毒死蜱在我国水稻上登记现状及水生态风险评估

对中国目前在水稻上登记的所有毒死蜱单剂进行梳理统计，利用Top-Rice模型对不同剂型毒死蜱产品及其代谢物进行水生态风险评估.结果显示，截止2019年5月，我国在水稻上所登记的毒死蜱单剂共292种，分为6种剂型.乳油占比最大，为82.5%，其次为水乳剂，占12.0%，可湿性粉剂、微乳剂、微囊悬浮剂、颗粒剂分别占0.3%、4.1%、0.7%、0.3%.基于风险评估保守性原则，归纳出适用模型分析的不同剂型毒死蜱产品的施用方法模式，对其在水稻田使用进行暴露分析.结果显示6种不同剂型毒死蜱在不同场景、不同季节的水稻上施用后，其母体预测环境浓度（PEC）范围0.7~1628.6μg/L，其代谢物的PEC范围为0.7~1705.9μg/L.风险表征结果显示，在现有登记施用条件下，对初级急性风险而言，毒死蜱产品对鱼类、无脊椎动物风险组（RQ > 1）分别占总模拟组的76.0%、90.6%；对于初级慢性风险而言，毒死蜱对初级生产者的风险组占总模拟组的72.9%，而高级分析评估结果显示毒死蜱产品对鱼类、无脊椎动物及水生中宇宙组RQ值均大于1，对水生生态系统存在风险.综合以上结果，目前在我国水稻上登记的毒死蜱产品使用后对水生生态系统的风险不容忽视.需注意的是，为综合分析所有登记毒死蜱产品剂型的可能风险，本研究针对其施药方法模式的分析偏保守，且所用模型未考虑到毒死蜱在土壤表面光解等影响因素，使得评价结果具有一定保守性.

Registration status of chlorpyrifos products for use on rice and its risk assessment for aquatic ecosystem in China

In the present study, the current situation of chlorpyrifos products registered for use on rice in China was analyzed and the comprehensive risk assessment of products for aquatic ecosystem were conducted by using the Top-Rice model. It showed that a total of 292 chlorpyrifos formulations (single active component) had been registered for use on rice by May 2019 and these chlorpyrifos products could be grouped into six dosage forms. Among these forms, the emulsifiable concentrates (EC) accounted for the largest portion at 82.5%, followed by the water emulsions (EW) at 12.0%. And the wettable powders (WP), microemulsion (ME), microcapsule suspension (CS) and granules (GR) contributed to the remaining shares at 0.3%, 4.1%, 0.7% and 0.3%, respectively. Based on the conservative principles of risk assessment, application range of different dosage forms of chlorpyrifos and exposure assessment for their use on rice in China were investigated. The results showed that after applying six different dosage forms of chlorpyrifos on rice in different scenarios and seasons, the predicted environmental concentration (PEC) of parent compound chlorpyrifos ranged from 0.7 to 1628.6 μg/L and its metabolites ranged from 0.7 to 1705.9 μg/L. The results of acute risk characterization indicated that the at-risk groups of chlorpyrifos to fish and invertebrates accounted for 76.0% and 90.6%, respectively, of the total simulated group in current application conditions. By contrast, for chronic risk, the at-risk groups of chlorpyrifos to primary producers accounted for 72.9% of the total simulation group. The results of high tiered risk assessment showed that the RQ values of fish, invertebrates and aquatic mesocosm groups were all greater than 1. In summary, the risk to aquatic ecosystems resulted from using currently registered chlorpyrifos products on rice cannot be ignored in China. It should be noted that, in the present study, the method used to analyze the application model of all chlorpyrifos product dosage forms was relatively conservative and the Top-Rice model did not consider the factors affecting the photolysis of chlorpyrifos on the soil surface, therefore to some extent the risk might be underestimated based on the assessment results.