Evaluation of (137)Cs body burden in inhabitants of Bryansk Oblast, Russian Federation, where a high incidence of thyroid cancer was observed after the accident at the Chernobyl nuclear power plant.

To determine the current risk of internal radiation exposure after the Chernobyl accident, the (137)Cs body burden of the inhabitants of Bryansk Oblast, Russian Federation was evaluated, from 1998 to 2008. The study population is composed of 84 666 people who visited Bryansk No. 2 Hospital. A whole-body counter was used for measurement of (137)Cs body burden. (137)Cs concentration was significantly higher in the late period during the study and showed seasonal variation, suggesting that inhabitants may have consumed contaminated forest products. However, people with high annual exposure doses were quite rare during all years of the study. In conclusion, although internal radiation exposure from (137)Cs continues to this day in Bryansk Oblast, the annual exposure dose is low in almost all inhabitants. Because of the long half-life of (137)Cs, the long-term follow-up is necessary to monitor the health status and relieve the anxiety of the inhabitants around Chernobyl.