Values Of Annual Effective Dose Research Articles

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.

Assessment of Excess Life Cancer Risk from Radon Concentration in Borehole water Samples collected from Katagum LGA, Bauchi State, Nigeria

Radon in potable water has turned out to be an issue of public health concerns, specifically when used immediately from supply for  domestic purpose and consumption without any pretreatment. In this study, 222Rn Concentration in 15 water samples collected from  ground water sources (borehols) in Katagum local government Bauchi State was determined, using Liquid scintillation counter (Tri-Carb- LSA1000) and the radiological risk was calculated. The study revealed that, 222Rn concentration ranges from 28.44 to 49.61 Bql-1 with  mean value of 39.55 Bql-1. These values were found to be higher than the permissible limits set by WHO, USEPA and UNSCEAR. The mean  value of annual effective dose due to ingestion for different age categories (adults, children and infants) are 0.29, 0.43 and 0.51 mSvy-1  respectively; and for inhalation the mean is 0.1 mSvy-1. Also, the mean value of excess life cancer risk due to ingestion for different age groups (adults, children and infants) are 0.0010, 0.0015 and 0.0018 respectively while that of inhalation is 0.0003. Thus, this study reveals  that borehole water around Katagum Local Government Area Bauchi State is not radiologically safe and there is need for constant  monitoring. 

Risk assessment of radon exposure inside residential dwellings in Safi city, Morocco

ABSTRACT A radon study was conducted in 50 residences in Safi city, Morocco, using LR-115 detectors. The annual effective dose and Excess Lifetime Cancer Risk were also estimated. The measured radon concentrations ranged between the Lower Limit of Detection (LLD) and 132 Bq.m−3 with an arithmetic mean of 53 Bq.m−3 and a geometric mean of 41 Bq.m−3 (2.32). The results indicated that 58% of the obtained values exceeded the worldwide average value (39 Bq.m−3). In addition, the results revealed significant impacts of floor level and region on indoor radon levels. Inhabitants of the surveyed houses were found to receive a mean annual effective dose of 1.5 ± 0.1 mSv.y−1, corresponding to an Excess Lifetime Cancer Risk of 0.6%. Importantly, all annual effective dose values were below the recommended action level by the ICRP (3–10 mSv.y−1). Using the Ordinary Kriging method implemented in the QGIS software, an indoor radon map was created based on the collected data. The findings in this study serve as baseline values for future studies concerning radon concentrations and their fluctuations.

Radiological Risk to Inhalation of Thoron Gas from Medical Materials Samples Derived from Medical Plants in Iraq

Pollution by thoron is one of the factors that is harmful to human health. Medical materials, especially those derived from plants, have natural ingredients which are a major source of natural radioactivity, thoron being one of them. Therefore, the presence of harmful radioactivity in these materials is a matter of concern. This study determined the concentrations of thoron (220Rn or radon-220) from 70 samples of medical materials derived from medical plants using a CR-39 detector. Samples are drugs (solid), skin creams, herbs, toothpaste, drugs (liquid), and cosmetic products found in Iraqi pharmacies. Also, radiological risks such as Annual Effective Dose (AED), Excessive Lifetime Cancer Risk (ELCR), and Lung Cancer Case (LCC) due to inhalation of thoron from medical materials samples in pharmacies were calculated. The results show that the results of the thoron  concentrations in the samples of medical materials ranged from 1.02 Bq/m3 to 74.53 Bq/m3, with an average value of 18.21 ± 2.00 Bq/m3. The range values of AED, ELCR (×10-3) and LCC (×10-6) were 0.01-0.588 mSv/y, 0.04-2.36, and 0.18-10.58, respectively. It was als found that the thoron concentrations in samples of the present study vary from a minimum of 12.82 Bq/m3 in cosmetic products samples to a maximum of 30.29 Bq/m3 in herbs samples. Nonetheless, all thoron and radiological risk values were lower than the acceptable world limit (thoron = 200-300 Bq/m3  by ICRP and AED = 1.1-4.4 mSv/y by UNSCEAR).

