UNSCEAR Research Articles

A summary of updated UNSCEAR evaluations on medical and occupational exposures to ionising radiation and call for participation in UNSCEAR Global Surveys on radiation exposure.

This paper summarises key findings of United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) 2020/2021 Report on the evaluations of medical and occupational exposures to ionising radiation. Medical exposure remains by far the largest human-made source of radiation exposure of the population. In the period 2009-18, about 4.2 billion medical radiological examinations were performed annually, resulting in an effective dose per caput of 0.57mSv. The worldwide annual number of workers exposed to natural and human-made sources of ionising radiation is estimated to be ~24 million in the period 2010-14. About 52% of those were employed in the sectors that involve exposure to natural sources of radiation. The annual effective dose was estimated to be around 2.0mSv for workers exposed to natural sources (excluding radon exposure in workplaces other than mines) and 0.5mSv for workers exposed to human-made sources. It is important to motivate United Nations Member States to fully participate in UNSCEAR's global surveys on radiation exposure. Future surveys will be relevant and useful and adapted to changing data sources and uses of radiation across the world.

Evaluation of natural radioactivity levels and radiation hazards of Nkalagu limestone deposit, southeastern Nigeria.

Levels of natural radioactivity due to 40K, 232Th, and 226Ra in limestone deposits and corresponding surface soil samples from the Nkalagu community of Ebonyi State were investigated. Gamma spectroscopic analysis using a NaI (TI) detector was employed to measure the activity concentrations (ACs) of the natural radionuclides in the collected samples. The average AC of 226Ra, 232Th, and 40K was found to be 64.62 ± 11.63, 54.27 ± 8.52, and 313.06 ± 25.33Bq/kg, respectively, in limestone, whereas in the soil, the value was 60.80 ± 11.71, 44.97 ± 10.74, and 185.90 ± 18.20Bq/kg, respectively. Except for 40K, the obtained mean ACs of the radionuclides were in excess of the worldwide averages reported by the United Nations Scientific Committee on the Effect of Atomic Radiation (UNSCEAR). The mean value of Raeq, Hex, Hin, Iγ, and AUI was obtained as 166.33Bq/kg, 0.45, 0.62, 1.18, and 1.28, respectively, in the limestone, and 139.42Bq/kg, 0.38, 0.54, 0.98, and 1.12, respectively, in the surface soil. The radiation doses in limestone ranged from 120.78-168.89 nGyh-1 and 63.86-88.88 nGyh-1 for indoor and outdoor, respectively, whereas in the soil, the range was 104.47-129.77 nGyh-1 and 54.60-68.02 nGyh-1 for indoor and outdoor, respectively. The total annual effective dose ranged from 0.671 to 0.937 mSvy-1 with an average of 0.800 mSvy-1 in limestone and 0.579 to 0.720 mSvy-1 with an average of 0.667 mSvy-1 in the soil. Values of representative gamma index and activity utilization index, and indoor and outdoor radiation doses in limestone were above the recommended world average of ≤ 1, and 84 nGyh-1 and 59 nGyh-1, respectively, suggesting a restriction in the use of the limestone in construction of houses. The study therefore recommends that the use of limestone in building construction, especially in house interiors, should be discontinued.

Assessment of Activity Concentration and Health Hazards of Radiation Exposure in Soil from Mamara Jidda and Waja Tin Mining Sites in Northern Nasarawa State, Nigeria

