Determination of radioactivity levels of soil samples and the excess of lifetime cancer risk in Rize province, Turkey

Background: Turkey, especially the northern part of it, was one of the countries which were contaminated by the Chernobyl accident.  Rize is a city located in the Northeastern district of Turkey which was heavily influenced by the Chernobyl nuclear accident. Materials and Methods: In this study, the activity concentrations of natural (226Ra, 232Th, 40K) and artificial (137Cs) were measurements in soil samples  collected from 132 different points in Rize province of Turkey using gamma spectrometry with a high-purity germanium detector. Results: The average activity concentrations of 226Ra, 232Th and 40K were found to be 85.75±11.77, 51.08±9.42, and 771.57±37.65 Bq/kg in soil samples, respectively. In order to evaluate the radiological hazard of the natural radioactivity, radium equivalent activity (Raeq), representative level index (Iγr), the external hazard index (Hex), the total absorbed dose rate (D), the annual effective dose equivalent (AEDE) and excess life time cancer risk (ELCR) have been calculated and compared with the internationally approved values. Conclusion: The outdoor air absorbed dose rates (D) due to terrestrial gamma rays for soil have been calculated because of agricultural area and living in the surrounding. It is important to determine background radiation level in order to evaluate the health hazards. Annual effective gamma doses and the lifetime risks of cancer were higher than the world’s average. Moreover compared to the World’s average, the lifetime risk of cancer doubled for most of the localities.