Total Annual Effective Dose Research Articles

Article title: Assessment of natural radioactivity (40K, 238U and 232Th) and radiological risk in building construction materials: the case of Benin hill granites

Continuous exposure to ionizing radiation can have harmful effects on human health. In this respect, a study was carried out in the Communes of Dassa-zoume and Glazoue to determine the levels of 40K, 238U and 232Th in granites and sand. The specific activities obtained made it possible to assess the possible radiological risks associated with the resident population. During sampling work in November 2022, twelve granite samples were taken from twelve quarries. In addition, a sand sample was collected in Cotonou for comparison. All samples were then sent to the INSTN-Madagascar laboratory for gamma-ray spectrometry analysis using a NaI(TI) detector. The results show that the average specific activities of 40K, 238U and 232Th in the granites are (1329 ± 128) Bq.kg-1, (44 ± 11) Bq.kg-1 and (129 ± 44) Bq.kg-1 respectively. Those in sand are (144 ± 8) Bq.kg-1, (30 ± 2) Bq.kg-1 and (56 ± 7) Bq.kg-1 respectively. The average equivalent radium activity is (330 ± 74) Bq.kg-1 versus (122 ± 10) Bq.kg-1 for sand. The mean gamma index for granite was (1.2 ± 0.3), compared with (0.43 ± 0.03) for sand. The average absorbed dose rate in air is (153.4 ± 9.4) nGy.h-1 versus (53.7 ± 5.1) nGy.h-1 for sand. For adults, for 80% building occupancy factor, the mean annual indoors and outdoors effective dose (E) inside a building are (0.75 ± 0.05) mSv.y-1 and (0.19 ± 0.01) mSv.y-1 versus (0.26 ± 0.05) mSv.y-1 and (0.07 ± 0.01) mSv.y-1 for sand. For 60% factor, the means are (0.56 ± 0.03) mSv.y-1 and (0.38 ± 0.02) mSv.y-1 versus (0.20 ± 0.01) and (0.13 ± 0.01) mSv.y-1 for sand. For the children, for a building occupancy factor of 80%, the average E are (0.86 ± 0.05) mSv.y-1 and (0.21 ± 0.01) mSv.y-1 versus (0.30 ± 0.01) mSv.y-1 and (0.08 ± 0.01) mSv.y-1 for sand respectively for indoors and outdoors. For infants, the E are (1.00 ± 0.06) mSv.y-1 and (0.25 ± 0.01) mSv.y-1 versus (0.35 ± 0.01) mSv.y-1 and (0.09 ± 0.01) mSv.y-1 for sand respectively for indoors and outdoors. For children, for a building occupancy factor of 60%, the average E are (0.64 ± 0.03) mSv.y-1 and (0.43 ± 0.02) mSv.y-1 versus (0.23 ± 0.01) mSv.y-1 and (0.15 ± 0.01) mSv.y-1 for sand respectively indoors and outdoors. For infants, for a building occupancy factor of 60%, the E are (0.75 ± 0.05) mSv.y-1 and (0.50 ± 0.02) mSv.y-1 versus (0.26 ± 0.01) mSv.y-1 and (0.18 ± 0.01) mSv.y-1 for sand respectively indoors and outdoors. For adults, the excess lifetime cancer risk at age 66 for a total annual effective dose induced by granite is (3.1 ± 0.01).10-3 versus (1.1 ± 0.01).10-3 for sand. For the children and infants, the average ELCR is (3.5 ± 0.01)E-3 and (4.1 ± 0.01)E-3 versus (1.2 ± 0.01)E-3 and (1.4 ± 0.01)E-3 for sand respectively. Statistical analysis of the data was performed with Python 3.11 and R 4.3.2 on the Spyder and studio interface. The p-value is < 0.001 compared with the UNSCEAR reference value for absorbed dose rate in air, effective dose and excess risk, which are 84 nGy.h-1, 0.48 mSv.y-1 and 0.29.10-3. This shows that the granites in the quarries studied present a radiological risk when used as building materials and need specific radiation protection measures for his users.

Assessment of annual effective doses from indoor radon and thoron in Doi Lo, Chiang Mai, Thailand.

