Population dose distribution due to soil radioactivity concentration levels in 18 cities across Nigeria.

The natural radioactivity concentrations in soil samples collected from 186 locations across 18 cities in the six geo-political zones of Nigeria have been determined using gamma-ray spectrometry. Results show that the concentrations of (40)K, (238)U and (232)Th in the soil samples varied from below detection limits (BDL) to 1459.4 Bq kg(-1) with a mean of 73.3 +/- 18.5 Bq kg(-1) for (40)K, whereas for (238)U and (232)Th values varied from 9.2 to 113.7 Bq kg(-1) with a mean of 33.9 +/- 7.4 Bq kg(-1) and from BDL to 175.7 Bq kg(-1) with a mean of 12.4 +/- 3.1 Bq kg(-1), respectively. The average gamma absorbed dose rate in air across the cities ranged between 19 +/- 5 and 88 +/- 44 nGy h(-1) and the gross mean was 42.0 +/- 21.0 nGy h(-1). Using available population data in the study areas, about 2.84% of the population is exposed to a radiation dose rate of less than 20 nGy h(-1), 52.40% to a radiation dose rate between 20 and 30 nGy h(-1), 31% to a radiation dose rate between 30 and 60 nGy h(-1) and about 13.76% to dose rates greater than 60 nGy h(-1).     

Assessment of radioactivity and radon exhalation rate in Egyptian cement

The cement industry is considered as one of the basic industries that plays an important role in the national economy of developing countries. Activity concentration of 238U, 232Th, and 40K in local cement types from different Egyptian factories has been measured using a shielded HPGe detector. The average values obtained for 238U, 232Th, and 40K activity concentrations in different types of cement are lower than the corresponding global values reported in UNSCEAR publications. On the basis of the hazard index and the radium equivalent concentration, it can be shown that the natural radioactivity of cement samples is not greater than the values permitted in the established standards in other countries. A solid-state nuclear track detector SSNTD (Cr-39) was used to measure the radon concentration as well as exhalation rate for these samples. The effective radium content and the exhalation rate are found to vary from 12.75 to 38.52 Bq kg(-1) and 61.19 to 181.39 Bq m(-2) d(-1), respectively.     

Measurement of activity concentrations of natural radionuclides in the topsoil of IITA Ibadan by gamma-ray spectrometry.

The activity concentrations of the natural radionuclides in the soils at the International Institute of Tropical Agriculture, (IITA), Idi-Ose, Moniya, Ibadan, Nigeria were investigated using a NaI (Tl) scintillation detector coupled with a Canberra series 10 plus multichannel analyser as the detecting device for gamma scintillation spectroscopy. The whole area was divided into grids and soil samples were collected from the points of intersection of the grids. The average activity concentrations obtained for the three radionuclides (40K, 238U and 232Th) were 180.08 +/- 90.54 Bq kg(-1) for 40K, 8.901 +/- 5.063 Bq kg(-1) for 238U and 11.01 +/- 7.686 Bq kg(-1) for 232Th. The average values of the absorbed dose rate for each radionuclide were found to be 7.33 nGy h(-1) for 232Th, 7.55 nGy h(-1) for 40K and 3.82 nGy h(-1) for 238U. The average (baseline) of the total absorbed dose rate was found to be 18.72 +/- 8.11 nGy h(-1). The baseline average outdoor annual effective dose equivalent at IITA due to the concentrations of the radionuclides was found to be 22.95 +/- 9.94 microSv y(-1). This value is low compared to the world average of 70 microSv y(-1) specified by UNSCEAR for an outdoor effective dose. Hence the probability of occurrence of any of the health effects of radiation is low.     

Radioactivity levels of staple foodstuffs and dose estimates for most of the Tanzanian population.

Levels of natural radioactivity in staple food products (maize and rice) from various localities of Tanzania have been studied. The average activity concentrations of 40K, 232Th and 238U in maize were 48.79 +/- 0.11, 4.08 +/- 0.01 and 13.23 +/- 0.10 Bq kg(-1), respectively. In rice the concentrations of 40K, 232Th and 238U were 24.67 +/- 0.03, 3.82 +/- 0.02 and 5.02 +/- 0.02 Bq kg(-1), respectively. 137Cs was detected in only one sample collected in Zanzibar. The sample, with activity concentration of 5.57 +/- 0.01 Bq kg(-1), had been imported from Thailand. The relatively high average concentrations of the radionuclides in maize compared to rice may be attributed to the extensive use of phosphate fertilizers in maize production in Tanzania. Total annual committed effective doses due to total 232Th and 238U intakes as a result of consumption of staple foodstuffs for infants, children and adults were 0.16, 0.29 and 0.36 mSv y(-1), respectively, which are lower than the annual dose guideline for the general public.     

