The 104 are among 300,000 young people who were aged 18 or under at the time of the 2011 Fukushima nuclear disaster and whose results of thyroid gland tests have been made available as of June 30. They were eligible for the tests administered by the prefectural government.
Of these 104, including 68 women, the number of definitive cases is 57, and one has been diagnosed with a benign tumor. The size of the tumors varies from 5 to 41 millimeters and averages 14 mm.
The average age of those diagnosed was 14.8 when the Great East Japan Earthquake and tsunami triggered the meltdowns at the Fukushima No. 1 nuclear power plant in March 2011.
However, government officials in Fukushima say they do not believe the cases of thyroid gland cancer diagnosed or suspected in the 104 young people are linked to the 2011 nuclear accident.
The figure can be extrapolated for comparison purposes to an average of more than 30 people per population of 100,000 having definitive or suspected thyroid gland cancer.
The figure is much higher than, for example, the development rate of thyroid cancer of 1.7 people per 100,000 among late teens based on the cancer patients’ registration in Miyagi Prefecture.
But experts say the figures cannot be compared because the test in Fukushima Prefecture covers a large number of people who have no symptoms.
Experts are divided over whether the cases of thyroid gland cancer diagnosed or suspected in the 104 young people should be linked to the 2011 nuclear accident.
In connection with the 1986 Chernobyl disaster, the number of young people diagnosed with thyroid cancer rose only after four years. The cancer is also known to develop slowly.
But some researchers say that the occurrence of thyroid gland cancer is likely to be increased by the Fukushima nuclear accident.
“Many people are being diagnosed with cancer at this time, thanks to the high-precision tests,” said Yoshio Hosoi, professor of radiation biology at Tohoku University. “We must continue closely examining the people’s health in order to determine the impact of radiation exposure on causing thyroid tumors.”
By regions, 27.7 people per 100,000 people have been diagnosed with definitive or suspected thyroid cancer in the Aizu region, located 80 kilometers or farther from the crippled nuclear plant. The number could increase after thorough examinations are completed for people in the region
Around 35 people per 100,000 have been diagnosed with definitive or suspected cancer in the Nakadori region, which includes Fukushima city and several municipalities designated as mandatory evacuation zones, and the coastal Hamadori region.
Hokuto Hoshi, who chairs a panel that discusses matters related to the prefectural survey on the health impact from radiation on Fukushima’s residents, said the panel’s subcommittee will soon analyze the test results to determine the impact of the accident on the thyroid tumor rate.
“In order to scientifically compare the results of the development rates of each region, we must take into account age and other characteristics (of the 104 people),” he said.
The prefecture also plans to continue medical checkups on residents in the prefecture and use the test results as a basis for comparison in the future, prefectural officials said.
Source: The Asahi Shimbun http://ajw.asahi.com/article/0311disaster/fukushima/AJ201408240011