Induction of tumors in transplacental or neonatal mice administered 3'-methyl-4-dimethylaminoazobenzene or 4-aminoazobenzene.

The maximum tolerated dose of 3'-methyl-4-dimethylaminoazobenzene (3'-Me-DAB) or 4-aminoazobenzene (AB) was administered subcutaneously to pregnant ICR/JCL mice on days 15, 17 and 19 of gestation, or to neonatal mice. All animals were killed at 1 year of age. In the transplacental treatment, 3'-Me-DAB induced neoplastic lesions in liver and lung, but the incidence in mice treated with AB was not significantly different to that of the controls. Following neonatal treatment, mice treated with 3'-Me-DAB or AB developed neoplastic lesions of liver, lung and lymphoreticular tissues.