Residue Dissipation And Dietary Risk Assessment Of Chlorfenapyr In Potato

Potato is an annual herb in the Solanaceae family.It is one of the four major food crops in the world together with rice,corn and wheat.It has strong adaptability,high yield per unit area and starch content,rich nutritional value and is easy to process,etc.It is one of the main staple food crops for expansion in China.With the expansion of potato planting area,potato pests and diseases are becoming more and more serious,which poses a great threat to the yield and quality of potato.Ladybird beetles are one of the main pests of potato.The larvae and adults of ladybird beetles feed on mesophyll and form a lot of irregular translucent leaves,which affect the accumulation of nutrients and greatly reduce the yield and quality of potato.At present,chemical control is the most effective,quick and convenient method to control the ladybird beetles.However,due to the irrational use of pesticides,it can lead to the pollution of agricultural products,which poses a threat to human health,destroys the agricultural production environment,and affects the sustainable development of agriculture.Therefore,it is necessary to carry out environmental behavior and dietary risk assessment before pesticide registration.In order to adapt to the actual needs of the domestic potato production,through two years in field experiments,The residual methods,digestion rules,final residual amount and risk assessment of chlorfenapyr on potato were studied,and the rational use criteria and reference limit of chlorfenapyr on potato were put forward.The research results are as follows:1.A gas chromatography-mass spectrometry（GC-MS）method was developed for the determination of chlorfenapyr residues in potatoes.Chlorfenapyr was extracted from potato tubers,potato plants and soil samples by a mixture of acetonitrile and water.Potato tubers and soil purification by Florisil SPE column and potato plants purification by Pesti Carb SPE column,gas chromatography-mass spectrometer was used for detection.The average recoveries of chlorfenapyr in potato tubers,plants and soil were 80.3%～93.2%,78.4%～95.8%and 91.2%～97.7%,and the relative standard deviations（RSDs）were 2.2%～6.0%,3.7%～7.1%and 1.0%～5.1%.The minimum detectable concentration of chlorfenapyr in potato tubers,potato plants and soil was 0.01 mg/kg.The method is rapid,accurate and has high recovery rate.It is suitable for the determination of chlorfenapyr residues in potato and adapt to the requirements of pesticide residue detection.2.The digestion dynamics of chlorfenapyr in potato plants and soil were determined.The digestion dynamics tests were carried out in Changchun,Jilin Province and Chifeng,Inner Mongolia from 2019 to 2020,and the half-lives of chlorfenapyr in potato plants and soil were 6.1-8.1 d and 15.8-19.8 d.The digestion half-life of chlorfenapyr was less than30 d.Chlorfenapyr was a readily degradable pesticide in potato plants and soil.3.Determine the final residue of chlorfenapyr in potato tubers,potato plants and soil.The final residue tests were carried out in Changchun,Jilin Province and Chifeng,Inner Mongolia for two years from 2019 to 2020,The dosage of 240 g/L chlorfenapyr suspension was 500 g/hm2（120 g a.i./hm²）,and the application method was stem and leaf spray,applied twice,and the application interval was 7 days.In 2019,the residues of chlorfenapyr in potato tubers,potato plants and soil were 0.091～0.120 mg/kg,0.760～26.255 mg/kg and 0.985～2.709 mg/kg.In 2020,the residues of chlorfenapyr in potato tubers,potato plants and soil were 0.090～0.123 mg/kg,0.708～20.408 mg/kg and 0.539～3.454 mg/kg.Based on the results of digestion test and final residue test,240 g/L chlorfenapyr suspension was recommended,and the maximum dosage was 500 g/hm2（120 g a.i./hm²）.At the initial stage of the disease,the spray was applied twice by stem and leaf spray method,and the application interval was 7 days.At present,the maximum residue limit of chlorfenapyr in potato has not been formulated in China,and combined with the results of this study,it is recommended that the maximum residue limit of chlorfenapyr in potato should be 0.5 mg/kg in China,and the safety interval should be 14days.4.Dietary risk assessment was carried out for chlorfenapyr in potato.According to the final residue test results from 2019 to 2020,dietary risk assessment was conducted.The results showed that the short-term dietary risk quotients and long-term dietary risk quotients of chlorfenapyr in potato were 3.22×10^-3 and 2.57×10^-3,both of which were far less than 1,indicating that dietary risk was acceptable.