This workshop explored the complex issues involved in scientific measurement of environmental risk. Specific purposes were to articulate policy issues that concern the use of scientific data in environmental risk assessment and to contribute to the dialogue from which better policy might emerge. Viewpoints of workshop participants from the executive and legislative branches of government, industry, the academic community, and the policy analysis community are provided under these titles: "Differences in Assessing Risks for Food and Drugs" (J. Richard Crout); "Risk Assessment and the Legislative Process" (Thomas H. Moss); "Science and Environmental Risk: Policy Issues" (Denis Prager); "Regulating Toxic Substances: An Update" (Morton Corn); "New Scientific Issues" (Robert J. Moolenaar); "The Clean Air Act: An Update" (Gilbert S. Omenn); "Etiological Factors in Human Cancer" (John Higginson); "Future Directions for Science and Policy" (William W. Lowrance); "Risk Analysis at the Office of Technology Assessment" (John H. Gibbons); and "Industrial Perspective on Regulating Carcinogens" (Monte C. Throdahl). Among the broad areas of concensus reported are those indicating that federal regulations are needed (especially in regulating chemical substances that affect human health) and that there is rarely an effective dialogue between industry and government before issues become critical and debate assumes a confrontational character. (JN)