Risk assessment expert judgments

In the authors opinion, even if imperfect, the CLL approach is preferable to apply for ecosystem risk assessment than a qualitative EcoRA based mainly on expert judgment. 

Probabilistic methods can be applied in dose-response assessment when there is an understanding of the important parameters and their relationships, such as identification of the key determinants of human variation (e.g., metabolic polymorphisms, hormone levels, and cell replication rates), observation of the distributions of these variables, and valid models for combining these variables. With appropriate data and expert judgment, formal approaches to probabilistic risk assessment can be applied to provide insight into the overall extent and dominant sources of human variation and uncertainty. 

The toxicity exposure ratio approach, rather than a more rigid standard setting approach (Section 8.2.2), allows greater room for expert judgment because the size of an overall assessment factor is not fixed. Furthermore, this approach can be readily applied to substances for which limited data are available. The risk assessor can decide how wide the MOS should be in the light of the data available. 

Expert judgment is required to weigh these individual parameters on a case-by-case basis. The approach used should be transparent and a justification should be provided by the risk assessor for the conclusion reached. It should be recognized that these parameters are parallel to those being considered in the evaluation of the assessment factors to be apphed in the estabhshment of a tolerable intake (Chapter 5). It should be noted that the first edition of the TGD (EC 1996) did not provide any quantitative guidance on the minimal size of the MOS. 

When human data are unavailable or limited, the risk assessment must be based on extrapolation from animal data, short-term tests, and other information. Under these circumstances, the evidence must be weighed with reference to its predictive accuracy, and expert judgment must be exercised in selecting the appropriate model for extrapolation toman. 

Just when new information about the effects of chemical exposures was provoking new questions about the scientific bases of risk assessment, community-based environmental groups were coming to realize that risk assessment was not a value-neutral scientific tool, but was in fact quite political, in the sense that it could be used to reach predetermined conclusions through the deliberate choice of assumptions, uncertainty factors, and judgments. Furthermore heavy reliance on risk assessment had the effect of placing decisions in the hands of experts instead of the hands of the people who would be affected by the decisions. 

NIOSH develops most RELs from qualitative and semiquantitative risk assessments, using expert judgments based on comprehensive reviews of relevant scientific literature. However, a number of RELs have been based on limits of sampling capabilities or on limits of technological feasibility. In response to an OSHA rule on carcinogens (29 CFR 1990.103), NIOSH had subscribed to a policy calling for no detectable exposure levels for proven carcinogenic... 

Expert judgment is required in many areas of risk analysis. Probabilistic Safety Assessment (PSA) makes no exception. 

HSE assessments have a long tradition within the oil-and gas industry. These assessments use a wide range of methodologies, from the strict quantitative methods such as QRA (Quantitative Risk Analysis) and FMECA (Failure Mode Effect and Criticality Analysis) to the more qualitative methods such as HAZOP (HAZard OPerability analysis). Most methods combine qualitative and quantitative data and approaches. For example, an FMECA basically uses generic failure data, expert judgments are likewise important. 

The main objective for HSE assessments or risk analysis on technical safety is to calculate an overall risk factor or to ensure a safe design. It has, however, been considered that the involvement of the operational personnel given input to the failure rates or expert judgments has a value in itself. The involvement in a HAZOP, for instance, gives enhanced risk perception and important reflection on safety issues. 

The FSA approach is a standardized holistic approach, and consists of five steps (IMO 2002) 1) Hazard Identification, 2) Risk Assessment, 3) Estabhsh Safety Measures, 4) Cost-Benefit Assessment, and 5) Recommendation for decision making. It is mandated that in order to be consistently appUed by different parties, the process must be clearly documented and formally recorded in a uniform and systematic manner (IMO 2002). In general, the availability of suitable data for all steps in the analysis is vital. If not readily available, these may be estimated through models, expert judgment and simulations. 

The developments are linked to risk influencing factors (RIFs) in a risk influence model. Expert judgment will then be used to assess the risk contribution from each RIF to the total risk, thereby providing a means for focusing risk reducing measures. 

Cooke, R.M., Goossens, L.H.X, 2007. Expert judgment elicitation for risk assessments of critical infrastructures. Journal of Risk Research, 7(6), pp. 643-656. 

It is emphasized that the results presented in this paper are preliminary and based on a combination of available information from risk assessments and expert judgment. Further detailed risk studies are necessary to come to a more detailed and accurate understanding of the level of fatality risks from floods throughout the Netherlands. The outcomes of the FLORIS project are expected by the year 2011. These outcomes will include estimates of the spatial distribution of individual risks. 

Risk assessment involves a combination of various risks based on different types of consequences. Information on the historic record of hazard events, frequency-magnitude and triggering mechanisms provides additional insight for the recognition of risk sites and risk level. Further parameter calibration and expert judgment are required for practical risk management. 

PrHA depends on expert judgment for assessment and ranking of risks and their prioritization. 

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