Natural background radiation exposure is an inevitable occurrence on Earth, and humans are exposed to radiation in their surroundings whether consciously or unconsciously. However, increased artisanal and illegal mining could harm the local environment and increase background radiation levels, affecting the community's overall health. This study assessed the activity concentration of primordial radionuclides (226Ra, 232Th, and 40K) from soil samples obtained from Mamara Jidda and Waja tin mine sites in Nasarawa State, Nigeria, and its risk to human health. The gamma spectroscopy using a Sodium iodide-thallium activated detector was used to measure the activity concentrations of primordial radionuclides in the surface soils/sediments samples. The activity concentrations of 226Ra, 232Th, and 40K for Mamara Jidda and Waja were found to be within the range of 4 - 18 Bq kg-1, 41 - 105 Bq kg-1, and 524 - 717 Bq kg-1; 13 - 40 Bq kg-1, 75 - 134 Bq kg-1, and 591 - 882 Bq kg-1 respectively. The average values show that 40K and 232Th concentrations are above the recommended limit set by the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) in Mamara Jidda and Waja mine sites. The annual gonadal dose equivalent (AGDE), annual effective dose rate (AEDE), radium equivalent (Raeq), absorbed dose rate (D), and external hazard index (Hex) for Mamara Jidda and Waja were found to be 0.56 mSv yr-1, 0.10 mSv yr-1, 588.58 Bq kg-1, 78.26 nGy hr-1 and 0.46; 0.73 mSv yr-1, 0.13 mS yr-1, 742.74 Bq kg-1, 103.72 nGy hr-1 and 0.61 respectively. The AEDE and Hex are below the recommended safety limits. However, the high values of AGDE in both mining sites and D in Waja mine demonstrate that with continuous exposure to radiation, a significant genetic impact is eminent to the miners and inhabitants of these areas. Also, the Raeq values for both mines suggest that their soils are unsafe for use as building materials.

Direct measurement of indoor thoron and radon progeny and estimation of inhalation dose in three cities in Gabon: Comparison of the use of thoron typical and measured equilibrium factor values

This study focuses on public exposure to natural radioactivity caused by the inhalation of radon and thoron progeny in homes in Franceville, Moanda and Mounana in Gabon. The equilibrium factor (FTn) between thoron and its progeny was determined experimentally for a proper estimate of the effective dose. In order to assess internal exposure due to radon and thoron progeny, 150 passive radon-thoron discriminative detectors (RADUET) and thoron progeny monitors were deployed for about 3 months in the above-mentioned towns. The results of the measurements obtained showed that the average concentrations of thoron progeny (EETC) were 1.54 ± 0.08 Bq m−3, 3.05 ± 0.09 Bq m−3 and 1.84 ± 0.11 Bq m−3 in Franceville, Moanda and Mounana, respectively. The ranges of the measured thoron equilibrium factors were 0.004–0.710, 0.005–0.750, and 0.006–0.794 in Franceville, Moanda and Mounana, respectively. The arithmetic and geometric mean values were, respectively, 0.183 and 0.117 in Franceville, 0.184 and 0.122 in Moanda, and 0.221 and 0.140 in Mounana. The experimentally determined equilibrium factor (FTnexp) allowed us to compare the value of the experimentally determined effective dose with the theoretically determined one calculated using the equilibrium factor proposed by United Nation Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) 2000 report. FTnexp values were around 6–11 times greater than the UNSCEAR typical value. The ranges, arithmetic and geometric mean EERC values determined were 30.40–55.60 Bq m−3, 24.00 ± 0.90 Bq m−3 and 41.68 (1.00) in Franceville, 36.40–62.50 Bq m−3, 45.30 ± 0.70 Bq m−3 and 44.72 (1.00) in Moanda, and 35.00–90.00 Bq m−3, 50.00 ± 2.00 Bq m−3 and 48.50 (1.00) in Mounana. The mean values of the annual effective inhalation dose due to thoron progeny determined using FTnexp were 0.32 mSv (compared to 0.049 mSv), 0.63 mSv (compared to 0.103 mSv), and 0.39 mSv (compared to 0.055 mSv) in Franceville, Moanda and Mounana, respectively. The main conclusion of this study is that indirect estimations of thoron progeny concentrations considerably underestimate the estimation of the annual effective inhalation dose.

