The percentage of children with thyroid gland cysts is about the same in Tokyo and Fukushima, indicating that radiation from the nuclear accident has not affected the rate in the disaster-hit prefecture, doctors said.
The percentage of children with thyroid gland cysts is about the same in Tokyo and Fukushima, indicating that radiation from the nuclear accident has not affected the rate in the disaster-hit prefecture, doctors said.
Kenji Iwaku and other physicians at Ito Hospital in Tokyo reported their findings at an annual meeting of the Japan Thyroid Association on Nov. 30. They compiled records of 2,753 children, age 15 and under, who underwent ultrasound thyroid gland tests at the hospital between 2003 and August this year.
They said cysts were found in 36 percent of the Tokyo children.
The cysts either shrank or disappeared in 42 percent of the 189 children who underwent more than one test. They grew larger in 14 percent of them and remained unchanged in 44 percent.
None of the Tokyo children developed cancer or other malignant diseases while they were under follow-up monitoring. Most cysts in the human body are benign tumors, and many disappear over time or are surgically removed.
The occurrence rate in Tokyo was similar to those for residents 18 or younger in Fukushima Prefecture. They have been undergoing thyroid gland tests by the prefectural government since the accident started to unfold at the Fukushima No. 1 nuclear plant in March last year.
Cysts were found in 35 percent of Fukushima children tested in fiscal 2011 and in 42 percent of those tested so far in fiscal 2012.
Until the results of the Tokyo study, a lack of comparable data from other regions made it difficult to tell if the Fukushima figures represented an increase in the rate of cysts among children.
"The authors of the latest study used testing equipment of the same grade that is used in Fukushima, and their samples include data taken before the nuclear disaster," said Shigenobu Nagataki, professor emeritus of thyroid studies at Nagasaki University. "There is likely no impact of radiation on the occurrence rate of cysts in the Fukushima children."
Thyroid cancer is known to have increased among local children following the Chernobyl nuclear disaster in 1986.
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