This study aimed to determine the annual effective dose resulting from radon and thoron progeny inhalation. The levels of radon, thoron, and progeny were assessed in residences situated in the Doi Lo region of Chiang Mai, Thailand. Indoor radon and thoron concentrations were detected using passive discriminative detectors. Using a progeny deposition rate detector, this study evaluates radon and thoron progeny [equilibrium-equivalent radon concentration (EERC) for radon and equilibrium-equivalent thoron concentration (EETC) for thoron]. Data were collected from 44 dwellings between March and May 2020. The results found that indoor radon concentrations ranged from 17 to 118Bqm-3, while thoron concentrations ranged from 12 to 72Bqm-3. The radon progeny (EERC) ranged from 4 to 173Bqm-3, whereas thoron progeny (EETC) ranged from 1 to 15Bqm-3. The total annual effective dose received from radon and thoron progeny inhalation varied from 0.5 to 5mSv y-1.

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.

Dose assessment from exposure to uranium and radon in groundwater in Safi province, Morocco

ABSTRACT In this study we evaluate the uranium and radon concentrations in groundwater from the Province of Safi. The samples were collected from 58 wells across five communes and analyzed using the LR-115 type II detector. Results indicate that uranium concentrations ranged from the Limit of Detection (LLD) to 3.73 µg/l, with a mean of 0.72 µg/l, well below the World Health Organization’s safe limit of 30 µg/l. Radon levels varied from LLD to 2.39 Bq/l, with an average of 0.60 Bq/l, also below the United States Environmental Protection Agency’s limit of 11 Bq/l. The estimated total annual effective dose due to uranium and radon ranged from 3.47 to 18.84 µSv/y, with an average of 7.54 µSv/y, which is significantly lower than the European Commission’s recommended limit of 100 µSv/y. This investigation represents the first study of uranium and radon levels in groundwater in the Province of Safi, providing valuable data for future research and public health.

Total Radiological Dose and Safety Assessment of Workers in Radioactive Liquid Waste Storage Location in Al Tuwaitha Site

This study aims to determine the total effective dose (external and internal) in the radioactive liquid Waste Hall (WH) in the Radiochemistry Laboratories building (RCL) in Al- Tuwaitha site in order to estimate the radiation risk for workers in this place. The external effective dose was calculated by an indirect method using ThermoLuminescent Dosimeters (LiF: Mg, Ti (TLD-100)) by placing them in the waste hall for one month. The internal effective dose was estimated by collecting eight air samples (environmental samples) from different locations in WH using an air sampler pump (Sniffer) to collect air samples loaded with particles or dust which are deposited on cellulose filter papers (φ 125mm). This was done for two flow rates the lowest and the highest values of the air sampler pump of 5CFM and 20CFM, respectively.The filter papers were chemically treated using the digestion method. The radionuclides in these samples were measured using a gamma spectrometry system equipped with a high-purity germanium detector (HPGe), and the radioactivity concentration was measured using a gross alpha beta gamma system. The results showed 137Cs of low concentration was deposited on the filter paper. The total annual effective dose rate (external and internal) results showed that the highest in WH was (6358.97μSv/year) for the low probability scenario and (1589.74 μSv/year) for the realistic scenario.

Measurement of gross alpha radioactivity levels and estimation of annual effective dose in hazelnut kernels

Abstract The present study investigates gross alpha (GA) radioactivity levels in hazelnut kernels purchased from markets in Türkiye. 10 different hazelnut samples were crushed and made ready for counting. The alpha counts were obtained via ELSEC 7286 low level alpha counter with ZnS scintillator and EMI 6097B photomultiplier tube. The samples were placed in front of the detector to acquire the counts. All samples were counted isochronously. In addition to the GA activity measurement, total annual effective dose (AED) value for different age groups owing to ingestion was calculated for each sample. It was observed that the GA radioactivity levels in the samples were quite low, and total AED values were considerably lower than the WHO worldwide average AED value (290 μSv/year).

Assessment of naturally occurring radionuclides in surface soil and drinking water from western part of Yadgir district Karnataka, India.

