The most lasting health impact of the Fukushima nuclear disaster will likely be psychological not physical, according to a trio of studies published Friday in The Lancet.

Moreover, the mental health toll comes not only from the trauma of dislocation and the spectre of harmful radiation, but from deficiencies in the way civic and health officials managed the crisis, the articles argued.

The meltdown at the Fukushima Daiichi facility in March 2011, provoked by a massive earthquake and tsunami, is one of only five nuclear power plant accidents to be rated five or higher since the advent of atomic energy.

It resulted in the evacuation of 170,000 people within a 30-kilometre (19-mile) radius of the plant, and caused massive disruption of family life and local economies.

In 2014, half of more than 20,000 evacuated households who responded to a government survey were still separated from family more than three years after catastrophe struck.

But physical health impacts have been limited.

In contrast to the 1986 explosion in Chernobyl that provoked an increase in thyroid cancer among children in affected areas and perhaps other cancers yet to be detected, the Fukushima debacle is unlikely to cause hikes in cancer rates due to radiation exposure, according the a 2013 UN scientific report.

However, even if "no discernible physical health effects are expected, psychological and social problems, largely stemming from differences in risk perception, have had a devastating impact on people's live," commented Fukushima Medical University's Koichi Tanigawa, who led 15 experts in assessing health impacts from major nuclear accidents worldwide.

Repeated evacuations and long-term displacement, fractured families, disrupted services and the lingering uncertainty about the health consequences of invisible radiation caused widespread anxiety.

The percentage of adults experiencing psychological stress remains five times higher among evacuees than the general population, and deaths among the elderly - an especially vulnerable population - increased threefold in the three months after the accident.

In the same 2014 survey, 68 percent of respondents reported mental or physical health problems in their families, 57 percent disturbed sleep, and 47 percent depression moods.

- Fear of stigma -

The studies also fault shortcomings in emergency management that added additional sources of stress.

Mixed messages about the severity of the accident and "restriction of information ... might further increase public anxiety, leading to distribution of inaccurate information and public distrust," one of the studies concluded.

Health officials, the researchers said, failed to anticipate how certain situations might create additional psychological pressure. And a poor understanding of how people perceive the threat of radiation led to errors in communication.

Screening for radiation exposure, for example, to the thyroid gland - susceptible to radiation cancer - in many cases added stress rather than relieving it.

Many young women in affected areas feared being stigmatised because of presumed impacts on future pregnancies and genetic inheritance.

"The major effect on health of the general population from both Chernobyl and Fukushima is not related to the actual effects of radiation, but the fear of radiation," noted Geraldine Thomas, a professor of molecular pathology at Imperial College London, after reading the reports.

"An over-reaction can produce risks in its own right that may be greater than the health risks posed by the accident itself," she wrote in a comment.

Twenty-one of the world's nearly 440 nuclear power plants have more than one million people living within a 30 kilometre radius, and six have more than three million.