Assessment of the natural radioactivity and its radiological hazards in Shewa-Shahbaz Garhi igneous complex, Peshawar Plain, NW Pakistan.

Forty-two representative rock samples used for construction purpose were collected from the quarries and outcrops of the rock units forming the Shewa-Shahbaz Garhi igneous complex, North-West Pakistan. Radioactivity of terrestrial radionuclides (238U, 232Th, and 40K) was measured in these samples using gamma ray spectrometry system with an HPGe detector. The samples showed fairly high mean concentrations of 51 +/- 16 Bq kg(-1) of 238U, 70 +/- 20 Bq kg(-1) of 232Th and 1,272 +/- 367 Bq kg(-1) of 40K. Mean absorbed gamma dose rate in air of 119 +/- 29 nGy h(-1) was found. Assessment of radiological hazards was made by calculating radium equivalent activities with external and internal hazard indices. The calculations showed radium equivalent activity ranging from 52 to 346 Bq kg(-1). External and internal hazard indices ranging from 0.14 to 0.94 and 0.17 to 1.1, respectively, were found.     

Radium-226, 232Th, and 40K distribution in the environment of Kaiga of south west coast of India

Systematic studies on gamma radiation level and the distribution of natural radionuclides were carried out under a pre-operational survey for the establishment of baseline data on background radiation level and the distribution of radio-nuclides in the environment of Kaiga, in the south west coast of India, where a nuclear power reactor of 235 MWe has just been commissioned. The external gamma absorbed dose rates prevailing in the region were measured using a portable plastic scintillometer. Soil samples from 18 stations were collected from depth intervals of 0-5, 5-10, and 10-25 cm and analyzed for their 226Ra, 232Th, and 40K activity concentrations by gamma spectrometry employing a 90 cc PGT HpGe detector coupled to an EG&G ORTEC 8K multichannel analyzer. The activity of 226Ra was found to vary between 15.5-61.2 Bq kg(-1) with a mean value of 31.3 Bq kg(-1), that of 232Th varies between 11.4-41.9 Bq kg(-1) with a mean value of 27.5 Bq kg(-1) and of 40K between 78.3-254.8 Bq kg(-1) with a mean value of 159.9 Bq kg(-1) in 0-5 cm soil profiles of the region. The contributions of 238U, 232Th, and 40K to the total gamma absorbed dose rate were 39.9%, 40.7%, and 16.0%, respectively. The gamma absorbed dose rate in air estimated using the results of activity concentration of 226Ra, 232Th, and 40K are found to compare well with that of the direct measurement. The results of the study were compared with the literature values reported for other environs of the country as well as the world, and conclusions are drawn.     

Distribution of natural radioactivity in rocks from Ikogosi-Ekiti, Southwestern Nigeria and its radiological implications

The natural radioactivity in some rock samples in Ikogosi-Ekiti, Southwestern Nigeria, has been measured using a very sensitive gamma spectroscopic system consisting of a 76 mm x 76 mm NaI(TI) scintillation detector system coupled to a versatile Canberra Series 10 plus multichannel analyzer. The average concentrations of natural radioisotopes 238U, 232Th, and 40K are 57.9 +/- 28.1 Bq kg-1, 81.6 +/- 23.8 Bq kg(-1) and 1203.1 +/- 687.2 Bq kg(-1), respectively. These average values give rise to a mean absorbed dose rate of 0.128 +/- 0.051, microGy h(-1) at a height of 1.0 m and an effective dose equivalent of 156.90 microSv (y-1). The results indicate no radiological anomaly. The data presented here will serve as a baseline survey for primordial radionuclide concentrations in rocks of the area.     

