Emphysema and Pneumoconiosis

Dust burdens of quartz and bituminous coal, respectively, were imposed upon the lungs of rats, guinea pigs, and hamsters by inhalation after the production of emphysema with papain and by intratracheal injections of dust prior to papain-induced emphysema. Animals with papain-induced emphysema had less dust in the lungs than nonemphysematous animals that had inhaled the same dusts for the same length of time or that had been injected with the same amount of dust. Abundant dust was present in nonemphysematous portions of the lungs, whereas in regions of emphysema, little or no dust was found. Supple alveolar walls, requisite to the sequestration of dust and the formation of dust depots, have been destroyed in emphysematous foci, thereby favoring dust clearance.