Radionuclide activity of the selected radionuclides 238U, 232Th and 40K was measured in surface soil samples collected from 40 villages of the western part of Yadgir district of Karnataka. A 4″×4″ NaI (Tl) detector based on a gamma spectrometer is used for the estimation of radionuclides. The major type of soil in this region is sandy and red. The 222Rn activity concentrations in drinking water were determined by the Emanometry method. The 222Rn activity in ground water is found to vary from 1.73 to 155.6Bql-1. The total annual effective doses because of 222Rn inhalation and ingestion range from 4.72 to 424.84μSv y-1 with an average value of 108.8μSv y-1, respectively. Among the sampling stations, Shahapur and Shorapur soil samples show higher activity values than the Kembhavi and Hunasagi sampling stations soil samples.

Ambient gamma radiation level around Kaveri river basin, Karnataka state, India.

Studies on ambient gamma radiation in indoor and outdoor environment and their effect on human health have created interest among the researchers across the world. The present study represents the results of indoor and outdoor ambient gamma dose rates around the Kaveri river basin from Talakaveri (Madikeri district) to Mekedatu (Ramanagara district) by using portable Environmental Radiation Dosemeter. The annual effective dose in the present study area varies between 0.14mSv.y-1 and 0.58mSv.y-1 with an average value of 0.30mSv.y-1 for indoor radiation. The outdoor annual effective dose ranged between 0.01mSv.y-1 and 0.14mSv.y-1 with an average value of 0.06mSv.y-1. The total annual effective dose varies from 0.17 to 0.72mSv.y-1 with an average value of 0.36mSv.y-1. The calculated values of indoor and outdoor annual effective dose in the study area (are found to be lower than the world average values (1mSv.y-1 and 0.48mSv.y-1).

Radiological impact of hydrocarbon waste release on drinking water of ughievwen and udu communities, delta state Nigeria

Well water quality has been characterized with constant and continuous changes via the interaction of rock, soil and natural nano-filters which terminates at the aquiferous layer for clean well-water collection. The continuous exploration and production of crude oil has resulted significant increase of unwanted elements such as naturally occurring radionuclides in the water-bed which necessitates this study. The study determines the radionuclides based health impact or hazards associated with drinking water from crude oil exploration/production release in Ughievwen and Udu communities of Delta State, Nigeria. Sixty well water samples (three samples from each community) were collected and analyzed using sodium iodide (Nal (Tl)) detector. The obtained mean values of 238U, 232Th and 40K are 6.91 ± 1.62BqL−1, 4.39 ± 1.47 BqL−1 and 24.54 ± 1.59 BqL−1 respectively. The 238U, 232Th and 40K results showed that the measured values are higher than the world standard (UNSCEAR; WHO) and the control values The mean values of total annual effective dose of different age groups are: 11.08 mSvy−1, 2.54 mSvy−1, 1.93 mSvy−1, 2.52 mSvy−1, 7.03 mSvy−1 and 1.12 mSvy−1 respectively. While the mean committed effective dose of adult is 55.94 mSvy−1. The total annual effective dose, committed effective dose, cancer risks and hereditary effects are all lower than recommended limit (WHO; ICRP; USEPA) and reported scientific values except 11.08 mSvy−1 and 7.03 mSvy−1 that are higher than limit. It is evident from obtained results that the drinking water may not be radiologically safe for use by the public, which necessitates routine monitoring and caution to circumvent increase in radiation and the radiological of the studied communities’ drinking water. This is to avoid long term radiological risk arising from accumulation of such release in the studied communities.

Simultaneous indoor radon/thoron and in situ outdoor gamma dose measurements and estimation of annual effective dose in a tin mining area of Jos Plateau, Nigeria.

Radon, a radioactive gas can increase the risk of lung cancer when breathe in. Indoor Rn-222 and Rn-220 concentrations were determined using passive radon monitor in some dwellings in a Sn mining area of Jos Plateau. Outdoor gamma radiation was also measured with a hand-held survey meter. The range of Rn-222 and Rn-220 concentrations was from 7-53Bq m-3 to 41-267Bq m-3 with averages of 27±17 and 92±65Bq m-3, respectively. The mean total effective dose due to Rn-222+Rn-220 was estimated as 2.84±1.57mSv y-1. Rn-220 contributed between 50 and 95% to the total annual effective dose. There was no correlation between indoor Rn-220 and Rn-222 concentrations in the dwellings. Outdoor gamma radiation measured was between 0.31±0.06 and 0.62±0.08μSv h-1, and mean annual effective dose calculated was 1.14±0.21mSv y-1. It is concluded from this study that thoron should not be neglected in dose assessment.

