Final Minimum Risk Levels for PFAS: What Do They Mean?

Madeline Fleisher
Dickinson Wright

In May 2021, the federal Agency for Toxic Substances and Disease Registry (ATSDR) finalized a report containing toxicological profiles and associated Minimal Risk Levels (MRLs) for several perfluoroalkyls (PFAS), a family of chemicals marked by their persistence in the environment, bioaccumulation in human and animal tissue, and toxicity at extremely low levels (in the parts per trillion).[1] You may have seen PFAS flagged as contaminants of concern at sites across the country or seen the film “Dark Waters” about PFAS toxic tort litigation. Whatever the context, you probably know that PFAS regulation and liability issues are evolving at a rapid pace. So what does ATSDR’s new report mean going forward?

Bottom line: this report sets the stage for what is likely to be a contentious battle regarding PFAS clean-up levels in the years ahead. Although the general potential for harmful effects from PFAS was identified several decades ago, definitive guidance on valid screening and cleanup levels for specific PFAS chemicals has lagged further behind as the science around PFAS toxicity and testing methodologies has developed. Prior to the ATSDR report, the U.S. Environmental Protection Agency (U.S. E.P.A.) had set a non-binding health advisory level of 70 parts per trillion (ppt) combined for perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) for lifetime chronic exposure and also issued a December 2019 interim recommendation for a 40 ppt combined PFOA/PFOS screening level for federal cleanup programs (leaving 70 ppt as a preliminary remediation goal). U.S. E.P.A. has yet to designate any PFAS chemical as a hazardous substance for purposes of the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) or a hazardous waste for purposes of Resource Conservation and Recovery Act (RCRA).[2]

In the absence of binding federal standards, state environmental regulators have followed various approaches to monitoring and responding to PFAS. Many states have conducted testing of major drinking water sources for PFAS, either on their own initiative or under U.S. E.P.A.’s Unregulated Contaminant Monitoring Regulation 3 requiring sampling under the Safe Drinking Water Act, but sampling of private wells and smaller non-community systems has been sporadic. Some states have developed screening and action levels lower than U.S. E.P.A.’s, while others have relied on the federal 70 ppt health advisory level as a credible number to guide agency action. Overall, this has created a patchwork of information and regulation across U.S. jurisdictions.