Raeq Values Research Articles

Cancer Risk Due to the Natural Radioactivity in Cigarette Tobacco

Thirty-one samples of cigarettes have been collected from local markets of different types of origins. The samples were selected according to a survey distributed to smokers by paper and digital survey to see the most heavily traded among smokers and in addition to a number of questions to see how the awareness and the culture of smokers in diseases caused by smoking and considered this study the first survey in Iraq. The aim of this research is to assess the number of cancer cases due to cigarette smoking. Through the use of High-Purity Germanium system (HPGe) (efficiency 40%) we determinated the radionuclides in cigarette tobacco. The average values were (14.86 ± 3.76, 10.84 ± 3.13, 1050.64 ± 47.57) Bq/kg for Ra-226, Th-232 and K-40, respectively, and the excess lifetime of cancer risk values ranged from 0.54 to 130 at average of 76 per million person per year. Raeq values varied from 18.50 to 87.21.4 Bq/kg with an average value of 39.51 Bq/kg for tobacco samples. The annual effective dose (HE) varies from 16.38 μSv/y to 44.69 μSv/y with an average value of 24.97 μsv/y. The Annual Gonadal Dose Equivalent (AGDE) varies from 0.3 to 0.64 (mSv/y) with an average value of 0.42 for all tobacco samples under investigation.

Determination of Radionuclide Concentrations in Tea Samples Cultivated in Guilan Province, Iran

Introduction Foodstuffs are known to contain natural and artificial radionuclides. Determination of radionuclide concentration is of great significance for the protection of human health. The main objective of the present study was the quantification of radionuclides in tea samples, cultivated in Guilan Province in North of Iran. Materials and Methods The activity concentrations of 226Ra, 232Th, 40K, and 137Cs in 18 tea samples were measured, using a gamma spectrometry system. In addition, radium equivalent index (Raeq) and radiation hazard index (HI) were calculated. ANOVA test was used for the statistical analysis of the data Results The concentration of 137Cs was below the minimum detectable activity (MDA). The concentrations of 226Ra and 232Th ranged from < MDA to 0.042 and < MDA to 0.037 Bq/kg respectively. The mean concentration of 40K was 410±15 Bq/kg. Based on the findings, the concentration of 40K was significantly higher than other radionuclides (P<0.01). Also, the mean Raeq value was estimated at 31.8±1.2 Bq/kg, and HI in the samples ranged from 0.075 to 0.093. Conclusion According to the findings, the activity level of radionuclides in tea samples was found to be within the acceptable range and therefore, non-threatening to public health.

Radiological Hazard Resulting from using Ceramic Tile in Egypt

In this study the radiological hazard Resulting from the using of ceramic tile locally produced and commonly used as building materials in Egypt have been done by determining the contents of natural radionuclides ( 226 Ra, 232 Th and 40 K) by using gamma spectrometry (HPGe) detector. The measured average activity concentrations of 226 Ra, 232 Thand 40 K were 47.4±3.3, 42.84±2.8 and 313.6±34.3 Bqkg -1 respectively. The obtained concentrations were compared with the reported data of other countries. The Raeq values of all samples were lower than the limit of 370Bq.kg -1 , equivalent to a gamma dose of 1.5 mSv.a -1 recommended by OECD. With average total annual dose being only 0.07mSv y -1 , this value is about 7 % of the 1.0 mSv y -1 recommended by the International Commission on Radiological Protection (ICRP-60, 1990) as the maximum annual dose to members of the public.

Natural radionuclides in soil near a coal-fired power plant in the high background radiation area, South China.

In this study, soil samples around Mawan coal-fired power plant (CFPP) in Shenzhen, a high background radiation area in South China, were analyzed for natural radionuclides. The activity concentration of (226)Ra, (232)Th, and (40)K in soils around Mawan CFPP ranged from approximately 72 to 358 Bq kg(-1) (averaged 204 Bq kg(-1)), 118 to 432 Bq kg(-1) (averaged 265 Bq kg(-1)), and 101 to 2168 Bq kg(-1) (averaged 1269 Bq kg(-1)), respectively, being found to be significantly higher than the world range values. The levels of these radionuclides in soil largely decreased with increasing distance from the CFPP, indicating a technologically enhanced natural radiation near the CFPP. The Raeq values for the soil samples around Mawan CFPP ranged from 346 to 878 Bq kg(-1), most of which exceeded the allowed maximum Raeq value of 370 Bq kg(-1). The operating of CFPP has increased the total radioactive dose received for the nearby population.

