Production Mechanism of Hydroxylated PCBs by Oxidative Degradation of Selected PCBs Using TiO2 in Water and Estrogenic Activity of Their Intermediates
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- 作者：Kei Nomiyama ; Teiji Tanizaki ; Hiroshi Ishibashi ; Koji Arizono ; and Ryota Shinohara
- 刊名：Environmental Science & Technology
- 出版年：2005
- 出版时间：November 15, 2005
- 年：2005
- 卷：39
- 期：22
- 页码：8762 - 8769
- 全文大小：240K
- 年卷期：v.39,no.22(November 15, 2005)
- ISSN：1520-5851
文摘
The oxidative photodegradation behaviors of selectedpolychlorinated biphenyls (PCBs) [2,3,3',4'-tetraCB (BZnumber: CB56), 2,3',4',5-tetraCB (CB70), and 3,4,4',5-tetraCB(CB81: coplanar PCB)] using titanium dioxide (TiO2) inwater were investigated. The main purposes were to clarifythe structural relation between the original PCBs andthe intermediates derived by TiO2 oxidation and to evaluatethe estrogenic activity in the treated PCBs during theoxidative reactions. Approximately 90% of the three tetraCBsdecomposed within 120 min. Intermediates by decompositionof three tetraCBs, such as some OH-tetraCBs and OH-triCBs, carboxylic intermediates, phenolic intermediates,and other intermediates produced by the cleavage ofa benzene ring were identified and quantified. In thedegradation pathways, the produced amounts of OH-tetraCB and OH-triCB increased within 60 min of irradiationtime. Estrogenic activities of the intermediates from thethree tetraCBs in water were assessed by using a yeast two-hybrid assay system for human estrogen receptor 
(hER). The maximal estrogenic activities were inducedby the solutions of decomposed CB81 with irradiation timeat 60 min. We found that the solutions at an irradiationtime of 60-120 min contained several 4-OH-tetraCBs and4-OH-triCBs substituted with OH and Cl at para- and para'-positions. It is presumed that the chemical structures of the4-OH-PCBs are similar to that of 17
-estradiol (-E2);these intermediates present strong estrogenic activities.Moreover, we learned that there is a high possibilityof conversion from some low toxic PCBs congeners tostrong estrogenic OH-PCBs.
(hER). The maximal estrogenic activities were inducedby the solutions of decomposed CB81 with irradiation timeat 60 min. We found that the solutions at an irradiationtime of 60-120 min contained several 4-OH-tetraCBs and4-OH-triCBs substituted with OH and Cl at para- and para'-positions. It is presumed that the chemical structures of the4-OH-PCBs are similar to that of 17-estradiol (-E2);these intermediates present strong estrogenic activities.Moreover, we learned that there is a high possibilityof conversion from some low toxic PCBs congeners tostrong estrogenic OH-PCBs.