Fluorotelomer Alcohol Biodegradation Yields Poly- and Perfluorinated Acids

Abstract

The widespread detection of environmentally persistent perfluorinated acids (PFCAs) such as perfluorooctanoic acid (PFOA) and its longer chained homologues (C9>C15) in biota has instigated a need to identify potential sources. It has recently been suggested that fluorinated telomer alcohols (FTOHs) are probable precursor compounds that may undergo transformation reactions in the environment leading to the formation of these potentially toxic and bioaccumulative PFCAs. This study examined the aerobic biodegradation of the 8:2 telomer alcohol (8:2 FTOH, CF₃(CF₂)₇CH₂CH₂OH) using a mixed microbial system. The initial measured half-life of the 8:2 FTOH was ∼0.2 days mg^-1 of initial biomass protein. The degradation of the telomer alcohol was monitored using a gas chromatograph equipped with an electron capture detector (GC/ECD). Volatile metabolites were identified using gas chromatography/mass spectrometry (GC/MS), and nonvolatile metabolites were identified and quantified using liquid chromatography/tandem mass spectrometry (LC/MS/MS). Telomer acids (CF₃(CF₂)₇CH₂COOH; CF₃(CF₂)₆CFCHCOOH) and PFOA were identified as metabolites during the degradation, the unsaturated telomer acid being the predominant metabolite measured. The overall mechanism involves the oxidation of the 8:2 FTOH to the telomer acid via the transient telomer aldehyde. The telomer acid via a β-oxidation mechanism was further transformed, leading to the unsaturated acid and ultimately producing the highly stable PFOA. Telomer alcohols were demonstrated to be potential sources of PFCAs as a consequence of biotic degradation. Biological transformation may be a major degradation pathway for fluorinated telomer alcohols in aquatic systems.