中国水稻上登记吡虫啉单剂的水生生态风险评估

为评估吡虫啉药剂对水生生态系统的风险，对目前中国水稻上登记使用的吡虫啉单剂品种进行了梳理，基于风险评估保守性的原则，归纳出不同剂型产品所适用的施用量，采用Top-Rice模型和风险商值 (RQ)法，对现有吡虫啉单剂产品进行了水生生态风险评估。结果显示:截至2020年6月，近3年中国水稻上登记的有效吡虫啉单剂产品共375种，其中可湿性粉剂(WP)占比最大，为56.53%；其次为可溶液剂(SL)，占11.47%；乳油(EC)、悬浮剂(SC)、水分散粒剂(WG)、微乳剂(ME)、悬浮种衣剂(FS)、泡腾片剂(EB)、片剂(TA)、种子处理可分散粉剂(WS) 分别占9.87%、8.27%、8.00%、3.73%、1.33%、0.27%、0.27%和0.27%。水生生态风险评估结果表明:7种吡虫啉单剂产品在各种场景-时间点施用后，其预测环境浓度(PEC)范围为质量浓度0.19 ~ 51.28 μg/L；在现有登记施用条件下，对鱼类和无脊椎动物的急性暴露风险均可接受；就慢性暴露风险而言，对鱼类和初级生产者的慢性暴露风险均可接受，而对以大型溞和溪流摇蚊为代表的无脊椎生物，仅13.58%的模拟组其 RQ 值小于1，故具有一定的潜在风险。研究结果表明，按照目前登记的施用方法，吡虫啉单剂产品在水稻上使用时对水生生态系统存在一定的风险，但需要说明的是，为综合评价吡虫啉单剂产品对水生生态系统可能产生的风险，本研究中对施用方法的取值分析偏保守，且由于代谢物数据不充分，使得评估结果存在一定的不确定性。

Aquatic ecological risk assessment of single-dose imidacloprid registered on rice of China

In order to evaluate the risk of the use of single-dose imidacloprid products to aquatic ecosystem, based on the conservative principles of risk assessment, different application rates of imidacloprid formulations registered on rice were evaluated and subsequently, the comprehensive risk assessment of these products to aquatic ecosystem was performed using the Top-Rice model and the risk quotient method. These results showed that a total of 375 imidacloprid formulations (single active component) had been registered on rice by June 2020, which could be separated into ten formulation groups. Among these formulations, the wettable powders (WP) accounted for the largest portion at 56.53%, followed by the soluble concentrate (SL) at 11.47%. And the emulsifiable concentrates (EC), suspension concentrate (SC), water dispersible granule (WG), microemulsion (ME), flowable concentrate for seed treatment (FS), effervescent tablet (EB), tablet (TA) and water dispersible powder for slurry seed treatment (WS) were 9.87%, 8.27%, 8.00%, 3.73%, 1.33%, 0.27%, 0.27% and 0.27%, respectively. These results showed that the predicted environmental concentration (PEC) of imidacloprid products ranged from 0.19 to 51.28 μg/L after applying different formulations of imidacloprid on rice in different scenes and seasons. In addition, the risk characterization results demonstrated that the risks of acute exposure to imidacloprid products to fish and invertebrates and that of chronic exposure to fish and primary producers were acceptable under existing registration conditions. However, there were potential chronic risks to Daphnia magna and Chironomus riparius as a result of only 13.58% of the simulated groups in which the risk quotient (RQ) was less than 1. These results suggested the currently imidacloprid products registered in China posed a certain risk to aquatic ecosystem according to the current registration application conditions. In the present study, it should be noted that the assessment method used to analyze the application model of all imidacloprid product formulations was relatively conservative, and the metabolite had not been analyzed because of its insufficient data. Therefore, these factors mentioned above made the evaluation results relatively conservative.