Radioactivity Levels and Health Risks due to Radionuclides in the Soil of Yalova, Northwestern Turkey

Naturally occurring radionuclide of terrestrial origin (also called primordial radionuclide) are present in various degrees in all media in the environment, including the human body itself. Their concentrations in environment decrease continually by decaying. The main objective of this study is to evaluate the radioactivity levels and health risks due to terrestrial radionuclide in soil of Yalova, northwestern Turkey. For this purpose, activity concentrations of radionuclide in soil and the environmental outdoor gamma dose rates (terrestrial and cosmic) have been investigated in the city of Yalova. In addition, maps for the radionuclide activity concentrations of soil and the outdoor gamma dose rates distributions have been plotted for the region. The average activities of radionuclide, 238 U, 232 Th, 226 Ra, 40 K, and 137 Cs in the soil were determined as 17.95 (8.5-37.3) Bq/kg, 26.87 (3.8-43.9) Bq/kg, 22.36 (8.3-41) Bq/kg, 419.32 (197.1-950.0) Bq/kg, 2.53 (0.5-13.4) Bq/kg, respectively, in the region. The average outdoor gamma dose rates due to terrestrial and cosmic radiations were found to be 49 nGy/h and 35 nGy/h with the total of 84 nGy/h outdoor gamma exposure rate in the region. Annual effective dose due to environmental outdoor gamma radiation exposures was determined as 103 nSv with the excess lifetime cancer risk of 0.042 x 10-2 in the region. The results of the study were discussed with the studies done in the close cities and the worldwide averages.