226Ra concentration in the teeth of habitants of areas with high level of natural radioactivity in Ramsar

The level of natural radiation in some regions of Ramsar, a northern coastal city of Iran, is known to be among the highest levels of natural radiation in the world. Ra-226 existing in high concentrations in the soil of this region is washed by underground water and transferred to the surface. In this way, Ra-226 enters the food chain of residents and substitutes within the hard body tissues of humans. Ra-226 is one of the so-called bone seekers as its metabolic processes in the human body are similar to calcium and remains in hard tissues of body because of its long half-life, and being an alpha emitter causes dangerous effects on human health. The purpose of this study is to determine the concentration of Ra-226 in the teeth of residents of these high-level natural radiation areas, compared with a control group. Thirteen teeth in five groups were studied as the case group and thirteen teeth in five corresponding control groups were inspected. The mean values of the activity of Ra-226 in the case group and in the control group were 0.32 and 0.18 mBq g(-1), respectively. (c) 2006 Elsevier Ltd. All rights reserved.