Elemental analysis of Egyptian phosphate fertilizer components

The accumulation of certain elements in vitally important media such as water, soil, and food is undesirable from the medical point of view. It is clear that the fertilizers vary widely in their heavy metals and uranium content. A shielded high purity germanium HPGe detector has been used to measure the natural concentration of 238U, 232Th, and 40K activities in the phosphate fertilizer and its components collected from Abu-Zaabal fertilizers and chemical industries in Egypt. The concentration ranges were 134.97-681.11 Bq kg(-1), 125.23-239.26 Bq kg(-1), and 446.11-882.45 Bq kg(-1) for 238U, 232Th, and 40K, respectively. The absorbed dose rate and external hazard index were found to be from 177.14 to 445.90 nGy h(-1) and 1.03 to 2.71 nGy y(-1), respectively. The concentrations of 22 elements (Be, Na, Mg, Si, P, S, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sr, Zr, Mo, Cd, Ba) in the samples under investigation were determined by inductively coupled plasma optical-emission spectrometry (ICP-OES). The results for the input raw materials (rock phosphate, limestone and sulfur) and the output product as final fertilizer are presented and discussed.     

(226)Ra, (232)Th and (40)K contents in soil samples from Garhwal Himalaya, India, and its radiological implications

The exposure of human beings to ionising radiation from natural sources is a continuing and inescapable feature of life on earth. Natural radionuclides are widely distributed in various geological formations and ecosystems such as rocks, soil groundwater and foodstuffs. In the present study, the distribution of (226)Ra, (232)Th and (40)K was measured in soil samples collected from different lithological units of the Thauldhar and Budhakedar regions of Garhwal Himalaya, India. The collected soil samples were analysed using gamma ray spectrometry. The activity concentrations of the naturally occurring radionuclides (226)Ra, (232)Th and (40)K in these soil samples were found to vary from below detection level (BDL) to 131 +/- 18 Bq kg(-1), 9 +/- 6 to 384 +/- 53 Bq kg(-1) and 471 +/- 96 to 1406 +/- 175 Bq kg(-1), respectively. The distribution of radionuclides depends upon the rock formation and chemical properties within the earth. The activity concentrations vary widely depending on the sample origin. The external absorbed gamma dose rates due to (226)Ra, (232)Th and (40)K were found to vary from 49 to 306 nGy h(-1). The average radium equivalent activity from these soil samples was 300 Bq kg(-1).     

Radioactivity concentrations and dose assessment for soil samples around nuclear power plant IV in Taiwan

Activity concentrations and distributions of natural and man-made radionuclides in soil samples collected around nuclear power plant IV, Taiwan, were investigated for five years to assess the environmental radioactivity and characterisation of radiological hazard prior to commercial operation. The activity concentrations of radionuclides were determined via gamma-ray spectrometry using an HPGe detector. Data obtained show that the average concentrations of the (238)U and (232)Th series, and (40)K, were within world median ranges in the UNSCEAR report. The (137)Cs ranged from 2.46 +/- 0.55 to 12.13 +/- 1.31 Bq kg(-1). The terrestrial absorbed dose rate estimated by soil activity and directly measured with a thermoluminescence dosemeter (excluding cosmic rays), and the annual effective doses, were 45.63, 57.34 nGy h(-1) and 57.19 microSv, respectively. Experimental results were compared with international recommended values. Since the soil in this area is an important building material, the mean radium equivalent activity, external and inhalation hazard indices and the representative level index using various models given in the literature for the study area were 98.18 Bq kg(-1), 0.27, 0.34 and 0.73, respectively, which were below the recommended limits. Analytical results demonstrate that no radiological anomaly exists. The baseline data will prove useful and important in estimating the collective dose near the new nuclear power plant under construction in Taiwan.     

Evaluation of annual committed effective doses to members of the public in Morocco due to 238U and 232Th in various food materials.

Uranium (238U) and thorium (232Th) concentrations were measured in different foods widely consumed in Morocco by using CR-39 and LR-115 type II solid state nuclear track detectors (SSNTDs). Annual committed effective doses due to 238U and 232Th intakes from the ingestion of the studied food materials were evaluated for different age groups of individuals, using the ICRP ingestion dose coefficients. The influence of the 238U and 232Th intakes and ages of individuals on the committed effective dose was investigated. Total annual intakes of 238U and 232Th for a typical food basket for adult members of the Moroccan population were estimated to be 451 +/- 27 Bq y(-1) and 359 +/- 20 Bq y(-1), corresponding to committed effective doses of (20 +/- 1) x 10(-6) Sv y(-1) and (83 +/- 5) x 10(-6) Sv y(-1), respectively.     

