Environmental Radiation Exposure Research Articles

Double-strand break motions shift radiation risk notions?

The key biologic hazard of ionizing radiation is damage to cellular DNA. Although DNA damage has long been studied in radiotherapeutic research as a means to kill cancer cells, it is also of interest to NASA's Space Radiation Program (1), which seeks to understand radiobiological risks to astronauts posed by cosmic radiation. Closer to home, DNA damage is also a focus of the US Department of Energy Low Dose Research Program, whose overall goal is to support biological research aimed at assessing risks posed by workplace, waste cleanup, and environmental radiation exposures (2). Such risks are obviously a direct public concern as well, no doubt heightened in the wake of the Fukushima Daiichi nuclear plant incident (3). In PNAS (4), Neumaier et al. revisit common imaging-based methods used to assess cellular DNA damage from radiation exposure, and show how standard interpretation of those assays may be flawed. In the process, this study glimpses a DNA damage management dynamic that, if borne out in further study, stands to revise our understanding of damage repair in mammalian cells.

Radiation Treatment for Localized Prostate Cancer and the Risk of Developing Myelodysplastic Syndromes (MDS)

Abstract 120 Background:Both environmental radiation exposure and use of therapeutic radiation (XRT) in primary solid tumor malignancies increase the risk of secondary MDS. No data exist on the risk of developing secondary MDS in prostate cancer patients (pts) being treated with radiotherapy. Establishing this risk has important clinical implications, as prostate cancer is the leading cancer in men and radiation therapy has increasingly become the preferred modality for treatment of localized prostate cancer. Methods:We performed a prospective case control study of 11,015 pts with localized prostate adenocarcinoma newly diagnosed between 1986 and 2011 at Cleveland Clinic who underwent treatment with either radical prostatectomy (control group) or definitive radiotherapy (external beam radiotherapy [EBRT] or prostate interstitial brachytherapy [PI] – case group), to investigate the risk of radiation-related MDS. Data on demographics, surgery, radiation treatment, and follow-up were collected from merged prostate cancer and MDS databases. Cytogenetic risk groups were per International Prognostic Scoring System (IPSS) for MDS. Univariate and multivariate analyses were performed using the Fine and Gray competing risk model with MDS as a time-dependent endpoint (which incorporates differences in duration of follow-up) and death from any cause as the competing event, comparing radiotherapy groups to the surgical cohort as the reference group, controlling for age and follow-up frequency. Hazard ratios (HR) with 95% confidence intervals (CIs) are reported. Results:For all pts, median age was 64 years (yrs, range, 37 – 88) at the time of prostate cancer diagnosis: 69 yrs in EBRT, 67 yrs in PI, and 60 yrs in surgery pts, respectively (p<0.0001); 5119 (46%) were treated with XRT, 5896 (54%) with prostatectomy. None of the pts had a previous history of another malignancy. Among XRT pts, 2183 (43%) were treated with EBRT, 2936 (57%) with PI. Median follow-up was 3.0 yrs [(range, 0.0 – 25.2): 6.8 yrs in the EBRT group, 2.5 yrs in the PI group and 1.8 yrs in the surgery group, (p<0.0001)] following prostate intervention, longer (4.6 yrs) in pts treated since 1996, when PI was first performed [6.6 yrs in the EBRT group, 3.8 yrs in the PI group and 4.3 yrs in the surgery group, (p<0.0001)]. In the entire cohort, 30 pts developed MDS: 24 in the XRT group and 6 in the surgery group. MDS World Health Organization classification was: RA/RARS (n=12), RCMD (n=3), RAEB-1 (n=3), RAEB-2 (n=3), CMML (n=2), MDS-U (n=3) and unknown (n=4). IPSS cytogenetic risk classification was: good risk (n=17), intermediate risk (n=5), poor risk (n= 4) and unknown (n = 4). For MDS pts within the XRT group, median age at MDS diagnosis was 79 yrs (range, 74 – 89) for EBRT, 80 yrs (range, 64 – 100) for PI. The median time to develop MDS was 8.9 yrs (range, 0.9 – 20.2): 9.1 for EBRT, 8.2 for PI, and 13.0 for prostatectomy pts, respectively (p=0.05). In univariate analyses, older pts (HR=1.14; CI, 1.09 – 1.2; p<0.0001), and those treated with XRT (HR=3.3; CI, 1.35 – 8.08; p=0.009): EBRT (HR=2.6; CI, 1.0 – 6.9; p=0.05), PI (HR=5.87; CI, 2.1 – 16.3; p=0.0007) were significantly more likely to develop MDS. In multivariate analysis though, while advanced age (HR=1.13; CI, 1.0 – 1.2; p < 0.0001) remained significantly associated with MDS development, XRT did not (HR=1.56; CI, 0.56 – 4.38; p=0.4), though a trend remained for PI (HR=2.85; CI, 0.9 – 8.8; p = 0.07). Conclusions:Pts who underwent definitive radiation treatment for localized prostate cancer did not appear to have a significantly increased risk of subsequent MDS, in analyses that controlled for age and incorporated length of follow-up. A trend for MDS development was present for those undergoing XRT with PI. These findings are encouraging for both patients and providers who have concerns about the potential effects of XRT on development of MDS. Disclosures:Maciejewski:Celgene: Membership on an entity's Board of Directors or advisory committees. Sekeres:Celgene: Consultancy, Honoraria, Speakers Bureau.

