Rice straw is one of the most widely used cattle feed in Korea. MRLs of pesticides in rice straw feed have been set up 7 pesticides- etofenprox, tricyclazole, diazinon, edifenphos, propiconazole, carbaryl and carbofuran in 2010. However among then, MRLs of four kinds of pesticide, edifenphos, propiconazole, carbaryl and carbofuran, was set up in accordance with the MRLs of foreign and the other 3 pesticides were set through the risk assessment process, were set not properly through the risk assessment proceed.
In this study, the MRLs of pesticides in rice straw were reset according to the FAO and OECD guidelines for the setting of the MRLs of pesticide in food and feed. The proposed MRLs in rice straw were carried out using pesticide residue data of rice trials(in Korea). The MRL proposal in Korea for rice straw were etofenprox 30, tricyclazole 25, edifenphos 20, carbaryl 10, diazinon 5, propiconazole 5 and carbofuran 4 mg/kg. Carbofuran was not detected in rice straw on GAP condition, so MRL of carbofuran in rice straw was not necessary. The estimated MRL(Maximum Residue Level) in livestock products was carried out using proposed MRLs of rice straw and livestock feeding studies. Diazinon, carbaryl and propicoanzole were not detected in the treated livestock. The estimated MRLs in cattle products were etofenprox was 2.85 mg/kg in fat, tricyclazole was 0.41 mg/kg in liver and edifenphos was 0.014 mg/kg in liver. The TMDI of etofenprox, tricyclazole and edifenphos from the intake of cattle by-product were 0.3037, 0.0262, 0.0149% of the each ADI, respectively. Therefore, the proposed MRLs of 6 pesticide were suitable for the tolerance for pesticide residues in rice straw in Korea. Also I suggested the proper risk assessment procedure of rice straw for the future establishment of MRLs.
Second studies were monitoring of pesticide residues in rice straw and risk assessment of pesticide residues in cattle product. A total of 18 rice straw samples were collected for monitoring from 6 provinces in Korea in 2010. In this monitoring, only 3-keto carbofuran was detected in 1 sample and concentration level of this sample was limit of quantitation(LOQ).
For the consumer risk assessment of pesticide residues in cattle product from intake of rice straw, I used tricyclazole and edifenphos residue data in rice straw of this study and reported Rural Decelopment Administration for 1998, 1999, 2001 monitoring programme, National Products Quality Management Service for 2009 monitoring programme. The exposures of tricyclazole and edifenphos for Korean consumer were 0.034%, 0.0007% of ADI at the 99%th percentile respectively.