Drinking Water Health Advisories for GenX Chemicals and PFBS

2022 Final Health Advisories for GenX Chemicals and PFBS

Drinking water health advisory levels are non-regulatory health-based values that are provided for informational purposes . On June 15, 2022, the EPA published final drinking water health advisories (HAs) for perfluorobutane sulfonic acid and its potassium salt (PFBS) and hexafluoropropylene oxide dimer acid (HFPO-DA) and its ammonium salt (“GenX chemicals").

In chemical and product manufacturing, GenX chemicals are considered a replacement for perfluorooctanoic acid (PFOA), and PFBS is considered a replacement for perfluorooctane sulfonic acid (PFOS).

These two HA values are based on final the EPA toxicity assessments published in 2021. The 2022 health advisory documents for PFBS and GenX chemicals provide the lifetime noncancer HA value as well as information on treatment and analytical methods that may be useful to stakeholders.

At the same time, the EPA issued interim updated drinking water health advisories (iHAs) for PFOA and PFOS that replaced those the EPA issued in 2016.

On April 10, 2024, the EPA announced the final National Primary Drinking Water Regulation (Final PFAS NPDWR) for six PFAS, including PFBS and GenX chemicals (specifically, HFPO-DA). The EPA’s NPDWR established legally enforceable levels, called Maximum Contaminant Levels (MCLs) including individual MCLs for PFOA, PFOS, PFHxS, PFNA, and HFPO-DA, and a PFAS mixtures MCL containing at least two or more of PFHxS, PFNA, HFPO-DA, and PFBS.

• Federal Register Notice on Lifetime Drinking Water Health Advisories for Four Perfluoroalkyl Substances (June 21, 2022)
• Drinking Water Health Advisory: Hexafluoropropylene Oxide (HFPO) Dimer Acid (CASRN 13252-13-6) and HFPO Dimer Acid Ammonium Salt (CASRN 62037-80-3), Also Known as “GenX Chemicals”
• Final Human Health Toxicity Values for Hexafluoropropylene Oxide (HFPO) Dimer Acid and Its Ammonium Salt (CASRN 13252-13-6 and CASRN 62037-80-3) Also Known As “GenX Chemicals”
• Drinking Water Health Advisory: Perfluorobutane Sulfonic Acid (CASRN 375-73-5) and Related Compound Potassium Perfluorobutane Sulfonate (CASRN 29420-49-3)
• Human Health Toxicity Values for Perfluorobutane Sulfonic Acid (CASRN 375-73-5) and Related Compound Potassium Perfluorobutane Sulfonate (CASRN 29420-49-3)