The processing of amang, or tin tailings, for valuable minerals has been shown to technologically enhance NORM and this has stirred significant radiological safety and health concerns among Malaysia's regulatory authority. A growing radiological concern is now focused on the amang effluent containing NORM in recycling ponds, since these ponds may be reclaimed for future residential developments. A study was carried out to assess the radiological risk associated with amang processing and the accumulated effluent in the recycling ponds. Twenty-six sediment samples from the recycling ponds of two amang plants in the states of Selangor and Perak, Malaysia, were collected and analyzed. The maximum activity concentrations of (238)U, (226)Ra, (232)Th and (40)K recorded in sediments from these ponds were higher than Malaysia's and the world's natural highest. Correspondingly, the mean radium equivalent activity concentration indices, Ra(eq), and gamma radiation representative level index, I(gammar), were higher than the world's average. The enhancement of NORM in effluent sediments as a consequence of amang processing, and the use of a closed water management recycling system created Effective Dose Rates, E (nSv h(-1)), that signal potential environmental radiological risks in these ponds, should they be reclaimed for future land use.
The Jos Plateau has been reported to have elevated levels of natural background radiation. A few earlier studies have measured the levels of natural radioactivity for specific locations in the area. Our interest is to investigate how geology of the study area influences the activity concentrations of natural radionuclides. Thus, the activity concentrations of terrestrial radionuclides in soil samples collected across the geological formations of the Jos Plateau were determined by gamma spectrometry technique. The mean activity concentrations of 226Ra, 232Th and 40K were found to exceed their corresponding world reference values of 35, 40 and 400 Bq kg-1, respectively. Data were compared using statistical methods, analysis of variance (ANOVA) and post hoc tests. The results revealed in some instances significant influences of geological types on the activity concentrations in the area. The spatial distribution maps of activity concentrations of 226Ra, 232Th and 40K were geostatistically interpolated by ordinary Kriging method using ArcGIS software.
The concentrations of primordial radionuclides (226Ra, 232Th and 40K) in commonly used building materials (brick, cement and sand), the raw materials of cement and the by-products of coal-fired power plants (fly ash) collected from various manufacturers and suppliers in Bangladesh were determined via gamma-ray spectrometry using an HPGe detector. The results showed that the mean concentrations of 226Ra, 232Th and 40K in all studied samples slightly exceeded the typical world average values of 50 Bq kg(-1), 50 Bq kg(-1) and 500 Bq kg(-1), respectively. The activity concentrations (especially 226Ra) of fly-ash-containing cement in this study were found to be higher than those of fly-ash-free cement. To evaluate the potential radiological risk to individuals associated with these building materials, various radiological hazard indicators were calculated. The radium equivalent activity values for all samples were found to be lower than the recommended limit for building materials of 370 Bq kg(-1), with the exception of the fly ash. For most samples, the values of the alpha index and the radiological hazard (external and internal) indices were found to be within the safe limit of 1. The mean indoor absorbed dose rate was observed to be higher than the population-weighted world average of 84 nGy h(-1), and the corresponding annual effective dose for most samples fell below the recommended upper dose limit of 1 mSv y(-1). For all investigated materials, the values of the gamma index were found to be greater than 0.5 but less than 1, indicating that the gamma dose contribution from the studied building materials exceeds the exemption dose criterion of 0.3 mSv y(-1) but complies with the upper dose principle of 1 mSv y(-1).
