1.2.1 Acute exposure

To estimate the acute exposure to a compound via the diet three calculation models can be used:

Point estimates

In the point estimate approach a fixed high level of consumption is multiplied with a fixed high residue level. This level is divided by a single mean consumer body weight value to achieve a high exposure level per kg body weight. The way to calculate it is as follows:

(consumption level x compound level)  / body weight

Point estimates of acute exposure are almost only performed in relation to pesticides. They are used in the regulatory process of setting maximum residue limits for crops. In this equation a single high residue level (the highest residue level from a set of field trial data) is multiplied with a single high consumption level for each crop addressed (the 97.5th percentile of the consumption distribution addressing only those consuming the crop on a certain day; so-called large portion size). In this way a single high value for the estimation of the dietary exposure is derived.

This technique is used worldwide within the field of pesticides and has proved useful since the estimates are simple to calculate and relatively easy to understand.

Simple distributions / semi probabilistic

In the case of simple distributions / semi-probabilistic a distribution of compound or consumption levels is used. In an acute assessment mostly a fixed upper concentration level of the compound in a food is multiplied with a range of daily consumption levels of the relevant food. In this approach all daily consumption levels of a food as obtained in a dietary survey are taken into account. Because a high level of the compound is used only one food at the time can be addressed. Assuming that people consume different foods all contaminated at the highest level is an unrealistic worst-case approach. An alternative approach is to multiply the consumption levels of one food with an upper level and the other foods with a mean, background level. In that case the whole diet can be addressed. The result of this approach (either with one food or the whole diet) is a distribution of exposure with a defined variation determined by the variation in daily consumption levels within the population.

Probabilistic modelling

In the probabilistic approach, both a distribution of concentration and consumption levels is used to assess the acute exposure by at randomly combining consumption and residue levels. In this way the complete diet can be addressed, including both the variability in daily consumption levels within a population and residue levels in foods. Probabilistic modelling results in a distribution of all possible exposure levels that may occur in a population. These exposure distributions provide insight in both the likelihood and magnitude of a certain level of dietary exposure. The variation in exposure is defined by both the distribution in compound and consumption levels.

acute exposure