噻虫嗪在水稻中的消解动态及风险评估

Dissipation dynamic and risk assessment of thiamethoxam in rice

为评价20%噻虫嗪悬浮剂在水稻上使用的安全性,于安徽、吉林两地进行田间试验,采用高效液相色谱-紫外分析法研究噻虫嗪在水稻植株、稻秆、稻壳和糙米中的消解动态和最终残留.结果表明:所建立的甲醇-二氯甲烷(1∶1,v∶v)混合液具有良好的洗脱效果;噻虫嗪在植株中的消解规律符合一级动力学模型,其在安徽、吉林两地间水稻植株中的半衰期分别为2.1 d和5.6 d;按推荐剂量施药,糙米中噻虫嗪的最终残留量最高为1.0 mg.kg-1;推算每人经水稻摄入噻虫嗪日均仅为0.4 mg,风险商值(RQ)为0.32,处于安全水平.

To evaluate the application safety of thiamethoxam 20% SC, the terminal residue and dissipation dynamic of thiamethoxam in rice plant, rice straw, rice hulls and brown rice in Anhui and Jilin provinces were investigated and the samples were analyzed by HPLC-UVD. The results showed that the established methanol-methylene chloride mixture （ 1 ： 1, v ： v ） had good elution effect ; the dissipation curves of thiamethoxam in rice plant fitted to the first-order kinetics; the half-life of thiamethoxam was 2.1 d and 5.6 d in rice plant in Anhui and Jilin provinces respectively. When the formulation was sprayed at the recommended dosage, the final residues of thiamethoxam in brown rice was up to 1.0 mg·kg^-1. By calculating, the daily average intakes of thiamethoxam from rice was only 0.4 mg per person and the risk quotient（RQ） was 0.32, so the application was safe.