JEROME O. NRIAGU is Professor in the Department of Environmental and Industrial Health, School of Public Health, the University of Michigan, and an adjunct professor at the University of Waterloo. For many years he was a research scientist with the National Water Research Institute, Burlington, Ontario. He is the editor of the Wiley Series in Advances in Environmental Science and Technology and has edited, among many other volumes, Nickel and Human Health, Arsenic in the Environment, and Thallium in the Environment. Dr. Nriagu received BSc and DSc degrees from the University of Ibadan, Nigeria, an MS from the University of Wisconsin, Madison, and a PhD in geochemistry from the University of Toronto. He has published extensively in leading geochemical and environmental science journals and has received a number of awards for his work. He is a Fellow of the Royal Society of Canada. MILAGROS S. SIMMONS is a professor in the Department of Environmental and Industrial Health, School of Public Health, the University of Michigan, and an associate research chemist at the Center for Great Lakes Research at the University of Michigan. She is a coeditor of Food Contamination from Environmental Sources and Toxic Contaminants in the Great Lakes. She is a member of the American Chemical Society, Inter: American Chemical Society, Inter: American Photochemical Society, and the Society of Toxicology and Environmental Chemistry. Dr. Simmons received her BSc in chemistry from the University of Santo Tomas in Manila, the Philippines, and her MS and PhD in chemistry from Wayne State University. She has published extensively in the area of environmental photochemistry, the fate and effects of organic pollutants, and environmental analytical chemistry.