Predicted and Observed Residues of Bioresmethrin, Carbaryl, Fenitrothion, d-Fenothrin, Methacrifos and Pirimiphos-Methyl on Rice and Barley after Storage, and Losses of These Insecticides during Processing

Abstract

Levels of residues of bioresmethrin, carbaryl, fenitrothion, d-fenothrin, methacrifos and pirimiphos-methyl were determined on unhusked rice, husked rice, polished rice and barley over a storage period of six months. The observed levels were close to levels predicted from use of a model which relates rate of loss of residue levels to a rate constant and only two variables, temperature and equilibrium relative humidity. The fate of residues was determined during processing of rice and barley. Data on losses during processing are also given for dichlorvos on rice and malathion on barley. After the milling process, residues of all protectants applied to unhusked rice were concentrated in the husks and bran. The proportion of protectant lost during cooking of rice varied between protectants, and was especially great for dichlorvos, methacrifos and carbaryl. All protectants were extensively degraded during commercial malting of barley and the loss of methacrifos was especially pronounced. © 1980, Pesticide Science Society of Japan. All rights reserved.