Evaluation of Health Hazard of Amorphous Silica-Coated Cristobalite Folowing Intratracheal Injection in Rats.
Johnson GT; Lewis TR; Groth DH
NIOSH 1973 Jan:12 pages
The subchronic toxicity of industrial silica (7631869) dusts was studied. Dusts collected in baghouses of a metallurgical facility consisted of silica coated cristobalite (14464461) particles. Adult albino-rats were injected intratracheally with saline suspensions of 10 milligrams of silica dusts or quartz dusts as a positive control. Animals were observed daily for appearance, mortality, and behavior. Pulmonary lymph nodes, lungs, and spleens were examined histologically at 3, 6, and 9 months post treatment. Gross and splenic observations were negative. Granulomatous pulmonary inflammatory lesions with crystalline particulate inclusions were observed in both silica and quartz exposed animals after 3 months. Collagen content of the lesions was greater at 6 months, and at 9 months a reduction in the number of cells in the granulomas was observed. Silica dust and quartz induced lesions were very similar. The authors conclude that siliceous dusts have the potential for producing granulomatous pulmonary lesions in humans. They recommend that engineering controls be installed and that threshold limits for exposure be based on existing quartz exposure limits.
Silicates; Mineral-dusts; Laboratory-animals; Dust-exposure; Lung-lesions; Comparative-toxicology; Pulmonary-system-disorders;
NTIS Accession No.
NIOSH, U.S. Department of Health, Education and Welfare, Cincinnati, Ohio, 12 pages