Dose- and time-response of colon carcinogenesis in Fischer-344 rats after a single dose of 1,2-dimethylhydrazine.

The purpose of this experiment was to examine the development of colon tumors after the injection of a single dose of 1,2-dimethylhydrazine (DMH) in rats. Male Fischer-344 rats were injected with 0, 10, 30, 100 or 200 mg/kg of DMH dihydrochloride. No tumors were seen after 3 or 5 months at any dose, but were seen after 7 or 9 months. At 9 months, tumors were induced in a dose-dependent manner, with 64.7% of rats receiving the 200 mg/kg dose developing tumors. This study shows that a high incidence of colon tumors can be induced by a single dose of DMH after a 9-month latency period.