How did PFAS chemicals once used in popular stain-resistant carpets end up in the water and environment in parts of Georgia, Alabama and South Carolina? FRONTLINE, The Associated Press, The Atlanta Journal-Constitution, The Post and Courier and AL.com investigate what happened with these forever chemicals and the ongoing health impacts. The joint investigation draws on thousands of pages of documents and court depositions and interviews with former regulators and industry insiders, as well as doctors, scientists and people who have the kinds of illnesses that researchers have linked to PFAS contamination.