Elevated Radiation Levels Research Articles

Consequences of nuclear accidents for biodiversity and ecosystem services

AbstractNuclear energy is a potential solution to electricity demand but also entails risks. Policy debates on nuclear accidents have focused primarily on negative impacts on humans. Although such impacts are important, we argue that policy debates must also consider the consequences for biodiversity and ecosystem services. We reviewed 521 studies conducted after the Chernobyl accident, the most severe nuclear accident in history. Elevated radiation levels have been recorded among a diversity of species, even up to thousands of kilometers away from the meltdown site, and after more than two decades following the accident. Close to the reactor, physiological and morphological changes have occurred. Negative effects on ecosystem services have been observed, including the contamination of water, soils, and wild food supplies. Informed policy decisions on nuclear energy require a greater understanding of the consequences of accidents, including effects on biodiversity and ecosystem services. Based on our review, we recommend to (1) fully incorporate risks for biodiversity and ecosystem services into policy debates; (2) develop a coherent information chain regarding such risks; (3) use proactive planning strategies to be prepared for potential accidents; and (4) develop a coherent research agenda on the consequences of nuclear accidents for biodiversity and ecosystem services.

Hypothyroidism among former workers of a nuclear weapons facility (Pantex), Amarillo, Texas

ObjectivesIonising radiation can alter thyroid function, and workers at a nuclear weapons facility may be exposed to elevated levels of radiation. The Pantex Plant, located in Amarillo, Texas, is the...

The Use of Photographic Film to Pinpoint Accelerator Beam Losses

Following removal of a superconducting wiggler that has a maximum magnetic-field of 7 T in a high-energy synchrotron facility, sufficient lead shielding was placed upstream of the removal point in the normal-conducting electron storage ring to account for any radiation sources from the upstream components. As is customary in such cases, when vacuum has been breached, there is a period of time required for vacuum re-conditioning of the ring. During this re-conditioning phase, poor vacuum contributes to gas bremsstrahlung formation that typically is visualized as an increase in overall radiation exposure from standard operating conditions. However, in this case, new radiation patterns emerged and persisted throughout the re-commissioning phase. Subsequently, additional shielding was then placed upstream but still failed to resolve the source of radiation. The radiation source point consisted of two distinct components: a point parallel to the position originally covered by the wiggler and a strong forward-directed peak (i.e., bremsstrahlung). The only feedback mechanism to track the beam position is the beam position monitors (BPM's). BPM's were located forward and aft of the parallel source point. The BPM's suggested that the beam was in the correct position. To investigate the elevated radiation level, commercial photographic film was used as a monitoring ruler and the focal point of the radiation source was clearly identified using this novel approach. The silver halide grain contained within the film emulsion possessed sufficient cross section and was activated from Ag to Ag, which has a half-life of 2.39 min and emits easily detectable radiation. Further, the exposed film is ready for reuse after 25 min due to the short half-life of Ag. The proposed method proved to be an easy, economic, and effective approach to rapidly and qualitatively identify the location of the beam losses.

Silicon Detectors for the sLHC

The luminosity upgrade of the Large Hadron Collider (LHC) at CERN to the Super LHC (sLHC) will increase the radiation dose at the experiments by roughly an order of magnitude. The elevated radiation levels require the LHC experiments to upgrade their tracking systems with extremely radiation hard detectors. Recent results on defect characterization of silicon materials and radiation hard technologies developed by the RD50 Collaboration for sLHC use are reported. Studies on n - and p -type silicon with Float Zone (FZ) and Czochralski technologies as well as 3D silicon detector designs are presented. Properties such as charge collection efficiency, electron signal, effective doping concentration (N eff ) and full depletion voltage (V fd ) after radiation exposure are compared to assess the performance of the different technologies.

