A REVIEW ON VARIATION OF NATURAL RADIOACTIVITY ALONG THE SOUTHEAST COAST OF TAMIL NADU FOR THE PAST 4 DECADES (1974-2016)

Comparison of environmental radioactivity in road dust between a city and a megacity: geo-environmental evaluation, health risks, and potential remediation

This pioneering study represents a comprehensive comparative analysis of naturally occurring radioactive materials (NORMs: 226Ra (≈238U),232Th, 40K) on the roadside dust samples collected from a coastal city (Khulna) and a highly urban megacity (Dhaka), Bangladesh. The corresponding radioactivity was calculated based on Instrumental Neutron Activation Analysis of elemental abundances (uranium [U], thorium [Th], and potassium [K]). Averagen=30 radioactivity levels of 226Ra (≈238U), 232Th, and 40K in the road dust of Khulna city were 46.82 ± 24, 74.79 ± 25, and 541.14 ± 160.8, whereas in Dhaka city, they were 84.4 ± 13, 126 ± 11, and 549 ± 48 (Bq.kg-1), respectively. Khulna city had 1.3, 2.5, and 1.4 times greater 226Ra (≈238U), 232Th, and 40K radioactivity than the global average values, respectively. For Dhaka city, the following values were 2.42, 4.2, and 1.4 times elevated. The levels of radioactivity in Dhaka city are significantly higher than those in Khulna city; however, both cities have exceeded the world average values. The mechanisms for the enrichment and dispersion of NORMs from their fundamental source (surface soil) were studied, considering waterlogging, relative solubility-controlled leaching and translocation, climate conditions, and aerodynamic fractionations (dry and wet air deposition). The computation of standard radiological indices indicates risks to human health. Respiratory harm can be inflicted by α-particles originating from the radioactive decay products of 232Th and 238U. In addition to public awareness, policymakers should prioritize limiting the evolution of dust particles to mitigate the associated health risks.

Radionuclides' Dispersion from Coal-Fired Brick Kilns: Geo-Environmental Processes, Potential Risks and Management

In order to investigate the distributions and possible dispersion mechanism(s) of naturally occurring radioactive materials (NORMs: 226Ra, 232Th, and 40K) from coal-based brick kilns, a systematic set (n = 60) of coal, ash, surface-soil, and subsurface soil samples were analyzed. High-quality analytical data of U, Th and K obtained from HPGe detector and TRIGA Mark-II research reactor-based neutron activation analysis were converted to the corresponding radioactivities. Average (n = 10) radioactivities of 226Ra, 232Th, and 40 K in coal samples were 15.6, 16.7, and 145.5 Bq.kg-1, respectively, where only 40 K surpassed the corresponding global mean value. Average (n = 10) radioactivities of 226Ra, 232Th, and 40 K in ash samples were 62.7, 88.5, and 521 Bq.kg-1, respectively, where only 226Ra was within the established limit. In soil samples, average (n = 40) activities of 226Ra, 232Th, and 40 K were 62.7, 95.1, and 641 Bq.kg-1, respectively, which have surpassed the corresponding worldwide mean values. The observed differences in activity levels between soil samples collected near and far from the kilns, as well as between topsoil and subsoil samples, suggest the presence of distinct transport mechanisms for NORMs within the pedosphere. Dispersions of NORMs from the brick kilns to the ambient pedosphere are largely governed by aerodynamic convection and hydrodynamic leaching. These mechanisms are also influenced by geochemical mobility and relative solubility of NORMs, as well as factors such as rainfall patterns and wind-flow direction. Radiological indices invoke long-term carcinogenic-risks, whereas aerodynamic convection of finer particles (coal fly ash) from chimneys can cause significant health hazards to the nearby dwellers. Scientific processes as well as public awareness are essential to mitigate the risks.

Review and statistical analysis of activity values reported for coastal sands worldwide

The activity of natural radionuclides is unevenly distributed across the Earth's crust, with certain areas exhibiting significantly higher levels than others, known as High Background Radiation Areas (HBRAs). This study presents a statistical analysis of reported activity values for coastal sands globally. Through this statistical analysis, costal sands were classified into four categories based on their activity levels, providing a standardized framework to compare the natural radioactivity of these sands. This classification is a valuable tool for identifying populations exposed to different radiation levels, which is essential for the study of stochastic effects. The study proposes thresholds to define HBRAs as regions with activity values exceeding 203 Bq/kg for 238U, 517 Bq/kg for 232Th, or 960 Bq/kg for 40K. Regions with lower values are classified as NonHBRAs. Further subdivision of these categories resulted in four distinct regions: NonHBRA-, NonHBRA+, HBRA-, and HBRA+. The activity values for these subdivisions are 92 Bq/kg and 2,903 Bq/kg for 238U, 94 Bq/kg and 7,230 Bq/kg for 232Th, and 901 Bq/kg and 2,298 Bq/kg for 40K. By calculating the external dose rates from the reported activity data, a threshold of 357 nGy/h was identified as the dose boundary separating NonHBRAs from HBRAs. The values for the subdivisions resulted 101 nGy/h and 3,867 nGy/h. The study also explores the content of these natural radionuclides in relation to their bearing minerals and discusses correlations between the reported activity values and the characteristics of the sands. Additionally, the activity of the anthropogenic radionuclide 137Cs (reported values ranging from the detection limit to 63 Bq/kg) is examined.

Recommendations for reducing exposure to medical X-ray irradiation (Review)

With the increasing frequency of X-ray examinations in clinical medicine, public concern regarding the harm caused by exposure to X-ray radiation is also increasing. However, some physicians are not completely aware of the dangers of exposure to X-ray irradiation. Individuals specialized in this field, including physicians, have a better understanding of these dangers, which limits the use of X-rays in medicine. The present study aimed to address strategies for reducing the harm caused by exposure to medical X-rays and increase public awareness regarding X-ray radiation. Through a literature search and review, combined with the current status of clinical X-ray examination and the authors' professional experience, the present study highlights the importance of reducing X-ray exposure, and proposes several specific recommendations and measures for reducing the frequency or dose of X-ray irradiation. On the whole, the finding discussed in the present review suggest the minimal use of medical X-ray examinations and that alternative tests should be selected whenever possible. When medical X-ray screening and treatments are necessary, the risk-benefit ratio should be assessed, possibly aiming to achieve avoidable exposure. Further attention should be paid to protect sensitive glands and reduce the risks in children.