Effects Of Low-dose Radiation Exposure Research Articles

Factors Influencing Effects of Low-dose Radiation Exposure.

It is now well accepted that the mechanisms induced by low-dose exposures to ionizing radiation (LDR) are different from those occurring after high-dose exposures. However, the downstream effects of these mechanisms are unclear as are the quantitative relationships between exposure, effect, harm, and risk. In this paper, we will discuss the mechanisms known to be important with an overall emphasis on how so-called "non-targeted effects" (NTE) communicate and coordinate responses to LDR. Targeted deposition of ionizing radiation energy in cells causing DNA damage is still regarded as the dominant trigger leading to all downstream events whether targeted or non-targeted. We regard this as an over-simplification dating back to formal target theory. It ignores that last 100 y of biological research into stress responses and signaling mechanisms in organisms exposed to toxic substances, including ionizing radiation. We will provide evidence for situations where energy deposition in cellular targets alone cannot be plausible as a mechanism for LDR effects. An example is where the energy deposition takes place in an organism not receiving the radiation dose. We will also discuss how effects after LDR depend more on dose rate and radiation quality rather than actual dose, which appears rather irrelevant. Finally, we will use recent evidence from studies of cataract and melanoma induction to suggest that after LDR, post-translational effects, such as protein misfolding or defects in energy metabolism or mitochondrial function, may dominate the etiology and progression of the disease. A focus on such novel pathways may open the way to successful prophylaxis and development of new biomarkers for better risk assessment after low dose exposures.

Radioactive decay, health and social capital: Lessons from the Chernobyl experiment

We exploit the random variation in health patterns across European regions that resulted from the Chernobyl nuclear disaster to provide new quasi-experimental evidence on the causal effect of health patterns on social capital. Our instrumental variable estimations show that the radioactive fallout is positively associated with an increase in hospital discharges after treatment for neoplasms almost thirty years later, the magnitude of the effect being in line with other studies investigating the health effects of low-dose radiation exposure. An increased incidence of neoplasms in the local area of residence induced by the radioactive fallout, and the resulting perception of higher risks of contracting potentially deadly diseases among the healthy population, generates a sizeable impoverishment of social capital and a reduction in social interactions, altruism and happiness. Our findings suggest that health care and prevention policies may have additional returns in terms of a significant increase in communities’ social capital.

Detection of biological responses to low-dose radiation in humans

It has been considered difficult to detect the biological effects of low-dose radiation exposure below approximately 100 mSv in humans. Serum proteomic analysis and oxidative modification profiling were conducted with blood samples collected from residents of a newly discovered high-level natural background radiation area (annual effective dose approximately 50 mSv y−1) and normal-level area (1.22 mSv y−1) in Mamuju, Indonesia, where many people have been living for generations. Dose-dependent oxidative modifications in amino acid sequences of human serum albumin, especially the 162nd and 356th tyrosine residues and 111th and 470th methionine residues, were found. None of these findings have been reported in humans exposed to chronic low-dose radiation. It can be used as a biomarker not only for the assessment of the presence or absence of radiation exposure but also for dose prediction in living organisms for chronic radiation. These results suggest that traces of radiation exposure are recorded in serum albumin and that there is a possibility of a new methodology that can evaluate biological responses below 100 mSv.

A Risk Comparison between Lifestyle, Socioeconomic Status, and Radiation: A Cohort Study of Cancer Mortality among Japanese Nuclear Workers (J-EPISODE).

