CAS RN:333-41-5

Toxicity Summary

IDENTIFICATION: Diazinon is a clear colorless liquid with a faint ester-like odor. Diazinon is soluble in most organic solvents. It is stable in neutral media, but is slowly hydrolyzed in alkaline media and more rapidly in acid media. Diazinon is a contact organophosphorus insecticide with a wide range of insecticidal activity. It is also available in mixed formulations with other insecticides. Another major use is as a drug in veterinary medicine. HUMAN EXPOSURE: Environmental levels of diazinon are generally low. The routes of exposure for the general population are inhalational and dietary. Exposure through water is negligible. Occupational exposure is primarily dermal. Several cases of accidental or suicidal poisoning by diazinon hae been reported, some of which were fatal. In some of these the cholinergic syndrome may have been more severe than expected because of the presence of highly toxic impurities such as TEPP. In certain cases, acute reversible pancreatitis was associated with a severe cholinergic syndrome. Reported cases of poisoning after occupational exposure have always been associated with the presence of impurities. ANIMAL STUDIES: The acute oral, dermal and inhalational toxicity is low. Short-term and long-term studies in mice, rats, rabbits, dogs and monkeys have shown that the only effect of concern is dose-related inhibition of acetyl cholinesterase activity. Diazinon is slightly irritant to rabbit skin but not to the eye. Diazinon is not a dermal sensitizer. Reproductive and developmental studies have revealed no evidence of embryotoxic or teratogenic potential. There was no effect on reproductive performance at dose levels that were not toxic to the parent animals. Mutagenicity studies with various end-points in vivo and in vitro gave no evidence of a mutagenic potential. There is no evidence of carinogenicity in rats or mice. In the dog and guinea-pig, diazinon has been reported to cause acute pancreatitis; this is considered to be a species-specific effect. Diazinon may be absorbed from the gastrointestinal tract, through the intact skin and following inhalation. Diazinon is oxidized by microsomal enzymes to cholinesterase inhibiting metabolites such as diazoxon, hydroxydiazoxon and hydroxydiazinon.
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