Radon Concentrations in the Environments of Some Primary Schools in Khidir City, Al-Muthanna Province, Iraq

Indoor radon concentrations in 13 primary schools were conducted in Khidir City, Muthanna Province, Iraq, using LR-115 solid-state nuclear track detector type II. The study aims to estimate indoor radon levels in the internal environment of the classrooms for three months (from 1st September to 30th November 2023). Radon concentrations were varied from (0.1 Bq/m3) to (14.13 Bq/m3), with a mean value of (5.61 Bq/m3). The investigated levels were lower than the permissible limits referenced by UNSCEAR and WHO. Moreover, the annual effective dose (AED) has been calculated due to inhalation, which varied from the value of (0.029352 mSv/yr) to the value of (0.081145 mSv/yr), with a mean value of (0.016205 mSv/yr). AED values obtained were found to be lower than the allowed value of (0.1 mSv/yr) reported by UNSCEAR and much lower than the permissible limit (1 mSv/yr) proposed by WHO. However, the results obtained indicate that the indoor radon concentrations were significantly affected by the floor level of the classroom (negatively correlated) and the school building age (positively correlated). Consequently, all results have revealed that the radon concentrations and the associated inhalation radon dose does not pose any kind of health hazard to the occupational stuff and students.

The distribution of natural radionuclides 40K, 228Ac, and 226Ra on Romanian Territory: a radiometric study.

To estimate the radiation hazard due to the natural terrestrial radioactivity, 598 samples of soil covering the entire Romanian territory were collected and analyzed for the distribution of natural radionuclides 40K, 228Ac, and 226Ra. The ultra-low background Slanic-Prahova underground laboratory was used to determine the gamma-ray-specific activity of these radioactive isotopes with an uncertainty between 5 and 20%. All these data permitted to establishing a set of 2D maps illustrating the distribution of specific activity of each radionuclide as well as of the resulting air dose rate, all of them illustrating an heterogeneous distribution, increased values being displaced on the western and south-western territory. Mediated over 598 points, these determinations led to a value of annual effective dose of 0.7 ± 0.15 mSv/y and an external hazard index of 0.46 ± 0.1, both attesting to a radioecologically safe environment for human activity.

Age-dependent annual effective dose and radiological health risk from salt and soil collected from Padag, Chaghi, Balochistan, Pakistan

ABSTRACT This study aimed to investigate the annual effective dose for different age groups and health hazards associated with natural radioactivity in salt and soil collected from Padag, Chaghi, Balochistan. All samples were analysed by using high-purity germanium (HPGe) and sodium iodide (NaI) detectors. The average values of concentration of 226Ra, 232Th and 40K in salt samples were found to be 10.49, 9.6 and 169.65 Bq.kg−1, respectively, using HPGe detector, while in case of NaI detector, these values were found to be 10.48, 9.89 and 161.73 Bq.kg−1, respectively. Similarly, the average values of concentration of 226Ra, 232Th and 40K in soil were found to be 24.59, 24.89 and 391.72 Bq.kg−1, respectively, using HPGe detector, while in case of NaI detector, these values were found to be 24.46, 24.71 and 358.31 Bq.kg−1, respectively. Significant correlations were found between the results obtained from HPGe and NaI detectors. The values of total annual effective dose due to ingestion of salt were found to be 2.46 × 10−5, 2.45 × 10−5, 3.55 × 10−5 and 1.13 × 10−5 μSv.y−1 using HPGe detector and 2.43 × 10−5, 2.44 × 10−5, 3.55 × 10−5 and 1.13 × 10−5 μSv.y−1 using NaI detector for the age groups (2–7 years), (7–12 years), (12–17 years) and (≥17 years), respectively. The highest value of annual effective dose was found in the age group 12–17 years and minimum was found in the age group ≥ 17 years. However, all values were found to be below the recommended value of 0.29 mSv. Total average radiological risk due to ingestion of salt for all age groups was found to be lower than the reported value.

