代森锌及其代谢物乙撑硫脲在食用百合上的残留行为与膳食风险评估

目前代森锌在百合上尚未登记，缺少安全间隔期等相关信息，可能会导致生产中超范围盲目用药。为明确代森锌在百合上的残留风险，通过田间消解和最终残留试验，研究了代森锌在食用百合上的残留特征并对其膳食风险进行了评估。结果表明:代森锌在百合中的消解动态符合一级反应动力学模型，其消解半衰期在江苏试验点为5.9 d，湖南试验点为3.8 d。采用65%代森锌可湿性粉剂，按最高推荐剂量 (有效成分3000 g/hm2) 及其1.5 倍剂量 (有效成分4500 g/hm2)，在江苏、湖南、湖北和四川4地的百合上施用，距末次施药后7、14和21 d，4地的最高残留值 (以CS₂计)鲜百合中为0.260 mg/kg，干百合中为1.290 mg/kg，均低于我国制定的鲜百合 ( 0.5 mg/kg )和干百合 ( 2 mg/kg )中代森锌的最大残留限量 (MRL)值。代森锌极易降解为乙撑硫脲 (ETU)，而ETU在鲜百合样品中有检出，因此对百合中代森锌及其代谢物ETU的膳食摄入风险进行了评估，结果显示:代森锌及ETU在鲜百合和干百合中的慢性膳食摄入风险占每日允许摄入量 (ADI)的比值分别为0.014%和 < 0.014%，总体对膳食风险的贡献较小。研究表明，按照推荐剂量规范使用，代森锌在百合中的残留量一般不会对我国人群的健康产生不可接受的影响。

Residue behavior and dietary risk assessment of zineb and its metabolite ethylene thiourea in edible lily

At present, zineb has not been registered on edible lily in China, and the lack of pre-harvest intervals and other relative information may lead to irrational use of pesticides and high residue risks. In order to determine the residue risks of zineb on edible lily, the residue dissipation and dietary risks of zineb residues were evaluated in field trials. The results showed that the degradation of zineb in lily conformed to the first-order kinetic equation, and the half-lives in Jiangsu and Hunan Provinces were 5.9 and 3.8 days, respectively. To investigate the terminal residues in the field trial, the recommended dosage (3000 g a.i./hm2) and 1.5 times recommended dosage (4500 g a.i./hm2) of 65% zineb wettable powder were sprayed three or four times on lily crops at four locations. At 7, 14 and 21 days after the last application, the maximum residues of zineb (calculated by CS₂) in harvested fresh lily and dried lily were 0.260 mg/kg and 1.290 mg/kg, respectively, both of which were lower than the maximum residue limits (MRL) of zineb in China on fresh lily (0.5 mg/kg) and dried lily (2 mg/kg). Because zineb is easily degraded to ethylene thiourea (ETU), and the ETU was detected in the samples of fresh lily, the dietary intake risks of zineb and its metabolite ETU in lily were analyzed. The results of the dietary risk assessment suggested that the ratios of dietary intake risk of zineb to the acceptable daily intake (ADI) in fresh and dried lilies were 0.014% and < 0.014%, respectively, which contributed very little to the overall dietary exposure. These results showed that the residues of Zineb in edible lily would not have an unacceptable risk to Chinese people when Zineb formulation was applied at the recommended dose.