(CF3CF2CF2CF2CF2CF2CF2CF2SO3-) An intermediate in the production of fabric protectors that repelled water and oil, among other uses. PFOS is toxic to mammals. In 2005, Dupont decided to phase-out an analogue to this compound, perfluorooctanoic acid, by 2015 because of its widespread detection in blood of marine and Arctic animals. The 3M company is phasing-out perfluorooctane sulfonate for similar reasons. Recent data have shown that blood donors in Minneapolis-St. Paul, Minnesota have a lower blood concentration of members of this family after a 2000-2002 phase-out of perfluorooctanesulfonyl-fluoride. [Aquatic Toxicology; v82; 135-143; 2007.] [Chemosphere; v68; 105-111; 2007.]