Fluorotelomer Alcohol Biodegradation Yields Poly- and Perfluorinated Acids

Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Ontario, Canada
Environmental Science and Technology (Impact Factor: 5.33). 05/2004; 38(10):2857-64. DOI: 10.1021/es0350177
Source: PubMed


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 approximately 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 beta-oxidation mechanism was furthertransformed, 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.

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    • "Zhao et al. observed that 6:2 FTUCA is a major intermediate in the biotransformation of 6:2 FTOH in marine and river sediment (Zhao et al., 2013). Dinglasen and colleagues demonstrated that 8:2 FTOH resulted primarily in 8:2 FTUCA on biodegradation in aerobic conditions with a culture obtained from sediment and groundwater (Dinglasan et al., 2004). Several metabolic studies suggest that the transformation of FTOHs into FTCAs and FTUCAs is possible by in vitro and in vivo models (Martin et al., 2005; Fasano et al., 2006). "
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    ABSTRACT: The presence of perfluorocarboxylic acids (PFCAs) in source and finished drinking waters is a concern with studies showing bioaccumulation and adverse toxicological effects in wildlife and potentially humans. Per/Polyfluoroalkyl substances (PFAS) such as fluorotelomer alcohols have been identified as precursors for PFCAs in biological pathways. In this study, we investigated the fate of 6:2 and 8:2 homologues of the fluorotelomer unsaturated carboxylic acids (FTUCAs) during advanced oxidation process (AOPs). Results showed 6:2 FTUCA and 8:2 FTUCA transformed into 6-C PFCA (PFHxA) and 8-C PFCA (PFOA) respectively with very little other PFCA formation for all AOPs. The degradation of 6:2 FTUCA and 8:2 FTUCA was greater in the GW compared to SW for the ozone processes but similar for UV/H2O2. The formation of n-C PFCA followed O3>O3/H2O2 at same dose and UV/H2O2 had much lower formation at the doses tested. Non-targeted analysis with the LC-MS-qTOF indicated the production of other PFCAs which contribute to the total mass balance, although no intermediate product was discovered indicating a rapid and direct transformation from the FTUCAs to the PFCAs and/or significant volatilization of intermediates. With the use of AOPs essential to water reuse treatment schemes, this work raises concerns over the risk of potential formation of PFCAs in the treatment and their adverse health effects in finished drinking water.
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    • "Because of the high persistence of PFOS and PFOA, contamination will remain for long periods after the substances have been emitted. In addition, mechanisms of long-range transport can transport PFAAs to locations far away from the original emission sources (Prevedouros et al., 2006; Yamashita et al., 2005; Schenker et al., 2008) and precursor compounds present in the environment can also generate PFOS and PFOA (Dinglasan et al., 2004). Some products containing PFAAs or precursors have long lifecycles prolonging environmental releases. "
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    • "An essential aspect of neutral PFAS is their conversion in ecosystems and in living organisms to more persistent PFAS, such as PFOA and PFOS. For example, 8:2 FTOH is transformed to PFOA under environmental conditions (Ellis et al., 2004; Dinglasan et al., 2004; Butt et al., 2014). Animal studies also reported that 8:2 FTOH is converted to PFOA and, to a smaller extent, PFNA after oral uptake in mice (Kudo et al., 2005; Henderson and Smith, 2007) and rats (Fasano et al., 2006; D ´ eon and Mabury, 2007; Himmelstein et al., 2012; Rand and Maybury, 2014). "
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