Growth, assimilate partition and yield of melon charenthais under different shading screens

In this experiment we evaluated the growth, partition of assimilates and yield of melons type hybrid Charenthais 'Fleuron' under different shading nets. The experiment was conducted at Federal University of Viçosa, from November 24, 2003 to March 11, 2004. The treatments consisted of four growth environmental conditions, as follows: control (full sun), and under Aluminet® 30%-O, Cromatinet® 30%-O, Sombrite® 30%, with reduction of photosynthetic active radiation (PAR) of 30.85%, 35.9% and 32.0%, respectively. The experiment was arranged in a complete random design with four replicates. For the periodically evaluated characteristics we used a sub divided parcel 4 x 7 with the growing conditions in the parcel and the evaluations on the sub parcel (0, 14, 28, 42, 56, 70 and 84 days after transplantation). Among the shading nets, overall growth was superior under Aluminet® 30%-O, with similar plant height, length and number of internodes, number of leaves per plant, leaf dry weight, total and commercial yield of fruits and greater leaf area per plant compared to control at full sun. The low number of daily radiation (4.47 hours) and the good growth and yield of the melon when shaded by 30.85% with Aluminet® 30%-O, are indicatives that this culture does not require elevated levels of radiation as mentioned before. The growth of melon under partial restriction of light is promising, opening opportunities to production in new environments as agroforestry systems and associated cultivations.

Elevated Ultraviolet-B Radiation Reduces Concentrations of Isoflavones and Phenolic Compounds in Soybean Seeds

The gradual disruption of the ozone layer in the stratosphere has resulted in increased exposure of plants to ultraviolet-B (UV-B, 280–315 nm) radiation. UV-B radiation is known to affect crop growth and quality negatively. A study was conducted to determine the impact of elevated UV-B radiation levels on the isoflavones and phenolic compound concentrations of seven soybean varieties. UV-B radiation significantly reduced the concentration of most isoflavones and phenolic compounds in soybean seeds. Exposure to elevated UV-B levels overall resulted in 35 % reduction in total isoflavones and 31 % in phenolic compounds concentrations. The effect on individual isoflavones and phenolic compounds depended on the compound and variety, but UV-B overwhelmingly reduced concentrations. This study suggests that increased UV-B radiation negatively impacted soybean quality by reducing the concentration of compounds that have health-beneficial properties.

Long-term effects of elevated UV-B radiation on photosynthesis and ultrastructure of Eriophorum russeolum and Warnstorfia exannulata

The depletion of stratospheric ozone above the Arctic regions may increase the amount of UV-B radiation to which the northern ecosystems are exposed. In this paper, we examine the hypothesis that supplemental UV-B radiation may affect the growth rate and photosynthesis of boreal peatland plants and could thereby affect the carbon uptake of these ecosystems. In this study, we report the effects of 3-year exposure to elevated UV-B radiation (46% above ambient) on the photosynthetic performance and ultrastructure of a boreal sedge Eriophorum russeolum and a moss Warnstorfia exannulata. The experiment was conducted on a natural fen ecosystem at Sodankylä in northern Finland. The effects of UV-B radiation on the light response of E. russeolum CO 2 assimilation and the maximal photochemical efficiency of photosystem II in a dark-adapted state ( F v/ F m) were measured in the field. In addition, the effect of supplemental UV-B radiation on organelles of photosynthetic cells was studied by electron microscopy. The UV-B treatment had no effect on the CO 2 assimilation rate of either species, nor did it affect the structure of the cell organelles. On chlorophyll fluorescence, the UV-B exposure had only a temporary effect during the third exposure year. Our results suggested that in a natural ecosystem, even long-term exposure to reasonably elevated UV-B radiation levels does not affect the photosynthesis of peatland plants.

