Environmental fate and behavior studies of a polymeric PFAS, polytetrafluoroethylene (PTFE) - results and application to risk assessment.

The term per- and polyfluoroalkyl substances (PFAS) covers a wide and diverse array of chemistry often defined as containing at least one fully fluorinated carbon. PFAS may be non-polymeric (perfluoroalkyl substances or polyfluoroalkyl substances) or polymeric (fluoropolymers, perfluoropolyethers or side-chain fluorinated polymers). Although peer-reviewed publications have demonstrated that polytetrafluoroethylene (PTFE) has low toxicity, high stability, high chemical resistance, and is not bioaccumulative, the literature does not contain environmental fate and behavior testing. This paper presents environmental fate and behavior results for a well characterized PTFE-FA (high molecular weight, fine powder, microparticulate PTFE meeting the ASTM D4895 specification). Physicochemical properties, biotic and abiotic degradation (in air, water, soil and sediment), transformation, mobility, partitioning, long range transport potential, and application of this data to the state-of-the-science polymer risk assessment are discussed. This paper asks if PTFE-FA was found in the environment, would it degrade to and subsequently release substances of concern like non-polymeric PFAS. These results demonstrate PTFE-FA's absence of mobility, degradation, adsorption to soil/sediment, partitioning to air (as a gas or vapor) from water or organic matter, long-range transport in air (as a gas or vapor), water or soil, transformation to and subsequent release of non-polymeric PFAS. Therefore, the persistence of PTFE-FA does not imply future degradation, transformation and subsequent release of substances of concern. As the EU PFAS restriction proposal evolves, this data reduces uncertainty in this fluoropolymer risk assessment based on the lack of degradation, transformation and subsequent release of substances of concern. Evaluation of environmental fate for micro- and nanoparticles and fluoropolymer end-of-life was out of scope.