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研究报告

摘要：为了评价嘧草醚在水稻生长过程中使用的安全性，于2018—2019年分别在佳木斯、济宁、南昌、宁波4地进行了为期2年的田间试验，研究了嘧草醚在田水、土壤、稻株中的消解动态及稻米、稻壳、稻杆中的最终残留.结果表明：嘧草醚在田水、土壤及稻株中的消解规律均符合一级动力学模型，在4地田水中的消解半衰期（t_1/2）为1.07~3.48 d，土壤中的消解半衰期（t_1/2）为3.14~5.42 d，稻株中的消解半衰期（t_1/2）为4.47~8.08 d.通过对消解半衰期与土壤性质和气候条件的线性回归分析可得，嘧草醚在不同基质中的消解速率均与土壤有机质含量和平均气温呈显著相关.施用1.5倍或2倍推荐使用剂量的嘧草醚后（90或120 g·hm^-2），收获的稻米籽实中检测出嘧草醚的残留量均未超过日本和韩国规定的最大残留限量（MRL）值（0.05 mg·kg^-1）.通过计算得出每人每天从稻米中所摄入的嘧草醚为0.0037 mg，其风险商值（RQ）为0.0028，处于安全水平.

Abstract：In order to evaluate the safety of pyriminobac-methyl in rice planting, field experiments were conducted in Jiamusi, Jining, Nanchang and Ningbo for two years in 2018—2019. The degradation dynamics of pyriminobac-methyl in field water, soil, and rice plant and the final residues in rice, rice husk and rice stalk were investigated. The results show that the degradation dynamics of pyriminobac-methyl in field water, soil and rice plant are well fit by the first-order kinetics. The degradation half-lives (t_1/2) of pyriminobac-methyl in field water, soil and rice plant collected from four experimental fields were 1.07~3.48 d, 3.14~5.42 d, and 4.47~8.08 d, respectively. Through the linear regression analysis of the degradation half-life and soil properties/climatic conditions, it can be concluded that that the digestion rates of pyriminobac-methyl in different substrates were significantly related to the content of organic matter in soil and the average climate temperature. When applying 1.5 or 2.0 times of the recommended dose of pyriminobac-methyl (90 or 120 g a. i·hm^-2), the residual content of pyriminobac-methyl in rice didn't exceed the maximum residue limit (MRL) value (0.05 mg·kg^-1) specified by Japan and Korea. It is estimated that the daily uptake of pyriminobac-methyl from rice was 0.0037 mg, and the risk quotient (RQ) was 0.0028, which was in a safe level.