Carcinogenicity of N-phenyl-1-naphthylamine and N-phenyl-2-naphthylamine in mice.

Technical N-phenyl-1-naphthylamine ( PANA ), which is an optic isomer of N-phenyl-2-naphthylamine ( PBNA ), has been used as a rubber additive without suspicion of its being carcinogenic. When male ICR mice were given repeated s.c. injections of both technical and pure PANA in dimethyl sulfoxide, it resulted in high percentage of malignant tumors similar to that in mice given technical PBNA . PANA had a tendency to induce hemangiosarcoma. Similar injections of PANA and PBNA into male TA-1 mice gave similar results. Previous unilateral nephrectomy enhanced both PANA and PBNA induction of renal hemangiosarcomas. The similar carcinogenic potency of PANA and PBNA suggests other routes of metabolic activation besides dephenylation for both chemicals in mice.