Assessment of environmental radioactivity concentration and effective dose rates from radon gas exposure from water samples in Gezira State, Sudan

A study was conducted in Gezira State, Sudan, to estimate the concentration of radon and the annual effective dose rate in water samples based on inhalation, ingestion, and age group. The study collected 26 samples from different locations. The results showed that the mean concentration of radon was 7.68 ± 1.07 Bq.l−1, and the mean effective dose rate of radon released from water to indoor air was 19.17 ± 2.68 μSv.y−1. The average effective dose rates calculated from ingestion, inhalation, and the total annual effective dose rate were 18.81 ± 2.63, 19.34 ± 2.71, and 38.15 ± 5.34 μSv.y−1, respectively. The annual effective dose rates for infants, children, and adults were calculated to have mean values of 80.60 ± 11.27, 53.73 ± 7.51, and 38.38 ± 5.37 μSv.y−1, respectively. The study found that 23.1% of the samples exceeded the maximum contamination level, while 76.9% were below the reference levels set by the USEPA, WHO, and EU. Despite the increase in radiation dose with age and consumption rates, the radiation dose from water was lower than the recommended limits set by UNSCEAR and WHO. Additionally, the bronchial epithelium received twice the radiation dose compared to the stomach walls.

Annual Effective Dose Estimation from Radon Concentration in Commonly Consumed Bottled Water in Northcentral Nigeria

Radon (222Rn), the heaviest among the noble gas in the periodic table of element, is radioactive nuclide that is naturally available in rocks, soil and water. In this study, a total of ten (10) brands of commonly consumed commercial bottled water in northcentral Nigeria were collected and assigned for their radon concentration using liquid scintillation counter (LSC). The highest radon (222Rn) concentration of 0.073 Bq/l was recorded in C Way bottled water while Mr. V bottled water recorded the lowest 222Rn concentration value of 0.016 Bq/l. These values were below the parametric reference level of 11.1 Bq/l set by United State of America Environmental Protection Agency and lower than the permissible limit of 100 Bq/l by World Health Organization (WHO) and European Union. Computed total annual effective dose due to ingestion and inhalation of waterborne radon recorded the highest mean value of 0.187 μSv/y in C Way Bottled water and lowest value of 0.041 μSv/y in Mr. V bottled water. Mean total annual effective dose recorded for all the bottled water samples were found to be significantly lower than the safety limit of 0.1 mSv/y recommended by WHO. The likelihood of any radiation incidence among the public due to consumption of commercial bottled water is therefore negligible.

Radon Concentration in Air and Evaluation of the Radiation Dose in Villages near Shizhuyuan, Southern Hunan, China

Radon is one of the important natural sources of radiation and pollutants. When radon and its progeny are inhaled by the human body, they can cause radiation damage to the respiratory system and can lead to lung cancer. Indoor and outdoor radon concentrations were measured in five villages near Shizhuyuan W-polymetallic deposit using a RAD7 detector; moreover, the corresponding radiation dose and lifetime risk probability were evaluated. The results show that the average value of indoor radon concentration was 216.6±121.1 Bq m−3, which is above the worldwide average indoor radon level of 40 Bq m−3, and the average outdoor value was 34.6±13.4 Bq m−3, which is higher than the worldwide outdoor average of 10 Bq m−3. A total of 42% of the dwellings investigated in our study had a higher radon level than the Chinese permissible indoor radon level of 200 Bq m−3. The total annual effective dose ranged from 5.21 mSv y−1 to 49.38 mSv y−1, with an average value of 14.63 mSv y−1, which is higher than the ICRP recommended value of 3–10 mSv y−1. This average total dose value corresponds to an average lifetime risk probability of 5.8% for residents in the whole study area.

