Chemours’s GenX chemical, a polymer-processing aid, would become a candidate for strict regulation in the European Union under a proposal from the Dutch government. GenX is used to produce nonstick coatings and other products. It is an ammonium salt that hydrolyzes into hexafluoropropylene oxide dimer acid (HFPO-DA), which is persistent in the environment and mobile in water. The Dutch proposal says HFPO-DA “adversely impacts human health” at intake levels that could be as low as 21 ng/kg of body weight per day. Animal tests with the chemical have shown harm to the liver, kidneys, blood, and immune system. In contrast, the US Environmental Protection Agency in November proposed a safe daily level for ingestion of 80 ng/kg per day for GenX and HFPO-DA combined. After a public comment period on the Dutch proposal, the European Chemicals Agency (ECHA) will determine whether GenX, HFPO-DA, and related compounds meet criteria for “substances of very high concern” under the EU Registration, Evaluation, Authorisation, and Restriction of Chemicals law. If so, they will become candidates for phaseout in the EU, with their further use allowed only if ECHA authorizes it.