Radioactivity Levels and Health Risks due to Radionuclides in the Soil of Yalova, Northwestern Turkey

Naturally occurring radionuclide of terrestrial origin (also called primordial radionuclide) are present in various degrees in all media in the environment, including the human body itself. Their concentrations in environment decrease continually by decaying. The main objective of this study is to evaluate the radioactivity levels and health risks due to terrestrial radionuclide in soil of Yalova, northwestern Turkey. For this purpose, activity concentrations of radionuclide in soil and the environmental outdoor gamma dose rates (terrestrial and cosmic) have been investigated in the city of Yalova. In addition, maps for the radionuclide activity concentrations of soil and the outdoor gamma dose rates distributions have been plotted for the region. The average activities of radionuclide, 238 U, 232 Th, 226 Ra, 40 K, and 137 Cs in the soil were determined as 17.95 (8.5-37.3) Bq/kg, 26.87 (3.8-43.9) Bq/kg, 22.36 (8.3-41) Bq/kg, 419.32 (197.1-950.0) Bq/kg, 2.53 (0.5-13.4) Bq/kg, respectively, in the region. The average outdoor gamma dose rates due to terrestrial and cosmic radiations were found to be 49 nGy/h and 35 nGy/h with the total of 84 nGy/h outdoor gamma exposure rate in the region. Annual effective dose due to environmental outdoor gamma radiation exposures was determined as 103 nSv with the excess lifetime cancer risk of 0.042 x 10 -2 in the region. The results of the study were discussed with the studies done in the close cities and the worldwide averages.

Allelic Imbalances in Radiation—Associated Acute Myeloid Leukemia

Acute myeloid leukemia (AML) can develop as a secondary malignancy following radiotherapy, but also following low-dose environmental or occupational radiation exposure. Therapy-related AML frequently carries deletions of chromosome 5q and/or 7, but for low-dose exposure associated AML this has not been described. For the present study we performed genome-wide screens for loss-of-heterozygosity (LOH) in a set of 19 AML cases that developed after radiation-exposure following the Chernobyl accident. Using Affymetrix SNP arrays we found large regions of LOH in 16 of the cases. Eight cases (42%) demonstrated LOH at 5q and/or 7, which is a known marker of complex karyotypic changes and poor prognosis. We could show here for the first time that exposure to low-dose ionizing radiation induces AML with molecular alterations similar to those seen in therapy-related cases.

