Document 4aRqRLjeBXVOZq8yEynG8Og41

Maltoni & Lcicmine: Carcinogenicity Bioassays 209 Figure 2. Pulmonary metastasis of well differentiated Zymbal gland carcinoma in rat. H&E, X 190. 2. The range of induced tumors varies to some extent from species to species. When given by inhalation VC produced: in rats, Zymbal gland carcinomas, neph roblastomas, angiosarcomas, and angiomas of the liver and other sites, skin car cinomas, hepatomas, and brain neuroblastomas; in mice, lung adenomas (fre quently undergoing malignant transformation), mammary carcinomas, of a peculiar type, angiosarcomas and angiomas of the liver and of other sites, skin epithelial tumors; in hamsters, liver angiosarcomas ahdt as early evidence seems to suggest, skin trichoepitheliomas and lymphomas. Incidentally, liver angio sarcomas have been observed in all three animal species. 3. In the BT1 and BT4 experiments, VC shows a carcinogenic effect at 50 ppm. 4. From the UT1 experiment (the only one completed) a dose-response rela Figure 3. Nephroblastoma in rat. H&E, X 470. tionship clearly emerges, as far as angiosarcomas and nephroblastomas are con cerned, in the lower dose ranges: from 500 to 50 ppm for angiosarcomas and from 250 to 50 ppm for nephroblastomas. 5. A comparison of the results available at the present moment in rats ex posed for 12 and 4 months (BT1 and BT3 experiments) shows that the neoplastic response, as far as angiosarcomas and nephroblastomas are concerned, is affected by the length of exposure to VC. 6. The comparison of the results obtained in rats of two different strains, i.c , Sprague-Dawley (BT1) and Wistar (BT7), at the present moment, seems to suggoj^fhat the strain factor considerably affects the neoplastic response, 7. The onset of two subcutaneous angiosarcomas in the offspring of breeders exposed during pregnancy for 7 days appears to indicate s transplacental effect \k SL 072973