A health ministry team is studying whether around 2,000 workers who helped contain the nuclear disaster at the Fukushima No. 1 power plant that started in March 2011 are at risk of thyroid cancer, one of the team members said Sunday.
The research team of the Health, Labor and Welfare Ministry aims to determine how radiation exposure as a result of the nuclear crisis has affected the plant workers, who were exposed to greater levels of radiation than local residents, who in large part evacuated.
Tomotaka Sobue, an Osaka University professor who is part of the ministry team, announced the study during an international research gathering in Tokyo on radiation and thyroid cancer.
Sobue said the team will check whether 1,972 workers are suffering from cancer or have lumps. The workers engaged in work at the Fukushima No. 1 plant shortly after the disaster started and their thyroid glands were exposed to radiation doses exceeding 100 millisieverts.
The team will also examine another roughly 2,000 workers of Tokyo Electric Power Co. who were exposed to lower doses and compare the results of the high- and low-risk groups.
Radioactive iodine released in nuclear disasters tends to accumulate in thyroid glands, particularly in young people.
Fukushima Prefecture has examined the thyroid glands of people under age 18 and has so far found 33 with thyroid cancer.
But experts at the three-day international research gathering through Sunday concluded it is unlikely the cancer was due to radiation exposure caused by the Fukushima No. 1 meltdowns.
The experts said it is highly likely that some Fukushima residents discovered they had thyroid cancer because sophisticated equipment was used for health checks. None of the sufferers was a baby and the discovery of thyroid cancer was within three years of the 2011 nuclear disaster.
Citing the 1986 Chernobyl nuclear catastrophe, the experts said there was an increase in thyroid cancer in children in the following four to five years, and that babies or young children living in the affected areas then were at high risk of developing the cancer.