Saitoh Hisako, Moriya Toru, Takeyama Mirei, Yusa Kazuyuki, Sakuma Ayaka, Chiba Fumiko, Torimitsu Suguru, Ishii Namiko, Sakurada Koichi, Iino Mitsuyoshi, Iwase Hirotaro, Tokanai Fuyuki
Department of Legal Medicine, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba, 260-8670, Japan.
Center for Accelerator Mass Spectrometry, Yamagata University, 19-5 Kanakame, Kaminoyama, 999-3101, Japan.
J Forensic Leg Med. 2019 Feb;62:97-102. doi: 10.1016/j.jflm.2019.01.013. Epub 2019 Jan 29.
Atmospheric radiocarbon (C) levels increased from 1955 to 1963 due to atmospheric nuclear weapon tests, and then decreased. As C accumulates in human tooth enamel while the enamel is being formed, C can be used to estimate the birth year of unidentified bodies. Measurement results of C content in tooth enamel using accelerator mass spectrometry vary depending on the enamel's sample site. To address this problem, a method for equalizing samples using a pulverizer was considered in this study. Regarding the tube and cone used as the pulverizer, (1) a polycarbonate tube and stainless steel cone, (2) a stainless steel tube and cone, and (3) a tungsten carbide tube and cone, were compared. In (1), the modern carbon ratio was approximately half that of the normal ratio of 100 pMC, with which accurate dating was impossible, and in (2), a high background value was obtained for IAEA-C1, which was pulverized using a reusable tube and cone. In (3), the C content for IAEA-C1 pulverized using reusable tube and cone, which was washed with quartz sand, was 0.31 ± 0.01 pMC. This result did not show any problems regarding background value. Therefore, the use of tungsten carbide products and washing with quartz sand is recommended for C measurement of pulverized teeth.
由于大气层核武器试验，1955年至1963年期间大气中放射性碳（C）水平上升，随后下降。由于碳在人类牙釉质形成过程中会积累，因此碳可用于估计身份不明尸体的出生年份。使用加速器质谱法测量牙釉质中碳含量的结果会因牙釉质的取样部位而有所不同。为了解决这个问题，本研究考虑了一种使用粉碎机使样本均匀化的方法。对于用作粉碎机的管和锥，比较了（1）聚碳酸酯管和不锈钢锥、（2）不锈钢管和锥以及（3）碳化钨管和锥。在（1）中，现代碳比率约为正常比率100 pMC的一半，无法进行准确测年；在（2）中，使用可重复使用的管和锥粉碎的国际原子能机构 - C1获得了较高的背景值。在（3）中，使用可重复使用的管和锥粉碎并经石英砂洗涤的国际原子能机构 - C1的碳含量为0.31±0.01 pMC。该结果在背景值方面未显示任何问题。因此，建议使用碳化钨产品并经石英砂洗涤来对粉碎后的牙齿进行碳测量。
