protection Agency (EPA) announced its intent to publish a preliminary regulatory determination under the Safe Drinking Water Act (SDWA) for perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS). Publication will initiate a 60-day notice and comment period that represents the first step toward the adoption of Maximum Contaminant Levels (MCLs) and Maximum Contaminant Level Goals (MCLGs) for PFOA and PFOS, two of the best-understood and most common compounds under the umbrella of perfluoroalkyl substances (PFAS).
If EPA issues a final determination that these substances should be regulated following review and consideration of public comment, the SDWA requires EPA to propose MCLGs and MCLs within two years. Those standards will then be subject to a separate notice-and-comment process before they can be adopted. Notably, EPA has chosen a sequential approach to adopting regulations; EPA could have proposed numerical MCLs and MCLGs and published its preliminary regulatory determination simultaneously. The preliminary regulatory determination also specifies six contaminants that it proposes not to regulate: 1,1-dichloroethane, acetochlor, methyl bromide (bromomethane), metolachlor, nitrobenzene, and RDX.
As readers might recall from our discussion of the PFAS Action Plan, EPA published non-binding health advisory levels for PFOA and PFOS in drinking water (70 ppt individually or combined) in 2016. Neither health advisory levels nor MCLGs result in enforceable drinking water standards, but they can influence remedial actions under the Comprehensive Environmental Response Compensation and Liability Act (CERCLA). They also influence state policy; dozens of states have adopted or proposed MCLs at or below the level specified in the EPA health advisory for PFOA and PFOA. MCLs, in contrast, are enforceable limits that public water systems must not exceed, but that are informed by consideration of feasibility. For instance, MCLGs could be set as low as zero, but consideration of the cost and efficacy of available treatment technology could result in the adoption of MCLs that are above the level specified in the 2016 health advisory. Once MCLs are adopted, they must go into effect within three years, subject to extensions of up to two years.
Notably, while the proposed determinations address only PFOA and PFOS, EPA is also using their publication to gather input on “regulatory constructs and monitoring requirements” for PFAS more broadly. Specifically, EPA will request comments on whether it should evaluate PFAS compounds individually or as larger classes of compounds, based on such factors as chain length, functional groups, degradation products, co-occurrence, or fate-and-transport. EPA also intends to ask whether it should promulgate required treatment techniques for PFAS in lieu of MCLs, as the SDWA allows it to do if achieving an MCL is not feasible. Finally, EPA will seek input on a variety of possible monitoring approaches for PFAS in drinking water—including whether monitoring should be required for public water systems near likely PFAS sites, such as facilities that used certain fire-fighting foams (like an Air Force base or refinery) or facilities that manufacture products using PFAS.
The proposed determinations have not yet been published in the Federal Register, but comments will be due 60 days after publication. We will update readers further when we learn more.