ABC News — Colorless and tasteless man-made chemicals, largely unregulated by the U.S. Environmental Protection Agency, has been detected in the drinking water in thousands of American communities, officials said. The chemicals referred to as PFAS, widely known as “forever chemicals” because they do not break down in the environment, have links to liver damage, high cholesterol, weakened immune systems and cancer, scientists said. “They basically fulfill the characteristics of a ticking time bomb,” said Dr. Bo Guo, a University of Arizona hydrologist and expert on per- and polyfluoroalkyl substances, which are commonly used in hundreds of consumer products and in firefighting foams, a top source of PFAS contamination. “They’re very dangerous and they’re migrating very slowly,” Guo said of the heat-resistant chemicals. Health concerns surrounding PFAS are not new, but greater detection of the chemicals in water systems nationwide has alarmed state and local leaders and prompted Congress to consider urgent action. Some level of PFAS has been found in water samples of 2,790 communities across 49 states, according to an analysis by the Environmental Working Group (EWG), an independent research and consumer watchdog organization pushing to limit exposure to chemicals through water, food, and household products. The contamination is likely to be much more widespread because the EPA doesn’t require testing for the chemicals and has not set a mandatory limit for how much PFAS are safe to drink in tap water. “It’s likely an issue in every community, and that’s why we need testing to find out,” said Sydney Evans, an EWG water quality analyst who has conducted PFAS testing across the country. In 2016, concerned by emerging health study data, the EPA issued an advisory to local water systems warning that prolonged exposure to the chemicals over 70 parts-per-trillion (ppt) may result in “adverse health effects.” The agency encouraged utilities to voluntarily monitor and filter to below that level but does not enforce a standard. During President Joe Biden’s 2020 presidential campaign, he pledged to accelerate the study and regulations PFAS. His EPA has yet to designate the class of substances as hazardous under the Safe Drinking Water Act. There is, however, growing momentum in Congress to pressure the agency over the issue. The House approved a bill that would force the EPA to establish mandatory national limits for PFAS in drinking water within two years, requiring more water systems to start filtering the chemicals out. The Senate’s pending bipartisan infrastructure bill would include billions to help communities get the job done. The chemicals have been detected on the shores of Michigan lakes, in the neighborhoods around old Naval Air Stations in Pennsylvania, and even in the groundwater of a New Mexico dairy farm whose owner alleges in federal court documents that PFAS has poisoned the cows. Analysts with EWG estimated that more than 200 million Americans could be drinking some amount of PFAS in their tap water every day. The EPA declined ABC News’ request for an interview but said in a statement that addressing PFAS in drinking water is “a top priority” and that the agency is “developing a multi-year strategy to deliver critical public health protections.”