| Diazinon is an organophosphate chemical pesticide, O,O-diethyl-O-(2-isopropyl-6-methy-4-pyrimidinyl)phosphorothioate. It is designed to kill garden and home insect pests, and is remarkably unspecific about its target organism (i.e. it will kill just about anything except most plants).
Diazinon combines chemically with the acetylcholinesterase enzyme and deactivates it. This enzyme is essential for control of nerve impulse transmission. Loss of acetylcholinesterase allows the accumulation of acetylcholine, the substance secreted by nerves that activates muscles, glands, and other nerves. It is this nerve inactivation that causes the death of the target organism.
Pests intended to be controlled by diazinon include cutworms, weevils, boring beetles, root maggots, ants, termites, silverfish, and countless other insect pests. In practice, it will kill all of these as well as spiders, worms, slugs, and beneficial arthropods. Birds feeding on areas treated with diazinon can be killed by exposure. As few as five granules of diazinon can kill most small birds.
Diazinon is relatively unstable in the environment, and it degrades to form many compounds. Some of the compounds identified by the EPA as relevant to environmental impact include:
oxy-pyrimidine, referred to as G-27550, 2-isopropy-6-methyl-4-pyrimidinol
De-methyl oxy-pyrimidine: 2-ethyl-4-hydroxy-6-methyl pyrimidine
GS-31144: 2-(1-hydroxy-1-methyl ethyl)-4-hydroxy-6-methyl pyrimidine
diazoxon: O,O-diethyl-O-(2-isopropyl-4-methyl-6-pyrimidinyl) phosphonate.
Of these, diazoxon is the most troublesome, having a toxicity of approximately 10,000 times that of diazinon.
The principal signs and symptoms of acute diazinon poisoning are headache, nausea, dizziness, pinpoint pupils, blurred vision, hypersecretion, tightness in chest, difficulty breathing, muscle weakness or twitching, difficulty walking, vomiting, abdominal cramping, and diarrhea.
Contact with diazinon through inhalation of dust or emulsion, ingestion, as well as dermal contact will result in toxicity effects. Many reports of toxicity through residential spraying of diazinon emulsion for household pests have been reported. Some of these incidents have resulted in hospitalization of those affected, as well as many lawsuits. These negative effects on humans, coupled with the deaths of endangered migratory birds feeding on treated areas, have led the US EPA to phase out the use of diazinon for residential and agricultural uses, with a complete ban to be in place by the end of 2003. Many candidates for the Darwin Awards appear in the annals of the EPA's incident reports concerning diazinon, including leaching into hooch manufactured by inmates, and many failed attempted suicides. The funniest such account is an individual who applied concentrated diazinon to his scrotum in an attempt to rid himself of genital lice. The dermal absorption toxicity of diazinon landed him in the hospital with severe nausea, diarrhea, and twitching. Poor stupid man with crabs. | 
