In major nuclear accidents, the greatest health risk to people is mental problems, including depression or post-traumatic stress disorder, rather than physical harm from radiation leakage, studies have found.
Those problems are often made worse by exaggerated estimations of the levels of radiation leakage, say scientists in a series of studies published in the journal The Lancet.
The studies mark the 70th anniversary of the atomic bombing of Hiroshima and Nagasaki by the United States, which ended World War II.
One of the nuclear accidents covered was the Fukushima incident in Japan, where damage to the nuclear power plant from the March 2011 earthquake and tsunami released significant amounts of radiation, leading to the evacuation of 170,000 people within a 20-mile radius of the plant.
While subsequent studies have found no evidence to expect any significant increase in cancer rates in the future as a result of radiation, psychological distress in evacuees has been five times the average, researchers say: 14.6 percent compared with just 3 percent 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," said Koichi Tanigawa of the Fukushima Medical University.
That's similar to findings on the impact of the 1986 nuclear accident at Chernobyl in Ukraine, researchers say.
A 2002 report by the United Nations said the greatest public health issue in the wake of that accident was its impact on people's mental health, made worse by inaccurate communication about possible health risk from the reported radiation levels.
There are undeniable long-term physical health effects on people directly exposed to high levels of radiation, experts acknowledge, citing Chernobyl where 134 workers involved in the emergency response and cleanup developed radiation sickness and 28 of them died.
However, the psychological damage to vast numbers of people living in regions affected by nuclear accidents is often overlooked, they say.
Simon Wessely, president of the Royal College of Psychiatrists in the United Kingdom, says The Lancet studies demonstrate that "the psychological and social consequences of nuclear accidents are more profound, long-lasting, divisive and difficult to manage than the more direct consequences of radiation leaks."
Rather than the extreme risk aversion that currently dominates thinking, more attention should be given to community engagement in terms of mental health concerns following any future accidents, he says.