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Exposure to ionizing radiation inside houses, especially radionuclides of radon and its progeny, poses serious health risks that can be exacerbated when inhaled as a result of interaction with human lung tissue. Also, air ionization is mainly due to these radionuclides. Therefore, accurate measurements of radon activity concentrations and its short-lived progeny are required to assess dose and environmental pollution and estimate ionization rates in indoor environments. For this purpose, we employed a previously tested and approved reliable method, following the three-count procedure. This method is based on airborne radon progeny sampling on polycarbonate membrane filters and alpha counting using a passive α-dosimetry technique with CR-39 detectors. The method also relies on a PC-based software we developed for solving mathematical equations and calculating all the necessary physical quantities. In this study, the concentrations of radon and individual short-lived radon progeny were measured in 20 houses in Sana'a, Yemen. Measurement conditions and meteorological variables were considered. The average activity concentrations of 222Rn, Equilibrium-Equivalent Concentration (EEC), 218Po, 214 Pb, and 214Po were 73.1 ± 6.0, 29.2 ± 2.4, 44.4 ± 3.6, 30.5 ± 2.5, and 23.2 ± 1.9 Bq.m-3, respectively. The calculated average unattached fractions f1(218Po), f2(214 Pb), and fp were found to be 0.24, 0.04, and 0.07 % respectively. The annual average values of ion-pair production rate caused by 222Rn and their progeny and air ion concentration, were 27.25 ions.cm-3s-1 and 1829 ions.cm-3 respectively. The annual effective dose was estimated to be 1.93 ± 0.16 mSv.y-1, well lower than the recommended 10 mSv.y-1.

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In the framework of the EMPIR research project Metrology for Radon, a facility was devised that provides stable and traceable atmospheres for the realization of radon activity concentration at a high metrological level. The facility is used to calibrate and test devices for measuring radon in the air. It enables precise long-term exposures in the range between 100 Bq/m3 and 1000 Bq/m3. The radon activity concentrations are realized with uncertainties of about 1.0 % (k = 1).

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This study evaluates the radiological risk associated with the consumption of infant powdered milk in Albania. Infant powdered milk is the basic foodstuff for their growth and development in many countries around the world. The activity concentration of radionuclides (40K, 226Ra, 232Th and 137Cs) was measured in fourteen types by using the gamma-ray technique. The results indicated that the activity concentration of 40K, 226Ra and 232Th were detected in all selected samples, whereas 137Cs were not detected in most of them. The activity concentration of 40K, 226Ra and 232Th varies from 92.83 ± 4.32 to 400.53 ± 17.00 Bq kg-1, 0.80 ± 0.15 to 4.91 ± 0.28 Bq kg-1 and 0.19 ± 0.02 to 1.89 ± 0.14 Bq kg-1, respectively. The highest value for 137Cs was found to be 0.36 ± 0.03 Bq kg-1. The average values of Annual Effective Dose (AED) due to consumption of powdered milk were found to be 664.54 ± 31.11 µSv y-1 for infants ≤1 year and 138.53 ± 5.40 µSv y-1 for infants 1-2 years. The values of dose in this study were lower than the recommended limit of 1 mSv y-1 set by WHO/FAO and ICRP for all ages. Therefore, brands of powdered milk are safe, so, these can be normally consumed by infants in Albania.

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Transfer of natural radionuclides from soil to water spinach (Ipomoea aquatica Forssk) in Hanoi, Vietnam have been investigated using a low background gamma spectrometer with an HPGe detector (Model-GC5019). Twenty pairs of soil and water spinach samples in two environmental conditions, i.e., flooded and unflooded, were collected for measuring the activity concentrations and determining the soil-to-plant transfer factors (TFs) of natural radionuclides. For water spinach, stems and leaves were collected as the main parts for human consumption and livestock food. The TF of 40K is within the range of 0.32-2.49, which is greater than that of 228Ra (0.01-0.17) and 226Ra (0.01-0.13). The geometric means (geometric standard deviations) of the TFs are 1.17(1.89), 0.05(2.41) and 0.04(1.88) for flooded sites, and 0.89(1.73), 0.03(2.12) and 0.03(1.82) for unflooded sites, respectively. Comparing between the flooded and unflooded sites, the TFs are all greater at the flooded sites.

