1. Space Radiation Analysis Group, NASA Johnson Space Center, Houston, TX, USA
2. Cancer Epidemiology Unit, Nuffield Department of Population Health, University of Oxford, Headington, Oxford, UK
3. Radiation Epidemiology Branch, National Cancer Institute, Bethesda, MD, USA
4. Department of Radiation Sciences, Institute of Radiation Medicine, Helmholtz Zentrum München, Neuherberg, Germany
5. Centre for Occupational and Environmental Health, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK
6. Department of Statistics, Radiation Effects Research Foundation, Hiroshima, Japan