Twenty eight newborn mice (Mus musculus) consist of 14 males and 14 females have been treated with benzo(a) pyrene (BP) which were dissolved in dimethylsulfoxide (DMSO) solution. The lung tumour induction has been done by intraperitoneally injection of the solution at the first day of age using doses of 0.2 umol BO/0.025 cc DMSO, 8th day of age using doses of 0.4 umol BP/0.025 cc DMSO, and 15th…