Thyroid Exposure In Fukushima Children

An updated survey of children in Fukushima prefecture who were exposed to fallout from the Fukushima Daiichi nuclear disaster has been released. Of 38,114 children under age 18 that were tested, 13,646 of them had some form of detectible nodule or cyst on their thyroid. With 35.3% of them being either a nodule smaller than 5mm or a cyst smaller than 20mm. .5% of the children found with detectable anomalies had a nodule larger than 5mm or a cyst larger than 20mm. Fukushima Voice translated the report, we thank them for their hard work in doing so.

With the growing evidence of thyroid issues in children exposed in Fukushima it also raises even more questions. Is this a case of finding more because people are actively looking? Are they truly related to the children’s exposure? If they are related what does that mean for their health and what can be done to assure they receive proper proactive health care? The technology for scanning and baseline populations recorded in Japan from before the Fukushima disaster raise alarming concerns why these exposed children have such a high nodule level so soon after the disaster. What do thyroid nodules mean? What should be done to assure the safety of these children exposed to a nuclear power accident?


Thyroid cysts and nodules in children:

  • The thyroid gland can be affected by exposure to radiation. The thyroid glands of children are especially sensitive to radiation, much more so than the thyroid gland of an adult.
  •  Radiation exposure appears to cause a number of different thyroid problems, including an underactive thyroid (hypothyroidism), thyroid nodules, and thyroid cancer.
  • The younger the child is when the radiation exposure occurs, the greater is the risk of these problems occurring.
  • The three major ways a thyroid is impacted after radiation exposure, hypothyroidism, thyroid nodules, thyroid cancer

Hypothyroidism can appear months or years after radiation exposure, it is most likely to occur 2-3 years after exposure. Hypothyroidism can be treated with medication to replace the missing thyroid hormones. Symptoms can include: fatigue, sluggishness, increased sensitivity to cold, constipation. pale, dry skin, a puffy face, hoarse voice, an elevated blood cholesterol level, unexplained weight gain, muscle aches, tenderness and stiffness, pain, stiffness or swelling in your joints. muscle weakness, brittle fingernails and hair, depression, poor mental development, poor growth, resulting in short stature, delayed development of permanent teeth and delayed puberty. Hypothyroidism in infants can lead to severe physical and mental retardation if not treated even in mild cases.

Thyroid nodules usually appear several years, typically 8-12 years after exposure. About half of the thyroid nodules in children less than 15 years of age are malignant. They can be detected early by ultrasound and by physical examination when they become larger. Both fluid filled cysts and hard nodules are considered nodules by the medical community.  A malignant result is obtained in about 5% of biopsies, with only 50-75% of those actually being cancer. There are certain blood tests that can help determine if a nodule is malignant that can be used to assist the biopsy and a DNA test is in the works. Any nodule or cyst determined to be cancerous or suspicious of such should be surgically removed. Nodules that are not large or fast growing generally should be watched. Fast growing nodules can be an indicator of an aggressive form of thyroid cancer.


Early results in Fukushima & Government response:

The director of the government run study that found the nodules in a group of Fukushima children has dismissed them all as “mostly normal”.  Shunichi Yamashita, is still in charge of this government project. He is well known in Japan and elsewhere as “Dr. 100 mSv” after claiming that was a safe level of human exposure and telling residents to “smile” to prevent radiation induced illness. His previous research work in 2001 documented that normal children in Nagasaki had 0% nodules and 0.8% cysts. This is in stark contrast to the over 35% being found in Fukushima children. The high incidence so soon after exposure in Fukushima has defies a solid answer. Research in Gomel, Belarus had a rate of thyroid nodules in children, 5 to 10 years after the Chernobyl accident at 1.74%. So either there was considerably more exposure than has been documented in Fukushima, the results had an extremely high incidence of finding nodules that would exist in a normal population or something else is factoring into the issue. The high incidence of nodules in the study at Fukushima currently defies an easy explanation.

According to the 2001 study Yamashita co-authored children in areas of high dietary iodine had lower incidences of thyroid cancer than children in iodine deficient areas. If this is the case, it runs counter to what is being found in Fukushima. Yamashita has declared the anomalies found in children’s thyroid to be no significant and has ordered rechecks to only happen every 2.5 years.  Then he sent a letter instructing medical doctors to not examine or treat children brought in with nodule concerns in Fukushima.

In the first-stage ultrasound examination, we have defined what needs the second-stage examination as nodules over 5.1 mm and cysts (non-solid but colloidal or liquid collection only) over 20.1 mm.  Thus, in addition to those with no abnormal findings, those with nodules smaller than 5 mm or cysts smaller than 20 mm have been decided not to be the subjects of further testing such as biopsies, or treatments.  We would imagine that you might receive a few inquiries or consultations from parents regarding these results.  Please explain to them well to make sure they understand that any further testing is not necessary before the next examination unless symptoms appear.

Also, this examination will be carried out every two years until age 20 and every five years from then on, leading to a long-term thyroid examination project.  Coordination with base hospitals all over the nation will be essential, and the examination will be widely publicized to the residents from now on.”

