TOXICOLOGICAL INVESTIGATIONS ON SILICON-CARBIDE .1. INHALATION STUDIES

The question of lung damage as a result of exposure to silicon carbide (SiC) was investigated by inhalation experiments to obtain informatio n on the qualitative response of lung tissue to the test substance (Si C). For comparison, quartz, kaolinite, and tempered clay dusts were us ed. The indices for the effects of the dusts studied were organ weight s, numbers of bronchoalveolar cells, lung surfactant phospholipid conc entrations including subfractions, and lung clearance. Exposure to the test samples was carried out according to the Essen inhalation model in two independent series. The results of the two series were similar: Compared with sham controls, exposure to SiC did not affect the indic es studied. Even at a low dose (a quarter of the SiC dose) quartz gave pronounced deviations in all indices. In particular, an increase in g ranulocytes indicated toxic properties of the dust. The long term elim ination of quartz from the lung was worse than that of SiC. The kaolin ite and tempered clay dusts were intermediate between SiC and quartz b ased on several of the indices studied. It is concluded that SiC is de posited practically inert in the lung.