Assessment of radioactivity level and associated radiological hazard in riverbed samples within industrial areas

Terrestrial gamma radiation is one of the major outdoor radiation exposures to the general public that varies substantially based on the type and geological properties of the soil. The objective of this study is to evaluate the naturally occurring radioactive materials (NORMs) distribution and assess the hazard parameters in the riverbank soil within various industrial zones in the densely populated Dhaka and Chattogram cities of Bangladesh. The mean activities of ²²⁶Ra (37 ± 3), ²³²Th (58 ± 4), and ⁴⁰K (1129 ± 18) Bqkg^-1 in the assessed soil samples were found to be slightly higher than the world average values 32, 35, and 420 Bqkg^-1, respectively. The mean radium equivalent activity (207.49 Bqkg^-1) and the external and internal hazard indices were within the recommended limits of 370 Bqkg^-1 and <1, respectively. The mean absorbed dose rate (99.47 nGyhr^-1), annual effective dose (0.12 mSva^-1), ELCR (4.27 × 10^-4), and gamma level index (1.58) exceeded the world average values 59 nGyhr^-1, 0.07 mSva^-1, 2.9 × 10^-4, and 1 respectively. However, the studied areas are safe from a radiological viewpoint with no radiation health hazard to the people. The results of this study can be utilized to produce factual baseline data for future studies.