Hommen Udo, Schmitt Walter, Heine Simon, Brock Theo Cm, Duquesne Sabine, Manson Phil, Meregalli Giovanna, Ochoa-Acuña Hugo, van Vliet Peter, Arts Gertie
Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Schmallenberg, Germany.
Bayer CropScience AG, Monheim am Rhein, Germany.
Integr Environ Assess Manag. 2016 Jan;12(1):82-95. doi: 10.1002/ieam.1715. Epub 2015 Dec 14.
This case study of the Society of Environmental Toxicology and Chemistry (SETAC) workshop MODELINK demonstrates the potential use of mechanistic effects models for macrophytes to extrapolate from effects of a plant protection product observed in laboratory tests to effects resulting from dynamic exposure on macrophyte populations in edge-of-field water bodies. A standard European Union (EU) risk assessment for an example herbicide based on macrophyte laboratory tests indicated risks for several exposure scenarios. Three of these scenarios are further analyzed using effect models for 2 aquatic macrophytes, the free-floating standard test species Lemna sp., and the sediment-rooted submerged additional standard test species Myriophyllum spicatum. Both models include a toxicokinetic (TK) part, describing uptake and elimination of the toxicant, a toxicodynamic (TD) part, describing the internal concentration-response function for growth inhibition, and a description of biomass growth as a function of environmental factors to allow simulating seasonal dynamics. The TK-TD models are calibrated and tested using laboratory tests, whereas the growth models were assumed to be fit for purpose based on comparisons of predictions with typical growth patterns observed in the field. For the risk assessment, biomass dynamics are predicted for the control situation and for several exposure levels. Based on specific protection goals for macrophytes, preliminary example decision criteria are suggested for evaluating the model outputs. The models refined the risk indicated by lower tier testing for 2 exposure scenarios, while confirming the risk associated for the third. Uncertainties related to the experimental and the modeling approaches and their application in the risk assessment are discussed. Based on this case study and the assumption that the models prove suitable for risk assessment once fully evaluated, we recommend that 1) ecological scenarios be developed that are also linked to the exposure scenarios, and 2) quantitative protection goals be set to facilitate the interpretation of model results for risk assessment.
环境毒理学与化学学会（SETAC）研讨会MODELINK的本案例研究表明，利用大型植物的机理效应模型可将实验室测试中观察到的植物保护产品效应外推至田间边缘水体中大型植物种群动态暴露所产生的效应。基于大型植物实验室测试对一种示例除草剂进行的标准欧盟风险评估表明，在几种暴露场景下存在风险。使用两种水生大型植物的效应模型对其中三种场景作进一步分析，这两种水生大型植物分别是漂浮的标准测试物种浮萍属植物，以及扎根于沉积物中的沉水附加标准测试物种狐尾藻。这两个模型均包括一个描述毒物吸收和消除的毒代动力学（TK）部分、一个描述生长抑制的内部浓度 - 反应函数的毒效动力学（TD）部分，以及一个将生物量增长描述为环境因素函数的部分，以模拟季节动态。TK - TD模型通过实验室测试进行校准和检验，而生长模型基于与田间观察到的典型生长模式的预测比较，假定适用于此目的。对于风险评估，预测了对照情况和几种暴露水平下的生物量动态。基于大型植物的特定保护目标，提出了用于评估模型输出的初步示例决策标准。这些模型对较低层级测试所表明的两种暴露场景的风险进行了细化，同时确认了与第三种场景相关的风险。讨论了与实验和建模方法及其在风险评估中的应用相关的不确定性。基于本案例研究以及一旦全面评估模型就证明其适用于风险评估的假设，我们建议：1）制定与暴露场景相关的生态场景；2）设定定量保护目标，以促进对风险评估模型结果的解释。