An extensive study was conducted to determine the activity concentrations of natural and artificial radionuclides 226Ra, 232Th, 40K, and 137Cs in soil samples of each governate of Jordan. A total of 370 samples have been measured using a high-purity germanium detector. The activity concentration for 226Ra, 232Th, 40K, and 137Cs has mean values of 42 ± 3, 23 ± 3, 309 ± 21, and 3.7 ± 0.9 Bq kg-1, respectively. The highest mean activity concentration for 226Ra was found to be 138 ± 4 Bq kg-1 in the Alkarak governate. In the Ajloun and Jarash governates, the highest mean activity concentration was 35 ± 3 Bq kg-1 for 232Th, and 14.2 ± 1.9 Bq kg-1 for 137Cs, respectively. Geological influence on the activity concentrations was investigated using the one-way analysis of variance (ANOVA) and independent samples. The ANOVA results indicate that there are strong significant differences between the activity concentrations of 232Th, 40K, and 137Cs based on geological formations the radionuclides occur. The main contribution to gamma dose rate was due to 226Ra activity concentration. Radium equivalent and external hazard index are associated with a mean value of 98 Bq kg-1, and 0.266, respectively.
Extensive environmental survey and measurements of gamma radioactivity in the soil samples collected from Segamat District were conducted. Two gamma detectors were used for the measurements of background radiation in the area and the results were used in the computation of the mean external radiation dose rate and mean weighted dose rate, which are 276 nGy h(-1) and 1.169 mSv y(-1), respectively. A high purity germanium (HPGe) detector was used in the assessment of activity concentrations of (232)Th, (226)Ra and (40)K. The results of the gamma spectrometry range from 11 ± 1 to 1210 ± 41 Bq kg(-1) for (232)Th, 12 ± 1 to 968 ± 27 Bq kg(-1) for (226)Ra, and 12 ± 2 to 2450 ± 86 Bq kg(-1) for (40)K. Gross alpha and gross beta activity concentrations range from 170 ± 50 to 4360 ± 170 Bq kg(-1) and 70 ± 20 to 4690 ± 90 Bq kg(-1), respectively. These results were used in the plotting of digital maps (using ARCGIS 9.3) for isodose. The results are compared with values giving in UNSCEAR 2000.
Malaysia, a rapidly growing industrial country, is susceptible to pollution via large-scale industrial engagements and associated human activities. One particular concern is the potential impact upon the quality of locally resourced vegetables, foodstuffs that contain important nutrients necessary for good health, forming an essential part of the Malaysian diet. As a part of this, it is of importance for there to be accurate knowledge of radioactive material uptake in these vegetables, not least in respect of any public health detriment. Herein, using HPGe γ-ray spectrometry, quantification has been performed of naturally occurring radionuclides in common edible vegetables and their associated soils. From samples analyses, the soil activity concentration ranges (in units of Bq/kg) for (226)Ra, (232)Th and (40)K were respectively 1.33-30.90, 0.48-26.80, 7.99-136.5 while in vegetable samples the ranges were 0.64-3.80, 0.21-6.91, 85.53-463.8. Using the corresponding activities, the transfer factors (TFs) from soil-to-vegetables were estimated, the transfers being greatest for (40)K, an expected outcome given the essentiality of this element in support of vigorous growth. The TFs of (226)Ra and (232)Th were found to be in accord with available literature data, the values indicating the mobility of these radionuclides to be low in the studied soils. Committed effective dose and the associated life-time cancer risk was estimated, being found to be below the permissible limit proposed by UNSCEAR. Results for the studied media show that the prevalent activities and mobilities pose no significant threat to human health, the edible vegetables being safe for consumption.
Concentrations of primordial radionuclides in common construction materials collected from the south-west coastal region of India were determined using a high-purity germanium gamma-ray spectrometer. Average specific activities (Bq kg(-1)) for (238)U((226)Ra) in cement, brick, soil and stone samples were obtained as 54 ± 13, 21 ± 4, 50 ± 12 and 46 ± 8, respectively. Respective values of (232)Th were obtained as 65 ± 10, 21 ± 3, 58 ± 10 and 57 ± 12. Concentrations of (40)K radionuclide in cement, brick, soil and stone samples were found to be 440 ± 91, 290 ± 20, 380 ± 61 and 432 ± 64, respectively. To evaluate the radiological hazards, radium equivalent activity, various hazard indices, absorbed dose rate and annual effective dose have been calculated, and compared with the literature values. Obtained data could be used as reference information to assess any radiological contamination due to construction materials in future.
