1. From the Radiation Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, 9609 Medical Center Dr, Rockville, MD 20850 (M.O.B., N.J., D.V., M.M.D., M.S.L., C.M.K.); Institut de Radioprotection et de Sûreté Nucléaire, Fontenay-aux-Roses, France (M.O.B.); and Division of Environmental Health Sciences, School of Public Health, University of Minnesota, Minneapolis, Minn (B.H.A.).