Residue And Dietary Risk Assessment Of Pyridaben In Brassica Oleracea And Soil

An analytical method for determination of pyridaben residue in brassica oleracea and soil was developed in this study. The field trials were conducted at Guangzhou, Hubei and Beijing during year2011to2012to study the dynamic dissipation and terminal residue of pyridaben. Meanwhile the dietary risk assessment of pyridaben on brassica oleracea was also evaluated. The results are as follows:(1) Acetonitrile was used as extraction and Liquid chromatography-thiple quadrupole mass spectometer was used to analysis the residues of pyridaben in brassica oleracea and soil samples. Results showed that when the spiked levels were0.01、0.1、0.5mg/kg, the average recoveries were from90.29%～95.00in brassica oleracea, and87.85%～98.22%in soil, respectively.(2) The dissipation dynamic of pyridaben in brassica oleracea and soil of Guangzhou, Wuhan and Beijing followed the first-order kinetics. The half lives of pyridaben in brassica oleracea and soil of Guangzhou, Wuhan and Beijing were2.5-5.3d and2.6～23.1d respectively.(3)Under the recommended and1.5times recommended dosage, sprayed3or4time, the terminal residues of pyridaben in brassica oleracea was0.01-1.00mg/kg3day,5day and7day after application. The values were all below the maximum residue limits for pesticides (MRL). According to the results, when40%pyridabne (WP) was used under the recommend dosage, which is90～135g a.i/hm2, and spray3times with spraying interval of7days, the residue of pyridaben in brassica oleracea was safe for human being when the pre-harvest interval (PHI) was3days.(4) The results of risk assessment showed that national estimated daily intakes (NEDI) of pyridaben were6.37～13.81ug·kg-1bw·d-1for different crowds, the percent ratio to acceptable daily intake (ADI) was6.37%-13.81%. Theoretical maximum daily intakes (TMDI) of pyridaben were9.09～19.70ug·kg-1bw·d-1, the consumer protection level (CPL) of pyridaben MRL were1.10-0.51.