Fatality estimation

Toxicology. An excellent review of the toxicity and health assessment of ethylene oxide has been compiled (233). Ethylene oxide (EO) can be relatively toxic as both a Hquid and gas. Inhalation of ethylene oxide ia high concentrations may be fatal. Estimates of lethal ethylene oxide inhalation levels in animals depend on the duration of exposure. The reported 4-h LC q values for rats, mice, and dogs are 1460, 835, and 960 ppm, respectively (234). More recent information (235) indicates that the 1-h LC q in rats is approximately 5000 ppm. 

Answer The automobile death rate is about lE-7/passenger mile. If 25,000 people evacuate 20 miles, this is 5E5 passenger miles, hence, the risk is 5E5 IE-7 = 0.05 deaths. The radiation exposure is 2.5E4 5E-4 48 = 600 person-rem. Using information from problem 4, the estimated deaths from radiation is 600 lE-4 = 0.06. About the same. The risk from radiation may be over estimated because the radiation level was measured close to the plant on the other hand, the traffic fatality estimate may be high because of police presence and slow driving. 

Exposures to relatively low concentrations of silica for a prolonged period may be capable of causing hilar node fibrosis, impairing the clearance of any silica inhaled subsequently. In one case, 30 years of exposure to <0.1mg/m led to hilar node fibrosis and calcification in an exposed stonemason subsequent exposure for 5 years to about 2 mg/m led to rapid, progressive silicosis that proved fatal. Estimates of exposure tallied with postmortem measurement of lung burden, suggesting retention of all dust deposited in the lungs over his final period of work. ... 

Early treatment of cutaneous anthrax is usually curative, and early treatment of all forms is important for I ecovery. Patients with cutaneous anthrax have reported case fatality rales of 20% w ithout antibiotic treatment and less than 1% with it. Although case-fatality estimates tor inhalational anthrax are based on iocoinpleie information, the rate is extremely high, approximately 75%, even with all possible supportive care including appropriate antibiotics. 

Combining these variables according to equation (2) yields the fatality estimates shown in figure 4. 

Toxicity of 2-Ghloroethanol. Ethylene chlorohydrin is an irritant and is toxic to the Hver, kidneys, and central nervous system. In addition, it is rapidly absorbed through the skin (73). The vapor is not sufficiently irritating to the eyes and respiratory mucous membranes to prevent serious systemic poisoning. Contact of the Hquid in the eyes of rabbits causes moderately severe injury, but in humans corneal bums have been known to heal within 48 hours. Several human fataUties have resulted from inhalation, dermal contact, or ingestion. One fatahty was caused by exposure to an estimated 300 ppm in air for 2.25 hours. In another fatal case, autopsy revealed pulmonary edema and damage to the Hver, kidneys, and brain (73). 

Risk indices are usually single-number estimates, which may be used to compare one risk with another or used in an absolute sense compared to a specific target. For risks to employees the fatal accident rate (FAR) is a commonly apphed measure. The FAR is a singlenumber index, which is the expected number of fatalities from a specific event based on 10 exposure hours. For workers in a chemical plant, the FAR could be calculated as follows ... 

If the reactor detonates, we estimate that 20 employee fatalities will occur, and 50 members of the public will be hurt. 

Consider the following example in which the worker risk from a catastrophic accident has been calculated to be 2 X 10 fatalities per year. It is possible to interpret this number in many ways, but one of the most common ways is the following there is one chance in 5000 per year that a worker will be fatally injured at the plant. However, you should be cautious when interpreting single risk estimates that are the sums of products of frequency and consequence of many accidents. The way you believe (and act) may be affected by the frequency/consequence profile that the number represents (see Sections 3.2.4 and 4.2.5.) That is, your reaction to an accident that occurs once every 100 years and kills 1 person (Risk = 10 fatalities per year) and your reaction to an accident that occurs once every 10,000 years and kills 100 people (Risk = 10 fatalities per year) are likely to be very different. 

Another approach is to use government and private mortality and injury statistics. Calculated absolute risk estimates (the probability per year of a worker being injured or killed) can be compared to those de facto worker risk standards. For example, in the United Kingdom, industry and government alike are using the fatal accident rate (FAR, see Glos-... 

