ANNEX 1 CASE-STUDY—QUALITATIVE UNCERTAINTY ANALYSIS

ANNEX 1 CASE-STUDY—QUALITATIVE UNCERTAINTY ANALYSIS 

This annex aims to illustrate qualitative uncertainty analysis through a case-study that involves estimation of exposure to a persistent, bioaccumulative and lipid-soluble group of chemicals to which humans are exposed mainly through fish consumption, which is referred to here as PBLx. Examples of appropriate communication of the outcome to various target audiences are also considered. 

This case-study addresses exposure via ingestion to PBLx in freshwater and marine water fish and shellfish. 

Components of uncertainty have been evaluated as Not Applicable (NA), Low, Medium and High in the previously described categories of level of uncertainty, appraisal of the knowledge base and subjectivity of choices (see section 5.1 of the document). 

This illustrative practical example of systematic, although qualitative, consideration of uncertainty is based on information included in chapter 3 on sources of uncertainty, in chapter 4 on the tiered approach, in section 5.1 on qualitative uncertainty and in chapter 6 on communication. It includes consensus judgements of uncertainty by a subgroup of the drafting group as a basis for illustration only. 

---

ANNEX 1 CASE-STUDY—QUALITATIVE UNCERTAINTY ANALYSIS... 

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. 

Each chapter builds on the previous ones, and so chapters should be read in the order given to ensure complete understanding of the text. A glossary of terms is provided at the end of the chapters, followed by two annexes with case-studies to illustrate both qualitative (Annex 1) and quantitative (Annex 2) uncertainty analysis. 

---