The health effects of low-dose radiation exposure have been a source of controversy. One possible reason is that epidemiological studies that compare radiation risk with other factors, such as lifestyle or socioeconomic status, have been limited. The aim of this study is to conduct a comparison of the cancer risk of mortality between radiation, lifestyle habits (such as smoking), and socioeconomic status (such as years of education) among Japanese nuclear workers. We assembled a cohort of 41,742 male nuclear workers in Japan who answered a lifestyle questionnaire survey conducted during 2003-2004. To exclude systematic errors caused by missing values, we used multiple imputation and Poisson regression to estimate relative risks and confidence intervals for lifestyle habits, socioeconomic status, and radiation. The total person-y from 2005 to 2010 were 215,000. The mean age and cumulative dose were 54.9 y and 24.8 mSv (10-y lagged dose), respectively. Significantly high relative risks were determined for smoking, alcohol consumption, frequency of medical examination, breakfast intake, sleep, and body mass index. Further, significantly high relative risks of radiation were shown for lung cancer and smoking-related cancers. Since the simultaneous inclusion of radiation and non-radiation variables in the model for relative risk (RR) calculation means that the calculated radiation RR is the result of adjustment by other variables, the risk of cancer from low-dose radiation, if any, is less than smoking and probably less than other lifestyle factors.

Nutrient Imbalance of the Host Plant for Larvae of the Pale Grass Blue Butterfly May Mediate the Field Effect of Low-Dose Radiation Exposure in Fukushima: Dose-Dependent Changes in the Sodium Content.

Simple SummaryThe pale grass blue butterfly has been used to monitor the biological impacts of the Fukushima nuclear accident because this butterfly is sensitive to low-dose radioactive pollution in the field. However, the butterfly has been shown to be highly tolerant to radioactive cesium (137Cs), the major radionuclide in Fukushima, in an artificial diet in laboratory experiments. This field-laboratory paradox may be explained by the field-effect hypothesis; the host plant may change its nutrient contents in response to radiation stress. Leaves from Tohoku (mostly polluted areas including Fukushima) showed significantly lower sodium contents than those from Niigata. In Tohoku samples, an increase in the radioactivity concentration of cesium (137Cs) in leaves or in the ground radiation dose was accompanied by a decrease in the sodium content. The sodium content appeared to be related to other nutrient factors. Thus, the sodium imbalance of the plant may be caused by radiation stress, and this imbalance may be one of the reasons that this monophagous butterfly showed high mortality and morphological abnormalities in the field shortly after the accident in Fukushima.The pale grass blue butterfly Zizeeria maha is sensitive to low-dose radioactive pollution from the Fukushima nuclear accident in the field but is also highly tolerant to radioactive cesium (137Cs) in an artificial diet in laboratory experiments. To resolve this field-laboratory paradox, we hypothesize that the butterfly shows vulnerability in the field through biochemical changes in the larval host plant, the creeping wood sorrel Oxalis corniculata, in response to radiation stress. To test this field-effect hypothesis, we examined nutrient contents in the host plant leaves from Tohoku (mostly polluted areas including Fukushima), Niigata, and Kyushu, Japan. Leaves from Tohoku showed significantly lower sodium and lipid contents than those from Niigata. In the Tohoku samples, the sodium content (but not the lipid content) was significantly negatively correlated with the radioactivity concentration of cesium (137Cs) in leaves and with the ground radiation dose. The sodium content was also correlated with other nutrient factors. These results suggest that the sodium imbalance of the plant may be caused by radiation stress and that this nutrient imbalance may be one of the reasons that this monophagous butterfly showed high mortality and morphological abnormalities in the field shortly after the accident in Fukushima.

Associated factors related to participation in general health checkup and survey of the effect of low-dose radiation exposure on health of residents of Fukushima Prefecture after the Fukushima Daiichi nuclear power plant accident.

The Fukushima Daiichi nuclear power plant accident caused radioactive contamination of the surrounding area. In addition to annual health checkups, a survey of the effects of low-dose radiation exposure on health among Fukushima Prefecture residents after the accident has been conducted. Despite health literacy (HL) being recognized as essential to health, its association with participation in these checkups and the survey remains unknown. We aimed to describe the HL status of the Fukushima Prefecture residents and to verify the hypothesis that HL is associated with participation in both checkup and survey. In a cross-sectional study, a questionnaire was sent to 2000 randomly sampled Fukushima Prefecture residents; data from 770 individuals were analyzed. Communicative and critical HL were measured using a 5-point scale. Factors associated with participation were examined using logistic regression. The survey's valid response rate was 38.5%. The average HL score was 3.11±0.81. HL was not associated with checkup or survey participation. Checkup participation was negatively associated with radiation anxiety (odds ratio 0.93, 95% confidence interval 0.86-0.99, p=0.03). The HL of Fukushima Prefecture residents after the accident was relatively lower than that of the Japanese general population, which may be attributed to difference in educational background. The complexities involved in understanding the effects of radiation on the health of residents could explain why no association between HL and participation in a health checkup and survey was observed. Future studies with a longitudinal design should clarify causality between anxiety and checkup participation.

