Radiological assessment of Abu-Tartur phosphate, Western Desert Egypt

The contents of natural radionuclides (²²⁶Ra, ²³²Th and ⁴⁰K)were measured in sedimentary phosphate rock samples (Abu-Tarturphosphate, Western Desert Egypt) by using gamma spectrometry(NaI (Tl) 3"x 3"). Phosphate and environmental samples werecollected from Abu-Tartur phosphate mine and the surroundingregion. The results are discussed and compared with the levelsin phosphate rocks from different countries. The activitiesof ²²⁶Ra, ²³²Th series and ⁴⁰K are between (14.9 ± 0.8and 302.4 ± 15.2), (2.6 ± 1.0 and 154.9 ±7.8) and (10.0 ± 0.5 and 368.4 ± 18.4) Bq kg^–1,respectively. The Abu-Tartur phosphate deposit was found tohave lower activity than many others exploited phosphate sedimentarydeposits, with its average total annual dose being only 114.6µSv y^–1. This value is about 11.46% of the 1.0 mSvy^–1 recommended by the International Commission on RadiologicalProtection (ICRP-60, 1990) as the maximum annual dose to membersof the public.     

Activity concentrations of 226Ra and 228Ra in drilled well water in Finland

The activity concentrations of (226)Ra and (228)Ra in drinking water were determined in water samples from 176 drilled wells. (226)Ra activity concentrations were in the range of <0.01-1.0 Bq l(-1) and (228)Ra activity concentrations in the range of <0.03-0.3 Bq l(-1). The mean activity concentration of (226)Ra and (228)Ra were 0.041 and 0.034 Bq l(-1), respectively. High radium activity concentrations in drinking water were rare. Only 2-4% of the drilled wells exceeded a (226)Ra concentration of 0.5 Bq l(-1) and 1-2% of the wells exceeded a (228)Ra concentration of 0.2 Bq l(-1). These are the activity concentrations that cause a 0.1 mSv annual effective dose for users of drinking water. The maximum annual effective doses from (226)Ra and (228)Ra for users of drilled wells were 0.21 mSv, and 0.16 mSv respectively. The elevated activity concentrations of (226)Ra and (228)Ra did not occur simultaneously in the same groundwaters and the correlation between (226)Ra and (228)Ra was small.     

Determination of natural radioactivity in drinking water in private dug wells in Akure, Southwestern Nigeria

Gamma spectrometry of well water was done to measure the activity concentrations of gamma-emitters 226Ra and 228Ra from 238U and 232Th series, respectively, and 40K in their waters. Measurements were done using high-purity (HPGe) co-axial detectors (Canberra, GC 2018-7500 ) coupled to Canberra Multichannel Analyser system. Activity concentrations ranged from 0.57 to 26.86, 0.20 to 60.06 and 0.35 to 29.01 Bq l(-1) for 226Ra, 228Ra and 40K, respectively. Activity concentrations were compared with data from other parts of the world and used to estimate annual effective dose for three age groups. Total annual effective doses from the intake of these radionuclides in the waters ranged from 0.02 to 76.84, 0.02 to 38.80 and 0.05 to 481.60 mSv y(-1) for age group <1, 2-7 and > or =17 y, respectively. These values are considerably higher than both the World Health Organisation and the International Commission on Radiological Protection limits.     

Assessment of annual effective dose from 238U and 226Ra due to consumption of foodstuffs by inhabitants of Tehran city, Iran

The concentrations of (238)U and (226)Ra were determined in different foodstuffs purchased from markets in Tehran. Determinations of the radionuclides have been carried out using alpha spectrometry technique, on samples of egg, lentil, potato, rice, soya, spinach, tea and wheat. Average concentrations of natural radionuclides and foodstuff consumption rate were used to assess annual intake and based on intake values, the annual effective ingestion dose has been estimated for Tehran city residents. The measurement results show that soya has the maximum concentration of (238)U equal to 15.6 +/- 2.6 mBq kg(-1) and tea has the maximum concentration of (226)Ra equal to 1153.3 +/- 265.3 mBq kg(-1). Besides, the maximum annual effective dose from (238)U and (226)Ra were assessed to be 2.88 x 10(-2) +/- 7.20 x 10(-3) and 2.15 +/- 0.54 muSv, respectively, from wheat samples.     

