Greenhouse Cucumber Organophosphorus Pesticide Risk Assessment In The Study

The whole control from farm to dining table of farm products must be based on scientific risk analysis. The dynamics of organophosphorus pesticides residues, transferring in cucumber protected cultivation and processing was studied. With the results of chlorpyrifos and dichrovos used in protected cultivation trial experiment, processing residues and dietary investigation of the population of Jiangsu, the exposure and edible safety of raw cucumber was assessed and analyzed. The main conclusions of this study are as the following:The first, A method to identify and quantify chlorpyrifos and dichrovos separately and five organophosphorus pesticides simultaneously in cucumber was developed using the liquid chromatography-tandem triple quadrupole mass spectrometric (LC-MS/MS). Chlorpyrifos and dichlorvos was extracted by acetone:hexane (1:1) and acetonitrile separately, the result was fine. The latter sample was extracted by acetone and cleaned up with florisil. The separation was performed on a ZORBAX SB-C18(5μm×2.1mm×150mm) with the gradient elution of methanol-water with0.1%formic acid as mobile phase. Sample was detected by multiple reaction monitoring (MRM) with electric spray ionization (positive). The result showed that satisfactory linear results have been got with r2≥0.998. The limits of quantity (LOQ) of dimethoate and dichlorvos was0.002mg/kg, the limits of quantitation (LOQ) of trichlorfon, fenitrothin and chlorpyrifos was0.01mg/kg, recoveries of the analyte, depending on the matrices and spiked concentration, ranged from71%to105%with relative standard deviations(RSD)≤3.6%. This simple, rapid and sensitive method can applied to supplying reliable data for the study of the risk assessment of raw vegetables.Secondly, the trails of safety interval period and the dynamics regulation of chlorpyrifos and dichlorvos pesticides in protected cucumber were studied. Simultaneously truer organophsphorous pesticides data of protected cultivation was gotten. The result showed that harvest interval of chlorpyrifos and dichlorvos in cucumber was both one day if by the MRL of china in vegetables. And found that the degradation rate of chlorpyrifos under protected cultivation was lower than that under conventional cultivation. The half-life period of chlorpyrifos in protected cultivation was longer than spring protected cultivation. The degradation rate of dichlorvos under protected cultivation was slower than that under conventional cultivation.The third, the reduction method of five organophosphorus pesticides include trichlorfon, dimethoate, dichlorvos, fenitrithin and chlorpyrifos in cucumber was imitated under lab. The operation of pesticide reduction included tap water, sodium carbonate, sodium hydrogen carbonate, wash rice water, acetic acid, sodium chloride, ultrasonic cleaning and store et.al. The result showed that dichlorvos was influenced strongly by temperature. The pesticide residue was dropped down to lower level by high temperature storage and warm water with40℃. The optimum reduction method foe trichlorfon and dimethoate was sodium carbonate, the highest removal rate of dimethoate was80.6%. The wash rice water soaking is the optimum reduction method for chlorpyrifos and fenitrothin, the removal rate was97.1%and87.4%separately. Therefore, it is effective for the reduction of the five organphsphorus pesticides by home simple handles.Finally, the population exposure and potential chronic and acute hazard of chlorpyrifos and dichlorvos in cucumber of Jiangsu area were assessed based on the concentration of pesticide residues of one day safety interval, the information from other literature and the lowest and the highest removal rate (processing factor) of chlorpyrifos and dichlorvos that were processed by kinds of methods. Dietary exposure evaluation model (DEEM) was applied to calculate the population’s daily intake of chlorpyrifos and dichlorvos. The percentage of RfD and margin of exposure were used to evaluate the chronic and acute hazard. The result showed that the risk of chlorpyrifos concern for entire population is higher than dichlorvos. The chronic risk of chlorpyrifos and dichlorvos concern for children, female teenagers and men over60years old is higher, the acute risk concern for male teenagers, adults and olds was serious than chronic risk. From teenagers to olds, the difference of chronic risk is small between males and females.When we used the minimum removal rate (processing factor) and didn’t pesticide according to the recommended dosage, the girls under6years old faced high chronic risk about chlorpyrifos. Therefore, in order to address these risks and ensure the safety of intaking raw cucumber, extended interval of harvest and done the washing preparation of cucumber well before eating it will be needed.