A survey shows that a small amount of radioactive iodine has been detected in the thyroid glands of hundreds of children in Fukushima Prefecture.
The result was reported to a meeting of the Japan Pediatric Society in Tokyo on Saturday.
A group of researchers led by Hiroshima University professor Satoshi Tashiro tested 1,149 children in the prefecture for radiation in their thyroid glands in March following the accident at the Fukushima Daiichi nuclear plant. Radioactive iodine was detected in about half of the children.
Tashiro says radiation in thyroid glands exceeding 100 millisieverts poses a threat to humans, but that the highest level in the survey was 35 millisieverts.
Tashiro says based on the result, it is unlikely that thyroid cancer will increase in the future, but that health checks must continue to prepare for any eventuality.