Examination of the carcinogenic and cocarcinogenic effects of Grenz radiation.

The effects of the chemical carcinogen 7,12-dimethylbenz(a)anthracene on long-wavelength ionizing radiation (grenz ray)-induced carcinogenesis in the skin of hairless mice were examined. A carcinogenic amount of the grenz energy (20,500 R) was applied over a 12-month period. A single application of 7,12-dimethylbenz(a)anthracene 4 weeks before the initiation of the grenz ray exposures resulted in a significant acceleration of tumor growth and the incidence of deeply invading cancers. These findings simulate the influence of 7,12-dimethylbenz(a)anthracene ultraviolet-induced cancer formation, and confirm the additive effects of physical and chemical carcinogenic stimuli.