Definition of risk

The term risk as used in this Report refers to the probability of harm, combined with the potential severity of that harm. In the context of impacts on human health resulting from disposal of hazardous waste, risk is the probability of a response in an individual or the frequency of a response in a population taking into account (1) the probability of occurrence of processes and events that could result in release of hazardous substances to the environment and the magnitude of such releases, (2) the probability that individuals or populations would be exposed to the hazardous substances released to the environment and the magnitude of such exposures, and (3) the probability that an exposure would produce a response. For example, risk refers to the probability that a member of the public living near a waste disposal site will develop a certain type of cancer as a result of emplacement of hazardous substances at the site. When expressed as a probability, risk is a number between zero and one, without units. In this Report, all values are risks to an individual over a normal lifetime. Risk can be calculated for individual radioactive and chemical substances in waste and for specific pathways by which release and exposure might occur. These component risks can be combined to yield an overall risk that arises from disposal of waste. 

Different measures of response can be used in estimating risk. For example, risk could refer to the probability of occurrence (incidence) of a particular response or the probability that death will result. The probabilities of these two endpoints will rarely be the same, because some adverse effects will be cured by medical treatment or the receptor will die by some other means before death is caused by exposure to a hazardous substance. 

In environmental health, risk is typically expressed in such terms as the estimated incremental lifetime cancer risk to an individual 

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To convert the words of the second definition of risk into mathematics, let chance" be probability, "loss" be consequences, and... 

Much of the initial development of Gaussian modeling and definition of dispersion paramenters was done during and after World War I in addressing the problem of poison gas dispersal. These studies involved the definition of risk factors, such as exposure and dose. The next intensive development effort came during and after World War II with the nuclear weapons program. 

A consensus-derived definition and classification system for ARF has been proposed and is being validated (Fig. 75-1). Components of the system include both GFR and UOP plus two clinical outcomes. Definitions of risk of dysfunction, injury to and /ail ure of the kidney, loss of function, and end-stage kidney disease are included in the RIFLE acronym. 

Defining the Risk to Be Managed For the purposes of an SVA, the definition of risk is shown in Fig. 23-65. The risk that is being... 

Stating a definition of safety is often overlooked in safety research, and the concept of safety is not as obvious as it may seem, often being associated merely with the absence of risk. Literature contains many different definitions of risk (see for different examples of definitions Adams (Adams, 1995) Lees (Lees, 1996), IEC 61508 (IEC 61508, 2000)). The IEC (IEC 61508, 2000), defines risk as a combination of the probability of an occurrence of harm and the severity of this harm. Harm is... 

The definition of risk from Chapter 1 is used to set up an analysis tool to find a possible link between Sis and recent accidents. The following sub-Section will therefore introduce this analysis tool before analysing current safety indicators and accidents. 

Looking forward with hope to the continued development and use of the risk assessment framework, and of those scientific disciplines that supply the data and knowledge necessary for its use, I propose the following, perhaps overly grand, definition of risk assessment, in an attempt to ensure its applicability not only to the types of problems that have been the principal subjects of this book, but to all those of public health concern. 

The definition of risk characterization in terms of the TGD differs somewhat from that of the OECD/IPCS given in Section 8.1. According to the TGD (EC 2003) ... 

Apart from changing the definition of a medicinal product, the definition of risks related to use of the medicinal product has also been changed. The definition now has four components - in addition to the current definition which defines risk to public health in terms of the quality, safety and efficacy of the product, the revised legislation requires an assessment of any undesirable effects on the environment from use of the product. 

Article l(28)a of Directive 2004/27/EC defines the risk-benefit balance as an evaluation of the positive therapeutic effects of the product in relation to the risks to patients or public health. The environmental component of the definition of risks is excluded from the risk-benefit balance. Under the new legislation, the risk-benefit balance is considered as part of Article 23 (which enables the competent authority to continuously assess the risk-benefit balance by requesting relevant data from MAH), and Article 104 (relating to the submission by MAH of PSURs). 

Risk assessment of chemicals does not, in practice, estimate the incidence and severity of the adverse effects likely to occur in the human population or environmental compartment due to actual or predicted exposure to a substance — the definition of risk characterization in Article 2 of Directive 93/67/EEC. The assessment process hinges on being able to say that there is a threshold below which the chemical has no adverse effects, in other words on being able to derive a no-effect level. Recent debates, discussed later, challenge the idea that there normally is such a threshold. 

Risk assessment is the definition of risks, potential risks, and the risk-benefit equations necessary for the regulation of toxic substances. Risk assessment is logically followed by risk communication and risk management. 

Given the definition of risk indexes (Rid in Equation 1.1 or 1.2 and assuming that risks from exposure to the different hazardous substances in waste are additive, waste classes are defined by the requirement on each waste class and associated disposal system that ... 

There is no universally accepted definition of "risk assessment." Some define it narrowly to mean only the identification of a hazardous substance. Others interpret it to mean the full range of activities, including the risk-benefit analysis and the economic considerations used to make a regulatory decision. 

The definition of risk is the probability times the consequences (Figure 20.1). So the probability of an immune response is not synonymous with its risk. A high risk can be associated with a relative high probability, but also with a low probability if the consequences are severe. For example, the probability of an immune response to epoetin is rather low, but one of the consequences, antibody-induced severe anemia, is severe [3], This makes the risk of immunogenicity of epoetins relatively high. 

Fundamental differences in the scientific community arise with regard to the precise definition of risk. This reflects a long-standing philosophical divide between positivism and relativism. More recently, the definition of risk has been subject to debate between realists and constructionists. 

Identifying a hazard is only a small part of the risk assessment process. Hazard must be differentiated from risk. Assessing risk involves an analysis of the likelihood that adverse effects to human health or the environment after exposure to a chemical may occur. For risk management, exposure assessments therefore play equal (if not more) important parts as evaluations of hazard. The following sections discuss how toxicology, exposure assessments, and risk characterisations contribute to the central scientific definition of risk as probability versus consequence [93-95]. 

Conversely, if the supplier s Quality Management System is very well written and there is documented evidence that the supplier adheres to it, the definition of risk levels might be relaxed a bit in the Function Risk Assessment. If the supplier s own acceptance testing is well documented and thorough, the Validation Plan should document the intent to reference some of the supplier testing in lieu of internal tests. It is not necessary to specify exact tests to be used at this point that can wait until the test plans are being prepared later on. 

Uncertainties inherent to the risk assessment process can be quantitatively described using, for example, statistical distributions, fuzzy numbers, or intervals. Corresponding methods are available for propagating these kinds of uncertainties through the process of risk estimation, including Monte Carlo simulation, fuzzy arithmetic, and interval analysis. Computationally intensive methods (e.g., the bootstrap) that work directly from the data to characterize and propagate uncertainties can also be applied in ERA. Implementation of these methods for incorporating uncertainty can lead to risk estimates that are consistent with a probabilistic definition of risk. 

Kaplan S and Garrick BJ (1981) On the quantitative definition of risk. Risk Analysis 1 11-27. 

Manger K, Manger B, Repp R, et al. Definition of risk factors for death, end stage renal disease, and thromboembolic events in a monocentric cohort of 338 patients with systemic lupus erythematosus. Ann Rheum Dis 2002 61 1065-1070. 

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