REGIONAL DEPOSITION OF GASES AND PARTICLES IN THE LUNG - IMPLICATIONSFOR MIXTURES

Considerations of the health effects of pollutant mixtures usually foc us on the interactions of biochemically-induced events. For example, t he effect of metabolic enzyme induction by one pollutant on the subseq uent effect of another pollutant is often considered. Another importan t aspect of mixture interactions is the modulating effects exposure to one pollutant can have on the dosimetry of another pollutant and, ind irectly, on the effects of the other pollutant. Dose-modulating effect s may be particularly important when considering effects of inhaled mi xtures on the lung. In this paper, the specific case of O-3-induced ch anges on the human lung and the resulting effects on inhaled particle dose are considered as a specific example. Ozone has multiple effects on the lung ranging from alterations in pulmonary function to effects on lung defense mechanisms such as mucociliary transport of particles, and alveolar macrophage engulfment and translocation. To better under stand how the O-3-induced changes can affect particle dosimetry, the b asic concepts of particle dosimetry are considered first. Then the spe cific O-3-induced effects on the human lung are considered in the cont ext of the factors governing inhaled particle dose.