The Challenge of Setting Occupational Exposure Limits (OELs) for Odorants and Irritants

Abstract

MAB3-PD-02 Introduction: Setting occupational exposure limits (OELs) for odorous or irritating chemicals is a global occupational health challenge. Industrial hygienists and toxicologists are expected to set OELs for the numerous chemicals that are being introduced to the workplace. Often, however, there is inadequate knowledge about the toxicology of these chemicals and, if they are odorous or a sensory irritant, these characteristics are usually not recognized until they are used in large quantities. This paper presents a novel and simple method for setting OELs based on chemosensory models, taking into account odor and irritation thresholds. Methods: The importance of accounting for risk perception and communication, conditioned responses, interindividual variability in tolerance, detection, and susceptibility when identifying an appropriate workplace concentration of odorous or irritant compounds is evaluated according to 3 chemosensory models defined by a chemical's odor and irritation thresholds. These parameters are then incorporated into a flowchart style methodology, which can be used to set an OEL for a specific chemical. Results: Our analysis indicates the OEL identified for a chemical odorant or irritant will depend on the type of chemosensory effect that the chemical is likely to exhibit. Experience has shown that chemicals with a low odor threshold often require low OELs, even though many do not pose toxicity or irritation at those air concentrations. Discussion and Conclusions: There remains a need for OEL-setting organizations around the world to agree upon the percentage of the workforce that an OEL should protect and the types of toxicologic endpoints that are sufficiently important to protect against (eg, transient eye irritation, enzyme induction, or other reversible effects). This is particularly true for the odorants and irritants. In the main, the methods presented here are worthy of consideration in the setting of OELs until better and more thorough consensus among professions is reached. This method could also be extended to environmental regulation where risk perception plays a dominate role in whether the public views the exposure as being reasonable or safe.