Outdoor radioactivity and health risks in Balikesir, northwestern Turkey

External irradiation from radionuclides naturally present in the environment or released from man-made practices or events is usually an important component of the exposure of human populations. These exposures derive primarily from gamma radiation arising from the decay of these radionuclides at locations outside the human body. The main objective of this study is to evaluate the radioactivity levels and health risks due to terrestrial radionuclides in the soil of Balikesir, one of the largest cities of the country, northwestern Turkey. For this purpose, activity concentrations of radionuclides in soil and outdoor gamma dose rates (terrestrial and cosmic) have been investigated in the city of Balikesir. In addition, maps for the radionuclide activity concentrations of soil and the outdoor gamma dose rate distributions have been plotted for the region. The average activities of radionuclides, (238)U, (232)Th, (40)K, (235)U and (137)Cs in the soil were determined to be 37.6 ± 10.8, 54.7 ± 15.1, 674.5 ± 203.2, 3.6 ± 1.6, 3.4 ± 2.2 Bq kg(-1), respectively, in the region. The average outdoor gamma dose rates due to terrestrial and cosmic radiations were found to be 78.5 ± 12.4 and 48.9 ± 5.8 nGy h(-1) with the total of 127.4 ± 18.9 nGy h(-1) in the region. Annual effective dose due to environmental outdoor gamma radiation exposures was determined to be 156.3 nSv. The mean estimated cancer risk values were found to be 0.063 × 10(-2) for the region using risk factors of ICRP 103. The results of the study were discussed with the studies done in other cities of Turkey and the worldwide averages.

Micronuclei in neonates and children: effects of environmental, genetic, demographic and disease variables

Children may be more susceptible to the effects of the environmental exposure and medical treatments than adults; however, limited information is available about the differences in genotoxic effects in children by age, sex and health status. Micronucleus (MN) assay is a well established method of monitoring genotoxicity, and this approach is thoroughly validated for adult lymphocytes by the Human Micronucleus Biomonitoring project (HUMN.org). Similar international undertaking is in progress for exfoliated buccal cells. Most of the MN studies in children are focused on analyses of lymphocytes but in the recent years, more investigators are interested in using exfoliated cells from the oral cavity and other cell types that can be collected non-invasively, which is particularly important in paediatric cohorts. The baseline MN frequency is relatively low in newborns and its assessment requires large cohorts and cell sample counts. Available results are mostly consistent in conclusion that environmental pollutants and radiation exposures lead to the increase in the MN frequency in children. Effects of medical treatments are less clear, and more studies are needed to optimise the doses and minimise genotoxicity without compromising therapy outcomes. Despite the recent progress in MN assay in children, more studies are warranted to establish the relationship between MN in lymphocytes and exfoliated cells, to clarify sex, age and genotype differences in baseline MN levels and the changes in response to genotoxicants. One of the most important types of MN studies in children are prospective cohorts that will help to clarify the predictive value of MN and other cytome end points for cancer and other chronic diseases of childhood and adulthood. Emerging 'omic' and other novel molecular technologies may shed light on the molecular mechanisms and biological pathways associated with the MN levels in children.

Improved Survival and Recovery of Hematopoiesis Following Lethal Radiation by Chloroquine-Mediated Activation of ATM

