Fifty-nine young people in Fukushima prefecture have been diagnosed with or are suspected of having thyroid cancer, but experts are divided about whether their illness is caused by nuclear radiation.
All of them were younger than 18 at the time of the nuclear meltdown in the area in March 2011. They were identified in tests by the prefectural government, which covered 239,000 people by the end of September.
At a meeting hosted by Japan's Environmental Ministry and the prefectural government on Saturday, most experts were not convinced radiation leaks from the Fukushima nuclear plant could trigger thyroid cancer in children so soon, the Asahi Shimbun reported yesterday.
Among those who voiced alarm was Toshihide Tsuda, a professor of epidemiology at Okayama University. He called upon the government to prepare for a possible increase in cases in the future.
"The rate at which children in Fukushima prefecture have developed thyroid cancer can be called frequent, because it is several times to several tens of times higher," the newspaper quoted him as saying.
He compared the figures in Fukushima with cancer registration statistics throughout Japan from 1975 to 2008 that showed an annual average of five to 11 people in their late teens to early 20s developing cancer for every 1 million people.
Tetsuya Ohira, a professor of epidemiology at Fukushima Medical University, disagreed. It was not scientific to compare the Fukushima tests with cancer registry statistics, he argued.
In November, prefectural officials deemed it unlikely that the increase in suspected and confirmed cases of cancer was linked to radiation exposure.
In the Chernobyl disaster of 1986, it was not until four or five years after the accident that thyroid cancer cases surged.
"It is known that radioactive iodine is linked to thyroid cancer. Through the intake of food, people may absorb and accumulate it inside glands," said Dr Choi Kin, a former president of the Hong Kong Medical Association.
Children might absorb more of it than adults because they were still growing, he said, but it remained to be proven that the radioactive iodine came from the nuclear disaster instead of the normal environment.
The 2011 earthquake and tsunami crippled the Fukushima plant, causing the meltdown of three of its six reactors. More than 23,000 people were killed.