Pursuant to the Comprehensive Environmental Response, Compensation, and Liability Act ("CERCLA" or "Superfund"), the Environmental Protection Agency (EPA) is designating two per- and polyfluoroalkyl substances (PFAS)--perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS), including their salts and structural isomers--as hazardous substances. The Agency reached this decision after evaluating the available scientific and technical information about PFOA and PFOS and determining that they may present a substantial danger to the public health or welfare or the environment when released. The Agency also determined that designation is warranted based on a totality of the circumstances analysis, including an analysis of the advantages and disadvantages of designation.