Experimental study on the fibrogenic properties of different types of alumina.

The fibrogenicity of seven alumina samples was tested in rats by intratracheal instillation, and in mice by intraperitoneal injection. Histopathological studies were carried out on all animals. As an indicator for inflammatory reaction, a bronchoalveolar lavage (BAL) was performed in rats. Lactate dehydrogenase activity and protein content of the supernatant as well as the free-cell population of the lungs were studied. None of the five aluminas used for primary aluminum production showed any fibrogenic potential, while the other two, a chemical grade and a laboratory produced sample, induced fibrotic lesions. A correlation between cytological and biochemical parameters studied in BAL and the fibrosis determined by histology could be established for the quartz-treated rats, but not in the alumina-treated animals.