DURING the past 20 years, organophosphorus pesticides have become one of the important groups of pest control agents in agriculture. Parathion, O, O-diethyl-O-p-nitrophenyl thiophosphate, is one of the most commonly used of the organophosphorus insecticides and is probably responsible for more instances of accidental poisoning and death than any other organophosphorus compound.1 Commercially, it is available as dusts, wettable powders, concentrates, and aerosols. It is very slightly soluble in water, and because it is slowly hydrolyzed, a spill or residua may remain hazardous for several weeks or even months.2
Route of entry is through the skin, conjunctiva, by ingestion, and inhalation. The onset of symptoms and signs of toxicity after a single acute exposure varies according to the dose and the route of administration, and the time of death is usually rapid occurring within 30 minutes to 24 hours after contact. Because parathion inactivates cholinesterase enzymes in the