Exposure to radon in dwellings in the Sharri community, Kosovo

Indoor air radon concentration was measured by exposing etchedtrack detectors in the sleeping and living rooms of 18 housesin 6 villages of the Sharri community in Kosovo. Values rangedfrom 24 to 209 Bq m^–3, with only one exceeding 200 Bqm^–3, with a geometric mean and geometric standard deviationof 95.4 Bq m^–3 and 1.6, respectively. On the basis ofthe assumption that the spring radon concentrations obtainedin this survey represent the yearly average, annual effectivedoses of residents were calculated; they range from 0.89 to4.7 mSv y^–1, with the geometric mean and geometric standarddeviation of 1.5 mSv y^–1 and 2.2, respectively. No mitigationmeasures are planned to be undertaken.     

Measurement of natural radioactivity in bottled drinking water in Pakistan and consequent dose estimates

Natural radioactivity was determined in 11 different brands of commonly sold bottled drinking water in the federal capital Islamabad and Rawalpindi city of Pakistan using gamma spectrometry technique. Mean concentrations of 226Ra, 232Th and (40)K were found to be 11.3 +/- 2.3, 5.2 +/- 0.4 and 140.9 +/- 30.6 mBq l(-1), respectively. The annual cumulative effective doses due to all three natural radionuclides for different age groups of 1-5 y, 5-10 y, 10-15 y and adults (>or=18 y) were estimated to be 4.0, 3.4, 3.1 and 4.1 microSv y(-1), respectively. Among the three natural radionuclides, annual effective doses for all age groups from 226Ra were significant. Children in the age group of 1-5 y appeared to be at risk with respect to the annual effective doses from 226Ra as compared to the other age groups. Results obtained in this study are compared with the reported values from other countries of the world and it was observed that measured activity concentrations of three natural radionuclides in the bottled drinking water were lower than these values. Annual estimated effective doses for all four age groups from the intake of natural radionuclides in bottled drinking water were also found below the World Health Organisation (WHO) recommended limit of 0.1 mSv y(-1) as well as the average radiation dose of 0.29 mSv y(-1) received per head worldwide due to ingestion of natural radionuclides assessed by UNSCEAR (2000).     

Determination of 238U, 234U, 232Th, 228Th, 228Ra, 226Ra and 210Pb concentration in excreta samples of inhabitants of a high natural background area

The high concentration of uranium and thorium in certain Brazilian areas provides an opportunity to evaluate the radiation exposure due to intake of radionuclides by the populations that live and work in areas with a high natural radiation background. Buena, where this study was conducted, is a small village on the coast in the northern part of Rio de Janeiro State, characterised by the presence of a large deposit of monazite sand. In this paper, the concentrations of 238U, 234U, 232Th, 228Th, 228Ra, 226Ra and 210Pb in faecal samples from inhabitants of this area were determined by a sequential analytical method. The results of the average concentrations in faeces of inhabitants of Buena are 9.4 +/- 3.4 mBq g(ash)(-1) for 238U, 9.2 +/- 4.0 mBq g(ash)(-1) for 234U, 7.0 +/- 4.2 mBq g(ash)(-1) for 232Th, 256.1 +/- 134.6 mBq g(ash)(-1) for 228Th, 335.5 +/- 192.8 mBq g(ash)(-1) for 228Ra, 156.6 +/- 74.1 mBq g(ash)(-1) for 226Ra and 66.7 +/- 17.7 mBq g(ash)(-1) for 210Pb. The results were compared with background concentrations from faecal samples from individuals living in Rio de Janeiro City. For most of the radionuclides analysed, the average concentration in faeces from inhabitants of the high natural radiation background was higher than the concentration found in Rio de Janeiro, considered a 'normal' background area.     

Radiation dose from cigarette tobacco

The radioactivity in tobacco leaves collected from 15 different regions of Greece before cigarette production was studied in order to estimate the effective dose from cigarette tobacco due to the naturally occurring primordial radionuclides, such as (226)Ra and (210)Pb of the uranium series and (228)Ra of the thorium series and or man-made radionuclides, such as (137)Cs of Chernobyl origin. Gamma-ray spectrometry was applied using Ge planar and coaxial type detectors of high resolution and high efficiency. It was concluded that the annual effective dose due to inhalation for adults (smokers) for (226)Ra varied from 42.5 to 178.6 microSv y(-1) (average 79.7 microSv y(-1)), while for (228)Ra from 19.3 to 116.0 microSv y(-1) (average 67.1 microSv y(-1)) and for (210)Pb from 47.0 to 134.9 microSv y(-1) (average 104.7 microSv y(-1)), that is the same order of magnitude for each radionuclide. The sum of the effective doses of the three natural radionuclides varied from 151.9 to 401.3 microSv y(-1) (average 251.5 microSv y(-1)). The annual effective dose from (137)Cs of Chernobyl origin was three orders of magnitude lower as it varied from 70.4 to 410.4 nSv y(-1) (average 199.3 nSv y(-1)).     

