Residue Digestion And Dietary Risk Assessment Of Pyraclostrobin In Different Types Of Vegetables

This paper established the residue detection method of pyraclostrobin in fo ur vegetables which are summer squash,pakchoi,canola,and taro.In order to evaluate the safety of the pesticide on leaf-vegetable,tuber-vegetable and fruitvegetable,field trial were conducted in six provinces for a year.Results of di ssipation dynamics and terminal residue would contribute to rationally useing a nd controling of pyraclostrobin i,as well as development its maximum residue l imits.The main conclusions are as follows:(1)The method for determination of pyraclostrobin in squash,pakchoi,can ola,and steamed bread was established.The average recoveries of pyraclostrobi n in the samples were between 79% and 98% with relative standard deviations between 2.9% and 11.5%.The method meets the requirements of pesticide resi due analysis methods and can be used in the quality monitoring department of agricultural products in China.(2)The relationship between the spraying concentration of pyraclostrobin pesticides and spraying times and the amount of pyraclostrobin residues was investigated.The study found that the final residue of pyraclostrobin in Chinese cabbage,oiled wheat dish and steamed bread increased with the increase of application concentration and the number of application times,and it was not very obvious in zucchini.(3)The dynamics and residue of pyraclostrobin on four different crops were studied.The results of the field experiment in Changsha exposed land show that the half-lives of pyraclostrobin on Chinese cabbage,oiled wheat dish,steamed bread plant and summer squash were 4.2d,3.9d,8.3d and 2.3d,respectively.Field trials in the Shijiazhuang greenhouse showed that the half-lives of pyraclostrobin on Chinese cabbage,oil-vegetables,taro plants,and squash were 6.1d,8.2d,10.6d,and 1.6d,respectively.According to the statistical analysis of the residual data,the residues of pyraclostrobin on oil-vegetable and Chinese cabbage are relatively high,while the oil-and-vegetable and bok choy are both leaf vegetables,followed by zucchini,are fruit and vegetable,and have the lowest steamed bread and are tubers.The residue of pyraclostrobin on these three types of vegetables was obtained as leaf vegetables>fruit vegetables>tubers.(4)The effects of crop type,location and planting environment on the degradation of pyraclostrobin were studied.The experimental results showed that pyraclostrobin residues in leaf vegetables were significantly higher than those in tubers and fruit vegetables;the residues of pyraclostrobin in steamed buns were higher,but no pyraclostrobin was detected in taro tubers.Residues.(5)Long-term dietary risk assessment of pyraclostrobin.The median residual value(STMR)of Pyraclostrobin on Chinese cabbage was 1.660 mg/kg,4.006 mg/kg on seaweed,<0.02 mg/kg on sea bream and 0.073 on zucchini.Mg/kg,combined with the registration of pesticides in China and the per capita dietary structure of residents in China,the national daily intake of pyraclostrobin in the general population is 0.51 mg,accounting for 27.6% of the daily allowable intake.The %ADI of Pyraclostrobin is less than 100%.It is considered that the content of pyraclostrobin in Chinese cabbage,oiled mustard,taro,and zucchini will not cause unacceptable risks to the health of the population,and meets the requirements of dietary safety risk assessment.