Measurement of natural radioactivity and its health hazards associated with the use of different branded cement samples collected from different manufactures in Dhaka city using gamma spectrometry

The radioactivity of naturally occurring radionuclides 226Ra, 232Th, and 40K was determined in thirteen cement samples collected from different manufactures of Dhaka city. The measurement was performed by gammaray spectrometry system using high purity germanium (HPGe) detector. The average activity of 226Ra, 232Th, and 40K in cement samples are fon und to be 30.23±15.04 Bqkg-1, 20.10±11.76 Bqkg-1 and 145.27±24.14 Bqkg-1, respectively. The average values of radium equivalent activity (Raeq), absorbed dose rates (D), internal hazard and external hazard index (Hex), and annual effective dose equivalent are 370 Bqkg-1, 0.27, 0.18, and 27.99 nGyh-1, respectively. The average annual effective dose is found 0.13 mSvy-1, which is less than the recommended value (1 mSvy-1) by the International Commission on Radiological Protection (ICRP-60, 1990), as the maximum permissible annual effective dose to the members of the public. The present study results are discussed and compared with those reported in similar studies and with internationally recommended values. No artificial radioactivity was found in the present study. The results show that the analyzed cement samples do not pose any significant radiation hazard from naturally occurring radionuclides 226Ra, 232Th and 40K reported here and also considered safe for use in buildings construction. J. Bangladesh Acad. Sci. 45(1); 95-104: June 2021

Outdoor measurements of thoron progeny in a 232Th-rich area with deposition-based alpha track detectors and corrections for wind bias

Radon and thoron progeny are important contributors to dose from naturally occurring radionuclides, especially in high background areas and with naturally occurring radioactive material (NORM) legacy sites. Due to the short half-life of thoron, measurements of thoron progeny with a longer half-life should be used for risk and dose assessment. Deposition-based alpha track detectors for such progeny are, however, biased by air movement, especially outdoors where winds may be strong but variable. We used deposition detectors for thoron progeny and radon progeny, as well as alpha track gas detectors for 220Rn and 222Rn, outdoors within the Fen complex in Norway, an area with both elevated levels of naturally occurring radionuclides and NORM legacy sites. Different detector types were used and showed different results. We measured airflow along deposition detectors during deployment to assess wind bias and used statistical models to attain location-specific sheltering factors. These models assess how explanatory terms like point measurements with anemometer, predicted airflow along detectors, and levels of 220Rn and 222Rn explained variation in deposition detector measurements of TnP and RnP. For all the detector types, unrealistically, high equilibrium values (F) were found between progenitor noble gas and progeny before correcting for wind bias. Results suggest a magnitude of wind bias on TnP deposition detectors being a fraction of 0.74–0.96 (mean: 0.87) of the total measurement.

RADIOLOGICAL ASSESSMENT OF GRAINS, VEGETABLES, FRUITS AND TUBER CROPS CULTIVATED IN OKEMESI TOWNSHIP, EKITI STATE, NIGERIA

Exposure to radiation is a natural phenomenon in the human environment. This is received from naturally occurring radionuclides in water, air, soil and food. Ingestion is one of the two major pathways through which these nuclides enter the human systems. Radiological assessment of fruits, vegetables, grains and tuber crops cultivated and consumed in Okemesi township, Ekiti State has been carried out using a 76mm by 76mm lead-shielded Sodium Iodide detector (NaI(Tl)) located at the Centre for Energy, Research and Development (CERD), Obafemi Awolowo University, Ile-Ife, Nigeria. The mean activity concentration of the radionuclides in the food samples was 155.76 ± 14.22 Bqkg-1 for 40K, 8.00 ± 0.24 Bqkg-1 for 238U and 7.39 ± 0.21 Bqkg-1for 232Th.The value obtained for Annual Effective Dose due to intake of the food crops (Ding) ranged from 104.32 to 687 µSv yr-1 while values for Excess Lifetime Cancer Risks (ECLR) ranged from 0.365 t0 2.407. Although the radioactivity levels in the food crops were lower than the world-wide limits, some values obtained for the AED and the ELCR were significantly higher than the recommended limits of UNSCEAR 2000. The rank order of Ding and ELCR in the food types was tubers ? fruits ? vegetables ? grains. Consumption of food cultivated in the area over a long period of time may induce a degree of health risks which should not be overlooked.