This timeline of events related to per- and polyfluoroalkyl substances (PFASs) includes events related to the discovery, development, manufacture, marketing, uses, concerns, litigation, regulation, and legislation, involving the human-made PFASs, particularly perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS). and about the companies, mainly DuPont and 3M that manufactured and marketed them. Perfluorinated compounds are a group of hundreds of human-made compounds collectively known" as PFAS. Fluorosurfactants (PFAS) have been produced and marketed by DuPont under its trademark Teflon—a fluorinated polymer. PFAS compounds and their derivatives are widely used in many products from water resistant textiles to fire-fighting foam. A replacement for PFOAs and PFOS—GenX chemic