Perfluorooctanoic acid is needed to produce Polytetrafluoroethylene. Perfluorooctanoic acid is because it is very toxic for people and may cause cancer. The precursors for many chemical weapons are highly corrosive, their containers are therefore often treated with Polytetrafluoroethylene. For this reason, the export of Polytetrafluoroethylene from the European Union may need a special permit. 