Individual risk

Great Britain 1 no action required 100 - 1 further action required observing the ALARP principle (as low as reasonably nactical) 

A recent development in Germany in the field of risk limits is a proposal by the committee on hazardous materials (AGS). It specifies the risk limits given below. They concern the individual risk of death from handling carcinogenic materials [32]  

Values below these limits are acceptable. If a risk lies above them, it is tolerated observing measures specified in a catalogue as long as it lies below the limit of tolerable risk of 4 1000. 

A risk above the tolerable risk hmit is not tolerated. All risk limits refer to an entire working life of 40 years duration and continuous daily exposure. The stipulation is action-oriented and closely tied to a concept of staggered measures for risk reduction. 

In what follows several risk limits for industrial installations are given. In the U.K. the following values apply  

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Risk Estimation There are a number of risk measures which can be estimated. The specific risk measures chosen are generally related to the study objective and depth of study, and any preferences or requirements established by the decision makers. Generally, risk measures can be broken down into three categories risk indices, individual risk measures, and societal risk measures. 

Figure 26-7 is an example of an individual risk contour plot, which shows the expec ted frequency of an event causing a specified level of harm at a specified location, regardless whether anyone is present at that location to suffer that level of harm. 

The total individual risk at each point is equal to the sum of the individual risks at that point from all incident outcome cases. 

IR y = total individual risk of fatality at geographical location x,y... 

IR.i.y.i = individual risk of fatality at geographical location x,y from incident outcome case i n = total number of incident outcome cases... 

A method for graphically displaying individual risk results is use of the risk contour, or risk isopleth. If individual risk is defined as the likelihood of someone suffering a specified injury or loss, then individual risk can be calculated at particular geographic locations around the vicinity of a facility or operation. If the individual risk is calculated at many points surrounding the facility, then points of equal risk can be connected to... 

Average individual risks must be defined in context of the exposed population ... 

A. Average individual risk (exposed population) is the individual risk averaged over the population that is exposed to risk from the facility... 

Ways of combining information on likelihood with the magnitude of loss or injury (e.g., risk indices, individual risk measures, and societal risk measures)... 

Suggestions have also been made as to the number of people that are affeeted by the risk at any one time, and, in prineiple, it should be possible to link the aeeeptable level of individual risk to the number of people exposed to that risk (Niehaus, 1987). For example Versteeg (1987) provides risk levels assoeiated with three areas aeeeptable risk, reduetion desired and unaeeeptable risk, and the number of people exposed to... 

Integration of Results - consists of integration of the model with results from Steps 4, 5 and 6, to determine consequences, probabilities and range of uncertainties. Two lypes of lesulis were calculated in this study individual risk as a function of distance from the installation, and isorisk curves. Both are risk indices and are related to the probability of death from ammonia inhalation. 

The risk to an individual from operation of the facility was quantified as isorisk contours (Figure 11.4-2 - loci of equal individual fatality frequency points) and maximum individual risk vs distance curves for the most exposed individual vs distance from the site (Figure 11.4-3). Uncertainly analyses were performed (not shown). 

This system has proven to provide adequate levels of safety in the Gulf of Mexico and other similar areas where it is possible to abandon the location during a catastrophic event. In the North Sea where harsh environmental conditions exist, a different approach to safety has evolved which is based on developing a Safety Case and calculating an Individual Risk Rate (IRR) to show that the risk to any individual working in the facility is As Low As Reasonably Practicable (ALARP). 

There me two major types of risk ina. imuin individual risk and population risk. Maximum risk is defined e.xacUy as it implies, Uiat is the ma.ximum risk to an individual person. Tliis person is considered to have a 70-year lifetime of exposure to a process or a chemical. Population risk is Uie risk to a population. It is expressed as a certain number of deaths per Uiousand or per million people. For example, a fatal annual risk of 2 x 10 refers to 2 deatlis per year for every million individuals. These risks are based on very conser ative assumptions, llich may yield too high a risk. 

Variability arises from true heterogeneity in characteristics such as dose-response differences within a population, or differences in contaminant levels in tlie enviromiient The values of some variables used in an assessment change witli time and space, or across tlie population whose exposure is being estimated. Assessments should address tlie resulting variability in doses received by members of the target population. Individual exposure, dose, and risk can vary widely in a large population. The central tendency and high end individual risk descriptors are intended to capture tlie variability in exposure, lifestyles, and other factors tliat lead to a distribution of risk across a population. 

Application of pesticides Approximately 100 eaneers armually small population exposed but higli individual risks. 

Mining Waste Estimated 10-20 eaneers aiuiually, largely due to arsenie. Remote loeations and small population exposure reduee overall risk though individual risk may be high. 

Other ground water Laek of information individual risks eonsidered less tluui 10" , with rough estimate of total population risk at <1... 

Individual Risk - This provides a measure of tlie risk to a person in tlie vicinity of a liazard/accideiit, including tlie nature of the injury or otlier undesired outcomes, and tlie likelihood of occurrence. Individual risk is generally expressed in terms of a likelihood or probability of a specified undesired outcome per unit of time. For example (as indicated above), tlie... 

Societal Risk - This represents a measure of the risk to a group of people, including tlie risk of incidents potentially affecting more tlian one person. Individual risk (see above) is generally not significantly affected by the number of people involved in an incident. The risk to a person at a particular location depends on tlie probability of occurrence of the luizardous event, and on the probability of an adverse imptict at that location should the event occur. 

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... 

Risk characterization estimates tlie healtli risk associated with tlie process under investigation. The result of tliis cliaracterization is a number tliat represents tlie probability of adverse healtli effects from tliat process or from a substance released in tliat process. Tlie major types of risk include Individual Risk, Maximum Individual Risk (MIR), Population Risk (PR), Societal Risk, and Risk Indices. 

Tile average annual individual risk for the 20 people in tlie impact zones shown in Fig. 21.1.2 is obtained by dividing tlie total risk by 20. Therefore,... 

A number of calculators are available on the Internet to estimate a patient s risk of developing breast cancer. The National Cancer Institute (NCI) has an online version of the Breast Cancer Risk Assessment Tool that is considered to be the most authoritative and accurate standard (www.cancer.gov/ bcrisk-tool). The Breast Cancer Risk Assessment Tool was designed for health professionals to project a women s individualized risk for invasive breast cancer over a 5-year period and over her lifetime. 

Risk can be measured and expressed in a number of ways. CCPS s Guidelines for Chemical Process Quantitative Risk Analysis (Ref. 4) identifies three main categories of risk measure Risk Indices, Individual Risk, and Societal Risk. 

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