Outline guide for performance of field studies to establish safe reentry intervals for organophosphate pesticides

Abstract

Residues of cholinesterase-inhibiting pesticides on the foliage of certain crops can pose a hazard to farm workers whose work brings them into prolonged and intimate contact with the foliage. Poisoning episodes caused by residue exposure of this type have occurred on numerous occasions since 1949 (KAHN 1976). Although incidents have been reported in tobacco fields in the Southeast and apple orchards in Washington the great majority of these episodes have been in California. Most observers attribute this predilection for one state to dry fields and rainless summers with resulting heavy dust deposits on the foliage. The dusty matrix enhances the persistence of organophosphate residues and the most toxic degradation products of the thiophosphates, their oxons.