Massive amounts of radiation have been released from the Fukushima Daiichi Nuclear Power Plant since it was hit by the tsunami caused by last year's Great East Japan Earthquake. Now, more than a year later, the cleanup work is progressing, but many radiation hotspots remain, and there is continuing anxiety about how radiation might affect the health of residents living near the plant. Japan is a world leader in epidemiology -what can its studies tell us about the health effects of long-term exposure to relatively low doses of radiation? Children are said to be especially vulnerable -are the effects different for them? There are still many questions that remain to be answered. We report on the latest Japanese studies into the impact of radiation on the human body.