Selected Fluoropolymers (A Class of PFAS Polymers)

Abstract

This chapter is about a series of fluorinated polymers (fluoropolymers) which belong to a broad class of chemical substances referred to as per‐ and polyfluoroalkyl substances (PFAS). PFAS are a unique class of anthropogenic chemicals consisting of carbon and fluorine atoms joined by very strong bonds, resulting in high‐performance properties. The overall structure of these fluoropolymers is the covalent linkage of one or more monomers, at least one of which is generally short carbon chains with fluorine atoms substituting for hydrogen atoms. The resulting fluoropolymer is a much larger molecule with very different uses, kinetics, and potential toxicity than the constituent monomers. For example, fluoropolymers are generally not well‐absorbed, if at all, in biological systems, thus avoiding to a great degree of any untoward toxicity. Unlike the monomers, the resulting fluoropolymers are usually chemically stable, biologically inert and nonbioaccumulative, water and oil resistant, and useful for many industrial applications. Because the chemical structure of these fluoropolymers makes them generally biologically unreactive and chemically inert, the available epidemiology and toxicology literature is minimal. This chapter will review the literature on fluoropolymers but will also briefly discuss the toxicity of the constituent monomers. Afterward, a summary of estimates of potential human risk by various agencies will be described. For information and practical guidance on the use of terminology in regard to PFASs, readers are referred to the OECD PFAS Terminology report [OECD, Reconciling Terminology of the Universe of Per‐ and Polyfluoroalkyl Substances: Recommendations and Practical Guidance , OECD Series on Risk Management, No. 61, OECD Publishing, Paris, 2021. Available at https://www.oecd.org/chemicalsafety/portal‐perfluorinated‐chemicals/terminology‐per‐and‐polyfluoroalkyl‐substances.pdf . Accessed October 10, 2023).