Health Risk Science - Dose-response

Dose response assessment involves examination of the relationship of the magnitude of exposure and the probability of occurrence of the health effects in question in exposed population. Elements considered in the assessment are the intensity of exposure, age, pattern of exposure and other important characteristics such as sex, lifestyle and some modifiable elements. Extrapolation of results of high to low dose and animal to humans is usually necessary in dose response assessment although methods used to extrapolate results should take into account any statistical and biological uncertainties. A dose response relation determined from epidemiological studies is rare but not impossible but often require extrapolations to lower exposures of the general population introducing uncertainties especially for sub-groups like children. When dose-response is absent from human studies, tests performed on animals on high and low dose (rats and mice) are needed to determine to existence of a dose response relationship. However, extrapolations are often needed because humans are exposed to low doses thus introducing several uncertainties in predicting a dose response relation for a substance.