Olmstead Allen W, LeBlanc Gerald A
Department of Environmental and Molecular Toxicology, North Carolina State University, Raleigh, North Carolina 27695, USA.
Integr Environ Assess Manag. 2005 Apr;1(2):114-22. doi: 10.1897/ieam_2004-005r.1.
In this study, 9 chemicals were chosen from a recent report on surface water concentrations of a variety of xenobiotics to test the hypothesis that the toxicity of chemical mixtures could be estimated using a model based on the toxicity of the individual chemicals. Concentration-response curves for the endpoints of lifespan, growth rate, and fecundity were generated for each chemical experimentally using the crustacean, Daphnia magna. From this data, a mathematical model for the combined toxicity of these chemicals was generated that merged the concepts of concentration addition and independent joint action. Toxicity of a mixture was modeled at various levels at which the ratio of the chemicals within the mixture was maintained at that reported for median detected environmental levels. Toxicity of the mixture was then determined experimentally and compared to model predictions. The model accurately predicted the most sensitive endpoint, as well as the lowest toxic effect level of the mixture. Results demonstrated that, for this mixture of chemicals, toxicity was not influenced significantly by interactions among the chemicals and a single constituent dominated toxicity. According to model predictions and experimental results, the median detected environmental concentrations of chemicals constituting this mixture provided no margin of safety.
在本研究中，从最近一份关于各种外源生物地表水浓度的报告中选取了9种化学物质，以检验如下假设：化学混合物的毒性可使用基于各单一化学物质毒性的模型来估算。使用甲壳纲动物大型溞，通过实验得出了每种化学物质关于寿命、生长速率和繁殖力终点的浓度-反应曲线。根据这些数据，生成了一个关于这些化学物质联合毒性的数学模型，该模型融合了浓度相加和独立联合作用的概念。在混合物中化学物质比例保持为报告的环境检测中位数水平的各种浓度下，对混合物的毒性进行建模。然后通过实验确定混合物的毒性，并与模型预测结果进行比较。该模型准确预测了最敏感的终点以及混合物的最低毒性效应水平。结果表明，对于这种化学物质混合物，化学物质之间的相互作用对毒性没有显著影响，单一成分主导了毒性。根据模型预测和实验结果，构成该混合物的化学物质在环境中的检测中位数浓度没有提供安全边际。
