In March 2021, the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) released a report on the effects of radiation after the Fukushima Daiichi Nuclear Power Plant accident. (Reference link 1)
This report described the thyroid cancer examinations (ultrasonography of all residents under the age of 18 at the time of the nuclear accident) , which have been administered as part of the “Fukushima Health Management Survey” by the prefecture, as “screening” (Thyroid cancer screening).
In October 2018, the International Agency for Research on Cancer (IARC) issued a recommendation not to conduct mass screening for thyroid cancer which is a great concern after a nuclear accident.
IARC is the specialized cancer research agency of the World Health Organization (WHO). Instead, it advised administering a “monitoring program” for individuals from fetuses to adolescents exposed to radiation of 100-500 mSv or higher after the accident. (Reference link 2)
However, in the March report, UNSCEAR saw no substantial changes in the administration of the thyroid exams in Fukushima and thus determined that the current survey is still a “screening,” rather than a monitoring program.
So what is lacking in Fukushima’s thyroid examination to satisfy the conditions that the monitoring program recommended by IARC requires?
Three points below, at least, are the differences between Fukushima’s thyroid examination and IARC’s recommended monitoring program.
1．How do they decide to take a test: Is it after discussing with family and consulting with a doctor?
The monitoring program is a mechanism that provides individual consultation to those who are concerned about their health effects of the internal radiation dose or the possibility of thyroid cancer. It also helps people to decide whether or not to undergo a thyroid test.
The monitoring program can be likened to genetic counseling. Genetic counseling provides you with information about how genetic conditions, such as chromosomes and genes, might affect you or your family. The choice is fully voluntary: those who are concerned individually contact medical institutions for consultation. Examples of questions asked at genetic counseling are “Is my own or my family’s illness heritable to my child?” “One of my relatives was diagnosed with cancer that is likely to be inherited, so I also want to take a genetic test,” “Many relatives have cancer. I have the same cancer myself. I want to know if it is hereditary cancer,” and so on. (Reference link 3)
The IARC recommends a non-mandatory monitoring program like genetic counseling for testing for thyroid cancer after a nuclear disaster.
Cancer testing can have a lasting, significant impact on the lives of the person and their family, depending on the outcome. Therefore, the IARC states that the monitoring program “should include the individual, his/her family, and clinician, in a decision-making process,” to decide from whether or not to have a test to, if so, how to do it.
Then what about Fukushima’s thyroid examination?
First, it’s performed in school for children up to high school during school hours (hereinafter school examination). Only a brief explanation is given, providing some papers and a few minutes of video footage. Not enough information is given, neither before nor after the tests, regarding the benefits and risks of the test.
For these points, it’s apparent that school examinations cannot be called a “monitoring program.” In addition, the ratio of those who take the tests is close to 90%, which shows the test is regarded rather mandatory than voluntary.
Those who are subject to a thyroid examination and have graduated from high school will go to general venues for examination. At those venues, a brief lecture is given prior to the test on the benefits and risks of the thyroid test, dividing people into small groups of 5 to 10.
However, those who came to the venue and take the lecture are people who have already decided to take the tests and submitted consent forms. Therefore, even after high school, information necessary for decision-making is not provided to examinees when it is needed by discussing with their families and doctors. Moreover, a one-sided lecture to a group of 5 to 10 people is far from individual consultation.
For these reasons, Fukushima’s thyroid examination does not meet the requirements advocated by IARC and is therefore not a monitoring program.
2．How target people are recruited?
A monitoring program should not actively recruit target people (passive recruitment). If people are prompted in any form to take the examination, that is active recruitment.
For Fukushima thyroid examinations, subjects will receive a notice of the examination and a form of consent by mail from Fukushima Medical University. However, if you are a student and late in sending back the consent, you will be urged by the school to submit it promptly. Therefore, at the school level, active recruiting is still continuing.
In this respect too, Fukushima’s thyroid examination differs from a monitoring program.
3．Is the person making informed decisions?
The IARC states that a monitoring program should be conducted in the best
possible way according to the person’s values, wishes, and circumstances, under the principle of “people-centered health services”.
In January 2021, a result of a fact-finding survey conducted by Fukushima prefecture was reported at the Fukushima Prefectural Health Survey Review Committee. According to the report, at two of the three high schools, students who didn’t consent to the examination remained in classrooms.
(Reference link 4)
In interviews with the subjects of the test who were then in high school, those who took the tests lined up and walked to the gym and they didn’t even understand the content of the test. Similarly, results of a survey conducted by Fukushima Medical University in 2018 indicated that 80% of the families of the examinees didn’t know the downsides of the thyroid examination (reference link 5).
Hence, it is also hard to say that test takers have made a fully informed decision.
The above three points can be cited as the differences, at least, between the Fukushima thyroid examination and the monitoring program recommended by IARC.
IARC shows a reference dose rate of 100 to 500 mSv for which a monitoring program should be considered. The estimated first-year exposure dose after the Fukushima Daiichi nuclear accident was 2.2 to 30 mSv on average for a one-year baby according to the UNSCEAR 2020 report and it is
significantly below the rate proposed by IARC.
Reference link (Japanese other than UNSCEAR report)
(1) UNSCEAR 2020 Report (English)
(2) Recommendations for thyroid monitoring after a nuclear disaster
International Cancer Research Institute (IARC)
(3) Japan Genetic Counselor Association
(4) Results of the current survey of thyroid examinations at schools: report at the 40th Fukushima Prefecture “Prefectural Health Survey” Review Committee https://www.pref.fukushima.lg.jp/uploaded/attachment/422936.pdf
(5) Fukushima Report “Awareness of the risks and benefits of Fukushima thyroid examinations”