Understanding the public awareness concerning the Lynas Advanced Material Plant (LAMP), an Australian rare earths processing plant located in Malaysia, a radiological study in soil and water samples collected at random surrounding the LAMP environment was undertaken using HPGe gamma-ray spectrometry. The mean soil activities for (226)Ra, (232)Th, and (40)K were found to be 6.56 ± 0.20, 10.62 ± 0.42, and 41.02 ± 0.67 Bq/kg, respectively, while for water samples were 0.33 ± 0.05, 0.18 ± 0.04, and 4.72 ± 0.29 Bq/l, respectively. The studied areas show typical local level of radioactivity from natural background radiation. The mean gamma absorbed dose rate in soils at 1 m above the ground was found to be 11.16 nGy/h. Assuming a 20 % outdoor occupancy factor, the corresponding annual effective dose showed a mean value of 0.014 mSv year(-1), significantly lower than the worldwide average value of 0.07 mSv year(-1) for the annual outdoor effective dose as reported by UNSCEAR (2000). Some other representative radiation indices such as activity utilization index (AUI), H ex, H in, excess lifetime cancer risk (ELCR), and annual gonadal dose equivalent (AGDE) were derived and also compared with the world average values. Statistical analysis performed on the obtained data showed a strong positive correlation between the radiological variables and (226)Ra and (232)Th.
The presence of natural radioactivity and (137)Cs has been investigated in fresh media obtained from South China Sea locations off the coast of peninsular Malaysia. The media include seafood, sea water and sediment. The samples were collected some weeks prior to the devastating 2011 Tōhoku earthquake and associated tsunami, the occurrence of which precipitated the Fukushima incident. All samples showed the presence of naturally occurring (226)Ra, (228)Ra and primordial (40)K, all at typically prevailing levels. The concentrations of natural radioactivity in molluscs were found to be greater than that of other marine life studied herein, the total activity ranging from 337 to 393 Bq kg(-1) dry weight. The total activity in sea water ranged from 15 to 88 Bq l(-1). Sediment samples obtained at deep sea locations more than 20 km offshore further revealed the presence of (137)Cs. The activity of (137)Cs varied from ND to 0.5 Bq kg(-1) dry weight, the activity increasing with offshore distance and depth. The activity concentrations presented herein should be considered useful in assessing the impact of any future radiological contamination to the marine environment.
Batu Dam is of considerable importance to the metropolis of Kuala Lumpur, its existence and the quality assessment of its waters being essential in helping to maintain the lives of a large sector of the Malaysian population. Concerning the level of naturally occurring radioactivity contained within its waters, a well characterised HPGe γ-ray technique has been used in making measurements of the concentrations of primordial radionuclides in samples of surface water from the Dam. Based on the mean individual daily consumption of dam water, estimation has been made of the concomitant radiation dose. Activity concentrations, in units of Bq l-1, have been found to be in the range 2.4-3.2 for 226Ra, 1.1-1.3 for 232Th and 22.7-40.7 for 40K, in line with literature data for surface waters. The total annual ingestion dose for infants (<1 y) and adolescents (12-17 y) are found to be significant and greater than the World Health Organization recommended maximum dose of 0.1 mSv y-1 from the imbibing of drinking water. However, the Dam water does not pose a threat to public health, the Dam water not being used as the sole source of drinking water. Noting that this is the only known study of water from Batu Dam, the reported levels allow for evaluation of future changes in the natural radioactivity profile.
Activity concentrations of primordial radionuclides in sand samples collected from the coastal beaches surrounding Penang Island have been measured using conventional γ-ray spectrometry, while in-situ γ-ray doses have been measured through use of a portable radiation survey meter. The mean activity concentrations for 226Ra, 232Th and 40K at different locations were found to be less than the world average values, while the Miami Bay values for 226Ra and 232Th were found to be greater, at 1023±47 and 2086±96Bqkg̶ 1 respectively. The main contributor to radionuclide enrichment in Miami Bay is the presence of monazite-rich black sands. The measured data were compared against literature values and also recommended limits set by the relevant international bodies. With the exception of Miami Bay, considered an elevated background radiation area that would benefit from regular monitoring, Penang island beach sands typically pose no significant radiological risk to the local populace and tourists visiting the leisure beaches.
