Cancer-Linked PFAS Are in Up to 95 Million Americans’ Tap Water

At least 20% of the population in the US relies on drinking water that has been contaminated with PFAS, according to a US Geological Survey study published Thursday.

The untreated water supply for as many as 95 million people in the contiguous US uses drinking water that has detectable levels of per- and polyfluoroalkyl substances (PFAS), which have been linked to cancer and other diseases, according to the research published in the journal Science.

The scientists used a predictive model to estimate the total number of people affected by PFAS-contaminated water—the first research showing national estimates of PFAS levels in untreated groundwater.

PFAS are likely to spread in regional groundwater as aquifers recharge and chemicals migrate into deeper aquifers, the study concludes.

“People in the United States may unknowingly be drinking water that contains PFAS because of a lack of systematic analysis, particularly in domestic water supplies,” the study says.

The states with the most residents reliant on public water systems that use PFAS-contaminated water supplies are Florida and California. States with the most residents reliant on private wells likely to be contaminated with PFAS include Michigan, Florida, North Carolina, Pennsylvania, New York, and Ohio.

The Environmental Protection Agency set the country’s first drinking water standards for six types of PFAS in April after determining that almost no level of exposure to the substances is safe.

“This new predictive model can help prioritize areas for future sampling to help ensure people aren’t unknowingly drinking contaminated water,” Andrea Tokranov, USGS research hydrologist and the study’s lead author, said in a statement. “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.”

The EPA’s new standards include an enforceable 4 parts per trillion limit on perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) in drinking water. The agency set a non-enforceable maximum contaminant level goal for PFOA and PFOS at zero.

The model the USGS researchers used does not estimate PFAS concentrations in drinking water, and it does not factor in any water utility efforts to remove the PFAS from drinking water.

The researchers analyzed 1,238 groundwater samples and tested for 24 different PFAS to determine how urban development and water well depth affect the presence of those chemicals in well water.