That's the conclusion of the most comprehensive investigation yet into the likely health effects of the world's worst nuclear accident since Chernobyl in 1986.

"The actions taken by the authorities to protect the public, such as evacuation and sheltering, significantly reduced the radiation exposures," says Wolfgang Weiss, chairman of the panel of 80 scientists that produced a report on the incident for the UN Scientific Committee on the Effects of Atomic Radiation.

So far none of the 25,000 workers at the site haS become ill with radiation-related conditions. But about 170 workers with exposures exceeding 100 millisieverts – the equivalent of receiving the maximum safe annual industry dose over five years all at once  – will be monitored to quickly detect any radiation-related effects on their thyroid, stomach, lungs and colon.