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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.

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The radiation dose of workers in underground uranium mines mainly comes from radon and radon progeny. To ensure a healthy and safe work environment, it is necessary and urgent to optimize the design of ventilation systems. As such, based on the simplified radon diffusion-advection migration model of the rocks, this paper proposes 1) two methods for determining the radon exhalation rate modified by pressure drop, 2) three methods for calculating radon activity concentration of single-branch, and 3) the novel adjustment algorithm and solving procedures for calculating and adjusting the radon activity concentration in ventilation networks by modifying the radon exhalation rate, demonstrated on a specific ventilation network in a simulated underground uranium mine with calculation and analysis via MATLAB. The results show that 1) the radon exhalation rate of different branches can be modified by their pressure drop, and 2) the proposed method can be used to reveal the influences of different ventilation methods and fan pressures on the radon activity concentration in the ventilation network and the radon release rate to the atmosphere.

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This comprehensive study examines the concentration of natural radionuclides in bricks from the Terai region of the Koshi province, aiming to assess the radioactivity levels and associated radiological hazards, ultimately quantifying the dose limit. The average concentrations of 226Ra, 232Th, and 40K were 27.1 ± 5.7, 42.6 ± 9.8, and 601.5 ± 93.8 Bq/kg, with their respective contributions to total activity being 20.18 %, 45.35 %, 34.48 %,. Despite this, their concentration distribution followed the pattern 40K > 232Th > 226Ra. The elevated presence of 40K in the bricks is attributed to the use of phosphate fertilizers in the soil to enhance crop productivity. Notably, the calculated values of radiological hazard parameters, including radium equivalent activity, absorbed gamma dose, and effective dose, are well below the recommended safety thresholds. Consequently, this study suggests that bricks, when used in substantial quantities, pose no significant radiological risks and are considered safe for use as a building material. The extension of such investigations nationwide is recommended to assess the overall radioactivity levels and establish dose limits.

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ABSTRACTEnvironmental and health risks posed by radionuclides in quarry pit soils are of great concern in environmental health monitoring. The current investigation was aimed at determining the natural radionuclide activity concentration (in Bq kg-1) of the understudied quarry pit granules used as construction materials. The collection and preparation of pit soil samples from Abeokuta quarry sites were done using standard methods, analysis of radiological parameters was carried out using hyperpure germanium (HPGe) spectrometer. Specific activity concentrations of 226Ra, 232Th, and 40K were measured. The values obtained were greater than the world weighted average of 35, 30, and 400 Bq kg-1 for 226Ra, 232Th, and 40K, respectively. The absorbed dose, the annual effective dose, and the radium equivalent were calculated and demonstrated significant values. The radionuclide content of the samples is relatively high and the use of pit soils as a building material, therefore, raises radiological concerns for dwellers in this area and requires periodic monitoring and undergoing a radiation protection program.

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Introduction: All building materials of natural origin contain some amounts of primordial radionuclides, 40K, 232Th, and 238U, as well as other radionuclides in the decay series of 232Th and 238U. Purpose: The use of tiles to beautify walls and floors in dwellings has become popular worldwide and in Nigeria in particular. However, not much has been done in assessing the impact of the use of floor and wall tiles on the radiation exposure of dwellers. In this study, radioisotopes of natural origin (226Ra, 232Th, and 40K) in selected ceramic tiles often used in Ibadan Southwest Nigeria were estimated and the associated radiological parameters evaluated. Methodology: Forty-five samples of different types of floor and wall tiles were obtained from local markets within the study area. Each of the 45 samples was pulverized and sealed in an airtight sample container for 4 weeks before analysis using a sodium iodide-based gamma-ray spectrometer. Results: The average values of 226Ra, 232Th, and 40K obtained were 44.28 ± 0.56, 84.71 ± 0.60, and 830.44 ± 0.63 Bqkg-1, respectively, which shows that they are greater than the corresponding estimated worldwide average concentration. Again, the estimated average values obtained for the radiological hazard parameters for equivalent activity due to radium and representative gamma-ray level index were found to be lower than the world averages. Similarly, the absorbed dose rates due to gamma-ray emission were found to be higher than the world common values. Conclusion: This study indicates that the use of these tiles will not be posing potential radiological risk if used in dwellings. However, construction works that requires the use of these tiles must be designed in such a way that the emission of dangerous radiation will not be a threat to the occupants.

