A carcinogenicity dose response study by continuous administration of 1,2-dimethylhydrazine dihydrochloride in mice.

A dose response study in carcinogenesis by 1,2-dimethylhydrazine dihydrochloride (1,2-DMH) in Swiss mice was performed. The compound was administered continuously in drinking water for life from 6 weeks of age at dose levels of 0.002, 0.001, 0.0005, 0.00025, 0.000125, 0.0000625, 0.00003125 and 0.000015625%. A positive correlation was established between the dose levels of 1,2-DMH and the yield of blood vessel tumors. In addition, the latency periods for these tumors diminished when the dose levels of the carcinogen decreased. Although some of the treatments induced lung tumors, no association was observed between the dose levels of the carcinogen and the lung tumor incidence. The study thus provides an example in which the continuous lifespan administration of a carcinogen resulted in a partial dose response effect. This method of administration closely resembles some of the human exposure situation.