摘要：Health risk analysis needs to apply newer developments in the understanding of the underlying mechanisms of the carcinogenic process which has allowed for the classification of chemical carcinogens into those that damage genetic material directly (genotoxic carcinogens) and those that operate by indirect or epigenetic mechanisms. We propose a systematic decision point approach for detecting and evaluating substances for carcinogenic risk. This approach recognizes that genotoxic and epigenetic agents operate by different mechanisms and distinguishes between these two categories of carcinogens primarily on the basis of results in a battery of short-term tests that includes systems which reliably detect genotoxic carcinogens and others which may respond to epigenetic agents. Genotoxic carcinogens at very low dosages may have practical, effective threshold no-effect levels, but, nevertheless, because of their mechanism of action they are regarded as a qualitative hazard. The action of epigenetic agents of the promoter class is highly dose-dependent and reversible, and thus, a distinctively different health risk analysis is required for these agents to take account of their quantitatively lesser hazard. Full text Full text is available as a scanned copy of the original print version. Get a printable copy (PDF file) of the complete article (2.3M), or click on a page image below to browse page by page. Links to PubMed are also available for Selected References . 233 234 235 236 237 238 239 240 241 242 243 244 245
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