Learning from Chernobyl in Fukushima5th International Expert Symposium in Fukushima on Radiation and Health focuses on causes of thyroid cancer
The fifth installment of the International Expert Symposium in Fukushima on Radiation and Health, which was launched in the wake of the accident at the Fukushima Daiichi Nuclear Power Station triggered by the earthquake that struck northeastern Japan in March 2011, was held in Fukushima City on September 26-27. The theme of this symposium was thyroid cancer in children, and how the lessons from the Chernobyl accident 30 years ago can be applied to Fukushima today. The symposium dealt with the question of whether or not there has been “overdiagnosis and overtreatment,” and the expert symposium discussed the best way to proceed with screening going forward. The symposium’s recommendations are to be compiled and published at a later date.
International specialists draw lessons from Chernobyl
The symposium was organized by The Nippon Foundation and the Sasakawa Memorial Health Foundation, which conducted health screening of children in the area around Chernobyl over 10 years from the time of the accident, together with Fukushima Medical University and Nagasaki University. Sessions featured 24 specialists from Japan and overseas, affiliated with international organizations including the World Health Organization (WHO), the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR), and the International Atomic Energy Agency (IAEA). In his opening remarks, Yohei Sasakawa, Chairman of The Nippon Foundation, expressed his hope that the results of the research conducted by these highly experienced specialists and their recommendations would lead to policy proposals going forward.
The symposium was divided into four sessions: (1) Lessons from Chernobyl: an Examination of Radiation Risks, Based on International Consensus and Evidence Related to Thyroid Cancer, 30 Years after the Nuclear Accident; (2a) Thyroid Cancer: The Reality of Chernobyl; (2b) Thyroid Cancer: Questions for Fukushima; and (3) From Chernobyl to Fukushima. The researchers gave keynote addresses and presented research reports to almost 200 medical professionals and researchers in attendance.
Screening children in Fukushima
After the accident in Fukushima, the prefectural government conducted two rounds of screening for residents aged roughly 18 and younger, with the first round covering 300,000 children and the second round covering 260,000. Of those children, 116 were diagnosed as having a malignant or possibly malignant tumor in the first round and 57 were diagnosed in the second round, and 134 underwent surgery to have their thyroid gland removed. Of these 134 children, 133 had papillary thyroid carcinoma, which rarely leads to death even if left untreated, and the one other child’s nodule was benign. Reactions to this data have ranged from “this was the result of outdoor exposure from the nuclear accident,” to “these were false positives that would not normally be diagnosed as cancer,” the result of the highly precise ultrasound screening of a large sample of subjects. This division of opinion has resulted in an unclear picture of the actual situation. At the symposium, researchers from Russia, Ukraine, and Belarus pointed out the differences with Chernobyl, namely that the amount of radiation emitted at Chernobyl was much greater than at Fukushima, and that in Chernobyl children continued to drink milk from cows that were eating contaminated feed. In addition, Chernobyl did not see an increase in thyroid cancer until four to five years after the accident, and in any case, the amount of radiation emitted at the Fukushima accident was so small that it would have almost no impact on people’s health.
Danger of overdiagnosis
Researchers from Fukushima Medical University who were involved in the screening added that highly precise, ultrasonic screening could create new uncertainties through overdiagnosis and that it is important to prevent overdiagnosis and overtreatment. A researcher from South Korea added that screening in areas near four nuclear power plants there showed an increase in diagnoses of thyroid cancer but with no change in the mortality rate, indicating that the increase in cases was the result of increased screening. Other conclusions drawn were that radiation exposure from the Fukushima accident was unlikely to cause an increase in the number of cancer cases in the future, but that it would be necessary to continue to monitor the situation going forward. The symposium’s findings will be summarized and a set of recommendations for future screening will be compiled, and these are scheduled to be released later this year.
Communications Department The Nippon Foundation