The presence of natural radionuclides in the food chain point to a need to assess concentration levels and concomitant radiological risk. Highly popular and forming a staple part of the diet in North Africa, the Arabian Peninsula, and West Asia, palm dates growing naturally there have even greater marketability than simple satisfaction of domestic demand, the palm dates representing a valuable export item. Accurate knowledge of the levels of natural radioactivity in the fruit is thus of importance. In this study, using high-purity germanium gamma-ray spectrometry, quantification has been made of natural radionuclide concentrations in imported dates originating from Iran, Saudi Arabia, and Tunisia. Sample analyses reveal respective mean activity concentrations of 1.4 ± 0.3, 0.8 ± 0.4, and 186 ± 9 Bq kg dry weight for Ra, Ra, and K. For each nuclide, the mean concentration varies little between the dates of the three represented regions. The estimated committed effective dose resulting from the consumption of date fruits for a typical adult was found to be 29.9 μSv y, well below the global internal dose of 290 μSv y assessed by the United Nations Scientific Committee on the Effects of Atomic Radiation to be due to food and water intake. Similarly, the excess lifetime cancer risk due to naturally occurring radioactive material exposure via date fruit consumption is seen to be below the International Commission on Radiological Protection cancer risk factor of 2.5 × 10 based on the additional annual dose limit of 1 mSv for a member of the general public. The results show no significant uptake in the analyzed date fruits.
A particular category of jewelry is one involving bracelets and necklaces that are deliberately made to contain naturally occurring radioactive material (NORM)-purveyors making unsubstantiated claims for health benefits from the release of negative ions. Conversely, within the bounds of the linear no-threshold model, long-term use presents a radiological risk to wearers. Evaluation is conducted herein of the radiological risk arising from wearing these products and gamma-ray spectrometry is used to determine the radioactivity levels and annual effective dose of 15 commercially available bracelets (samples B1 to B15) and five necklaces (samples N16 to N20). Various use scenarios are considered; a Geant4 Monte Carlo (Geant4 MC) simulation is also performed to validate the experimental results. The dose conversion coefficient for external radiation and skin equivalent doses were also evaluated. Among the necklaces, sample N16 showed the greatest levels of radioactivity, at 246 ± 35, 1682 ± 118, and 221 ± 40 Bq, for 238U, 232Th, and 40K, respectively. For the bracelets, for 238U and 232Th, sample B15 displayed the greatest level of radioactivity, at 146 ± 21 and 980 ± 71 Bq, respectively. N16 offered the greatest percentage concentrations of U and Th, with means of 0.073 ± 0.0002% and 1.51 ± 0.0015%, respectively, giving rise to an estimated annual effective dose exposure of 1.22 mSv, substantially in excess of the ICRP recommended limit of 1 mSv/year.
Building materials of different brands were assessed for the concentrations of 226Ra, 232Th and 40K using HPGe detector. The activity concentrations in the measured samples ranged from 27 ± 8 to 82 ± 8 Bq kg-1 for 226Ra, 41 ± 4 to 101 ± 8 Bq kg-1 for 232Th and 140 ± 8 to 940 ± 19 Bq kg-1 for 40K, respectively. The Radium equivalent (Raeq) activity from the samples was found to be <370 Bq kg-1 as the recommended value for construction materials. This study will set a baseline data for significant standards on radiation exposure of the measured radionuclides in the selected building materials used in Nigeria.