AbstractAbstract 2228Irreversible bone marrow damage and impaired blood formation is the primary cause of death following exposure to high doses of radiation. Moreover, the rate at which radiation is delivered may have a profound impact on cytotoxicity; prolonged exposure at a low dose-rate (LDR; 9.4 cGy/hr) has been found to induce greater cell death than the same total dose given at a high dose-rate (HDR; 4500 cGy/hr). Few non-toxic agents are presently available that can offer substantial protection against radiation induced bone marrow failure and death, especially during LDR exposure. We previously demonstrated that chloroquine, a commonly used agent in the treatment of malaria and rheumatologic diseases, can prevent LDR radiation induced cytotoxicity of cell lines in vitro and studied its effects on hematopoiesis in vivo. We initially quantified the effects of LDR radiation on C57/B6 mice and found that 9 Gy delivered at 9.4 cGy/hr for 95.7 hrs induced death in 13/19 (68%) of animals at 15–35 days after radiation. The administration of syngeneic bone marrow cells (1 × 106 cells) immediately after LDR radiation completely rescued animals (10/10) demonstrating that bone marrow failure was responsible for LDR radiation induced death similar to HDR radiation. Next we treated mice with chloroquine (0.0594 mg/17g body weight, i.p.) 24 hrs and 4 hrs prior to exposure to LDR radiation and found that it significantly improved survival (80%, p < 0.05) compared to untreated animals exposed to LDR radiation (32%). We examined hematopoietic recovery following LDR radiation and found that the peripheral WBC was significantly greater in mice treated receiving chloroquine (3.4 × 106/ml vs 1.1 × 106/ml at day 16, p<0.05). Similarly, we found that in vivo chloroquine treatment significantly increased the recovery of bone marrow myeloid CFC (p=0.02), suggesting that it impacted myeloid progenitors. To further validate this finding, we transplanted bone marrow from LDR irradiated mice into lethally irradiated CD45 congenic recipient mice, and found a significant improvement in early engraftment (4.2% vs. 0.4% engraftment at 6 weeks post-transplant, p=0.015). Chloroquine has been found to protect cancer cell lines from LDR radiation in vitro by activating ATM, an essential DNA damage sensor. We examined the effect of chloroquine on ATM and treated unradiated lin- bone marrow cells with chloroquine in vitro (35 ug/ml, 2 hr). Compared to control cells, chloroquine treated cells expressed 2.5-fold more phosphorylated ATM suggesting that the activation of ATM by chloroquine abrogated the lethal effects of LDR radiation in hematopoietic progenitors. We confirmed that ATM was required for chloroquine-mediated radioprotection by studying ATM null mice. In contrast to wild type mice, chloroquine treatment failed to protect ATM null mice from LDR radiation (9 Gy total) with 8/13 (62%) and 9/13 (69%) of animals surviving in treated or non treated mice, respectively (p=0.86). These data suggest that chloroquine exerts a radioprotective effect from LDR radiation by activating ATM in vivo, and may represent a novel means of limiting acute bone marrow failure in the event of widespread environmental LDR radiation exposure. Disclosures:Matsui: Pfizer: Consultancy; Bristol-Meyers Squibb: Consultancy; Infinity Phamaceuticals: Consultancy, Patents & Royalties; Merck: Consultancy, Research Funding; Geron Corporation: Research Funding.

Mechanism of genotoxicity induced by targeted cytoplasmic irradiation

Background:Direct damage to DNA is generally accepted as the main initiator of mutation and cancer induced by environmental carcinogens or ionising radiation. However, there is accumulating evidence suggesting that extracellular/extranuclear targets may also have a key role in mediating the genotoxic effects of ionising radiation. As the possibility of a particle traversal through the cytoplasm is much higher than through the nuclei in environmental radiation exposure, the contribution to genotoxic damage from cytoplasmic irradiation should not be ignored in radiation risk estimation. Although targeted cytoplasmic irradiation has been shown to induce mutations in mammalian cells, the precise mechanism(s) underlying the mutagenic process is largely unknown.Methods:A microbeam that can target the cytoplasm of cells with high precision was used to study mechanisms involved in mediating the genotoxic effects in irradiated human–hamster hybrid (AL) cells.Results:Targeted cytoplasmic irradiation induces oxidative DNA damages and reactive nitrogen species (RNS) in AL cells. Lipid peroxidation, as determined by the induction of 4-hydroxynonenal was enhanced in irradiated cells, which could be suppressed by butylated hydroxyl toluene treatment. Moreover, cytoplasmic irradiation of AL cells increased expression of cyclooxygenase-2 (COX-2) and activation of extracellular signal-related kinase (ERK) pathway.Conclusion:We herein proposed a possible signalling pathway involving reactive oxygen/nitrogen species and COX-2 in the cytoplasmic irradiation-induced genotoxicity effect.

