Tumor induction by a single subcutaneous injection of 1-butyl-1-nitrosourea or 1-butylurea in newborn mice.

A subcutaneous injection of 1-butyl-1-nitrosourea (BNU) at the maximum tolerated dose (333 mg/kg body wt.) to newborn CDF1 mice induced adenocarcinoma and adenoma of the lung, adenoma of the liver, thymic or non-thymic lymphoma and neurinoma of the acusticus nerve; the total incidence of tumors was statistically significant as compared with that of control. However, in the 1-butylurea (BU) mice, one adenoma of the lung was induced in a male mouse; the total incidence of tumor was comparable to that of control.