Acceptable risk levels

The most likely toxicity value to be found in the literature is the LD50 (dose lethal to 50% of the animals) for some laboratory species, usually rat or mouse. This value may be obtained by plotting on probit paper the fraction of experimental animals killed against the acute dosage. There Is seldom enough information to permit extrapolation to a dosage at which only a very small (e.g., 1%) fraction of the animals would be killed, much less to an acceptable risk level. Handy and Schindler (12), however, assum ... 

Risk characterization for non-threshold effects, e.g., for chemicals that are both genotoxic and carcinogenic, generally proceeds by comparing the acceptable risk level (Section 6.2.4) with the actual or estimated total daily intake. An alternative, new approach is the margin of exposure approach (Section 6.4). 

Finally, WHO stated that the judgment about safety, or what is an acceptable risk level, is a matter in which society as a whole has a role to play. The final judgment as to whether the benefit of adopting any of the proposed guidelines does or does not justify the risk is for each country to decide. 

I think Cotruvo was saying, let s put all of our knowledge together now and see if we can t come up with those simple tests for a number of different water supplies where we can decide whether we have an acceptable risk level without trying to decide whether this water is better than that water, because as soon as you try to decide that, what are your criteria ... 

For this type of mitigation system, probabilistic safety assessment (PSA) can be used as a tool for evaluation of and feedback to designs. Originally developed on the basis of mles and standards of engineering, resulting in a design enriched by statistical aspects and which meets acceptable risk levels for a plant in normal operation. 

If the results of a preliminary risk assessment, using a Tier 1 approach, do not generate acceptable risk levels, an examination of the physico-chemical properties of the substance, as well as the toxicological database of the product, may yield a justification for a lower dermal absorption default. A weight-of-evidence approach should be used, e.g. both the physico-chemical information and the toxicological database should support the reduced default. 

Two assessments were conducted using the US procedures with the UK food consun tion database and the DEEM-UK m model, in which a total dietary exposure estimate is calculated for all four foods at the same time. When 100% of the crop was assumed to be treated (so that probabilistic sampling was fixim the residue distributions), the resulting exposure estimates resulted in unacceptable estimates of risk. When percent crop treated was included in the assessment, the probabilistic assessment resulted in acceptable risk levels for all four commodities at the same time. 

The National Coimcil for Radiation Protection (NCRP) has identified a negligible individual risk level (NIRL) as a level of annual excess risk of health effects attributable to irradiation below which further effort to reduce radiation to the individual is unwarranted. The NCRP emphasized that this level should not be confused with an acceptable risk level, a level of significance or a standard. The NCRP recommended a level around half the natural background radiation level the final recommended NIRL level is 1 mrem this level is now called negligible individual dose (NID) level (Harley, 2001, 2008). 

In military operations, it is impossible to have zero risk, and indeed, the acceptable risk level in most cases may well be higher than that set for civilian operations. Determining the appropriate level of decontamination for a situation is the result of assessment and decision making based on all of the risks. Setting the appropriate risk levels and decontamination specifications is an area in need of Navy doctrine. Once established, that doctrine could then lead to the development of testing and performance standards to be used for field decontamination, as well as to base and long-term equipment decontamination procedures. The Navy must be able to provide doctrine, guidelines, and expertise in this area. 

Back-calculation of the potential dose or exposure concentration associated with the dose metric for a predetermined (i.e., acceptable) risk level (e.g., 1 X 10 ) or threshold level, using the human PBPK model, based on the assumption of equivalent tissue responses for equivalent dose metrics regardless of the species (Andersen et al. 1987 Krishnan and Andersen 1991b). 

Those hazards that have a risk level above the facility s acceptable risk level generate a finding which will then become a recommendation. 

An acceptable risk level for structures must be related to the basic risk accepted by all people in a society. Tliis basic risk is that which is beyond th individuals direct control. In modern times it has been the duty of govermeni through various safety controls, to regulate this hazard at an acceptable level fo society as a whole. The choice of an acceptable risk level will be affected by th special importance of structures in society as previously discussed, but must b clearly distinguished from the risk levels that an individual is prepared to tolerat when he is in control of what he is doing (for example mountaineering). 

Regularly at safety conferences and in the work of committees drafting safety standards, controversy develops over the level of risk that is acceptable. This chapter presents a thought-provoking review of the levels of risk acceptable in various enterprises (space travel, auto racing, various manufacturing and business entities) and for product safety. It also provides a practical, useable framework for safety practitioners to use in determining acceptable risk levels. 

A major emphasis of OSHA since its beginning has been the control of occupational health hazards. These high-performance compaities have given the subject priority attention. Each of the safety professionals interviewed for the third edition of this book say that their companies are operating well below worldwide permissible limits with respect to occupational health hazards. Surely, keeping occupational health hazards at an acceptable risk level is a must, even though expenditures to control health hazards can be great. 

Requirements to achieve an acceptable risk level in the design process can usually be met without great cost if the decision-making takes place sufficiently upstream. When that does not occur, and retrofitting to eliminate or control hazards is proposed, the cost may be so great as to be prohibitive. 

For workplace design, management and operations, and task performance aspects of safety, application of hazard analysis and risk assessment methods are vital to achieving an acceptable risk level. 

For many hazards and the risks that derive from them, knowledge gained by safety practitioners through education and experience will lead to proper conclusions on how to attain an acceptable risk level, without bringing teams of people together for discussion. For the more complex situations, it is vital to seek the counsel of experienced personnel who are close to the work or process. 

When required by the results of the risk assessment, alternate proposals for the design and operational changes necessary to achieve an acceptable risk level would be recommended. In their order of effectiveness, the action listing shown in The Safety Decision Hierarchy mentioned in Chapter 15, Acceptable Risk, would be the base upon which remedial proposals are made. For each proposal, remediation cost would be determined and an estimate of its effectiveness in achieving risk reduction would be given. 

The speaker gave a general response saying that a risk is acceptable if the probability of an incident occurring and the severity of harm that might result are low. Thus, the speaker defined the acceptable risk level for his company. 

Shows how some entities have, in practice, defined acceptable risk levels. 

Presents a methodology to achieve an acceptable risk level. 

The purpose of a risk management matrix is to (a) provide a logical framework for hazard analysis and risk assessment and (b) assist risk decision makers in arriving at their risk reduction and risk acceptance or declination conclusions. The implicit goal is to achieve acceptable risk levels. Several standards and guidelines now include the concepts of residual risk and acceptable or tolerable risk (e.g., ANSl/Bll TR3, ISO/IEC Guide 51, SEMI SIO—see references for full titles). 

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