Assessment of Natural Radioactivity and Associated Radiation Hazards in Topsoil of Savar Industrial Area, Dhaka, Bangladesh

The radioactivity levels of naturally occurring radionuclides 226 Ra, 232 Th and 40 K in thirteen topsoil samples, collected from Savar industrial area of Bangladesh, were measured by gamma ray spectrometry system using a High Purity Germanium (HPGe) detector of 40% relative efficiency. The calculated average activity concentrations of 226 Ra, 232 Th and 40 K in the collected samples were 23.31 Bq.kg -1 , 42.24 Bq.kg -1 and 733.19 Bq.kg -1 , respectively. The average activity concentration of 232 Th and 226 Ra in the present study is lower than that of the world-wide average value but the concentration for 40 K is much higher than the world average of 420 Bq.kg -1 . The estimated average absorbed dose rate (D), the outdoor annual effective dose (E) and the external hazard index (H ex ) were found as 67.08 nGyh -1 , 0.08 mSvy -1 and 0.38 Bq.Kg -1 , respectively. The absorbed dose rate and outdoor annual effective dose are slightly higher than the world average value but the external hazard index is lower than that of the recommended value. The results of present study show that the soil of the study area is safe from radiological hazards and will not pose any harmful effect to the environment. The outcome of this study may provide valuable information about radiation hazard as well as may be useful as the baseline data in the monitoring of environmental radioactivity in the industrial zone under study.