Estimation of maximum residue level and dietary risk assessment of cyfluthrin in tomato (Lycopersicon esculentum Mill.) var. del Monte in the Philippines

Cyfluthrin, cyano (4-fluoro-3-phenoxyphenyl) methyldichloro-ethenyl-2, 2-dimethyl cyclopropanecarboxylate, is a relatively new synthetic pyrethroid insecticide popularly used in tomato to control tomato fruitworm. At present, there is no existing or proposed maximum residue level in the Philippines for cyfluthrin in tomato. A maximum residue level (MRL) of cyfluthrin in tomato was estimated to provide data on the residue of cyfluthrin under the country's climatic conditions and farming practices. The study on the decline of the cyfluthrin residue in tomato field located in Brgy. [village] Gagalot, Majayjay, Laguna [Philippines] during a dry season (Jan-Apr 2001) using the following application rates: recommended rate (25 g a.i/ha applied once a week); twice the recommended rate (50 g a.i/ha applied once a week); and farmers' practice (50 g a.i/ha applied twice a week). Additional supervised trials were also attempted in various sites in Laguna to satisfy the Food and Agriculture Organization's guidelines for the estimation MRL. However, the high incidence of bacterial wilt and the frequent strong rainfalls made the attempts futile. In this study, estimated local MRL of cyfluthrin in tomato was 0.1 mg/kg. Application of twice the recommended rate and farmers' practice resulted to higher residue levels of cyfluthrin in harvested tomato in all the dates of harvest compared to that using the recommended rate. The half-life of cyfluthrin in tomato based on the recommended rate, twice the recommended rate and farmers' practice were calculated to be 10, 8, and 6 days, respectively. Assessment of risk exposure of Filipinos to cyfluthrin in the diet indicated no considerable hazards based on the estimated local MRL gave 1% consumption of the 0.02 mg/kg body weight as the allowable daily intake of cyfluthrin. The impact of various household practices in the cyfluthrin residue in tomato gave the following percent reduction: washing by soaking in water with gentle hand rubbing (67.86%); cooked without lid (47.09%); washing using flowing water followed by cooking (40.10%); washing using flowing water (37.43%); cooking with lid (36.59%); and pressurized cooking (5.22%)