they provide a basis for risk assessment of transgenic crops and will frame discussion of the case studies in subsequent chapters. Evaluation of the risks of transgenic crops requires specifying a social and environmental context for the assessment. Depending on the choice of context, different risk comparisons may become relevant. Finally, several formalizations are suggested that could help clarify this dependence on context and enable a regulatory agency to develop formal procedures to learn from its experience to improve the regulatory system.


Risk is both an intuitively easy and a technically difficult concept to understand. On the one hand, people take risks all the time in daily life, and whether explicitly or not, people are constantly balancing these perceived risks against their needs and desires. Everyone knows it is risky to drive a car, have radon leak into the basement, ice skate, play blackjack, or swim in a lake. But the personal and idiosyncratic ways people have of dealing with risk in their own lives have only tenuous connections to how society as a whole should deal with risk. Personal perceptions of risk may not reflect reality. One person might not care about the risks of eating a fish bone, but another may care so much that she will not eat any fish. Because each of us has our own way of dealing with risk, how do we agree as a society?

Volumes have been written on the technical aspects of risk. In the catalog of the National Academy Press alone, there are 184 titles related to risk. Two that are particularly relevant to this report are a 1983 publication, Risk Assessment in the Federal Government: Managing the Process, and a 1996 report, Understanding Risk: Informing Decisions in a Democratic Society. The 1983 report outlines a general approach to characterizing hazards, modeling exposure pathways, and quantifying the probability of injury. The 1996 approach argues that any attempt to assess risk involves a series of interpretive judgments and framing assumptions and suggests that democracy is best served when those affected by regulatory decision making can be as fully involved in making those judgments and assumptions as is practicably possible.

This chapter addresses risk from both perspectives. The 1983 report’s approach is followed in using science to illuminate technical understanding of the environmental risks of transgenic crops. By following this approach, however, the committee has made several implicit interpretive judgments and framing assumptions, which the 1996 report suggests. Several of these are acknowledged as implicit judgments and assumptions, and by doing so, an alternative perspective can be developed for evaluating risk analysis of transgenic crops. Before developing these par-

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