Assessment of the radiological impacts of treated phosphogypsum used as the main constituent of building materials in Jordan

Phosphogypsum (PG) was treated to reduce activity concentrations of 226Ra, which was found to exceed that permitted by international regulations. Treatment methods using hybrid water treatment, sulphuric acid treatment, mixed acid (H2SO4 and HNO3) treatment, household water treatment and calcium carbonate powder treatment were applied. Reduction of 226Ra content in phosphogypsum by 80–85 % can be achieved using these treatment processes. The radium equivalent activity (Raeq), gamma index (I γ ), alpha index (I α ), absorbed gamma dose rate (D in), and corresponding annual effective dose (E in) were evaluated for public exposure due to the use of treated phosphogypsum in building materials and for other purposes. The calculated values of the (Raeq), (I γ ), and (I α ) for all the treated phosphogypsum samples are significantly below the recommended upper level of unity used as an index of radiological hazard. The measured mean value of the (D in) is about 20 % lower than the population-weighted average value of 84 nGy h−1 for the indoor absorbed dose rate. The estimated values of the indoor annual effective dose for all the treated phosphogypsum samples are significantly below the recommended upper level of 1 mSv. The mean value of the (E in) is about 70 % lower than upper level of 1 mSv. In the overall assessment, it can be concluded that using treated PG in proportions up to 100 % of building materials and other applications will be safe from the radiation protection perspective.

English

This paper presents the finding of a study undertaken to determine the natural radioactivity present in building materials in Pachal of Tiruvannamalai District, Tamilnadu. During this study, the samples of commonly used raw materials for buildings were collected and analyzed for primordial radio nuclides by gamma ray spectrometry using NaI (TI) detector. The specific activities of 226Ra, 232Th and 40K were measured in the samples. The radium-equivalent activity (Raeq) of the samples was calculated and compared with similar data obtained in other countries that are reported in the literature. The comparison reveals that Raeq values obtained in our study area fall far below the criterion limit specified in building materials. The potential radiological hazard of the different samples was estimated using different approaches. These values were compared with the published data and were found to be within the acceptable limits. The results show that these materials are quite safe to be used as building materials.

A study on the impact of phosphate fertilizers on the radioactivity profile of cultivated soils in Srirangam (Tamil Nadu, India)

Phosphate fertilizers are enriched with 238U during its production from phosphate rocks. Since, application of phosphate fertilizers in modern agriculture is ever on the increase, the present study investigated the impact of phosphate fertilizers on the radioactivity profile of cultivated (fertilized) soils as against virgin soils. Thirty soil samples each from cultivated fields and virgin fields were collected from Srirangam taluk and analyzed for the activity concentrations of 238U, 232Th and 40K employing gamma ray spectrometry. Similar analysis was also undertaken in commonly used phosphate fertilizers. Among the phosphate fertilizers analyzed single super phosphate (396.3 Bq/kg) and triple super phosphate (284.2 Bq/kg) registered higher level of 238U. The mean activity level of 238U in cultivated soil (8.4 Bq/kg) was 25% higher than that of virgin soil (6.8 Bq/kg), while the mean 232Th and 40K activities in cultivated soil (98.4 Bq/kg & 436 Bq/kg) were elevated by 12.4% and 4% respectively as compared to virgin soil (87.5 Bq/kg & 419 Bq/kg). The mean radium equivalent (Raeq) value for virgin and cultivated soil samples was found to be 164.5 Bq/kg and 181.7 Bq/kg respectively. It is evident that the application of phosphate fertilizers elevated 238U level of the soil. However, the mean Raeq value for soil samples is well below the permissible limit of 370 Bq/kg and hence cultivated soils do not pose any radiological risk.

