More than 20 percent of U.S. households may rely on drinking water sources contaminated by “forever chemicals,” new research by the U.S. Geological Survey (USGS) suggests. Those in Eastern states are particularly likely to be exposed.
PFAS, which stands for per- and polyfluorinated alkyl substances, are a class of chemicals that can be found in a range of everyday products. They are nicknamed forever chemicals because they breakdown very slowly over time and stick around in their surrounding environment. As a result, PFAS can be found in soil, oceans and waterways around the world.
Now, the USGS has revealed than around 71 to 95 million Americans may rely on drinking water from groundwater supplies containing detectable levels of these PFAS. The study, published in the journal Science, is the first to report national estimates of PFAS in untreated groundwater that supplies drinking water to private and public wells. The research also provides the first estimate of the number of people who might be exposed to this contamination.
“To derive these estimates, the team analyzed 1,238 groundwater samples collected by USGS scientists and determined how factors such as urban development and well depth can impact PFAS occurrence,” Andrea Tokranov, USGS research hydrologist and lead author of this study, said in a statement.
“With that information, a detailed machine learning model was developed and used to identify which geographic areas have a higher likelihood for contamination. 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.”
The results can be seen in the map below:
Maps show probability of PFAS in groundwater before any treatment at the depths of the bottom of (A) public drinking water supplies and (B) domestic drinking water supplies.
Tokranov et al., Science/USGS
It is important to add that these concentrations are detected before the water has undergone any treatment or filtering, and concentrations of PFAS have not been measured, merely their existence. This means that while they may be present, this may be at very low levels.
For an interactive, online version of this map, visit the USGS website.
So, should we be concerned?
Numerous studies have found associations between PFAS and increased blood cholesterol and blood pressure, reduced immunity, reproductive issues and an increased risk of certain cancers, according to the U.S. Agency for Toxic Substances and Disease Registry.
However, exactly how much of a risk these chemicals pose is still unclear, and there are more than 12,000 different types, so it is difficult to say how each might affect human health. Even so, these findings indicate the importance of water monitoring and treatment in the U.S.
“This study’s findings indicate widespread PFAS contamination in groundwater that is used for public and private drinking water supplies in the U.S.,” Tokranov said.
“This new predictive model can help prioritize areas for future sampling to help ensure people aren’t unknowingly drinking contaminated water. 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.”
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References
Tokranov, A. K., Ransom, K. M., Bexfield, L. M., Lindsey, B. D., Watson, E., Dupuy, D. I., Stackelberg, P. E., Fram, M. S., Voss, S. A., Kingsbury, J. A., Jurgens, B. C., Smalling, K. L., & Bradley, P. M. (2024). Predictions of groundwater PFAS occurrence at drinking water supply depths in the United States. Science. https://doi.org/10.1126/science.ado6638
