Physical dangers are widely appreciated but the mental effects are bigger.
With respect to the most recent Fukushima incident, Dr. Koichi Tanigawa, of Fukushima Medical University in Japan, says:
"Although the radiation dose to the public from Fukushima was relatively low, and no discernible physical health effects are expected, psychological and social problems, largely stemming from the differences in risk perceptions, have had a devastating impact on people's lives."
There are 437 nuclear power plants in operation around the world, but nuclear accident is uncommon. The most recent disaster was at the Fukushima Daiichi nuclear power plant in Japan in 2011.
There have been four other severe nuclear accidents (rated as level 5 or higher - "an accident with wider consequences") - Kyshtym in Russia in 1957, Windscale Piles in the UK also in that year, Three Mile Island in the US in 1979 and Chernobyl in Russia in 1986.
Mental distress of evacuation
In 2006, the UN (United Nations) Chernobyl Forum report concluded that the accident's most serious public health issue was the adverse effects on mental health.
Poor communication about the health risks associated with radiation levels made the problem worse.
Rates of depression and post-traumatic stress disorder (PTSD) remain elevated 20 years after the accident.
Fukushima saw similar problems. The Fukushima Health Management Survey reported that the proportion of adults with psychological distress was almost five times higher for evacuees. The proportion was 14.6%, compared with 3% in the general population.
Repeat evacuations and long-term displacement bring severe health care problems for the most vulnerable, the authors highlight. Mortality among older people in the first 3 months following evacuation went up by a factor of three.
In one of The Lancet papers, Prof. Akira Ohtsuru, of Fukushima Medical University, and colleagues discuss ways to protect the millions of residents who might be exposed to radiation after another nuclear accident.
Minimizing potential harms to physical and mental health could include responding to parental concerns about cancer risks for children and helping evacuees to adjust to new places, the paper says.
Fukushima offers lessons, the authors say. "One of the key tasks of the health services is to reliably communicate that in most nuclear accidents, very few people are exposed to a life-threatening dose of radiation," they report, adding:
"Physicians must play a key role in helping residents understand the health risks. Evacuation of a large population of vulnerable people in nursing homes and hospitals will also need careful planning and adequate medical support.
Additionally, screening for mental illness in residents relocated from their homes and providing mental health care will be essential."
70 years on from bombs
The long-term health impact of radiation exposure from the atomic bombings of Hiroshima and Nagasaki and from the Chernobyl nuclear accident are the subject of the report led by Prof. Kenji Kamiya, vice president of Hiroshima University in Japan.
A clear higher lifetime risk of cancer in survivors is shown by the Japanese Life Span Study, which followed 94,000 atomic bomb survivors from 5 years after the bombings in 1950 to the current day.
There was a dose-response for solid cancers and a higher risk for people exposed at younger ages.
After Chernobyl, an increased risk of childhood thyroid cancer among those with internal exposures from consuming radioactivity in food was also seen in affected areas. Hereditary effects in the children of survivors have not yet been detected.