Contribution of Thoron and Its Progeny to the Effective Dose by Inhalation in the Uranium-Thorium Bearing Regions of Mayo Kebbi and Guéra in Chad

Abstract In recent years, technological developments and hypotheses made by some researchers have revealed that the effective inhalation dose from thoron and its progeny was underestimated. This study uses direct measurements to show the significant contribution of thoron progeny to the effective inhalation dose. To achieve this, radon-thoron discriminative detectors (RADUET) and thoron progeny monitors were used for the simultaneous measurement of radon, thoron, and thoron progeny in 150 selected houses in the townships of Bitkine, Mongo, Léré, and Pala in southern Chad. By solid-state detection, concentrations of radon, thoron, and thoron progeny were measured and associated effective doses evaluated. The mean concentrations of radon, thoron, and thoron progeny were 62 (1), 60 (2), and 7.6 (2.1) Bq m−3, respectively. These concentrations are above the corresponding global average values. The equilibrium factor of the thoron varied considerably from one municipality to another. The average total annual effective dose by inhalation was estimated to be 4.23 mSv. The contribution of thoron and its progeny to the total inhalation dose ranged from 5% to 86% with an average of 62%. Considering the above, public exposure to thoron and its associated progeny is a public health concern in a similar way to radon.

Po-210 in plankton and fish from coastal waters (gulf of Trieste, northern Adriatic Sea)

The activity concentrations of Po-210 were determined in seawater (<0.45 μm), suspended particulate matter (0.45–20 μm), fractionated plankton (20–50 μm, 50–200 μm, >200 μm) and tissues from four fish species, namely European seabass (Dicentrarchus labrax), Golden grey mullet (Chelon auratus), Gilt-head bream (Sparus aurata) and Common pandora (Pagellus erythrinus), collected in the Gulf of Trieste (northern Adriatic Sea). The activity concentration of Po-210 in seawater varied from 0.4 to 2.2 mBq/L in the dissolved phase (<0.45 μm) and from 0.4 to 0.8 Bq/L in suspended particulate matter (0.45–20 μm). Plankton fractionation showed the levels of 62–395 Bq/kg Po-210 in the >200 μm mesoplankton fraction, 65–459 Bq/kg in 50–200 μm and 52–537 Bq/kg in 20–50 μm microplankton fractions. No significant differences were found between fractions. The Po-210 distribution trend in fish tissues was in order: liver > stomach with intestine > kidney > spleen > gonads > gills > muscle. Bioaccumulation factors were determined for fish tissues indicating that the amount of Po-210 mostly depends on fish feeding habits. Hence, the main pathway entry of Po-210 is through ingested food. The highest estimated average total annual effective ingestion doses of Po-210 are obtained via the consumption of Common Pandora (7.1 μSv/year to 16.5 μSv/year) while the lowest doses are due to the consumption of European seabass (0.32 μSv/year to 0.76 μSv/year). Comparison with levels reported for other Mediterranean and Atlantic areas showed that only activitiy concentrations of Po-210 in fish appear significantly different, most likely because different fish species were analysed. The human dose exposure via fish consumption in the area is rather low.

Health Impacts of Natural Background Radiation in High Air Pollution Area of Thailand.

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.

Measurement of Natural Radioactivity in Fly Ash from a Lignite-Fired Thermal Power Plant and Radiological Risk Assessment Using RESRAD Code

In this study, the activity concentrations of natural primordial radionuclides in fly ash (FA) samples collected from the landfill area of Afşin-Elbistan A lignite-fired thermal power plant (AE-A LFTPP) located in Kahramanmaraş province of Türkiye were measured using a gamma-ray spectrometer. Also, the radiological risk was assessed using the Residual Radioactivity Onsite 7.2 code. The average activity concentrations of 226Ra, 232Th and 40K in FA samples varied from 291 ± 10 to 853 ± 25 Bq/kg, 23 ± 1 to 125 ± 4 Bq/kg and 112 ± 10 to 315 ± 18 Bq/kg, respectively. The predicted maximum total annual effective dose rate due to the natural radionuclides and their progenies is 4.7, 4.4, and 4.0 mSv/y at t = 1000 y for 0.5-m, 1.25-m, and 2.0-m cover scenarios, respectively. While the predicted maximum total cancer risk is 4.56 × 10−3 (3.95 × 10−3 for 226Ra, 5.18 × 10−4 for 232Th and 6.14 × 10−15 for 40K), 4.00 × 10−3(3.80 × 10−3 for 226Ra, 1.90 × 10−4 for 232Th and 7.69 × 10−15 for 40K) and 3.71 × 10−3 (3.71 × 10−3 for 226Ra, 1.820 × 10−8 for 232Th and 7.66 × 10−15 for 40K) at t = 1000 y for 0.5-m, 1.25-m and 2.0-m cover scenario, respectively. Results also revealed that the total doses and cancer risks are less in thicker cover scenarios throughout the 1000 y time span and that 226Ra is the major contributor to the risk in all the scenarios owing to its higher activity concentration than 232Th and 40K.

