Republished with permission from The New Lede, by Shannon Kelleher

At least 45% of US tap water is contaminated with harmful synthetic chemicals known as per- and polyfluoroalkyl substances, or PFAS, a new federal study estimates.

The study, which was conducted by the US Geological Survey (USGS), also supports previous findings that people in urban areas are more likely to be exposed to PFAS in their drinking water than those in rural places. The analysis found similar PFAS concentrations in public and private water and marks the first study to test for the chemicals in tap water from both sources across the country, the USGS said in a press release this week.

“It’s valuable to have this study, which does have at least one data point in every one of the 50 states and Puerto Rico, to attempt to measure contamination at a truly nationwide level,” said Alissa Cordner, Co-Director of the PFAS Project Lab at Northeastern University and an associate professor of sociology at Whitman College. “There’s really a need for more systematic private well testing across the country,” she added.

There are more than 12,000 types of PFAS chemicals, which are sometimes called “forever chemicals” because they do not naturally break down. PFAS have been linked to health problems including cancer, decreased fertility, and kidney disease. The chemicals have been applied to many popular consumer goods and can leach into drinking water from industrial sites, sewage treatment plants, landfills, or certain firefighting foams. A 2022 analysis found detectable levels of PFAS in about 83% of US waterways.

Concerns about widespread PFAS contamination has led to recent measures to reduce exposure to the harmful chemicals, including proposed national drinking water standards for six PFAS released by the Environmental Protection Agency (EPA) in March. At the end of June, the agency announced a new framework to prevent some new PFAS chemicals from entering the market. The chemical giants 3M, Dupont, and others recently agreed to settlements that may provide affected communities with billions of dollars to test for the toxic chemicals and remove them from their drinking water.

To investigate the extent of PFAS contamination in drinking water across the nation, a team of USGS scientists collected tap water samples from kitchen sinks at 716 locations, including protected lands, residential and rural areas with no known sources of PFAS, and urban areas and locations with PFAS-containing waste. Since many of the thousands of PFAS chemicals cannot be detected with current testing methods, the researchers tested for 32 compounds. They most frequently detected PFBS, PFHxS, and PFOA.

The authors note that their samples were analyzed by three separate laboratories that have different reporting limits. As a result, the study actually offers a conservative analysis of how much PFAS is present in US drinking water, said Cordner.

“If anything, what we see with this study is an underestimation of the scale of PFAS contamination,” she said.

“It really speaks to the need to turn off the tap of ongoing and new uses of these chemicals given how frequently we find them in drinking water,” Cordner added. “It’s very clear that as soon as these chemicals make their way into the environment, they make their way into our drinking water.”