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Editor’s summary

Forever chemicals such as per- and polyfluoroalkyl substances (PFAS) are potential hazards for the environment and human health. The detection of PFAS in groundwater is particularly concerning, especially for drinking water sources. Tokranov et al. compiled a large database of US groundwater observations as the basis for a model to estimate the probability of PFAS contamination based on well depth. The data come from a range of well types, including those for observation, domestic tap water, and public water supply. The model highlights that about 80 million people in the conterminous US rely on groundwater with detectable amounts of PFAS before treatment. —Brent Grocholski

Abstract

Per- and polyfluoroalkyl substances (PFAS), known colloquially as “forever chemicals,” have been associated with adverse human health effects and have contaminated drinking water supplies across the United States owing to their long-term and widespread use. 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. We present an extreme gradient–boosting model for predicting the occurrence of PFAS in groundwater at the depths of drinking water supply for the conterminous United States. Our model results indicate that 71 million to 95 million people in the conterminous United States potentially rely on groundwater with detectable concentrations of PFAS for their drinking water supplies before any treatment.