THERE are many reports of accidental poisonings with the long-acting anticholinesterase alkyl phosphate insecticides.1-4 Malathion, the O,O-dimethyldithiophosphate of diethylmercaptosuccinate, has been less involved in such accidents.5-10 Experimental and clinical studies indicate that malathion is less toxic to mammals, including man, while it retains significant potency as an insecticide.11-17 This is because certain enzymes, ali-esterases, in the sera of experimental animals and in the livers of experimental animals and man, are capable of hydrolyzing malathion and converting it to an inactive form.18 This effect seems to be mainly responsible for malathion's reduced toxicity since inactivating the ali-esterases with such compounds as triorthotolyl-& phosphate greatly increases malathion's toxicity to experimental animals.18
Wide experience gained with the earlier representatives of this class of insecticides, such as parathion, prompted the development of safety measures with respect to their utilization. Nevertheless, individuals occasionally ingest massive quantities of malathion and develop