Ammoniated forage poisoning: acute toxicity of newly identified dialkylimidazoles to inbred mice.

The i.p. acute toxicity of the dialkylimidazoles 1,2-dimethylimidazole, 1,4-dimethylimidazole, 1,5-dimethylimidazole, 2,4-dimethylimidazole and 2-ethyl-4-methylimidazole was investigated in C57B1 female mice, and compared to the toxicity of 4-methylimidazole (4-MI). An approximate median lethal dose protocol was applied designed to obtain a qualitative description of the clinical toxic effects and an estimate of the acute lethal dose with the use of a minimal number of animals. The approximate median lethal dose of the dialkylimidazoles varied from slightly above to 3-times greater than that of 4-MI. 1,4-Dimethylimidazole and 1,5-dimethylimidazole had tremorogenic and convulsive effects qualitatively similar to those of 4-MI. Testing a mixture of alkylimidazoles comparable to the composition found in toxic ammoniated forage or milk did not indicate any synergistic enhancement of the toxicity to mice.