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According to reports, exposure to high concentrations of naturally occurring radioactive substances like Uranium-238, Thorium-232, and Potassium-40 poses serious health concerns. This review study aims to report the concentrations of radionuclides in various South African soil and their equivalent risk assessments, which have been sparingly reported. For South Africa, most radionuclide concentrations above the permissible limits of 33, 45, and 420 Bq.kg-1 for 238U, 232Th, and 40K, respectively, have been found in some soil samples taken near industrialization activities, including mining and oil exploration and production. Thus, the amount of radionuclides is a good indicator of the kind of soil, the local geology, and the mineral make-up of the parent rocks. The increases in radiation exposure to people and the environment have been reported to cause various radiological health hazards. Thus, this review study can be used as a data source to track probable radioactive contamination from soils found in South Africa.

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Assessment of activity levels of radionuclides that exist in soil, granite, and charnockite rock samples is very crucial because it exhibits an enhanced elemental concentration of uranium (U) and thorium (Th) contributing higher natural background activity than usual in the environment and it may cause health risk to human health through the external and internal exposure. This study determined the radioactivity levels of 238U, 232Th, and 40K radionuclides in soil, granite, and charnockite rock samples collected from selected fields in Ekiti State, Nigeria using Caesium iodide CsI(Tl) scintillation gamma spectrometer. It also evaluated indices of the radiological parameters consisting of radium equivalent activity (Raeq), absorbed dose rate (DR), annual effective dose equivalent (AEDE), internal hazard index (Hin), and excess lifetime cancer risk (ELCR). The calculated average activity concentrations of 238U, 232Th, and 40K are 30.40 ± 0.71 Bq kg-1, 3.31 ± 0.05 Bq kg-1, and 222.25 ± 14.72 Bq kg-1, respectively, which were lower than their respective world average values. Comparatively, potassium concentrations in these collected samples have a higher value than concentrations of uranium and thorium (40K > 238U > 232Th). All the evaluated values of the radiological parameters (except DR) of the appraised radionuclides were below the global permissible limits. The granite rocks, charnockite rocks, and soils from Ekiti State in Nigeria do not pose any hazardous risk to humans, but continued monitoring is necessary when these materials are used as building materials, which cause long-term radiation exposure.

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Cassava holds a vital position as a staple food in Nigeria, forming a significant portion of the daily diet for the population. Unfortunately, food intake can serve as a pathway for radiological contamination in humans and animals. In this study conducted in an old coal mining area in Enugu State, Nigeria, cassava samples from the area were analyzed using gamma ray spectroscopy. The results revealed significant mean activity concentrations of the radionuclides 40K, 226Ra, and 232Th in camp 1, camp 2, and Pottery areas. The activity concentration ranged from 193.68 to 300.92 Bq/kg for 40 K, 23.03 to 37.24 Bq/kg for 226Ra, and 135.33 to 158.43 Bq/kg for 232Th, respectively. Of concern is the total mean annual effective dose resulting from exposure to these 3 observed radionuclides that was calculated to be 2.03 mSv/yr. This value exceeds the recommended limit of 1 mSv/yr, indicating potential health risks associated with the radiological contamination from cassava consumption in this region. In summary, the study shows that cassava samples from the investigated area exhibited elevated levels of radiotoxicity, raising concerns about the safety of consuming cassava from this region as a food source.