An evaluation of radiation and dust hazards at a mineral sand processing plant

This three-part article discusses the results of a 2-y study on radiation and dust hazards in a mineral sand processing plant involving: (1) evaluation of external gamma radiation levels and determination of isotopic composition of the different sand products; (2) evaluation of radiation carried in long-lived radioactive dust (LLRD) particles; (3) evaluation of Rn gas concentrations within the working environs of the plant. Gamma radiation levels had a mean value of approximately 40 nSv h-1, and monazite sand returned the highest activity concentrations of 0.16% and 3.4% for 238U and 232Th, respectively. Low volume gross respirable dust sampling revealed an average long-lived airborne alpha activity concentration of 0.07 +/- 0.02 Bq m-3 and an average dust mass concentration of 3.3 +/- 2 mg m-3. Gamma spectroscopy applied to high-volume air samples showed average airborne 232Th and 238U activities of 0.012 +/- 0.004 Bq m-3 and 0.005 +/- 0.002 Bq m-3, respectively, giving an airborne 232Th: 238U ratio of 2.4:1. Air sampling using a high volume, five-stage cascade impactor indicated an average activity median aerodynamic diameter (AMAD) of 3.2 microns with an associated average geometric standard deviation (GSD) of 2.8. Average radiation dose arising from the inhalation of LLRD was estimated to be 7 mSv per annum. CR-39 (polycarbonate plastic) nuclear track detectors indicated that Rn gas concentrations in the environs of the processing plant dry mill and main product warehouse ranged from 30 Bq m-3 to 220 Bq m-3, with an average value of 100 Bq m-3, which presents a possible inhaled dose from Rn daughters of 1.5 mSv y-1 (assuming an equilibrium ratio of 0.5).     

东北地区土壤中放射性核素含量的抽样测量与分析

目的 测量东北地区土壤中放射性核素含量,从当地气候、成土母岩分布、植被分布、受放射性污染的程度等角度研究不同区域土壤中放射性核素含量存在差异的原因,并评估其对地表γ辐射量的贡献。方法 应用北京核仪器厂生产的BH 1936型低本底多道γ谱仪对由中国计量科学研究院提供的混合体标准源进行测量,得到探测器对²³²Th、²²⁶Ra、²³⁸U和⁴⁰K四种核素所发出的最大γ分支比的全能峰探测效率。测量土壤样品的γ能谱,分析计算得到土壤样品中的放射性核素的含量。结果 通过对东北地区不同区域26份常见土壤样品中天然放射性核素的放射性活度进行抽样测量与数据处理,得出土壤中²³²Th、²²⁶Ra、²³⁸U和⁴⁰K的含量均值分别为:52.9 Bq/kg,44.8 Bq/kg,50.3 Bq/kg,820.3 Bq/kg,较以往年所得数值略有增加。结论 结果表明,²³²Th含量在残积母质类土壤中最高,在沉积母质类土壤中最低;²²⁶Ra和²³⁸U含量在冲积母质类土壤中最高,在残积母质类土壤中最低;⁴⁰K含量在沉积母质类土壤中最高,在冲积母质类土壤中最低。²³²Th和⁴⁰K含量在山地中最高,在平原中最低,而²²⁶Ra和²³⁸U含量则是在平原中最高,在山地中最低。根据土壤中放射性核素含量估算东北地区的年有效环境剂量(0.54 mSv),其值符合正常标准。     

Exposure to high background radiation level in the tin mining area of Jos Plateau, Nigeria.

The present work deals with the radioactivity of samples of tin tailings collected from a mining site in Jos, Nigeria. The activity concentrations of the samples were measured using a gamma-ray spectrometer with a hyper-pure germanium detector. In situ dose rates at the site were also measured using a precalibrated survey meter. Potassium-40 was not detected in any of the studied samples. The activity concentrations of (238)U and (232)Th ranged from 17.1 x 10(2) to 16.6 x 10(3) Bq kg(-1) and from 52.9 x 10(2) to 47.5 x 10(3) Bq kg(-1), with mean values of 72.2 x 10(2) and 16.8 x 10(3) Bq kg(-1), respectively. The absorbed dose rates were between 4.0 and 36.3 microGy h(-1), with a mean value of 13.5 microGy h(-1), which is much higher than the world average of 0.06 microGy h(-1) for soil. The calculated effective dose rates varied between 2.8 and 25.4 microSv h(-1), with a mean value of 9.4 microSv h(-1), whereas the effective dose rates obtained for the in situ measurement varied between 6.0 and 28.0 microSv h(-1). The annual gonadal dose equivalent was calculated as 92.4 mSv. This is much higher than the world average dose equivalent rate to individuals from soil (0.30 mSv y(-1)).     

