Residue Behavior And Dietary Risk Assessment Of Cyazofamid In Two Agricultural Products

Cyazofamid has been widely used to control diseases during the growth of tomato and grape,such as tomato late blight(Phytophthora infestans)and grape downy mildew(Plasmopara viti-cola).Cyazofamid rapidly decomposes into4-chloro-5-p-tolylimidazole-2-carbonitrile(CCIM)after field application,and CCIM was more easily absorbed by crops.CCIM was more toxic than cyazofamid,and its residue may lead to higher risk from dietary intake in agricultural products.Therefore,it was of great significance to study the residue and degradation dynamics of cyazofamid and CCIM after application in the field,and the change of pesticide residues in agricultural products processing.Tomato and grape were selected as the main objects in this study.The residue characteristics of cyazofamid and CCIM in the field and the change rule of pesticide residues during processing were studied systematically.The main conclusions were presented as follows.The residue and disspation dynamics of cyazofamid and its main metabolite CCIM in tomato and grape were investigated by Qu ECh ERS-high performance liquid chromatography-tandem mass spectrometry(Qu ECh ERS-HPLC-MS/MS)method.Field experiments were conducted in ten fields for one years.At three levels of 0.005 to 2 mg/kg(tomato)or 0.005 to 1 mg/kg(grape),the results showed that the average recoveries of the two compounds in tomato and grape were 86% ~ 102% and 85% ~ 101%,respectively,with RSDs less than 10%.The quantitative limits(LOQ)for tomato and grape samples were both0.005 mg/kg,which met the requirement of max residue limits of cyazofamid.The dissipation dynamics of cyazofamid in tomato and grape matrices fitted the first order kinetic equation,and the half-lives in tomato and grape were 4.9 ~ 10.3 d and 8.6 ~ 11.9 d,respectively.The final residue data indicated that the cyazofamid residue in tomato and grape were less than the maximum residue limit established by China(tomato: 2 mg/kg;grape: 1 mg/kg).The home canning of tomato paste: The behaviors of home canning on residue levels of cyazofamid and its metabolite CCIM in tomato were investigated.The results showed thatwashing and peeling had a notable effect on the removal of cyazofamid and CCIM,the reduce rates of cyazofamid and CCIM were 92.3% and 75.2%,including washing,whereas homogenization,simmering and sterilization process had no obvious effects on the removal of cyazofamid and CCIM residues.After homogenization,the residual amounts of cyazofamid and CCIM in tomato seeds were below the limit of quantification(5 ?g/kg),which was mainly present in the tomato puree.The part of the water was lost after simmering,which leaded to an increase in the amount of cyazofamid and CCIM in tomato paste.The mean reduction of cyazofamid in tomato samples after sterilisation was 57.2%,while for CCIM it was 16.3%.The results displayed that the overall process processing factors(PFs)of cyazofamid and CCIM during tomato paste processing were 0.014 and 0.070,respectively.Wine processing: The fate of cyazofamid and its main metabolite CCIM were evaluated during wine-making process in detail.Results showed that residues of cyazofamid and CCIM decreased significantly in wine processing,and the removal efficiency was 78.0% ~ 95.0% in peeling process and 88.0% ~ 95.4% in fermentation process,and the processing factors were0.025 ~ 0.187 and 0.046 ~ 0.120,respectively.The dissipation of cyazofamid in the fermentation process followed the first-order of kinetics,and the half-life of cyazofamid was46.2 ~ 63.0 h,whereas,the residues of CCIM,in the three treatments,decreased with time elapse.During red wine and white wine production,the processing factors were all less than one in different processing processes,and the PFs ranges of cyazofamid and CCIM were0.002 ~ 0.029 and 0.046 ~ 0.079 in three treatments in the overall process.The National Estimated Daily Intake(NEDI)was applied to assess the dietary exposure of pesticide residues in tomato and grape fruits and processed agricultural products.Results showed that the dietary exposure risk index of cyazofamid in tomato and grape fruits were less than 100%,and dietary exposure risk was at an acceptable level.The level of pesticide exposure was different for different age and gender groups.In general,dietary exposure gradually decreased with increasing age.Among them,children(2 ~ 4 years old)had the highest dietary exposure,and females in the same age group had slightly higher dietary exposure than men.The effects of processing factors on pesticide residues were excluded,anduncorrected Supervised Trials Median Residue(STMR)values were used for risk assessment of dietary exposure,which resulted in significantly higher levels of pesticide exposure.The risk assessment results of pesticide dietary exposure in processed agricultural products indicated that the dietary exposure risk of tomato paste and wine was much lower than that of the initial agricultural products after the processing step by step.The more processing steps,the smaller the risk of pesticide residues in its agricultural products.The results of this paper have significance meaning for the scientific use of pesticides,the establishment of processing factor databases,and the assessment of dietary exposure risks.