Acceptable risk levels considerations

Real-world descriptions of acceptable risk levels are demonstrated by these examples. They vary considerably. 

Judgments for arriving at an acceptable risk level are influenced by many factors, and the results vary considerably across industries. Even within a company, acceptable risk levels can vary substantially by location. A country s culture also plays an important role in risk acceptability, as has been experienced by our colleagues who work in companies with global operations. Risk acceptability is also time-dependent, in that what is acceptable today may not be acceptable tomorrow, next year, or the following decade. 

For many risk simations, a combination of the risk management methods outlined in the hierarchy of controls is necessary to achieve acceptable risk levels. However, the expectation is that consideration wiU be given to each of the steps in a descending order, and that reasonable attempts wiU be made to eliminate or reduce hazards and their associated risks through steps higher in the hierarchy before lower steps are considered. A lower step in the hierarchy of controls is not to be chosen until practical applications of the preceding level or levels are exhausted. 

Systemic Socio-Technical Causation Model for Hazards-Related Incidents At least 25 incident causation models are referenced in safety literature. They present a great diversity of thinking. None of those models have achieved anything close to universal acceptance. Yet, safety professionals are obligated to have the advice they give be effective as clients take action to avoid, eliminate, or control hazards and to achieve acceptable risk levels. That advice must be based on a sound and studied thought process that takes into consideration the reality of the sources of hazards. This author builds a case in support of what he proposes for a systemic sociotechnical causation model for hazards-related incidents. 

In applying the hierarchy of controls, the outcome should be an acceptable risk level. In achieving that goal, the following should be taken into consideration ... 

In the past, three criteria for risk acceptance were developed (a) the personal acceptance of risks, (b) the social acceptance, and (c) the economic criterion. The personally accepted risk level is defined as the frequency of suffering a certain degree of injury as a result of an event, accepted by an individual. The social risk concerns the risks for the total population. Society looks at the total consequence of an event, including the number of casualties, material and economic damage, and the loss of immaterial [matters]. Generally, the consideration of social consequences in the case of safety problems is limited to the number of casualties as a result of an event. More often, the social consequence is considered the total material damage. This definition is more suitable for an economic optimization of the risk level to be... 

The measures designed to increase safety, and thus minimize risks within a material flow, are often influenced by the reliability of its individual components (transport machinery). Quantitative assessment of safety is carried out in the form of risk estimation or calculation the acceptable risk level is defined by the value of its acceptability for individual machines and machinery types. Using risk for the purpose of safety assessment of the material flow requires interdisciplinary procedures. It is crucial to correctly define a relationship between the probability of failure or a negative event occurrence and the consequence that the failure or negative event may cause. It is also essential to take into consideration various causes of negative events within the Man-Machine-Environment system as well as their consequences (location, time, person involved, duration of consequences, etc.). Appropriate statistical methods should be used for the purpose of risk (especially the probability of negative event occurrence) estimation or assessment. 

The accepted risk is a risk inferior to a level defined in advance either by law, technical, economical, or ethical considerations. The risk analysis, as it will be described in the following sections, has essentially a technical orientation. The minimal requirement is that the process fulfils requirements by the local laws and that the risk analysis is carried out by an experienced team using recognized methods and risk-reducing measures that conform to the state of the art It is obvious that non-technical aspects may also be involved in the risk acceptation criteria. These aspects should also cover societal aspects, that is, a risk-benefit analysis should be performed... 

An essential consideration in developing a risk-based waste classification system is the levels of acceptable risk that should be assumed in classifying waste. Therefore, an important concern in developing a comprehensive waste classification system is the different approaches to management of stochastic risks that have been used for radionuclides and hazardous chemicals. 

