Advisories Apply to PFOA, PFOS, GenX and PFBS
The Environmental Protection Agency (EPA) released new drinking water health advisories for four of the most common per- and polyfluoroalkyl substances (PFAS):
- Perfluorooctanoic acid (PFOA)
- Perfluorooctane sulfonate (PFOS)
- Hexafluropopropylene oxide dimer acid and its ammonium salt (GenX)
- Perfluorobutane sulfonic acid and its potassium salts (PFBS)
In this June 15 health advisory, the EPA recommends an interim lifetime exposure limit of 0.004 parts per trillion (ppt) for PFOA and 0.02 ppt for PFOS. The health advisory also recommends a final exposure limit of 10 ppt for Gen X and 2,000 ppt for PFBS.
Public water agencies in particular should monitor PFAS updates carefully, as they may be subject to new limits for PFAS entering their water or treatment biosolids.
Brief History of PFAS Federal Regulation
Under the Obama administration, the EPA set a 2016 health advisory for both PFOA and PFOS at a combined 70 ppt per day. In the fall of 2021, the EPA released the PFAS Strategic Roadmap (Roadmap). This multi-year plan contained EPA’s goals and priorities for addressing PFAS. The Roadmap drew out a plan for addressing PFAS from the beginning of the lifecycle of PFAS by reviewing and utilizing the science of PFAS. In this Roadmap, the EPA committed to providing updated health advisories in early 2022.
The EPA published toxicity assessments for GenX chemicals in late 2021. These assessments stated that oral ingestion of no more than 3 ppt per day would not impact the health of most people. Further, the toxicity assessments led the EPA to re-examine the standards set for PFOS, PFOA and PFBS. Following the release of the toxicity assessment, the EPA stated that oral ingestion of no more than 0.0015 ppt per day of PFOA and 0.0079 ppt per day of PFOS would not impact the health of most people. Because the EPA used an oral ingestion rate of 20 ppt per day to create the 70 ppt health advisory limit for both PFOA and PFOS, the EPA created a new lower health advisory limit.
EPA set the new interim health advisories for PFOA and PFOS at 0.004 ppt and 0.02 ppt respectively. These advisories are only interim because the EPA may update or remove them once the National Primary Drinking Water Regulation is finalized. The advisories are primarily based on epidemiological studies of seven-year-old human children with decreased immunity caused by PFOA and PFOS. This benchmark was selected because it was the most sensitive non-carcinogenic effect from the over 400 studies the EPA examined. These advisories assume that only 20% of lifetime exposure from PFOA and PFOS will come from drinking water.
EPA also set the final health advisories for GenX and PFBS at 10 ppt and 2,000 ppt respectively. These advisories are based on animal toxicity studies following oral exposure. The GenX advisory is based on data relating to adverse liver effects, while the PFBS advisory is based on thyroid issues in newborn mice. These advisories assume that only 20% of lifetime exposure to PFOA and PFOS will come from drinking water.
EPA’s new health advisories are not legally binding. But they signal that very low maximum contaminant levels (MCLs) may be coming for PFOA, PFOS, GenX and PFBS. The MCLs in PFOA and PFOS may be close to the lowest detectable range with current technology, at approximately 5 ppt. The EPA has stated that it expects to propose MCLs this fall.
EPA also stated that in the coming weeks it will issue a proposed rule to designate PFOA and PFOS as hazardous substances under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), which will enable EPA to leverage the full range of Superfund authorities, including requiring reporting of PFOA and PFOS releases. It will also hold polluters accountable for clean-up costs. Public water agencies have raised concerns that such a designation could subject them to potential liability for PFAS found in water or treatment biosolids.