Evaluation of radiation dose due to naturally occurring radionuclides in rock samples of different origins collected from Azad Kashmir

The state of Azad Kashmir is rich in three types of rocks, namely, sedimentary, metamorphic, and igneous rocks. These rocks contain extensive deposits of graphite, marble, limestone, quartzite, granite, dolerite, and sandstone, which are widely used for the construction of dwellings in Azad Kashmir and Pakistan. Therefore, knowledge about the presence of natural radioactivity in these materials is desirable to assess the radiological hazards associated with it. In this context, 30 rock samples were collected from different geologic formations of the Muzaffarabad Division, Azad Kashmir. After processing the samples, the specific activities of 226Ra, 232Th, and 40K in them were measured using a P-type coaxial high-purity germanium detector. The observed highest dose rate values for sedimentary, metamorphic, and igneous rocks have been found to be 83.16±1.08, 135.87±1.18, and 115.98±1 nGy ⋅ h–1, respectively. The radium equivalent activity (Raeq) varied from 23.76±1.15 for dolerite sample (igneous rock) to 293.69±2.60Bq ⋅ kg–1 for marble (metamorphic rock). The Raeq values of all rock samples are lower than the limit mentioned in the Organization for Economic Cooperation and Development (OECD, 1979) report (370Bq ⋅ kg–1, equivalent to γ-dose of 1.5mSv ⋅ y–1). The values of external (Hex) and internal hazard indices (Hin) are less than unity. The mean outdoor and indoor annual effective dose equivalents are 0.073mSv ⋅ y–1 and 0.29mSv ⋅ y–1, respectively. The mean (over all types of rock samples) annual effective dose equivalent is reported as 0.36mSv ⋅ y–1.

Radiological exposure assessment from soil, underground and surface water in communities along the coast of a shallow water offshore oilfield in Ghana.

Radiometric determinations have been carried out to assess public exposure to radioactivity for communities along the coast of a shallow water offshore oilfield in Ghana (which started their operations recently) in order to establish baseline data using alpha spectrometry after radiochemical separation and non-destructive gamma spectrometry. The average activity concentrations of (234)U, (238)U, (230)Th and (232)Th by alpha-particle spectrometry and of (226)Ra, (228)Ra, (228)Th, (40)K, (210)Pb, (234)Th and (137)Cs by gamma-ray spectrometry were determined in the soil samples. The activity concentrations of (234)U, (238)U, (230)Th and (232)Th were determined in the water samples by alpha-particle spectrometry and of (226)Ra by liquid scintillation counting. The total annual effective dose to the public was estimated from the measured activity concentrations and this was clearly below the International Commission on Radiological Protection (ICRP) reference level of 1 mSv y(-1) for public exposure control. In addition, the estimated values of Raeq, Hex and Hin were all lower than the recommended acceptable values and the mean values of gross alpha and gross beta determinations performed for all the water samples give values that were all below the Ghana Standards Authority and World Health Organization recommended guideline values for drinking water quality. The results obtained show insignificant public exposure to radioactivity. However, this study provides important information for future studies on subsequent evaluations of the possible future environmental contamination due to activities of the oil industry in Ghana.

Estimation of environmental impacts of NORM from some raw materials used in ceramic industry

Common raw materials used in ceramic industry in Egypt have been collected from different ceramic factories. The samples were tested for their natural radioactivity contents by using HPGe high-resolution γ-ray spectrometer. Various radionuclides of the samples have been identified quantitatively based on their characteristic spectral peaks. The natural radioactivity due to the presence of 238U, 226Ra, 232Th, and 40K and the radiological parameters for 15 raw materials were measured. The three raw materials with the highest radioactivity were quantitatively analyzed using X-ray fluorescence (XRF). The most abundant oxides measured were generally SiO2, ZrO2, ZnO, Fe2O3, and CaO. The highest mean values of 238U, 226Ra, and 232Th activities were 394 ± 6, 428 ± 8, and 61.1 ± 1.5 Bq kg−1 (in zircon), and the highest 40K activity was 283 ± 4 Bq kg−1 (Aswan clay). The radium equivalent activities and some hazard indices were also calculated to assess the radiation hazards. The maximum mean value of the radium equivalent activity Raeq is 516 ± 10 Bq kg−1 (in zircon). The highest radioactivity level and dose rate in air were also obtained for zircon. The total absorbed dose rates in air, calculated from the concentrations of the three radionuclides, range from 4.29 ± 0.18 to 461 ± 9 nGy h−1; the external annual effective dose rates were determined to be between 0.03 ± 0.003 and 4.35 ± 0.23 mSv.