Absorbed radiation doses in the thyroid as estimated by UNSCEAR and subsequent risk of childhood thyroid cancer following the Great East Japan Earthquake.

The identification of thyroid cancers among children after the Chernobyl nuclear power plant accident propelled concerns regarding long-term radiation effects on thyroid cancer in children affected by the Fukushima Daiichi nuclear power plant accident in Fukushima, Japan. Herein we consider the potential association between absorbed dose in the thyroid and the risk of developing thyroid cancer as detected by ultrasonography on 300 473 children and adolescents aged 0–18 years in Fukushima. The absorbed dose mentioned in the present study indicates the sum of that from external exposure and that from internally deposited radionuclides. We grouped participants according to estimated absorbed doses in each of 59 municipalities in Fukushima Prefecture, based on The United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) 2013 report. The 59 municipalities were assigned to quartiles by dose. We limited our analyses to participants aged ≥6 years because only one case of thyroid cancer was observed in participants aged ≤5 years; 164 299 participants were included in the final analysis. Compared with the lowest dose quartile, the age- and sex-adjusted rate ratios (95% confidence intervals) for the low-middle, high-middle and highest quartiles were 2.00 (0.84–4.80), 1.34 (0.50–3.59) and 1.42 (0.55–3.67) for the 6–14-year-old groups and 1.99 (0.70–5.70), 0.54 (0.13–2.31) and 0.51 (0.12–2.15) for the >15-year-old group, respectively. No dose-dependent pattern emerged from the geographical distribution of absorbed doses by municipality, as estimated by UNSCEAR, and the detection of thyroid cancer among participants within 4–6 years after the accident. Ongoing surveillance might further clarify the effects of low-dose radiation exposure on thyroid cancer in Fukushima.

Assessment of Ionizing Radiation Effects on the Hematological Parameters of Radiation-Exposed Workers

Long-term exposure to low doses of ionizing radiation may adversely affect human cells and tissues of hospital radiation workers, especially peripheral blood cell count . Blood cell count analysis is a useful screening test in a routine medical checkup. A high or low blood cells count even in a healthy-looking subject lead s to the suspicion of disease and it should prompt further investigation s . This study was aimed to assess the effects of ionizing radiation on the hematological parameters of radiation workers at several governmental hospitals in Indonesia and correlation between years of employment and equivalent dose on one hand and the hematological parameters on the other . It included 74 medical radiation workers occupationally exposed to low doses of ionizing radiation at the Unit of Radiology and Radiotherapy and 83 controls. Fourteen hematological parameters were measured by ABX Micros 60 Hematology analyzer and the correlation between years of employment and equivalent dose as well as hematological parameters on radiation-exposed workers were tested by linear regression analysis test. Our study reported that red blood cell and monocyte co unt s were significantly higher in radiation-exposed workers compared to controls, whereas white blood cells, hematocrit, mean corpuscular volume , and lymphocytes values were significantly lower in radiation-exposed workers. A significant correlation was observed between equivalent dose and red blood cells (RBCs) parameter (P=0.001) with a decline in RBC level of 0.541×10 6 /µL per 1 mSv increase of radiation dose. The present study recommends that further studies should use a larg er sample size and include various independent variables (genetic polymorphism, chromosome aberration, micronucleus frequency) to study the long-term effects of low-dose radiation exposure on radiation-exposed workers.

The REPAIR Project: Examining the Biological Impacts of Sub-Background Radiation Exposure within SNOLAB, a Deep Underground Laboratory.

