Diazinon is an organophosphate synthesized from thiophosphoric acid as a colorless and odorless oil-like liquid, but may also be further processed to produce a granular form. It is known by many other names, including spectracide, dipofene, basudin, and its lengthy chemical name of O,O-Diethyl-O-(2-isopropyl-6-methyl-pyrimidine-4-yl). However, most people immediately recognize this substance as one of the best-known organophosphorus pesticides used to control cockroaches, fleas, and ants. When formulated for home and garden use, diazinon insecticide spray represents a one to five percent concentration, while industrial preparations typically contain 85-90 percent diazinon.
Like many other organophosphates, diazinon is a potent neurotoxin. Specifically, it permanently suppresses the activity of acetylcholinesterase, an enzyme which is necessary for nerve function. The mechanism behind this action involves the agent’s phosphorus atom binding to the enzyme site. Since the role of acetylcholinesterase is to degrade the neurotransmitter acetylcholine, an excessive amount is left to concentrate in the synaptic cleft where it can no longer reach neurotransmitter receptors. This activity results in paralysis and, ultimately, death.
The Environmental Protection Agency (EPA) took action in the late 1980s to stop the use of this chemical to treat the turf on golf courses because of its detrimental effect on bird populations. In December 2004, the sale of any diazinon-based insecticide or pesticide intended for residential lawn, garden, or indoor application was banned. However, it is not unlawful for consumers to use any product that may have been stored prior to the ban being initiated, as long as protocols for its handling and disposal are met. In addition, the EPA continues to allow the use of diazinon for agricultural use.
In terms of environmental impact, diazinon is considered non-systemic. It does not persist in the environment since it naturally degrades into other chemicals relatively quickly. In fact, the substance has a half live of only two to six weeks. However, although this substance may not bioconcetrate in the food chain, it can be transported through the soil by runoff and contaminate groundwater.
Obviously, ingestion of diazinon should be avoided. However, it can readily permeate the skin, from which it can enter the bloodstream and target the nervous system. For this reason, great care should be taken when handling this substance. Statistically, the incidence of accidental poisoning in humans is relatively low, but exposure to very high levels has proven fatal. Signs of mild toxicity include impaired vision with constricted pupils, dizziness, and muscle weakness, while severe toxicity is indicated by vomiting, slow pulse, labored breathing, and coma.