Critical Review of "Metals Environmental Risk Assessment Guidance for Metals" (MERAG)

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Risk assessment of metals may need specific guidance in how to handle natural background, essentiality, and long historical use of metals. It may also be necessary to take bio-availability into account. The aim of the present project was to critically review proposals on principles for risk assessment of metals (MERAG), developed by the metals industry, in co-operation with the UK Government during 2005-2006. The different MERAG proposals were reviewed by different Nordic consultancies, and their views are summarised in the report. The project was initiated and coordinated by the Nordic Risk Assessment Project (NORAP), which receives funding from the Nordic Chemicals group, a subgroup to the Nordic Council of Ministers. This review was considered urgent, in order to be prepared for a possible proposal to implement the MERAG principles within the Technical Guidance Document on Chemical Safety Assessment, which is developed for use under the REACH regulation.



Fact sheet 7: “Uncertainty analysis”, and Chapter 6 on the Background document:“Examples of probabilistic techniques and quantification of uncertainty in metal risk assessments“.

The Fact sheet 7 gives a brief introduction to techniques and methods of uncertainty and sensitivity analysis, which can be used to cast light on and quantify the uncertainties in results from e.g. a risk assessment. Uncertainty analysis aims to replace point estimates with realistic distributions representing the uncertainty and/or variability in the parameters. Sensitivity analysis aims to find out how the different input factors or parameters affect the output variables, i.e. how sensitive the output is to the different input factors. These two important analysis techniques can enable the risk manager or decision maker to see more transparently, and in terms of probabilities, how realistic the different outcomes from the risk assessment are, and for which elements of the assessment the results are most sensitive.


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