Long-term immune and cytogenetic effects of high level natural radiation on Ramsar inhabitants in Iran

Ramsar, a northern coastal city of Iran, overlooking the Caspian Sea, has some high level natural radiation areas (HLNRAs) as well as over 50 hot springs with low and high radium contents used as spas by the public and vacationers. The average whole body dose received by population in these areas is about 5 times higher than the normal background radiation level. Studies on the long-term effects of high level natural radioactivity on some immunological and cytogenetical parameters, in the Ramsar inhabitants are summarized in this paper. Our results showed a significant increase of CD69 expression on TCD4+ stimulated cells (P < 0.004) and a significant increase of total serum IgE (P < 0.05), and also higher incidence of stable and unstable chromosomal aberrations in the HLNRA group compared to the control group with normal background radiation (P < 0.05).Other humoral immune parameters, did not show significant differences between the two groups.     

226Ra concentration in the teeth of habitants of areas with high level of natural radioactivity in Ramsar

The level of natural radiation in some regions of Ramsar, a northern coastal city of Iran, is known to be among the highest levels of natural radiation in the world. 226Ra existing in high concentrations in the soil of this region is washed by underground water and transferred to the surface. In this way, 226Ra enters the food chain of residents and substitutes within the hard body tissues of humans. 226Ra is one of the so-called bone seekers as its metabolic processes in the human body are similar to calcium and remains in hard tissues of body because of its long half-life, and being an alpha emitter causes dangerous effects on human health. The purpose of this study is to determine the concentration of 226Ra in the teeth of residents of these high-level natural radiation areas, compared with a control group. Thirteen teeth in five groups were studied as the case group and thirteen teeth in five corresponding control groups were inspected. The mean values of the activity of 226Ra in the case group and in the control group were 0.32 and 0.18mBqg(-1), respectively.     

Evaluation of DNA damage in the root cells of Allium cepa seeds growing in soil of high background radiation areas of Ramsar-Iran

Plants are unique in their ability to serve as in situ monitors for environmental genotoxins. We have used the alkaline comet assay for detecting induced DNA damage in Allium cepa to estimate the impact of high levels of natural radiation in the soils of inhabited zones of Ramsar. The average specific activity of natural radionuclides measured in the soil samples for (226)Ra was 12,766Bqkg(-1) whereas in the control soils was in the range of 34-60Bqkg(-1). A positive strong significant correlation of the DNA damage in nuclei of the root cells of A. cepa seeds germinated in the soil of high background radiation areas with (226)Ra specific activity of the soil samples was observed. The results showed high genotoxicity of radioactively contaminated soils. Also the linear increase in the DNA damage indicates that activation of repair enzymes is not triggered by exposure to radiation in HBRA.     

Evaluation of DNA damage in the root cells of Allium cepa seeds growing in soil of high background radiation areas of Ramsar – Iran

Plants are unique in their ability to serve as in situ monitors for environmental genotoxins. We have used the alkaline comet assay for detecting induced DNA damage in Allium cepa to estimate the impact of high levels of natural radiation in the soils of inhabited zones of Ramsar. The average specific activity of natural radionuclides measured in the soil samples for ²²⁶Ra was 12,766 Bq kg⁻¹ whereas in the control soils was in the range of 34–60 Bq kg⁻¹. A positive strong significant correlation of the DNA damage in nuclei of the root cells of A. cepa seeds germinated in the soil of high background radiation areas with ²²⁶Ra specific activity of the soil samples was observed. The results showed high genotoxicity of radioactively contaminated soils. Also the linear increase in the DNA damage indicates that activation of repair enzymes is not triggered by exposure to radiation in HBRA.     

Exposure to (226)Ra from consumption of vegetables in the high level natural radiation area of Ramsar-Iran

The vegetable-to-soil concentration ratio (CR) for (226)Ra and the related effective dose were studied in Talesh Mahalleh, a district of the city of Ramsar in Iran with a high level of natural radiation (HLNR). Maximum and minimum CR were measured in leafy and root vegetables with average values of 1.6 x 10(-2) and 4.0 x 10(-3), respectively. The mean effective dose resulting from (226)Ra due to consumption of edible vegetables by adults in the critical group in this region was estimated to be 72.3 microSv a(-1). This value is about 12 times greater than the average of effective dose resulting from this radionuclide due to combined intake of all foods and drinking water in normal background areas.     

