. "4 A Model for the Development of Tolerable Upper Intake Levels for Nutrients." Dietary Reference Intakes for Vitamin C, Vitamin E, Selenium, and Carotenoids. Washington, DC: The National Academies Press, 2000.
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DRI DIETARY REFERENCE INTAKES FOR Vitamin C, Vitamin E, Selenium, and Carotenoids
FIGURE 4-3 Illustration of the population at risk from excessive nutrient intakes. The fraction of the population consistently consuming a nutrient at intake levels in excess of the UL is potentially at risk of adverse health effects. See text for a discussion of additional factors necessary to judge the significance of the risk. LOAEL = lowest-observed-adverse-effect level, NOAEL = no-observed-adverse-effect level, UL= Tolerable Upper Intake Level.
For risk management decisions, it is useful to evaluate the public health significance of the risk, and information contained in the risk characterization is critical for this purpose.
Thus, the significance of the risk to a population consuming a nutrient in excess of the UL is determined by the following:
the fraction of the population consistently consuming the nutrient at intake levels in excess of the UL;
the seriousness of the adverse effects associated with the nutrient;
the extent to which the effect is reversible when intakes are reduced to levels less than the UL; and
the fraction of the population with consistent intakes above the NOAEL or even the LOAEL.
Thus, the significance of the risk of excessive nutrient intake cannot be judged only by reference to Figure 4-3, but requires careful