We know where a lot of it came from. Emphasis because it's an historical problem: Military and civil air fire-fighting foam. About a million tons of perfluoro

We know where a lot of it came from. Emphasis because it's an historical problem: Military and civil air fire-fighting foam. About a million tons of perfluoroalkyl was put into the environment between 1970 and 2000. It's very mobile, so it quickly got into groundwater and rivers. By comparison the leach from Teflon pans is probably a small percentage.