• Leukaemia
• risk assessment
• radiation

The assessment of detrimental health risks for humans, due to exposures from ionising radiation sources such as γ-rays, x-rays and neutrons, which penetrate deeply into the human body, has been an endeavour which has increased in magnitude and effort over the last century. Solid cancer and leukaemia incidence and mortality have emerged as having radiation as an important proven risk factor from the many indicators of cellular damage and health effects that have been investigated to date. Studies on survivors of the World War II atomic bombings over Hiroshima and Nagasaki, who were exposed mainly to γ-rays and neutrons, continue to provide valuable radiation epidemiological data and quantitative assessments of the radiation related solid cancer and leukaemia risks.1 The cohort of the atomic bomb survivors is unique and characterised by: the large number of cohort members (approximately 105 000); the long follow-up period of more than 50 years; a composition that includes males and females, children and adults; whole-body exposures (which are more typical for radiation protection situations than the partial-body exposures associated with many medically exposed cohorts); a large dose range from natural to lethal levels; and an internal control group with negligible doses, that is, those who survived at large distances (>3 km) from the hypocentres. Results from this cohort have formed a basis in the construction of …