Guidelines for measuring chemically induced cell proliferation in specific rodent target organs.

A larger data base will be required to relate the extent, duration, and nature of chemically induced cell proliferation to carcinogenic potential and to establish the importance of this end point in chemical carcinogenesis. As that relationship becomes clearer, the information gained will become valuable in investigations of mechanisms of carcinogenesis, development of short-term tests for nongenotoxic carcinogens, selection of appropriate doses for cancer bioassays, and in the formulation of improved risk-assessment models. Because the quality of chemically induced cell replication data depends on the procedures and protocols followed for these labor-intensive studies, efforts among laboratories must be coordinated so that the work and the expenditure of substantial resources will yield a cohesive data base.