1. Department of Radiation Biology and Biophysics and Environmental Health Sciences Center, University of Rochester, School of Medicine and Dentistry, Rochester. New York 14642
2. Kaiser-Permanente Medical Center. Santa Clara, California 95051
3. Department of Nutritional Sciences, University of California, Berkeley 94720
4. Kaiser Foundation Research Institute, Oakland, California 94511
5. Division of Biostatistics, University of Rochester, School of Medicine and Dentistry, Rochester. New York 14642