Measurement of natural radioactivity and assessment of associated radiation hazards in soil around Baoji second coal-fired thermal power plant, China

Activity concentrations of natural radionuclides (226)Ra, (232)Th and (40)K in soil around Baoji Second coal-fired thermal power plant of China were determined using gamma ray spectrometry. The mean activity concentrations of (226)Ra, (232)Th and (40)K in soil were found to be 40.3 ± 3.5, 59.6 ± 3.1 and 751.2 ± 12.4 Bq kg(-1), respectively, which are all higher than the corresponding average values in Shaanxi, Chinese and world soil. The radium equivalent activity (Ra(eq)), the air absorbed dose rate (D), the annual effective dose (E), the external hazard index (H(ex)) and internal hazard index (H(in)) were evaluated and compared with the internationally reported or reference values. All the soil samples have Ra(eq) lower than the limit of 370 Bq kg(-1) and H(ex) and H(in) less than unity. The overall mean outdoor terrestrial gamma air absorbed dose rate is ～86.6 ± 3.4 nGy h(-1) and the corresponding outdoor annual effective dose is 0.106 ± 0.004 mSv, which is higher than the worldwide average (0.07 mSv y(-1)) for outdoor's annual effective dose.     

Quantitative analysis of gamma-ray emitters radioisotopes in commercialised bottled water in Tunisia

A set of measurements have been conducted in order to determine the annual effective dose resulting from the ingestion of natural radionuclides present in eight different brands of bottled water commercialised in Tunisia. Using high-resolution gamma spectrometry technique, we have noted the presence of the following radionuclides: 214Bi, 226Ra, 228Ac, 212Pb, 235U and 40K. For all classes of age, only the radium concentration was found to be significant in the calculation of the equivalent dose. Some of the studied samples exceeded the reference level of 0.1 mSv y(-1) of effective dose.     

Variations of 226Ra Concentration in Waters of the Pacific

The ²²⁶Ra content was determined in waters of the hydrological fronts located in the western part of the Pacific and in the equatorial pelagic waters of the central part of the Pacific. The ²²⁶Ra concentration averaged throughout sampling sites was 4.3 ×10-14 g/l (standard deviation 2.0 × 10-14 g/l). The average ²²⁶Ra concentration in the pelagic waters was 3.5 ×10-14 g/l (N = 37, standard devation 1.5 ×10-14 g/l) and in the waters of the equatorial sampling area, 3.9 ×10-14 g/l (N = 28, standard deviation 1.5 ×10-14 g/l). The maximal variations of ²²⁶Ra concentration (from 1.6 to 6.5 ×10-14 g/l) were found in the pelagic waters in the vicinity of the frontal hydrological zones of the equatorial front. Variations of the ²²⁶Ra concentration in the surface waters caused by ²²⁶Ra bioaccumulation can reach 0.2%. These variations reflect the zonal distribution of the primary bioproduction.     

Comparison of measured and calculated spatial dose distributions for a bench-mark 106Ru/106Rh hot particle source

This study is a part of a programme of research to provide validateddose measurement and calculation techniques for beta emittinghot particles by the construction of well-defined model hotparticle sources. This enables parallel measurements and calculationsto be critically compared. This particular study concentrateson the high-energy beta emitter, ¹⁰⁶Ru/¹⁰⁶Rh (E_max = 3.54 MeV).This source is a common constituent of failed nuclear fuel,particularly in accident situations. The depth dose distributionswere measured using radiochromic dye film (RDF); an imagingphoton detector coupled to an LiF thermoluminescent dosemeter(LiF-IPD) and an extrapolation ionisation chamber (ECH). Dosecalculations were performed using the Monte Carlo radiationtransport code MCNP4C. Doses were measured and calculated asaverage values over various areas and depths. Of particularinterest are the doses at depths of 7 and 30–50 mg cm^–2,and averaged over an area of 1 cm², as recommended by the InternationalCommission on Radiological Protection for use in routine andaccidental over-exposures of the skin. In this case, the averageratios (MCNP/measurement) for RDF, ECH and LiF-IPD were 1.07± 0.02, 1.02 ± 0.01 and 0.83 ± 0.16, respectively.There are significantly greater discrepancies between the ECHand LiF-IPD measurement techniques and calculations—particularlyfor shallow depths and small averaging areas.     

