1. Radiation Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, Maryland.
2. Laboratoire d'épidémiologie des rayonnements ionisants, Service de Radiobiologie et d'Epidémiologie, Institut de Radioprotection et de Sûreté Nucléaire, Fontenay-aux-Roses, France.
3. Division of Environmental Health Sciences, School of Public Health, University of Minnesota, Minneapolis, Minnesota.