Considerable attention has been given to understanding the biological effects of low-dose ionizing radiation exposure at levels slightly above background. However, relatively few studies have been performed to examine the inverse, where natural background radiation is removed. The limited available data suggest that organisms exposed to sub-background radiation environments undergo reduced growth and an impaired capacity to repair genetic damage. Shielding from background radiation is inherently difficult due to high-energy cosmic radiation. SNOLAB, located in Sudbury, Ontario, Canada, is a unique facility for examining the effects of sub-background radiation exposure. Originally constructed for astroparticle physics research, the laboratory is located within an active nickel mine at a depth of over 2,000 m. The rock overburden provides shielding equivalent to 6,000 m of water, thereby almost completely eliminating cosmic radiation. Additional features of the facility help to reduce radiological contamination from the surrounding rock. We are currently establishing a biological research program within SNOLAB: Researching the Effects of the Presence and Absence of Ionizing Radiation (REPAIR project). We hypothesize that natural background radiation is essential for life and maintains genomic stability, and that prolonged exposure to sub-background radiation environments will be detrimental to biological systems. Using a combination of whole organism and cell culture model systems, the effects of exposure to a sub-background environment will be examined on growth and development, as well as markers of genomic damage, DNA repair capacity and oxidative stress. The results of this research will provide further insight into the biological effects of low-dose radiation exposure as well as elucidate some of the processes that may drive evolution and selection in living systems. This Radiation Research focus issue contains reviews and original articles, which relate to the presence or absence of low-dose ionizing radiation exposure.

Cancer Incidence after In Utero Exposure to Ionizing Radiation in Techa River Residents.

Health effects of in utero exposure to ionizing radiation, especially among adults, are still unclear. The aim of this study was to analyze cancer risk in a cohort of subjects exposed in utero due to releases of nuclear waste into the Techa River in the Southern Urals, taking into account additional postnatal exposure. Analysis for solid cancer was based on 242 cases among 10,482 cohort members, accumulating 381,948 person-years at risk, with follow-up from 1956-2009, while analysis for hematological malignancies was based on 26 cases among 11,070 persons, with 423,502 person-years at risk, with follow-up from 1953-2009. Mean doses accumulated in soft tissues and in red bone marrow during the prenatal period were 4 mGy and 30 mGy, respectively. Additional respective mean postnatal doses received by cohort members were 11 and 84 mGy. Poisson regression analysis was used to estimate the excess relative risk (ERR) of cancer incidence related to in utero and postnatal doses. No association was observed for in utero exposure with solid cancer risk [ERR per 10 mGy: -0.007; 95% confidence interval (CI): <-0.107; 0.148] or with hematological malignancy risk (ERR/10 mGy: -0.011; 95% CI: <-0.015; 0.099). However, ERR of solid cancer increased significantly with increasing postnatal dose (ERR/10 mGy: 0.11; 95% CI: 0.04; 0.22). The very wide confidence intervals in these ERR results are similar to those of studies performed on the LSS cohort and the offspring of the Mayak Female Worker Cohort, as well as case-control studies of effects after in utero medical exposure. There were limitations of this study, with decreased statistical power, due to the low prenatal doses received by most of the cohort members, the small number of cancer cases and the absence of cohort members over the age of 59 years (living cohort members had reached 49-59 years of age). Further aging of the cohort and extension of the follow-up period will enhance the statistical power of this study in the future. There is a shortage of cohort studies reporting on the effects of prenatal radiation exposure, as well as information on chronic exposure during the prenatal period. Therefore, further research of this unique cohort will be a useful addition to the published literature on this subject, and a valuable means of elucidating the long-term effects of low-dose radiation exposure in the fetus.

Scientific feuds, polemics, and ad hominem arguments in basic and special-interest genetics.