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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 order of 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.

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This research presents the levels and distribution of 210Po in different sediments of the northeastern coast of the Mediterranean Sea. The 210Po activity concentrations were measured using an alpha spectroscopy system. The activity concentrations of 210Po in the sediment samples were in the range between 20.5 ± 0.7 and 92.8 ± 1.6 Bq kg-1 dw with an average of 48.2 ± 1.4 Bq kg-1 dw. The microorganism-enriched sampling sites (bedrock sites) indicated low 210Po concentration than sandy coastal sites. As a result of these measurements, the RESidual RADioactivity (RESRAD) biota code was applied to calculate the tissue concentration rate (CR), internal dose rate, external dose rate, and total dose rate of the exposed tissues. The total dose rates of aquatic animals were found higher than that of riparian animals. The 210Po sediment resource doses to aquatic and riparian animals were found less than the dose level recommended by International Commission on Radiological Protection (ICRP).

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A radiological baseline survey was conducted using a calculation analysis to assess the 226Ra, 232Th, 40K, and 137Cs distribution in beach sand samples collected from the coastal areas of the Mediterranean Sea. An analysis of the activity concentration of selected radionuclides was conducted. No evidence of recent migration of radiocaesium was found through precipitation, as well as indirect pathways, such as ocean runoff. The activity concentration of 226Ra, 232Th, 40K and 137Cs in beach sands ranged from 12 ± 1 to 37 ± 4 Bq kg- 1 (mean of 26 ± 3 Bq kg- 1); 18 ± 2 to 71 ± 8 Bq kg- 1 (mean of 40 ± 5 Bq kg- 1); 411 ± 10 to 720 ± 16 Bq kg- 1 (mean of 572 ± 12 Bq kg- 1); and 0.8 ± 0.1 to 3.1 ± 0.6 Bq kg- 1 (mean of 1.9 ± 0.3 Bq kg- 1), respectively. The radiological risk assessment showed that in all cases the values were lower than those that endanger life and safe work.

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A new-designed measurement device for radon and thoron activity concentration is developed based on gas direct measurement to support their in-situ calibration. It consists of a 2000 mm2 Passivated Implanted Planar Silicon (PIPS) detector, a Multi-Channel Analyzer (MCA), a Micro Controller Unit (MCU), and a small electrostatic chamber with a volume of nearly 23 ml. The device records those alpha particles emitted from radon and thoron gas, and the detection efficiency and the crosstalk factor of 218Po/216Po are determined by Monte Carlo simulation. Measurement results have been compared with AlphaGUARD DF2000 in pure radon and thoron environments, respectively. Results show that the measurement results of the devices and the reference monitor agree well with each other, with an average relative deviation of 0.48% for radon gas from about 3300 Bq/m3 to 38 kBq/m3 and -3.25% for thoron gas from about 25 kBq/m3 to 70 kBq/m3. Uncertainty assessment has also been done, and a relative system uncertainty of radon is about 6.8%, while that of thoron is nearly 7.3%.

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Technetium-99m generators employing a technetium-selective stationary phase are a chromatographic instrument developed for use with 99Mo having low specific activity (LSA); particularly, 99Mo produced by electron accelerators. This paper presents a mathematical description of technetium-selective chromatographic (TSC) 99mTc separation and analyzes its compatibility with LSA 99Mo. We developed a theoretical formula for TSC 99mTc separation by discretizing its pertechnetate selectivity, and validated it using an electron linear accelerator and activated carbon-based TSC (AC-TSC) 99mTc generators. We confirmed that the activity concentration of 99mTc obtained from a TSC 99mTc generator can be calculated directly from its input 99Mo activity regardless of the 99Mo specific activity. The formula corroborates that TSC 99mTc separation is compatible with LSA 99Mo, and has a practical application in estimating the number of TSC 99mTc generators required for 99mTc demand of interest.