Realistic retrospective dose assessments to members of the public around Spanish nuclear facilities

In the frame of an epidemiological study carried out in the influence areas around the Spanish nuclear facilities (ISCIII-CSN, 2009. Epidemiological Study of The Possible Effect of Ionizing Radiations Deriving from The Operation of Spanish Nuclear Fuel Cycle Facilities on The Health of The Population Living in Their Vicinity. Final report December 2009. Ministerio de Ciencia e Innovación, Instituto de Salud Carlos III, Consejo de Seguridad Nuclear. Madrid. Available from: http://www.csn.es/images/stories/actualidad_datos/especiales/epidemiologico/epidemiological_study.pdf), annual effective doses to public have been assessed by the Spanish Nuclear Safety Council (CSN) for over 45 years using a retrospective realistic-dose methodology. These values are compared with data from natural radiation exposure. For the affected population, natural radiation effective doses are in average 2300 times higher than effective doses due to the operation of nuclear installations (nuclear power stations and fuel cycle facilities). When considering the impact on the whole Spanish population, effective doses attributable to nuclear facilities represent in average 3.5 × 10⁻⁵ mSv/y, in contrast to 1.6 mSv/y from natural radiation or 1.3 mSv/y from medical exposures.     

Indoor radon monitoring in Northern Iran using passive and active measurements

In this work we present the results of a 2-year survey of indoor radon variations in four cities of Lahijan, Ardabil, Sar-Ein and Namin in North and Northwest Iran. We used both passive and active measurements by solid state nuclear track detectors (SSNTDs) with CR-39 polycarbonate and PRASSI Portable radon Gas Surveyor. A total of 1124 samplers in Lahijan, Ardabil, Sar-Ein and Namin were installed. Sampling frequency was seasonal and sampling locations were randomly chosen based on dwelling structures, floors, geological formations, elevation and temperature variation parameters. For quality assurance, 281 active measurements and double sampling were carried out. Based on our results and the results of previous surveys, Ardabil and Lahijan have the second and third highest radon concentration in Iran, respectively (Ramsar is first). The average radon concentration during the year in Lahijan, Ardabil, Sar-Ein and Namin were 163, 240, 160 and 144 Bq/m(3) with medians of 160, 168, 124 and 133 Bq/m(3), respectively. These concentrations give rise to annual effective doses of 3.43 mSv/y for Lahijan and 5.00 mSv/y for Ardabil. The maximum recorded concentration was 2386 Bq/m(3) during winter in Ardabil and the minimum concentration was 55 Bq/m(3) during spring in Lahijan. Relationships between radon concentration and building materials and room ventilation were also studied. The dosimetry calculations showed that these four cities could be categorized as average natural radiation zones. The correlation coefficients relating warm and cold season radon variation data were obtained.     

Natural radioactivity and radiation exposure in the high background area at Chhatrapur beach placer deposit of Orissa, India

A high natural background radiation area is reported for the Chhatrapur beach placer deposit of Orissa state, on the southeastern coast of India, due to the presence of radiogenic heavy minerals. The average activity concentrations of radioactive elements 232Th, 238U and 40K were measured by gamma-ray spectrometry using a HPGe detector, and found to be 2500 +/-1850, 230 +/- 140 and 120 +/- 35 Bq kg-1, respectively, for the bulk sand samples. The absorbed gamma dose rates in air due to the naturally occurring radionuclides varied from 375 to 5000 nGy h-1, with an average value of 1625 +/- 1200 nGy h-1. The external annual effective dose rate of the region ranged from 0.46 to 6.12 mSv y-1, with an average value of 1625 +/- 1200 mSv y-1. The absorbed gamma dose rate levels of Chhatrapur beach area were similar to the monazite sand-bearing high background radiation areas of southern and southwestern coastal tracts of India and other similar areas of the world. The major contributors to the enhanced level of radiation are monazite and zircon sands.     

