The news media and environmental groups are frequently blamed for public overreaction to unfortunate events like major oil spills; an example of the social amplification of risk. A disconnect between public views regarding spill consequences and necessary remedies on the one hand, and expert opinion on these same questions on the other, is a frequently identified consequence of this social amplification. A more comprehensive examination of the ways in which scientific messages can fail to inform the public or to rationalize public policy suggests however that a more complex phenomenology is at work. Perceived risks can be attenuated as well as amplified, and many organizations besides the news media contribute to the shaping of public risk attitudes. As a result, social and political questions of blame can prove difficult to disentangle from scientific questions of impact. Both social amplification and social attenuation of messages about the risks of oil production and transport are evident in public responses to the Exxon Valdez spill, and both continue to affect the debate about oil production and its transport by sea today. Oil-spill science has had mixed success in modulating these risk concerns, as the conduct of oil-spill science has itself felt the effects of risk amplification and attenuation. Because these difficulties are bound up in questions of social trust, institution building is seen as the best long-term strategy for redress. The Prince William Sound Regional Citizen's Advisory Council offers a hopeful example that such institution building can occur, given sufficient motivation, resources and the means and time for diverse interests to develop a shared vision of the risks to be addressed. (C) 2002 Elsevier Science Ltd. All rights reserved.