uncertainty in risk characterization and risk management, it is important to consider how individuals and societies value uncertain adverse consequences. The committee expects such valuations to be expressed in terms of relative preferences, economic preferences, or ethical constraints. One issue that must be considered when there are large uncertainties in risk estimates is how to communicate this information to the affected public. The committee has found that it is often difficult to find the appropriate language for communicating and discussing uncertainties among ourselves. Thus, it is concerned that this difficulty will be amplified significantly when there is a need to communicate information about uncertainties to the less technically oriented community groups that must make decisions based on relative-risk estimates.

Another National Research Council report, Improving Risk Communication (National Research Council 1989), has reviewed a number of issues related to risk communication. That report provides some discussion regarding the problems of uncertainty and variability in risk communications. It is suggested that it is dangerous to quantitatively describe the uncertainties in risk messages. It is generally not possible to describe the complexity of the uncertainty analysis. However, it should be made available in ancillary documents. A key goal of their recommendations is to help audiences distinguish areas of scientific agreement amid what may appear as vast areas of policy disagreement. Careful delineation of existing scientific uncertainty is that it gives audiences a sense of the degree of scientific consensus and allows them to distinguish minor from major uncertainties. Thus, the description of uncertainties is both an essential and difficult part of the communication of risk to the public.

Communicating successfully with the public and with water utilities concerning the uncertainty of the risks of radon in air and in water, as well as the uncertainties regarding the likely benefits of risk-reduction strategies will require involving those parties in the process much earlier than was done previously. Risk managers have previously viewed risk communication as a one-way, temporal educational process in which experts pronounced and the audience listened and learned. An unsuccessful risk communication effort was blamed on audience failure to assimilate the information and act appropriately.

That unilateral approach is being replaced by a multilateral one as agencies with a communication mission work to involve the audience in planning and execution. Serving as an important catalyst for this change was the previously mentioned National Research Council (1989) report which declared "risk communication should be a two-way street," between experts and various groups, that should exhibit a spirit of open exchange in a common undertaking rather than a series of "canned" briefings restricted to technical "nonemotional'' issues and an "early and sustained interchange that includes the media and other message intermediaries."

Though involvement of the public is understood to enhance communication with those directly involved, relatively little understanding exists on how to best

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