Radioactive rock phosphate: the feed stock of phosphate fertilizers used in Pakistan

The existence of natural radioactivity in phosphate fertilizers originates from the rock phosphate that is used as a feed stock for the manufacturing of various types of phosphate fertilizers. Gamma ray activity mass concentrations have been determined in phosphate rock and fertilizer samples collected from different fertilizer manufacturing factories and suppliers in Pakistan. The technique of gamma ray spectrometry was applied using a HPGe (high purity germanium) gamma ray detector coupled with a personal computer (PC) based multichannel analyzer (MCA). The specific activity values of 40K, 226Ra, and 232Th were widely distributed in the rock and fertilizer samples. Activity mass concentrations of 238U (226Ra) in the rock phosphate from Jordan and Pakistan were 428 +/- 11 and 799 +/- 10 Bq kg(-1), respectively, and that in the triple-superphosphate fertilizer was 701 +/- 21 (-1), which was greater than the average values of 238U (226Ra) for other types of fertilizers under study. The concentrations of 40K and 232Th were of the order of background level on the Earth's crust. Chemical analysis for concentration of different constituents in rock phosphate was also carried out. The higher the concentrations of P2O5 and K2O were, the higher the specific activities of 226Ra and 40K were, respectively, in the rocks under study. The amount of radioactivity in the rock phosphate is a source of continuous exposure to radiation, which varies widely depending upon the origin and grade of rock; therefore, radiation dose rate has been estimated. The values of dose rate and other derived quantities were many folds larger than the limits specified for those quantities.     

Measurement of the natural radioactivity in building materials used in Ankara and assessment of external doses

A total of 183 samples of 20 different commonly used structural and covering building materials were collected from housing and other building construction sites and from suppliers in Ankara to measure the natural radioactivity due to the presence of (226)Ra, (232)Th and (40)K. The measurements were carried out using gamma-ray spectrometry with two HPGe detectors. The specific activities of the different building materials studied varied from 0.5 +/- 0.1 to 144.9 +/- 4.9 Bq kg(-1), 0.6 +/- 0.2 to 169.9 +/- 6.6 Bq kg(-1) and 2.0 +/- 0.1 to 1792.3 +/- 60.8 Bq kg(-1) for (226)Ra, (232)Th and (40)K, respectively. The results show that the lowest mean values of the specific activity of (226)Ra, (232)Th and (40)K are 0.8 +/- 0.5, 0.9 +/- 0.4 and 4.1 +/- 1.4 Bq kg(-1), respectively, measured in travertine tile while the highest mean values of the specific activity of the same radionuclides are 78.5 +/- 18.1 (ceramic wall tile), 77.4 +/- 53.0 (granite tile) and 923.4 +/- 161.0 (white brick), respectively. The radium equivalent activity (Ra(eq)), the gamma-index, the indoor absorbed dose rate and the corresponding annual effective dose were evaluated to assess the potential radiological hazard associated with these building materials. The mean values of the gamma-index and the estimated annual effective dose due to external gamma radiation inside the room for structural building materials ranged from 0.15 to 0.89 and 0.2 to 1.1 mSv, respectively. Applying criteria recently recommended for building materials in the literature, four materials meet the exemption annual dose criterion of 0.3 mSv, five materials meet the annual dose limit of 1 mSv and only one material slightly exceeds this limit. The mean values of the gamma-index for all building materials were lower than the upper limit of 1.     

Radon emanation in Saskatchewan soils

Saskatchewan prairie soils in central Canada were studied from areas where many homes are known to exceed the Health Canada indoor radon guideline of 200 Bq m. This study sampled 32 soils from 11 sites, which varied in clay content and presence of bedrock materials. Soils were analyzed for (238)U, (226)Ra, (222)Rn in soil gas, bulk density, moisture, and particle size. Radon emanation from the soil samples varied from 10% to 43% and increased significantly with clay content with radon concentrations in soil gas of 18-38 kBq m(-3). Total uranium in soils was 2.1-4 ppm and 26-51 Bq kg(-1) dry weight for (238)U, (234)Th, and (226)Ra. Homes built on soils with high clay content may be at greater risk of high radon levels, particularly when the soils are dry and cracked, enhancing their permeability to gases such as radon. One sample of coal bedrock, originating from Tertiary marine shales, was particularly high for total uranium (53 ppm), (238)U, (234)Th, and (226)Ra activities (68-1,303 Bq kg(-1)) with radon emanation up to 1,363 kBq m(-3).     

