Abstract
Recent publications have highlighted the ubiquitous presence of unidentified organofluorine compounds, whose environmental occurrence is poorly understood. In this study, wastewater treatment plant (WWTP) effluent and sludge samples from seven countries were analyzed for extractable organofluorine (EOF) and target PFAS, to evaluate which compounds are released back into the environment. Fluorine mass balance analysis of effluent samples (n = 14) revealed that on average 90% of the EOF could not be explained by the 73 PFAS monitored in this investigation. The levels of EOF in effluent (324–1460 ng of F/L) and sludge (39–210 ng of F/g of dry weight) indicate that a substantial amount of organofluorine compounds is released back into nature. A commonly overlooked PFAS class, ultra-short-chain PFCAs, accounted for 4% of EOF on average, while the remaining 71 compounds explained only a further 6% of EOF on average. The highest number of PFAS was detected in the effluent dissolved phase (37), compared to 29 and 23 PFAS in sludge and effluent particulate phase, respectively. The increased concentrations of EOF in both WWTP effluent and sludge are of concern, as the chemical species contained therein remain largely unknown, and thus, their potential health and environmental risks cannot be assessed.
Highlights
Per- and polyfluoroalkyl substances (PFAS) make up a group of anthropogenic compounds containing the perfluoroalkyl moiety CnF2n+1−
The levels of extractable organofluorine (EOF) were measured in wastewater treatment plant (WWTP) effluent (n = 14) and sludge (n = 12), of which all but two sludge samples showed quantifiable levels above the limit of quantification (LOQ)
Despite increasing the number of analytes, beyond what has been recently measured in WWTP effluent,[16,38] the 73 compounds monitored here accounted for only 10% of the EOF on average
Summary
Per- and polyfluoroalkyl substances (PFAS) make up a group of anthropogenic compounds containing the perfluoroalkyl moiety CnF2n+1−. 5000 PFAS are commercially available as of 2018,1 excluding production intermediates, impurities, and degradation products.[2] Due to their unique properties, PFAS have a wide range of uses from additives in cosmetics to mist suppressants used in metal plating[3,4] and are persistent in the environment, leading to their ubiquitous occurrence. While the production of perfluorooctanesulfonic acid (PFOS) has been limited since 2000,5 due to it displaying detrimental effects on living organisms (e.g., neurotoxicity and hepatotoxicity6,7), production has shifted to alternative PFAS, for example, short-chain PFAS8 and ether compounds.[4] In addition to well-studied compounds like PFOS and perfluorooctanoic acid (PFOA), recent studies have reported the presence of several new substitute products in the environment (from China[9] and North America10) and in humans (from Germany[11]). Information regarding the levels in the environment is scarce for most PFAS
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