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Purpose: Since 2014, an educational activity on radiation and health in northern Japan has been carried out by young scientists, the so-called 'Educational Symposium on Radiation and Health (ESRAH)'. Close cooperation has been continued in preparing for any possible emergency response to radiation accidents because several facilities, e.g., the Tomari Nuclear Power Plant in Hokkaido and the Low-Level Radioactive Waste Disposal Facility in Aomori prefecture. The ESRAH meeting has provided informational exchange and discussion forum on a broad range of subjects in various. In 2023, the 10th Memorial ESRAH meeting took place to boost scientific understanding and multidisciplinary collaborations for young scientists. Herein, we report on the ESRAH2023 symposium and analyze the research categories of young scientists from the past 10-year presentations. Conclusions: To date, the ESRAH meeting has successfully provided a chance for multi-disciplinary research, which accounted for 27% of the total despite the COVID-19 pandemic. We found that the fraction of multi-disciplinary research in 2023 was the highest during 10-year ESRAH meetings. Meanwhile, amongst the research categories, physics, chemistry, and pharmacological studies were indicated to be less for young scientists. It is desired that further collaboration between physics, chemistry, and pharmacology in addition to the current fields would not only clarify radiation effects on the human body but also promote emergency medical care for radiation exposure in the future. [ABSTRACT FROM AUTHOR]

This study evaluates the concentrations of trace elements (TEs) in soils from the rutile deposit area of Akonolinga, Cameroon, and analyzes the associated health risks. A total of 25 samples were analyzed using flame atomic absorption spectrometry (FAAS). The results show that TE concentrations follow the decreasing order Fe, Ti, Zr, Mn, Cr, V, Ba, Zn, Nb, Ni, Pb, Ga, Cu, Co, Y, Br, and Sn. Pollution indices and the Pearson correlation matrix reveal moderate correlations between Fe and several other TEs, indicating a common origin. Enrichment Factors show significant enrichment in Zr, Nb, and Ti, with notable enrichment in Cr and Co at certain sites. Although the Geo-Accumulation Index indicates no direct contamination and the overall ecological risk is low, the Contamination Factor reveals high levels for Cr, Nb, Ti, and Zr. The carcinogenic risk is moderate, while non-carcinogenic risks are high for children and considerable for adults. These research highlight the potential public health impacts in this mining region and provide essential baseline data for future environmental risk management. [ABSTRACT FROM AUTHOR]

Surface collection efficiency (SCE) of a cellulose membrane filter (CMF) and a cellulose-glass fiber filter used in environmental monitoring for alpha-emitting radionuclides from nuclear facilities and natural radioactivity sources was evaluated for particles in the size range of 0.03–0.1 μm at different levels of face velocity. The SCE of the CMF was higher than that of the cellulose-glass fiber filter, and only the membrane filter showed the dependence of SCE on the particle size at higher face velocity. The use of the CMF at higher face velocity in environmental radioactivity monitoring leads to measurements of the background alpha spectrum with more degradation under the changing particle size condition in the atmosphere. Consequently, that fact needs to be taken into account, along with the expected particle size distribution and concentration of the airborne radioactivity being sampled, when selecting a face velocity to achieve the best possible detection limit. [ABSTRACT FROM AUTHOR]

222Rn is recognized as a matter of international concern for human health risk. Because 220Rn as well as 222Rn coexist in the natural environment, thoron sometimes influences the experiment for radon measurement. It is important to measure radon and thoron separately to evaluate the risk of the exposure to 222Rn. As a discriminative measurement method for 222Rn and 220Rn, a simple technique with a single scintillation cell is well known. However, in recent years, the influence of atmospheric environment on the geometrical efficiency of the scintillation cell has not yet been investigated. In this study, environmental dependence of geometrical efficiency for the scintillation cell in 222Rn and 220Rn measurement was investigated using the Lucas type scintillation cell and Monte Carlo particle simulation. It was found that the influence of temperature and pressure on the geometrical efficiencies were larger than that of relative humidity. [ABSTRACT FROM AUTHOR]

The World Health Organization (WHO) recommends that countries adopt the reference level of 100 Bq m−3 for indoor radon gas. Adopting the reference level requires a preliminary assessment of the indoor radon concentration. In the preliminary investigation, a cut-off value is useful, which is a value for selecting samples that can be reliably determined to be below the reference level (in this paper, the WHO reference level) using a straightforward method. If the true value was the WHO reference level, then the cut-off value of the PicoRad collector for selecting samples was determined as 80 Bq m−3 through the analysis of the 95% prediction interval. [ABSTRACT FROM AUTHOR]

