PFOS

PFOS, perfluorooctane sulfonate (C8F17SO3-), is one of the most-studied PFAS and a regulated persistent organic pollutant. It was a key ingredient in aqueous film-forming firefighting foams and stain repellents, reaching the marine environment through firefighting runoff and wastewater. The Conference of the Parties listed PFOS, its salts, and PFOSF in Annex B of the Stockholm Convention in 2009 (decision SC-4/17), and the 2019 review removed most acceptable purposes (SC-9/4). It is persistent, protein-binding, and bioaccumulative, concentrating in the blood and liver of fish, seabirds, and marine mammals.