The U.S. Environmental Protection Agency (EPA) issued four lifetime health advisories1 for several per- and polyfluroroalkyl substances (PFAS) on June 15, 2022. Health advisories issued for two contaminants – perflurooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) – replaced and drastically lowered health advisory levels (HALs), which EPA had published approximately six years ago. In May 2016, EPA had set the HAL for individual or combined concentrations of PFOA and PFOS at 70 parts per trillion ("ppt"). The June 2022 HAL for PFOA is 0.004 ppt – a level 17,500 times lower than the May 2016 HAL. For PFOS, the June 2022 HAL is 0.02 ppt, a level 3,500 times lower than the May 2016 HAL. The two remaining PFAS-related health advisories EPA published on June 15, 2022 – for GenX chemicals2 and for PFBS3 – were entirely new and were set at 10 ppt and 2,000 ppt respectively.
What are PFAS?
PFAS are a group of synthetic chemical compounds that came into wide use in the 1940s. Many PFAS consist of carbon and fluorine atoms linked together in chains of various sequences and lengths. These chemical bonds resist degradation and thermal extremes. As a result, PFAS persist in the environment and bioaccumulate in the human body, where they can remain for a long time. PFOA and PFOS are each long-chain PFAS. They are among the most studied PFAS and are thought to be so widespread that some state regulators have said they are ubiquitous in the environment. U.S. manufacturers largely stopped using PFOA and PFOS in the mid-2000s as the industry made shorter-chain compounds to replace those longer-chain PFAS. GenX chemicals and PFBS are shorter-chain PFAS and were developed replace PFOA and PFOS respectively.
HALs for PFAS and PFOS are now so low that they "are below the level of both detection (determining whether or not a substance is present) and quantitation (the ability to reliably determine how much of a substance is present). This means that it is possible for PFOA or PFOS to be present in drinking water at levels that exceed health advisories even if testing indicates no level of these chemicals."4 The same statement cannot be made about HALs for the GenX chemicals and PFBS: they "are above both the detection and quantitation levels, and therefore can be reliably measured using specified analytical methods in appropriate laboratory settings."5 EPA evaluated "over 400 peer-reviewed studies published since 2016" and concluded that "the levels at which negative health effects could occur are much lower than previously understood when EPA issued the 2016 Health Advisories for PFOA and PFOS (70 ppt) – including near zero for certain health effects."6
Unlike the HALs for the GenX chemicals, which EPA considers to be final, the HALs for PFOA and PFOS are "interim" HALs. That interim is "the time interval between initial understanding of health effects and publication of the final health advisory or maximum contamination level goa (MCLG) and National Primary Drinking Water Regulation."7 EPA seeks to propose a National Primary Drinking Water Regulation (NPDWR) for PFOA and PFOS by the end of 2022 and to finalize those regulations by the end of 2023. "NPDWRs include legally-enforceable Maximum Contaminant Levels (MCLs) and/or treatment technique requirements that apply to" public water systems as defined by the Safe Drinking Water Act.8 Once NPDWRs are finalized for PFOA and PFOS, EPA may update or remove the health advisories that were published for these two PFAS on June 15, 2022.
In the meantime, however, the "health-based water values" established for PFOA and PFOS "are likely to remain below the detection limit."9 As EPA moves towards proposing NPDWRs for PFOA and PFOS, the final MCL or treatment technique that emerges will need to consider not just the impacts on human health (which led to these health advisories) but the practicality of assuring the reduction or elimination of the amount of either of these PFAS in drinking water. States that have not yet exercised their authority to propose their own MCLs may continue to wait to see where EPA will now go.
1 The federal Safe Drinking Water Act, as amended, 42 U.S.C. § 300f et seq., authorizes EPA to issue health advisories, "which are not regulations" but are instead informational statements about "contaminants not subject to any national primary drinking water regulation." 42 U.S.C. § 300g-1(b)(1)(F). In a health advisory, EPA may state a non-enforceable concentration "at which adverse health effects are not anticipated to occur over specific exposure durations, such as one-day, 10-days or a lifetime."
2 The GenX chemicals are hexafluoropropylene oxide (HFPO) dimer acid and HFPO dimer acid ammonium salt.
3 PFBS refers to perfluorobutane sulfonic acid and a related compound, potassium perfluorobutane sulfonate.
4 See EPA answer to Question 7 ( EPA Q&A).
5 EPA Q&A at Question 7.
6 EPA Q&A at Question 10.
7 EPA Q&A at Question 9.
8 See Section 1.0 of the Interim Drinking Water Health Advisories for PFOA and PFOS published on June 15, 2022.
9 EPA Q&A at Question 10.
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