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.     

The consequences of chronic radiation exposure of scots pine in the remote period after the chernobyl accident

Long-term observations on Scots pine populations (2003–2012) were performed in areas of Bryansk region radioactively contaminated by the Chernobyl fallout. Throughout the observation period, the frequency of cytogenetic alterations in the root meristem of germinated seeds of pine trees from radioactively contaminated test sites significantly exceeded the control level. Seeds developing under chronic radiation exposure were characterized by high interannual variation in viability. The quality of the seeds and their resistance to additional γ-irradiation showed no definite relationship with the level of radioactive contamination in the site and the radiation dose absorbed by the generative organs of Scots pine.     

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.     

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.     

How long is long-term? reflections based on over 20 years of post-Chernobyl management in Norway

The radiation protection community has only recently started the important work of preparedness for long-term post-accidental management of radioactively contaminated areas, like for instance the EC projects STRATEGY, FARMING and EURANOS and the French authorities' CODIRPA and PAREX programmes. There are, however, different views concerning how long a long-term management might last. Based on the Norwegian and former Soviet Union experience after the Chernobyl accident, it is clear that a nuclear accident can entail decades of necessary management and rehabilitation of living conditions. The time period is dependent on a number of factors, e.g. amount of fallout, type of radionuclides, land use of contaminated area, number and density of people affected and available techniques and resources for implementing countermeasures. This paper discusses the management strategy implemented in Norway after the Chernobyl accident, the need for changing strategy over time and the important involvement of affected groups. Careful planning and reflections should be undertaken before actions are taken in the recovery phase, keeping in mind the possibility of decades with problems.     

Environmental radioactivity and thermoluminescence: A review

A close link exists between environmental radioactivity and thermoluminescence (TL) and this connection can be gainfully employed in (i) environmental radiation surveillance, (ii) radioactive prospecting and (iii) dating. The science of thermoluminescence dosimetry (TLD) is very well established for use in routine radiation monitoring. With the increased public awareness of health effects due to radioactivity releases from nuclear operations. TLDs have become indispensible ‘watchdogs’ in environmental surveillance; in high natural background areas such as the monazite regions, TLDs have yielded invaluable dosimetric data. Over large areas where the cosmic background can be assumed constant, the TLD-recorded radiation profiles can reflected the terrestrial gamma radioactivity distribution pattern and even seasonal variations in the radiation levels above ground may be delineated. A variety of natural materials like minerals, rocks, soils, sands, sediments, fossils, etc., as well as ancient artefacts like potteries and ceramic wares, yield TL even without any irradiation in the laboratory: the natural radioactivity in these materials, together with the radiation incident on them from the environment, causes a TL build-up during antiquity. It is possible to measure this natural TL and relate it to the natural radioactivity of the sample and hence to its age. In contrast, observations of a kind of anticorrelation between TL and a sample's radioactivity have also been made in recent times and the effect is mostly ascribable to alpha-radioactivity-induced damage effects.Typical results from recent investigations of the various aspects mentioned above are presented in this review, with particular emphasis on applications in India.     

The Chernobyl Forum: major findings and recommendations

The accident at the Chernobyl NPP in 1986 was the most severe in the history of the nuclear industry, causing a huge release of radionuclides over large areas of Europe. The recently completed Chernobyl Forum concluded that after a number of years, along with reduction of radiation levels and accumulation of humanitarian consequences, severe social and economic depression of the affected regions and associated psychological problems of the general public and the workers had become the most significant problem to be addressed by the authorities. The majority of the affected land is now safe for life and economic activities. However, in the Chernobyl Exclusion Zone and in some limited areas of Belarus, Russia and Ukraine some restrictions on land-use should be retained for decades to come. Most of the 600,000 emergency and recovery operation workers and five million residents of the contaminated areas in Belarus, Russia and Ukraine received relatively minor radiation doses which are comparable with the natural background levels. Apart from the dramatic increase in thyroid cancer incidence among those exposed at a young age and some increase of leukaemia and solid cancer in most exposed workers, there is no clearly demonstrated increase in the somatic diseases due to radiation.     

Field observations of the effects of protracted low levels of ionizing radiation on natural aquatic population by using a cytogenetic tool

In the present study, an effort is attempted to record the impact of chronic radiation on natural aquatic populations exposed to protracted doses (lower if compared to intervention levels but higher if compared to typical background) and to chemical pollution. The methodology is based on the analyses of chromosome aberrations observed in cells. Therefore, some preliminary research results on the cytogenetic effects on aquatic organisms of various taxa, in coastal ecosystems are presented, considering some selective regions of elevated natural gamma radiation and conventional pollution. These areas are the geothermal spring areas in the island of Ikaria-Eastern Aegean Sea and the port of Pireus, in Greece. The data are compared to the findings recorded in some organisms collected from the North Aegean Sea the early period after the Chernobyl accident. With regard to the different species examined, a first evaluation of the results is made using the reported field findings for the wide area of Chernobyl. The environmental assessment of the studied areas in terms of radiation impact is based on the cytogenetic injuries observed, and evidence of ecosystem disturbance is also pointed out. The final environmental assessment based on the quantified effects observed in the organisms from the studied areas takes into account a published conceptual model of zones of radiation dose rates and the resulting organism responses in a step function scale.     

