[Experimental studies concerning the exact determination of the etiopathogenesis of pneumoconiosis of coal miners].

The effects have been studied of some pure charcoal powder, and of mixed "coal pit" powder which are representative for the basin in the Jiu Valley. A total of 48 samples have been studied as such and after addition of quartz graduated to contain 5, 10, 15, 20 and 25% quartz. The aim of the study was to determine the type of pneumoconioses induced by the various powders, to establish the role of quartz particles and the threshold at which quartz addition will impart silicogenic properties to the dust particles. A total of 300 Wistar rats have received intra-tracheal doses of an unique amount of 50 mg suspension as such and with added quartz. The rats were distributed in 12 groups. Three animals in each group were sacrificed at 6 and 12 months after instillation and histopathologic studies of the lungs were performed. Addition of 10% quartz dust to the charcoal powder, and of 15% to the "coal pit" powder imparted silicogenic properties to the samples. Both powders have masked to a certain extent the effects of the added quartz, the protective effects being exerted by minerals associated to charcoal (silicates, metallic oxides, etc.). In the mining area investigated pneumoconioses and silicosis represent two distinct pathological entities, and the role of the quartz particles in the genesis of pneumoconioses in this particular area appears to be limited.