Tier 3 probabilistic uncertainty analysis

A range of alternative methods exists at each tier, each with its own advantages and disadvantages. Although there is substantial experience with uncertainty analysis in some fields (e.g. climate change), it would be premature to make prescriptive recommendations on which methods to use in exposure assessment. For example, when discussing the use of probabilistic methods for microbial risk assessment, the former European Commission Scientific Steering Committee concluded that a quick harmonisation at the present state-of-... 

An uncertainty analysis gives the assessor the opportunity to re-evaluate the scenario, model approaches and parameters of the analysis and to consider their influence in the overall analysis. The practical impact of uncertainty analysis is illustrated within the annexed case-studies, which also clarify how uncertainty analyses follow a systematic methodology, based on a tiered approach, and consider all possible sources of uncertainty. The first step in uncertainty analysis consists of a screening, followed by a qualitative analysis and two levels of quantitative analysis, using deterministic and probabilistic data. The assessor should be aware that an uncertainty analysis cannot answer all the questions, which, moreover, may lead to new questions. 

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