Leukemias and vaginal tumors induced in female Donryu rats by continuous administration of 1-butyl-3,3-dimethyl-1-nitrosourea in the drinking water.

Three groups of Donryu rats, each consisting of 36 females, were continuously given solutions of 1-butyl-3,3-dimethyl-1-nitrosourea as drinking water (400 ppm for group A, 200 ppm for group B 100 ppm for group C). Of the 100 rats that survived at least 122 experimental days, 64 developed leukemia and 38 had vaginal tumors. Leukemias were preponderant in animals of groups A and B; vaginal tumors appeared in group C.