Odor, irritation and perception of health risk

OBJECTIVES: Understanding the potential for volatile chemicals to elicit chemosensory irritation in the upper respiratory tract is critical to setting occupational exposure limits that are protective of comfort and well-being for the majority of workers. However, the determination of irritant potency for any volatile chemical has been limited by the lack of reliable and non-invasive assays for studying sensory irritation in humans and a failure to appreciate the many non-sensory factors that can influence the reactions to an odor or an irritant in the workplace. METHODS: This paper reviews the issues involved in distinguishing and measuring sensations of odor and irritation from volatile chemicals, and describes recent developments in psychophysical methods for evaluating chemical irritancy in humans, and discusses some of the many non-sensory factors such as exposure history, attitudes and expectations and personality variables that can significantly alter the perception of odor, irritation and health risk following exposure to a volatile chemical. RESULTS: The availability of safe, non-invasive assays to measure directly odor and irritant responses in the species of interest, humans, can both simplify and improve accuracy in the process of developing appropriate occupational exposure guidelines. CONCLUSIONS: Objective measures of irritation onset obtained in conjunction with subjective responses can lend valuable input to the decision process for determining occupational exposure limits but should always account for other factors (e.g., cognitive or emotional) that may be modulating the subjective response.