| Abstract |
The fibrogenicity of silica (7631869), bentonite (1302789), kaolin (1332587), talc (14807966), vermiculite (1318009), feldspar, and coal in animals in nose only exposures was investigated, and the cytotoxicity of the minerals was studied in in-vitro tests. Data were evaluated to provide comparative cytotoxic correlations on fibrogenicity and information for interpreting human exposure effects. Enzymes were measured as indicators of adverse activity of minerals on macrophages. Results of physical and chemical analysis of the minerals showed that all minerals tested wre smaller than 7 micrometers and were within the respirable size range. In in-vitro hemolysis studies, bentonite, kaolin, silica, and vermiculite showed the greatest hemolysis, and talc, coal, and feldspar showed the least. Release of cytosolic enzyme lactate-dehydrogenase, indicative of membrane damage, was significant with kaolin, silica, and vermiculite and least with talc, coal and bentonite. The studies suggested that silica, kaolin, bentonite, vermiculite and feldspar all induced an initial acute pulmonary response, but that there appeared to be no correlation between this acute response in-vivo and their chronic pulmonary response. The studies also indicated that the initial pulmonary response reflected in-vitro was not correlated with the chronic response to the dust. |
