State officials knew nearly two decades ago that toxic chemicals called PFAS were spreading from the carpet mills of northwest Georgia into rivers that are the region's main source of drinking water. Local residents did not know. Now the odorless, colorless chemicals that were in their tap water are in the blood of some of them at levels higher than health guidelines consider safe. An investigation by The Associated Press, The Atlanta Journal-Constitution and FRONTLINE (PBS) has found Georgia’s Environmental Protection Division did little to confront the pollution, even as concerns grew among scientists and federal regulators about the dangers of PFAS.