Radionuclide content of concrete building blocks and radiation dose rates in some dwellings in Ibadan, Nigeria

Thirty-two samples of concrete building blocks were collected from different block making industries in Ibadan. The radioactivity concentrations of the natural radionuclides in the samples were determined by gamma-ray spectrometry with a NaI(Tl) detector. The radioactivity concentrations varied from 6.2 to 57.5 Bq kg(-1), 12.4 to 64.9 Bq kg(-1) and 95.3 to 766.1 Bq kg(-1) for 226Ra, 232Th and 40K, respectively. The radium equivalent activities of the 32 samples varied from 51.3 to 175.7 Bq kg(-1). Radiation exposure levels in 30 dwellings were determined using LiF thermoluminescent dosimeters. The annual equivalent dose rates varied from 0.318 to 0.657 mSv y(-1) with a mean of 0.433 mSv y(-1). The annual effective dose rate to the whole body was calculated as 0.236 mSv y(-1), which is less than that (mean) estimated by UNSCEAR for normal background areas.     

Natural radiation exposure in the Campo Arañuelo region in the surroundings of Almaraz nuclear power station (Spain)

During 1998 regional surveys were conducted to evaluate natural radiation exposure of people in the vicinity of the six Spanish nuclear power stations. Indoor radon, external gamma dose rates outdoors and indoors and radioactivity in soil were measured in these surveys. The highest mean annual effective dose to the population was found in the surroundings of the Almaraz nuclear power plant in the province of Cáceres and was mainly due to the presence of high radon concentrations in homes. In order to make a more accurate assessment of the dose coming from the radon in this area, a new and more extensive surgery on indoor radon with a total of 380 measurements was carried out in 2000 in the Campo Ara?uelo region around the Almaraz nuclear power station. From the results obtained in this survey, a population-weighted mean annual effective dose from radon exposure of 1.7 mSv y(-1), 44% lower than that previously reported in 1998, was estimated for the whole Campo Ara?uelo region. The maximum dose value due to radon exposure, about 4 mSv y(-1), was reached in the so-called La Vera area located in the north of this region. The relationship between the indoor radon concentrates experimentally measured, the geological characteristics of this geographic area and the information provided by the radiation map of the Spanish MARNA Project is also analyzed, confirming that La Vera area should be considered as a high radon level area.     

Regional dependence of urinary uranium baseline levels in non-exposed subjects with particular reference to volunteers from Northern Italy

Knowledge of the level of natural uranium (U) in the human body is fundamental in order to estimate the potentially hazardous incorporation in accidentally exposed subjects. A constant monitoring of exposed workers needs reliable reference baseline values, which can be determined by measuring the U concentration in urine. ICPMS has proven to be a fast, reliable and highly sensitive technique for this purpose. Non-uniformity in the distribution of U levels in various regions and differences in dietary habits account for the significant regional variations of U concentration in urine in non-exposed subjects. In this paper, the determination of daily uranium urinary excretion levels in a group of 12 non-exposed subjects from Northern Italy is presented and compared to data present in the published literature and to values obtained in a larger group of German volunteers. The urinary U output values observed in the Italian subset are generally higher than the corresponding levels measured in other groups. This could be the result of a higher intake of U from liquids, as assessed by the determination of U concentration in drinking waters.     

Radiation doses of Swiss population from external sources

The outdoor radiation exposure of the population in Switzerland from external sources results from cosmic background as well as from natural and artificial ground radiation. The geographical distribution of these components and of the total dose rate are represented on maps consisting of 2 kmx2 km grid cells. The average dose rate on Swiss territory outdoors is 147 nSv/h (1.29 mSv/a). The distributions are then related to the population density distribution by GIS application. The population is exposed to an average dose rate of 108 nSv/h (0.95 mSv/a) per capita which is just below the threshold for man-made dose rate given by national regulation. The lower value (relative to the country average 147 nSv/h) arises from the fact that most of the population lives north of the Alps where the lithology is dominated by rocks of relatively low radioactivity and where the cosmic radiation is low relative to the Alps.     