Evaluation of radioactivity levels and hazard indices of Th-232, Ra-226 and K-40 in sediment and water samples of Lake Victoria, Jinja, Uganda

This study evaluates the levels of natural radioactivity in sediment and water samples from Lake Victoria in Jinja, Uganda, with a focus on the radionuclides potassium-40 (40 K), radium-226 (226Ra), and thorium-232 (232Th). We investigated four distinct zones around the lake: fishing (Zone A), farming (Zone B), domestic/livestock (Zone C), and a control zone (Zone D). A total of 15 sediment samples and 15 water samples were collected and analyzed. Sediment samples were obtained using a gravity corer, with a maximum penetration depth of 50 cm. 40 K ranged from 170.479 to 524.883 Bqkg−1 across all zones, 226Ra ranges from 1.51 to 56.78 Bqkg−1 across all zones, and 232Th ranges from 18.18 to 73.10 Bqkg−1 across all zones. 40 K concentrations were highest in the farming zone, likely due to the use of nitrogen, phosphorus, and potassium (NPK) fertilizers. 226Ra and 232Th levels were also elevated in the farming zone, suggesting potential contributions from phosphate fertilizers. Absorbed dose rates varied across the zones, ranging from 28.33 to 58.17 nGyh-1. The measured absorbed dose rates across all zones were within the global average of 59 nGyh−1. The effective annual dose rate ranged from 0.35 to 0.91 mSvy−1 across all zones. Effective annual dose rates did not exceed the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) recommended limit of 1 mSv y−1, indicating low risks to public health from sediment radioactivity. The external index was below the safety threshold, suggesting minimal health risks. In water samples, gross alpha and beta activity concentrations were analyzed. Zone B had the highest average alpha activity concentration (0.64 BqL−1) and beta activity concentration (0.72 BqL−1), while Zone A had the lowest for both alpha (0.16 BqL−1) and beta (0.25 BqL−1) activity concentrations. Gross beta activity was generally higher than gross alpha activity, reflecting potential anthropogenic influences. Most water samples were within the UNSCEAR recommended limits for drinking water quality, except in areas affected by agricultural runoff. This study demonstrates that while the sediments of Lake Victoria in Jinja, Uganda, exhibit varying levels of naturally occurring radionuclides influenced by farming practices, the overall radiation exposure remains within safe limits. Continuous monitoring and regulatory measures are essential to maintain these safety levels and mitigate potential risks from increasing agricultural activities.

Activity Concentration of Natural Radionuclides in Surface Sediments of Major River Watersheds in Korea and Assessment of Radiological Hazards

The assessment of potential radiation hazards in accumulated sediments in aquatic ecosystems is vital for the management and disposal of sediments. Furthermore, preemptive management of radionuclides in terrestrial ecosystems is critical for marine ecosystem conservation. We analyzed the activity concentrations of natural radionuclides (226Ra,232Th, 238U, and 40K) in the surface sediments of major river watersheds in Korea and evaluated the radiation hazards stemming from these activity concentrations. The mean activity concentrations of 226Ra and 238U were lower than the global average, whereas those of 232Th and 40K were higher. The mean values of radium equivalent activity, external hazard index, and internal hazard index calculated from these activity concentrations did not exceed the recommended maximum values. The mean values of absorbed gamma dose rate in air and annual outdoor effective dose rate (AEDRout) were higher than the global average by the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) but remarkably lower than the recommended and background values by the International Commission on Radiological Protection (ICRP) and the Korea Institute of Nuclear Safety (KINS). The contribution of 40K and 232Th to the AEDRout mean value was predominant. In conclusion, the surface sediments of major river watersheds in Korea are associated with negligible radiation hazards. These findings provide fundamental data for the management and treatment of sediments in terrestrial and marine ecosystems.

