Risk Assessment Of Three Pesticides In Mint And Residue Transfer During Processing

The pesticides registered in crops which can use both as food and medicine are very few due to its small planting area or low economic return to the producers. However the pesticide application is unavoidable to prevent the disease or pest damage in agricultural practices. Thus serious pesticide residue problem on these crops was caused because of the improper use of unregistered pesticides..Mint is one of the medicinal and edible crops.Currently,there is no pesticide registered in mint. In this study, a multi-residue analytical methods of33kinds of pesticides in mint was established,and based on pest and disease control on mint in practical production, triadimefon, fenvalerate, fenitrothion were selected to conduct field trials in four regions of China. Dietary intake risk assessment of those pesticides in mint was evaluated,and meanwhile,the behavior of pesticide residue during mint processing was also studied.The results of the study could give a reference of Chinese government to set MRL of pesticides used in mint, and to investigate a feasible way to extrapolate the pesticide application between minor crops and major crops. The main results are as follows.1. An analytical method was developed to determine33pesticides residues in mint. The samples were extracted with cyclohexane/ethyl acetate based on ultrasonic extraction, purified by amino-graphite carbon solid phase extraction (SPE) and detedcted by GC-ECD. Results showed that recoveries of33pesticide residues in mint ranged from72.1to113.9%with relative standard deviations (RSDs) less than19.2%. Limits of detection (LODs) and limits of quantification (LOQs) were0.1-80μg/kg and0.5～200μg/kg, respectively.2. The safety evaluation was conducted for application of triadimefon, fenvalerate and fenitrothion on mint according to the GAP used in other crop whose pest or disease was the same as in mint. The field trials of triadimefon, fenvalerate, fenitrothion on mint were conducted in four regions including Beijing, Hebei, Jiangxi and Shandong in2013. Results showed that the degradation of three pesticides fitted for the first order kinetic equation. The dissipation of fenvalerate in Hebei and Beijing was faster than that in Jiangxi and Shandong. The dissipation of fenitrothion and triadimefon were similar and the half-life of fenitrothion was1.0～2.4day and for triadimefon was0.9～3.9day. The residue levels increased with the increasing of pesticide application dosage. When the harvest interval was20days, the maximum residues of triadimefon, fenvalerate and fenitrothion was up to1.51mg/kg,0.29mg/kg and0.60mg/kg, respectively. The chronic dietary intake risk quotient of, fenvalerate and fenitrothion exposure on mint was16.03%,73.46%and311.43%, and all three pesticides had no short-term dietary intake of pesticide risk, thus it can be concluded that triadimefon and fenvalerate are safe when used on mint with experiment dosage,however, fenitrothion is not suggested to be used on mint considering the high chronic dietary intake risk quotient.3. The behavior and risk assessment of pesticides in mint during processing were investigated. Results showed the transfer rate of triadimefon, fenvalerate and fenitrothion during immersion processing were0.47,0.46and0.44, respectively. Most of pesticide residues transferred to air or degraded during decoction processing. The transfer rate of triadimefon, fenvalerate and fenitrothion during decoction processing were0.21,0.10and0.08, respectively. The transfer rate of triadimefon, fenvalerate and fenitrothion during frying and cooking were0.41,0.25and0.10, respectively. The pesticide residues were increased during dry processing because of the lossing of moisture. The transfer rate of triadimefon, fenvalerate and fenitrothion during dry processing were1.97,1.51and3.66, respectively. The differences of Mint dietary risk assessment after processing comparing with the agricultural commodities were not significant except the application of triadimefon during mint drying had a certain acute risk to general people.The results of the risk assessment showed that except fenitrothion, the influences of triadimefon and fenvalerate on mint, mint tea, fried and cooked mint and dried mint are acceptable for general population.