Definition of Risk Assessment

If one conducts a literature search on the term risk assessment, a lengthy list of publications on a range of topics will be produced (NAS/NRC, 1983 1994 Paustenbach, 1995), because this term has been used to describe estimates of the likelihood of a number of unwanted events. These include, for example, industrial explosions, workplace injuries, failures of machine parts, natural catastrophes, injury or death as a result of voluntary activities or lifestyle, diseases, and death from natural causes. 

For the purposes of this Report, a risk assessment is a written document wherein all the pertinent scientific information regarding the risk that arises from disposal of hazardous waste is assembled, critiqued, and interpreted. The goal of the assessment generally could be to calculate the likelihood of responses in humans, aquatic or terrestrial biota, or ecological systems that arise from disposal of hazardous wastes. In this Report, however, the focus is on assessment of health risks in humans (see Section 2.2.6). The magnitude of the risk depends on both the potency of hazardous substances and the amount of exposure, which is a function of the duration of exposure and the concentrations of hazardous substances. 

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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. 

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. 

A special case that falls under the present definition of risk assessment methods is provided by the methods for analysis of dioxins and related compounds included in the calculation of toxic equivalent quantity (see Section 11.4.1). 

Title X, unlike the LBPPPA, provides for the use of a risk assessment within a narrow meaning of having lead-painted surface inspections in terms of the Act s hazard definitions. Here, risk assessment does not refer to the scientific definition of risk assessment as an applied discipline drawing upon multiple academic branches of science and requiring application of principles and practice as set forth in, for example. Part 4 of this monograph. 

A very simple definition of risk assessment is Assessing the risk that may arise from hazards (Successful health and safety management, hsg65,1997). The identification of priorities based on the severity of loss-producing events is established. 

There are many definitions of the word risk. It is a combination of uncertainty and damage a ratio of Itazards to safeguards a triplet combination of event, probability, and consequences or even a measure of economic loss or human injury in terms of both the incident likelihood and tlie magnitude of the loss or injuiy (AICliE, 1989). People face all kinds of risks eveiyday, some voluntarily and otliers involuntarily. Tlierefore, risk plays a very important role in today s world. Studies on cancer caused a turning point in tlie world of risk because it opened tlie eyes of risk scientists and healtli professionals to tlie world of risk assessments. 

The technique of risk assessment is used in a wide range of professions and academic subjects. Accordingly, in this introductory section some basic definitions are necessary. 

Hazard is commonly defined as the potential to cause harm . A hazard can be defined as aproperty or situation that in particular circumstances could lead to harm (Smith et al., 1988). Risk is a more difficult concept to define. The term risk is used in everyday language to mean chance of disaster . When used in the process of risk assessment it has specific definitions, the most commonly accepted being The combination of the probability, or frequency, of occurrence of a defined hazard and the magnitude of the consequences of the occurrence (Smith et al., 1988). 

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). 

If the assessment is to be probabilistic, the risk assessor and risk manager should consider together how this influences the definition of the assessment endpoint. Suter (1998) suggests 5 questions for the risk assessor to ask the risk manager to help define the assessment endpoint ... 

Essential prereqnisites for a probabilistic risk assessment are a well thought-out problem formulation and a clear definition of the assessment endpoints. The probabilistic approach according to its very natnre aims at making predictions on quantities or the occurrence of certain events. Snch qnantities and events must be specified precisely such that, at least in principle, there is no doubt on what the quantity is or whether the event happened (Morgan and Henrion 1990). 

Formulating the assessment problem well is an essential foundation for risk assessment. The workshop considered how the use of probabilistic models and uncertainty analysis affects problem formulation and its main components the integration of available information, definition of the assessment endpoint, specification of the conceptual model, and planning of the analysis phase. 

There is another use of risk assessment that is emerging. When an action or exposure affecting the risk of cancer has occurred, how can the subsequent risk of disease be apportioned among its various possible causes If such apportionment is definite, the word attribution may then be applied to the risks (Rail et oL, 1985). 

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. 

The fundamental question of risk assessment for potential human carcinogens requires definition of substances that exceed an evidentiary threshold. Once the scientific evidence establishes a substantial basis for conclusion of known or potential human cancer, it is then in order to determine a procedure for risk quantification. Quantitative risk assessments must always be read with the qualitative evidence of the likelihood of carcinogenicity. 

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. 

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]. 

For decades, risk assessors have essentially considered the effects on humans from exposure to individual substances. Standardized approaches have been developed along with research to improve this methodology and its reliability. The increased complexity of risk assessments and the numerous organizations performing them have led to the use of varied risk assessment concepts. Two main concepts—risk and hazard—were used earlier in different ways, creating confusion to the regulators and the public. To facilitate consistency, the National Academy of Sciences (NAS) recommended key definitions in... 

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. 

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