Transfer factors of naturally occurring radionuclides from soil-to-rice cultivated in Bangladesh and associated health implications

This study investigates the uptake of naturally occurring radionuclides (226Ra, 232Th, and 40K) from soil by rice plants in extensively cultivated regions in Bangladesh. It also evaluates the potential radiation risks associated with rice consumption by the Bangladeshi populace. High purity germanium (HPGe) gamma-ray spectrometry was employed to measure the concentrations of radionuclides in both soil and rice samples. For 40K, our results agree with the International Atomic Energy Agency's (IAEA) published value; however, the transfer factors (TF) for the other two radionuclides differ considerably. Despite the fact that the IAEA based its publication of TFs for 226Ra and 232Th on clay soil, the majority of the soil profile in the present study was silty clay with a little alkalinity. Moreover, the data obtained may have been impacted by the growing seasons, cultivation methods, and soil fertility. Additionally, the annual effective dose due to the ingestion of radioactivity resulting from rice consumption was evaluated and the results agree with UNSCEAR (United Nations Scientific Committee on the Effects of Atomic Radiation), 2000. With a few exceptions, the excess lifetime cancer risk (ELCR) values for 226Ra, 232Th, and 40K were below the globally average permissible level (1 × 10−3). In light of this, the current study indicates that consuming rice does not pose an immediate health risk to the general public. By studying TFs among various rice varieties and geographical areas, scientists can develop models to forecast the possible radiation exposure from rice consumption and pinpoint activities or areas that require additional attention.

Assessment of indoor radon concentration in the dwellings of the industrial areas of Kannur District, Kerala.

All organisms on the earth-crest are exposed to natural background radiation since the evolution of the earth, as many environmental matrices such as soil, air, water bodies, vegetation, etc., act as the sources of natural radioactivity. The present study deals with the evaluation of indoor concentration of 222Rn (radon) in different dwellings with various construction materials used for the roof and floor in the industrial sites of Kannur district, Kerala. A pinhole-based dosemeter coupled with LR-115 Solid State Nuclear Track Detector and Direct Radon Progeny Sensor (DRPS) were respectively used for the measurement of indoor radon concentration and equilibrium equivalent concentration of radon. The indoor radon concentrations were found to vary from 102.30 Bqm-3 to 184.75 Bqm-3 and the values were within the recommended limits provided by International Commission on Radiological Protection (ICRP). The annual effective doses and excess lifetime cancer risks were observed in the range of 2.58-4.66 mSvy-1 and 7.68×10-3-15.60×10-3, respectively, and both exceed the world average values recommended by United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) 2000. The study shows that, the houses with marble floors and concrete roofs have comparatively higher values of radon concentration, which indicates the significant contribution of construction materials to the enhanced radiation levels inside the dwellings.

Calculate the Rate of Natural Radioactivity in the Soil of Some Schools Using the NaI(Tl) Detector in the City of Hilla-Iraq

Activities and risk markers in 15-20 cm soil samples from Hilla City schools were thoroughly examined. This was made possible by the NaI(Tl) detector. The results indicated that the specific activity values for 238U from 2.244±0.06 Bqkg-1 to 23.637±0.60 Bqkg-1, with an average value of 11.70±0.39 Bqkg-1. Similar to 232Th, the average specific activity level was 8.53±0.31 Bqkg-1, ranging between 1.603±0.09 Bqkg-1 and 21.503±0.56 Bqkg-1. For 40K, its specific activity range was 222.96±2.72 to 441.824±2.78 Bqkg-1, with an average of 375.32±2.71 Bqkg-1. The average radiative forcing of the radium equivalent (Raeq) was calculated to be 52.80 Bqkg-1. The external risk index (Hex) was 0.14, and the internal risk index (Hin) was 0.17. The gamma risk index (Iγ) was determined to be 0.41. Also, the average outdoor absorbed dose level Dout is 26.35 nGyh-1, while the average indoor absorbed dose level Din is 50.54 nGyh-1. The average annual values of effective dose equivalents (internal and external) are 0.03 and 0.25 nGyh-1. The additional lifetime cancer risk ELCR(t) due to natural radioactivity in the models was 0.93x10-3. Note that the global average permissible nuclide concentration was 30, 32, and 420, and the danger index values were 1, 1, 6, 59, 84, 0.4, 0.07, and 1.45, respectively, based on the report of the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR). After carefully comparing the study results with permissible global averages, they fit well within the recommended range.

