Response of alveolar macrophages to in vitro exposure to freshly fractured versus aged silica dust: the ability of prosil 28, an organosilane material to coat silica and reduce its biological activity.
Vallyathan-V; Kang-JH; Dyke-K; Dalal-NS; Castranova-V
J Toxicol Environ Health 1991 Jul; 33(3):303-315
The cytotoxic effects of freshly ground or aged crystalline silica (14808607) on alveolar macrophages were examined. The effects of prosil-28, an organosilane material used to coat the silica, on its biological activity were also investigated. Alveolar macrophages harvested from male Sprague-Dawley-rats by pulmonary lavage were incubated with freshly cleaved crystalline silica or silica that had been aged up to 2 weeks after cleavage. Concentrations ranged up to 20mg/ml. Cytotoxicity was assessed by determining cell viability by means of the trypan-blue test or propidium fluorescence, the extent of hydrogen-peroxide release, the degree of cellular chemiluminescence after stimulation by lucigenin, or the extent of hemolysis of sheep red blood cells (SRBCs). A similar experiment was performed in which freshly cleaved silica was coated with prosil. The viability of macrophages treated with freshly ground and aged silica was 41 and 83%, respectively. The difference was statistically significant. Freshly cleaved and aged silica both significantly increased macrophage secretion of hydrogen-peroxide; freshly ground silica was 50% more potent than aged silica. Both types of silica stimulated chemical luminescence; however, the potency of aged silica was only 18 to 39% that of freshly cleaved silica. Coating freshly ground silica with prosil decreased the ability of the dust to hemolyze SRBCs by 53 to 73% and cellular chemiluminescence by 58%. The authors conclude that freshly cleaved crystalline silica is more bioactive than aged silica, and could be more potent in inducing pulmonary disease. Coating freshly ground silica with prosil appears to reduce its in-vitro cytotoxicity. Freshly ground silica could possibly be made less harmful in occupational settings by incorporating prosil into water sprays of drill bits.
NIOSH-Author; In-vitro-studies; Lung-cells; Silica-dusts; Cytotoxic-effects; Surface-properties; Age-factors; Alveolar-cells; Coatings; Physiological-response; Mammalian-cells; In-vitro-studies
Journal of Toxicology and Environmental Health