Planning for uncertainty analysis in exposure assessment

Because the objective of an exposure assessment is to characterize both the magnitude and the reliability of exposure scenarios, planning for an uncertainty analysis is a key element of an exposure assessment. The aims of the uncertainty analysis in this context are to individually and jointly characterize and quantify the exposure prediction uncertainties resulting from each step of the analysis. In performing an uncertainty analysis, typically the main sources of uncertainties are first characterized qualitatively and then quantified using a tiered approach (see chapter 4). In general, exposure uncertainty analyses attempt to differentiate between key sources of uncertainties scenario uncertainties, model uncertainties and parameter uncertainties (for definitions, see section 3.2). 

In exposure assessment, uncertainty arises from insufficient knowledge about relevant exposure scenarios, exposure models and model inputs. Each of these sources of uncertainty has factors that determine the magnitude of uncertainty and variation. For example, Mosbach-Schulz (1999) identified three factors related to the uncertainty and variability of input data  

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