A new report says man-made "forever chemicals" are more commonin U.S. drinking water supplies than earlier estimates suggested.An environmental group reported Wednesday that some of the highest levels were measured in three big cities.They are Miami, Florida; Philadelphia, Pennsylvania; and New Orleans, Louisiana."Forever chemicals," known as PFAS, resist breaking down in the environment.They have possible links to cancer, liver damage and other health problems.The findings of the Environmental Working Group, or EWG, show its 2018 estimate could be far too low.That estimate suggested that 110 million Americans could be contaminated with PFAS."It's nearly impossible to avoid contaminated drinking water from these chemicals,"said David Andrews, a scientist with the Environmental Working Group.He helped prepare the new report.The chemicals were used in products like Teflon and Scotchguard.Their replacements also could prove harmful to human health.The EWG studied tap water from 44 areas in 31 states and Washington, D.C.Tap water is a term for water from the public water system.Of the 44 water samples, only one area had no measurable levels of PFAS.That community was Meridian, Mississippi,which gets its drinking water from wells that are 215 meters underground.Only Seattle, Washington and Tuscaloosa, Alabamahad levels below 1 part per trillion, the limit the EWG suggests.EWG found an average of six to seven different PFAS chemical compounds at the tested sites.The effect of these mixtures on human health is unclear.But Andrews used negative language to describe the chemicals."Everyone's really exposed to a toxic soup of these PFAS chemicals," he said.The United States Environmental Protection Agency, or EPA,has known since at least 2001 about the problem of PFAS in drinking water.But the agency has yet to set a national legal limit.EPA officials said early last year they would begin the processof setting limits on two of the chemicals, PFOA and PFOS.The EPA said it has helped state governments deal with PFASand that it is working to set limits on the two main chemicals.But the timing for such limits remains unclear.