Evaluating the human response to sensory irritation: implications for setting occupational exposure limits.

Although animal models of sensory irritation have led to the development of useful assays for evaluating the potency of chemical irritants, the importance of conducting human exposure studies to model and understand the human response to sensory irritants cannot be minimized. In recent years a series of tests have been developed for humans that can be safely conducted and that can provide excellent data on which to base occupational exposure limits. This article delineates the major issues involved in the evaluations of sensory irritation in humans. Among these issues are the differences between odor and irritation, irritation and slight toxicity, adaptation and habituation, as well as personal expectation about discomfort and the reported irritation. The article also describes psychophysiological and electrophysiological methods for assessing sensory irritation. Some of the possible confounders that can influence the results of human tests involving sensory irritants are addressed.