Exposures calculation

The main goal of the exposures module is to calculate the exposure at the internal level. External exposures from dietary and non-dietary routes are aggregated at a specified target compartment (organ) in two steps:

  1. Linking dietary and non-dietary individual/individual-day exposures.

  2. Computing the (aggregated) internal exposures at the specified target compartment.

Absorption factors, just simple multiplication factors or more advanced PBK models aggregate the exposures from multiple routes into exposure at the target compartment. Currently, only dietary exposures or dietary exposures combined with non-dietary exposures are aggregated at the target compartment. Internal exposure calculation of non-dietary sources only, is yet not available but will be implemented in the future.

In cumulative internal exposure calculations two simple approaches are used to identify and select mixtures contributing to the exposure of a target population:

  1. qualitative approach: counting of co-exposure. To which combinations of substances are individuals exposed? Just the co-occurence of substances is observed.

  2. quantitative approach: maximum cumulative ratio (MCR). To what degree are mixtures more important than single substances? The relative exposure levels of the substances present in a measurement, e.g. an individual (chronic) or individual day (acute) are taken into account.

In the exposures mixtures module, two more advanced approaches are available to analyse the co-occurence of substances, the SNMU approach and a network analysis.