Scientific disputes are commonly presented and settled in journal publications. Most are resolved by a weighing of evidence and new findings. In some cases the arguments are personal and in the form of ad hominem attacks on the personality or integrity of an author of a journal article. Many famous scientists (e.g., Galileo, Newton, and Hooke) used ad hominem arguments in responding to their critics. William Bateson, W.F.R. Weldon, William Castle, and H.J. Muller used ad hominem arguments in their publications until the end of World War I, when editorial policy of journals changed. Motivating some of the attacks are philosophic differences (such as holistic or reductionist approaches to science), ideological differences (such as Marxist or Capitalist outlooks), politics (such as Cold War depictions by East and West on fallout from nuclear testing), or conflicts of interest (which can be professional or financial such as the debates over nontraditional and orthodox medicine or over tobacco smoking and health). Most of the time, the disputes are motivated by honest disagreements over the interpretation of the data. A recent surge (2009-2016) of ad hominem attacks by Edward Calabrese has appeared disparaging H. J. Muller, E. B. Lewis, other twentieth-century contributors to radiation genetics, and the National Academy of Sciences. They address the mutational effects of low-dose radiation exposure. Calabrese's attacks have led to responses by geneticists in the field of mutagenesis, by agencies criticized by Calabrese, and by students and colleagues of those who have been accused of deception by Calabrese. This article reviews some of the history of ad hominem arguments in science and the background to the attacks by Calabrese. I argue that Calabrese's characterization of Muller and his supporters is unjust, misleading, and hurtful. I also propose some methods for dealing with or preventing ad hominem attacks in professional journals.

DNA damage-associated biomarkers in studying individual sensitivity to low-dose radiation from cardiovascular imaging.

The use of diagnostic imaging and image-guided interventions using low-dose ionizing radiation has increased dramatically in recent years. This is explained by dramatic advances in imaging technology which provide invaluable diagnostic information for clinical decision-making.1 Although the benefits of appropriate use of advanced imaging technology outweigh the risks, the medical use of X-ray-based imaging techniques has become a leading source of man-made radiation exposure to the general population. According to a recent report by the National Council on Radiation Protection and Measurements, the total radiation exposure from medical imaging has increased six-fold from the early 1980s to the present, and currently almost 40% of medical radiation exposure (excluding radiotherapy) comes from cardiovascular imaging and image-guided interventions.2,3 This has prompted renewed interest in the potential long-term risks of low-dose radiation exposure for patients, physicians, and technical staff members.4,5 Clinical decision-making inherently requires balancing the potential benefits of e.g. a cardiac-imaging procedure and intervention with the projected risks, including those from radiation exposure. Although risk estimates for low-dose radiation exposures and international guidelines exist,6,7 these have been developed predominantly for the purpose of radiation protection and the development of occupational dose limits for radiation exposed workers (such as some physicians). Risk estimates for medical low-dose radiation exposure are associated with substantial uncertainties—to some extent this is due to the fact that our understanding of the biological effects of low-dose radiation exposure in humans is incomplete.6,8 Radiation dose from medical imaging, commonly referred to as effective dose, is expressed in units of millisieverts, which is the weighted average of the absorbed dose in mGy multiplied …

A report from the 2013 international symposium: the evaluation of the effects of low-dose radiation exposure in the life span study of atomic bomb survivors and other similar studies.

The RERF International Low-Dose Symposium was held on 5-6 December 2013 at the RERF campus in Hiroshima, Japan, to discuss the issues facing the Life Span Study (LSS) and other low-dose studies. Topics included the current status of low-dose risk detection, strategies for low-dose epidemiological and statistical research, methods to improve communication between epidemiologists and biologists, and the current status of radiological studies and tools. Key points made by the participants included the necessity of pooling materials over multiple studies to gain greater insight where data from single studies are insufficient; generating models that reflect epidemiological, statistical, and biological principles simultaneously; understanding confounders and effect modifiers in the current data; and taking into consideration less studied factors such as the impact of dose rate. It is the hope of all participants that this symposium be used as a trigger for further studies, especially those using pooled data, in order to reach a greater understanding of the health effects of low-dose radiation.

James V. Neel and Yuri E. Dubrova: Cold War debates and the genetic effects of low-dose radiation.

