The definition of perfluoroalkyl and polyfluoroalkyl substances (PFAS) continues to evolve to reflect continued study of these compounds and takes different forms depending on the regulatory body, operational criteria used, and the intended scope and application of the included list of chemicals. No universally accepted definition of perfluoroalkyl and polyfluoroalkyl substances exists. However, in general, PFAS are compounds characterized as having carbon atoms linked to each other and bonded to fluorine atoms at most or all of the available carbon bonding sites.
The PFAS Technical and Regulatory Guidance Document and Fact Sheets (PFAS-1, 2026) help state and federal environmental staff, stakeholders, project managers, decision makers, and others develop a working knowledge of the science and practices. This online resource includes a Technical and Regulatory Guidance Document, Fact Sheets, Training Resources, and Data Tables.
Topic(s): Contaminants of Emerging Concern, PFAS