The National Metrology Institute of Japan plan to use an inner-through-type ionization chamber (IC) as a working standard to calibrate radon monitors. Novel methods to calibrate the IC were described, and the calibration factor, CF [Bq m −3 A−1], of the IC with its expanded uncertainty (k  = 2) was evaluated to be (2.0 ± 0.2) × 1016 Bq m−3 A−1 in the order of 10−13 A in the IC output current. In this study, the CFs, evaluated under sampling conditions between continuous gas flowing and stationary gas filled inside the IC, were in agreement within the uncertainty. [ABSTRACT FROM AUTHOR]

Passive radon monitors with CR-39s are widely used in major epidemiological surveys. However, the conventional CR-39 track density determining strategy makes it difficult to accurately estimate the concentration because of the heterogeneity of tracks on CR-39s. This study introduced a stochastic method, Latin hypercube sampling, to improve the track density determining strategy and provide the probability distribution of 222Rn concentration and equilibrium equivalent thoron concentration. The first 222Rn and 220Rn discriminated survey was conducted in Wuhan, China, in 2018 using RADUET® and deposition-based passive 220Rn progeny monitors and applying the stochastic method to the measurement. The results indicate that the stochastic method could decrease the effects of the track heterogeneity on the CR-39s and provide reliable results. The 220Rn progeny contributed more than 40% of the total inhalation dose in the survey, which cannot be ignored in urban family dwellings. [ABSTRACT FROM AUTHOR]

The deposition-based direct indoor 222Rn and 220Rn progeny measurement techniques are mostly affected by the indoor environmental conditions, such as the ventilation, concentration of condensation nuclei, and reactions with the structure and its furnishings. In this study, a theoretical model of a direct 222Rn and 220Rn progeny monitor based on allyl diglycol carbonate (ADC or CR-39) was established to analyse the factors that influence the detection process by using the parameter sensitivity analysis. The aerosol parameters contributed the highest to the variance, followed by the aerodynamic parameters. With respect to the result of the Spearman’s correlation analysis, the aerosol-related and the room-related parameters are positive, whereas the aerodynamic parameters – which affect the turbulence of indoor deposition – are negative. It means that both the attachment process and the deposition process of 222Rn and 220Rn progenies are important to the performance of the progeny monitor.

The exposure from radon, thoron, and thoron progeny was measured for 45 dwellings in high background radiation area in Takandeang, Indonesia with ambient dose equivalent rate ranging from 0.34 μSv h−1 to 1.90 μSv h−1. The measurement was taken using passive radon and thoron discriminative detector and thoron progeny detector. This measurement was taken from November 2018 to October 2019, and within one month the detector would be replaced with a new detector. The concentrations of radon, thoron, and thoron progeny were calculated as 42–490 Bq m−3, 20–618 Bq m−3, and 4–40 Bq m−3, respectively. The concentrations for outdoor were 49–435 Bq m−3, 23–457 Bq m−3, and 4–37 Bq m−3, respectively, and the annual effective dose was 9.8–28.6 mSv y−1. Based on the result of Spearman’s correlations analysis between the indoor radon and thoron concentrations and between the indoor thoron progeny and thoron concentrations, we suggest that exposure to thoron cannot be predicted from exposure to radon, and the equilibrium equivalent thoron concentration has a large uncertainty when it is estimated from thoron concentration assuming a single thoron equilibrium factor.

To assess public exposure to radon, thoron, and their progeny, measurements were conducted in 50 dwellings within the bauxite-rich area of Fongo-Tongo in western Cameroon. Passive integrating radon-thoron discriminative detectors (specifically RADUET) were employed for radon and thoron measurements. Additionally, concentrations of short-lived radon and thoron progeny were estimated using Direct Radon Progeny Sensors (DRPSs) and Direct Thoron Progeny Sensors (DTPSs) based on LR-115 detectors. The findings revealed indoor radon concentrations ranging from 31 to 123 Bq m−3 with a geometric mean (GM) of 62 Bq m−3, and indoor thoron concentrations ranging from 36 to 688 Bq m−3 with a GM of 242 Bq m−3. The Equilibrium Equivalent Radon Concentration (EERC) ranged from 3 to 86 Bq m−3 with a GM of 25 Bq m−3, while the Equilibrium Equivalent Thoron Concentration (EETC) ranged from 1.2 to 12.5 Bq m−3 with a GM of 7.6 Bq m−3. Notably, all dwellings recorded radon concentrations below 100 Bq m−3. Arithmetic means of radon and thoron equilibrium factors were calculated as 0.47 and 0.04, respectively. To assess annual effective doses from radon and thoron inhalation, equilibrium factors were used along with direct measurements of EERC and EETC. The differences observed in annual effective doses were 4.5% for radon and 42.5% for thoron. Furthermore, the contribution of thoron and its decay products to the annual effective dose from radon, thoron, and their progeny ranged from 12 to 94%, with an average contribution of 58%. Thus, this study found that the effective dose due to thoron inhalation in the study area exceeded that due to radon inhalation. It is concluded that, when evaluating radiation doses and health risks, it is crucial to consider both thoron and its progeny alongside radon and its progeny. This underscores the importance of considering direct measurements for accurately estimating radiation doses. [ABSTRACT FROM AUTHOR]

