State Key Laboratory of Environmental Chemistry and Ecotoxicology , Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences , Beijing 100085 , China.
College of Resources and Environment , University of Chinese Academy of Sciences , Beijing 100049 , China.
Environ Sci Technol. 2019 Jul 2;53(13):7473-7482. doi: 10.1021/acs.est.9b01514. Epub 2019 Jun 19.
Bromophenols occur naturally and are used globally as man-made additives in various industrial products. They are decomposition products of many emerging organic pollutants, such as tetrabromobisphenol A, polybrominated dibenzo- p-dioxin (PBDD), polybrominated diphenyl ethers (PBDE), and others. To characterize their biotransformation pathways, bromophenol congener 2,4,6-tribromophenol, being used most frequently in the synthesis of brominated flame retardants and having the greatest environmental abundance, was selected to hydroponically expose rice plants. After exposure for 5 days, 99.2% of 2,4,6-tribromophenol was metabolized by rice. Because of the lack of relative reference standards, an effective screening strategy was used to screen for potential metabolites that were further qualitatively identified by gas and liquid chromatography combined with high-resolution mass spectrometry. Forty transformation products were confirmed or tentatively identified at different confidence levels, including 9 phase I and 31 phase II metabolites. A large number of metabolites (39) were found in rice root, and 10 of them could be translocated and detected in rice stems or leaves. Many transformation pathways were proposed, including debromination, hydroxylation, methylation, coupling reactions, sulfation, and glycosylation. It was remarkable that a total of seven hydrophobic, persistent, and toxic OH-PBDEs and PBDD/Fs were found, indicating the biotic dimeric reactions of 2,4,6-tribromophenol that occurred in the rice plants. These results improve our understanding of the transformation and environmental fates of bromophenols, and they indicate new potential sources for OH-PBDEs and PBDD/Fs in the environment, especially in food chains.
溴酚类化合物广泛存在于自然界中，作为人工合成添加剂被应用于各种工业产品。它们也是多种新兴有机污染物（如四溴双酚 A、多溴联苯二噁英（PBDD）、多溴联苯醚（PBDE）等）的分解产物。为了研究其生物转化途径，选择在溴化阻燃剂合成中应用最广泛且环境丰度最大的溴酚同系物 2,4,6-三溴苯酚作为受试物，通过水培法对水稻进行暴露实验。在暴露 5 天后，水稻代谢了 99.2%的 2,4,6-三溴苯酚。由于缺乏相对应的参考标准，本研究采用了一种有效的筛选策略，筛选出潜在的代谢产物，并通过气相色谱、液相色谱与高分辨质谱联用技术对其进行定性分析。本研究共鉴定或推测出 40 种代谢产物，包括 9 种 I 相代谢产物和 31 种 II 相代谢产物。在水稻根中发现了大量代谢产物（39 种），其中 10 种可以在水稻茎和叶中检测到并发生迁移。本研究提出了多种转化途径，包括脱溴、羟化、甲基化、偶联反应、磺酸化和糖基化。值得注意的是，共发现 7 种疏水性、持久性和毒性的 OH-PBDEs 和 PBDD/Fs，表明 2,4,6-三溴苯酚在水稻体内发生了生物二聚反应。这些结果提高了我们对溴酚类化合物的转化和环境归趋的认识，同时也表明其可能成为环境中 OH-PBDEs 和 PBDD/Fs 的新潜在来源，特别是在食物链中。
