Modifying factors of toxicant impacts on biota

我的实验室环境毒理学项目的长期目标是：1)了解改变有毒化学物质对生物群影响的因素（环境和生理），2)开发评估污染物对自由生物影响的方法，以及3)开发和测试预测有毒混合物对水生生物毒性的模型。在特定地点的定量环境风险评估中，了解修饰因素对于将实验室毒理学数据应用于现场，或将在一个地点收集的现场数据应用于另一个地点，以保护环境至关重要。在我的职业生涯中观察各种修饰因素的影响时，很明显，我们正在研究的是环境因素如何改变化学品的生物利用度：暴露浓度、时间和同化/净化动力学如何相互作用，以达到生物体中的临界（毒性阈值）化学浓度。使用这种方法开发的模型在环境毒理学的假设制定和测试之间提供了确定的联系。我们已经使用这种方法在实验室和现场描述了沉积物中单一金属对底栖无脊椎动物的毒性和生物利用度，饮食和水生金属对底栖无脊椎动物毒性的相对贡献，以及几种水生金属对水生生物的急性和慢性毒性（主要通过使用生物配体模型的原理）。在下一个周期中，我们将着眼于改进和测试我们开发的模型，该模型可以预测混合物中多达10种金属对阿兹特克透明菌的毒性。在第二个研究领域，我们将研究选定的金属和烷基化多环芳烃在水蚤混合毒性实验中的相互作用。我们还将评估遗传背景对片足类动物对金属暴露的耐受性的影响。总的来说，这项工作有助于我们对环境污染物的影响的基本理解，并有助于健全以科学为基础的加拿大环境法规。

The long-term objectives of my laboratory's program in environmental toxicology are: 1) to understand the factors (environmental and physiological) that modify the impacts of toxic chemicals on biota, 2) to develop methods to assess contaminant impacts on free-living organisms, and 3) to develop and test models predictive of the toxicity of toxicant mixtures to aquatic organisms. An understanding of modifying factors is crucial for the application of laboratory toxicology data to the field, or the application of field data collected at one site to another, during site-specific quantitative environmental risk assessment to protect the environment. While looking at the effects of various modifying factors over my career, it has become evident that what we are looking at is how environmental factors modify the bioavailability of a chemical: how exposure concentration, time and assimilation/depuration kinetics interact to achieve a critical (threshold of toxicity) chemical concentration in the organism. Models developed using this approach provide a deterministic link between hypothesis formulation and testing in environmental toxicology. We have used this approach to characterize the toxicity and bioavailability of single metals from sediments to benthic invertebrates in both the laboratory and the field, the relative contributions of dietary versus waterborne metals to toxicity in benthic invertebrates, and the acute and chronic toxicity of several waterborne metals to aquatic biota (largely through the use of the principles of the Biotic Ligand Model). In the next cycle we will look at refining and testing a model which we have developed to predict the toxicity to Hyalella azteca of up to ten metals in a mixture. In a second area of research, we will look at the interaction of selected metals and alkylated polycyclic aromatic hydrocarbons in mixture toxicity experiments with Daphnia magna. We will also assess the effect of genetic background on tolerance to metal exposure within the amphipod genus Hyalella. Overall, the work contributes to our basic understanding of the impact of environmental contaminants, and to sound scientifically-based Canadian environmental regulations.