Risk characterization paradigm components

Risk assessment An empirically based paradigm that estimates the risk of adverse effects) from exposure of an individual or population to a chemical, physical or biological agent. It includes the components of hazard identification, assessment of dose-response relationships, exposure assessment and risk characterization. 

This chapter will address the implications of the data presented in previous chapters for assessing the risks from environmental chemical exposures. WHO/IPCS has defined risk assessment as an empirically based paradigm that estimates the risk of adverse effects from exposure of an individual or population to a chemical, physical, or biological agent. As shown in Figure 21, it includes the components of hazard identification (Is there an adverse effect ), dose-response assessment (How severe is it ), exposure assessment (What is the level of exposure ), and risk characterization (What is the risk ) (NRC, 1983 IPCS, 2000). 

Identifying dose-response relationships is an important component of any risk assessment. This process establishes the exposure levels that produce effects, as well as those that produce no effects. As noted in Box 2, it is important to characterize what data were used, what model was employed to develop the dose-response curve(s), and whether chemical-specific information is available to support the observed dose-response relationship. While the risk assessment paradigm shown in Figure 21 separates hazard... 

Risk assessment is a process where the magnitude of a specific risk is characterized so that decision-makers can conclude whether the potential hazard is sufficiently great that it needs to be managed or regulated, reduced or removed. The National Research Council (NRC, 1983) of the National Academy of Sciences (NAS) first described the process of human health risk assessment, with an update in 1994 and 1996, as a four-component paradigm (i.e., hazard identification, dose-response assessment, exposure assessment, and risk characterization), with risk communication as a fifth area of study. The first four components are described briefly below. 

Developing an objective assessment of the hazard that copper poses to humans and the environment depends on an intimate understanding of the bioavailability. Bioavailability, which is defined as the extent to which the metal is taken up by the organism upon exposure, depends on the species of the metal or metallo complex and/or how easily it can be transformed to a more or less bioavailable species. The key components of the environmental risk assessment paradigms include problem formulation, analysis (which includes both exposure and effects analysis) and risk characterization (WHO 1998). 

As described in a highly referenced document (NRC, 1983), important components of this process include hazard identification, assessment of exposure and dose-response relationships, and characterization of the risk. Uncertainty factors are built into the risk assessment process to account for variations in individual susceptibility, extrapolation of data from studies in laboratory animals to humans (i.e. interspecies variation in toxicokinetics), and extrapolation from high-dose to low-dose exposures. In the case of the association between exposure to chemicals and drugs and autoimmunity or autoimmune diseases, much of the information needed to evaluate risk in the context of the traditional United States National Research Council paradigm is not available. The following represents a discussion of issues in chemical-induced autoimmunity relevant to the use of existing data and data needs in risk assessment. 

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