Occurrence and Fate of Fluoroalkyl Sulfonamide-Based Copolymers in Earthworms-Bioavailability, Transformation, and Potential Impact of Sludge Application.

ABSTRACT

To date, considerable knowledge and data gaps regarding the occurrence, environmental levels, and fate of polymeric perfluoroalkyl and polyfluoroalkyl substances (PFAS) exist. In the present study availability, accumulation, and transformation of C4- and C8-fluoroalkylsulfonamide (FASA)-based copolymers were assessed in laboratory-grown earthworms (Eisenia fetida, triplicate of exposure tests and control). Further, a field study on earthworms (18 pooled samples) in sludge-amended soil was conducted to assess the environmental impact of sludge-amended soil with regard to the FASA-based copolymers, together with the applied sludge (n = 3), and the field soils during the period (n = 4). In the laboratory study, the FASA-based copolymers were taken up by the earthworms in concentrations between 19 and 33 ng/g of dw for the C8- and between 767 and 1735 ng/g of dw for the C4-FASA-based copolymer. Higher biota soil accumulation factors (BAFs) were observed for the copolymer with a longer perfluorinated side-chain length (C8, average BAF value of 0.7) compared to the copolymer with a shorter side-chain length (C4, average BAF value of 0.02). Perfluorooctane sulfonamidoacetates (FOSAAs) and perfluorooctane sulfonamide (FOSA), including both branched and linear isomers, were detected after exposure to the C8-FASA-based copolymer. Two metabolites were detected in the earthworms exposed to the C4-FASA-based copolymer perfluorobutanesulfonamide (FBSA) and perfluorobutanesulfonic acid (PFBS). Although the presence of other monomers or impurities in the copolymer formulation cannot be ruled out, the present laboratory study suggests that the FASA-based copolymers may be an indirect source of lower molecular weight PFAS in the environment through transformation. Elevated levels of C8-FASA-based copolymer were found in the field sludge-amended soil compared to nontreated soil (32 versus 11 ng/g d.w.), and higher concentrations of PFAS in earthworms living in sludge-amended soil compared to nontreated soil (566 versus 103 ng/g d.w.) were observed. These findings imply that the application of sludge is a potential pathway of PFAS to the environment.