Evaluation of radiological health risk due to ingestion and inhalation of radon in commercial packaged fruit juices consumed in Turkey

ABSTRACT Fruit juices (FJs) are among the most popular beverages frequently preferred by consumers, believing FJs contain the nutritional values, minerals, phytochemicals, vitamins, and antioxidants necessary for a healthy life. However, FJs may contain natural radionuclides such as radon (222Rn), which originates from the fruit and water utilized in their production, at levels that may pose a health risk to people. Inhalation and ingestion of 222Rn gas increases the risk of lung and stomach cancer. In this study, commercially packaged FJs from the seventeen most popular brands consumed in Turkey were analyzed for physicochemical properties and 222Rn activity concentrations to evaluate the radiological health risk. The values of pH, brix and 222Rn activity concentrations in FJ samples varied from 2.68 to 4.28, 2.50 to 14.30%, 9.6 ± 1.1 to 25.2 ± 2.5 mBq/L, respectively. The radiological health risk caused by internal exposure was evaluated for children and adults by estimating the ingestion and inhalation annual effective dose. The average values of the total annual effective dose for children and adults were found as 0.039 µSv and 0.056 µSv, respectively, which are much lower than the recommended dose of 100 µSv for drinking water.

Measurement of radium and radon gas in bottled mineral waters.

In this study, the radon gas and radium concentration in the bottled mineral water samples was measured. A total of sixty samples were collected from bottled mineral water sold in the markets in Kahramanmaraş. DURRIDGE Rad7 electronic radon detector was used for measurements. Radon and radium activity amounts range from 33.50 ± 1.30mBq/L to 51.70 ± 2.20mBq/L, and 2.92 ± 0.15mBq/L to 4.51 ± 0.26mBq/L, respectively. Average radon and radium active amounts are 41.67 ± 1.54mBq/L and 3.63 ± 0.18mBq/L, respectively. Total annual effective dose values were calculated for these mineral waters according to three different scenarios. In the first of these, it was assumed that natural mineral water was consumed annually instead of 730 L of drinking water (S1). In the second case, 150 L which was the annual average amount of natural mineral water consumed in European Union member countries was used for the annual average amount of natural mineral water consumed by adults (S2). Finally, the annual average amount of natural mineral water consumed in Turkey, 14 L, was used for adults (S3). For scenarios (S1, S2, S3), the total (ingestion + inhalation) annual average dose values ranged from 6.83E-04mSv/y to 1.05E-03mSv/y, 1.40E-04mSv/y to 2.17E-04, and 1.32E-05mSv/y to 2.03E-05mSv/y, their average values were 8.49E-04mSv/y, 1.75E-04mSv/y, and 1.64E-05mSv/y, respectively. The total effective dose values calculated within the scope of the current study were below the limit value announced by WHO.

Working conditions and values of average annual effective doses for nondestructive testing operators in the Russian Federation and abroad

The review presents description of the work and the main provisions on the working conditions for nondestructive testing operators from the standpoint of the system for ensuring radiation safety and radiation control. The values of the average annual effective doses of flaw detectorists in the Russian Federation and abroad are indicated. Official sources of information on doses in the Russian Federation and in the world, obtained from the results of individual dosimetric monitoring, were selected for presentation. The data of our own measurements were not included in this review. The difference in the name of the specialty of the studied group of personnel in Russian and English and the difference in the processing of primary measuring information in domestic and foreign sources of information are taken into account. The relevance of the need to resolve the issues of radiation safety and radiation monitoring of personnel involved in nondestructive testing is demonstrated, due to the fact that in the Russian Federation there are regulatory and methodological documents affecting the organization and conduct of individual dosimetric monitoring of personnel in the medical field and the nuclear industry, but they do not include personnel conducting nondestructive testing. Therefore, individual dosimetric control for nondestructive testing operators is carried out by accredited laboratories in accordance with the provisions of Methodical guidelines 2.6.1.3015-12.“Organization and management of individual dosimetry of medical staff”, i.e. without taking into account the exposure scenarios for personnel involved in nondestructive testing and the specifics of it work. The doses estimated in this way are included in the regional and federal databanks of personnel exposure doses. When entering dose values into data banks, there is no division of personnel into the personnel performing nondestructive testing in stationary and nonstationary conditions, therefore, the doses of personnel performing various types of nondestructive testing are averaged.

