Exposure mixtures calculation¶
The most common model of cumulative risk assessment is to focus on substances that belong to the same common assessment groups (CAG). Substances in such a group belong to the same chemical family and may or may not have a similar mode of action. In assessing the risk, possible interactions between substances are often ignored and, moreover, little information is available about synergistic effects at low doses. More information is needed about the combined effects of such substances, but it is impractical to investigate all possible mixtures, and therefore instruments are needed to select the most relevant substances for further investigation. This selection should not only be based on the hazard (highest relative potencies) but also on the exposure of the population to these substances. The potential risk of being exposed to chemicals in a mixture depends on the food consumption patterns of individuals in a population. A regular diet can contain hundreds of substances, so the number of combinations of substances to which an individual in a population is exposed can be numerous. The exposures mixtures module can be used to identify the most relevant mixtures to which a population is exposed.
Exposure mixtures are identified using a quantitative approach: sparse non-negative matrix underapproximation (SNMU). What mixtures predominantly determine the underlying patterns in the exposure matrix (substance x person (day))?
Figure 49 Example of co-exposure distribution (from >1 substance per individual-day, red) super-imposed on the total exposure distribution (blue).¶
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