Daniel A. Vallero, PhD, is Adjunct Professor of Engineering Ethics in the Pratt School of Engineering at Duke University and former director of Duke's Program in Science, Technology, and Human Values. His professional experience spans three decades in the executive and legislative branches of the federal government and at universities, and he is recognized as a leader in environmental research, engineering education, ethics, and environmental justice. He is the author of three previous books on environmental engineering and risk assessment.

P. Aarne Vesilind, PhD, is Professor of Civil and Environmental Engineering in the Department of Civil and Environmental Engineering at Bucknell University. He serves on many technical and pro?fessional editorial boards and has written nine books on environmental engineering, solid waste management, education, and environmental ethics.