MONDAY, Oct. 28, 2024 (HealthDay News) -- More than 20% of people in the continental United States might have drinking water contaminated with “forever chemicals,” a new study suggests.

Between 75 and 95 million Americans rely on groundwater that contains detectible concentrations of these chemicals, known as PFAS (per- and polyfluoroalkyl substances), the U.S. Geological Survey (USGS) estimated in the Oct. 24 issue of the journal Science Advances.

“This study’s findings indicate widespread PFAS contamination in groundwater that is used for public and private drinking water supplies in the U.S.,” said lead investigator Andrea Tokranov, a USGS research hydrologist.

Based on its study, the USGS created an interactive online map people can use to check the probability that groundwater in their area is contaminated with PFAS.

“This new predictive model can help prioritize areas for future sampling to help ensure people aren’t unknowingly drinking contaminated water,” Tokranov said in a USGS news release. “This is especially important for private well users, who may not have information on water quality in their region and may not have the same access to testing and treatment that public water suppliers do.”

For the study, researchers tested more than 1,200 groundwater samples collected by USGS scientists for the presence of 24 common types of PFAS. 

The most frequently detected compounds were perfluorobutane sulfonate (PFBS), perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA), results showed.

“With that information, a detailed machine-learning model was developed and used to identify which geographic areas have a higher likelihood for contamination,” Tokranov said. “That information was combined with existing USGS research on the number of people in a given area who rely on groundwater for drinking water to establish population estimates.”

Florida and California are the states with the most people relying on public water supplies drawn from potentially contaminated groundwater sources, researchers say.

Michigan, Florida, North Carolina, Pennsylvania, New York and Ohio have the most people whose private wells could be contaminated by PFAS, results show.

The study also includes population estimates of PFAS exposure from groundwater for each state.

For example, 86% to 98% of people in Massachusetts on a public water supply could be exposed to PFAS from contaminated groundwater, while 67% to 87% of Connecticut residents on private wells likely have PFAS-contaminated drinking water.

PFAS are called “forever chemicals” because they combine carbon and fluorine molecules, one of the strongest chemical bonds possible. This makes PFAS removal and breakdown very difficult.

PFAS compounds have been used in consumer products since the 1940s, including fire extinguishing foam, nonstick cookware and food wrappers, researchers said. The chemicals are also widely used in industrial processes.

Health concerns linked to PFAS include lowered immune response to vaccination, impaired liver function, decreased birth weight and increased risk of some cancers.

The U.S. Environmental Protection Agency has set maximum contamination levels for six types of PFAS in drinking water, the researchers noted.

More information

The U.S. Environmental Protection Agency has more about PFAS.

SOURCE: U.S. Geological Survey, news release, Oct. 24, 2024