Preserving Deciduous Teeth Network (PDTN) 

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Philosophy of Preserving Deciduous Teeth Network

1. Name

This initiative is called ''Preserving Deciduous Teeth Network“ .

It aims to create a nationwide network of people contributing their children's shed deciduous teeth, which we will examine to determine the concentration of Strontium-90 deposited within them

2. Background

As a result of the TEPCO Fukushima Daiichi Power Plant accident, significant amounts of artificial radioactive materials were released into the environment, contaminating the atmosphere, waters (groundwater, rivers, lakes and marshes, oceans), soil, natural ecosystems on a global scale. At the Fukushima site, large amounts of groundwater flow into the damaged containment buildings where it mixes with severely contaminated water and then runs off into the sea.

We are concerned that the radioactive fallout spreading into the environment from the Fukushima Daiichi Power Plant could affect the health of humans. Levels of internal radiation exposure have been and are being measured by whole-body counters. However, a whole-body counter can only detect γ-rays, and cannot measure β-ray nuclides, such as Strontium-90 (Sr90).

Inhaled or ingested Strontium-90 is absorbed into bones where it accumulates and is retained for decades. Sr-90 can cause leukemia, immunodeficiency and other non-cancer diseases. American studies have shown that Sr-90 concentrations in deciduous teeth correlate strongly with the incidence of cancer and leukemia in children.(*1) It takes less than ten months for a fertilized egg to form a human body. The cells in a growing organism are very sensitive to radiation and, therefore, embryos and children are much more likely to be affected by radiation than adults.

Atmospheric nuclear weapons tests performed in the 1950s to the 1960s, caused the release of artificial radionuclides, including Strontium-90. It was carried around the globe by atmospheric circulation and reached Japan, where Sr90 fallout was measured in various places in the country. Simultaneously, surveys of deciduous teeth were conducted, as it was already known that Sr90 is readily absorbed into bones and teeth. The survey results confirmed that the amount of radioactive fallout correlates well with Sr90 levels in the deciduous teeth. Also, Sr90 levels in the teeth differed depending on the type of nutrition the infants received breast milk or formula or mixed (breast milk and formula)(*2) Similar research results were found in European and US countries.(*3)

After the Fukushima catastrophe Japanese researchers conducted surveys on the distribution of artificial radionuclides in animals' bones and deciduous teeth. Results from those surveys showed that high levels of Strontium-90 were present especially in the teeth of young animals, such as cattle, pigs, field mice and monkeys. Furthermore, it became clear that Sr90 levels detected in the animals correlate with the contamination levels of their habitats. (*4)

It is quite possible that the same thing is happening to humans. That is why we have been wanting to conduct surveys on Sr-90 levels in deciduous teeth. However, neither the Japanese government nor the Oversight Committee for the Fukushima Health Management Survey has responded to such requests. Furthermore, they dismissed a link between the unprecedentedly high incidence of pediatric thyroid cancer in Fukushima and radiation: ''It has nothing to do with the effects of radiation.''

What we need now is to conduct thorough investigations on artificial radioactive materials spread from the crippled Fukushima Power Plant into the environment and to determine the health effects caused by them.

3. Objectives And The Way Forward

We wish to exercise all our powers to protect the lives and the health of the affected population, especially those of the children. They should not be exposed further to any radiation. Our ultimate goal is to acknowledge and safeguard their rights to move away from dangerous, contaminated areas and to live in a healthy environment free from radiation risks.

In order to achieve this goal, we concluded after extended discussions that the most appropriate strategy would be to preserve the shed deciduous teeth to determine the concentration of Sr90 in them. This will help us provide some important evidence to prove internal radiation exposure.

Deciduous teeth begin to form when the embryo is about five to six weeks old. During the prenatal period, Sr90 can be absorbed into teeth and bones of the fetus through the umbilical.

The majority of infants sprout their first tooth when they are six to eight months old, and the deciduous teeth begin to loosen and fall out starting at about age four.

Sr-90 will remain in the shed teeth for a long time since it has a half-life of 29 years. Once the deciduous teeth are preserved, we can measure contamination-levels of Sr-90 whenever it is necessary.

Based on the results of our surveys we will determine the occurrence/levels of radiation exposure and analyse the health effects induced by it. The outcomes, such as supporting data and the results of analyses, will be used to make our recommendations to the citizens, the Japanese Government and the municipalities with the aim of initiating more extensive surveys and taking measures necessary to avoid further radiation exposure.

4. Management Structure

(1)The activities of the 'Preserving Deciduous Teeth Network' will be directed by a Steering Committee.

The Steering Committee will decide on the most appropriate approach to carrying out the Network's activities, establishing measuring facilities, setting budgets and so on.

(2)Members of the Steering Committee:

Chihiro Ichihara, Shigeharu Takai, Hiroshi Terao, Shoko Ohnuma, Tatemasa Fujino, Shin Takaki, Noriyuki Nakasuga, Eisuke Matsui, Gensuke Tokoro, Kenji Minoura, Junichi Ohnuma, Masumi Wakaoka, Kumi Ono, Yoko Yasuda, Koji Goto, Kazuko Matsui, Kaoru Hoshino


Chihiro Ichihara, Shigeharu Takai, Hiroshi Terao, Gensuke Tokoro, Shoko Ohnuma, Tatemasa Fujino,
Eisuke Matsui


Mail Address:
- Gifu Research Institute for Environmental Medicine:
 〒502-0017 Nagaraobusa 878-16, Gifu-City, Gifu Prefecture
 TEL:058-296-4038  FAX 058-296-3903
- Kyodo Dental Surgery:
 〒270-2253 Nippori 1-6-1, Matsudo-City, Chiba Prefecture
 TEL:047-711-5201 FAX 047-711-5202

(5)Project Plan and Finance:

- Our project will be financed through various subsidies and contributions from the general public.

- We intend that our organisation should be recognized as an NPO Corporation (incorporated nonprofit organisation). Therefore, our approach to the management of the Network ( e.g. project planning, budget, reports, settlements of accounts, etc. ) will follow the rules of NPO corporations.

- We will hold a general meeting, at which our findings, among other things, will be reported.

5. Measuring System and Facilities

■ Measuring object : Shed deciduous teeth

■ We collect the shed teeth accompanied by a 'Personal Record Card', which is to be completed by either the donor of the teeth or his/her guardian. The 'Personal Record Card' indicates: name of the donor, age, address (at the time of the Fukushima Catastrophe), Primary Teeth Chart (to identify the teeth) and so on.

■ A receipt will be issued and given to each donor.

■ Collected deciduous teeth will be tagged and securely stored to protect personal information.

■ Donors' agreements will be sought prior to using the results of the surveys of their teeth for analysis and research.

◇Initial Investment ◇
50,000,000 Yen

◇Measuring Methodology◇

 ・An adaptation of the method employed by Basel Kantonales Labor in Switzerland will be used.

◇Commencement Date and Researching Period ◇

 ・Scheduled commencement date March, 2017
 ・The initial research period will be five years with a long-term aim of 100 years.

Promoters and Supporters

Studies on the accumulation of radionuclides (strontium, plutonium)emitted from the Fukushima No.1 nuclear power plant accident into human milk teeth (in Japanese)
An unexpected rise in strontium-90 in US deciduous teeth in the1990s:
- Research Survey Results of Health Effects by radiation conducted by Nuclear Safety Research Association:

- Measurement of Strontium- and Cesium- Concentration in Abandoned Cattle in the Evacuation Zone of the Fukushima Daiichi Nuclear Power Plant by Hidekazu Nihei (in Japanese)