Epidemiological Studies of Cataract Risk at Low to Moderate Radiation Doses: (Not) Seeing is Believing

The prevailing belief for some decades has been that human radiation-related cataract occurs only after relatively high doses; for instance, the ICRP estimates that brief exposures of at least 0.5-2 Sv are required to cause detectable lens opacities and 5 Sv for vision-impairing cataracts. For protracted exposures, the ICRP estimates the corresponding dose thresholds as 5 Sv and 8 Sv, respectively. However, several studies, especially in the last decade, indicate that radiation-associated opacities occur at much lower doses. Several studies suggest that medical or environmental radiation exposure to the lens confers risk of opacities at doses well under 1 Sv. Among Japanese A-bomb survivors, risks for cataracts necessitating lens surgery were seen at doses under 1 Gy. The confidence interval on the A-bomb dose threshold for cataract surgery prevalence indicated that the data are compatible with a dose threshold ranging from none up to only 0.8 Gy, similar to the dose threshold for minor opacities seen among Chernobyl clean-up workers with primarily protracted exposures. Findings from various studies indicate that radiation risk estimates are probably not due to confounding by other cataract risk factors and that risk is seen after both childhood and adult exposures. The recent data are instigating reassessments of guidelines by various radiation protection bodies regarding permissible levels of radiation to the eye. Among the future epidemiological research directions, the most important research need is for adequate studies of vision-impairing cataract after protracted radiation exposure.

핵의학과에서 환경방사선량 측정에 대한 연구

국내의 경우 방사선작업종사자의 개인피폭관리는 선량한도를 초과한 피폭의 유무를 확인하여 사후 조치를 취하는 것에 초점이 맞추어져 있다. 그러나 의료기관 핵의학과의 경우 개봉선원을 사용하므로 작업환경이 방사선에 노출될 가능성이 많고, 방사성의약품 투여 후 수 시간 혹은 수 일 동안은 환자 자체가 방사선원이 되므로 방사선작업종사자나 수시출입자, 환자보호자들의 방사선 피폭 가능성이 매우 높다. 따라서 환자보호자 등 일반출입자의 방사선피폭을 방지하기 위해서는 환경방사선관리가 적절하게 실시되어야 한다. 일본에서는 "방사성동위원소등에 의한 방사선장해의 방지에 관한 법률" 등에 근거하여 방사선작업환경에 대한 환경방사선량을 정기적으로 측정, 보관하도록 하고 있다. 이에 대전시 소재 대학병원 핵의학과에서 일본에서 시행하고 있는 것과 같은 방법으로 핵의학과 내 8개소에 유리선량계를 설치하여 환경방사선을 측정한 결과 8개소 모두 "진단용 방사선 발생장치의 안전관리에 관한 규칙"에 규정된 방사선구역의 외부방사선량인 주당 0.3 mSv에는 훨씬 미치지 못하는 적은 선량이 측정되었다. 그러나 접수대에서는 3개월 누계 선량률이 0.51 mSv로서 접수대 종사자는 일반인 연간 유효선량한도인 1 mSv를 초과할 가능성이 높았으며, 환자 및 보호자 대기실에서도 0.23 mSv(3개월 누계치 0.69mSv)가 측정되어 유리선량계를 설치한 8개소 가운데 가장 높은 선량률을 보였다. 이것은 일반인의 연간 유효선량한도인 1 mSv를 초과하는 값이며, "방사선방호 등에 관한 기준 고시"에 환경상 위해방지를 위해 규정된 연간 유효선량 0.25 mSv를 초과하는 값이다. 따라서 접수대 근무자, 환자보호자 및 제3자 보호를 위해 핵의학과 내 환경방사선량 감소를 위한 적극적인 대책이 필요한 것으로 나타났다. Korean individual occupational exposure control is focused on the retrospective service to the over-exposed person by the reading of personal dosimeter. Since the radiophamaceuticals using in the nuclear medicine department are uncontained radiation sources, the potential exposure at working environment is very high. Moreover, a patient remains radioactive for hours or even days after the administration of a radiopharmaceutical for diagnosis or treatment. Thus, the proper working environmental exposure control must be established and executed to protect not only the affiliated employees, but also guardians accompanying patients and temporarily visiting public from the exposure by the patients. Japanese radiation protection law regulates working environmental radiation exposure by regularly measuring and filing the environmental dose for years. This study was aimed at measuring working environmental radiation dose in the nuclear medicine department of an university hospital located in Daejeon, Korea. We measured the accumulation radiation dose in air at 8 locations in the nuclear medicine department by using the same method as in Japan with glass dosimeters. The highest dose rate, 0.23 mSv per month, was measured at the waiting room, and the second one is at reception desk. Even though the doses were lower than the Korean constraint dose rate (0.3 mSv/week) at the boundary of the radiation controlled area, it was over the dose limit of public (1 mSv/y) and environment (0.25 mSv/y). Conclusionally, it was found that the new or additional procedure was necessary to less the exposure dose to the receptionist and guardians by the environmental radiation dose in the nuclear medicine department.