This has been interpreted as telling doctors to refuse to do any testing or treatment on children in Fukushima for thyroid nodules. Instead that they should be referred back to the government’s testing system of every 2 years that has set an arbitrarily high nodule size before intervention by the government would be taken. This creates a rather odd situation where people are no longer in charge of their health decisions, the government is now dictating who and when treatment or testing may be sought. This includes access to biopsies. Children in Fukushima who are now under Yamashita’s care if they want to be or not will not be able to access a biopsy test even if they have cysts or nodules just below the arbitrary government cut off. Doctors and activists in Japan have expressed concern about this issue that seems to take away the normal medical rights of children in the exposed regions of Japan.


Chernobyl Findings: 

What was found after Chernobyl generally showed a lower nodule rate than what we are seeing in Fukushima. The region around Chernobyl also tends to have a lower dietary intake of iodine based on what various thyroid studies have indicated.

One study 7 years after the Chernobyl accident found a nodule rate of 8-18% based largely on age, with testing done 7 years after the accident. Examination in this Chernobyl study was done by ultrasound as the first line of detection. The current study in Fukushima is being done with identical methods of ultrasound with biopsy as a second line of testing if deemed necessary. Based on all known factors the nodule issue at this time in Fukushima children should be lower than in Chernobyl. The estimated doses, dietary iodine and time since exposure all tell that the Fukushima children should have lower percentages than this Chernobyl children study. In Chernobyl many received protective iodine but contaminated milk was not excluded from the food supply. In Japan many children did not have access to protective iodine but contaminated milk was reportedly excluded from the food supply quickly. Japan blocked milk from Fukushima and Ibaraki from being sold for a time.

No pathological US findings in either village were found in children born after the accident. In the age group 0-9 years old at the time of the accident, the prevalence of thyroid abnormalities was 8.1% in the contaminated village compared to 1.6% in the uncontaminated village. In the age group 10-27 years the corresponding figures were 18.8% and 17.7%. Only 55% of the pathological US findings were detected by physical palpation.
CONCLUSION:The total prevalence of thyroid abnormalities was higher among children in the contaminated village. We recommend an active screening of young contaminated subjects with US, supplemented with fine needle biopsy.” 

Thyroid cancers have more than doubled due to Chernobyl with most being about 30 years of age post Chernobyl.

Thyroid doses estimated for some children in Fukushima ranged in one report from 5-35 mSv. Another estimated lifetime thyroid exposure to be 12-42 mSv. One study noted incredibly high levels of iodine-131 found in an adult.
The maximum I-131 activity detected in the thyroid of an adult was 1.5 kBq. Assuming the inhalation exposure took place for 4 hours on the afternoon of March 15th ….., we estimated that this person could inhale as much as 85 kBq of I-131.”

This shows the potential for incredibly high thyroid exposures in Fukushima that exceed Chernobyl doses. The Fukushima government testing has not admitted any such high levels but many doses are reconstructed if people were not given a thyroid scan in a timely manner due to iodine-131’s very short half life.
Effective Treatment & Screening Needed: 

The Japanese government study has declared children should only be rechecked every 2 years. General medical guidelines differ on screening intervals. Generally nodules without other risk factors and are under 1cm (10mm) can be monitored with repeated ultrasound examinations. Thyroid irradiation is a risk factor in standard medical protocol.
The following classifications apply to thyroid nodules per the Comprehensive Cancer Center in Ulm, Germany

T1 <2 cm, confined to the thyroid
T2 > 2-4 cm, limited to the thyroid
T3 > 4 cm or minimal extension beyond the thyroid

While Dr. Helen Caldicott suggested all nodules in children be biopsied rather than waiting two years, we did not come to the same conclusion that it would be the best process. A 3-6 month ultrasound screening period rather than the government mandated two years would have advantages for the patient. Combining the shorting testing intervals with using biopsy for any nodules that are growing rapidly or over 1cm (10mm) in size would give better oversight without the undue risk of a large number of biopsies. Biopsies are done with a small needle but with any minor procedure it comes with a small level of risk and discomfort for the patient. These biopsy protocols also some with the caveat that other thyroid complications such as hyperthyroidism, hypothyroidism and auto-immune thyroid disorders should be tested for and ruled out first.
Many thanks to all the researchers at SimplyInfo without them this article would not have been possible.


2001 Yamashita et al study

Yamashita letter with translation

Fukushima thyroid exam results with translation

Thyroid ultrasound findings 7 years after the Chernobyl accident. A comparative epidemiological study in the Bryansk region of Russia.

Post Chernobyl Thyroid incidence

Fukushima children thyroid doses 

Fukushima adult & child thyroid doses

Reports from citizen scientists in Fukushima via Safecast

Thyroid diagnostic protocols

Ulm Cancer Center thyroid cancer protocols

TMN classification of tumors

Caldicott suggestion of biopsy

General thyroid information

Chernobyl exposures & milk

Fukushima milk restrictions

Majias review of study on exposure

This article would not be possible without the extensive efforts of the SimplyInfo research team
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