Chronic exposure assessment
In a chronic exposure assessment, usual exposure is defined as the long-run average of daily exposure to a substance or group of substances by an individual. The interest is in the distribution of individual exposures and derived statistics like the fraction of individuals that exceed an intake limit or point of departure PoD). The PoD is calculated as the average daily intake (ADI) * safety factor (SF). Usually, for an individual, dietary recall data are available on 2 (or more) consecutive days. We assume an equal number of days for each individual, unless specified differently in table for Individuals.
For a chronic exposure assessment the available data are used to calculate exposures per person-day (daily exposure):
where \(y_{ij}\), \(x_{ijk}\) and \(\mathit{bw}_{i}\) are defined as before but now concentrations of the substance found in food \(k\) enter the model as the estimated mean substance concentration value \(c_{k}\). Using the person-day exposures MCRA, provides a number of exposure models to calculate the distribution of usual exposure at the person level.