Use of a microscope stage-mounted Nickel-63 microirradiator for real-time observation of the DNA double-strand break response

Eukaryotic cells begin to assemble discrete, nucleoplasmic repair foci within seconds after the onset of exposure to ionizing radiation. Real-time imaging of this assembly has the potential to further our understanding of the effects of medical and environmental radiation exposure. Here, we describe a microirradiation system for targeted delivery of ionizing radiation to individual cells without the need for specialized facilities. The system consists of a 25-micron diameter electroplated Nickel-63 electrode, enveloped in a glass capillary and mounted in a micromanipulator. Because of the low energy of the beta radiation and the minute total amount of isotope present on the tip, the device can be safely handled with minimum precautions. We demonstrate the use of this system for tracking assembly of individual repair foci in real time in live U2OS human osteosarcoma cells. Results indicate that there is a subset of foci that appear and disappear rapidly, before a plateau level is reached ∼30 min post-exposure. This subset of foci would not have been evident without real-time observation. The development of a microirradiation system that is compatible with a standard biomedical laboratory expands the potential for real-time investigation of the biological effects of ionizing radiation.

Lens autofluorescence is not increased at high altitude

To study the relation between ambient environmental ultraviolet radiation exposure and lens fluorescence. Non-invasive lens fluorometry measurements were compared in healthy Bolivian and Danish subjects. Background ultraviolet radiation was 4.5 times higher in Bolivia than in Denmark. No significant differences in lens fluorescence or transmittance were found between Bolivian and Danish volunteers. Age-corrected lens fluorescence and transmittance were comparable for healthy participants living at high altitude near the equator and healthy volunteers living at sea level at 55 degrees northern latitude. These results suggest that lens ageing, as assessed by lens autofluorometry, is independent of exposure to ultraviolet radiation.

Assessment of environmental radioactivity levels in Jimeta area of metropolitan Yola, Adamawa state

A radiological survey was carried out over Jimeta area of metropolitan Yola, Adamawa State, using a portable radiation alert monitor 4 of S. E. International, Inc. USA. The study showed that a mean whole body dose equivalent rate of 0.83 ± 0.11 mSv/y and mean absorbed dose rate of 1.19 ± 0.17 mGy/y resulted from total environmental radiation in Jimeta. Allowing for a cosmic radiation of 0.28 mGy/y the mean absorbed dose due to the environmental radioactivity is therefore 0.91 mGy/y. These values are lower than the 1 mSv/y recommended to the average individual member of the public by International Commission on Radiological Protection (ICRP). Hence residents of Jimeta are not unduly exposed to health risk due to environmental radiation exposure.

Radiation exposure from radioactive iodine 131I in and surrounding the patients' room

The purpose of this study is to measure the environmental radiation exposure in and surrounding the room of patients treated with (131)I. Absorbed dose rates were measured using thermoluminescence dosemeters, type TLD-200 (CaF(2):Dy), in a continuous monitoring programme. It is found that the estimated annual shallow and deep dose rates are 226 and 175 mGy at the patient bed; 94 and 72 mGy in the bathroom; and 12 and 10 mGy at the visitor chair, respectively. The annual absorbed dose in the corridor is almost at the background level. It is found that the annual doses at the patient bed and in bathroom were above the limit for radiation workers, whereas the dose rate at the visitor chair was within the accepted limit for radiation workers and above the limit for the public.