An Analysis for Distribution of Natural Radionuclides in Soil, Sand and Sediment of Potenga Sea Beach Area of Chittagong, Bangladesh

A HPGe (High Purity Germanium) detector based, low background gamma-ray counting system was used for activity measurement in soil, sand and sediment samples collected from Potenga sea beach area of Chittagong, Bangladesh. The specific radioactivities of Radium (226Ra), Thorium (232Th) and Potassium (40K) were measured in the above samples. The investigation reflects the lower deposition of minerals exist in the collected samples. From the measured specific radioactivities of the above three natural radionuclides, the radium equivalent activity (Raeq), the external hazard index (Hex), the external gamma absorbed dose rate and the annual effective dose were calculated. The obtained mean values of gamma absorbed dose rate in soil and sand samples and annual effective dose in soil, sand and sediment samples were found higher than the worldwide average as reported by United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR, 2000). The Raeq values were in the range of 47.86 to 293.76 Bq·kg-1 and the Hex varied from 0.13 - 0.81, which indicated that the study area was radiologically safe for human being.

Radioactive element contents of some granites used as building materials: insights into the radiological hazards

This study was conducted to investigate the radioactive potential hazard of granite, which is widely used as building material in Turkey. Natural radiation levels of 18 various, globally-distributed industrial granite samples imported by Turkey, were analyzed using gamma-ray spectrometer. The results are compared with the formerly published findings of granite samples from Turkey. Radioactivity levels of 238U, 232Th, and 40K natural radioactive series elements of the selected 18 specimens were measured, which were from 2.4 ± 0.5 to 88.8 ± 3.6 Bq kg−1 for 238U, from 2.4 ± 0.7 to 273 ± 0.9 Bq kg−1 for 232Th, and from 169 ± 24 to 1,479 ± 94 Bq kg−1 for 40K. Radium equivalent activities (Raeq) were calculated for the granite samples to assess their radiation hazards in the construction of dwellings. The Raeq values of granite samples varied in the range of 39.05–570 Bq kg−1, only one sample exceeded the safe limit value of 370 Bq kg−1 set by the OECD-NEA (Nuclear Energy Agency. Exposure to radiation from natural radioactivity in building materials. Report by NEA Group of Experts 1979). Absorbed dose rates in air were found between 18.74 and 261 nGy h−1 and radiogenic heat production values were calculated in the range of 0.45–6.53 μW m−3. All rock samples used in this study were also analysed mineralogically and defined their compositions.

The environmental characteristics of usage of coal gangue in bricking-making: A case study at Huainan, China

The behaviors of natural radionuclides and toxic elements during coal gangue brick making processes are described. A simulation experiment of coal gangue brick firing was carried out to evaluate the enrichments of natural radionuclides and volatilizations of elements. Simultaneous sampling of coal gangue and corresponding combustion product (slag) was performed. The radioactivities of the radionuclide were determined by high-purity germanium gamma ray spectrometer, and the concentrations of toxic elements were analyzed by ICP-MS. Results have shown that the level of natural radionuclides may not cause immediate or acute environmental impacts because the Raeq values and Hex (in the brick) are 345Bqkg−1 and 0.89, lower than the limit values of 370Bqkg−1 and 1, respectively. However, the Raeq and Hex values are near the limit values, their chronic-environmental and health impacts should be considered noteworthy. The elements found in the emission could be categorized into two types: non-volatilized elements (Co, Cr, Mn and V) and volatilized elements (As, Cd, Cu, Ni, Se, Sn and Zn). Understanding the behaviors of natural radionuclides and toxic elements during brick making processes is helpful for the assessment of their potential impacts to human health and the environment.

