Non-dietary exposures uncertainty

In an aggregate exposure assessment, dietary and nondietary data are combined into an aggregate exposure distribution. The nondietary data are supplied in table NonDietaryExposures. In an uncertainty analysis, MCRA provides two ways to assess the uncertainty:

1. the uncertainty set approach

2. the bootstrap algorithm.

When table NonDietaryExposuresUncertain is not supplied, the nondietary data in table NonDietaryExposures is resampled and the bootstrapped sets are used in the uncertainty run. More precisely, in each outer loop of the 2D Monte Carlo, within each nondietary survey (multiple surveys may be supplied), the nondietary individuals are resampled. Each individual represents a nondietary exposure set containing dermal and/or oral and/or inhalation exposure values for multiple substances. Bootstrapping is the default behaviour when the NonDietaryExposuresUncertain table is missing. When uncertainty distributions supplied in this table represent sampling uncertainty (individual exposure sets are repeatedly sampled using the same nondietary exposure generator without changing the input parameters), then bootstrapping the data performs equally well and is more efficient.