DNA Damage-related Gene Expression as Biomarkers to Assess Low Dose Radiation Exposure

According to the UNSCEAR, the natural rays from the Sun and the Earth transmit about 2,4 mSv to each individual every year. Human activities expose us to an additional radiation dose (1,2 mSv/year), especially the techniques used in non-invasive medical imaging (radiography, CT scanners). Ionizing radiation can induce a large spectrum of DNA lesions, but under optimal DNA repair conditions, the principal residual lesions of importance are misrepaired double-strand breaks / 1 /. Predictive markers of intrinsic radio sensitivity in healthy individuals are needed in monitoring their occupational or environmental radiation exposure and may predict a patient's response to radiotherapy. Radiation protection requires a thorough understanding of low dose ionizing radiation. Currently extrapolation from high doses is necessary to estimate the effects of low doses. Furthermore, it is critically important to have an appreciation of the variation in individual responses to radiation among the human population / 2 /. Appearance of mutations consist one of more prominent consequence of the radiation action. The aim of our study consisted in the restriction fragment's length polymorphism (RFLP) analysis of pERT87-8/Tag1 and 16intron/Tag1 loci with determining of presence or absence of restriction site in the group of radiologists and in control group. It was demonstrated that the pERT87-8/Tag1 allele frequency on «mutant» chromosome was 2,4 fold higher than the frequency of this allele on «normal» chromosome (45,1% in compare with 18,5%, X2=27,7, df=1, p<0.01). Therefore, in radiologists was revealed statistically significant difference of the frequency of polymorphic site pERT87-8/Tag1 compared to healthy donors. As for 16intron/Tag1 system it have been elucidated that the without restriction allele frequency site on «normal» chromosome was 2,0 fold higher than the frequency of this allele on «mutant» chromosome (71,5% in compare with 34,8%) χ2=78,3, df=1, p<0,01). In the conclusion it is necessary to mention that there are significant difference in the frequency of the polymorph sites pERT87-8/Tag1 and 16intron/Tag1 in the group of radiologists in compare with the control group. Reference 1. Karine Bishay et al. DNA damage-related RNA expression to assess individual sensitivity to ionizing radiation // Carcinogenesis, Vol. 22, No. 8, 1179-1183, 2001. 2. Robert C. Millikan et al. Polymorphisms in DNA Repair Genes, Medical Exposure to Ionizing Radiation, and Breast Cancer Risk // Cancer Epidemiology Biomarkers & Prevention Vol. 14, 2326-2334, October 2005.

Assessment of alpha activity of building materials commonly used in West Bengal, India

This paper, reports for the first time, an extensive study of alpha activity of all widely used building materials (plaster of Paris, stone chips, marble, white cement, mosaic stone, limestone, sand, granite, cement brick, asbestos, red brick, cement tile, ceramic tile and ceramics) in West Bengal, India. The alpha activities have been measured using Solid State Nuclear Track Detector (SSNTD), a very sensitive detector for alpha particles. The samples were collected from local markets of Kolkata. The measured average alpha activities ranged from 22.7 ± 2.5 to 590.6 ± 16.8 Bq kg −1. The alpha activity of ceramic tiles was highest and provides additional data to estimate the effect of environmental radiation exposure on human health.

Measurement of natural radioactivity in chemical fertilizer and agricultural soil: evidence of high alpha activity

People are exposed to ionizing radiation from the radionuclides that are present in different types of natural sources, of which phosphate fertilizer is one of the most important sources. Radionuclides in phosphate fertilizer belonging to 232Th and 238U series as well as radioisotope of potassium (40K) are the major contributors of outdoor terrestrial natural radiation. The study of alpha activity in fertilizers, which is the first ever in West Bengal, has been performed in order to determine the effect of the use of phosphate fertilizers on human health. The data have been compared with the alpha activity of different types of chemical fertilizers. The measurement of alpha activity in surface soil samples collected from the cultivated land was also performed. The sampling sites were randomly selected in the cultivated land in the Midnapore district, which is the largest district in West Bengal. The phosphate fertilizer is widely used for large agricultural production, mainly potatoes. The alpha activities have been measured using solid-state nuclear track detectors (SSNTD), a very sensitive detector for alpha particles. The results show that alpha activity of those fertilizer and soil samples varies from 141 Bq/kg to 2,589 Bq/kg and from 109 Bq/kg to 660 Bq/kg, respectively. These results were used to estimate environmental radiation exposure on human health contributed by the direct application of fertilizers.

