Nearly 100million Americans are being exposed to tap water laced with chemicals linked to cancer and autism.
Researchers at the USGS — a federal agency that studies natural hazards — said a quarter of the country relies on groundwater wells that are contaminated with per- and polyfluoroalkyl substances (PFAS), also called forever chemicals.
People living in major cities like New York, Miami and Chicago were estimated to have the highest levels of PFAS in their drinking water, while those in rural areas had lower levels of the contaminant.
The researchers tested 1,200 public and domestic wells nationwide to generate a first-of-its-kind interactive map showing the worst-affected areas.
Overall, they estimated that 71 to 95million American homes.
A total of 72 percent of people relying on public wells nationwide, which supply nine in ten Americans, are thought to be drinking water contaminated with PFAS.
The study in which the results were first published warned that PFAS exposure had been linked to ‘adverse human health effects’, including thyroid problems, developmental issues and cancer.