A Review of Radon Concentration in Water Sources in Nigeria and its Impact

Given the characteristics of radon, people may unwittingly be exposed to radon through water ingestion. Research on radon concentration has increased over the years due to its negative impact on the body being the major causes of lung cancer. This study reviewed twenty (20) journal publications on radon concentration in water sources (such as well, boreholes, stream and taps) in Nigeria from year the 2016 to 2023. The type of sample, sample location, devices used, the range and mean values of radon concentration (RnC) and annual effective dose (AED) were considered. From the reviewed journals, the average values of RnC ranged from 1.9 Bq/L to 88.0 Bq L-1. When compared with WHO and US EPA recommended limits of 100 Bq L-1 and 11.1 Bq L-1 respectively, all reviewed journals recorded average values of RnC below 100 Bq L-1 and 75 % of the reviewed journals recorded average values of RnC above US EPA recommended limit of 11.1 Bq L-1. The mean AED reported is within the range of 0.02 mSv yr-1 and 92 mSv yr-1 with 30 % above the recommended limit of 0.1mSv yr-1. This result shows that the majority of the radon concentration in water sources in Nigeria reported may not pose any immediate health risk. However, there is a need for continuous monitoring and protective measures to be taken.

ASSESSMENT OF NATURAL RADIONUCLIDES IN SOIL SAMPLES FROM MICHIKA, ADAMAWA, STATE NIGERIA

Naturally occurring radionuclides in the environment constitute about 85% of public exposure to terrestrial gamma radiation. These radionuclides can be found in sands,clays, soils and rocks, and many ores and minerals, commodities, recycled residues, and other appliances used by humans. There is therefore the need to assess the occurrence of natural radionuclides in Soil Samples from Michika, Adamawa State Nigeria. Forty-six (46) soil samples were collected across different location in Michika, Adamawa State, Nigeria. Gamma ray spectroscopy was used for the analysis. The results obtained show that the mean activity concentration for 226Ra, 232Th and 40K are 81.27, 101.28 and 324.79 Bq/kg respectively. These values are higher than the control value of 35,30 and 35 Bq/kg for 226Ra, 232Th and 40K set by UNSCEAR. The absorbed dose rate (D) ranges from 60.77 to 248.65 nGy/h, which is above the maximum UNSCEAR accepted value of 59nGy/h. The values of total annual effective dose lie between 0.08 and 0.31 mSv y-1 with mean value of 0.14mSv y-1. Also, the mean values of Radium Equivalent Activity were 251.11 Bq/kg. Almost all the value of Raeq were below the maximum recommended value. The mean value of total cancer risk range from 3.28E-6 to 1.3E-5 with mean value of 5.93E-6. All the mean values were above the acceptable range. It can be concluded that the soil is radiologically unsafe for human and animal use. Continuous radiological monitoring of the soil is recommended to safeguard the health of the populace.

Natural Radioactivity for some Types of Date in Al-Qasim Subdistrict, Babylon Governorate

The aim of the present study is to assess some radiological hazard risk parameters such as the annual effective dose (AED), Fatal Cancer Risk (FCR), Hereditary Cancer Risk (HCR), radium equivalent (Raeq), and Internal hazard index (Hin) due to specific activity of 238U, 232Th, and 40K in some samples of date in Al-Qasim subdistrict, Babylon governorate. The specific activity was measured using gamma-ray spectroscopy with NaI(Tl) doctor. The average values of the specific activity in unit Bq/kg for 238U, 232Th, and 40K were 10.83 ±1.22, 4.94 ±0.80, and 341.36 ±15.25, respectively. While, the average values of total AED, FCR×10-3, HCR×10-3, Raeq, and Hin were 0.210±0.018 mSv/y, 0.737±0.064, 0.198±0.008, 44.18±3.10 Bq/kg, and 0.148±0.011, respectively. The results show that, all values of 238U, 232Th, and 40K were lower than the global limit according to UNSCEAR 2008 (33 Bq/kg, 45 Bq/kg, and 420 Bq/kg), except two samples have 40K higher than global limit. these because increasing used chemical fertilizers by peasants. Also, it is found that all values of the radiological hazard risk parameters in the present study were lower than global limit according to UNSCEAR, ICRP, OECD, etc. So, it was concluded that the date samples in the present study does not cause any danger to the human health when its consumption.

