State Key Laboratory of Urban and Regional Ecology, Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, PR China; CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization & Ecological Restoration Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, PR China.
State Key Laboratory of Urban and Regional Ecology, Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, PR China.
Ecotoxicol Environ Saf. 2018 Nov 30;164:164-171. doi: 10.1016/j.ecoenv.2018.08.007. Epub 2018 Aug 11.
Polybrominated diphenyl ethers (PBDEs) are extremely incessant anthropogenic contaminants found in the environment, with dreadful risk to aquatic ecosystems. However, there is a limited amount of data concerning their impacts on freshwater organisms. 2,2',3,3',4,4',5,5',6,6'-decabromodiphenyl ether (BDE-209) and 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) are significant components of total PBDEs in water. The sublethal effects of BDE-47, BDE-209 and their binary mixtures on the aquatic organism Daphnia magna were investigated in acute and chronic exposure experiments. Immobilization and heartbeat were studied in daphnids after 48 h of exposure. Mortality rate, breed number, Cholinesterase (ChE), Glutathione S-transferases (GST) and Catalase (CAT) activities were evaluated after 21 days of exposure. The results showed that at 100 and 200 μg/L concentration of BDE-47, immobilization rate of daphnids were inhibited by 44.0 ± 16.7% and 88.0 ± 10.9%, respectively. The binary mixture of BDE-47 and BDE-209 had uncongenial effects on immobilization of D. magna under acute toxicity test. BDE-209 significantly increased the heartbeat rate of daphnids, which increased even further when combined with BDE-47. After 21 days of exposure, daphnids exposed to single BDE-47 were physiologically altered. The combination of BDE-47 with BDE-209 significantly decreased the mortality rate of daphnids. Irrespective of the concentration, higher numbers of offsprings were produced in the mixtures compared to BDE-47 treatment alone. ChE activities significantly (p < 0.05) decreased at concentrations of 2 and 4 μg/L in single BDE-47 treatment, while GST activity significantly (p < 0.05) decreased at 0.5 μg/L. CAT activities significantly increased with BDE-47 treatments in all the tested concentrations (p < 0.05). The mixtures significantly affect ChE (p < 0.05), GST (p < 0.05) and CAT activities (p < 0.05). The results illustrated that the toxicity of the mixture of PBDE congeners exposed to aquatic organisms may have antagonistic effects. The 21 days chronic test in this study suggests that acute toxicity tests, i.e. 48-h tests, using Daphnia may lead to underestimation of risks associated with PBDEs, especially, BDE-209. Hence, there is a necessity to re-examine PBDE congeners' environmental risk in aquatic organisms.
多溴联苯醚（PBDEs）是一种在环境中普遍存在的人为污染物，对水生生态系统有严重的风险。然而，关于它们对淡水生物的影响的数据有限。2,2',3,3',4,4',5,5',6,6'-十溴联苯醚（BDE-209）和 2,2',4,4'-四溴联苯醚（BDE-47）是水中总 PBDEs 的重要成分。在急性和慢性暴露实验中，研究了 BDE-47、BDE-209 及其二元混合物对水生物溞（Daphnia magna）的亚致死效应。在暴露 48 小时后，研究了溞类的固定化和心跳。在暴露 21 天后，评估了死亡率、繁殖数、乙酰胆碱酯酶（ChE）、谷胱甘肽 S-转移酶（GST）和过氧化氢酶（CAT）活性。结果表明，在 BDE-47 的浓度为 100 和 200 μg/L 时，溞类的固定化率分别抑制了 44.0±16.7%和 88.0±10.9%。BDE-47 和 BDE-209 的二元混合物在急性毒性试验中对 D. magna 的固定化有不协同作用。BDE-209 显著增加了溞类的心跳率，与 BDE-47 结合后进一步增加。暴露 21 天后，单独暴露于 BDE-47 的溞类在生理上发生了改变。BDE-47 与 BDE-209 的组合显著降低了溞类的死亡率。与单独 BDE-47 处理相比，混合物在所有测试浓度下产生的后代数量都更高。在单独 BDE-47 处理中，ChE 活性在 2 和 4 μg/L 浓度下显著（p<0.05）降低，而 GST 活性在 0.5 μg/L 浓度下显著（p<0.05）降低。在所有测试浓度下，CAT 活性均显著（p<0.05）增加。混合物显著影响 ChE（p<0.05）、GST（p<0.05）和 CAT 活性（p<0.05）。结果表明，混合 PBDE 同系物对水生生物的毒性可能具有拮抗作用。本研究中 21 天的慢性试验表明，使用溞类进行 48 小时的急性毒性试验可能会低估 PBDEs 带来的风险，特别是 BDE-209 的风险。因此，有必要重新审查水生生物中 PBDE 同系物的环境风险。