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The authors characterize the use of 222Rn as an effective tracer of natural ventilation of an underground site where air circulates within a whole system of workings and ventilation intensity (the number of air exchanges in the space) is determined by atmospheric factors. A radon-related database containing results of measurements conducted at various intervals and at different stages of site accessibility was compiled. During 8 months of the calendar year 222Rn activity concentration exceeds the mean annual reference value established by Polish law (300 Bq/m3). These months correspond to periods with low intensity of natural ventilation of the workings and reduced efficiency of air exchange between the site and the atmosphere. They occur in autumn - in the second half of September, in October and November, and in May in spring, and persist for 7 to even 14 days. During these periods, the time spent inside the facility which is considered safe in terms of radiation protection is limited to an average of 6-8 h a day, i.e. from 6 a.m. to 6 p.m. in October, from 11 a.m. to 6 p.m. in November and from 11 a.m. to 5 p.m. in May. The length of a safe stay in the facility is determined by atmospheric factors, mainly the air and ground temperature. The concentrations of other gases in the atmosphere inside the facility comply with Polish mining regulations.

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The manufacture of Portland cement entails high energy and environmental costs, and various solutions have been implemented in recent years to mitigate this negative impact. These solutions include improvements in the manufacture of cement clinker or the use of supplementary cementitious materials (SCMs), such as fly ash (FA) or slag as a replacement for a portion of the clinker in cement. The incorporation of these SCMs in cement may increase its radiological content as they are naturally occurring radioactive materials (NORMs). The Activity Concentration Index (ACI) is a screening tool established in the European EURATOM Directive 2013/59 to determine the radiation protection suitability of a final construction material. The ACI is determined by the activity concentrations of 226Ra, 232Th and 40K, usually determined by gamma spectrometry. The methodology of gamma spectrometry is accurate and appropriate, but this technique is not available in all laboratories. For this reason, and taking into account that there is a relationship between the chemical and radiological composition of these building materials, a new approach is proposed to determine the radiological content of these materials from a chemical analysis such as X-ray fluorescence (XRF). In this paper, principal component analysis (PCA) is used to establish the relationships between the chemical composition and radiological content of cements, FAs, and slags of different natures. Through PCA it was possible to group the cements based on two variables: CaO content and Fe2O3-Al2O3-TiO2 content. A lower correlation was observed for the FAs and slags, as the sample scores were centered around the origin of the coordinates and showed greater dispersion than the cements. The clusters obtained in the HJ-Biplots allowed the determination, using multiple regression, of models relating the activity concentration of 226Ra, 232Th (212Pb), and 40K to the oxide percentages obtained for the three matrices studied. The models were validated using five cements, one FA and one slag with relative percentage deviations (RSD(%)) equal to or less than 30% for 89% of the activity concentrations and 100% of the ACI determined.

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This work studied the spatial pattern of four natural radionuclides (226Ra, 228Ra, 228Th and 40K) as well as one artificial one (137Cs) in soils in the Chimborazo province (Ecuador), which belongs to the North Andes of South America. Soil samples were collected considering the Ecuador geological map. Statistical analyses showed that activity concentrations of 226Ra, 228Ra, 228Th do not exceed the worldwide average, while one geological unit exceeds the worldwide average for 40K. These high activity concentrations are attributed to radionuclide accumulation in plutonic and metamorphic rocks and also in ash resulting from eruptions of the Sangay volcano. The inverse distance weighted interpolation method was used to develop corresponding radioactivity maps where the highest activity concentrations are in the central-east of the studied area. In addition, a distribution pattern of 226Ra and 40K is observed in the geologies influenced by the presence of Chimborazo, Igualata, Tungurahua and Altar volcanoes. Spearman's nonparametric test shows positive correlations suggesting the presence of very homogeneous lithologies and that volcanic activities can influence the distribution of radionuclides in our environment. In seven of the samples, 137Cs was detected.

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