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The Environmental Protection Agency for the first time on Tuesday proposed enforceable regulations for “forever chemicals,” also called PFAS, in Americans’ drinking water. The six PFAS are the first new contaminants to be regulated under the Safe Drinking Water Act’s 1996 amendments.

The EPA set a threshold of 4 nanograms per liter for the chemicals PFOA and PFOS in drinking water. It also made a surprise announcement of regulations for four more PFAS together as a mixture: PFNA, GenX chemicals, PFHxS, and PFBS.

These are six of over 12,000 known “forever chemicals.” The compounds are used in products such as waterproof workout gear, burger wrappers, and cosmetics, as well as firefighting foams and the process of making nonstick coatings for pans. They have been linked to several cancers and diseases, including kidney and liver disease, Crohn’s disease, and thyroid cancer, as well as other effects like low birth rates and decreased response to vaccines.


“Communities across this country have suffered far too long from the ever-present threat of PFAS pollution,” said EPA Administrator Michael Regan in a press release. “That’s why President Biden launched a whole-of-government approach to aggressively confront these harmful chemicals, and EPA is leading the way forward.”

Thousands of other PFAS remain unregulated. However, the FDA has put the entire class of PFAS compounds under consideration for its next round of regulations around drinking water contaminants. And the EPA’s decision to include four contaminants beyond PFOA (perfluorooctanoic acid) and PFOS (perfluorooctane sulfonic acid) in its proposed regulations suggest it may adopt more class-based regulations going forward.


The agency said in a fact sheet that accompanied the announcement that the EPA decided to regulate PFNA (perfluorononanoic acid), GenX chemicals (hexafluoropropylene oxide dimer acid and its associated ammonium salt), PFHxS (perfluorohexane sulfonic acid), and PFBS (perfluorobutane sulfonic acid) together under a hazard index because recent peer-reviewed science “indicates that mixtures of PFAS can pose a health risk greater than each chemical on its own.”

In June 2022, the EPA released non-enforceable health advisory level guidelines for PFOA, PFOS, GenX chemicals, and PFBS, formalizing research that has suggested that very low exposures to PFAS can lead to adverse health outcomes. The EPA’s suggested threshold for PFOA exposure in drinking water was 0.004 ng/L; for PFOS levels, it was 0.02 ng/L. At the time, the EPA acknowledged that the 0.004 ng/L limit was so close to zero that the agency did not have a method to detect levels that low.

The standards set Tuesday account for that issue. The EPA has determined that PFOA and PFOS are likely carcinogens, meaning there is no safe level of the contaminants and their maximum contaminant level goals (MCLGs) are zero. But the EPA’s maximum contaminant levels (MCLs) — which, unlike MCLGs, are actually enforceable — are higher, in acknowledgement of the limitations of the technology necessary to measure the chemicals.

The uncertainty around how much PFAS should be allowed in drinking water due to economic and technological constraints will likely make the 60-day comment period fraught, as STAT reported late last year. “I worry about the political and cost pressures of setting something that is actually health protective,” Anna Reade, a senior scientist at the Natural Resources Defense Council, told STAT at the time. “I do think that the MCLG should be zero and the question is what the MCLs will be set at.” She hoped the MCLs would be set at 2 to 4 nanograms per liter, ranges that would be fairly protective of health but feasible for labs to measure.

The EPA’s Regan said in the press release that the agency’s strict proposals were “informed by the best available science,” which lobbying groups will undoubtedly protest. The American Chemistry Council, a chemical industry interest group, filed a petition protesting the health-based guidelines after the EPA released them last summer. “Getting the science right is of critical importance and that is why ACC has challenged these advisories based on the underlying science and the flawed process,” the ACC said in a statement to STAT last year.

The Bipartisan Infrastructure Deal passed by Congress at the end of 2021 included $9 billion to address water infrastructure impacted by PFAS and other emerging contaminants. But it will likely take much more funding and resources to address both the nation’s aging water infrastructure and contaminants like PFAS.

One challenge is that it’s expensive to install and operate the advanced treatment techniques required to remove PFAS, Chris Moody, a regulatory technical manager for the water utility society the American Water Works Association, told STAT in December. These costs mean that programs for replacing aging water mains or preventative maintenance are more likely to face budget cuts, leading to issues down the road.

“One of our main areas of concern is: ultimately, we have to find a way to fund all of this and finance it and there is some funding at the federal level, but what we’re estimating is that that’ll quickly be dwarfed by the costs of the rule, and so that’ll ultimately lead to higher water [bill] rates,” said Moody.

The proposed rule would require water utilities to begin monitoring for the six PFAS three years after the rule is finalized. The EPA proposed health-based water concentrations of 10 ng/L for PFNA, 10 ng/L for GenX chemicals, 9 ng/L for PFHxS, and 2,000 ng/L for PFBS, which would be used in the hazard index calculation to determine if the combination of chemicals exceeds their combined limit.

The EPA anticipates finalizing the rules by the end of 2023. However, the EPA has so far failed to meet promised timelines for PFAS regulation. When the EPA determined the agency would regulate PFOA and PFOS in March 2021, it projected that final numbers for the maximum contaminant levels would be announced in fall 2022. That date was pushed to the end of 2022, then an ambiguous “coming weeks” in recent press releases.

The EPA has blamed the delay on the Office of Management and Budget holding up the proposal in interagency review. The proposal finally cleared OMB on March 3, which was the Safe Drinking Water Act’s deadline for the EPA to propose the new regulations.

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