Hazard acceptable risk

Risk is the potential danger presented by a hazard. Acceptable risk is the amount of potential mishap risk (i.e., danger) presented by an identified hazard that is allowed to persist without further risk reduction action. In system safety, risk acceptance is the formal process of accepting the risk presented by an identified hazard, thereby acknowledging its existence and the actions taken to control it. 

The remaining step in the hazard identification and risk assessment procedure shown in Figure 1 is to decide on risk acceptance. For this step, few resources are available and analysts are left basically by themselves. Some companies have formal risk acceptance criteria. Most companies, however, use the results on a relative basis. That is, the results are compared to another process or processes where hazards and risks are weU-characterized. 

Acceptable risk Accident (sequence) Acute hazard... 

Risk analysis A methodical examination of a process plant and procedure that identifies hazards, assesses risks, and proposes measures that will reduce risks to an acceptable level. 

As it has been shown in this chapter knowing the concentrations of chemicals in the environment is a key aspect in order to carry out meaningful hazard and risk assessment studies. Predicting concentrations of chemicals can serve as a quick and robust way to produce an acceptable screening level assessment however if further precision is desired, the complexity of real environmental scenarios can make it a cumbersome and unaffordable task. Models improvement requires not only refining their computation algorithms but also and more important, implementing new inputs and processes in order to better describe real scenarios. 

Accepted risk The risk is considered tolerable for a given activity by those responsible for managing or regulating the operation of a hazardous facility. The term acceptable risk has often been used, but this inevitably raises the question, Acceptable to whom Tweeddale... 

Complete a hazard and risk assessment to determine if it is acceptable to commit responders to the site. 

Haynes alloy 25 (L605), composition of wear-resistant alloy, 7 22 It Haynes alloy 188, composition of wear-resistant alloy, 7 22 It Hayward Tyler agitator, 1 739 HAZARD I method, 11 449 Hazard acceptance, 13 170 Hazard Analysis and Critical Control Point (HACCP) protocol, 15 260 Hazard analysis and risk assessment,... 

Hazards of Materials Involved Accept risk (do nothing)... 

Reduction of Inventories Advancements in process control and changing acceptable risk standards may have removed the initial justification for large inventories of hazardous raw materials or products. For example, tight quality control of on-time deliveries of hazardous raw materials may allow for a one or two day supply on hand versus a one- or two-week supply. 

The conditions under which the drug is used need to be estimated as do acceptable residues linked to the level of acceptable risk to the consumer. The acceptable level of risk, which is determined in theory at the risk management stage, has already been expressed in terms of residues by the ADI under hazard characterization. Moreover, the elements considered for hazard identification, hazard characterization, and exposure assessment make it possible, for a given form of utilization of a particular substance, to establish a profile of residues in animal tissues and to associate this with a profile of consumer exposure. Comparison of this consumer profile and ADI indicates whether the mode of utilization of the substance is acceptable or not. Analysis of the different results of residue content in animal products then provides an indication of level of residues in one or several animal tissues, making it possible to differentiate between veterinary drug applications that do or do not permit compliance with the ADI. 

Waste that exceeds concentration limits for exempt waste would be classified as low-hazard if it poses no more than an acceptable (i.e., barely tolerable) risk to a hypothetical inadvertent intruder at a dedicated near-surface disposal facility for hazardous wastes, with the important condition that an acceptable risk or dose used to determine low-hazard waste should be substantially higher than a negligible risk or dose used to determine exempt waste. 

To the extent that risk is used as a basis for waste classification, it is not used consistently. Different values for acceptable risk are assumed for different hazardous waste disposal situations. In addition, a variety of surrogate measures (e.g., ingestion toxicity, total radioactivity) having varying relationships to risk have been used to classify wastes. 

The waste classification system developed in this Report includes a general class of exempt waste. Waste in this class would contain sufficiently small amounts of hazardous substances that it could be managed in all respects as if it were nonhazardous (e.g., as household trash). NCRP intends that exempt materials could be used or disposed of in any manner allowed by laws and regulations addressing disposition of nonhazardous materials. However, exempt waste would not necessarily be exempt for purposes of beneficial use without further analysis of the risks associated with anticipated uses. Materials could be exempted for purposes of disposal or beneficial use based on similar considerations of acceptable risk. However, based on differences in exposure scenarios for the two dispositions, limits on the amounts of hazardous substances that could be present in exempt materials intended for beneficial use could be substantially lower than the limits for disposal as exempt waste. Thus, disposal may be the only allowable disposition for some exempt materials based on considerations of risk. In addition, some exempt materials may consist of trash, rubble, and residues from industrial processes that would have no beneficial uses and must be managed as waste. 

Section 7 then addresses the implications of the recommended risk-based waste classification system. By assuming key parameters (e.g., values of acceptable risk, characteristics of exposure scenarios) and applying the system to a variety of example waste streams, the question of how existing wastes would be classified in the new system is investigated. This Section also summarizes the legal and regulatory ramifications of the proposed hazardous waste classification system. 

A proper reconciliation of the radiation and chemical paradigms for risk management is important to the development of a comprehensive and risk-based hazardous waste classification system. In particular, the proposed waste classification system developed in Sections 6.2 and 6.3 of this Report is based fundamentally on the concept that an acceptable risk generally can be substantially greater than a negligible risk. This distinction is used to define different classes of waste that pose an increasing hazard. 

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. 

Low-Hazard Waste - Risk from disposal in dedicated near-surface hazardous waste facility would not exceed acceptable (barely tolerable) levels... 

Establishing an acceptable risk or dose. There also are a number of precedents for establishing an acceptable (barely tolerable) risk or dose of substances that cause stochastic responses for the purpose of classifying waste as low-hazard or high-hazard. For radionuclides, the annual dose limit for the public of 1 mSv currently recommended by ICRP (1991) and NCRP (1993a) and contained in current radiation protection standards (DOE, 1990 NRC, 1991) could be applied to hypothetical inadvertent intruders at licensed near-surface disposal facilities for low-hazard waste. This dose corresponds to an estimated lifetime fatal cancer risk of about 4 X 10 3. Alternatively, the limits on concentrations of radionuclides in radioactive waste that is generally acceptable for near-surface disposal,... 

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