Exposure estimates that are required for risk assessment may be obtained from chemical-specific field studies, or from extrapolations from other field studies. This requires high-quality exposure data that have been obtained under conditions relevant for the exposure and use scenarios under consideration (Krieger et al, 1992 Eenske and Teschke, 1995 Krieger, 1995 Turnbull et al, 1995). For risk assessment purposes, the exposure data obtained for relevant use scenarios can be compared with an appropriate accepted exposure level (e.g. Acceptable Operator Exposure Level (AOEL)) based on the toxicological profile of the compound. 

The term binding occupational exposure limit value (BOELV) was introduced in article 3,4 of the chemical agents directive 98/24/EC. This type of Hmit is established in accordance to J 118 a of the European Treaty and is Hsted in the annex of this directive. According to the procedure for incorporation of limit values into national laws, the EU member states are required to adopt a national occupational exposure limit, which may be equal to or below the Hmit, but not higher than the BOELV. The procedure for establishing BOELV is quite complicated. Besides the toxicological properties, feasibility plays an important role. This includes technical aspects as well as considerations of the excess risk at estimated exposure levels. The acceptable-risk approach for genotoxic substances requires intense discussions on socio-economic factors between aU interested parties. 

Reasonable Risk— Exists when consumers (1) understand risk, (2) evaluate the level of risk, (3) know how to deal with the risk, and (4) accept the risk based on reasonable risk/benefit considerations. 

This chapter addresses how these two threats are encountered and coped with in the normal state as well as in cases of disturbance . Two such cases are reviewed. The first case deals with sleeping facilities and working hours, where basic features of the regulatory system have been severely tested through regulatory enforcement practices, and shows how industrial and union interests are mobilised in negotiations over economic costs, levels of protection, acceptable risk and welfare considerations. 

Determining whether a risk is acceptable requires consideration of many variables. An additional excerpt from ISO/IEC Guide 51, Section 5, helps in understanding the concept of designing and operating for risk levels as low as reasonably practicable. 

At the risk evaluation step, if the risks are found to be unacceptable, then further risk control measures win he necessary. These include measures for preventing incidents and impacts (such as implementing process safety and loss management systems for minimizing chances and consequences of hazardous material releases), and measures for responding to incidents should they occur. Cost/henefit considerations will also play a role in selecting the risk control measures for implementation. Each additional risk control measure changes the risk level, and the process of improvement continues until the risks become acceptable to the stakeholders. The involvement of the stakeholders in each step in the process is indicated in Fig. 10.5 by double-headed arrows. 

Industry has accepted a default release specification for the active substance of the label claim 5 %. This would imply that in the long run, given a label claim of 100 %, a real content between 95 % and 105 % is warranted in a pre-specified proportion of the products at release. This proportion is called producer s risk and should be between 5 % and 10 % (in the example 10 %) as is usually accepted within the Statistical Quality Control (SQC) community. The corresponding content limits are thus identical to the acceptable quality level or AQL as defined above. The producer may propose to loosen these limits, when the active substance is e.g. hygroscopic, electrostatic or otherwise difficult to handle, or when the active substance is degrading considerably within the shelf life permitted. 

A sound and workable definition of acceptable risk must encompass hazards, risks, probability, severity, and economic considerations. Also, in the following definition, it is made clear that a risk level as low as reasonably practicable must also be tolerable ... 

Although economic considerations are part of the decision making, the risk level is to be as low as reasonably practicable and acceptable. 

Acceptable Risk An acceptable level of risk for regulations and special permits is established by consideration of risk, cost/benefit and public comments. Relative or comparative risk analysis is most often used where quantitative risk analysis is not practical or justified. Public participation is important in a risk analysis process, not only for enhancing the public s understanding of the risks associated with hazardous materials transportation, but also for insuring that the point of view of all major segments of the population-at-risk is included in the analyses process. 

Consider the benefits to be achieved if a majority of organizations and safety professionals adopted the premise that hazard identification and risk assessment [are] the principle method for analyzing hazards to personnel and achieving a level of acceptable risk. It is obvious that the quoted statement defines a trend, albeit slow moving, applicable far beyond personnel considerations. 

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