The genotoxic/epigenetic distinction: relevance to cancer policy.

Should federal agencies use separate, less stringent guidelines for regulating epigenetic or nongenotoxic carcinogens on the assumption that thresholds are likely to exist for these agents? This article reviews recent initiatives by the Environmental Protection Agency that either propose or informally adopt this approach in light of responses from the scientific community and a review of the recent literature. Relevant background is provided by current research concerning the role of chromosomal damage and oncogene activation in carcinogenesis along with findings that classical promoters or "epigenetic" agents can induce both DNA damage and chromosomal rearrangements. The conclusion is that such a revision of cancer policy is not now supported by available scientific data concerning chemical carcinogenesis.