U.N. scientists assessing the health impact of the wrecked Fukushima No. 1 nuclear plant on local residents said their estimates show the radiation doses are so low they do not expect to see any increase in cancer rates, based on data obtained so far, although they also urged follow-up studies.
The U.N. Scientific Committee on the Effects of Atomic Radiation also noted in a report Friday that the prompt evacuation of many residents from areas around the power station helped to reduce exposure from radioactive substances after three of its reactors suffered meltdowns in March 2011.
The committee estimated residents’ dose of radioactive iodine, which is associated with thyroid cancer, to be less than the critical 50-millisievert level, above which preventive iodine tablets are issued to young children. However, it also noted cases of children who had been exposed to as much as 66 millisieverts.
Doses of up to 15 millisieverts of cesium-134 and -137 were found in adult residents, much lower than the 100-millisievert threshold considered to increase the risk of solid tumors.
In the 1986 Chernobyl catastrophe, many children consumed milk tainted with a high concentration of iodine, resulting in an increase in thyroid cancer. But the U.N. committee said the quick evacuation of the local population following the Fukushima meltdowns reduced radiation doses by a factor of 10. The doses were also limited because the consumption of produce contaminated with radioactive substances was for the most part averted.
The results differ markedly from those in a report published by the World Health Organization in February that warned of a higher cancer risk for residents and nuclear plant workers around the Fukushima No. 1 complex than the average rate for Japan’s entire population.
Addressing this discrepancy, the committee said the WHO had to base the models and parameters for its estimates on data from only the first three months after the meltdowns. The committee, on the other hand, made use of precise dose distributions from an additional year’s worth of data, allowing it to present more up-to-date findings.
As for the workers at the No. 1 plant, the committee confirmed that two received thyroid doses of up to 12 millisieverts as a result of inhaling iodine at the beginning of the crisis. They are under medical surveillance and nothing out of the ordinary has been observed so far regarding their health, according to the report.
The committee said it only had limited information on the impact of the radioactive fallout on animals, plants and other species, calling for follow-up research, particularly in the Pacific.
The panel held a five-day meeting in Vienna through Friday to discuss the effect of the Fukushima disaster on local residents and others. Its report is expected to be presented to this autumn’s session of the U.N. General Assembly.