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Accumulation of a Radioactive Isotope in Children’s Shed Deciduous Teeth Used to Estimate Radiation Exposure from Nuclear Testing and Accidents, Then and Now

March 11, 2016

A 1961 paper published in the journal Science showed that analysis of deciduous teeth collected as part of a larger project called the “Baby Tooth Survey” could provide a practical method for monitoring strontium-90 (Sr-90) and radiation exposure.1  Sr-90 is a radioisotope that, if ingested in food or water, can be incorporated into bone and teeth structures, similar to calcium.2  Although Sr-90 is not a naturally occurring substance, it has been found in the environment following fallout from the nuclear testing that occurred in the 1950s and 1960s and also in nuclear reactor waste.2, 3  The researchers used liquid scintillation spectrometry to analyze shed deciduous teeth, showing that St. Louis children born in 1954 had four times as much Sr-90 in their teeth as children born in 1951, and was likely related to exposure to fallout from nuclear testing.1  In 2011, researchers using a small sample of teeth originally collected as part of the “Baby Tooth Survey,” but never used, performed a case-control study to estimate cancer risk of fallout exposure.4  The authors found that the tooth donors who died of cancer by age 50 years had more than twice the average Sr-90 levels of donors who were still alive at age 50 years (significantly elevated Sr-90 concentration among those who died of cancer by age 50 [odds ratio 2.22; p<0.04], versus those still alive at age 50 [odds ratio 0.72; p=NS]).4  Although these data suggest an association between early cancer mortality and exposure to Sr-90, the observational design of the study cannot establish causality.

In 2015, a group of experts in Japan formed the “Preserving Deciduous Teeth Network” (PDTN),5 which is asking parents to contribute children’s baby teeth to help study radiation exposure in the aftermath of the 2011 Fukushima Daiichi nuclear accident.5, 6 The intent of the work of the PDTN is to measure the levels of Sr-90 in the shed deciduous teeth of children who were in utero at the time of the Fukushima nuclear disaster 5 years ago.6  Following the Fukushima Daiichi nuclear accident, large amounts of radioactive materials were released into the environment, where they contaminated soil and groundwater.6 It is hoped that evaluation of the amount of Sr-90 in the tooth samples can help estimate radiation exposure following the disaster.6  So far, the PDTN has received donations of approximately 500 baby teeth, and has commissioned a Swiss testing facility to measure the amount of Sr-90 radioactivity in the tooth samples; however, in 2017, PDTN plans to establish its own testing facility in central Japan.5  Formal research will commence in March 2017 and the initial research period will be five years.6

References

  1. Reiss LZ. Strontium-90 absorption by deciduous teeth. Science 1961;134(3491):1669-73.
  2. National Center for Environmental Health (NCEH) /Agency for Toxic Substances and Disease Registry (ATSDR) National Center for Injury Prevention and Control (NCIPC). Radioisotope Brief: Strontium-90. Centers for Disease Control and Prevention (CDC). http://emergency.cdc.gov/radiation/isotopes/strontium.asp. Accessed March 9, 2016.
  3. U.S. Nuclear Regulatory Commission. Backgrounder on Radiation Protection and the "Tooth Fairy" Issue (rev. 8/2015).  December 2004. http://www.nrc.gov/reading-rm/doc-collections/fact-sheets/tooth-fairy.html. Accessed March 8, 2016.
  4. Mangano JJ, Sherman JD. Elevated in vivo strontium-90 from nuclear weapons test fallout among cancer decedents: a case-control study of deciduous teeth. Int J Health Serv 2011;41(1):137-58.
  5. Dentist urges people to keep kids' baby teeth to study Fukushima radiation exposure. The Mainchi March 7, 2016. http://mainichi.jp/english/articles/20160307/p2a/00m/0na/015000c. Accessed March 8, 2016.
  6. Preserving Deciduous Teeth Network (PDTN). http://pdn311.town-web.net/english/index.html. Accessed March 8, 2016.

Prepared by: Center for Scientific Information, ADA Science Institute

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Science in the News is a service by the American Dental Association (ADA) to its members to present current information about science topics in the news. The ADA is a professional association of dentists committed to the public's oral health, ethics, science and professional advancement; leading a unified profession through initiatives in advocacy, education, research and the development of standards. As a science-based organization, the ADA's evaluation of the scientific evidence may change as more information becomes available. Your thoughts would be greatly appreciated.