Scientific Overview of PFAS and Drinking Water | AAAS EPI Center
The EPA Developed Lifetime Health Advisory Levels for PFOS and PFOA Following UCMR 3, the EPA established non-enforceable lifetime health advisory levels for PFOS and PFOA in 2016. The lifetime health advisory level for PFOS and PFOA is 70 ng/L (or 70 ppt) based on the estimated exposure for the most at-risk population — pregnant and nursing women. The lifetime health advisory assumes a drinking water consumption of 0.054 liters per kilogram of body weight per day and that drinking water consumption makes up 20% of a human’s PFOS and PFOA exposure. However, exposure can be higher in areas with PFOS and PFOA present in drinking water supplies. Additional details regarding these assumptions are provided in EPA’s Drinking Water Health Advisories for PFOA and PFOS webpage 28 . The EPA Is Taking Steps Toward Establishing a Drinking Water Standard for PFAS The EPA developed a PFAS Action Plan in 2019 to advance its support for cleanup efforts, toxicology, monitoring in drinking water, emerging research, cleanup enforcement, and risk communication 29 . One of the major provisions of the Action Plan was to decide, by the end of 2019, whether to regulate PFOS and PFOA under the SDWA 30 . In February 2020, the EPA made a preliminary determination to regulate PFOS and PFOA. After review of the public comments received on this determination, the EPA must issue a final determination. If the EPA chooses to proceed with the regulatory process laid out in the SDWA, it will have up to 4.25 years to establish MCLs. As part of the PFAS Action Plan, EPA also will consider whether there is a need to regulate PFAS beyond PFOS and PFOA. Regulating PFAS by Chemical Characteristics Some experts and environmental advocates suggest regulating PFAS as a class rather than each chemical individually (i.e., establishing a single drinking water standard for the entire PFAS family). Other potential regulatory strategies include regulating groups of PFAS, also referred to as subclasses, that have similar chemical properties (e.g., perfluorinated carbon chain length, functional groups, degradation products), common adverse health effects, co-occurrence with other PFAS, or a combination of these characteristics. States Are Developing PFAS Guidance In the absence of enforceable federal regulations, several states have set MCLS for drinking water, and other states are in the process of doing so 31 . Federal and state PFAS health advisory levels, MCLs (established and proposed), guidance levels, and action levels differ due to the various toxicological endpoints and assumptions used in referenced studies. The EPA and states use toxicological evaluations (both federal- and state-conducted studies) to determine PFAS toxicity. For example, the EPA used a developmental endpoint for PFOA and PFOS exposure, whereas some states use a liver or an immune endpoint 32 . Additionally, some states have set levels for additional PFAS (besides PFOA and PFOS) that were determined to have adverse health effects or be more heavily present in drinking water supplies. For a complete list of state and federal PFAS guidance, please visit the ITRC and American Water Works Association (AWWA) PFAS regulation summaries 33,34 .
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