Radionuclides measurements and mineralogical studies on beach sands, East Rosetta Estuary, Egypt

Radiometric measurements were carried out for the beach sands from East Rosetta estuary to determine the activity concentrations of 238U, 226Ra, 232Th, and 40K, using a Hyper Pure Germanium spectrometer, to estimate the dose rates and radiation hazard indices. The average specific activities are 778.20 Bq/kg for 238U; 646.89 Bq/kg for 226Ra; 621.92 and 627.85 Bq/kg for the 222Rn daughters 214Pb and 214Bi respectively. The average specific activity of 232Th is 1510.25 Bq/kg, while the calculated specific activity for 40K has an average of 8.41 Bq/kg. The average specific activity of 235U is 38.61 Bq/kg. The average absorbed dose rate is 1211.36 nGy/h, 20 times higher than the estimated average global primordial radiation of 60 nGy/h and 6 times higher than that of the world range (10–200 nGy/h). The radium equivalent (Raeq) values are from 6 to 9 times the recommended value. The internal and external hazard indices (Hint, Hex) indicate that their values are from 6 to 11 times the permissible values of these indices. These higher values may be due to the presence of economic heavy minerals containing radionuclides as zircon and monazite as well as some trace minerals, thorite and uranothorite. The mineralogical study indicates the beach sands contain heavy minerals, zircon, monazite, rutile, ilmenite, leucoxene, magnetite and garnet. The average abundance of zircon is 0.175 wt% ranging from 0.125 wt% to 0.239 wt%, while it is 0.004wt% ranging from 0.001 wt% to 0.007 wt% for monazite. The average abundance is 0.087 wt% for rutile; 2.029 wt% for ilmenite; 1.084 wt% for magnetite; 0.384 wt% for leucoxene and 0.295 wt% for garnet.

Distribution of radionuclides and radiation hazard assessment in soils of Southern Namibia, Southern Africa

The activity concentrations of (238)U, (232)Th and (40)K in soil samples taken from four major towns across southern Namibia have been determined by gamma spectroscopy and used to calculate the mean dose rate, radium equivalent activity (Raeq) and external hazard index (Hex) for each town. The average concentrations of radionuclides in the towns vary from 10.7±3.1 to 35.6±8.4 Bq kg(-1) for (238)U, 12.3±4.9 to 77.8±20.9 Bq kg(-1) for (232)Th and 248.0±35.6 to 734.6±61.4 Bq kg(-1) for (40)K. These values are within the range of concentrations reported in some countries but most of the values for (232)Th and (40)K are above the worldwide averages. However, the mean effective dose rate of 0.08±0.03 mSv y(-1) and the mean values of Raeq and Hex for the region are below their respective permissible limits, thus indicating that radiation hazard is negligible in the region.

Assessment of radioactivity and the associated hazards in local cement types used in Tamilnadu, India

Activity concentration of 232Th, 226Ra and 40K in local cement types has been measured using NaI (Tl) gamma spectrometry. The radium equivalent activity (Raeq) of the samples was calculated and compared with similar data reported in the literature. The comparison has revealed that Raeq values obtained fall far below the criterion limit specified for building materials. The potential radiological hazard of the different samples was estimated using different approaches: representative level index and annual dose limit (dose due to gamma radiation inside the room and inhalation of radon). The estimated representative level index for all the samples is less than unity (the upper limit) indicating that the associated gamma radiation level is low. The annual dose limit falls within 0.167mSv to 0.603mSv, which is an order of magnitude below the criterion limit specified for building materials in the literature.

Evaluation of natural radioactivity levels and radiation hazards of some industrial Egyptian ores

The activity concentration of natural radionuclides (238U, 232Th, and 40K) in three industrial Egyptian ores including manganese ore (M), white sand (W), and dolomite ore (D) collected from Sinai area in Egypt were evaluated. The sample morphology was studied by EDS-XRD and SEM. Radiometric measurements were based on the characteristic spectral peaks of each radionuclide. The observed high activity of 238U confirmed that the natural radioactivity of the ores studied is mainly due to the uranium series. The calculated radium-equivalent activities (Ra-eq) were found to be 6553, 2848, and 431 Bq kg−1 for M, W, and D respectively. For M and W samples, the Ra-eq values are higher than the permissible level recommended in Egypt (1000 Bq kg−1). The annual effective doses were found to be 4.3 ± 0.3, 1.36 ± 0.02, and 0.66 ± 0.01 mSv year−1, respectively. The recorded data of the radioactivity background levels in the industrial samples studied can be used as reference values not only to assess the anthropogenic activities in the environment, but also to explain the metamorphic cycles of these radionuclides due to geological processes.