Assessment of radiation exposure in the uranium mining and milling area of Mailuu Suu, Kyrgyzstan

The area of the town of Mailuu Suu, Kyrgyzstan, is polluted by radionuclides and heavy metals from tailing dumps and heaps resulting from the historic exploitation of uranium mines. In the frame of a European Commission-TACIS funded project, radiological assessment was performed for critical group members living in the city of Mailuu Suu, located downstream the tailings, or in the village of Kara Agach, partially located on a uranium mine waste dump. The actual external exposure is around 1.2 mSv a(-1) at both locations and exposure from radon is around 3 mSv a(-1) at Mailuu Suu and around 10 mSv a(-1) at Kara Agach. Ingestion dose was negligible for a critical group member living at Mailuu Suu. At Kara Agach, however, under the hypothesis that all food and fodder is cultivated locally, exposure from ingestion is much higher ( approximately 10-30 mSv a(-1)). In case of an accidental scenario [(part of) Tailing 3 content thrust to river], estimated additional maximum doses result in 45 and 77 mSv for an adult and a child, respectively.     

The application of phosphogypsum in agriculture and the radiological impact

Radium-226 in phosphogypsum produced in a phosphate industry, SICNG operating at Thessaloniki, Northern Greece since May 1966, varied from 261 to 688 Bq kg(-1) (mean value 508 Bq kg(-1)). This radionuclide in soil tilled with phosphogypsum used for agricultural purposes varied from 50 to 479 Bq kg(-1) (average 205 Bq kg(-1)), while in the regular soil of cultivated fields it varied from 37 to 54 Bq kg(-1) (average 48 Bq kg(-1)). Radium-226 in rice originated from cultivated fields tilled with phosphogypsum or not varied from 0.36 to 1.98 Bq kg(-1) (average 1.53 Bq kg(-1)) with the higher values observed in samples originated from cultivated fields tilled with phosphogypsum. Radium-226 transfer factors, TF, from soil tilled with phosphogypsum to plants for the case of rice varied from 6.5 x 10(-3) to 2.0 x 10(-2) (geometric mean: 1.1 x 10(-2)). A mean (226)Ra content in rice 1.53 Bq kg(-1) results in a daily intake of (226)Ra by humans in Greece 0.0084 Bq day(-1) leading to an annual effective dose for adults 0.86 microSv y(-1) which is much less in contributing to the average exposure to natural radiation sources (2.4 mSv y(-1)) and particularly to the part due to ingestion (0.29 mSv y(-1)). It is necessary to continuously control (monitoring) (226)Ra in phosphogypsum before any use for agricultural purposes.     

Concentration of 226Ra in Hungarian bottled mineral water

Concentration of the radionuclide 226Ra was determined in almost every type of bottled mineral water commercially available in Hungary. Determination of the radon coming from the radium dissolved in the water was used for activity measurement. As the results show, the 226Ra concentrations exceed the level of 100 mBq l(-1) in six cases out of the 28 types of mineral water investigated. In one case 3 Bq l(-1) was measured, which provides 0.3 mSv year(-1) committed effective dose for adults in the case of a consumption rate of 1 l day(-1). In soft drinks produced from mineral water a concentration of 2.6 Bq l(-1) was determined, which means 1.4 mSv year(-1) effective dose in the age group 12-17 years in the case of permanent daily drinking of 1 l of these beverages.     

Radon levels in Cyprus

Radon levels in atmospheric and aquatic systems in Cyprus have recently been measured using the radon monitor Alpha Guard. Indoor and outdoor radon levels were obtained in situ, whereas analysis of radon concentrations in water was performed using tap and ground water samples collected from several areas of the island. The average value for outdoor and indoor radon concentration is 11+/-10 and 7+/-6 Bq m(-3), respectively, and for tap and ground water 0.4 Bq l(-1) and 1.4 Bq l(-1), respectively. From these data the annual dose equivalent of airborne radon to the Cypriot population is about 0.19 mSv y(-1), which is quite low compared to the total dose equivalent of natural and man-made ionising radiation in Cyprus. Radon levels in aquatic systems are relatively low due to an exhaustive utilisation of ground water resources and also to the increased input of desalinated sea water in the water distribution network and eventually into the ground water reservoirs.     

