Organophosphate Pesticides


Organophosphate pesticides are esters of phosphoric acid. Organophosphate pesticides are powerful poisons and kill the pests by means of acetylcholinesterase blockage. This results in nervous and respiratory injuries leading to killing of insects. However, organophosphate insecticides are also dangerous for humans.

Malathion pesticide moleculeOrganophosphate insect killers are the most poisonous of all pesticides. Fortunately, they are rather unstable and therefore are decomposed fairly fast in the environmental conditions. More than 100 of organophosphate pesticides are offered for commercial application. The majority of organophosphate pesticides are insecticides. Some of them are also used as herbicides and fungicides.

Products containing organophosphate pesticides

The main products used in agriculture are Malathion, methyl parathion, fenitrothion, diazinon, chlorpyrifos, tetrachlorvinphos, dichlorvos, phosmet, and azinphos methyl. Organophosphate pesticides are applied as contact and systemic insecticides in agriculture. They also suppress household pests. Organophosphate insecticides are as well used against lice in humans and some ectoparasites in animals.

Mechanism of action of organophosphate pesticides

These pesticides inhibit the enzymes that take part in the conduction of nerve impulses. Nerve impulses are transmitted in the form of acetylcholine at the junctions between the neurons and muscles. This acetylcholine neurotransmitter is inactivated by cholinesterase. Exposure to organophosphate pesticides results in cholinesterase block and accumulation of acetylcholine. This disturbs correct transmission of impulses at the nerve and muscle endings.

Organophosphate pesticides and health

Organophosphate insecticides can invade the body through skin, lungs, or digestive system. The intoxication with organophosphate insect killers results in various signs and symptoms reflecting the affection of numerous organs and systems. Organophosphates provoke acute intoxication in humans with general weakness, tremors, headaches, concentration disturbances, abdominal cramps, nausea, vomiting, diarrhea, excessive perspiration, salivation and lachrymation. In serious cases, respiratory failure and even death may occur. Several weeks after exposure, doctors may diagnose severe neuropathy with sensations of burning and tingling passing to the paralysis of the lower extremities.

Delayed consequences of organophosphate poisoning

Exposure may lead to cumulative intoxication with unfavorable effects on the nervous system. Researchers find psychological and behavioral changes in humans after the exposure to the organophosphate insecticides. Agricultural organophosphate insecticides may provoke depression and even suicide attempts.

Organophosphate insecticides are associated with short-sightedness and Saku disease. Saku disease is characterized by the optic neuropathy and visual disturbances such as myopia, astigmatism, reduced vision, narrowing of the visual fields, degeneration of ciliary muscle and retina.

Doctors also observed heart effects associated with professional exposure to organophosphate insect killers such as slowing of the heart rate, reduced cardiac output, myocarditis, and heart attacks.

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