Spatial distribution of NORMs concentrations and assessing potential risk to inhabitants in western Chattogram, Bangladesh

ABSTRACT This study represents a pioneering endeavour in consolidating previous measurements of naturally occurring radioactive materials (NORMs) within the Chattogram division, Bangladesh. Employing a meticulous approach, data was overlaid onto a comprehensive grid map covering the entire Chattogram region, comprising 523 grids, each of 8.05 km x 8.05 km. The analysis revealed numerous areas where NORMs concentrations had not been previously measured. To bridge this gap, soil samples were collected from 56 previously unmeasured locations across Cumilla and Chandpur districts and analysed using high purity Germanium (HPGe) detector technology. Results indicated average activity concentrations of Ra-226, Th-232, and K-40 at 27.30 ± 5.41, 46.09 ± 7.88, and 362.50 ± 48.10 Bq.kg−1 respectively, with no detectable presence of Cs-137 or other anthropogenic radionuclides, affirming the region’s absence of fallout or accidental releases. Additionally, measured values for radiation hazard indices are well within acceptable limits set by United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR). Spatial distribution maps of radionuclide concentrations and absorbed dose rates were generated not only for the immediate study area but also for the entire Chattogram division, integrating previously collected data for the first time. These distribution maps, alongside the comprehensive findings of this study, establish a pivotal dataset for future research and regulatory efforts, providing invaluable insights into the region’s radiological landscape.

Comprehensive Analysis of Contaminants in Powdered Milk Samples Using an HPGe for γ Radiation.

Aims: This study aimed to assess the activity concentrations and cancer risk assessments of 232Th and 40K in powdered milk samples collected from various suppliers in Pakistan, considering the increasing concern about cancer risks associated with environmental radiological effects related to food consumption. Subjects and Methods: Specific activity concentrations were determined using a high-resolution, high-purity germanium γ-spectroscopy system. Results: The specific activity levels of 40K and 232Th in the analyzed powdered milk samples were found to be 230.86 and 6.87 Bq/kg, respectively, well within the safe limits recommended by the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR). The hazard index (0.074 Bq/kg) and radium equivalent (27.58 Bq/kg) were calculated as indicators of radiation hazard, along with absorbed dose (26.26 nGy/h), annual effective dose (0.13 nGy/h), and excess lifetime cancer risk (0.45). These parameters provide insights into the potential health risks associated with powdered milk consumption. Conclusions: The findings collectively affirm the radiological safety of the analyzed powdered milk samples, providing valuable insights into the potential health risks associated with their consumption.

Assessment of natural background radiation levels in Ranipokhari, Kathmandu, Nepal, following the 2015 earthquake and during reconstruction

Natural background radiation is present in the environment and its level can vary depending on the location, occurring radioactive elements in soil, water, and air. The measurement of natural background radiation in Ranipokhari, a historic pond in Kathmandu, is important as it is currently undergoing reconstruction after the 2015 earthquake. We used a Professional Digital Geiger Counter (GCA 07W) to measure the radiation dose at 50 different locations, 31 of which were on the outer corner of the pond and 19 were inside the pond. The minimum and maximum radiation exposure levels were found to be 49.80 μR/h and 147.48 μR/h, respectively, with an overall average exposure rate of (108.06 ± 3.47) μR/h. We observed that the count and exposure rates were higher on sunny days compared to rainy days. Hypothesis testing suggested that the average background exposure rate in Ranipokhari is higher than the world average external background radiation levels reported by the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR). Our study provides crucial information on the natural background radiation levels in Ranipokhari, which can assist in the safe reconstruction of this historic pond after the earthquake.

