Cocarcinogenicity Of Foundry Particulates In Hamsters.
Niemeier-RW; Mulligan-LT; Rowland-J; Stettler-LE
The cocarcinogenicity of industrial particulates, silica (7631869) and its substitutes was studied in hamsters. Outbred male Syrian- Golden-hamsters were exposed to suspensions of silica particulates either alone or in combination with 3 milligrams of benzo(a)pyrene (50328) (BaP), or to saline alone, by intratracheal instillation once a week for 15 weeks. Mortality and morbidity were observed twice daily, and body weights were recorded weekly for 15 weeks and biweekly thereafter. All surviving hamsters were killed 92 weeks after exposure. Complete necropsies were performed on all dead animals and on animals killed when moribund or at end of the 92 week study period. Lungs were excised, weighed, and subjected to histopathological examination. Data was analyzed for statistical significance. Significant weight loss occurred in hamsters exposed to BaP or silica particulates, but this was not correlated with survival. Silica sand, minusil (7631869), and a mixture of minusil and ferric-oxide (1309371) significantly increased the mean lung weights, and correlated with increased incidences of granulomatous inflammation. Clinical signs in hamsters after exposure to silica particulates were wheezing, dyspnea, and polypnea. A significant cocarcinogenic response was observed for all silica particulates except aluminum (7429905). Cocarcinogenicity was manifested by increased incidences of malignant lung tumors caused by BaP. The authors conclude that silica and its substitutes elicit cocarcinogenicity in BaP induced lung cancer.
NIOSH-Author; Laboratory-animals; Exposure-levels; Histopathology; Dust-exposure; Biological-effects; Physiological-response; Quantitative-analysis; Mortality-rates; Toxic-materials;
7631-86-9; 50-32-8; 7631-86-9; 1309-37-1; 7429-90-5;
Division of Biomedical and Behavioral Science, NIOSH, U.S. Department of Health and Human Services, Cincinnati, Ohio, 24 pages