I have received one or two queries regarding PFOS recently.
Most Perfluorooctane Sulfonate (PFOS) was originally produced in the USA by 3M. It was a key ingredient in Scotchgard, a fabric protector made by 3M, and numerous stain repellents. When 3M discovered how toxic it was they stopped making it with the result that it is now only used, via other sources, in applications where it is difficult to replace.
It was used in adhesives, paper and fabrics including coatings mainly for textiles, carpets and leather. Apparently 48 tons per year was used in the UK at one time. It was used as it provided "soil, water and oil" resistance.
Any product that provides resistance to water, dirt, oil, etc could contain PFOS - water resistant coatings, adhesives that work under water or on wet surfaces might be possibilities. There is an exemption for photolithography and so it is possibly present in photoresists.
PFOS was banned under the Marketing & Use Directive on 27/6/2008.
Directive Decoder