Residual Characteristics of Lambda-cyhalothrin and Deltamethrin in Lettuce

This study was carried out to investigate the residue patterns of two insecticides, lambda-cyhalothrin and deltamethrin, commonly used for lettuce, under greenhouse conditions. The pesticides were sprayed with dilution of recommended and doubled doses onto lettuce. Their detection limits were and mean recoveries at the fortification levels of 0.2 and were from 101.17 to 104.25 and from 99.70 to 103.77%, respectively. The pesticides were gradually decreased in lettuce with time. Biological half-lives of lambda-cyhalothrin and deltamethrin were 1.7 and 1.4 days at the recommended dose and 1.8 and 1.4 days at the doubled dose, respectively. Initial residue amounts of lambda-cyhalothrin and deltamethrin at the recommended and doubled doses exceeded their MRLs. However, the residue levels of the pesticides in the crop sampled at harvest were less than their MRLs. The ratios of the estimated daily intake (EDI) to acceptable daily intake (ADI) by intake the crop harvested 10 days after spraying were less than 1% of their ADIs.