Solar Radiation Induces Non-Nuclear Perturbations and a False Start to Regulated Exocytosis in Cryptosporidium parvum

Stratospheric ozone depletion, climate warming and acidification of aquatic ecosystems have resulted in elevated levels of solar radiation reaching many aquatic environments with an increased deleterious impact on a wide range of living organisms. While detrimental effects on living organisms are thought to occur primarily through DNA damage, solar UV can also damage cellular proteins, lipids and signalling pathways. Cryptosporidium, a member of the eukaryotic phylum Apicomplexa, contain numerous vesicular secretory organelles and their discharge via regulated exocytosis is essential for the successful establishment of infection. Using flow cytometric techniques we demonstrate that solar UV rapidly induces sporozoite exocytosis resulting in a significant reduction in the ability of sporozoites to attach and invade host cells. We found that solar UV induced sporozoite membrane depolarization, resulting in reduced cellular ATP and increased cytosolic calcium. These changes were accompanied by a reduction in the internal granularity of sporozoites, indicative of apical organelle discharge, which was confirmed by analysis of sporozoites with an exocytosis-sensitive dye. The precise timing of apical organelle discharge in the presence of a compatible host cell is critical for sporozoite attachment and invasion. Our results demonstrate for the first time how solar UV radiation can interfere with exocytosis, a fundamental cellular process in all eukaryotic cells. We contend that not only may the forecast increases in solar radiation in both aquatic and terrestrial environments significantly affect members of the Apicomplexa, solar UV-induced membrane depolarizations resulting in cytosolic calcium perturbation may affect a wider range of eukaryotic organisms through antagonistic effects on a myriad of calcium dependant cellular functions.

Silicon detectors for the super LHC

The luminosity upgrade of the Large Hadron Collider (LHC) at CERN to the Super LHC (sLHC) will increase the radiation dose at the experiments by roughly an order of magnitude. The elevated radiation levels require the LHC experiments to upgrade their tracking systems with extremely radiation hard detectors, capable of withstanding about a 1-MeV neutron-equivalent (n eq) fluence of 10 16 per square centimeter for the innermost tracking layers. Recent results on radiation hardening technologies developed by the RD50 Collaboration for sLHC use are reported. Silicon detectors have been designed and produced on n- and p-type wafers made by float zone, epitaxial and Czochralski technologies. Their charge collection efficiency after proton, neutron, pion, and mixed irradiation to sLHC fluences has been studied. Novel detector concepts have been designed, produced, and tested as well. Radiation-induced microscopic defects have been investigated and can be partly linked to the performance degradation of irradiated detectors.

First steps towards a European atlas of natural radiation: status of the European indoor radon map

Within the context of its institutional scientific support to the European Commission, in 2005 the Radioactivity Environmental Monitoring (REM) group at the Joint Research Centre of the European Commission, started to explore the possibility of mapping indoor radon in European houses as a first step towards preparing a European Atlas of Natural Radiations. The main objective of such an atlas is to contribute to familiarizing the public with its naturally radioactive environment. The process of preparing the atlas should also provide the scientific community with a database of information that can be used for further studies and for highlighting regions with elevated levels of natural radiation. This document presents the status of the European indoor radon (Rn) map, first statistical results, and outlines of forthcoming challenges.

Development of historical exposure estimates of cosmic radiation and circadian rhythm disruption for cohort studies of Pan Am flight attendants

The National Institute for Occupational Safety and Health is conducting cohort studies of flight crew employed by the former Pan American World Airways company (Pan Am) as part of an effort to examine flight crew workplace exposures and health effects. Flight crew are exposed to elevated levels of cosmic radiation and to disruption of circadian rhythm when flying across multiple time zones. Methods exist to calculate cosmic radiation effective doses on individual flights; however, only work histories which provided an employee's domicile (home base) history rather than a record of every flight flown were available. We developed a method for estimating individual cumulative domicile-based cosmic radiation effective doses and two metrics for circadian rhythm disruption for each flight attendant: cumulative times zones crossed and cumulative travel time during the standard sleep interval. The domicile-exposure matrix developed was used to calculate exposure estimates for a cohort mortality study of former Pan Am flight attendants.

