除虫脲在棉叶和土壤中消解动态分析及棉子中残留量膳食摄入评估

目的评价除虫脲在棉叶、土壤中的消解趋势和土壤及棉子中的残留水平。方法棉叶、土壤样品经乙腈提取、氯化钠盐析、弗罗里硅土固相萃取柱净化后,采用高效液相色谱-光电二极管阵列检测器检测;同时对2014年和2015年除虫脲在河南和北京两地棉叶及土壤中的残留消解动态进行分析并对棉子中的最终残留量进行膳食摄入评估。结果除虫脲在棉子、棉叶和土壤空白样品添加的平均回收率在79%~103%之间,相对标准偏差在3%~15%之间,最低检测浓度均为0.1 mg/kg。棉叶中除虫脲的残留消解半衰期在5.0~8.6 d之间,土壤中残留消解半衰期在3.8~14 d之间。按本试验方式进行施药及采样后,棉子中除虫脲的最终残留量低于0.1 mg/kg,土壤中的残留量低于0.19 mg/kg。结论除虫脲普通人群的国家估计每日摄入量是0.873229mg/kg·bw,占日允许摄入量的69.3%左右,认为对一般人群健康不会产生不可接受的风险。

Dissipation dynamics analysis of diflubenzuron in cotton leaves and soil under field conditions and risk assessment for dietary residue intake

Objective The purpose was to determine whether diflubenzuron usage was safe under the recommended dosage. We established an analytical method and investigated the dissipation dynamics and terminal residues of diflubenzuron in cotton crops and in soil under field conditions. Methods The residue levels and dissipation rates of diflubenzuron in cotton and soil were determined by ultra performance liquid chromatography using photo-diode array (UPLC-PDA). Results At fortification levels of 0.1, 1 and 40 mg/kg in cotton leaves and of 0.1, 1 and 2 mg/kg in cotton seeds and in soil, recoveries were shown to range from 79 to 103 percent, with a relative standard deviation (RSD) of 3 to 15 percent. The limits of quantification (LOQ) were 0.1 mg/kg for soil, cotton leaves and cotton seeds. The dissipation half-lives of diflubenzuron in cotton leaves and in soil were 5.0-8.6 days and 3.8-14 days, respectively. The terminal residues at harvest in cotton seeds and in soil were lower than 0.1 mg/kg and 0.19 mg/kg, respectively. Percent acceptable daily intake (ADI) being 69.3% was less than 100% since the supervised trial median residue (STMR) in cotton seeds was 0.1 mg/kg and the general population of diflubenzuron national estimated daily intake was 0.87 mg. Result of risk assessment of supervised residue trial indicated that the potential health risk induced by diflubenzuron was not significant. Conclusion Our recommendations are that diflubenzuron be applied to cotton crops at a dosage of 150 g/hm2 using a pre-harvest interval (PHI) of at least 14 days between the last application and the harvest. These results would help the government to establish the MRL of diflubenzuron in cotton and to provide guidance concerning the proper and safe use of diflubenzuron.