Estimation of birth year by radiocarbon dating of tooth enamel: Approach to obtaining enamel powder

Atmospheric radiocarbon (C-14) levels increased from 1955 to 1963 due to atmospheric nuclear weapon tests, and then decreased. As C-14 accumulates in human tooth enamel while the enamel is being formed, C-14 can be used to estimate the birth year of unidentified bodies. Measurement results of C-14 content in tooth enamel using accelerator mass spectrometry vary depending on the enamels 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-14 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-14 measurement of pulverized teeth.