PFHxA (Undecafluorohexanoic Acid) Restriction

Undecafluorohexanoic acid (PFHxA, CAS No. 307-24-4) is a short-chain (C6) perfluorocarboxylic acid. PFHxA and its salts and related substances face restriction under EU REACH Annex XVII, with the restriction entering into force in April 2026. This restriction was proposed by German authorities in 2019 and adopted by the European Commission. It covers PFHxA, its salts, and precursors that can degrade to PFHxA in the environment.

REACH Annex XVII (PFHxA restriction); ECHA RAC/SEAC Opinions (2021); European Commission Delegated Regulation.

The PFHxA restriction is significant because it targets short-chain PFAS that industry widely adopted as replacements for long-chain PFAS like PFOA. Companies that reformulated products using C6 fluorochemistry now face a second round of reformulation. The restriction applies to placing on the market of PFHxA-containing substances, mixtures, and articles above specified concentration limits. Transition periods vary by application sector.

A textile finishing company in Germany switched from C8 (PFOA-based) water-repellent treatments to C6 (PFHxA-related) treatments in 2012. With the PFHxA restriction entering force in April 2026, the company must now transition to fluorine-free alternatives or confirm that its specific C6 products fall within a sector-specific derogation.