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Chronic Effects of Inhaled Amorphous Silicas in Animals.

Groth-DH; Moorman-WJ; Lynch-DW; Stettler-LE; Wagner-WD; Hornung-RW
In the Proceedings of Symposium on Health Effects of Synthetic Silica Particulates, Marbella, Spain 1979 Nov:118-143
The pulmonary toxicity of amorphous silica (7631869) fume, gel, and precipitate was investigated. Sprague-Dawley-rats, Hartley-guinea- pigs, and Cynomolgus-monkeys were exposed by inhalation to 15 milligrams per cubic meter of one of the types of silica for 5.5 to 6 hours per day, 5 days per week. Pulmonary function was tested periodically in monkeys. Rats were autopsied after 3, 6, or 12 months of exposure, and monkeys and guinea-pigs were autopsied after 10 to 18 months of exposure. In the monkeys, the lungs contained large numbers of macrophages and mononuclear cell aggregates, regardless of the type of amorphous silica to which they were exposed. Fewer and smaller particles were seen in the lungs of exposed rats and guinea-pigs. Significant amounts of collagen were found in the lungs of monkeys exposed to silica fume. Among the monkeys exposed to the fume, marked changes occurred in lung volume and ventilatory mechanisms. Exposure of monkeys to the silica precipitate produced changes in lung volume, while exposure to silica gel produced changes in ventilatory performance and mechanical properties. The authors recommend reevaluation of existing standards for synthetic amorphous silica exposure.
Silicates; Laboratory-animals; Comparative-toxicology; Mineral-dusts; Dust-inhalation; Lung-disorders; Pulmonary-function;
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In the Proceedings of Symposium on Health Effects of Synthetic Silica Particulates, Marbella, Spain