Risk equation

References are available which provide FAR estimates for various occupations, modes of transportation, and other activities (Kletz, The Risk Equations—What Risk Should We Run , New Scientist, May 12, pp. 320-325, 1977). 

A risk equation for nuclear power may be derived by imagining a world with a very large nuclear power plant population. All plants are identical with the same demography and meteorology. The plants are separated such that one does not affect the other. Each year, n, plants fail in the ith failure mode, causing a population dose tf,. If the effects are additive, the population dose (other risk measures could be used) is linearly proportional to the number failing (Equation 1.4-4), where ( is... 

To address this nonlinearity, it has been proposed that the risk equation be modified as shown in equation 1 4 S where the consequences are raised to the u-power to account for the effects of perception. Unfortunately, a physical basis for the value of u has not been established, but a suggested value is 1.2 (NUREG-0739), If vwere set to 1, then risk would be linear and not allow for perception. 

The cancer risk equation described below estimates tlie incremental individual lifetime cancer risk for simultaneous exposure to several carcinogens and is based on EPA s risk assessment guidelines. Tliis equation represents an approximation of the precise equation for combining risks wliich accounts for tlie joint probabilities of tlie same individual developing cancer as a consequence of exposure to two or more carcinogens. The difference between tlie precise equation and tlie approximation described is negligible for total cancer risks less tlian 0.1. Thus, tlie simple additive equation is appropriate for most risk assessments. The cancer risk equation for multiple substances is given by ... 

Historically, risk reduction strategies have been focused on the exposure side of the risk equation and in many cases have been very successful. However, there are inherent flaws in focusing primarily on controlling exposure that will be identified here. 

Green chemistry seeks to reduce or eliminate the risk associated with chemical activity by reducing or eliminating the hazard side of the risk equation, thereby obviating the need for exposure controls and, more importantly, preventing environmental... 

Through functional-use analysis, toxicological and environmental fate data on structurally similar chemicals can be applied to each member of a functional-use class. A focus on functional use not only offers commonality in perspective for chemical innovators, but also simplifies the risk assessment process. Within a given product dass, the use and exposure patterns are generally the same, with minor variability therefore, the hazard component of the risk equation becomes a... 

Cancer risk equation for mixtures Riskx = ERiski,... 

The oral reference dose (Oral RfD) is an estimate of the daily exposure of a person to a contaminant that is likely to be without appreciable risk of a deleterious non-carcinogenic effect during a lifetime (USEPA http //www.epa.gov/iris/). Oral RfD values for POP concentrations in seafood types are presented in Table 16.5, together with the daily intake of POPs from seafood consumed in Singapore. Daily intakes of POPs from seafood are below the oral RfD. The cancer benchmark concentration (Dougherty et al., 2000) represents the exposure concentration at which a lifetime cancer risk equates to one excess cancer death in one million persons. This level is defined as the public health protective concentration in the Congressional House Report to the Food Quality Protection Act of 1996 in the USA. Cancer benchmark concentrations were exceeded for DDTs, heptachlor, and PCBs (See Table 16.5). The cancer hazard ratio is the ratio of the MDI for a specific contaminant relative to the cancer benchmark concentration. The cancer hazard ratio represents the extent to which average daily exposure exceeds the benchmark concentration. The cancer hazard ratio of seafood consumption... 

Fig. 6.2. Green engineering addresses both the hazard and exposure components of the risk equation. (P/C = physical chemical properties).

Ensure that all material and energy inputs and outputs are as inherently safe and benign as possible. [This principle addresses the hazard component of the risk equation. Risk will be minimized if material and energy sources are inherently benign and safe.]... 

There are currently two approaches for setting REIs in the United States one might be considered the past approach and the other the future approach. In the first approach, the EPA s Worker Protection Standards establish interim REIs based only on acute toxicity without any consideration of the crop, the work activity or exposure. Recognizing that risk is a product of toxicity and exposure, this approach is limited in that it only takes into account one-half of the risk equation. Nonetheless, this approach is the basis for most of the REIs currently in place in the USA. In the second approach, the EPA s re-registration process (as outlined in the Worker Protection Standards) requires the development of product, crop and activity-specific REIs based on the risk associated with any given use scenario. The advantage of this approach is that it takes into account both the toxicity and exposure components of the risk equation. Such an approach is the... 

The absolute CHD risk is computed using risk equations based on the Framingham cohort in reality this means consulting a simple colour-coded chart armed with data about the patient including age, sex, smoking status, pretreatment blood pressure and plasma total and LDL cholesterol, and presence or absence of diabetes. ... 

The role of Medsafe in ensuring the safe and effective use of therapeutic products is encapsulated by its mission statement Healthy New Zealanders, by regulating medicines and medical devices to maximise safety and benefit. As a small agency with limited resources, Medscife generally applies a risk assessment-based approach to regulatory control, in order to maximise the benefit risk equation for therapeutic products. 

As the bees are buzzing a few feet from my deck chair, I question why am I not attacked Probably the bees are more interested in the nectar of flowers than in stinging me. This is where the exposure in the risk equation must be incorporated. This was previously presented as risk = hazard X exposure. The bee next to me remains just as hazardous as if it were sitting on my arm ready to sting. The difference is that with so many flowers growing in my yard and with the location of my jacket between the bee and my skin, I have additional protection drastically reducing my potential exposure. The bee and its hazard doesn t change, but the bee s access to me does, which lowers exposure and thus risk. 

Risk reduction recommendations from the analysis of pre-shipment options may be the result of any or all of the parameters of the risk equations. As described in Chapter 3, risk is a function of the consequence and likelihood of the specific transportation scenario(s) under evaluation ... 

In general, the risk is managed by plant inspectors or inspection engineers who manage the PoF with inspection and maintenance planning. They will not normally have much ability to modify the CoF. On the other hand, management and process safety personnel may desire to manage the consequence side of the risk equation [10]. 

Risk is determined by combining the PoF and the CoF. The general form of the risk equation is as follows [10] ... 

Even better is to continue to move to the left along the risk equation and to reduce the consequence of the hazard, should it occur. In the case of the pump means of doing this could include replacing the liquid with one that is less toxic or flammable, or reducing the inventory of liquid in the pumping system so as to reduce the worst-case scenario. 

The previous chapter discussed the first term in the risk equation hazard identification. This chapter discusses the analysis of the consequence and frequency terms in Eq. (14.1). 

The basic risk equation was provided in Chapter 1. It is repeated below as Eq. (15.1). 

The risk equation shows a useful way to think about risk as a combination of the nature (severity) of the hazard and the likelihood of the hazardous event occurring. 

To accommodate the difference in perception regarding risk. Equation (1.1) can be modified so as to take the form of Equation (1.2). 

Unfortunately, the one group of people who have been forgotten in the "risk" equation are the workers. Is it a "tolerable risk" for them to suffer poor health due to exposure to a toxic substance Is the "sacrifice required" (SWA, 2009a, p. 22), ultimately, their health or life ... 

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