This article traces disagreements about the genetic effects of low-dose radiation exposure as waged by James Neel (1915-2000), a central figure in radiation studies of Japanese populations after World War II, and Yuri Dubrova (1955-), who analyzed the 1986 Chernobyl nuclear power plant accident. In a 1996 article in Nature, Dubrova reported a statistically significant increase in the minisatellite (junk) DNA mutation rate in the children of parents who received a high dose of radiation from the Chernobyl accident, contradicting studies that found no significant inherited genetic effects among offspring of Japanese A-bomb survivors. Neel's subsequent defense of his large-scale longitudinal studies of the genetic effects of ionizing radiation consolidated current scientific understandings of low-dose ionizing radiation. The article seeks to explain how the Hiroshima/Nagasaki data remain hegemonic in radiation studies, contextualizing the debate with attention to the perceived inferiority of Soviet genetic science during the Cold War.

An analysis of the argument over the health effects of low-dose radiation exposure caused by the accident at the Fukushima Daiichi APP in Japan

Since the accident at the Fukushima Daiichi Atomic Power Plant last March, there has been a huge controversy over the potential health effects of low-dose radiation exposure. This paper critically examines the argument between mainstream experts and nonmainstreamers, which is revealed as an interdisciplinary argument caused by the differences in the specialties to which the experts belong. The concepts of confounding control and statistical significance, which are epidemiologically powerful tools that can disprove the argument that harm was caused by other causes, appeared to be less effective for denying the existence of a hazard entirely. The concept of risk is the most significant cause of confusion related to low-dose exposure because the epidemiologists assume that risk is the incidence rate of diseases, but biologists believe that risk includes DNA damage that may cause cancer in the future. This paper also reveals that public debate is useful to make collective choices and decisions rationally when inferential questions become the subjects of dispute.

Chemoprevention by N-acetylcysteine of low-dose CT-induced murine lung tumorigenesis.

Data from the National Lung Screening Trial suggested that annual computed tomography (CT) screening of at-risk patients decreases lung cancer mortality by 20%. We assessed the effects of low-dose CT radiation in mice exposed to 4-(methylnitrosoamino)-1-(3-pyridyl)-1-butanone (NNK) to mimic the effects of annual CT screening in heavy smokers and ex-smokers. A/J mice were treated at 8 weeks with NNK followed 1 week later by 4 weekly doses of 0, 10, 30 or 50 mGy of whole-body CT and euthanized 8 months later. Irradiated mice exhibited significant 1.8- to 2-fold increases in tumor multiplicity in males (16.1 ± 0.8 versus 9.1 ± 1.5 tumors per mouse; P < 0.0001) and females (21.6 ± 0.8 versus 10.5 ± 1.4 tumors per mouse; P < 0.0001), respectively, compared with unirradiated mice with no dose effect observed; female mice exhibited higher sensitivity to radiation exposure than did males (P < 0.0001). Similar results were obtained when tumor area was determined. To assess if the deleterious effects of radiation could be prevented by antioxidants, female mice were fed a diet containing 0.7% N-acetylcysteine (NAC) starting 3 days prior to the first CT exposure and continuing for a total of 5 weeks. NAC prevented CT induced increases in tumor multiplicity (10.5 ± 1.2 versus 20.7 ± 1.5 tumors per mouse; P < 0.0001) back to levels seen in NNK/unirradiated mice (10.5 ± 1.2). Our data suggest that exposure of sensitive populations to CT radiation increases the risk of tumorigenesis, and that antioxidants may prevent the long-term carcinogenic effects of low-dose radiation exposure. This would allow annual screening with CT while preventing the potential long-term toxicity of radiation exposure.

A review of some epidemiological studies on cancer risk from low-dose radiation or other carcinogenic agents

It is extremely difficult to assess cancer risks accurately due to health effects of low-dose radiation exposure or other carcinogens based on epidemiological studies. For the detection of minute increases of the risk at low-level exposure, most of epidemiological studies lack statistical power, and they involve various complicated confounding factors. This paper reports on a literature survey of epidemiological studies published since 2000 on cancer risks associated with low-dose radiation and other carcinogens to gather major epidemiological data. Integrated risk indices were derived from those data by using, where possible, statistical models. Regarding risk assessment of low-dose radiation exposure, it is important to lower the degree of uncertainty arising from risk estimation. Risk assessment of low-dose radiation exposure could be scientific evidence when uncertainty is considered in comparing carcinogenic risks of radiation with those of other carcinogens.

