Measurement of sensory irritation of the skin

The sensory reaction to contact with chemical irritants has not been extensively studied. This neglect has been caused partly by a lack of understanding of the physiological basis of subjective irritation, and partly by inadequate methods of perceptual measurement. This article begins with a brief overview of the neurophysiology of cutaneous chemoreception (chemesthesis), and continues with a discussion of numerous sensory, physical, and perceptual factors that can affect the sensitivity to irritants. Then, guidelines for conducting perceptual measurements of subjective irritation that take these factors into account are offered. An alternative approach to direct chemosensory measurement also is proposed that relies on the fact that many of the cutaneous receptors that are sensitive to chemicals also are sensitive to temperature and/or mechanical stimulation (pain or itch). It is suggested that thermal and mechanical sensitivity might prove useful as measures of the severity of acute sensory irritation and as indicators of subclinical sensitization by environmental irritants.