Su Guanyong, Letcher Robert J, Farmahin Reza, Crump Doug
Ecotoxicology and Wildlife Health Division, Environment and Climate Change Canada, National Wildlife Research Centre, Carleton University, Ottawa, ON, K1A 0H3, Canada; Jiangsu Key Laboratory of Chemical Pollution Control and Resources Reuse, School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing 210094, PR China; Department of Chemistry, Carleton University, Ottawa, ON, K1S 5B6, Canada.
Ecotoxicology and Wildlife Health Division, Environment and Climate Change Canada, National Wildlife Research Centre, Carleton University, Ottawa, ON, K1A 0H3, Canada; Department of Chemistry, Carleton University, Ottawa, ON, K1S 5B6, Canada.
Chemosphere. 2018 Mar;194:352-359. doi: 10.1016/j.chemosphere.2017.11.153. Epub 2017 Nov 30.
Tetradecabromo-1,4-diphenoxybenzene (TeDB-DiPhOBz) and 2,2',3,3',4,4',5,5',6,6'-decabromodiphenyl ether (BDE-209) are flame retardant chemicals that can undergo photolytic degradation. The present study compared the time-dependent photolyic degradation of TeDB-DiPhOBz and BDE-209, and dioxin-like product formation as a result of (UV) irradiation (I; irradiation time periods of 0, 1, 4, 15 and 40 days). Photo-degraded product fractions of UV-I-TeDB-DiPhOBz (nominal concentration: 1.9 μM) were administered to chicken embryonic hepatocytes (CEH), and significant induction of CYP1A4/5 mRNA expression was observed for fractions collected at the day 15 and 40 time points (fold change of 7.3/3.6 and 9.1/4.7, respectively). For the UV-I-BDE-209 fractions (nominal concentration: 10 μM), significant CYP1A4/5 up-regulation occurred at all time points, and the fraction collected on day 1 induced the greatest fold change of 510/86, followed by 410/68 (day 4) and 110/26 (day 15), respectively. For the UV-I-BDE-209 fraction collected at day 40, significant CEH cytotoxicity was observed. As a result, CYP1A4/5 expression was determined at a nominal concentration of 1 μM instead of 10 μM and CYP1A4/5 fold changes of 11/8.2 (day 40) were observed. Fractions eliciting the greatest CYP1A4/5 mRNA upregulation were further screened for transcriptomic effects using a PCR array comprising 27 dioxin-responsive genes. A total of 6 and 16 of the 27 target genes were up or down-regulated following UV-I-TeDB-DiPhOBz and UV-I-BDE-209 exposure, respectively. Overall, and regardless of the formation rate, these results raise concerns regarding the potential formation of dioxin-like compounds from flame retardants in products and materials such as plastics, and in natural sunlight irradiation situations in the environment (e.g. in landfill sites or electronic waste facilities).
十四溴-1,4-二苯氧基苯（TeDB-DiPhOBz）和2,2',3,3',4,4',5,5',6,6'-十溴二苯醚（BDE-209）是可发生光解降解的阻燃化学品。本研究比较了TeDB-DiPhOBz和BDE-209随时间的光解降解情况，以及紫外线（UV）照射（I；照射时间段为0、1、4、15和40天）导致的类二噁英产物形成情况。将UV-I-TeDB-DiPhOBz（标称浓度：1.9 μM）的光降解产物组分施用于鸡胚肝细胞（CEH），在第15天和第40天时间点收集的组分中观察到CYP1A4/5 mRNA表达显著诱导（倍数变化分别为7.3/3.6和9.1/（day 4）和110/26（第15天）。对于在第40天收集的UV-I-BDE-209组分，观察到显著的CEH细胞毒性。因此，在标称浓度为1 μM而非10 μM的情况下测定CYP1A4/5表达，观察到CYP1A4/5倍数变化为11/8.2（第40天）。使用包含27个二噁英响应基因的PCR阵列，对引起最大CYP1A4/5 mRNA上调的组分进一步筛选转录组效应。在UV-I-TeDB-DiPhOBz和UV-I-BDE-209暴露后，27个靶基因中分别有6个和16个上调或下调。总体而言，无论形成速率如何，这些结果引发了人们对塑料等产品和材料中的阻燃剂以及环境中的自然阳光照射情况（如垃圾填埋场或电子废物处理设施）中可能形成类二噁英化合物的担忧。
