Population-Wide Exposure to Per- and Polyfluoroalkyl Substances from Drinking Water in the United States

The extent of ongoing exposure to the general public from per- and polyfluoroalkyl substances (PFAS) in drinking water in the United States and worldwide remains uncertain. Here, we analyze publicly accessible data sets of PFAS occurrence in drinking water in the United States. Testing with detection limits below 1 ng/L revealed that mixtures of PFAS are nearly ubiquitous in surface water, the predominate source of drinking water for the U.S. population. We estimate that 18-80 million people in the U.S. receive tap water with 10 ng/L or greater concentration of perfluorooctanoic acid (PFOA) and perfluorooctanesulfonate (PFOS) combined, and over 200 million people likely receive water with a PFOA and PFOS concentration at or above 1 ng/L. Multiple U.S. states including California, Massachusetts, Michigan, New Hampshire, New Jersey, New York, and Vermont have either set or proposed limits for PFOA and PFOS that are significantly lower than the nonregulatory U.S. Environmental Protection Agency established lifetime drinking water health advisory level of 70 ng/L for the combined concentration of PFOA and PFOS. There is significant variation in PFAS occurrence within and between different U.S. states, highlighting the need for systematic monitoring of PFAS in both source and finished drinking water.