Chemical Toxicity of Per- and Poly- Fluorinated Alkyl Substances (PFAS)

Per- and poly- fluorinated alkyl substances (PFAS) include a large number of chemicals that have the general characteristic of a carbon to fluorine bond. The draft EPA method 1633 for analysis of PFAS targets 40 analytes. However, over 14,735 substances are listed as PFAS as per EPA's CompTox Chemical dashboard PFAS database. The Organization for Economic Cooperation and Development (OECD) PFAS definition is a saturated carbon-fluorine (C-F) alkyl chain (CF2), which encompasses over 6 million compounds. As of writing of this chapter, PubChem Classification browser contains more than 21 million PFAS and Fluorinated compounds There are over 400,000 known organofluorine compounds. Specific toxicities of key PFAS (other than perfluorooctane sulfonic acid; PFOS, and perfluorooctanoic acid; PFOA, both of which are discussed in other chapter entries) are summarized across the range of human and animal studies, including perfluorodecanoic acid (PFDA) as the next most studied compound behind PFOS and PFOA, Perfluorobutanesulfonic acid (PFBS), Perfluorohexanoic acid (PFHxS), and Hexafluoropropylene oxide dimer acid (HFPO-DA), the last of which is often referred to as GenX chemicals. Much attention is being paid by independent investigators and the media for this class of compounds, because of the pervasiveness, longevity, and profound toxicological effects of these compounds at very low levels.