Implications of grouping per- and polyfluoroalkyl substances for contaminated site regulation

Per- and polyfluoroalkyl substances (PFAS) are a broad group of persistent organic compounds with vastly differing physicochemical and toxicological properties. Some jurisdictions have proposed to regulate PFAS as a single class to overcome the limitations of regulating such a diverse group on a chemical-by-chemical basis. Implications of regulating PFAS as a single class have been discussed for PFAS production and use, but equivalent discussion of implications for managing contaminated sites is largely lacking. This opinion piece summarizes the views of a group of environmental consultants, environmental regulators, land managers, and academics with significant experience in researching or managing PFAS. The group considered that neither a single PFAS class approach nor a chemical-by-chemical approach is well suited to managing risks from PFAS in a contaminated site setting, and defining PFAS subgroups would have value. Second, some but not all in the group, hypothesize that PFAS properties that drive fate and transport are those that influence toxicity and bioaccumulation in animals. This may be a valuable observation for future discussions on dividing PFAS into subclasses for contaminated site regulation based on physicochemical properties rather than purely structural definitions.