In Vivo Generation of PFOA, PFOS, and Other Compounds from Cationic and Zwitterionic Per- and Polyfluoroalkyl Substances in a Terrestrial Invertebrate (Lumbricus terrestris)

Abstract

Perfluorooctanoate (PFOA) and perfluorooctanesulfonate (PFOS) are two environmentally persistent per- and polyfluoroalkyl substances (PFAS) that have been detected globally in human tissues and fluids. As part of a project investigating the indirect sources of PFOA/PFOS in the environment and engineered systems, this study is concerned with the mechanisms leading to their in vivo generation in terrestrial invertebrates. We demonstrate here the formation of PFOA and PFOS in earthworms (Lumbricus terrestris) from a group of four zwitterionic/cationic polyfluoroalkyl amides and sulfonamides. In bioaccumulation tests, the zwitterionic PFAS compounds were metabolized within 10 days to PFOA/PFOS at yields of 3.4–20.8 mol % by day 21 and several infrequently reported PFAS species for which chemical structures were determined using high-resolution mass spectrometry. Cationic PFAS, on the other hand, were found to be much less metabolizable in terms of the number (n = 2) and yields (0.9–5.1 mol %) of metabolites. Peak-shaped bioaccumulation profiles were frequently observed for the studied PFAS. Residual zwitterionic/cationic PFAS in earthworms were detected at the end of the elimination phase, indicating that not all zwitterionic/cationic PFAS molecules in vivo are available for enzymatic degradation. Finally, the relative importance of different exposure routes (i.e., waterborne and dietary exposure) was investigated.

Thermal Decomposition of Anionic, Zwitterionic, and Cationic Polyfluoroalkyl Substances in Aqueous Film-Forming Foams

“…Our results provide further evidence that perfluoroalkyl substances (e.g., PFOA and PFOS) and certain polyfluoroalkyl substances detected at AFFF-impacted sites (soil/groundwater) may actually be transformation products of polyfluorinated compounds. Transformation of polyfluoroalkyl substances to perfluoroalkyl substances has also been observed in chemical and biological systems. ,− However, the indirect source of PFOA and PFOS has not received sufficient attention in current regulatory efforts.…”

Spatial Trends of Anionic, Zwitterionic, and Cationic PFASs at an AFFF-Impacted Site

“…For example, high concentrations of FTSs can be indicative of fluorotelomer precursor transformation (e.g., fluorotelomer thioether amido sulfonates), whereas high concentrations of perfluorinated sulfonamides can be indicative of ECF precursor transformation (e.g., perfluorooctane sulfonamide quaternary ammonium salt) . Transformation of fluorotelomer precursors in AFFF to perfluorocarboxylates has been well documented in laboratory studies ,,, and implied in field studies. , Transformation of polyfluoroalkyl sulfonamides to perfluoroalkyl sulfonates has also been demonstrated in laboratory studies ,− and inferred in field studies. , …”

Bioaccumulation of per- and polyfluoroalkyl substance in fish from an urban river: Occurrence, patterns and investigation of potential ecological drivers

“…This may also be related to efficient biotransformation, as observed in zebrafish (Shi et al, 2019). Likewise, other sulfonamide betaines also proved to be metabolized into PFAAs in earthworm (Jin et al, 2020). 5:3 FTCA may result from the aerobic or anaerobic biotransformation of fluorotelomer-based compounds (Liu et al, 2010;Chen et al, 2019).…”