Evaluation of radioactivity concentration in farm fresh milk and concomitant dose to consumer

In this study, activity concentrations of natural radionuclides in 28 raw milk samples collected from different dairy farms in Dhaka city of Bangladesh were measured using a high-purity germanium (HPGe) detector for the first time. The activity concentration of 226Ra, 232Th, and 40K in the investigated fresh milk samples ranged from BDL (Below detection level) to 26 ± 1.6 Bq/kg, BDL to 11.7 ± 3.3 Bq/kg and 101 ± 17 to 384 ± 32 Bq/kg, respectively. No artificial radionuclides were found in the investigated samples. Present results show inline within the range of available data in the literature. Annual committed effective doses were estimated following the consumption characteristics of raw milk by city population, values are found within the limiting range recommended by international organizations due to consumption of foodstuffs. Additionally, real-time gamma-ray dose rate in the farms/sampling locations was found in the range of 0.12 ± 0.01–0.20 ± 0.01 μSv/h by using a digital gamma survey meter (Gamma Scout) and the calculated maximum annual effective dose due to outdoor absorbed dose was found to be 0.25 mSv/y, which shows lower than the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) recommended limit of 2.4 mSv/y. This study indicates that the concentration of radionuclides in the farm fresh milk of Dhaka city does not pose any unwanted risk to public health, and it is safe to consume by both children and adults with the current intake level.

Radon exhalation and health hazard assessment for various ceramic tiles used in Bangladesh

Objective: Among various building materials, tiles are the most used decorative materials used worldwide. For the safe use of tiles at home and workplace it is required to select them properly based on radiation dose due to radon and gamma emission.
 Experiments: Among various tiles available in the market, 25 different types of tiles were collected for this experiment. Collected tiles are then ground and stored in sealed cans for secular equilibrium. To measure gamma activity due to the radionuclides 226Ra, 232Th, 40K, High Purity Germanium (HPGe) detector was used. To store radon gas emitting from tiles, a big box was used. The activity concentration was then measured by a radon detector (RadonEye) by placing it inside the box.
 Results and discussion: It was observed that 226Ra, 232Th, 40K activity varies from 45 – 89 Bq/Kg, 77 – 110 Bq/Kg, and 321 – 694 Bq/Kg. The radium equivalent activity varies from 198.32 – 280.46 Bq/Kg, less than the recommended value of 370 Bq/Kg set by UNSCEAR (United Nations Scientific Committee on the Effects of Atomic Radiation). The activity concentration of radon varies from 31 – 71 Bq/m3. This is lower than the 300 Bq/m3 recommended by ICRP (International Commission on Radiological Protection). The radon exhalation rate varies from 0.179 – 0.409 Bqm−2h−1. To assess radiological hazards associated with the tiles samples air absorbed dose rate, internal and external hazard index, gamma index, annual indoor and outdoor effective dose rate, and dose due to radon were also calculated.
 Conclusion: Though the estimated values for external and internal hazards are below the recommended values, they may be safe for adults. As children have thinner skin and breathe more air due to high breathing frequency, they may receive more radiation than adults. Moreover, they are at a greater risk because of their developing bodies and long life expectancy post-exposure.

Environmental radioactivity around a mining site and its impact on the populace within specified distances from the site in southwest Nigeria

In this study, we quantify specific activity of 238U, 232Th, and 40K, from soils, water, and vegetables around limestone mining sites because of the dense urban settlement with high agricultural activities around the area. Annual effective dose (AED) was evaluated and used to estimate radiological hazard impact. Mean values of internal radiation hazard index (Hin) for soils, water, and vegetation are calculated and compared with those from literatures. The estimated mean excess lifetime cancer risk (ELCR) was obtained, too. The values of ELCR are under the world average value as recommended by United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) one of the world regulatory bodies. For this reason, health related issues may occur at long time of living in this environment.

ИТОГИ 70-й СЕССИИ НАУЧНОГО КОМИТЕТА ПО ДЕЙСТВИЮ АТОМНОЙ РАДИАЦИИ (НКДАР) ООН (Вена, 19–23 июня 2023 г.)

