3500 mg/day

Vitamin D

10 mg

100 mg

Vitamin A

800 male, 1000 female (mg REa)

500,000 mg RE

Vitamin E

8 male, 10 female (mg TEa)

800-3200 mg/day

aRE, retinol equivalents; TE, a-tocopherol equivalents.

aRE, retinol equivalents; TE, a-tocopherol equivalents.

Dose can have different meanings, as the examples show. The use of mass per unit body weight is ideal, as it ensures that the exposure of each individual is accurately known. However, concentration units are often appropriate, especially with reference to environmental pollution (mass/volume in air or water, or mass/mass in solids such as food or soil). The concentration can refer to that of ambient air or water, of ingested food or water, or of a preparation to be applied to the skin or elsewhere. Or, in the case where the toxicant is a complex mixture such as wastewater treatment plant effluent, one uses dilutions measured in percent (volume/volume). In these cases it is more proper to talk about the dose-concentration relationship.

Dose-response relationships can be divided into two types, based on the kind of information used to describe them. One is the simpler empirical model, which begins with assumptions about the shape of the dose-response relationship. These are called tolerance distribution models. The other type is fundamental, based on knowledge or assumptions about how a toxin acts. These are called mechanistic models.

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