Investigation of the Biodegradation Potential of a Fluoroacrylate Polymer Product in Aerobic Soils
ABSTRACT Biodegradation of fluorinated polymers is of interest to assess them as a potential source of perfluorocarboxylates (PFCAs) in the environment. A fluoroacrylate polymer product test substance was studied in four aerobic soils over two years to assess whether the fluorotelomer alcohol (FTOH) side chains covalently bonded to the polymer backbone may be transformed to form PFCAs. The test substance itself was not directly measured; instead, nine analytes were determined to evaluate biodegradation. Terminal biotransformation products measured included perfluorooctanoate (PFO), perfluorononanoate (PFN), perfluorodecanoate (PFD), perfluoroundecanoate (PFU), and pentadecafluorodecanoate (7-3 acid). The molar concentration of 8-2 fluorotelomer alcohol (8-2 FTOH) in the test substance, fluoroacrylate polymer and residual unreacted raw materials and impurities ("residuals") were compared with the molar concentrations of the terminal biotransformation products for mass balance and kinetic assessments. Over the two year time frame of the experimental study, the fluoroacrylate polymer showed a slight extent of potential biodegradation under the experimental conditions of the study. A biodegradation half-life of 1200-1700 years was calculated for the fluoroacrylate polymer based on the rate of formation of PFO in aerobic soils. When the degradation rates of the fluoroacrylate polymer and residuals were applied to estimated total historic fluoroacrylate polymer production, use and disposal, the biodegradation of fluoroacrylate polymer and residuals is calculated to contribute less than 5 tonnes of PFO per year globally to PFCAs present in the environment.
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ABSTRACT: The aim of this study was to measure perfluoroalkyl substances in a selection of imported consumer products (n = 45) and estimate population normalized emission rates during the use phase. 6:2 and 8:2 fluorotelomer alcohol (FTOH) were found in the highest concentrations ranging from <MDL to 374 and 163 μg m−2 respectively. Concentrations of FTOHs were approximately 2–3 orders of magnitude higher than those of perfluoroalkyl carboxylic acids (PFCAs). Although perfluorooctane sulfonate (PFOS) was detected in one carpet sample at 1.7 μg m−2, the majority of samples complied with regulatory limits for PFOS in the EU. Population normalized emission rates of perfluorooctanoic acid, 6:2 FTOH and 8:2 FTOH from imported consumer products were estimated to be 6.6, 2130 and 197 μg year−1 capita−1 respectively for the “intermediate” emission scenario. The results from this study suggest that emissions from imported products would have a small impact on the environmental concentrations of perfluoroalkyl acids on a regional scale.Environmental Pollution 03/2015; 198:223-230. DOI:10.1016/j.envpol.2014.12.034 · 3.90 Impact Factor
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ABSTRACT: We identify eleven emission sources of perfluoroalkyl carboxylic acids (PFCAs) that have not been discussed in the past. These sources can be divided into three groups: [i] PFCAs released as ingredients or impurities, e.g., historical and current use of perfluorobutanoic acid (PFBA), perfluorohexanoic acid (PFHxA) and their derivatives; [ii] PFCAs formed as degradation products, e.g., atmospheric degradation of some hydrofluorocarbons (HFCs) and hydrofluoroethers (HFEs); and [iii] sources from which PFCAs are released as both impurities and degradation products, e.g., historical and current use of perfluorobutane sulfonyl fluoride (PBSF)- and perfluorohexane sulfonyl fluoride (PHxSF)-based products. Available information confirms that these sources were active in the past or are still active today, but due to a lack of information, it is not yet possible to quantify emissions from these sources. However, our review of the available information on these sources shows that some of the sources may have been significant in the past (e.g., the historical use of PFBA-, PFHxA-, PBSF- and PHxSF-based products), whereas others can be significant in the long-term (e.g., (bio)degradation of various side-chain fluorinated polymers where PFCA precursors are chemically bound to the backbone). In addition, we summarize critical knowledge and data gaps regarding these sources as a basis for future research.Environment International 05/2014; 69C:166-176. DOI:10.1016/j.envint.2014.04.006 · 5.66 Impact Factor
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ABSTRACT: Fluorotelomer alcohols [FTOHs, F(CF(2) )(n) CH(2) CH(2) OH, n = 4, 6, and 8] are emerging environmental contaminants. Biotransformation of FTOHs by mixed bacterial cultures has been reported; however, little is known about the microorganisms responsible for the biotransformation. Here we reported biotransformation of FTOHs by two well-studied Pseudomonas strains: Pseudomonas butanovora (butane oxidizer) and Pseudomonas oleovorans (octane oxidizer). Both strains could defluorinate 4:2, 6:2, and 8:2 FTOHs, with a higher degree of defluorination for 4:2 FTOH. According to the identified metabolites, P. oleovorans transformed FTOHs via two pathways I and II. The pathway I led to the production of x:2 ketone [dominant metabolite, F(CF(2) )(x) C(O)CH(3) ; x = n - 1, n = 6 or 8], x:2 sFTOH [F(CF(2) )(x) CH(OH)CH(3) ], and perfluorinated carboxylic acids (PFCAs, perfluorohexanoic, or perfluorooctanoic acid). The pathway II resulted in the formation of x:3 polyfluorinated acid [F(CF(2) )(x) CH(2) CH(2) COOH] and relatively minor shorter-chain PFCAs (perfluorobutyric or perfluorohexanoic acid). Conversely, P. butanovora transformed FTOHs by using the pathway I, leading to the production of x:2 ketone, x:2 sFTOH, and PFCAs. This is the first study to show that individual bacterium can bio-transform FTOHs via different or preferred transformation pathways to remove multiple CF(2) groups from FTOHs to form shorter-chain PFCAs. Biotechnol. Bioeng. © 2012 Wiley Periodicals, Inc.Biotechnology and Bioengineering 12/2012; 109(12). DOI:10.1002/bit.24561 · 4.16 Impact Factor