Determination of 40K, 238U and 232Th Activity Levels in Fishes from River Kubanni in Nigeria

Radionuclides exist naturally in the water, soil and air and human activities can increase the concentration of background radiation and redistribution of radioactive isotopes in the environment. In this study, the radioactivity concentration of three radionuclides (40K, 232Th and 238U) was measured in three fish species, Oreochromis niloticus (Tilapia), Brycinus leuciscus (Kawara), Brienomyrus longianails and Clarias anguilaris (catfish) in river Zaria (Kubanni). The results showed that 40K and 232Th concentrations were high in Brienomyrus longianails with mean activities of 357.26 and 92.282 Bq/Kg, respectively. While the concentration of 226Ra was found high in Clarias anguilaris (56.129 Bq/Kg). The mean committed dose for both adults and children were 0.00214 and 0.00342 µSv/Yr, respectively. The values of three radionuclides obtained in this study are lower than the maximum permissible level of 1.0 mSv/yr recommended by the International Commission on Radiological Protection (ICRP) as the total annual effective dose for the public. The obtained results show that the radiation dose acquired from the consumption of fresh fish from the river Kubanni will have no significant health effect on the populace.

Evaluation of the terrestrial radionuclides and the occupational effective doses at a phosphate mills

Phosphate rocks are the raw materials for fertilizer production. This study aims to evaluate the occupational radiological hazards associated with phosphate rock processing. The average activity concentrations were 825 ± 41, 166 ± 8.3, 12 ± 0.6, and 1333 ± 67 (Bq/kg) for U-238, Ra-226, Th-232, and K-40 respectively. All these concentrations are typical for phosphate rocks. The average absorbed dose rate is 139 ± 7 (nGy/h), which is higher than the worldwide average, reflecting the relative high concentrations of U-238, Ra-226, and K-40. The average total annual effective dose is 0.53 ± 0.03 (mSv/y). All the radiological parameters are lower than the recommended limits.

Assessment of radiation exposure in the phosphate mining area of Gafsa (Southeastern Tunisia)

ABSTRACT This study investigates the radiological health implications of sixty-three (63) samples of soil, food, and drinking water collected from the phosphate mining area of Gafsa in Southeastern Tunisia. Additionally, it assesses the exposure to radon concentrations in houses located around the phosphate mining sites. The activity concentrations in soil samples were found to be 382.1, 36.1 and 16.3 Bq kg−1 respectively for 40K, 232Th and 226Ra. The average activity of 232Th was higher than worldwide average value of 30 Bq kg−1. Eleven (11) radiological hazard parameters were computed based on various exposure scenarios including external gamma dose rate (GDR), annual effective dose (AED) and risk assessment (RA). The calculated GDR values were of 3.2 nGy h−1 in food and 45.4 nGy h−1 in soil samples, while the average AED values were of 3.9 µSv y−1 in food and 83.5 µSv y−1 in soil samples. Internal AED due to ingestion of radionuclides was found to have a mean value of 0.1 µSv y−1 in soil, 264.4 µSv y−1 in food and 10 µSv y−1 in drinking water samples. The AED values due to inhalation of soil-dust and radon were assessed to be 2.1 and 1.2 µSv y−1, respectively. The RA average values in food and drinking water samples were found to be 3 × 10−5 and 2.4 × 10−4, respectively. Based on the exposure pathway, inhalation of radioactivity through soil and radon resulted in highest total AED values, which remained below the reference limit. This was followed by internal exposure, with total AED values of 274.5 µSv y−1.