State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou, 510642, China; Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, 510642, China.
State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou, 510642, China; Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, 510642, China.
Environ Pollut. 2021 Mar 1;272:115908. doi: 10.1016/j.envpol.2020.115908. Epub 2020 Nov 6.
Perfluoroalkyl acids (PFAAs) are widely used in industrial production and daily life because of their unique physicochemical properties, such as their hydrophobicity, oleophobicity, surface activity, and thermal stability. Perfluorosulfonic acids (PFSAs) and perfluorocarboxylic acids (PFCAs) are the most studied PFAAs due to their global occurrence. PFAAs are environmentally persistent, toxic, and the long-chain homologs are also bioaccumulative. Exposure to PFAAs may arise directly from emission or indirectly via the environmental release and degradation of PFAA precursors. Precursors themselves or their conversion intermediates can present deleterious effects, including hepatotoxicity, reproductive toxicity, developmental toxicity, and genetic toxicity. Therefore, exposure to PFAA precursors constitutes a potential hazard for environmental contamination. In order to comprehensively evaluate the environmental fate and effects of PFAA precursors and their connection with PFSAs and PFCAs, we review environmental biodegradability studies carried out with microbial strains, activated sludge, plants, and earthworms over the past decade. In particular, we review perfluorooctyl-sulfonamide-based precursors, including perfluroooctane sulfonamide (FOSA) and its N-ethyl derivative (EtFOSA), N-ethyl perfluorooctane sulfonamido ethanol (EtFOSE), and EtFOSE-based phosphate diester (DiSAmPAP). Fluorotelomerization-based precursors are also reviewed, including fluorotelomer alcohols (FTOH), fluorotelomer sulfonates (FTSA), and a suite of their transformation products. Though limited information is currently available on zwitterionic PFAS precursors, a preliminary review of data available for 6:2 fluorotelomer sulfonamide betaine (FTAB) was also conducted. Furthermore, we update and refine the recent knowledge on biotransformation strategies with a focus on metabolic pathways and mechanisms involved in the biotransformation of PFAA precursors. The biotransformation of PFAA precursors mainly involves the cleavage of carbon-fluorine (C-F) bonds and the degradation of non-fluorinated functional groups via oxidation, dealkylation, and defluorination to form shorter-chained PFAAs. Based on the existing research, the current problems and future research directions on the biotransformation of PFAA precursors are proposed.
全氟烷基酸（PFAAs）因其独特的物理化学性质，如疏水性、疏油性、表面活性和热稳定性，被广泛应用于工业生产和日常生活中。全氟磺酸（PFSAs）和全氟羧酸（PFCAs）是研究最广泛的 PFAAs，因为它们在全球范围内存在。PFAAs 具有环境持久性、毒性，长链同系物也具有生物累积性。PFAAs 的暴露可能直接来自排放，也可能间接来自 PFAA 前体的环境释放和降解。前体本身或其转化中间体可能会产生有害影响，包括肝毒性、生殖毒性、发育毒性和遗传毒性。因此，接触 PFAA 前体构成了环境污染的潜在危害。为了全面评估 PFAA 前体的环境归宿和影响及其与 PFSAs 和 PFCAs 的关系，我们综述了过去十年中利用微生物菌株、活性污泥、植物和蚯蚓进行的环境生物降解性研究。特别是，我们综述了基于全氟辛基磺酰胺的前体，包括全氟辛烷磺酰胺（FOSA）及其 N-乙基衍生物（EtFOSA）、N-乙基全氟辛烷磺酰胺基乙醇（EtFOSE）和基于 EtFOSE 的磷酸二酯（DiSAmPAP）。还综述了氟调聚反应基前体，包括氟调聚醇（FTOH）、氟调聚磺酸盐（FTSA）及其一系列转化产物。尽管目前关于两性离子 PFAS 前体的信息有限，但我们也对现有数据进行了初步综述，这些数据来自 6:2 氟调聚磺酰胺甜菜碱（FTAB）。此外，我们更新并完善了关于 PFAA 前体生物转化策略的最新知识，重点介绍了参与 PFAA 前体生物转化的代谢途径和机制。PFAA 前体的生物转化主要涉及碳-氟（C-F）键的断裂和非氟化官能团的降解，通过氧化、脱烷基和脱氟形成较短链的 PFAAs。基于现有研究，提出了 PFAA 前体生物转化目前存在的问题和未来的研究方向。