Mortality among residents of Uravan, Colorado who lived near a uranium mill,1936–84

A cohort mortality study was conducted of all adult residents who ever lived inUravan, Colorado, a company town built around a uranium mill. Vital status wasdetermined through 2004 and standardised mortality analyses conducted for 1905 menand women alive after 1978 who lived for at least 6 months between 1936 and1984 in Uravan. Overall, mortality from all causes (standardised mortality ratio(SMR) 0.90) and all cancers (SMR 1.00) was less than or as expected based onUS mortality rates. Among the 459 residents who had worked in undergrounduranium mines, a significant increase in lung cancer was found (SMR 2.00; 95% CI1.39–2.78). No significant elevation in lung cancer was seen among the 767 femaleresidents of Uravan or the 622 uranium mill workers. No cause of death of a prioriinterest was significantly increased in any group, i.e. cancers of the kidney, liver,breast, lymphoma or leukaemia or non-malignant respiratory disease, renal diseaseor liver disease. This community cohort study revealed a significant excess oflung cancer among males who had been employed as underground miners. Weattribute this excess to the historically high levels of radon in uranium mines of theColorado Plateau, coupled with the heavy use of tobacco products. There wasno evidence that environmental radiation exposures above natural backgroundassociated with the uranium mill operations increased the risk of cancer. Although thepopulation studied was relatively small, the follow-up was long, extending up to65 years after first residence in Uravan, and nearly half of the study subjects haddied.

A comparative review of charged particle microbeam facilities

At the low doses (and low dose rates) relevant to environmental and occupational radiation exposure (0-50 mSv), which are of practical concern for radiation protection, very few cells in the human organism experience more than one traversal by densely ionising particles in their lifetime, the intervals between the tracks, if any, typically being months or years. The biological effects of exactly one particle are not well known and cannot be simulated in vitro by conventional broad-beam exposures, due to the random Poisson distribution of tracks. Charged particle microbeam facilities are a unique tool that allows targeting of single cells and analysis of the induced damage on a cell-by-cell basis. In the past few years, many charged particle microbeam facilities for radiobiology have come into operation or are under development worldwide. Different experimental designs have been adopted at various laboratories regarding the achievement of micrometre (or sub-micrometre) ion beam size, by mechanical collimation or focusing, particle detection, and cell recognition and positioning systems. The different approaches are reviewed and discussed in this paper.

Uses of Dosimetry in Radiation Epidemiology

Radiation epidemiology seeks to describe and quantify the risk of health effects, often cancer, in populations exposed to ionizing and non-ionizing radiation. To do so, it is important to estimate organ or tissue doses for large numbers of exposed individuals with a moderate to high degree of certainty. Unlike dosimetry for establishing compliance with regulations, which relies on doses estimated for representative, maximally exposed, or highest-risk persons, dosimetry for analytical epidemiological studies usually requires developing new dosimetric models or tailoring existing ones to reach a higher level of individualization. The majority of radiation epidemiological studies conducted to date have required the reconstruction of dose to individuals or study populations that were exposed many years ago. This presents a major challenge to researchers, because measurements often are not available or do not exist in forms that are directly usable for calculating radiation doses on an individual basis. The goal of this special issue of Radiation Research is to introduce readers to an array of dosimetric methods and applications that have been developed to reconstruct radiation exposures for epidemiological studies. We intend to fill a void in the technical literature by describing these methods in terms understandable to epidemiologists, dosimetrists and statisticians so that these research tools can be used by other members of the research community. This publication follows the 1995 National Academy of Sciences/National Research Council report entitled Radiation Dose Reconstruction for Epidemiologic Uses(1). That book summarized the views and expertise of a group of scientists who participated in a workshop on dose reconstruction for environmental radiation exposures. Since then, the methods for dose reconstruction have continued to advance, and the knowledge gained from epidemiological studies of populations exposed to radiation from many different sources has grown. It is therefore timely to publish a special issue of Radiation Research devoted to the methods used to estimate medical, occupational and environ