Contamination from possible solar light exposures in ESR dosimetry using human tooth enamel

Electron spin resonance (ESR) measurement data of 98 teeth from atomic-bomb survivors who received various radiation doses were analyzed in terms of possible solar light exposure by tooth position. Each tooth was divided into buccal and lingual parts for independent ESR measurement. We found that average buccal doses were larger than their corresponding lingual doses by 0.48 +/- 0.30 Gy (first incisors), 0.33 +/- 0.38 Gy (second incisors), 0.20 +/- 0.23 Gy (canines), 0.24 +/- 0.26 Gy (first bicuspids), 0.17 +/- 0.51 Gy (second bicuspids) and 0.04 +/- 0.18 Gy (large molars and wisdom teeth). Such a clear declining trend following tooth position in the mouth is readily appreciated as due to solar light exposures. Comparisons of lingual doses of multiple teeth from the same five donors suggest that lingual doses of first incisors were also overestimated by 0.34 +/- 0.18 Gy. From the results presented, we deduce that the buccal doses of first incisors are, on the average, overestimated by nearly 0.8 Gy. Therefore, use of front teeth for biodosimetry requires special caution. How to estimate the contribution from exposure to solar light in ESR biodosimetry is discussed.