Ashauer Roman, Boxall Alistair B A, Brown Colin D
Environment Department, University of York, Heslington, York, YO10 5DD, United Kingdom.
Environ Sci Technol. 2007 Aug 1;41(15):5535-41. doi: 10.1021/es070283w.
Aquatic risk assessment can be improved if we are able to quantitatively predict the effects resulting from sequential pulsed exposure to multiple compounds. We evaluate two modeling approaches, both extended to suit multiple compounds, the semi-mechanistic threshold damage model (TDM), and a model based on time-weighted averages (TWA). The TDM predicts that recovery of damage to Gammarus pulex from exposure to chlorpyrifos takes longer than that from exposure to carbaryl and consequently that the sequence of exposure matters. We measured survival of the freshwater invertebrate Gammarus pulex after sequential pulsed exposure to carbaryl and chlorpyrifos. Two groups of organisms were exposed to a first pulse of either carbaryl or chlorpyrifos for 1 day and then, after a recovery period of two weeks, to a second pulse with the other compound. The comparison of mortalities caused by each pulse, as well as combined mortalities in both treatments, show that the sequence of exposure to pulses of contaminants does indeed matter. Previous exposure to chlorpyrifos leads to significantly increased mortality from subsequent pulses of carbaryl, but not the other way round. The TDM facilitates a process-based ecotoxicological explanation by simulating the recovery dynamics and outperforms the TWA model.
如果我们能够定量预测连续脉冲暴露于多种化合物所产生的影响，水生风险评估就能得到改进。我们评估了两种建模方法，这两种方法都进行了扩展以适用于多种化合物，即半机械阈值损伤模型（TDM）和基于时间加权平均值（TWA）的模型。TDM预测，从毒死蜱暴露中恢复对蚤状溞造成的损伤所需时间比从西维因暴露中恢复所需时间更长，因此暴露顺序很重要。我们测量了淡水无脊椎动物蚤状溞在连续脉冲暴露于西维因和毒死蜱后的存活率。两组生物先暴露于西维因或毒死蜱的第一个脉冲1天，然后在两周的恢复期后，再暴露于另一种化合物的第二个脉冲。对每个脉冲导致的死亡率以及两种处理中的综合死亡率进行比较，结果表明污染物脉冲的暴露顺序确实很重要。先前暴露于毒死蜱会导致后续西维因脉冲造成的死亡率显著增加，但反之则不然。TDM通过模拟恢复动态促进了基于过程的生态毒理学解释，并且优于TWA模型。
