[Toxicology of acetonitrile]

Acetonitrile is a high-polarity organic solvent widely used in various chemical industries and laboratories. It was once used in consumer goods such as cosmetics. Acetonitrile is readily absorbed through the skin, by inhalation and by ingestion, and acute poisoning and even fatal effects are possible via these routes. The oral LD50 of acetonitrile in mice, which are one of the most susceptible animals to acetonitrile, is 170-520 mg/kg, and LC50 is about 2,700 ppm after one hour of inhalation. The toxic effects of acetonitrile are attributable to the metabolic release of cyanide, but the symptoms of poisoning may be delayed a few hours or more due to slow hepatic metabolism. No information is available yet about the toxicity of intact molecules of acetonitrile or formaldehyde which may be formed together with cyanide in the body. In subacute toxicity experiments in animals, slight changes in hemograms, histopathologic changes in the lung, increase in thyroid function, and other changes have been reported. No information is available about the accumulation of acetonitrile or its metabolites in tissues following repeated administrations, although formaldehyde is known to have high reactivity with macromolecules. No study has yet been done on the chronic toxicity or carcinogenicity of acetonitrile after prolonged administration. Acetonitrile is not mutagenic in the standard test using Salmonella typhimurium. Inhalation of acetonitrile by pregnant animals may produce malformations in the offspring such as axial skeletal disorders at maternally toxic levels. Education and information about the toxicity and regulations on the marketing of acetonitrile are of great importance for the safe use of this material. Further studies and information are needed on the chronic effects of acetonitrile, especially its carcinogenic potency, to human beings.