Information on the 16 chemicals added to the Stockholm Convention

Perfluorohexane sulfonic acid (PFHxS), its salts and PFHxS-related compounds

Listed under Annex A without specific exemptions (decision SC-10/13)

Risk profile Ar, Ch, En, Fr, Ru, Sp (PDF)
Risk management evaluation Ar, Ch, En, Fr, Ru, Sp (PDF)
Draft indicative list of substances covered by the listing of PFHxS, its salts and PFHxS-related compounds (UNEP/POPS/POPRC.15/INF/9)

Chemical identity and properties

“Perfluorohexane sulfonic acid (PFHxS), its salts and PFHxS related compounds” means the following:

1. Perfluorohexane sulfonic acid (CAS No. 355-46-4, PFHxS), including branched isomers;
2. Its salts;
3. Any substance that contains the chemical moiety C6F13SO2- as one of its structural elements and that potentially degrades to PFHxS.

Use and production

PFHxS, its salts and PFHxS related compounds have been intentionally used at least in the following applications: (1) Aqueous Film-Forming Foams (AFFFs) for fire-fighting; (2) metal plating; (3) textiles, leather and upholstery; (4) polishing agents and cleaning/washing agents; (5) coatings, impregnation/proofing (for protection from damp, fungus etc.); and (6) within the manufacturing of electronics and semiconductors. In addition, other potential use categories may include pesticides, flame retardants, paper and packaging, in the oil industry, and hydraulic fluids. PFHxS, its salts and PFHxS related compounds have been used 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).

POPs characteristics of PFHxS

PFHxS are very resistant to chemical, thermal and biological degradation due to their strong carbon-fluorine bonds and a resistance to degradation which makes it persistent in the environment. Numerous studies have reported elevated levels of PFHxS in soil, water and a variety of biota. Humans are exposed to PFHxS mainly through intake of food and drinking water but also through the indoor environment through dust or consumer products containing PFHxS or its precursors. Following PFOS and PFOA, PFHxS is the most frequently detected PFAS in blood-based samples from the general population worldwide. PFHxS is present in the umbilical cord blood and breast milk. Breast milk may be an important source of exposure for breast-fed infants since it is documented that PFHxS is excreted via lactation. Contamination of drinking water can result in highly increased PFHxS serum levels due to the long elimination-time in humans. Use of drinking water for food preparation can add to the background levels present in foods.

Replacement of PFHxS

The assessment of alternatives to PFOS under the Stockholm Convention has revealed that alternatives are available for all potential applications which could also be relevant for PFHxS, its salts and related compounds. Alternatives include both fluorinated and non-fluorinated substances as well as alternative (non-chemical) technical solutions. Information on availability, accessibility and price of alternatives, as well as information on regulatory measures and use in different countries, reveal that the socioeconomic costs of implementing a ban on the use of PFHxS are considered small and are outweighed by the benefits of an elimination/ regulation. High costs are estimated for remediation of contaminated sites, such as old and current fire-fighting foam training sites and airports, landfills for industrial waste, and hazardous waste, as well as for the removal of PFASs, including PFHxS, from drinking water and water sources affected by PFHxS (and other PFASs) contamination. Implementation of control measures for PFHxS, its salts and PFHxS related compounds would contribute to avoiding such future costs.

Risk profile Ar, Ch, En, Fr, Ru, Sp (PDF)
Risk management evaluation Ar, Ch, En, Fr, Ru, Sp (PDF)

Chemical identity and properties

Chlordecone is chemically related to Mirex, a pesticide listed in Annex A of the Convention.

Use and production

Chlordecone is a synthetic chlorinated organic compound, which was mainly used as an agricultural pesticide. It was first produced in 1951 and introduced commercially in 1958. Currently, no use or production of the chemical is reported.

POPs characteristics of chlordecone

Chlordecone is highly persistent in the environment, has a high potential for bioaccumulation and biomagnification and based on physico-chemical properties and modelling data, chlordecone can be transported for long distances. It is classified as a possible human carcinogen and is very toxic to aquatic organisms.

Replacement of chlordecone

Alternatives to chlordecone exist and can be implemented inexpensively. Many countries have already banned its sale and use. The main objective to phase out chlordecone would be to identify and manage obsolete stockpiles and wastes.

For more information, please refer to the alternatives to chlordecone page.