Study On Dietary Risk Assessment And Degradation Model Of Pesticide Residues In Cowpea Production

PurposeOne of the purpose of this study was to explore the sample pretreatment method of pesticide residues in cowpea to realize the simultaneous detection of multiple pesticides,analyze the pesticide residues in cowpea production,and calculate the dietary risk of pesticide residues on the population.Another purpose was to explore the degradation and residue of triadimefon in cowpea cultivation process,and establish a new pesticide residue degradation model.MethodThree main planting cities and counties were selected as sample sources by stratified sampling method.The pesticides in cowpeas were detected by QuEChERS-liquid chromatography tandem mass spectrometry.The pesticide residues in cowpeas were analyzed according to the detection results.The acute,chronic and compound dietary risk assessment of the pesticides in cowpeas was carried out.The degradation model was established by polynomial equation to carry out a relevant study on the field degradation dynamics of zolamide in cowpeas.ResultSix pesticides tested in this study showed a good linear relationship with the recovery rate under the selected pretreatment and detection methods.The average recovery of the method is between 71%and 115%,and the relative standard deviation(n=3)is between 0.2%and 8.8%.A total of 243 samples were tested this time,with the highest detection rate of 37%for chlorpyrifos and 13.17%for pyrazolin.There are multiple pesticide residues in three cities.In city C,the%ADI of zolamide is 1.1791>1,the HI of city C is 1.9036,and the HI of city A is 1.3337.There is no acute dietary risk in the three cities.A polynomial degradation model was established to predict pesticide residues.The fitting curve of zolamide on cowpea was obtained:C=-0.2804·t~3+9.904·t~2-115.7·t+553.7,R~2=0.99.ConclusionA method for the simultaneous determination of 6 pesticide residues in cowpea was established.Among cowpeas in the three cities,cyromazine was used the most,and the number of samples exceeding the standard was the highest for the inhalable fungicide pyrazolate,with a total of 32 samples exceeding the standard.Under the same sample size,the number of endothermic pesticides exceeding the standard is greater than that of non-endothermic pesticides.There are multiple pesticide residues in all cities.Only one pesticide is used in cities A and B,accounting for the largest proportion,while city C uses two pesticides at the same time,accounting for the largest proportion.There is a certain chronic dietary risk of zolamide in City C%ADI is 1.1791>1,there is a certain compound risk in City A and C,and there is no compound risk in City B.There is no acute dietary risk in the three cities.A polynomial degradation model was established to predict pesticide residues.