RESUMEN
The main aim of this study was to evaluate gamma radiation level in the mineral hot springs of Ardabil province in Iran. In addition, the cancer risk of gamma radiation was assessed for swimmers. Natural gamma radiation was measured using Ion Chamber Survey Meter 451B in 22 springs throughout the province. Gamma was measured at 20 cm and 100 cm above the ground level in 15 locations of each spring. Excess lifetime cancer risk was calculated to investigate the risk of exposure to gamma radiation. The highest and lowest annual absorbed dose rate of gamma were found to be 1.17(10-3) and 1.99(10-3) Sv/y at the height of 20 cm above the ground level and 5.26(10-4) and 1.52(10-3) Sv/y at the height of 100 cm above the ground level, respectively. Excess lifetime cancer risk ranged from 4.57(10-4) to 7.76(10-4) at the height of 20 cm and from 2.06(10-4) to 5.94(10-4) at the height of 100 cm which are lower than global average of 1.45(10-3) declared by the United Nations. Although the risk level in this study is lower than the global average, protective and preventive measures should be considered by individuals and authorities in these areas to reduce the effects of gamma radiation on the health of the swimmers.