Do Carcinogens Have a Threshold Dose? Pro and Contra
With sound understanding of biological concepts, the notion of threshold effect levels has grown in acceptance especially for electrophile-induced mutations. However, mutagenesis is one part of the exposure-to-tumor process in chemical carcinogenesis. In the following chapter, we postulate diverse protective mechanisms that may contribute to no-effect thresholds in chemical carcinogenesis. Key mechanisms contributing to threshold doses are carcinogen detoxification and DNA repair. Elimination of cells harboring premutagenic DNA lesions by apoptosis and other cell death pathways and reduced proliferation rates within tissues may minimize mutation rates and therefore, contribute to threshold dose effects.
KeywordsNucleotide Excision Repair Base Excision Repair Threshold Dose MGMT Gene Genotoxic Carcinogen
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