“RADIATION exposure following the nuclear accident at Fukushima-Daiichi did not cause any immediate health effects. It is unlikely to be able to attribute any health effects in the future among the general public and the vast majority of workers.” This is the conclusion of the Vienna-based United Nations Scientific Committee on the Effect of Atomic Radiation (UNSCEAR). More than 80 leading international scientists worked on analysing the information available on the levels and effects of exposure after the disaster in March 2011. When the committee’s report is published, it will be the most comprehensive international scientific analysis of the information available to date.
“The experience from the 1986 Chernobyl accident has shown us that apart from any direct impact on physical health, the social and societal effects, and their associated health consequences in the affected population will need special attention in the coming years,” said Carl-Magnus Larsson, Chair, UNSCEAR.
On the whole, the exposure of the Japanese population was low, or very low, leading to correspondingly low risks of health effects later in life, said a UNSCEAR release. The actions taken to protect the public (evacuation and sheltering) significantly reduced the radiation exposure that would have otherwise been received, concluded the committee.
The doses delivered for the two most significant radionuclides were quite different: doses to the thyroid, mainly from iodine-131, ranged up to several tens of milligray and were received within a few weeks after the accident; the whole-body (or effective) doses, mainly from caesium-134 and caesium-137, ranged up to 10 or so millisieverts (mSv) and will be received over the lifetime of those exposed. The additional exposure received by most Japanese people in the first year and subsequent years are less than the doses received from natural background radiation (which is about 2.1 mSv a year). This is particularly the case for Japanese people living far from Fukushima, where annual doses of around 0.2 mSv from the accident are estimated, arising primarily through ingestion of radionuclides in food. According to the study, no radiation-related deaths or acute effects have been observed among nearly 25,000 workers (including Tokyo Electric Power Company (TEPCO) employees and contractors) involved at the accident site. Given the small number of highly exposed workers, it is unlikely that excess cases of thyroid cancer owing to radiation exposure would be detectable.