My presentation for the Geneva Learning Foundation at the 15th meeting of the WHO Radiation Emergency Medical Preparedness and Assistance Network (REMPAN), World Health Organization, Geneva – 3-5 July 2017. Featured image: Participants of the Radiation Effects Research Foundation’s (RERF) Seventh Epidemiological Training Workshop for Biologists. The objective of the RERF is to conduct research and studies for peaceful purposes on medical effects of radiation and associated diseases in humans, with a view to contributing to maintenance of the health and welfare of the atomic bomb (A-bomb) survivors and to enhancement of the health of all humankind.