Revenues. The selling price for the major product and the quantity to be sold each year must be estimated. If the product is new, this can be a major study. In any case, input is needed from sales, transportation, research, and any other department or individual who can increase the accuracy of the revenue data. The operating costs may be off by 20% without fatal results, but a 20% error in the sales volume or price w ill have a much larger impact. Further, the operating costs are mostly within the control of the operator, while the sales price and volume can be... 

Although the consequences of the high-risk accident sequences may vary from one PSA to another, all PSAs attempt to evaluate realistically, the consequences of hypothetical accident sequences. Expending on the scope of the PSA, these evaluations may include an estimation of the number of latent cancers, the number of immediate fatalities, the probability of core damage, or a number of other consequence measures. 

The objective is to estimate, numerically, the probability that a system composed of many components will fail. The obvious question is, "Why don t you just estimate the failure rate of the system from operating experience " There are three reasons IJ the system may not exist, so new data are not available, 2) the injuries and fatalities from the developmental learning experience are unacceptable - the risk must be known ahead of time, and 3) by designing redundancy, the probability of the system failing can be made acceptably remote in which case system failure data caimot be collected directly. The only practical way uses part failure statistics in a system model to estimate the system s reliability. 

Eisenberg et al. (1975) developed estimates of fatalities due to thermal radiation damage using data and correlations from nuclear weapons testing. The probability of fatality was found to be generally proportional to the product where t is the radiation duration and 7 is the radiation intensity. Table 6.7 shows the data used to develop estimates of fatalities from thermal radiation data. 

A single-number index value representation A point estimate of fatalities/10 exposure hours... 

An estimate of peak individual risk of FAR A number representing tire estimated average number of fatalities per unit time A single-value representation of consequence... 

The reader should note tliat since many risk assessments have been conducted on the basis of fatal effects, there are also uncertainties on precisely what constitutes a fatal dose of thennal radiation, blast effect, or a toxic chemical. Where it is desired to estimate injuries as well as fatalities, tlie consequence calculation can be repeated using lower intensities of exposure leading to injury rather titan dcatli. In addition, if the adverse healtli effect (e.g. associated with a chemical release) is delayed, the cause may not be obvious. Tliis applies to both chronic and acute emissions and exposures. 

Quantitative risk analyses usually produces single-number estimates. These may be used to compare one risk with another in a quantitative sense or occasionally employed in an absolute sense. One of the most popular risk policies employed by industry is tlie FAR Concept (Fatal Accident Rate). FAR represents tlie number of fatal accidents per 1,000 workers in a working lifetime (10 lir), where a working lifetime is assumed to be approximately lO lirs. An acceptable FAR (by industries standards) is 4.0. 

Depression is a common, serious, sometimes fatal illness that is chronic and recurrent in nature, impairs family life, reduces social adjustment, and is a burden on the community (Klerman and Weissman, 1992). This disease chronicity magnifies hoth its societal impact and its economic burden. It has been estimated that more than 17% of the disability associated with mental disorders is the result of depressive disorders (Rosenbaum and Hylan, 1999), and that the global burden of depression, measured in terms of disability-adjusted life years, will rank second only to ischaemic heart disease by the year 2020 (Murray and Lopez, 1996). 

Cost-benefit analysis also requires a determination of the costs incurred from incident-related fatalities. Reduction in individual risk (fatalities per year) is a key component in risk associated with buildings in process plants. One method of determining the cost of fatal accidents is to estimate the amount of money that society might perceive as reasonable compensation in the event of a fatal accident. 

For nuclear waste disposal, in a site such as Yucca Mountain, if the maximally exposed individual receives the proposed annual limit of 0.15 mSv, present estimates (based on the linearity hypothesis) suggest a 0.00 1 % risk of an eventual fatal cancer. The maximum dose is reached only if the wastes are dissolved in a small volume of water, and therefore only a limited number of people would receive this dose. If this number were as high as 1000, the implied toll for Yucca Mountain neighbors would be one cancer fatality per century per repository site.19 This toll would not start for many centuries, when the waste canisters begin to fail, and it not unreasonable to expect that cancer prevention and treatment will be much improved by then. Ignoring this prospect, and assuming many repositories and some doses above the prescribed limit, it still appears that the expected toll would be well under a thousand deaths per century. 

Kimura K, Hasegawa M, Matsubara K, et al. 1994. A fatal disaster case based on exposure to hydrogen sulfide - an estimation of the hydrogen sulfide concentration at the scene. Forensic Sci Int 66 111-116. 

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