Proper documentation of baseline radiation data of different environments is an important step toward adequate environmental monitoring, and it provides quick means to quantitatively check and determine possible radionuclide contamination by anthropogenic sources. Besides, such documentation is useful for decision making processes, assessment of dose rates to the public, epidemiological studies, and environmental regulations. This review summarizes the results of studies conducted on radioactivity in Nigerian environments. For most soil samples, the levels of radioactivity are well within the world averages of 33, 45, and 420 Bq kg-1 for 226Ra, 232Th and 40K, respectively. Other soil samples from regions such as Abeokuta in the southwest, and Jos in the northcentral have been described as high background radiation areas with radioactivity values comparable with those obtained from known high background radiation areas such as the Odisha (formerly Orissa) coast in India (with values reported as 350, 2,825, and 180 Bq kg-1 for 238U/226Ra, 232Th, and 40K, respectively). In some parts of Nigeria, surface and underground water sources used for drinking and other purposes also present elevated levels of 226Ra above the world range of 0.01 to 0.1 Bq l-1 and the tolerable levels recommended by the World Health Organization and U.S. Environmental Protection Agency. Corresponding radiation doses due to measured radioactivities from different environments were estimated and compared with those reported in similar studies around the world. More so, the human and environmental health hazards that might be associated with the reported radioactivity in different environmental settings are discussed. The present report is expected to support authorities in developing appropriate regulations to protect the public from radiation exposure arising from environmental radioactivity. The report also examines other areas of consideration for future studies to ensure adequate radiation monitoring in Nigeria.
The radioactivity quantity and quality were determined in soil and water samples in Northern Malaysian Peninsula (NMP) using HPGe spectroscopy and GR-135 spectrometer. The (226)Ra, (232)Th and (40)K concentrations in soil samples are 57±2, 68±4 and 427±17 Bq kg(-1), respectively, whereas in water samples were found to be 2.86±0.79, 3.78±1.73 and 152±12 Bq l(-1), respectively. These concentrations are within those reported from literature in other countries in the world. The radiological hazard indices of the samples were also calculated. The mean values obtained from soil samples are 186 Bq kg(-1), 88 nGy h(-1), 108 μSv y(-1), 0.50 and 0.65 for Radium Equivalent Activity (Ra(eq)), Absorbed Dose Rates (D(R)), Annual Effective Dose Rates (ED), External Hazard Index (H(ex)) and Internal Hazard Index (H(in)) respectively, whereas, for water samples were found to be 20, 10, 13, 0.05 and 0.06, respectively. All the health hazard indices are well below their recommended limits, except in two soil sampling sites which were found to be (*)025 (1.1 H(ex)) and (*)026 (1.1 H(ex), 1.6 H(in)). The calculated and the measured gamma dose rates had a good correlation coefficient, R=0.88. Moreover, the average value radon is 20 (in the range of 7-64) Bq m(-3), a positive correlation (R=0.81) was observed between the (222)Rn and (226)Ra concentrations in samples measured by the SNC continuous radon monitor (model 1029, Sun Nuclear Corporation) and HPGe detector, respectively. Some soils in this study with H(in) and H(ex)<1 are suitable for use in agriculture and as building materials. Also, in this study H(in) and H(ex)<1 for water samples, therefore, water after processing and filtration is safe and suitable for use in household and industrial purposes.
Tapioca and sweet potato are the fourth and fifth most consumed crops in Malaysia. The activity concentrations of natural radionuclides in these vegetables were assessed from two regions in Malaysia (Kedah and Penang) along with soil samples using gamma ray spectroscopy. The transfer factors of 226Ra, 232Th and 40K from soil to vegetables were calculated, and a dose assessment was performed. The activity concentrations of 226Ra, 232Th and 40K in soil samples did not show a significant variation with the regions investigated, and the average values obtained, in Bq/kg, (±SD) were as follows: 80 ± 41, 56 ± 12, 516 ± 119, respectively. The respective average activity concentrations in vegetables were as follows, in Bq/kg: (±SD) 2.0 ± 0.5, 6 ± 2, 153 ± 49. The corresponding transfer factors were calculated to be 0.03, 0.11 and 0.31 for 226Ra, 232Th and 40K, respectively. The average annual effective doses due to the exposure from soil and ingestion of vegetables were found to lie within the worldwide ranges.