N6(Methylnitroso)adenosine: a carcinogenic nitrosamine derived from a naturally-occurring nucleoside

N6(Methylnitroso) adenosine (M6(NO)Ado) is found readily under acidic conditions by the interaction of nitrite with 6-methyladenosine, a naturally-occurring nucleoside. Swiss mice were treated with M6(NO)Ado by injection (40 mg/kg each treatment) transplacentally and then as newborns and young adults. The incidences of lymphomas, primary lung tumors, and hepatic neoplasms were significantly greater in these treated animals than in controls. These results demonstrate the tumorigenicity of M6(NO)Ado.