Decision making, consequence-only, risk

In using any risk measure, it should be remembered that risk measures, at best, are only estimates of possible event frequency and consequences All risk measurements have uncertainties. In some situations, the uncertainties can be highly significant. The fact that risk measurement is imprecise should be a consideration in any risk-based decision-making process. Chapter 5 of Reference 4 provides further discussion of uncertainty in risk decision making. 

Consequently, this document is intended not only for those who carry out the assessments, the exposure assessors, but also for those who incorporate the results into the assessment of risk, the risk assessors, and those who must rely on the final results to make decisions, the risk managers. The introduction of vocabulary and criteria is intended to facilitate communication between these groups or, in the case where one person performs one or more of these roles, to facilitate a more comprehensive thought process. It is hoped that these hallmarks of data quality can be incorporated early on in the development of exposure assessments and can allow risk assessors and risk managers to more quickly and clearly identify aspects of assessments that need more work or further justification. 

A key element in decision making will be to understand the relationship between the level of chemical exposure and the consequent risks to health or the environment. There are two main ways in which we can understand this relationship through the species sensitivity distribution (SSD) or the dose-response curve. The SSD is perhaps the more useful for environmental assessment because it integrates all species, whereas the dose response describes the cause-effect relationship for only one species. Nevertheless, the dose-response relationship could be a valuable tool for environmental assessment when the species described is either particularly sensitive,... 

System safety typically applies the qualitative risk characterization method because for a large system with many hazards, it can become cost-prohibitive to quantitatively model, analyze, and predict the risk of each and every hazard. In addition, low risk hazards do not require the refinement provided by quantitative analysis. It may be necessary to conduct a quantitative analysis only on a select few high consequence hazards. Experience over the years has proven that qualitative methods are very effective, and in most cases provide decision-making capability comparable to quantitative analysis. Qualitative risk characterization provides a very practical and effective approach when cost and time are concerns, and/or when there is very little supporting data available. The key to developing a qualitative risk characterization approach is by carefully defining severity and mishap probability categories. 

The question of whether the performance tendency results as a product of expectations and value or of probability and usefulness played a relatively important role in this connection. This question led to some stimulating numbers games (Edwards, 1968), but no conclusions could be arrived at this is no surprise, because if probability is not appropriate as a basis for decision-making in hazardous situations, the relative importance of incentives, measured in termsof expectations, cannot serve as a basis from which one can, in the usual manner, determine the intention of performance. The solution of this problem would be relatively simple if readiness to perform depended only on the evaluation of the consequences, as is, according to Jungermamnn (1982), the case for risk perception among lay persons. 

Another way of interpreting absolute risk estimates is through the use of benchmarks or goals. Consider a company that operates 50 chemical process facilities. It is determined (through other, purely qualitative means) that Plant A has exhibited acceptable safety performance over the years. A QRA is performed on Plant A, and the absolute estimates are established as calibration points, or benchmarks, for the rest of the firm s facilities. Over the years, QRAs are performed on other facilities to aid in making decisions about safety maintenance and improvement. As these studies are completed, the results are carefully scrutinized against the benchmark facility. The frequency/consequence estimates are not the only results compared—the lists of major risk contributors, the statistical risk importance of safety systems, and other types of QRA results are also compared. As more and more facility results are accumulated, resources are allocated to any plant areas that are out of line with respect to the benchmark facility. 

Competence refers to a prospective subject s ability to understand the information provided and its consequences, and make a free and informed decision in accordance with personal values. If a subject is not considered competent, a balance must be sought as to the subject s vulnerability versus the injustice of exclusion from potentially beneficial research. There is a moral preference to use competent subjects. Subjects not legally competent should only be asked to participate when the research question can only be addressed using the identified group, and the risk is minimal when there are no direct benefits. The researcher must also demonstrate how the subject s best interests are protected and the method of obtaining free and informed consent from an objective third party. If the subject should become competent during the study, consent must be obtained for continued participation. Of note, some subjects even if not legally competent may be able to ex-... 

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