Global efforts to ban the “Teflon chemical” have hit a sticking point.

PFOA, short for perfluorooctanoic acid, became famous in the 1950s when DuPont started using the stuff in its process for making non-stick frying pans. Since then, PFOA found its way into everything from GoreTex clothing to Stainmaster carpets.

PFOA also has turned up in dangerously high levels in drinking water near current and former factories, raising concerns about contamination in other parts of the country and around...