Trade name for HFPO-DA (hexafluoropropylene oxide dimer acid), a short-chain PFAS introduced in 2009 as a replacement for PFOA in fluoropolymer manufacturing. Now regulated under the U.S. EPA's 2024 PFAS drinking water rule at 10 parts per trillion.
GenX is the commercial name for HFPO-DA, a perfluorinated ether carboxylic acid developed by DuPont and later Chemours as a processing aid for fluoropolymer production. It was introduced after PFOA was phased out under the EPA's 2010/2015 PFOA Stewardship Program, and was marketed as a safer short-chain alternative.
Field evidence has not borne out the safer claim. GenX has been detected in the Cape Fear River in North Carolina, in drinking water supplies serving roughly 250,000 people, and in air emissions from the Fayetteville Works plant. The U.S. EPA's April 2024 drinking water rule sets a Maximum Contaminant Level of 10 parts per trillion for HFPO-DA, the same threshold applied to PFNA and PFHxS.
Like long-chain PFAS, GenX is destroyed only at sustained high temperatures sufficient to break the carbon-fluorine bond. Granular activated carbon and ion exchange remove GenX from water but generate a concentrated waste stream that still requires destruction.
Also known as: HFPO-DA, hexafluoropropylene oxide dimer acid.
PFAS (Per- and Polyfluoroalkyl Substances): treatment approach
A family of thousands of synthetic fluorinated organics — including PFOA, PFOS, GenX, PFHxS, and AFFF constituents — defined by C-F bonds that resist conventional treatment and require destruction technologies to close a site.
Per- and polyfluoroalkyl substances: a class of more than 12,000 synthetic compounds built around exceptionally stable carbon-fluorine bonds. PFAS is the family name, not a single chemical. PFOA and PFOS are two specific members of this class.
Perfluorooctanoic acid: a specific eight-carbon long-chain PFAS compound, historically used in non-stick coatings and AFFF firefighting foam. Classified by IARC in 2023 as Group 1, carcinogenic to humans.
Perfluorooctane sulfonic acid: a specific eight-carbon long-chain PFAS compound, historically the active surfactant in 3M Scotchgard and AFFF firefighting foam. Classified by IARC in 2023 as Group 2B, possibly carcinogenic to humans.
Polychlorinated dibenzo-p-dioxins and related furans: highly persistent, fat-soluble chlorinated compounds formed as unintended byproducts of combustion, chlorine-based manufacturing, and herbicide production, with TCDD among the most toxic substances ever characterized.