Production of Leukemia and Stomach Neoplasms in Swiss, RF, BALB/c, and C3H Female Mice by Feeding N-[4-(5-Nitro-2-furyl)-2-thiazolyl] acetamide

N-[4-(5-Nitro-2-furyl)-2-thiazolyl] acetamide was fed to female 5-week-old Swiss mice at a dose of 0.1% by weight of diet for 13 weeks, with a cumulative dose of 490 mg/mouse/ 13 weeks. The mice were observed for an additional 14-week period while being fed control diet. Because of the sudden appearance of leukemia during the 13th week and cannibalization of moribund mice by other mice, only 16 mice survived at least 17 weeks to be grossly and microscopically evaluated. Of these, 15 had generalized lymphocytic leukemia and 3 had squamous cell tumors of the stomach. In the control group of 56 mice, no cancers were detected during the 27-week period of observation. For determination of the effect of dosage, groups of 30 female 5-week-old Swiss mice were fed NFTA at dietary levels of 0.1, 0.05, 0.025, and 0.01% for 14 weeks. The respective leukemia incidences were 8/9, 9/13, 8/16, and 7/14. The latent period was 12 weeks for the 0.1 and 0.05% groups and 18 weeks for the 0.025 and 0.01% groups. Stomach tumors were present in 12/52 mice. In the control group of 35 mice, 1 mouse developed a pulmonary adenoma. RF, BALB/c, and C3H female mice, regarded as having a low incidence of spontaneous leukemia, were as susceptible to the leukemogenic effect of NFTA as were Swiss mice. The following incidences of leukemia were observed after 14 weeks of feeding a diet composed of 0.1% NFTA: RF, 12/16 (controls, 3/16); BALB/c, 21/29; C3H, 12/24; and Swiss, 22/22. A low incidence of stomach tumors was found in all NFTA-treated groups.