Radboud University Nijmegen, Institute for Water and Wetland Research, Department of Environmental Science, P.O. Box 9010, 6500 GL, Nijmegen, The Netherlands.
Chemosphere. 2013 Sep;93(2):366-72. doi: 10.1016/j.chemosphere.2013.05.007. Epub 2013 Jun 2.
Since chemicals' ecotoxic effects depend for most soil species on the dissolved concentration in pore water, the equilibrium partitioning (EP) method is generally used to estimate hazardous concentrations (HC50) in the soil from aquatic toxicity tests. The present study analyzes the statistical uncertainty in terrestrial HC50s derived by the EP-method. For 47 organic chemicals, we compared freshwater HC50s derived from standard aquatic ecotoxicity tests with porewater HC50s derived from terrestrial ecotoxicity tests. Statistical uncertainty in the HC50s due to limited species sample size and in organic carbon-water partitioning coefficients due to predictive error was treated with probability distributions propagated by Monte Carlo simulations. Particularly for specifically acting chemicals, it is very important to base the HC50 on a representative sample of species, composed of both target and non-target species. For most chemical groups, porewater HC50 values were approximately a factor of 3 higher than freshwater HC50 values. The ratio of the porewater HC50/freshwater HC50 was typically 3.0 for narcotic chemicals (2.8 for nonpolar and 3.4 for polar narcotics), 0.8 for reactive chemicals, 2.9 for neurotoxic chemicals (4.3 for AChE agents and 0.1 for the cyclodiene type), and 2.5 for herbicides-fungicides. However, the statistical uncertainty associated with this ratio was large (typically 2.3 orders of magnitude). For 81% of the organic chemicals studied, there was no statistical difference between the hazardous concentration of aquatic and terrestrial species. We conclude that possible systematic deviations between the HC50s of aquatic and terrestrial species appear to be less prominent than the overall statistical uncertainty.
由于大多数土壤物种的化学物质的生态毒性效应取决于孔隙水中的溶解浓度，因此通常使用平衡分配（EP）方法来根据水生毒性测试估算土壤中的危险浓度（HC50）。本研究分析了通过 EP 方法得出的陆地 HC50 的统计不确定性。对于 47 种有机化学品，我们比较了来自标准水生生态毒性测试的淡水 HC50 和来自陆地生态毒性测试的孔隙水 HC50。由于物种样本量有限和有机碳-水分配系数预测误差而导致的 HC50 统计不确定性，通过蒙特卡罗模拟传播的概率分布进行了处理。特别是对于特定作用的化学品，根据由目标和非目标物种组成的代表性物种样本来确定 HC50 非常重要。对于大多数化学物质组，孔隙水 HC50 值比淡水 HC50 值高约 3 倍。孔隙水 HC50/淡水 HC50 的比值通常为麻醉性化学品（非极性为 2.8，极性为 3.4）的 3.0，反应性化学品的 0.8，神经毒性化学品（AChE 制剂为 4.3，环二烯型为 0.1）的 2.9 和除草剂-杀真菌剂的 2.5。但是，与该比率相关的统计不确定性很大（通常为 2.3 个数量级）。在所研究的有机化学品中，有 81％的化学品在水生和陆地物种的危险浓度之间没有统计学差异。我们的结论是，水生和陆地物种的 HC50 之间可能存在系统偏差，但似乎不如整体统计不确定性那么明显。