Radon Assessment in Water Samples in a University Community in Osogbo Osun State

Introduction: Radon is a radioactive gas and one of the leading causes of cancer at high concentrations globally. Inhalation or ingestion of radon-contaminated water through drinking, cooking, or bathing has reportedly increased human health risks. Measuring radon levels in water helps assess the potential health risks associated with ingestion and inhalation. Aims: In this study, the assessment of radon activity in water in some selected places within a university community in Osogbo, Osun State, Nigeria, was carried out. Materials and Methods: Fifteen (15) water (groundwater and borehole water) samples were collected, and the radon concentration was measured using a DURRIDGE RAD7 H2O accessory radon detector. Results: The results of the radon activity ranged from 6.3 ± 1.7 Bq/L to 60.8 ± 5.6 Bq/L with a mean of 21.33 ± 2.95 Bq/L. Nine (9) out of the fifteen (15) water samples measured were observed to be higher than EPA’s maximum contaminant level of 11.1 Bq/L, while the other six (6) water samples were within the range. The annual effective dose values lie within 3 -10 mSv/yr., reported by the International Commission on Radiological Protection. Conclusion: Water within the university community in Oshogbo, Osun State, is recommended for regular radon monitoring due to the high radon concentration above the Nigerian Standard for Drinking Water Quality. To Keywords: radon, Osogbo, water, RAD7 H2O

A study on measuring the 222Rn in the Buriganga River and tap water of the megacity Dhaka.

Radon (222Rn), an inert gas, is considered a silent killer due to its carcinogenic characteristics. Dhaka city is situated on the banks of the Buriganga River, which is regarded as the lifeline of Dhaka city because it serves as a significant source of the city's water supply for domestic and industrial purposes. Thirty water samples (10 tap water from Dhaka city and 20 surface samples from the Buriganga River) were collected and analyzed using a RAD H2O accessory for 222Rn concentration. The average 222Rn concentration in tap and river water was 1.54 ± 0.38 Bq/L and 0.68 ± 0.29 Bq/L, respectively. All the values were found below the maximum contamination limit (MCL) of 11.1 Bq/L set by the USEPA, the WHO-recommended safe limit of 100 Bq/L, and the UNSCEAR suggested range of 4-40 Bq/L. The mean values of the total annual effective doses due to inhalation and ingestion were calculated to be 9.77 μSv/y and 4.29 μSv/y for tap water and river water, respectively. Although all these values were well below the permissible limit of 100 μSv/y proposed by WHO, they cannot be neglected because of the hazardous nature of 222Rn, especially considering their entry to the human body via inhalation and ingestion pathways. The obtained data may serve as a reference for future 222Rn-related works.

Natural radioactivity Measurements of Dur-Kurigalzu's Ziggurat, Baghdad Governorate-Iraq using HPGe detector

       Measurement of 238U, 233Th and 40K concentrations in soil samples collected from Ziggurat of Dur-Kurigalzu west region of Baghdad, have been evaluated, using high purity germanium detector. The activity concentrations of 238U, 233Th and 40K varied from 16.040  to 26.620 , 14.510  to 31.480 , and 153.820  to 266.320  with average values of 20.604±2.9 , 24.534±3.3 , 212.22±25.1 , respectively. The importance of these measurements lies in the estimation of radiation risk, radium equivalent, absorbed dose, annual effective dose, risk indices, gamma index, and cancer risk. The average value of the absorbed dose ranged from 33.187  outdoors to 63.111  indoors. The mean annual effective dose value was estimated to be 0.043  outdoors and 0.310  indoors from the study area. The total calculated lifetime risk of cancer ranged from 0.991×10-3 to 1.485×10-3, while the indoor lifetime cancer risk exceeded the recommended limit in samples 6, 8, 9, and 10.  The areas examined in this study showed radioactive contamination less than the internationally permissible limits for the sites inhabited by the population.

Evaluation of Uranium Concentration and Calculated Doses of Radiation Resulting From the Tap and Bottled Drinking Water in Babylon - middle Iraq

