Issues in Assessing and Regulating Particulate Exposures in Occupational Environments

Abstract

Exposures are regulated for only a few of the many chemicals currently produced in the occupational environment. Regulation of particulate exposures should include an improved generic particulate exposure limit (GPEL) set to protect the health of the respiratory system by preventing overload of the lung respiratory clearance system and its auxiliary effects. Development of the GPEL should use human respiratory dose models that can incorporate the effects of overload kinetics on particle clearance, use exposure data collected with size-selective samplers, and account for differences in worker physiology and breathing rates. A systematic method of screening occupational dusts for local respiratory system toxicity beyond that produced by dust overload is needed. Such a toxicity screen could be used to reduce the default GPEL proportionate to the hazard. Work is also needed to assess the validity of the equal additivity assumption of toxicity implied by using the default GPEL for complex dust mixtures.