No known health effects have been identified in Japanese workers who were exposed to radiation following last year's Fukushima Daiichi nuclear power plant crisis, the United Nations (UN) reported on Wednesday.
According to preliminary studies and assessments, the UN Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) stated that although six workers have died since the accident, none of the deaths were linked to irradiation and no clinically observable effects have been reported.
In what was reported to be the worst nuclear accident since the 1986 Chernobyl disaster, the building housing the Fukushima Daiichi nuclear power plant exploded and three of its nuclear reactors suffered a meltdown in March 2011, when a massive earthquake and tsunami struck the Japanese coastline.
Two months after the accident, UNSCEAR agreed to carry out a scientific assessment of the level of radiation exposure and health risks resulting from the accident. A 19-kilometer (11.8 mile) exclusion zone still surrounds the disaster site over a year after the disaster.
As of January 31, a total of 20,115 workers have been involved in operations at or near the plant following the accident, according to the report, which UNSCEAR Chair Wolfgang Weiss said was based on a wide variety of sources. Several workers were irradiated after contamination of their skin.
"There is very detailed information so as to assess the public doses but it will be more challenging to validate the workers' exposure," Weiss said, adding that work is still in progress. He said their assessment is being conducted with "careful scrutiny to ensure its quality, and we have a long way to go yet."
According to UNSCEAR, its Committee members now have a good understanding of the nature and composition of the releases into the atmosphere from damaged reactors, and together with measurements of radioactive elements in the air, soil, water and food, the study will be able to assess doses to adults and children in different areas of Japan, considering important organs such as the thyroid.
"We have been given information about measurements made on the thyroids of over 1,000 children in Iitate village, Kawamata town and Iwaki city," said Weiss. "Also, a survey in Fukushima prefecture is aiming to evaluate irradiation levels for some two million people living in the prefecture at the time of the accident. The results of the UNSCEAR assessment for these areas will be compared with the Japanese measurements and analysis, and any differences will be highlighted and addressed."
UNSCEAR, which is holding its annual meeting in Vienna this week, is scheduled to present its final report on the levels and effects of radiation exposure from the accident towards the end of 2013.