Key Laboratory of Pollution Process and Environmental Criteria Ministry of Education, College of Environmental Science and Engineering, Nankai University, Tianjin 300071, China.
Environ Sci Pollut Res Int. 2013 Feb;20(2):957-66. doi: 10.1007/s11356-012-1264-7. Epub 2012 Nov 28.
Aquatic ecosystems are vulnerable to the exposure with petrochemicals such as toluene, ethylbenzene, and xylene (o-, m-, and p-xylene) (TEX) and their adverse effects. Considering the widespread use, occurrence, and high toxicity of TEX, the aim of this work was to investigate the differential toxicity of TEX against midge (Chironomus plumosus) larvae and reveal the joint action of binary and ternary mixtures of TEX using the predictive concentration addition model. More importantly, this research can afford the basic toxicity data and scientific reference for the establishment of water quality criteria or benchmark, water pollution control, and aquatic risk assessment. Single and joint toxic effects of TEX on C. plumosus larvae were investigated using a semi-static bioassay, and the type of joint effects of TEX was ascertained. In the single toxicant experiments, the toxicity of the three pollutants could be sequenced as ethylbenzene > xylene > toluene. Specifically, LC(50s) of T, E, and X after a 48-h exposure were 64.9, 37.8, and 42.0 mg/L, respectively. In the binary mixture experiments, the interaction between toluene and ethylbenzene, ethylbenzene and xylene, and toluene and xylene was largely in conformity with partial additive or additive effect as determined by isobologram representation and toxic unit models. In the ternary mixture experiments, the interaction was basically dependent on the use of additive index and mixture toxicity index methods. However, the antagonistic and synergistic actions were not significant. Thus, the tertiary mixture interaction could be regarded as additive action. The concentration addition model could successfully predict the joint action of TEX mixtures on C. plumosus larvae. Particularly, the additive action of TEX on C. plumosus larvae can be further recommended to evaluate water quality criteria of TEX.
水生生态系统容易受到石化污染物（如甲苯、乙苯和二甲苯（邻、间和对二甲苯））的暴露，以及这些污染物的不良影响。考虑到 TEX 的广泛使用、存在和高毒性，本工作旨在研究 TEX 对摇蚊幼虫（Chironomus plumosus）的差异毒性，并利用预测浓度加和模型揭示 TEX 二元和三元混合物的联合作用。更重要的是，本研究可以为建立水质标准或基准、水污染控制和水生风险评估提供基本的毒性数据和科学参考。采用半静态生物测定法研究了 TEX 对 C. plumosus 幼虫的单一和联合毒性作用，并确定了 TEX 的联合作用类型。在单一毒物实验中，三种污染物的毒性可以按顺序排列为乙苯>二甲苯>甲苯。具体来说，48 小时暴露后 T、E 和 X 的 LC50 分别为 64.9、37.8 和 42.0mg/L。在二元混合物实验中，甲苯和乙苯、乙苯和二甲苯以及甲苯和二甲苯之间的相互作用，根据等对数图表示和毒性单位模型，主要符合部分加性或加性效应。在三元混合物实验中，相互作用基本取决于加性指数和混合物毒性指数方法的使用。然而，没有明显的拮抗和协同作用。因此，三元混合物的相互作用可以被认为是加性作用。浓度加和模型可以成功地预测 TEX 混合物对 C. plumosus 幼虫的联合作用。特别是，TEX 对 C. plumosus 幼虫的加性作用可以进一步推荐用于评估 TEX 的水质标准。
