EPA seeks to regulate 6 PFAS in drinking water nationwide

On March 14, the U.S. Environmental Protection Agency announced a new regulatory proposal to set enforceable limits on six PFAS, known as “forever chemicals,” in drinking water across the nation.

The six chemicals the EPA seeks to regulate are:
• Perfluorooctanoic acid (PFOA)
• Perfluorooctane sulfonic acid (PFOS)
• Perfluorononanoic acid (PFNA)
• Hexafluoropropylene oxide dimer acid (HFPO-DA, commonly known as GenX Chemicals)
• Perfluorohexane sulfonic acid (PFHxS)
• Perfluorobutane sulfonic acid (PFBS)

The proposed National Primary Drinking Water Regulation would mandate that public water systems monitor for these PFAS, notify the public, and reduce levels of PFAS if they exceed standards set by the EPA. The EPA expects some 66,000 water systems nationwide to be subject to the rule once it is finalized, and the agency anticipates that between 3,400 and 6,300 systems will exceed one or more of the new thresholds.

Scientific research indicates that human exposure to PFAS — short for per- and polyfluoroalkyl substances — may lead to adverse health outcomes such as reproductive effects, developmental effects in children, increased cancer risk, and interference with the body’s immune and hormonal systems.

EPA proposal details
The EPA’s proposal would establish legally enforceable levels, or maximum contaminant levels (MCLs), of 4 parts per trillion (ppt) for PFOA and 4 ppt for PFOS.

The four other PFAS chemicals would be regulated as a mixture of chemicals through a hazard index (HI), a tool often used in the Superfund program to evaluate health risks from chemical mixtures. Water systems would use the proposed hazard index calculation to determine whether action is required to mitigate PFNA, GenX Chemicals, PFHxS, and PFBS. Under the proposal, a running annual average hazard index value greater than 1.0 would be a violation of the proposed HI MCL.

Once finalized, water systems will have three years to reach compliance with the new regulatory requirements.

In addition to the enforceable maximum contaminant levels, the proposal includes health-based maximum contaminant level goals, or MCLGs, which are not legally enforceable. This measure represents the margin of safe exposure — the maximum level of exposure where there is no known negative effect on an individual’s health.

The MCLGs proposed for PFOA and PFOS are both 0 ppt, meaning there is no safe level of exposure to these two chemicals. The accompanying MCLG for PFNA, GenX Chemicals, PFHxS, and PFBS is a combined 1.0 hazard index value.

Existing regulatory landscape
In 2016, the EPA established health advisories for PFOA and PFOS indicating that PFOA and PFOS in drinking water at a combined concentration of more than 70 ppt could result in adverse health effects. Health advisories are unenforceable and nonregulatory, but they help to educate water systems and their customers about health risks.

In 2020, Massachusetts established drinking water standards requiring public water suppliers to test for a set of six PFAS compounds, called PFAS6, and to take remedial actions when amounts exceeded 20 ppt — much lower than the EPA’s health advisory at the time.

In June of 2022, the EPA released interim updated health advisories for four PFAS chemicals, including PFOA and PFOS, replacing the advisories from 2016. The 2022 advisories revealed that some negative health effects may occur with concentrations of certain PFAS in water that are near zero.

The Massachusetts PFAS6 includes PFOA, PFOS, PFHxS, PFNA, perfluoroheptanoic acid (PFHpA) and perfluorodecanoic acid (PFDA). The EPA’s new proposal addresses PFOS, PFOA, PFHxS and PFNA, but not PFHpA and PFDA.

The Massachusetts Department of Environmental Protection said it plans to pursue PFAS water regulations that are at least as stringent as the federal standards. The MassDEP website has more information on its PFAS efforts.

Following the work of the PFAS Interagency Task Force over the past few years, the group’s chairs, Rep. Kate Hogan and Sen. Julian Cyr, filed an omnibus bill (H. 2197 and S. 1356) in January to implement many of the task force’s recommendations, including the creation of a PFAS Remediation Trust Fund. The bills have been assigned to the Joint Committee on Public Health for review.

Next steps
The EPA is requesting public comment on its proposed drinking water regulations through www.regulations.gov, under Docket ID: EPA-HQ-OW-2022-0114. The proposal was published in the Federal Register on March 29, and comments must be submitted by May 30.

The EPA will hold a public hearing on May 4 from 11 a.m. to 7 p.m. Registration is required by April 28.

The EPA website has more detailed information, including links to webinar recordings and materials, summaries of the federal water regulation changes, and technical materials.

The EPA anticipates finalizing its PFAS regulations by the end of this year.