Comparative analysis of the physicochemical, toxicokinetic, and toxicological properties of ether-PFAS

Perfluoropolyethers, also known as ether-PFAS, are linear or branched alkyl ether polymers, where the substituent hydrogens on the carbon atoms in the chain have been fully replaced by fluorine atoms. Some of these molecules may have a carboxylate functional group attached to one of the terminal carbon atoms to form an ether-PFAS carboxylate. Perfluoropolyethers are used as processing aids in the manufacture of various types of perfluorinated polymeric materials which are used in a variety of consumer applications. Although the physicochemical and toxicological properties of certain perfluoropolyether compounds have been extensively studied, data are relatively sparse for some members of this class of compounds. Moreover, the physicochemical, toxicokinetic, and toxicological properties of ether-PFAS as a class have not been elucidated in previous comprehensive review articles. This article reviews the nomenclature and uses of ether-PFAS and compares the physicochemical properties, toxicokinetic characteristics, apical effects in toxicological studies, and dose-response profiles across four specific ether-PFAS compounds. This comparison, including a description of identified data gaps should help to inform the design of studies to further elucidate the characteristics of ether-PFAS and to propose potential read-across assessment strategies for members of this class.