1. From the Radiation Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, 9609 Medical Center Dr, Rockville, MD 20850 (D.V., C.M.K.); Weddington, NC (R.C.Y.); Landauer, Glenwood, Ill (C.P.); and Institut de Radioprotection et de Sûreté Nucléaire, Fontenay-aux-Roses, France (M.O.B.).