Standards acceptable risk

Acceptable Risk. Once information is assembled concerning the characteristics of exposure and biologic effects, that information must be interpreted in terms of human safety standards. That interpretation requires that one establish a set of criteria representing acceptably safe conditions for human existence, bearing in mind that zero concentrations of environmental chemicals are unrealistic. 

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. 

In the development of regulatory standards, acconnt must be taken of acceptable risk, which will involve political considerations. Perhaps the way forward has been indicated over the past 30 years by bodies such as the American Conference of Governmental Industrial Hygienists, who have made a great contribution by publishing annually recommended standards for several hundred toxic substances. These standards have been used extensively with minor modifications by regulatory bodies in many countries. 

Figure 10.11 Risk matrix adapted from the IEC 61511 standard, indicating the accepted and non-accepted risks, as well as an intermediate field. The numbers represent the number of required IPLs together with the required SILs.

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,... 

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. 

The primary reason to oppose the filling of the car s gas tank, as it was deceptively, but accurately, described, is simply because it violates the safe practices that has been adopted as standard. The initial question, Would it be an acceptable risk cannot be answered yes based solely on the information given. One would need either to understand the physics, design standards, and routine testing that make fill-up s safe, or to rely on history, which indicates low probability of incident. Without this knowledge, one would have to be conservative and say that gas tank fill-up, as described, is not an acceptable, safe practice. 

However, it is also common to use standards to set up the infrastructure, policies, controls, or rules that mean that incidents and risks occur with acceptably rare probabilities. These standards might be described as strategic standards. For example, controls on ammonia in sewage treatment works (which are back-calculated from environmental standards) are designed to promote good fisheries in the receiving river. The intention is to reduce serious incidents to an acceptable frequency in each river because the infrastructure of sewage treatment appears to function at this level of acceptable risk. This may result in a compromise, which is essentially that standards are set up as particular types of summary statistics and not as absolute limits. 

The decision to escape from the submarine is a military-management decision that involves many considerations, which are beyond the charge and expertise of the subcommittee. SEALs are not standards or judgments of acceptable risk and must not be so construed. They are the subcommittee s best judgment based on available evidence of exposure concentrations at which submariners can continue to function in an emergency situation in an environment of a disabled submarine and be unlikely to suffer irreversible effects. Like all reports of the National Research Council, this report contains only advisory information and recommendations. 

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). 

Through some form of risks assessment it is possible to obtain a measure of the absolute or relative magnitude of the risks posed. However, there is no standard form of risks assessment methodology or a generally accepted standard for what is an acceptable risk, not are all or most of the data required for risk assessment likely to be available. Moreover, neither is it obvious, or generally agreed upon, as to how to compare fundamentally different types of risk posed by hazardous waste, such as acute versus chronic health effects and environmental damage versus health effects. 

You firmly encourage Helen to discuss this matter with her doctoi and point out to her that a dose of 300 mg is still within the standard accepted dosage range and that blood level monitoring has shown this dose to be right for her. You further remind her of the risk and consequences if her depression should recur. Because you are aware that this tricyclic antidepressant is probably extensively stored in her fat tissue you are able to provide needed reassurance that her treatment is reasonable and being safely monitored. 

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. 

Because radiation exposure can be cumulative, there are no truly safe levels of exposure to radioactive materials. Radiation does not cause any specific diseases. Symptoms of radiation exposure may be the same as those from exposure to cancer-causing materials. The tolerable limits for exposure to radiation that have been proposed by some scientists are arbitrary. Scientists concur that some radiation damage can be repaired by the human body. Therefore, tolerable limits are considered acceptable risks when the activity benefits outweigh the potential risks. The maximum annual radiation exposure for an individual person in the United States is 0.1 REM. Workers in the nuclear industry have a maximum exposure of 5 REMs per year. An emergency exposure of 25 REMs has been established by The National Institute of Standards and Technology for response personnel. This type of exposure should be attempted under only the most dire circumstances and should occur only once in a lifetime. 

For most of the products currently registered within EU only conservative standard environmental risk assessments were conducted which showed that expected risk was acceptable. Basic data requirements according to Annex II (active substances) and Annex III (formulated products) for most important groups of organisms are [2] ... 

The design standards chosen for the system defines the acceptance level. The acceptance level for a life extension evaluation will be the same as for a new design with respect to acceptable risk for the system. This means that at the end of the extended service life, and at all times during the operational phase, the integrity of the system will not be lower than what is required by the applicable design standard [11] (Figure 22.7). 

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