High levels of fluctuating asymmetry in populations of Apodemus flavicollis from the most contaminated areas in Chornobyl

Random deviations from the perfect symmetry of normally bilaterally symmetrical characters for an individual with a given genotype occur during individual development due to the influence of multiple environmental factors. Fluctuating asymmetry (FA) is often used as a measure of developmental instability, and can be estimated as the variance of the distribution of differences between the left and right sides. We addressed the question of whether levels of FA were elevated in radioactively contaminated populations living around Chornobyl compared to those in reference populations of the yellow-necked mouse (Apodemus flavicollis). In addition, we studied amounts of directional asymmetry (DA) when one side is larger than the other on average. There was a significant difference among populations, including reference populations, in the amount of both FA and DA. A higher level of FA was documented for the contaminated populations in close proximity to the failed Chornobyl reactor for both the asymmetry of size and shape. The FAs of size and shape were highest in populations from the most contaminated locations in the Chornobyl exclusion zone. Although the directional asymmetry of shape was also highest in the contaminated populations, it was not significantly different from those in most of the reference populations. Populations from less contaminated areas inside the Chornobyl exclusion zone did not express FA values different from those of the reference populations outside the affected area. FA of skulls of A. flavicollis may indicate the degree to which the level of radioactive contamination affects the development of animals at Chornobyl. However, the mechanisms leading to these effects are not clear and probably vary from population to population. There were significant correlations between the overall right to left differences for the Procrustes aligned shape configurations, centroid sizes, and intramuscular (137)Cs. Detectable effects of radiation on developmental stability probably start to occur between 0.132 and 0.297 microGy/h.     

Uranium mine rehabilitation: the story of the South Alligator Valley intervention

The rehabilitation of radioactively contaminated sites is an activity generally regarded with suspicion by the community. This is certainly the case for Australian Aboriginal traditional landowners. This paper describes the historical background to, and the successful development and implementation of, a consultation and planning process to rehabilitate former uranium mining and milling facilities on Aboriginal lands of the World Heritage-listed Kakadu National Park in northern Australia. The process of developing an appropriate community communication and consultation process to allay concerns about radioactivity is a cornerstone of the rehabilitation program. The initial stages of the program's implementation are also described. This program is also the first example of a radiological intervention under modern environmental and radiation protection legislation in the region. It was necessary to develop radiological standards for use in the program as none had been promulgated under existing relevant legislation.     

Arthropods and birds in the forest–tundra of Western Siberia and the edge effect

Over 2500 species of invertebrate macrofauna and over 177 species of avifauna live in the forest–tundra of the Lower Ob region and adjacent areas of the northern taiga and shrub tundra. About half of the invertebrate species of the study area are northern—mostly hypo- and hemiarctic—tundra species; the rest are boreal and arctomontane-boreal Holarctic and trans-Palearctic species. The anthophilic and aerobiont insect assemblages include many boreal forest forms. A total of 153 species have been observed nesting at the taiga–foresttundra boundary; 81 species have been observed nesting at the tundra–forest-tundra boundary. The avifauna of the forest–tundra becomes enriched with taiga species in floodplain forests and with tundra species on the flat interfluve, in areas of tundra and tundra-like wetlands. The forest–tundra of the Lower Ob region has no avifauna and entomofauna of its own and contains a mixture of taiga and tundra faunas. It has been found that the ecotone effect is not pronounced in the taxonomic composition of birds and insects in the forest–tundra, where only some particular groups (such as amphibiont insects) have increased abundance.     

Radiation effects in wild terrestrial vertebrates - the EPIC collection

The paper presents data on radiation effects in populations of wild vertebrate animals inhabiting contaminated terrestrial ecosystems. The data were extracted from the database "Radiation effects on biota", compiled within the framework of the EC Project EPIC (2000-2003). The data collection, based on publications in Russian, demonstrates radiation effects in the areas characterized with high levels of radionuclides (Kyshtym radioactive trace; "spots" of enhanced natural radioactivity in the Komi region of Russia; territories contaminated from the Chernobyl fallout). The data covers a wide range of exposures from acute accidental irradiation to lifetime exposures at relatively low dose rates. Radiation effects include mortality, changes in reproduction, decrease of health, ecological effects, cytogenetic effects, adaptation to radiation, and others. Peculiarities of radiation effects caused by different radionuclides are described, also the severity of effects as they appear in different organisms (e.g. mice, frogs, birds, etc.).     

Chronic exposure to gamma radiation of wild populations of meadow voles (Microtus pennsylvanicus)

Free-ranging, wild meadow voles (Microtus pennsylvanicus) were exposed to gamma radiation from a (137)Cs irradiator in a series of experiments conducted on six 1-ha meadows within a mixed deciduous forest in Manitoba, Canada. Over a period of 1-1.5 years in each of three experiments, vole populations were monitored with capture-mark-release techniques at nominal exposure rates of 200x, 9000x and 40,000x background. No effects on population or individual characteristics were detected up to the highest exposure rate (81 mGy/d). At this level, third generation voles were monitored up to a lifetime dose of about 5.7 Gy, at a measured dose rate of 44 mGy/d. Smaller numbers of overwintered animals survived and reproduced normally at doses up to 10 Gy. These results are discussed in terms of low-LET, external chronic radiation effects on rodents in the laboratory and the field, relative to current views on appropriate benchmarks for the protection of biota.     

