[Change of toxicity and carcinogenicity of N-methyl-N-nitrosobenzylamine in rats by methylsubstitution in the phenylresidue].

Substitution with a methyl group in the 2-, 3- or 4-position respectively of the phenyl moiety of N-methyl-N-nitrosobenzylamine results in a considerable reduction of the acute toxicity. (LD 50 of MNBA: 18 mg/kg (Druckrey et al., 1967), 2-Me-MNBA: 90 mg/kg, 3-Me-MNBA: 600 mg/kg, 4-Me-MNBA: 400 mg/kg). However, the introduction of the methyl group influences the carcinogenic activity of MNBA in rats and its organotropy, only to a small extent. Long-term administration of 5 and 15 ppm respectively of the isomeric N-nitroso compounds in the drinking water produces in all animals carcinomas of the oesophagus and the pharynx.