‘Toxic Forever Chemicals’ in U.S. Drinking Water to Be Regulated for the First Time

The EPA has proposed the first nationwide limits for toxic chemicals called PFASs in the U.S. water supply

American flag with water tower in background

A water tower near the former Naval Air Station Joint Reserve Base Willow Grove in Pennsylvania. The usage of firefighting foam at nearby former military bases has been linked to tainted drinking water, affecting tens of thousands of residents in Bucks and Montgomery counties in the state.

Join Our Community of Science Lovers!

For the first time, the U.S. government has proposed limits on toxic “forever chemicals” in the nation’s drinking water.

Compounds in this class of chemicals, known scientifically as perfluoroalkyl and polyfluoroalkyl substances (PFASs), have a strong carbon-fluorine bond. That means they don’t readily break down under ambient environmental conditions—and it is suspected that they can persist in the environment for hundreds, or even thousands, of years. PFASs have been linked to a wide range of health issues, including various cancers, immune deficiencies and pregnancy complications.

Thousands of PFASs have been used in hundreds of products ranging from cookware to clothing and from firefighting foam to pesticides. The U.S. Centers for Disease Control and Prevention has found these chemicals in the blood of nearly everyone the agency has tested for them. A 2021 peer-reviewed study by the Environmental Working Group (EWG), a nonprofit advocacy organization, found that the drinking water of a majority of Americans contains at least two PFAS compounds.


On supporting science journalism

If you're enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.


A new regulatory proposal from the Environmental Protection Agency would limit the permitted drinking-water levels of six PFAS compounds: perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) individually and four others as a mixture. If finalized, the rules would require public drinking water utilities to monitor for these chemicals and to notify the public and reduce levels if they exceed certain standards. For PFOA and PFOS, this limit would be four parts per trillion (ppt). The EPA had previously advised that levels of these chemicals should not exceed 70 ppt.

“EPA’s proposal to establish a national standard for PFAS in drinking water is informed by the best available science, and would help provide states with the guidance they need to make decisions that best protect their communities,” said EPA administrator Michael Regan in a news release from the agency.

The American Chemistry Council, an industry group, announced its support for drinking water standards in its own news release. But the group took issue with the science the EPA used to set the proposed limits and warned about high compliance costs.

The proposed regulation, which will undergo a 60-day public comment period, is part of the administration’s larger PFAS Strategic Roadmap to rein in PFAS pollution.

“These six PFAS stand out as some of the most well-studied PFAS, but the entire class of chemicals is a health concern,” said David Andrews, a senior scientist at EWG, in a news release from the organization. “Action to reduce exposure cannot come soon enough.”

Andrea Thompson is senior desk editor for life science at Scientific American, covering the environment, energy and earth sciences. She has been covering these issues for nearly two decades. Prior to joining Scientific American, she was a senior writer covering climate science at Climate Central and a reporter and editor at Live Science, where she primarily covered earth science and the environment. She has moderated panels, including as part of the United Nations Sustainable Development Media Zone, and appeared in radio and television interviews on major networks. She holds a graduate degree in science, health and environmental reporting from New York University, as well as a B.S. and an M.S. in atmospheric chemistry from the Georgia Institute of Technology. Follow Thompson on Bluesky @andreatweather.bsky.social

More by Andrea Thompson

It’s Time to Stand Up for Science

If you enjoyed this article, I’d like to ask for your support. Scientific American has served as an advocate for science and industry for 180 years, and right now may be the most critical moment in that two-century history.

I’ve been a Scientific American subscriber since I was 12 years old, and it helped shape the way I look at the world. SciAm always educates and delights me, and inspires a sense of awe for our vast, beautiful universe. I hope it does that for you, too.

If you subscribe to Scientific American, you help ensure that our coverage is centered on meaningful research and discovery; that we have the resources to report on the decisions that threaten labs across the U.S.; and that we support both budding and working scientists at a time when the value of science itself too often goes unrecognized.

In return, you get essential news, captivating podcasts, brilliant infographics, can't-miss newsletters, must-watch videos, challenging games, and the science world's best writing and reporting. You can even gift someone a subscription.

There has never been a more important time for us to stand up and show why science matters. I hope you’ll support us in that mission.

Thank you,

David M. Ewalt, Editor in Chief, Scientific American

Subscribe