Gamma radiation measurements and dose rates in commercially-used natural tiling rocks (granites)

The gamma radiation in samples of a variety of natural tiling rocks (granites) imported in Cyprus for use in the building industry was measured, employing high-resolution gamma-ray spectroscopy. The rock samples were pulverised, sealed in 1-l plastic Marinelli beakers, and measured in the laboratory with an accumulating time between 10 and 14 h each. From the measured gamma-ray spectra, activity concentrations were determined for (232)Th (range from 1 to 906 Bq kg(-1)), (238)U (from 1 to 588 Bq kg(-1)) and (40)K (from 50 to 1606 Bq kg(-1)). The total absorbed dose rates in air calculated from the concentrations of the three radionuclides ranged from 7 to 1209 nGy h(-1) for full utilization of the materials, from 4 to 605 nGy h(-1) for half utilization and from 2 to 302 nGy h(-1) for one quarter utilization. The total effective dose rates per person indoors were determined to be between 0.02 and 2.97 mSv y(-1) for half utilization of the materials. Applying dose criteria recently recommended by the EU for superficial materials, 25 of the samples meet the exemption dose limit of 0.3 mSv y(-1), two of them meet the upper dose limit of 1 mSv y(-1) and only one clearly exceeds this limit.     

Evaluation of technologically enhanced natural radiation near the coal-fired power plants in the Lodz region of Poland

Radionuclide releases together with escaping fly ashes (from 45 x 10(6) kg in previous decades to 8 x 10(6) kg annually in 1996) from the main local and several small coal-fired power plants resulted in a relatively small increase in natural radioactivity levels in the Lodz region. The natural gamma terrestrial radiation dose rates (1 m above ground level) were measured at 82 points including in the vicinity of power plants, in the center of the town and on edge of the town. The average dose rate value for the first area was 36 +/- 1.2 nGy h (-1), whereas the same dose rate for the edge of town was slightly lower 30 +/- 0.9 nGy h (-1) but this difference was statistically significant. Further confirmation of the technologically slightly enhanced exposure of the local population to natural radionuclides was achieved by gamma-spectrometry measurement of the uranium and thorium decay series radionuclides in the surface soil profiles (up to 30 cm depth). The average increase of 226Ra and 232Th radionuclides in the top layer of soil (0-10 cm) according to the 20+/-30 cm depth layer was 21% and 17%, respectively. However, due to the relatively low levels of 232Th (14.3 Bq kg (-1)) and 238U (16.8 Bq kg (-1)) in this area, the annual average effective dose from the natural terrestrial radiation for the local population is also relatively low, 0.28 mSv only.     

Adaptive response in frogs chronically exposed to low doses of ionizing radiation in the environment

Using the micronucleus assay, decreased levels of DNA damage were found after high dose ionizing radiation exposure of liver cells taken from frogs inhabiting a natural environment with above-background levels of ionizing radiation, compared to cells taken from frogs inhabiting background areas. The data obtained from a small number of animals suggest that stress present in the above-background environment could induce an adaptive response to ionizing radiation. This study did not reveal harmful effects of exposure to low levels of radioactivity. On the contrary, stress present in the above-background area may serve to enhance cellular defense mechanisms.     

Biological consequences of increased natural radiation background for Microtus oeconomus Pall. populations

The results of long-term investigations (1981-1999) on the state of Microtus oeconomus Pall. (tundra vole) population, living under the increased natural radiation background for a long time (for more than 100 generations), are presented. Population density dynamics, morphophysiological parameters, state of the lipid peroxidation regulatory system in different tissues and the cytogenetic effects in bone marrow cells of animals have been analyzed. It is shown that tundra voles from the studied radioactively contaminated areas differ from those on natural radiation background area for the parameters measured. The results of this long-term investigation show that qualitatively new sub-populations of tundra vole on these areas have evolved, which are able to survive in radioactively contaminated environment.