In recent weeks, the leadership of the U.S. Environmental Protection Agency (EPA) in Washington, D.C., has been dithering on whether to protect drinking water from unregulated industrial chemicals known as per- and polyfluoroalkyl substances (PFAS). Meanwhile, the agency’s scientists have found that the compounds are more widespread in drinking water than they previously knew.
PFAS chemicals are widely used to make nonstick and water-proof products, including foams used to fight fires. Two of the most common forms—perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS)—are no longer made in the United States, but in some cases have been replaced by related chemicals. The compounds can persist in the environment for decades and have been found in many drinking water supplies. That has raised health concerns because studies have linked PFAS to cancer and developmental defects.
EPA is facing pressure to set a national limit on PFAS concentrations in drinking water. (Some states have already set their own limits.) But the agency has not yet acted, and has disputed reports that it will not issue a standard. In the meantime, many communities have been pushing officials to test water supplies in order to document the extent of any contamination.
A study quietly released earlier this month by scientists at EPA and the United States Geological Survey suggests the chemicals are widespread. They found some combination of 14 PFAS compounds in all 50 drinking water samples they tested, a dramatic jump from a similar 2016 study that used less sensitive testing methods and found the chemicals in less than 3% of samples.
The researchers took two samples at 25 water treatment plants; one of water before it had been treated, and the other after treatment. Just one sample contained PFOA concentrations above 70 nanograms per liter (ng/l), the level EPA currently considers an “advisory” threshold, they report in Science of the Total Environment. (That EPA level is far too high, the Centers for Disease Control and Prevention in Atlanta concluded in a study.) The researchers also measured concentrations of three other PFAS compounds that exceeded 70 ng/l, but the government has set no advisory standards for these compounds.
The study helps highlight “how widespread PFAS are in the environment,” says Jamie DeWitt, an environmental toxicologist at East Carolina University in Greenville, North Carolina, who was not involved in the work. And it suggests that “PFOA and PFOS are not the only PFAS that we should be concerned about.”
The study does not indicate how many people might be drinking the tested water, because the sampling locations are confidential. But using 2016 data collected by federal scientists, the Environmental Working Group (EWG), an advocacy group based in Washington, D.C., estimates that up to 110 million people are served by water supplies with PFAS.
Olga Naidenko, EWG’s senior science adviser, notes that it is unusual for researchers to detect PFAS chemicals in drinking water above the EPA advisory level. And she believes the agency’s existing advisory levels for PFOS and PFOA “are not sufficiently protective.” Communities with high concentrations, she says, should be informed.
The stakes surrounding studies of PFAS prevalence, concentrations, and human health impacts are immense. Stricter standards could force U.S. drinking water suppliers to spend hundreds of billions of dollars to remove the chemicals. And they could require those who used the chemicals—including industrial facilities, fire fighters, and the U.S. military—to pay for cleanups and potentially even damages for people who can show their health was harmed by the substances.