Acute exposure assessment

In an acute exposure assessment, the short term exposure to a substance or group of substances is estimated. The interest is in the distribution of individual day exposures and derived statistics like the fraction of days that exceed an intake limit or point of departure (PoD). The PoD is calculated as the acute reference dose (ARfD) * safety factor (SF). The basic model for the exposure to a substance in an acute exposure assessment is:

y_{i j} = \frac{\sum_{k = 1}^{p} x_{i j k} c_{i j k}}{b w_{i}}

where $y_{i j}$ is the intake by individual $i$ on day $j$ (in microgram substance per kg body weight), $x_{i j k}$ is the consumption by individual $i$ on day $j$ of food $k$ (in g), $c_{i j k}$ is the (simulated) concentration of that substance in food $k$ eaten by individual $i$ on day $j$ (in mg/kg), and $b w_{i}$ is the body weight of individual $i$ (in kg). Finally, $p$ is the number of foods accounted for in the model. Within parenthesis, the default unit definitions are assumed, but decimal multiples or submultiples of units are easily specified using the relevant tables.

In the exposure assessment, individual days enter the Monte Carlo sample using the inverse of the sampling weights $w_{i}$ when the number of MC iterations is > 0 (see table for Individuals, field SamplingWeight).

Figure 42 Example MCRA dietary exposure contributions foods as measured.

Figure 43 Example MCRA dietary exposure contributions foods as eaten

Figure 44 Example MCRA dietary exposure contributions substances

Figure 45 Example MCRA dietary exposure contributions foods as measured x substances

Modelling unit-to-unit variation