      In this study, uranium concentrations were evaluated and the annual effective dose was calculated from the consumption of bottled water and tap water used for drinking in Babylon, middle Iraq. Uranium isotopes (238U, 234U, 235U) were determined for all samples collected using the phosphorylation analyzer technique represented device (KPA). Forty-four samples were collected to cover almost all districts and regions of Babylon.  Thirty tap water samples were collected from residential neighborhoods, with 14 samples from local brand bottled water. The results show that the uranium concentrations in the tap water samples ranged from 1.66 μg.L-1 to 2.64 μg.L-1, with an average of 2.12 μg.L-1, and the bottled water samples varied from 1.06 μg.L-1 to 1.82 μg.L-1, with an average 1.47 μg.L-1. This means that the uranium contents in tap and bottled water samples are less than 15 μg.L-1 and 30 μg.L-1, which are safe values of the WHO, and the EPA respectively. The annual effective dose values of 238U, 234U, and 235U for adult consumption of tap water range between 0.67, 0.0.33, 0.74 μSv.y-1 to 1.07, 0.052, 1.18 μSv.y-1 with averages of 0.86, 0.042, 0.95 μSv.y-1, respectively. Their values in bottled water ranged from 0.43, 0.020, 0.47 μSv.y-1 to 0.73, 0.035, 0.81 μSv.y-1, with an average of 0.59, 0.029, 0.65 μSv.y-1, respectively. The value of the annual effective dose of total uranium isotopes in tap water samples ranged between 1.45 μSv.y-1 to 2.30 μSv.y-1 with an average of 0.85 μSv.y-1, whereas in bottled water varied from 0.92 to 1.58 μSv.y-1 with an average of 1.28 μSv.y-1.

DETERMINATION OF RADON ACTIVITY CONCENTRATIONS IN SOME WELL WATERS NEAR THE AKŞEHIR-SIMAV FAULT SYSTEM AND ESTIMATION OF MEAN ANNUAL EFFECTIVE DOSES.

Radon concentrations were measured in four-well and spring water, which is used as drinking water, in the villages and districts of Afyonkarahisar province near Akşehir-Simav fault system for 24 month period, and the annual average effective dose amounts were calculated. In addition, the relationship between the average radon concentration results of potable water wells and the distance of the wells to the fault was examined for the first time in this region. Mean radon concentrations were measured between 1.9±0.3 and 11.9±0.5Bql-1. The annual effective dose values were calculated between 11±1.7 and 70.1±2.8μSvy-1 for infants, 4.0±0.6 and 25.7±1.0μSvy-1 for children and 4.8±0.7 and 30.5±1.2μSvy-1 for adults. In addition, the effect of the distance of the wells from the fault on the mean radon concentrations was also investigated. The regression coefficient (R2) was calculated as 0.85. The average radon concentration was observed higher in the water wells close to the fault. The highest mean radon concentration was measured in well no. 4, closest to the fault and 1.07km away.

Effective dose (ingestion and inhalation) due to radon from tap water samples in children at primary schools in Najaf city, Iraq

Abstract This study focuses on the evolution of radon concentrations in tap water samples of primary schools in Najaf city using a RAD-7 detector. Annual effective doses in children were calculated. A Geographic Information System technique was used for the mapping of radon concentrations, annual effective dose (AED) for ingestion, and inhalation. It was found that the average value of AED due to radon ingestion was 0.236 ± 0.020 μSv/year, while that due to radon ingestion was 0.015 ± 0.0001 nSv/year. Moreover, the range in value of the total AED in μSv/year was 0.015–1.171, with an average value of 0.236 ± 0.020. Radon concentrations in most samples of water comply with the world-wide limits that are approved by WHO and ICRP which state that safe limits (0.5 and 0.4 Bq/L), respectively. Furthermore, all results of the total AED due to radon ingestion and inhalation assessment from radon concentrations in tap water samples collected from the primary schools in Najaf city when used as drinking water were within the global limitations of the WHO. One may conclude that from the results of the AED in children (7–12 years), there is no danger of radon concentrations in the case of human consumption.

Assessment of occupational radiation exposure of NORM scales residues from oil and gas production

Radiological hazards from external exposure of naturally occurring radioactive materials (NORM) scales residues, generated during the extraction process of oil and gas production in southern Algeria, are evaluated. The activity concentrations of 226Ra, 232Th, and 40K were measured using high-purity gamma-ray spectrometry (GeHP). Mean activity concentration of 226Ra, 232Th and 40K, found in scale samples are 4082 ± 41, 1060 ± 38 and 568 ± 36 Bq kg−1, respectively. Radiological hazard parameters, such as radium equivalent (Raeq), external and internal hazard indices (Hex, Hin), and gamma index (Iγ) are also evaluated. All hazard parameter values were greater than the permissible and recommended limits and the average annual effective dose value exceeded the dose constraint (0.3 mSv y−1). However, for occasionally exposed workers, the dose rate of 0.65 ± 0.02 mSv y−1 is lower than recommended limit of 1 mSv y−1 for public.