Problem of studying the toxicity of indole

Inhalation of indole vapors in a concentration of 9.0 to 10.0 mg/cu m for two to three hours causes no substantial changes in the organism of mice, rats and rabbits. After intravenous injection of rabbits with 10.0 mg of an alkaline solution of indole the latter is quickly rendered harmless and expelled from the organism. The threshold for perception of the unpleasant odor of indole is 0.45 mg/cu m. Inhaling the indole vapors in the concentration of more than 1.0 mg/cu m may lead to negative subjective sensations: headache, nausea.