The subject of this volume--uncertainties in risk assessment and management--reflects an important theme in health, safety, and environ mental decision making. MOst technological hazards are characterized by substantial uncertainty. Recent examples include nuclear waste disposal, acid rain, asbestos in schools, carcinogens in food, and hazardous waste. realing with such uncertainty is arguably the most difficult and challeng ing task facing risk assessors and managers today. Four primary sources of uncertainty in risk assessment and management can be identified: (1) uncertainties about...