People caught up in nuclear disasters are far more likely to suffer severe psychological disorders than any harm from radiation, scientists say.
Five nuclear accidents rated as 'severe' have occurred during the past 60 years - Russia's Kyshtym in 1957, Windscale in Britain in 1957, Three Mile Island in the United States in 1979, Chernobyl in 1986 and Japan's Fukushima in 2011.
But despite a widespread misconception that nuclear disasters have caused considerable death and physical illness, researchers have found that the mental health effects caused by factors such as having to evacuate homes or simply fear of radiation have been far more profound.
"In most nuclear accidents very few people are exposed to a life-threatening dose of radiation," wrote Akira Ohtsuru of the Fukushima Medical University (FMU).
The psychological burden for people living in regions affected by nuclear disasters is often overlooked, added Koichi Tanigawa of FMU, who led one of a series of studies published in The Lancet to mark the 70th anniversary of the US atomic bombing of Hiroshima and Nagasaki.
After the Fukushima disaster, some 170,000 residents were evacuated from a 30km radius of the plant. The proportion of adults with psychological distress was found to be almost five times higher among disaster evacuees - at 14.6 per cent compared with just 3 per cent in the general population.
"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," Tanigawa said.
The United Nations Chernobyl Forum report published in 2006 found that even 20 years after the accident, rates of depression and post-traumatic stress disorder remained higher than normal. Poor communication about the health risks of reported radiation levels was blamed for exacerbating the effect.
Radiological health experts believe that analysing such events gives vital information on how best to protect those living near nuclear power plants. At least a third of the world's 437 nuclear power plants have even more people living within 30km than Fukushima, while 21 have more than a million people nearby and six have more than 3 million.