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‘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.

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.


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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 an associate editor covering the environment, energy and earth sciences. She has been covering these issues for 16 years. 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.

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