Study of the distribution of ²²⁶Ra in ground water near the uranium industry of Jharkhand, India

Ground water is the principal source of drinking water in the rural areas of India. With the aim of determining, the contribution of (226)Ra to natural background radiation through drinking water exposure pathway near an operating uranium mining industry at Jaduguda, Jharkhand state of eastern India, the (226)Ra activity concentrations were measured in potable ground water. The water analysed, both tube well and well water, was collected in areas near the uranium industry and away. The (226)Ra concentration was measured by emanometric technique. The (226)Ra level in ground water was ranging between minimum detection limit of 3.5 mBq l(-1) and a maximum of 208 mBq l(-1). The analysis of variance reveals that there is insignificant statistical variation in the median (226)Ra concentration up to a distance of >10 km from the mining complex. Variation in concentration of (226)Ra in sources is attributed to the local geochemistry and environmental factors. The (226)Ra concentration was significantly elevated in natural artesian wells in the vicinity of uranium mineralised hill and it varies from 53.4 to 754 mBq l(-1). The WHO [Guidelines for Drinking Water Quality. Third Edition, Vol. 1, Recommendation (2004)] guideline value of 1000 mBq l(-1) has not been exceeded in any of the sources investigated.     

Study on external exposure doses from terrestrial radioactivity in Southern Vietnam

This paper presents the radioactivity concentrations of 226Ra, 232Th and 40K for 106 samples of surface soil collected in Southern Vietnam. The mean values of mass activity of radionuclides 226Ra, 232Th and 40K for Southern Vietnam are 28.6, 50.7 and 292.6 Bq kg(-1), respectively, which lead to the population-weighted absorbed dose rate of 54.5 nGy h(-1). The average annual effective doses outdoors, indoors and in total of Southern Vietnam are estimated to be 0.067, 0.374 and 0.441 mSv, respectively. The radium equivalent activity and the external hazard index of soil in Southern Vietnam are in the range 23.2-254.1 Bq kg(-1) and 0.06-0.69, respectively.     

Radiological of natural and mineral drinking waters in Slovenia

Various types of water were collected in Slovenia and analysed in order to assess the radiation doses from (238)U, (234)U, (228)Ra, (226)Ra, (210)Pb and (210)Po for three different age groups of the population. It was found in all cases that the calculated median committed effective dose from the investigated radionuclides for each population group was well below the recommended value of 100 μSv y(-1), ranging from 4 to 7 μSv y(-1) for adults, from 8 to 10 μSv y(-1) for children and from 6 to 7 μSv y(-1) for infants. Of the investigated groups of the population children are the most exposed with the highest absolute doses of 19.1 and 18.7 μSv y(-1) after drinking a certain bottled brand of mineral and natural water, respectively. The contribution of each particular radionuclide to total doses varied among different water types and within each type, as well as between different age groups.     

238U, 226Ra, 210Po concentrations of bottled mineral waters in Hungary and their committed effective dose

Nowadays the consumption of bottled mineral waters has become very popular. The average consumption of these is 0.36 l d(-1) per person in Europe. A considerable segment of the population drinks almost only mineral water as drinking water, which is about 1 l d(-1). As is known, some kinds of mineral waters contain naturally occurring radionuclides in higher concentration than the usual drinking (tap) water. The WHO (1993) legislation concerning the drinking waters does not include the mineral waters. In our work, the concentrations of (226)Ra, (238)U and (210)Po were determined in mineral waters available in Hungary. To determine the (226)Ra concentration the emanation method was used. The (238)U and (210)Po concentrations were determined by alpha spectrometry using semiconductor detector. The dose contribution was calculated using the radionuclide concentrations and the dose conversion factors from the Basic Safety Standard IAEA (1995), for 1 l d(-1) mineral water consumption. In some cases the calculated doses were considerable higher than the limit for drinking waters. Especially for children the doses can be remarkably high.     