The paper dwells upon the key outcomes of the 70-th Session of the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) which took place during 19-23 June 2023. Experts from 30 UNSCEAR Member-states as well as the representatives of international organizations participated in the work of the Session. Within the framework of the meetings of the working group and subgroups the documents on the following projects were discussed: R.757 “Second primary cancer after radiotherapy”, R.758 “Epidemiological studies of radiation and cancer”, R.759 “Evaluation of public exposures to ionizing radiation from natural and other sources”, R.760 “Evaluation of diseases of the circulatory system from radiation exposure” and R.761 “Nervous system effects of ionizing radiation”. The Committee also discussed interim reports: UNSCEAR/70/7 “Implementation of the Strategy to improve collection, analysis and dissemination of data on radiation exposure (including consideration of the Committee’s ad hoc working group on sources and exposure)”, UNSCEAR/70/8 “Implementation of the Committee’s Future Programme of Work and proposals for 2025‒2029 period (including consideration of the Committee’s ad hoc working group on effects and mechanisms)”, working materials for this document “Terms used by the United Nations Scientific Committee on the Effects of Atomic Radiation”, UNSCEAR/70/9 “Implementation of public information and outreach strategy for 2020–2024” and Report to the UN General Assembly.

Simultaneous measurements of radon, thoron and thoron progeny and induced cancer risk assessment in Djeno, Pointe-Noire, Republic of Congo.

In this study, the activity concentrations of radon (222Rn), thoron (220Rn) and thoron progeny were measured simultaneously in Djeno (Pointe-Noire, Republic of Congo) using RADUET detectors to evaluate the air quality and the radiological risks due to the inhalation of these radionuclides. Activity concentrations of radon progeny were calculated from those of radon. Indoor radon, thoron and progenies followed a lognormal distribution ranging between 20 and 40, 6 and 62, 8 and 17.6 and 0.4 and 19.6Bqm-3 for radon, thoron, radon progeny and thoron progeny, respectively. Mean values for radon were lower than the worldwide values estimated by the United Nation Scientific Committee on the Effects of Atomic Radiation (UNSCEAR), which are 40Bqm-3 (arithmetic mean) and 45Bqm-3 (geometric mean). Radon concentrations in the dwellings under study were below the World Health Organization and the International Commission on Radiological Protection recommended reference levels, which are, respectively, 100 and 300Bqm-3. The mean concentration of thoron was twice the world average value of 10Bqm-3 estimated by UNSCEAR. Thoron progeny mean concentration was sharply greater than the typical value (0.3Bqm-3) for indoor atmosphere provided by UNSCEAR. Annual effective dose ranges were 0.40-0.87mSv (arithmetic mean, 0.57±0.11mSv) for radon and 0.10-4.14mSv (arithmetic mean, 0.55±0.77mSv) for thoron. The mean value for radon was lower than the value (1.15mSv) estimated by UNSCEAR, while the mean value for thoron was five times higher than the UNSCEAR value (0.10mSv). The study showed that the use of the typical equilibrium factor value given by UNSCEAR to compute effective dose led to an error above 80%. Finally, the results of this study showed that the excess relative risk of radon-induced cancer was low, below 2% for the population under 55y. The results presented in the present study prove that the population of Djeno is exposed to a relatively low potential risk of radon- and thoron-induced cancer.

A Comprehensive Radiological Survey of Groundwater Resources in Artisanal Mining Communities in the Eastern Region of Ghana: Water Quality vs. Mining Activities

In recent times, groundwater has emerged as an alternative drinking water source for populations in Ghana’s gold mining communities due to high pollution levels in surface water resources caused by artisanal miners. This study presents the findings on different radioactivity levels in groundwater, their sources, the characteristics of aquifers in the study area, and the impact of radionuclides on human health as a factor of water quality. The mean activity concentrations of radionuclides in groundwater samples were 0.1 ± 0.04 Bq/L for Ra-226, 0.36 ± 0.05 Bq/L for Ra-228, and 1.41 ± 0.10 Bq/L for K-40. The activity concentration of 228Ra exceeded the World Health Organization (WHO) guideline level of 0.1 Bq/L. The elevated levels of Ra-228 in groundwater were found to be of natural origin, emanating from the aquifer rocks in the study area. Groundwater resources near mining zones showed higher radioactivity levels. The corresponding committed effective dose from consuming such groundwater was estimated to be higher than the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) recommended value of 0.3 mSv/y for children and infants, indicating potential health risks.

