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Perfluorooctane sulphonate (PFOS)

Perfluorooctane sulphonate belongs to a group of organic compounds, perfluorinated organic substances, which have the shared feature that all the hydrogen atoms, bound to the carbon chain, are exchanged for fluorine atoms. A reactive sulphonate group has been bound to one end of the carbon chain. Further chemical groups are bound to the sulphonate group so that various types of surface-active substances are formed. These substance may then in some cases be broken down to PFOS in nature. Altogether there are several hundred different compounds where PFOS forms part of the structure.

A large proportion of the PFOS produced forms part of polymers, where the final product may contain residues of fluorinated starting substances that have not or have only partially reacted. PFOS has been used in the past in cleaning products, in fire fighting foams and as an impregnating agent in a number of products such as carpets, furniture, paper, textiles and leather. The uses today are in metal plating industry, semiconductor industry and in hydraulic fluids for the aviation industry.

PFOS is not broken down in the environment neither chemically nor biologically. The stability shown by PFOS is typical of perfluorinated substances and is due to the carbon skeleton of which the molecule is built up. PFOS is therefore assessed as persistent in the environment, and this is confirmed by occurrences in the environment. PFOS has been found, for example, in the blood plasma of birds (white-tailed eagle, albatross) and fish. PFOS has also been encountered in high levels in polar bears and seals in the Arctic and also been detected in dolphins the Ganges and toads in the Mississippi.

In Sweden, studies on eggs from guillemots show that PFOS has been present in the Swedish environment since the 1960s and that the quantity has increased since then. Studies on fish (perch, flounder and eelpout) show that PFOS is dispersed in relatively low concentrations in lakes and along the coast throughout Sweden.

Within the Organisation for Economic Co-operation and Development (OECD), attention has been drawn to PFOS in connection with a major manufacturer, 3M, having decided to phase out its production of PFOS and PFOS-like compounds. This led to the OECD drawing up a hazard assessment of PFOS and its salts. It has also led to the United States having passed a law that stipulates that the manufacturing and importing of PFOS and 88 similar substances must be notified to the US Environmental Protection Agency (EPA) and approved.

Sweden and the UK has independently notified national regulations on marketing and use of PFOS (with the exception of hydraulic fluids). Sweden has also nominated PFOS as a candidate for the POP conventions (POP = Persistent Organic Pollutants); Stockholm Convention and CLRTAP (Convention on Long-Range Transboundary Air Pollution). The Task Force on POPs within the LRTAP convention has performed a technical review on the dossier on PFOS that has been prepared by Sweden. The conclusion was that PFOS fulfils the required criterias to be regarded as a POP.

The Scientific Committée on Health and Environmental Risks (SCHER) has in their opinion on the risk assessment prepared by the UK concluded that PFOS is very persistent, bioaccumulative and toxic, thus a PBT substance, and that PFOS also fulfils the POP criterias. Read the opinion from the committée here.

The European Parliament have approved a new EU directive (2006/122/EU) on restrictions of marketing and use of PFOS and PFOS-related substances.

Further information

Here you can read about POPs regulation.

Here you will find more information on PFOS

Occurrence and use of highly fluorinated substances and alternatives. Rapport 7/15, Swedish Chemicals Agency, 2015

Perfluorinated substances and their uses in Sweden. Report 7/06, Swedish Chemicals Agency, 2006

Hazard Assessment of Perfluorooctane Sulfonate (PFOS) and its Salts. (NV/JM/RD(2002)17/FINAL, OECD, 2002, Paris.