Mrad9 and Atm Haploinsufficiency Enhance Spontaneous and X-Ray-Induced Cataractogenesis in Mice

Rad9 and Atm regulate multiple cellular responses to DNA damage, including cell cycle checkpoints, DNA repair and apoptosis. However, the impact of dual heterozygosity for Atm and Rad9 is unknown. Using 50 cGy of X rays as an environmental insult and cataractogenesis as an end point, this study examined the effect of heterozygosity for one or both genes in mice. Posterior subcapsular cataracts, characteristic of radiation exposure, developed earlier in X-irradiated double heterozygotes than in single heterozygotes, which were more prone to cataractogenesis than wild-type controls. Cataract onset time and progression in single or double heterozygotes were accelerated even in unirradiated eyes. These findings indicate that the cataractogenic effect of combined heterozygosity is greater than for each gene alone and are the first to demonstrate the impact of multiple haploinsufficiency on radiation effects in an intact mammal. These observations may help explain observed interindividual differential radiosensitivity in human populations and have important implications for those undergoing radiotherapy or exposed to elevated levels of cosmic radiation, such as the astronaut corps. These findings demonstrate that Mrad9 and Atm are important determinants of lens opacification and, given the roles of Atm and Rad9 in maintaining genomic stability, are consistent with a genotoxic basis for radiation cataractogenesis.

Radiation-resistant erbium-doped silica fibre

It is shown that the service life of erbium-doped fibres can be increased many times under conditions of an elevated radiation level by loading the fibre glass network with molecular hydrogen. Backdiffusion of hydrogen from the fibre in the process of its operation is virtually excluded for the fibre covered with a hermetic carbon coating. It is shown that this technique of fibre preparation allows one to slow down significantly degradation of the lasing properties of erbium fibres under the conditions characteristic of space applications.

Spatial Distribution of Orofacial Cleft Defect Births in Harris County, Texas, 1990 to 1994, and Historical Evidence for the Presence of Low-level Radioactivity in Tap Water

While both ionizing and nonionizing radiation are known to impair human reproductive capacity, the role of low-level domestic radiation continues to be an unsettled issue. We examined the geostatistical distribution (residential longitude and latitude) of orofacial cleft birth cases adjusted for the underlying population distribution. Furthermore, we examined the cleft birth rates enumerated by zip codes for possible associations with levels of radium and radon in drinking water. Cleft births and unaffected live births in Harris County, Texas, from 1990 to 1994, were geocoded by residential addresses and tested for spatial clusters using the space-time clustering program SaTScan. Historical sample data on local variations in water quality facilitated the assessment of the association of orofacial cleft defect births with low-level radiation exposure. A cluster of significantly greater than expected numbers of cleft defect births was identified in northwest Harris County, (relative risk = 3.0, P = 0.043), where the presence of elevated levels of radium (> 3 pCi/L) and radon (> 300 pCi/L) in the tap water has been known since the 1980s. Despite the ecological design of the study, lacking individual exposure measurements for cleft birth residences, there was strong suggestive evidence of an association between elevated radiation levels in tap water and elevated cleft birth prevalence rates by zip codes. Attention of physicians is invited to environmental causes as potential risk factors for orofacial cleft. This would aid in genetic counseling and the development of future preventive measures.

Joint Effects of Elevated Levels of Ultraviolet-B Radiation, Carbon Dioxide and Ozone on Plants¶†

There is growing interest regarding the joint effects of elevated levels of surface ultraviolet B (UV-B) radiation, carbon dioxide (CO2) and ozone (O3) on plants. Our current knowledge of this subject is too limited to draw any specific conclusions, although one might state that such effects are likely to be highly species dependent and may be more than additive, additive or less than additive. There are a number of uncertainties associated with the experimental protocols used and the conclusions reached in many studies. Nevertheless, in North America, there appear to be genotypes of three monocot crop species (Avena sativa L., Oryza sativa L. and Sorghum vulgare L.); six dicot crops (Cucumis sativus L., Lactuca sativa L., Lycopersicon esculentum Mill., Phaseolus vulgaris L., Pisum sativum L. and Solanum tuberosum L.) and two conifer species (Pinus ponderosa Dougl. and Pinus taeda L.) that may be considered sensitive to the joint effects of elevated levels of UV-B, CO2 and O3. However, to provide a more reliable assessment or validation of the predictions, future research must consider the concept of plant response surfaces and describe them more fully in numerical terms. Achieving that objective will require close cooperation among a number of scientists representing geographic locations with known spatial and temporal differences in UV-B, CO2 and O3 to conduct experiments under their site-specific conditions, using common plant materials and experimental protocols.

