Perfluorooctanoic acid (PFOA; CF₃(CF₂)₆COOH) is a member of the perfluoroalkyl acids (PFAA) family of chemicals, which consist of a carbon backbone typically four to fourteen carbons in length and a charged functional moiety (primarily carboxylate, sulfonate, or phosphonate). Many chemical intermediates (such as alcohols and amides) can be derived for commercial uses, but these intermediates ultimately break down to PFOA or its sister compound, perfluorooctane sulfontate (PFOS). PFAA are distinguishable from another class of perfluorocarbons, the perfluoroalkanes, primarily used clinically for oxygenation and respiratory ventilation. PFAA are relatively contemporary chemicals, in use only in the past 50 years, and until recently have been considered as biologically inactive.