Role of small mammals in natural and anthropogenic landscapes of the right-bank region of Saratov oblast

Small mammal communities inhabiting natural and anthropogenically transformed areas of the right-bank region of Saratov oblast are fairly similar in species composition. They are represented by wide-spread, common species that, against the background of a low population density of typical steppe species, make a major contribution to the community. The highest ecological tolerance is characteristic of the striped field mouse Apodemus agrarius, which is widespread in the study region and dominates in the majority of natural biotopes and in agrocenoses; the common vole Microtus arvalis is scarce in agrocenoses.     

High background radiation areas of Ramsar in Iran: evaluation of DNA damage by alkaline single cell gel electrophoresis (SCGE)

The hot springs in special areas in Ramsar, a northern coastal town in Iran, contain (226)Ra and (222)Rn. The natural radiation effects, radiosensitivity or adaptive responses, on the inhabitants of high natural radiation in Ramsar were studied. The single cell gel electrophoresis was used to monitor DNA damages. Three groups of volunteers were selected, one from high natural background radiation areas as the case group and two from normal background radiation areas as controls (control 1 and control 2). The latter one had the similar living situation to case group while the other (control 2) had different living situation from the other groups. Peripheral blood mononuclear cells (PMNCs) were separated and irradiated by (60)Co source at five different gamma doses. It was found that the spontaneous level of DNA damage and the induced DNA damage in all challenging doses in case group was considerably higher than control groups (p < 0.05). On the other hand, the repair rate in those volunteers, who received less than 10.2 mSv/y was significantly more than the control groups. In the contrary, individuals who live in homes with more than 10.2 mSv/y had incomplete repair. Additionally the plasma and urinary levels of vitamin C were measured spectrophotometrically. Although the concentration of vitamin C of plasma was equal in case and control 1 groups, the urinary level of vitamin C was found to be lower in the case group.     

Species-Specific Features of Inter- and Intrapopulation Variation in the Level of Chromosome Instability in Rodents

Studies on the common vole Microtus arvalis revealed a distinct cytogenetic response to the influence of ionizing radiation, a wide range of variation in the group average indices of chromosome instability beyond the zone of technogenic impact, and the influence of natural factors (viral infections and fluctuations of population size) on the frequency of chromosome aberrations. In the northern mole vole Ellobius talpinus, neither the mutagenic effect of ionizing radiation nor interpopulation differences in the level of chromosome aberrations in the absence of anthropogenic impact were detected. Variation of genome instability of the rodents is significantly contributed to by species demography and population cycles.     

Ecology of the field vole (Microtus agrestis L.) in indigenous and anthropogenic landscapes of Eastern Fennoscandia

The state of the population, biotopic distribution, and population dynamics of the field vole are analyzed on the basis of long-term studies performed in 1956–2012 in taiga ecosystems of Eastern Fennoscandia affected by anthropogenic transformations. General trends and regional and landscape-related specific features of the effects of forest exploitation on the structure of habitats, abundance, and spatial distribution of the field vole are discussed in comparative ecological aspect.     

Migration and biological effect of natural heavy radionuclides on plants

A complex radioecological study of technogenic landscapes of southern Yakutia showed that the main factor responsible for their contamination with uranium and radium is radionuclide dispersal by air with products of rock weathering. Coefficients of biological absorption by plants decrease with an increase in the contamination level, which is explained by the fact that strongly fixed forms of uranium and radium prevail in the contaminated areas. In addition, the root barrier plays an important role. Radiation load is mainly determined by background gamma-radiation. The contribution of internal irradiation accounted for by incorporated radionuclides does not exceed 16% and decreases with an increase in the level of soil contamination. Manchurian alder seeds produced under conditions of enhanced background radiation are more viable than those from the control area. It is shown that seed generations of plants growing under conditions of chronic irradiation are highly resistant to the radiation factor.     

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.     

Uptake of uranium and thorium by native and cultivated plants

Large part of available literature on biogeochemistry of uranium and thorium refers to the studies performed either in highly contaminated areas or in nutrient solutions that have been artificially ‘spiked’ with radionuclides. Effects of background levels of natural radioactivity on soil-grown plants have not been studied to the same extent. In this paper, we summarised results of greenhouse and field experiments performed by the author from 2000 to 2006. We examined some of the factors affecting transfer of U and Th from soil to plants, differences in uptake of these radionuclides by different plants, relationships between U and Th in soil and in plants, and temporal variations of U and Th in different plant species. Concentrations of radionuclides (critical point for experimental studies on biogeochemistry of U and Th - rare trace elements in non-contaminated regions) and essential plant nutrients and trace elements were determined by instrumental neutron activation analysis.