Instrumental neutron activation analysis for the elemental analysis of cement

Cement is widely used as a construction material in Libya. Production plants introduce certain contaminants to the environment. The dust from such plants is carried away to neighbouring areas. This dust contains a substantial amount of contaminants depending on the origin of clays used in the production. In this study, a survey of elemental concentration of clay and cement was carried out to assess the environmental impact of such plants, especially those that are situated near residential and agricultural areas. Cement and clay samples, imported and locally produced, were analyzed. Instrumental neutron activation analysis was utilized to determine the elemental concentration of As, Ca, Ce, Co, Cr, Eu, Fe, Hf, La, Na, Rb, Sb, Sc, Sm, Ta, Th, U, Yb and Zn. Elevated concentrations of U and Th were found in a number of cement samples. The two nuclides are part of an elaborate decay scheme producing a range of radioactive elements, which emit alpha-, beta- and gamma-radiation. With 40K, they could give elevated levels of background radiation in buildings resulting in higher exposure doses. This could pose a health hazard and a detrimental effect on the well being of residents, especially in poor ventillated buildings. Also, cement is the main component for constructing underground reservoirs for collecting rainwater for drinking in private residences, so some harmful elements could leach into water. This is the first comprehensive survey of commercial cement brands and clays used in Libya. These results are intended to build a database for trace element concentrations using INAA.

‘Chlorophyll-like’ compounds as novel biomarkers of stress in corals

The appearance of 'bleached' or pale-coloured corals at numerous locations around the world over the last 3 decades has been linked to various environmental stressors. However, the role and fate of zooxanthellar pigments in response to such stress has received little attention. We provide new insights into the adaptive response of coral zooxanthellae to environmental stress, based upon the analysis of chlorophyll pigments using high performance liquid chromatography. Manipulative field experiments were used to monitor induction and recovery of the reef coral Goniastrea aspera from photo-damage. Over a 6 d period the production of up to 6 compounds with very similar light absorbance spectra to chlorophyll a (chl a) was observed. Higher concentrations of a sub-set of these products were observed in response to elevated solar radiation levels. The fact that the same chl a-like compounds were consistently observed under the same experimental conditions means that they may have significant potential as biomarkers of stress in corals and may also provide a means of 'fingerprinting' environmental stress in corals.

Transcriptional profiling of summer wheat, grown under different realistic UV-B irradiation regimes

There is limited information on the impact of present-day ultraviolet-B (UV-B) radiation on a reprogramming of gene expression in crops. Summer wheat was cultivated in controlled environmental facilities under simulated realistic climatic conditions. We investigated the effect of different regimes of UV-B radiation on summer wheat (Triticum aestivum L.) cultivars Nandu, Star and Turbo. Until recently, these were most important in Bavaria. Different cultivars of crops often show great differences in their sensitivity towards UV-B radiation. To identify genes that might be involved in UV-B defence mechanisms, we first analyzed selected genes known to be involved in plant defence mechanisms. RNA gel blot analysis of RNA isolated from the flag leaf of 84-day-old plants showed differences in transcript levels among the cultivars. Flag leaves are known to be important for grain development, which was completed at 84 days post-anthesis. Catalase 2 (Cat2) transcripts were elevated by increased UV irradiation in all cultivars with highest levels in cv. Nandu. Pathogenesis-related protein 1 (PR1) transcripts were elevated only in cv. Star. A minor influence on transcripts for phenylalanine ammonia-lyase (PAL) was observed in all three cultivars. This indicates different levels of acclimation to UV-B radiation in the wheat cultivars studied. To analyze these responses in more detail, UV-B-exposed flag leaves of 84-day-old wheat (cv. Nandu) were pooled to isolate cDNAs of induced genes by suppression-subtractive hybridization (SSH). Among the initially isolated cDNA clones, 13 were verified by RNA gel blot analysis showing an up-regulation at elevated levels of UV-B radiation. Functional classification revealed genes encoding proteins associated with protein assembly, chaperonins, programmed cell death and signal transduction. We also studied growth, flowering time, ear development and yield as more typical agricultural parameters. Plant growth of young plants was reduced at increased UV-B radiation. Flowering and ear development were delayed concomitantly, whereas total grain weight was not influenced at any of the UV-B irradiation regimes.

