The potential for the use of cell proliferation studies in carcinogen risk assessment.

The use of observations on cellular proliferation in assessing the mechanism of action of certain factors in the genesis of tumors of the urinary bladder, forestomach, and intestine, or on the effects of dietary restriction, is illustrated. It is suggested that, particularly with nongenotoxic carcinogens, such studies may be of great use in risk assessment especially for those cases in which animals are exposed at very much higher levels of the test agent in the carcinogenesis bioassay than are humans as the result of the environmental or other use of the agent.