Assessment of Natural Radioactivity and Radiological Hazards in Building Materials Used in Yan’an, China

The concentration of natural radionuclides in commonly used building materials collected from Yan'an, China, was determined using gamma ray spectroscopy with a NaI(Tl) detector. The activity concentration of ²²⁶Ra, ²³²Th, and ⁴⁰K in the studied building materials ranges from 9.4-73.1, 11.5-86.9, and 258.9-1,055.1 Bq kg⁻¹, respectively. The concentrations for these natural radionuclides were compared with the reported data of other countries and the world mean values for soil. The radium equivalent activity (Raeq), external hazard index (Hex), internal hazard index (Hin), indoor air absorbed dose rate, and annual effective dose rate due to natural radionuclides in samples were estimated to assess radiological hazards for people living in dwellings made of the studied building materials. The calculated Raeq values of all building materials (75.7-222.1 Bq kg⁻¹) are lower than the limit of 370 Bq kg⁻¹. The values of Hex and Hin are less than unity. The mean values of indoor air absorbed dose rates of all building materials (101.0 ± 14.1-177.0 ± 6.8 nGy h⁻¹) are higher than the world population-weighted average of 84 nGy h⁻¹, while the mean values of annual effective dose range from 0.50 ± 0.07-0.87 ± 0.03 mSv y⁻¹, which are lower than the recommended limit of 1 mSv y⁻¹. It is found that these materials may be used safely as construction materials and do not pose significant radiation hazards to inhabitants.

Natural radioactivity in different commercial ceramic samples used in Yemeni buildings

In this work we calculated the radioactivity concentrations of the natural radioactive nuclides 238U, 232Th, 226Ra and 40K for 10 commercial samples collected from 10 different companies which are used in the construction of Yemeni buildings. Gamma ray spectroscopy was used to analyze the samples and the concentrations of radioisotopes were determined using a hyper-pure germanium (HPGe) detector in Bq/kg dry-weight. The average concentrations of 238U, 232Th, 226Ra and 40K were found to be 131.4, 83.55, 131.88 and 400.7Bq/kg respectively. Different hazard indices were also determined. The results showed that the average radium equivalent activity (Raeq), the absorbed dose rate (Dr), the annual effective dose equivalent (AEDE), the external hazard index (Hex) and representation level index (Iγ) were: 307.52Bq/kg, 139.31nGy/h, 1.40mSv/yr, 0.83 and 2.15 respectively. The mean value of (Raeq) obtained in this study is in good agreement with that of the international value while the mean values of the other indices are found to be higher than the international reference values. The measured activity concentrations for these radionuclide were compared with the reported data obtained from similar materials used in other countries.

Measurement of natural radioactivity in building materials used in Urumqi, China

Building materials contain natural radionuclides (226)Ra, (232)Th and (40)K, which cause direct radiation exposure of the public. The concentrations of (226)Ra, (232)Th and (40)K in commonly used building materials of Urumqi, China have been analysed using gamma-ray spectrometry. The concentrations of (226)Ra, (40)K and (232)Th in the studied building materials range from 19.8 to 87.4, from 273.3 to 981.2 and from 11.6 to 47.7 Bq kg(-1), respectively. The radium equivalent activity (Raeq), gamma index (Iγ) and alpha index (Iα) were calculated to assess the radiation hazards to people living in dwellings made of the materials studied. The calculated Raeq values of all the building materials are lower than the limit of 370 Bq kg(-1) for building materials. The values of Iγ and Iα of all the building materials are less than unity. The study shows that these materials may be safely used as construction materials and do not pose significant radiation hazards.