L-Band Electron Paramagnetic Resonance Tooth Dosimetry Applied to Affected Cattle Teeth in Fukushima

Ichiro Yamaguchi,Harold M Swartz,Kazuhiko Inoue,Yasuhiro Nakai,Masahiro Natsuhori,Minoru Miyake,Chryzel Angelica B Gonzales,Hiroshi Yasuda

doi:10.3390/app11031187

Abstract

We applied a non-destructive tooth dosimetry technique using L-band electron paramagnetic resonance (EPR) to assess radiation doses in cattle due to the Fukushima Daiichi Nuclear Power Station (FDNPS) accident, which occurred 10 years ago. The radiation exposure of cattle in the area affected by the FDNPS accident was estimated retrospectively with X-band and L-band EPR devices. Characteristic radiation-induced EPR signals were obtained from the teeth of the cattle in Fukushima, confirming their exposure. The estimated doses to the teeth were found to be consistent with the dose trends estimated for individual cows, while considerable uncertainties were seen in the doses of some tooth samples. This variation might be due to errors in the accuracy of the method but also might reflect the actual exposure because the cattle may have been exposed to higher areas of radioactivity in their quest for food and/or due to irradiation from absorption of the isotopes with localization in or near the teeth. However, at a minimum, these results confirm that L-band EPR can be used for non-destructive qualitative assessment of radiation exposure to animals using their teeth, which could be very valuable. Possible causes of the uncertainties should be investigated to enhance the value of the use of this technique.

Highlights

Electron paramagnetic resonance (EPR) tooth dosimetry is an established method for evaluating the absorbed dose ionizing radiation by measuring the unpaired electrons to in-teeth samples [1]
Assuming that our assays of the amount of radioactive material in the teeth reflect the full amount of such deposits, we find that, the self-absorption dose—that is, the radiation dose to which a tooth is subjected via radionuclides, including radioactive Cs and 89Sr, 90Sr—was limited, perhaps to as low as 20 mGy, This difference of internal radiation dose from radioactive Sr is due to the difference in the amount of radioactive strontium released into the atmosphere in the case of the Techa River and the nuclear accident at Fukushima
The novel technique of L-band electron paramagnetic resonance (EPR) tooth dosimetry was successfully applied to cattle in the former evacuation zone affected by the Fukushima Daiichi Nuclear Power Station (FDNPS) accident, which occurred 10 years ago

Summary

Introduction

Electron paramagnetic resonance (EPR) tooth dosimetry is an established method for evaluating the absorbed dose ionizing radiation by measuring the unpaired electrons to in-teeth samples [1]. X-band EPR tooth dosimetry, which uses extracted teeth, has been used for atomic-bomb survivors of Hiroshima and Nagasaki [8] and residents of affected settlements due to radiation released into the environment [9]. This method was applied to some animals affected by the Chernobyl accident in 1986 [10] and the Fukushima Daiichi Nuclear Power Station (FDNPS) accident which occurred in March 2011 [11,12]

Methods

Results

Discussion

Conclusion