Radiation shielding materials have been researched using Pb and metal oxide particles, and composites of resin and barium sulfate (BaSO4) have been reported. In addition, multiwalled carbon nanotubes (MWCNTs) have often been used as a nanomaterial to improve the mechanical strength of resin–BaSO4 composites. The literature includes no examples of these two materials—BaSO4 and MWCNTs—being used at the interface of composites. We effectively modified the surface of BaSO4 by a simple process involving strong electrostatic interaction between positively charged barium and negatively charged functional groups on the MWCNT surface. The process is simple and can form large amounts of MWCNTs that coat BaSO4 surfaces. As a result, MWCNTs remained on the BaSO4 surface even after the MWCNT‐coated BaSO4 was washed with a solvent and subjected to melt mixing. The physical anchoring of MWCNTs onto the BaSO4 surface improved the interfacial adhesion and mechanical properties of the resultant composites. The originality of this research is that MWCNTs can be coated onto the surface by only electrostatic interaction without using a polymer adhesive. In addition, the x‐ray shielding performance of the MWCNT‐containing composites was the same as that of composites prepared without the MWCNTs. Highlights: MWCNTs were coated onto the surface of BaSO4 by electrostatic interaction.Interfacial adhesion of PS composites was improved by coating MWCNTs.The MWCNTs did not affect the x‐ray shielding performance. [ABSTRACT FROM AUTHOR]

Chiang Mai province of Thailand is known for having the highest natural background radiation in the country, as well as being recognized as one of the world's most polluted cities for air quality. This represents the major contributor to the development of lung cancer. This research aims to estimate the comprehensive dose of both internal and external exposure due to natural background radiation and related health perspectives in the highly polluted area of Chiang Mai. The average values of indoor radon and thoron concentrations in 99 houses over 6 months were 40.8 ± 22.6 and 17.8 ± 16.3 Bq/m3, respectively. These results exceed the worldwide value for indoor radon and thoron (40 and 10 Bq/m3), respectively. During burning season, the average values of indoor radon (56.7 ± 20 Bq/m3) and thoron (20.8 ± 20.4 Bq/m3) concentrations were higher than the world-wide averages. The radon concentration in drinking water (56 samples) varied from 0.1 to 91.9 Bq/L, with an average value of 9.1 ± 22.8 Bq/L. Most of the drinking water samples (87%) fell below the recommended maximum contamination limit of 11.1 Bq/L. The average values of natural radionuclide (226Ra, 232Th and 40K) in 48 soil samples were 47 ± 20.9, 77.9 ± 29.7 and 700.1 ± 233 Bq/kg, respectively. All values were higher than the worldwide average of 35, 30 and 400 Bq/kg, respectively. The average value of outdoor absorbed gamma dose rate (98 ± 32.5 nGy/h) exceeded the worldwide average of 59 nGy/h. Meanwhile, the average activity concentrations of 226Ra, 232Th and 40K in 25 plant food samples were 2.7 ± 0.1, 3.2 ± 1.6 and 1000.7 ± 1.9 Bq/kg, respectively. The 40K concentration was the most predominant in plant foods. The highest concentrations of 226Ra, 232Th and 40K were found in Chinese cabbage, celery and cilantro, respectively. The total annual effective dose for residents in the study area varied from 0.6 to 4.3 mSv, with an average value of 1.4 mSv. This indicates a significant long-term public health hazard due to natural background radiation and suggests a heightened radiation risk for the residents. The excess lifetime cancer risk value (5.4) associated with natural background radiation was found to be higher than the recommended value. Moreover, the number of lung cancer cases per year per million average of 25.2 per million persons per year was in the limit range 170–230 per million people. Overall, our results will be used for future decision making in the prevention of lung cancer risk associated with natural background radiation. [ABSTRACT FROM AUTHOR]

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 19.6 Bq m−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 40 Bq m−3 (arithmetic mean) and 45 Bq m−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 300 Bq m−3. The mean concentration of thoron was twice the world average value of 10 Bq m−3 estimated by UNSCEAR. Thoron progeny mean concentration was sharply greater than the typical value (0.3 Bq m−3) for indoor atmosphere provided by UNSCEAR. Annual effective dose ranges were 0.40–0.87 mSv (arithmetic mean, 0.57 ± 0.11 mSv) for radon and 0.10–4.14 mSv (arithmetic mean, 0.55 ± 0.77 mSv) for thoron. The mean value for radon was lower than the value (1.15 mSv) estimated by UNSCEAR, while the mean value for thoron was five times higher than the UNSCEAR value (0.10 mSv). 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 55 y. 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. [ABSTRACT FROM AUTHOR]