Perfluorohexane sulphonic acid (PFHxS), its salts and related substances

  • Substance(s) name(s): Perfluorohexane sulphonic acid (PFHxS), its salts and related substances
  • CAS number(s): 355-46-4 (and other)
  • CE number(s): 206-587-1 (and other)

Classification and labelling of Perfluorohexane sulphonic acid (PFHxS), its salts and related substances

There is no harmonised classification and there are no notified hazards by manufacturers, importers or downstream users for this substance

  • Category(ies) under POPs Regulation: Industrial chemical
  • Other uses:
    • Aqueous Film-Forming Foams (AFFFs) for firefighting;
    • Metal plating;
    • Textiles, leather and upholstery;
    • Polishing agents and cleaning/washing agents;
    • Coatings, impregnation/proofing (for protection from damp, fungus etc.);
    • Within the manufacturing of electronics and semiconductors;
    • Other potential use categories may include pesticides, flame retardants, paper and packaging, in the oil industry, and hydraulic fluids;  
    • Use in certain per- and polyfluoroalkyl substances (PFASs) based consumer products;
    • PFHxS is and has been unintentionally produced during the electrochemical fluorination (ECF) processes of some other PFSAs;
    • In many applications, PFHxS has been used as a replacement for perfluorooctane sulfonic acid (PFOS).

Substance listed in Annex I, IV and V of the POP regulation with specific exemption on intermediate use or other specification.

  • Annex I presents a list of substances subject to prohibition (with specific exemptions) on manufacturing, placing on the market and use.
    • Perfluorohexane sulfonic acid (PFHxS), its salts and PFHxS-related compounds are listed in Annex I as a substance subject to prohibition (with specific exemptions) on manufacturing, placing on the market and use.
    • Certain exemptions are applicable:

1. Article 4(1), point (b), shall apply to concentrations of PFHxS or any of its salts equal to or below 0,025 mg/kg (0,0000025 % by weight) where they are present in substances, mixtures or articles.

2. Article 4(1), point (b), shall apply to the sum of concentrations of all PFHxS-related compounds equal to or below 1 mg/kg (0,0001 % by weight) where they are present in substances, mixtures or articles.

3. Article 4(1), point (b), shall apply to concentrations of PFHxS, its salts and PFHxS-related compounds equal to or below 0,1 mg/kg (0,00001 % by weight) where it is present in concentrated firefighting foam mixtures that are to be used or are used in the production of other firefighting foam mixtures. This exemption shall be reviewed and assessed by the Commission no later than 28 August 2026.’

  • Annexe IV presents a list of substances subject to waste management provisions in accordance with Article 7(4)(a): 
    • Waste containing or contaminated by Perfluorohexane sulfonic acid (PFHxS), its salts and PFHxS-related compounds can be disposed of or recovered, as long as the substance concentration in the waste remains below 1 mg/kg for PFHxS and its salts and below 40 mg/kg for the sum of PFHxS-related compounds (concentration limits specified in Annex IV).
  • In exceptional cases, Perfluorohexane sulfonic acid (PFHxS), its salts and PFHxS-related compounds present in waste, in categories listed in Annex V, Part 2, with a concentration up to   50 mg/kg for PFHxS and its salts, and up to 2000 mg/kg for PFHxS-related compounds will be dealt with in accordance with a method listed in Annex V Part 2.

Is this substance concerned by other environmental legislation? Check ECHA EU Chemicals Legislation Finder (EUCLEF) (2023)