While scientific studies into the impacts of PFAS in drinking water are currently limited to a handful of chemicals, the EPA and other organizations are conducting more research.
The most studied PFAS, perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS), have been identified by the EPA as contaminants of concern. Specifically, the EPA currently identifies PFOA as “likely to be a carcinogen,” which is a step below a “carcinogenic” classification. PFOS is currently identified to have “suggestive evidence of carcinogenic potential,” a step below PFOA.
The EPA recently published interim lifetime Health Advisories for PFOA and PFOS. The updated advisory levels, which are based on new science and consider lifetime exposure, indicate that some negative health effects may occur with concentrations of PFOA or PFOS in water at 0.004 parts per trillion (ppt) and 0.02 ppt, respectively. (For reference, the level at which the PFOA Health Advisory is an amount roughly equivalent to traveling 0.6 millimeters on a trip to the sun.) These interim health advisories will remain in place until EPA establishes a National Primary Drinking Water Regulation.
In March 2023, the EPA also published a proposed National Primary Drinking Water Regulation for six (6) PFAS. The proposal establishes the following maximum contaminant levels goals (MCLGs):
- A MCLC for PFOA and PFOS of 0.0 ppt is proposed, and the MCL is proposed to be 4 ppt.
- A MCLG and MCL have been proposed for PFHxS, PFNA, PFBS, and HFPO-DA using a hazard index of 1.0. A hazard index is a tool used to evaluate combined risk from exposure to a mixture of contaminants.