title: Hypothetical dose-response curves for chronic exposures to mutagens or carcinogens subject to simple enzymatic detoxification in the mammalian body.
abstract: Dose-response curves for chemical carcinogenesis and mutagenesis in the whole mammal may be influenced (a) by processes affecting the delivery of the applied dose to the DNA of the target cell or (b) by processes affecting the response of the cell to the initial DNA damage. As an example of the former, the effect of a simple enzymatic detoxification system on the delivery to the target organ of an applied chronic dose has been considered. In certain circumstances as the applied dose is lowered, the delivered dose may become proportionately less than at high doses so that a new linear relation of lower slope is established. Such a biphasic curve is termed quasi-threshold to distinguish it from a true threshold. The slope at low doses could in principle be extrapolated to very low doses in the estimation of genetic risk.
mesh_terms: D000818:Animals; D001711:Biotransformation; D002273:Carcinogens; D004247:DNA; D004305:Dose-Response Relationship, Drug; D004781:Environmental Exposure; D004785:Environmental Pollutants; D006801:Humans; D008658:Inactivation, Metabolic; D008322:Mammals; D009153:Mutagens; D009154:Mutation
chemical_list: D002273:Carcinogens; D004785:Environmental Pollutants; D009153:Mutagens; D004247:DNA