etal, or visceral malformations; adverse functional outcomes; and lethality. Developmental toxicity risk assessment includes evaluating all available experimental animal and human toxicity data and the dose, route, duration, and timing of exposure to determine if an agent causes developmental toxicity (EPA 1991; Moore et al. 1995).

As discussed in the “Red Book,” risk management, in contrast to risk assessment, is the application of risk assessment information in policy and decision-making processes to balance risks and benefits (e.g., for therapeutic applications); set target levels of acceptable risk (e.g., for food contaminants and water pollutants); set priorities for the program activities of regulatory agencies, manufacturers, and environmental and consumer organizations; and estimate residual risks after a risk-reduction effort has been taken (e.g., folic acid supplementation in food). Figure 3-1 shows the NRC paradigm for risk assessment and risk management. As shown in this figure, risk characterization refers to the synthesis of qualitative and quantitative information for both toxicity and exposure assessments (EPA 1995). It also usually includes a discussion of the uncertainties in the analysis.

The following sections describe some of the specific approaches used for toxicity assessment. Four types of informational methods that can be used for

FIGURE 3-1 Risk assessment and risk management paradigm from the NRC modified for developmental toxicity risk assessments. In accordance with this committee’s deliberations, the research section now includes a two-way arrow and specifically highlights emerging research on gene-environment interaction and developmental cell-signaling pathways. The iterative feedback loop between research and risk assessment is necessary to translate new findings in biology into scientifically based risk assessments. Source: Adapted from NRC 1983.



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