Estimation of U, <Superscript>226</Superscript>Ra,and <Superscript>210</Superscript>Po Concentrations in Cauvery River Basin,South Interior Karnataka Region,India

The radioactivity concentration of ²¹⁰Po, ²²⁶Ra, and U in Cauvery river basin was analyzed using radiochemical analysis, emanometry, and LED fluorimetry, respectively. Due to transfer with water in cracks and pores, leaching, and heavy usage of phosphate fertilizers, ²¹⁰Po, ²²⁶Ra, and U radionuclides get into the environmental samples studied. The ²¹⁰Po concentration ranges from 0.7 ± 0.11 to 5.0 ± 0.7 and from 0.83 ± 0.12 to 5.2 ± 0.8 mBq L^–1; the ²²⁶Ra concentration, from 11.7 ± 1.8 to 62 ± 9 and from 10.5 ± 1.6 to 68 ± 10 mBq L^–1; and the U concentration, from 0.08 ± 0.01 to 4.4 ± 0.7 and from 2.0 ± 0.3 to 7.4 ± 1.1 ppb in river and borewell water samples, respectively.     

Activity concentrations and mean annual effective dose of foodstuffs on the island of Tenerife, Spain

A total of 26 different food types and 12 elaborated diets were analysed by low-level gamma spectrometry to measure their content of 238U(234Th), 228Ra(228Ac), 226Ra(214Pb), 210Pb, 137Cs and 40K. The concentrations of these radionuclides measured in some imported foodstuffs were compared with those measured in some locally produced ones. Moreover, the concentrations found in the analysed foodstuffs and composite diets were compared with the data available in literature from other locations, such as Egypt, Brazil, Poland and Hong Kong. 40K contributed highest to the daily dose produced by the intake of comestibles. The largest 40K concentrations were measured in the chickpeas and beans with 380 +/- 30 and 380 +/- 20 Bq kg(-1) fresh weights, respectively. The artificial radionuclide 137Cs was measured only above detection limits in the potatoes and sweet potatoes. A mean annual effective dose of 362 microSv with a standard deviation of 110 microSv was calculated from the composite diets.     

Natural radionuclides and dose estimation in natural water resources from Elba protective area, Egypt

The concentrations of the natural radionuclides (226)Ra, (232)Th and (40)K in 15 different water samples from Elba protective area, south-eastern desert of Egypt, have been determined using NaI(Tl) detector. Gamma ray spectrometric analysis was performed and the concentrations obtained for each of the radionuclides expressed in Bq l(-1) ranging from 1.6 to 11.1 for (226)Ra, 0.21 to 0.97 for (232)Th and 9.1 to 23 for (40)K. A reasonable correlation was found between (226)Ra, (232)Th concentrations and pH, although no general trend was observed with conductivity and total dissolved solids. The mean effective doses of 0.56 mSv y(-1) for (226)Ra, 0.065 mSv y(-1) for (232)Th and 0.04 mSv y(-1) for (40)K were estimated for the ingestion of these waters by adults.     

Natural radioactivity in tap waters of Eastern Black Sea region of Turkey

In this study, the activity concentrations of some radionuclides in tap water samples of the Eastern Black Sea region of Turkey were measured. The activity concentrations of radionuclides (214)Pb, (214)Bi, (40)K, (226)Ra and (137)Cs were determined using high resolution gamma ray spectrometry. Furthermore, (222)Rn activity concentrations in tap water samples were measured using Liquid Scintillation Counting. The mean specific activities of (214)Pb, (214)Bi, (226)Ra, (40)K, (137)Cs and (222)Rn in tap water samples were 6.73, 6, 19.16, 168.57, 5.45 mBq l(-1) and 10.82 Bq l(-1), respectively. These values are comparable with concentrations reported for other countries. The effective doses were determined due to intake of these radionuclides as a consequence of direct consumption of tap water samples. The estimated effective doses were 6.878 x 10(-4) microSv y(-1) for (214)Pb, 4.800 x 10(-4) microSv y(-1) for (214)Bi, 3.916 microSv y(-1) for (226)Ra, 0.763 microSv y(-1) for (40)K, 0.052 microSv y(-1) for (137)Cs and 5.848 microSv y(-1) for (222)Rn.