A U.S Geological Survey study published on October 24 revealed that approximately 71 to 95 million people in the Lower 48 states may rely on groundwater containing detectable concentrations of per- and polyfluoroalkyl substances (PFAS) for their drinking water. These findings are critical for understanding the potential for PFAS contamination and guiding future studies to inform strategic planning for water resources. USGS scientists are the first to report national estimates of PFAS occurrence in untreated groundwater, which supplies water to public and private wells, providing a comprehensive overview of the number of people potentially affected by PFAS-contaminated groundwater.
The USGS also published an interactive online map showing probability estimates of PFAS occurrence in groundwater, intended for evaluation at state, regional, and national scales rather than individual household levels. The model does not include estimates of PFAS concentrations, as testing is the only way to confirm the presence of contaminants. Exposure to PFAS can lead to adverse health risks, as these synthetic chemicals do not easily break down and can build up over time in the environment, posing a concern for drinking water quality. The EPA has established legally enforceable levels for six types of PFAS in drinking water, regulating public water supplies, with some states having additional regulations for drinking water. Private well users are encouraged to seek guidance from the EPA or their state officials or water suppliers regarding treatment and testing options.
The study identified that Florida and California have the largest populations relying on public water supplies with potentially contaminated groundwater sources, while Michigan, Florida, North Carolina, Pennsylvania, New York, and Ohio have the largest populations relying on potentially contaminated groundwater from private wells. The research also presents data according to population percentage, showing that in Massachusetts and Connecticut, a significant percentage of people relying on groundwater from public water supplies or private wells could be affected by PFAS contamination. The team analyzed groundwater samples collected by USGS scientists to determine how factors like urban development and well depth can impact PFAS occurrence, developing a detailed machine learning model to identify geographic areas with a higher likelihood of contamination.
The USGS study tested for the presence of 24 common types of PFAS, with the most frequently detected compounds being PFBS, PFOS, and PFOA. With more than 12,000 types of PFAS in existence, it is crucial to continue monitoring and testing for these contaminants in drinking water sources. The research provides a broad perspective for the Lower 48 states with state-level estimates, focusing on population estimates for areas relying on public and private wells. Scientists did not investigate specific cities or provide information on the types of PFAS present or their concentrations, emphasizing the need for continued research and monitoring to ensure water safety for all.