Department of Basic Sciences and Environment, Faculty of Life Sciences, University of Copenhagen, Thorvaldsensvej 40, DK-1871 Frederiksberg, Denmark.
Aquat Toxicol. 2011 Jan 25;101(2):412-22. doi: 10.1016/j.aquatox.2010.11.004. Epub 2010 Nov 19.
Laboratory experiments have shown that azole fungicides enhance the toxic effect of pyrethroid insecticides towards the aquatic crustacean Daphnia magna. Due to their sorptive properties the pesticides may, however, be less bioavailable in natural environments, possibly rendering them less toxic to aquatic organisms. In the present study, the synergistic potential of azoles on pyrethroids in natural environments was assessed by treating 18 outdoor aquatic microcosms with concentrations of the pyrethroid esfenvalerate at 0.167, 0.333, or 0.833μg/L either alone or in combination with 90μg/L of the azole prochloraz. Pesticide concentrations and the zooplankton and phytoplankton communities were assessed prior to pesticide application and at days 0, 1, 2, 4, 7, 14, 21, and 28 after pesticide application. DT(50)-values for disappearance of the pesticides from the water of 4.7 days and 30h were observed for prochloraz and esfenvalerate, respectively. The monitored communities showed larger decreases in abundance of cladoceran, copepods, and chironomids in treatments with esfenvalerate in combination with prochloraz compared to treatments with esfenvalerate alone. No systematic effects were observed in populations of Ostracoda. Adverse effects on populations of cladocerans and copepods occurred between day 2 and day 7 and, though copepods in general were less sensitive than cladocerans to both esfenvalerate alone and in combination with prochloraz, the potentiation factors for the two taxa were similar. Thus, comparison of EC(20)-values estimated on the basis of concentration-response curves for days 2, 4, and 7 showed that prochloraz enhanced the toxicity of esfenvalerate four to sixfold for copepods and three to sevenfold for cladocerans. Rotifers were not significantly affected by any of the treatments, though there was a tendency of a population increase when cladoceran and copepod populations decreased. In all invertebrate populations that showed response to the pesticide treatments, indications of stabilisation or the beginning of recovery occurred between day 7 and day 14 and full recovery was observed in some of the less affected populations of cladocerans, copepods, and chironomids after 28 days. The occurrence of the synergistic interactions between prochloraz and esfenvalerate in the microcosms and at environmentally realistic concentrations implies that the synergistic interactions may also take place in invertebrate communities in natural ponds and ditches being exposed to azoles and pyrethroids via for example runoff or drift. The question of how to deal with synergy between chemicals in the environment from a regulatory perspective is briefly discussed.
实验室实验表明，唑类杀菌剂会增强拟除虫菊酯类杀虫剂对水生甲壳类动物大型溞的毒性。然而，由于其吸附特性，农药在自然环境中的生物利用度可能较低，从而降低其对水生生物的毒性。在本研究中，通过用浓度为 0.167、0.333 或 0.833μg/L 的拟除虫菊酯类药剂 esfenvalerate 单独处理或与 90μg/L 的唑类药剂 prochloraz 联合处理 18 个户外水生微宇宙，评估了唑类药剂在自然环境中对拟除虫菊酯类药剂的增效作用。在施药前和施药后第 0、1、2、4、7、14、21 和 28 天，评估了农药浓度以及浮游动物和浮游植物群落。观察到 prochloraz 和 esfenvalerate 的半衰期（DT50）分别为 4.7 天和 30 小时。监测到的群落中，与单独使用 esfenvalerate 相比，用 esfenvalerate 与 prochloraz 联合处理时，桡足类、桡足类和摇蚊科的数量减少幅度更大。在介形类动物种群中没有观察到系统效应。桡足类和桡足类种群在第 2 天至第 7 天之间出现了不良影响，尽管桡足类动物对单独使用 esfenvalerate 和与 prochloraz 联合使用均不如桡足类动物敏感，但这两个类群的增效因子相似。因此，基于第 2、4 和 7 天浓度-反应曲线估计的 EC20 值的比较表明，prochloraz 将 esfenvalerate 对桡足类动物的毒性增强了 4 至 6 倍，对桡足类动物的毒性增强了 3 至 7 倍。轮虫不受任何处理的显著影响，尽管桡足类动物和桡足类动物种群减少时，种群有增加的趋势。在对农药处理有反应的所有无脊椎动物种群中，在第 7 天至第 14 天之间出现了稳定或开始恢复的迹象，在一些受影响较小的桡足类动物、桡足类动物和摇蚊科种群中，28 天后完全恢复。在微宇宙中和在环境现实浓度下，prochloraz 和 esfenvalerate 之间增效作用的发生表明，增效作用也可能发生在暴露于唑类和拟除虫菊酯类的自然池塘和沟渠中的无脊椎动物群落中，例如通过径流或漂移。简要讨论了从监管角度考虑环境中化学物质协同作用的问题。
