Perfluorooctane sulfonic acid and its derivatives are collectively known as PFOS, they are man-made chemicals of global concern.
They break down into perfluorooctane sulfonate - a chemical that is a persistent organic pollutant (POP). Once POPs are in the environment, they are very difficult to get rid of. They can cross international boundaries by air and water currents, and bioaccumulate to toxic levels in plants and animals.
Perfluorooctane sulfonate is a fully fluorinated anion, containing a chain of eight carbon atoms. It is not a distinct substance but may be used in the form of a salt or acid. It can also be part of larger polymers. PFOS derivatives either contain perfluorooctane sulfonate within their chemical structure or can degrade to form it in the environment.
The Organisation for Economic Cooperation and Development (OECD) has produced a list of PFOS derivatives in Annex 1 of this publication:
Regulation of PFOS
In 2010, PFOS became controlled across Europe by the Persistent Organic Pollutant Regulation (EC) 850/2004 (as amended). Its production, supply and use are now banned, apart from certain limited exceptions. The Regulations also require that:
- The holder of a stockpile of PFOS-containing materials (that exceeds 50kg and is covered by an exemption) must supply details to the competent authority. We are the competent authority for England and Wales.
- Any material that contains PFOS and is not covered by an exemption must be managed as waste. It must be disposed of as soon as possible, by the methods prescribed in the EU POPs Regulation.
Perfluorochemicals are a group of substances that have been used in the past in a range of products and processes. They have previously been used in preparations that are designed to repel dirt, grease and water. As such, PFOS has historically been used in protective treatments for materials like textiles, leather, carpets, paper and board.
PFOS is now regulated as a Persistent Organic Pollutant (see above) and many of its previous uses are banned.
The EU POPs Regulation allows certain uses of PFOS to continue because assessments have shown that the environmental risks can be mitigated and do not outweigh the potential risks to human health as there are no recognised alternatives at this time.
Uses which are currently exempt from the PFOS ban are as follows:
- photoresists or anti-reflective coatings for photolithography processes
- photographic coatings applied to films, papers, or printing plates
- mist suppressants for non-decorative hard chromium (VI) plating and wetting agents for use in controlled electroplating systems where the amount of PFOS released into the environment is minimised
- hydraulic fluids for aviation
Anyone involved with a PFOS material that is covered by an exemption must make sure they manage their stocks and wastes as prescribed by the EU POPs Regulation.
PFOS in fire fighting foams
PFOS has previously been used in some fire fighting foams intended for Class B fires - those involving flammable liquids like fuel. These foams are not allowed to be produced anymore, and anyone that has a stock of them needs to comply with the law relating to phasing-out use of these foams and arrange proper disposal:
Please note: Fire fighting foams containing 6:2 fluorotelomer sulfonate (also known as H-PFOS) are not covered by the term ‘PFOS’ and are not regulated under the EU POPs Regulation.