The effects of n-butanol vapour on respiratory rate and tidal volume

Exposure to n-butanol vapour gave rise to a sensory irritation response which was measured by the reflexively induced decrease in respiratory rate in mice according to the American standard method (E981-84). The response reached maximum within the 1st min of exposure. In this period the expected threshold response (RD-0) and the concentration expected to depress the respiratory rate by 50% (RD-50) were extrapolated to be 233 ppm and 11,696 ppm, respectively. The response followed the dynamics of a bimolecular reaction between butanol and the sensory irritant receptor. For concentrations below 3000 ppm, the response faded due to desensitization. However, concentrations above 3000 ppm gave rise to a new decrease in respiratory rate due to activation of lung receptors. Two types of lung receptors, probably J-receptors and stretch receptors, were involved. The sensory irritation response measured by the standard method gave a threshold response which was comparable to that found by electrophysiological experiments in rats. The irritation response in man as well as the maximum allowable concentration in the working environment were adequately predicted from the sensory irritation response in mice.