A recent study indicates that over 20 per cent of people across the continental United States may be consuming drinking water contaminated with harmful substances known as PFAS (per- and polyfluoroalkyl substances), often referred to as "forever chemicals." This finding was published in the October 24 issue of Science Advances by the U.S. Geological Survey (USGS), revealing that between 75 to 95 million Americans depend on groundwater that contains detectable concentrations of these chemicals.
The lead investigator, Andrea Tokranov, a hydrologist with the USGS, expressed concern over the findings, stating, “This study’s results indicate widespread PFAS contamination in groundwater utilized for both public and private drinking water supplies in the United States.” Given the potential health risks associated with PFAS exposure, these findings are especially troubling.
To help the public understand their risk, the USGS has developed an interactive online map that allows people to check the likelihood of groundwater contamination in their specific areas. Tokranov explained the importance of this tool, stating, “This new predictive model can help prioritize areas for future sampling to ensure people aren’t unknowingly drinking contaminated water.” This is particularly vital for private well users who may lack information on water quality and have limited access to testing and treatment resources compared to those on public water supplies.
The study involved analysed over 1,200 groundwater samples collected by USGS scientists to detect 24 common types of PFAS. The results identified the most frequently detected compounds, including perfluorobutane sulfonate (PFBS), perfluorooctane sulfonate (PFOS), and perfluorooctanoate (PFOA). Tokranov explained that this data enabled researchers to develop a detailed machine-learning model to identify geographic areas with a higher likelihood of PFAS contamination. This model was then integrated with existing USGS research to estimate the population relying on groundwater for drinking.
Researchers identified Florida and California as the states with the highest number of people relying on public water supplies potentially drawn from contaminated groundwater. In contrast, Michigan, North Carolina, Pennsylvania, New York, and Ohio were states with significant populations relying on private wells that could also be contaminated by PFAS.
The study also provides population estimates for PFAS exposure via groundwater for each state. In Massachusetts, for instance, between 86 per cent and 98 per cent of people using public water supplies may be exposed to PFAS from contaminated sources. Meanwhile, in Connecticut, 67 per cent to 87 per cent of residents on private wells are likely consuming 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.