Natural soil gamma radioactivity levels and resultant population dose in the cities of Zacatecas and Guadalupe,Zacatecas, Mexico

The study of natural gamma radioactivity was made to determine the concentrations of natural radionuclides in soil. Twenty soil samples collected in the cities of Zacatecas and Guadalupe and their suburban areas in the Mexican state of Zacatecas were analyzed by gamma-ray spectrometry to determine the activity concentrations of 226Ra, 232Th, and 40K. Gamma-spectrometry measurements were made using a hyperpure germanium detector surrounded with shielding material to reduce the background counting rate. The GammaVision-32 MCA emulation software was used for gamma-ray spectrum analysis and the TRUMP card of 2k as a MCA emulator. Conversion factors were used to calculate the dose to the population from outdoor exposure to terrestrial gamma rays. The measured activity concentration of 226Ra varies from 11 to 38 Bq kg(-1), the activity concentration of 232Th varies from 8 to 38 Bq kg(-1). The activity concentration of 40K is in the range 309-1,049 Bq kg(-1). The overall population mean outdoor terrestrial gamma dose rate is 44.94 nGy h(-1).     

Radioactive analysis of cement and its products collected from Shaanxi, China

This note presents a study of 226Ra, 232Th, and 40K in cement and its products manufactured in some areas of Shaanxi, China. The concentrations of 226Ra, 232Th, and 40K were 46.2, 28.4, and 137.4 Bq kg(-1), respectively, for cement brick; and 64.7, 48.7, and 161.3 Bq kg(-1), respectively, for cement plaster. The concentration of 226Ra, 232Th, and 40K in cement ranges from 34.7 to 68.3 Bq kg(-1) with a mean value of 56.5 Bq kg(-1), 18.5 to 51.7 Bq kg(-1) with a mean value of 36.5 Bq kg(-1), and 126.8 to 224.6 Bq kg(-1) with a mean value of 173.2 Bq kg(-1), respectively. The measured activity concentrations for these radionuclides were compared with the reported data of other countries. The radium equivalent activities (Raeq), external hazard index (Hex) and internal hazard index (Hin) associated with the radionuclides were calculated. The Raeq values of cement and cement products are lower than the limit of 370 Bq kg(-1), equivalent to a gamma dose of 1.5 mSv y(-1). The values of Hex and Hin are less than unity.     

Natural radioactivity in the soil samples of Coastal Karnataka of South India

Studies on radiation level and radionuclide distribution in the region of Coastal Karnataka, India, were undertaken. The purpose of this study is to provide baseline data on radiation level and radionuclide distribution in the region for the future assessment of the impact of the nuclear and thermal power stations that are being set up in the region. Further, this study may reveal information on the transportation of radionuclides in the environment. The external gamma dose rates in air have been measured throughout Coastal Karnataka using a sensitive plastic scintillometer. The measured dose rates include both terrestrial and cosmic ray components. The gamma dose rates in air range from 26 to 174 nGy h(-1) with a median value of 74 nGy h(-1). The activities of naturally occurring radionuclides in the soil samples of the region were measured using HPGe gamma ray spectrometry, and the resulting doses in air were calculated. The activity of 40K varies from 61.0 to 316.7 Bq kg(-1) with a median of 117.5 Bq kg(-1); the activity of 226Ra varies from 20.1 to 62.3 Bq kg(-1) with a median value 35.0 Bq kg(-1) and that of 232Th from 14.3 to 48.6 Bq kg(-1) with a median value of 29.8 Bq kg(-1). The mean absorbed dose rate in air due to naturally occurring radionuclides is found to be 41.5 nGy h(-1). In addition to this, the correlations between 226Ra and 40K, 232Th and 40K, and 226Ra and 232Th were computed from the results of the concentration of these naturally occurring radionuclides. A weak correlation was observed between 226Ra and 40K and between 232Th and 40K while a moderately good correlation was observed between 226Ra and 232Th. The results of these systematic investigations are presented and discussed in this paper.