The health effects of low-dose radiation exposure

Low dose radiation has been defined as doses in the range under 100 mSv of low linear energy transfer (low-LET) radiation. There are two sources of ionizing radiation: natural and artificial radiation. Medical radiation exposure is the most common artificial radiation exposure. The frequency and volume of medical radiation exposure has markedly increased because of recent developments in medical technology. Radiation protection is now a concern due to the increasing use of computed tomography (CT) scans and diagnostic X-rays. This article introduced several models and hypotheses regarding the possible carcinogenic risks associated with low-LET radiation. Although opinions vary on the health effects of low level radiation exposure, current studies of medical radiation rely on exposure information collected prospectively, including cohort studies such as atomic bomb survivor studies. Although there are differences in perspective, the majority of studies have supported ‘linear-no-threshold model without threshold’ between low-LET radiation and the incidence of cancer risk. There is a need for further studies on medical radiation exposure including CT and positron emission tomography in order to understand the health effects of low-LET radiation, including the cancer incidence.

Low-dose environmental radiation, DNA damage, and cancer: The possible contribution of psychological factors

Radiation causes DNA damage, increases risk of cancer, and is associated with psychological stress responses. This article proposes an evidence-based integrative model in which psychological factors could interact with radiation by either augmenting or moderating the adverse effects of radiation on DNA integrity and eventual tumorigenesis. Based on a review of the literature, we demonstrate the following: (1) the effects of low-dose radiation exposures on DNA integrity and on tumorigenesis; (2) the effects of low-dose radiation exposure on psychological distress; (3) the relationship between psychological factors and DNA damage; and (4) the possibility that psychological stress augments and that psychological resource variables moderate radiation-induced DNA damage and risk of cancer. The additional contribution of psychological processes to radiation–DNA damage–cancer relationships needs further study, and if verified, has clinical implications.

Genetic polymorphisms in XRCC1, OGG1, APE1 and XRCC3 DNA repair genes, ionizing radiation exposure and chromosomal DNA damage in interventional cardiologists

Interventional cardiologists working in high-volume cardiac catheterization laboratory are exposed to significant occupational radiation risks. Common single-nucleotide polymorphisms (SNPs) in DNA repair genes are thought to modify the effects of low-dose radiation exposure on DNA damage, the main initiating event in the development of cancer and hereditary disease. The aim of this study was to determine the relationship between XRCC1 ( Arg194Trp and Arg399Gln), OGG1 ( Ser326Cys), APE1 ( Asp148Glu) and XRCC3 ( Thr241Met) SNPs and chromosomal DNA damage. We enrolled 77 subjects: 40 interventional cardiologists (27 male, 41.3 ± 9.4 years and 13 female, 37.8 ± 8.4 years) and 37 clinical cardiologists (26 male, 39.4 ± 9.5 years and 11 female, 35.0 ± 9.8 years) without radiation exposure as the control group. Micronucleus (MN) assay was performed as biomarker of chromosomal DNA damage and an early predictor of cancer. MN frequency was significantly higher in interventional cardiologists than in clinical physicians (19.7 ± 7.8‰ vs. 13.5 ± 6.3‰, p = 0.0003). Within the exposed group, individuals carrying a XRCC3 Met241 allele had higher frequency than homozygous XRCC3 Thr241 (21.2 ± 7.8‰ vs. 16.6 ± 7.1‰, p = 0.03). Individuals with two or more risk alleles showed a higher MN frequency when compared to subjects with one or no risk allele (18.4 ± 6.6‰ vs. 14.4 ± 6.1‰, p = 0.02). An interactive effect was found between smoking, exposure >10 years and the presence of the two or more risk alleles on the MN frequency ( F = 6.3, p = 0.02). XRCC3 241Met alleles, particularly in combination with multiple risk alleles of DNA repair genes, contribute to chromosomal DNA damage levels in interventional cardiologists.