Recent US State and Federal Drinking Water Guidelines for Per‐ and Polyfluoroalkyl Substances

Abstract

Per-and polyfluoroalkyl substances (PFAS), a class of synthetic chemicals produced for over 70 years, are of increasing concern because of their widespread environmental presence, extreme persistence, bioaccumulative nature, and evidence for health effects from environmentally relevant exposures. In 2016, the United States Environmental Protection Agency (USEPA) established nonregulatory drinking water Health Advisories of 70 ng/L for individual and total concentrations of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS), the 8-carbon perfluoroalkyl acids (PFAAs) that are the most thoroughly studied PFAS. As of May 2020, 9 US states had concluded that the USEPA Health Advisories are insufficiently protective and developed more stringent PFOA and PFOS guidelines. In addition, 10 states had developed guidelines for other PFAS, primarily PFAAs. This Critical Review discusses the scientific basis for state and USEPA drinking water guidelines for PFOA and PFOS; the same principles apply to guidelines for other PFAS. Similarities and differences among guidelines arise from both toxicity and exposure considerations. The approximately 4-fold range among state guidelines (8-35 ng/L for PFOA, 10-40 ng/L for PFOS) is not large or unexpected for guidelines developed by different scientists at different time points, especially when compared with older USEPA and state guidelines that were generally several orders of magnitude higher. Additional state guidelines for PFOA, PFOS, and other PFAS are expected to become available.

Per‐ and Polyfluoroalkyl Substance Toxicity and Human Health Review: Current State of Knowledge and Strategies for Informing Future Research

“…Experimental studies of PFAS have been limited by funding and the availability of analytical standards, confounded by the prevalence of background contamination in laboratory materials, and challenged by physicochemical properties such as high surface activity that can interfere with and complicate measurements. Consequently, sufficient information to conduct quantitative risk assessment is currently available for only a relative few PFAS (Post 2020). Further, although typical human exposures involve various combinations of PFAS (Centers for Disease Control and Prevention 2017), only a few efforts address interactions of PFAS mixtures; and a well-founded, scientific basis on which to evaluate their combined toxic potential does not yet exist (Carr et al 2013;Wolf et al 2014;Zhou et al 2017;Hoover et al 2019; US Environmental Protection Agency 2020).…”

The Social Life of the “Forever Chemical”

“…In 2016, the EPA fi nally issued a health advisory of 0.07 ppb (or 70 ppt) for PFOA and PFOS in drinking water. In recent years, many toxicologists and activists have argued for a 1 ppt safety threshold for PFOA and PFOS, and many states test for dozens of additional PFAS chemicals and have recommended exposure limits much lower than the EPA's current advisories (Cordner et al 2019;Post 2021). As health-based thresholds are refi ned, more communities become classifi ed as having polluted water.…”

On Per‐ and Polyfluoroalkyl Substances: Suggested Resources and Considerations for Groundwater Professionals

“…Decisions on which compounds to regulate and to what concentration, and whether to regulate individually or as a class, fundamentally come down to differences in interpretation of the available technical information, the approaches used to address the uncertainty in those interpretations, and the level of risk that is considered acceptable when factoring in health, economic, and other considerations prioritized by a given regulatory body. In evaluating human health as an example, technical evaluations of the potential health risks posed by PFAS should consider how a person can become exposed; the amount of exposure that can occur; the age, sex, and susceptibility of the exposed person; the toxic effects that exposure could have; and if those toxic effects exceed a level of risk that is considered acceptable by the regulatory agency (Post 2020). Each of these steps requires consideration of a significant amount of available data related to occurrence, chemical fate and transport, resource use, modes of action, critical effects, dose–response, causality, relative potency, and myriad other factors.…”