ABSTRACT
Since the 1980s, risk assessments have become an imponant tool used by industries and state and federal agencies to systematically identify and characterize potential public health hazards resulting from exposure to environmental compounds. The use of risk assessment has grown, at least in part, because it provides a common framework for negotiation and decision making and attempts to create objectivity in judgment (Hornstein, 1992). A framework for regulatory decision making that utilizes the characterization of risk (Fig. 1) was proposed in the early 1980s (Calkins et al., 1980). This framework was used by the National Research Council to establish its "redbook" risk assessment principles (NRC, 1983) wherein the goal of risk characterization is achieved through a combined qualitative and quantitative analysis of risk. The most recent version of the NRC framework is shown in Figure 2 (NRC, 1994). Qualitative information used in risk analysis includes the strength of evidence for an adverse outcome, the nature of the outcomes resulting from an exposure or situation, exposure routes, the identification of sensitive populations, information on areas of uncertainty (and their influence on the risk estimate), and descriptive information on other factors that influence the risk estimate. Quantitative information includes exposure assessments, estimates of the potential magnitude of the risks, and uncertainty information regarding the risk estimates.
