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.

A study on measuring the 222Rn in the Buriganga River and tap water of the megacity Dhaka.

Radon (222Rn), an inert gas, is considered a silent killer due to its carcinogenic characteristics. Dhaka city is situated on the banks of the Buriganga River, which is regarded as the lifeline of Dhaka city because it serves as a significant source of the city's water supply for domestic and industrial purposes. Thirty water samples (10 tap water from Dhaka city and 20 surface samples from the Buriganga River) were collected and analyzed using a RAD H2O accessory for 222Rn concentration. The average 222Rn concentration in tap and river water was 1.54 ± 0.38 Bq/L and 0.68 ± 0.29 Bq/L, respectively. All the values were found below the maximum contamination limit (MCL) of 11.1 Bq/L set by the USEPA, the WHO-recommended safe limit of 100 Bq/L, and the UNSCEAR suggested range of 4-40 Bq/L. The mean values of the total annual effective doses due to inhalation and ingestion were calculated to be 9.77 µSv/y and 4.29 µSv/y for tap water and river water, respectively. Although all these values were well below the permissible limit of 100 µSv/y proposed by WHO, they cannot be neglected because of the hazardous nature of 222Rn, especially considering their entry to the human body via inhalation and ingestion pathways. The obtained data may serve as a reference for future 222Rn-related works.