On October 25, 2021, the US Environmental Protection Agency (EPA) released its final human health toxicity assessment for two substances known as “GenX chemicals.” The assessment determined a reference dose for hexafluoropropylene oxide (HFPO) dimer acid (CAS 13252-13-6) and its ammonium salt (CAS 62037-80-3) of 3 ng/kg body weight/day. This is notably lower than the value of 80 ng/kg body weight/day for the same chemicals as determined in the EPA’s earlier draft assessment in 2018 (FPF reported). It is also lower than the exposure limit of 20 ng/kg body weight/day that the agency currently has set for perfluorooctanoic acid (PFOA; CAS 335-67-1), which is the hazardous substance GenX chemicals were specifically developed as a “sustainable substitute” for. The EPA writes in its report and fact sheet that it is “currently reevaluating toxicity information for PFOA and PFOS” and that the currently set reference doses for them are likely to change.

GenX is used as a processing aid for fluoropolymer production. It is also a food contact chemical present in the Food Packaging Forum’s Food Contact Chemicals database (FCCdb) indicating its intentional use in the manufacture of food contact materials. GenX rose to a level of international concern when it was discovered that a Chemours manufacturing plant in the US state of North Carolina had been releasing the substance into a river thereby contaminating a primary drinking water source for hundreds of thousands of residents downstream. Litigation regarding that contamination is still ongoing. In 2019, the chemicals were officially recognized in the EU as substances of very high concern (SVHCs) as having probable serious effects on human health and the environment (FPF reported).



US EPA (October 2021). “Human Health Toxicity Assessments for GenX Chemicals.”

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Cheryl Hogue (October 25, 2021). “US EPA deems two GenX PFAS chemicals more toxic than PFOA.” Chemical and Engineering News