Acute Inhalation Toxicology of Volatile Hydrocarbons

Abstract

Mice were exposed to various concentrations of volatile hydrocarbons and measurements made of respiratory rate, depth and configuration while the animals were inhaling the agent. Mice were exposed to the volatile hydrocarbons n-pentane, n-hexane, n-heptane or iso-octane. Additional mice were also exposed to the anesthetics diethyl ether or methoxyflurane for comparative purposes. The concentrations used were 1,000; 2,000; 4,000; 8,000; 16,000; 32,000; 64,000 and 128,000 ppm. Exposures were for five minutes. The volatile hydrocarbons from pentane to heptane produced anesthesia and were irritating to the respiratory system. The irritation increased in intensity with the length of the carbon chain. Iso-octane was highly irritating even at the lower concentrations. As the number of carbons increased the anesthetic properties became less and the concentration needed to produce narcosis and respiratory arrest was lower. When respiratory arrest occurred with all off the agents except iso-octane it took place at the end of inspiration. With iso-octane it occurred in the expiratory phase during prolonged expiration. Respiratory arrest was reversible with diethyl ether but was not with methoxyflurane or the volatile hydrocarbons. This technique of recording respiratory rate depth and configuration can be useful in evaluating the toxic effects of inhalable agents.