Perfluorooctanesulfonic Acid (PFOS)

PFOS is an eight-carbon perfluoroalkyl sulfonic acid and one of the most extensively studied legacy PFAS. It was historically used in firefighting foams, stain and water-resistant treatments, metal plating, industrial surfactants and numerous specialised applications. PFOS is exceptionally persistent and can bioaccumulate in humans and wildlife, allowing it to remain in ecosystems long after its use has stopped. Widespread environmental contamination and concerns about potential health effects have led to severe restrictions and phase-outs in many jurisdictions. PFOS is also listed under the Stockholm Convention on Persistent Organic Pollutants, making its production and use subject to international controls, with limited exemptions.