Perfluorooctane Sulfonic Acid
What is Perfluorooctane Sulfonic Acid (PFOS)?
PFOS belongs to the group of the perfluorinated surfactant, and is a subgroup of the per- and polyfluorinated alkyl compounds (PFAS). PFOS can be released into the environment through their production and usage, but they can also be formed by degradation of fluortelomeres. As it can be transported over long ranges, PFOS can even be found in the Arctic and Antarctic.
PFOS and PFOA
Both PFOS and PFOA (Perfluorooctanoic acid) are industrial chemicals, which have been used in a wide variety of products, for example as surface treatment agents in textiles (e.g. outdoor clothing) and papers (e.g. baking paper), as impregnating agents, in ski waxes or in fire fighting foams.
Properties
PFOS is a surfactant, meaning that it can lower the surface tension of a liquid or interfacial tensions between two phases, which means that it enables/supports formation of dispersions. Thus, it functions as a solubiliser.
Usage and applications
Because of the mentioned surface-active properties, meaning its resistance/repellency to oil, water, grease or soil, PFOS was mostly used as an impregnation for paper or textiles. It was an essential component of the surface- and fibre preservative ScotchgardTM manufactured by the company 3M, but it can also be found in electric and electronic parts, as coatings used in analogue photography or as hydraulic fluids, cleaning agents, varnishes or coatings in aviation and aerospace.
Some examples of applications:
- Firefighting foams
- Carpets
- Leather and clothes
- Textiles and upholstery
- Paper and packaging
- Coatings and coating additives
- Industrial and household cleaning products
- Pesticides and insecticides
- Hydraulic liquid for aerospace
Risks
PFOS is persistent and bioaccumulative, and enriches itself in the food chain. PFOS affects the liver, kidney, thyroid and reproduction system, leading to cancer formation. It can have long term effects to the aquatic life.
Laws and regulations
In 2001, the biggest producer of PFOS, the company 3M, voluntarily ceased to use PFOS because of its toxic properties. At the end of 2006, the introduction and use of PFOS was banned in the EU. However, the use of PFOS in photography, electroplating and as hydraulic is still acceptable. PFOS belongs to the group of persistent organic pollutants (POPs). In May 2009 PFOS and its salts were listed in the Stockholm Convention. The production and use of PFOS is regulated in Annex B of the Convention. There are applications, which – with certain requirements of course – are still acceptable or should be replaced with an alternative until a specified deadline.