The carcinogenic effect of intracolonic administration of 1,2-dimethylhydrazine dihydrochloride in mice

1,2-Dimethylhydrazine dihydrochloride (1,2-DMH) was given to Swiss mice in 1 or 10 weekly intracolonic instillations of 60 and 40 micrograms/g body weight, respectively. In mice that received a single treatment, the tumor incidences in the lungs, blood vessels and subcutis were 34% (p less than 0.006), 8 and 25 in females and 2, 20 and 0% in males, respectively. In mice treated repeatedly with the carcinogen, the corresponding tumor incidences were 34% (p less than 0.006), 38% (p less than 0.000001) and 12% (p less than 0.03) in females and 34, 10 and 0% in males, respectively. In control mice the tumor incidences in lungs, blood vessels and subcutis were 15, 8 and 2% in females and 22, 5 and 2% in males, respectively. The induction of large intestinal cancer, which was the main objective of this investigation, however, failed to materialize.