Cancer incidence in areas with elevated levels of natural radiation

It has been reported that on reaching a certain level of cell damage the production of repair enzymes is triggered which decreases the chromosome aberrations. If this happens, prolonged exposure to high levels of natural radiation in areas with elevated levels of background radiation could decrease the frequency of chromosome aberrations. Recent epidemiological studies indicated that there is an increased risk of cancer in healthy individuals with high levels of chromosomal aberrations. Studies performed in Nordic countries as well as Italy, showed that increased levels of chromosome aberrations in lymphocytes can be used to predict cancer risk in humans. One may conclude that a dose of ionising radiation sufficient to produce a certain level of cell damage increases production of antioxidants and repair enzymes that decrease either the frequency of chromosome aberrations or the cancer risk. People in some areas of Ramsar, a city in northern Iran, receive an annual radiation dose from background radiation that is more than five times higher than the 20 mSv. Yr-1 that is permitted for radiation workers. Inhabitants of Ramsar have lived for many generations in these high background areas. If an annual radiation dose of a few hundred mSv is detrimental to health, causing genetic abnormalities or an increased risk of cancer, it should be evident in these people. The absorbed dose rate in some high background radiation areas of Ramsar is approximately 55-200 times higher than that of the average global dose rate. It has been reported that 3–8% of all cancers are caused by current levels of ionising radiation. If this estimation were true, all the inhabitants of such an area with extraordinary elevated levels of natural radiation would have died of cancer. Our cytogenetic studies show no significant differences between people in the high background area compared to people in normal background areas. As there was no increased level of chromosome aberrations, it may be predicted that the cancer incidence is not higher than in the neighbouring areas with a normal background radiation level. Although there is not yet solid epidemiological information, most local physicians in Ramsar report anecdotally that there is no increase in the incidence rates of cancer or leukemia in their area. There are no data to indicate a significant increase of cancer incidence in other high background radiation areas (HBRAs). Furthermore, several studies show a significant decrease of cancer death rates in areas with high backgrounds. It can be concluded that prolonged exposure to high levels of natural radiation possibly triggers processes such as the production of antioxidants and repair enzymes, which decreases the frequency of chromosome aberrations and the cancer incidence rate.

NORM Contamination—Now You See It, Now You Don’t

Contamination from naturally occurring radioactive material on the inside of piping or tanks in refineries can usually be easily detected from the outside by external gamma measurements with simple count rate meters or more complicated gamma spectroscopy instruments. Usually, such contamination is from radium in equilibrium with its progeny. A number of different gamma rays are emitted by this mix. However, due to certain processes or circumstances, a significant amount of NORM can be present without the characteristic gamma signature of radium and its progeny. The process of cracking low molecular weight hydrocarbon gases from crude oil allows radon through but leaves radium behind. The radon enters the process piping and decays, depositing its short-lived decay products or progeny. When the short-lived progeny decay, all that is left are alpha and beta emitters. When this occurs, measurements taken on the outside of piping indicate no elevated levels of gamma radiation; however, elevated levels of alpha and beta radiation can be detected on the inside of the piping. 210Pb is usually the only gamma emitter detected on the inside of the piping and, its gamma ray energy is such that little if any penetrates the walls of the piping. Since one of the release criterion for piping material is an external dose rate of less than 50 microR h(-1), it is possible that a survey from the outside of the piping can be negative when, in fact, thee can be appreciable contamination on the inside of the piping.