TOKYO -- A total of 185 cases of thyroid cancer found in youngsters in the Japanese region hit by the 2011 nuclear disaster cannot be linked to radiation, which is not the biggest cause of health problems for residents, doctors said Thursday.
A team of doctors from Fukushima Medical University conducting a health survey of Fukushima residents found the 185 cases of malignant or suspected thyroid cancer in children. Ongoing thyroid checks using ultrasound are being done in phases on the 380,000 people who were 18 or younger and in Fukushima when the March 11, 2011, earthquake and tsunami triggered meltdowns at three reactors.
Experts say the number is many times higher than is typically found in Japan through touch and visual examination, although thyroid irregularities have been found at similar rates in children in three areas of the country.
The doctors said more thyroid cancer cases were found because of the blanket screening, not the radiation that leaked from the plant. They say evacuees' stress and changing lifestyles have prompted obesity and diabetes, increasing the risk of strokes and heart problems.
"Those thyroid cases have been found because we conducted the survey, not because of the radiation," said Akira Ohtsuru, an expert on radiation and thyroid ultrasound examination at the university. "The survey has caused over-diagnosis."
Ohtsuru said the blanket survey is likely to be finding many thyroid cases that would never be noticed otherwise. He said there is no way of telling pathologically if any cancer is radiation-induced.
Thyroid cancer is among the most curable cancers, though some patients who have their thyroid removed need lifelong medication and regular checks. Experts say many thyroid problems in Japan are linked to eating large amounts of seaweed and other food rich in iodine.
Still, children and their parents fear a stigma against such illnesses in Japan, where normalcy is highly expected. Some schoolchildren who moved outside of the prefecture were harassed for being evacuees from Fukushima, media reports say.
Thyroid irregularities have been found at a similar rate in three other prefectures in southern, central and northern Japan, said another doctor, university vice-president Koichi Tanigawa, adding that the radiation is not the biggest impact on the health of Fukushima residents. Their health has been hit harder by stress from evacuation and relocation, changing lifestyle and diet, as well as lack of exercise, he said.
A study by his team member, Tetsuya Ohira, has found obesity, diabetes, and liver and heart problems have increased among older evacuees compared to their health status before the tsunami, an increased risk of developing strokes, heart attacks and other cardiovascular problems.
The Fukushima disaster at one point forced more than 150,000 people to abandon their homes. The number has decreased significantly as more areas have been decontaminated and the government pushes to showcase the reconstruction. Subsidies for evacuees outside of Fukushima will be cut later this month.
International studies on Fukushima have predicted that cancer rates will not rise as a result of the nuclear accident, though some researchers say the rate of thyroid cancer in the prefecture is higher than what is generally found and could be related to radiation.
Ohtsuru acknowledged there are still unknowns about the impact of radiation on human health, citing the need for a long-term survey.