Environmental radioactivity, radiological hazards, and trace elements assessment of nearshore sediment in the Bay of Bengal

The current study focuses on the environmental radioactivity and multi-risk assessment of nearshore sediment as a source of marine pollution along the Bay of Bengal. The study examines the distribution of primordial radionuclide concentrations using a thallium-activated sodium iodide (NaI(Tl)) detector-based gamma-ray spectrometer and Potentially Toxic Elements (PTE) through atomic adsorption analysis. The data also were used to characterize ecological threats, radiological risks, and the geospatial distribution of toxic compounds in nearshore sediment as a proxy for marine pollution. The active concentration of primordial radionuclides such as uranium-238 (238U), thorium-232 (232Th), and potassium-40 (40K) was found in the range from ≤ 3 to 68 (11.4), ≤ 9.5 to 142.7 (41.2), and 85.2 to 603.4 (362) Bq/kg, and the results show that the average radioactive concentration of the average radionuclides was less than suggested by the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) ranges. Potentially toxic elements iron (Fe), chromium (Cr), nickel (Ni), lead (Pb), and zinc (Zn) were higher in deeper water depths. The current study reveals that mud distribution primarily controls such elements. A decreasing order has been seen as follows by the ecological risk index of individual elements: copper (Cu) > lead (Pb) > nickel (Ni) > chromium (Cr) > zinc (Zn). The significant Pb, Cu, and Zn concentrations indicated high pollution at most stations, possibly resulting from regional and terrestrial sources such as industrial activity, urban drainage, manufacturing, and farming. The migration of contaminated soil from the industrial and transportation sectors may be the source of the increased levels of hazardous elements and naturally occurring radionuclides in the sediment transported into the coastal ecosystems of Bay of Bengal.

Ingestion exposure of public to natural radionuclides and committed effective dose and cancer risk through tuber crops cultivated in Ebonyi State, Nigeria.

Internal exposure of public to radiation arising from ingestion of natural radionuclides in tuber crops of Ebonyi State origin was investigated in this study. Committed effective doses and lifetime cancer risk of 40K, 226Ra, and 232Th in cassava, cocoyam, water yam, and white yam were calculated. The average activity concentrations of 40K, 226Ra, and 232Th determined by gamma spectrometric Na (TI) detector were, respectively, 199.15 ± 23.51, 77.57 ± 7.98, and 118.20 ± 10.72 Bq/kg in cassava; 146.62 ± 40.69, 43.42 ± 7.63, and 75.61 ± 2.89 Bq/kg in cocoyam; 162.81 ± 20.43, 63.17 ± 11.36, and 81.50 ± 10.27 Bq/kg in water yam; and 184.50 ± 20.22, 80.23 ± 10.93, and 116.29 ± 5.93 Bq/kg in white yam. The total committed effective dose via ingestion aligned in this orderof cassava (7.05 mSv/year) > white yam (4.38 mSv/year) > water yam (0.42 mSv/year) > cocoyam (0.21 mSv/year) with overall average dose of 3.12 mSv/year. The values of dose were higher than world average of 0.29 mSv/year given by United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR). The lifetime cancer risk values were above tolerance level of >10-4 prescribed by United States Environmental Protection Agency (USEPA), suggesting probable evolvement of radiogenic cancer morbidity. The data presented in this study contributes to baseline information on radiological characteristics of tuber crops in Ebonyi, which would be valuable to WHO/FAO food safety policy in Nigeria and rest of the world.