Internal radiation exposure from neutron-induced radioisotopes environmentally activated following atomic bombing or nuclear accidents should be considered for a complete picture of pathologic effects on survivors. Inhaled hot particles expose neighboring tissues to locally ultra-high doses of β-rays and can cause pathologic damage. 55MnO2 powder was activated by a nuclear reactor to make 56MnO2 which emits β-rays. Internal exposures were compared with external γ-rays. Male Wistar rats were administered activated powder by inhalation. Lung samples were observed by histological staining at six hours, three days, 14 days, two months, six months and eight months after the exposure. Synchrotron radiation—X-ray fluorescence—X-ray absorption near-edge structure (SR–XRF–XANES) was utilized for the chemical analysis of the activated 56Mn embedded in lung tissues. 56Mn beta energy spectrum around the particles was calculated to assess the local dose rate and accumulated dose. Hot particles located in the bronchiole and in damaged alveolar tissue were identified as accumulations of Mn and iron. Histological changes showed evidence of emphysema, hemorrhage and severe inflammation from six hours through eight months. Apoptosis was observed in the bronchiole epithelium. Our study shows early event damage from the locally ultra-high internal dose leads to pathogenesis. The trigger of emphysema and hemorrhage was likely early event damage to blood vessels integral to alveolar walls.

Optimisation of the parameters for recording the electron paramagnetic resonance (EPR) spectra of dental enamel for absorbed dose reconstruction was performed for an EMX (Bruker) spectrometer supplied with a high-sensitivity microwave cavity. Dose determination was performed using a previously developed automatic spectra processing procedure, which uses the non-linear fit of a model spectrum. The experimental error was estimated as the standard deviation of the results from the nominal doses for the set of spectra recorded for 10 samples prepared from teeth of different persons and irradiated in the dose range 0-500 mGy. The microwave power and magnetic field modulation amplitude corresponding to the minimum of dependencies of the error on these parameters were adopted as the optimal ones. For the sets of spectra recorded at optimal parameters for sample masses 100, 50 and 30 mg, the errors of dose determination were obtained as 18, 27 and 37 mGy respectively.

Aims and Scope Eurasian Journal of Medicine (Eurasian J Med) is an international, scientific, open access periodical published by independent, unbiased, and triple-blinded peer-review principles. The journal is the official publication of Atatürk University School of Medicine and published triannually in February, June, and October. The publication language of the journal is English. The aim of the Eurasian Journal of Medicine is to publish original research papers of the highest scientific and clinical value in all medical fields. The Eurasian J Med also includes reviews, editorial short notes and letters to the editor that either as a comment related to recently published articles in our journal or as a case report. The target audience of the journal includes researchers, physicians and healthcare professionals who are interested or working in in all medical disciplines.

Background Ionizing radiation is a known cause of female breast cancer, but there have been few studies of the risk after prolonged radiation exposure at low dose rates. Methods This population-based case-control study estimated breast cancer risk after ∼25 years’ exposure to radiation from the Chernobyl accident. Cases (n = 468) were women ≤55 years old when first diagnosed with invasive breast cancer during October 2008 through  February 2013, who lived in Bryansk Oblast, Russia at the time of the accident and their diagnoses. Controls, individually matched to cases on birth year, administrative district of residence and urban vs non-urban settlement during the accident, were women without breast cancer who lived in Bryansk Oblast at the time of the accident and on their cases’ diagnosis dates (n = 468). Subjects were interviewed regarding residence, dietary and food source histories to support individualized estimation of their radiation doses to the breast, which ranged from 0.04 − 41 centigray (cGy) (mean 1.3 cGy). Results In multivariable analyses, the odds ratio for breast cancer risk was 3.0 [95% confidence interval (CI): 1.3, 7.0] and 2.7 (95% CI: 1.0, 7.3) in the seventh and eighth dose octiles, respectively, relative to the lowest octile. Analyses of dose effect modification suggested that radiation-related risk may have been higher in women who were younger at the time of the accident and/or at the time of diagnosis. Conclusions This study suggests that prolonged exposure to ionizing radiation at low dose rates can increase risk of breast cancer.

To understand the radiation effects of the atomic bombing of Hiroshima and Nagasaki among the survivors, radiation from neutron-induced radioisotopes in soil should be considered in addition to the initial radiation directly received from the bombs. 56Mn, which emits both β particles and γ-rays, is one of the dominant radioisotopes created in soil by neutrons from the bomb. Thus we investigated the biological effects of internal exposure to 56MnO2 particle in the lung of male Wistar rats comparing to the effects of external 60Co-γ irradiation. Absorbed doses of internal irradiation of lungs were between 25 and 65 mGy in 56MnO2-exposed animals, while the whole body doses were between 41 and 100 mGy. Animals were examined on days 3 and 61 after the exposure. There were no remarkable pathological changes related to 56MnO2 particle exposure. However, mRNA and protein expressions of aquaporin 5 increased significantly in the lung tissue on day 3 postexposure in 56MnO2 groups (by 1.6 and 2.9 times, respectively, in the highest dose group). Smad7 mRNA expression was also significantly elevated by 30% in the highest dose group of 56MnO2. Our data demonstrated that internal exposure to 56MnO2 induced significant biological responses including gene expression changes in the lungs, while external 60Co-γ irradiation of 2 Gy did not show any changes.

To investigate the biological effects of internal exposure of radioactive 56MnO2 powder, the major radioisotope dust in the soil after atomic bomb explosions, on male reproductive function, the gene expression of the testes and the prostate was examined. Ten-week-old male Wistar rats were exposed to three doses of radioactive 56MnO2 powder (41–100 mGy in whole body doses), stable MnO2 powder, or external 60Co γ-rays (2 Gy). Animals were necropsied on Days 3 and 61 postexposure. The mRNA expressions of testicular marker protein genes and prostatic secretory protein genes were quantified by Q-RT-PCR. On Day 3 postexposure, the testicular gene expressions of steroidogenesis-related enzymes, Cyp17a1 and Hsd3b1, decreased in 56MnO2-exposed groups. Germ cell-specific Spag4 and Zpbp mRNA levels were also reduced. On postexposure Day 61, the Cyp11a1 gene expression became significantly reduced in the testes in the group exposed to the highest dose of 56MnO2, while another steroidogenesis-related StAR gene mRNA level reduced in the 60Co γ-rays group. There were no differences in Spag4 and Zpbp mRNA levels among groups on Day 61. No histopathological changes were observed in the testes in any group following exposure. Expression in the prostatic protein genes, including CRP1, KS3, and PSP94, significantly decreased in 56MnO2-exposed groups as well as in the 60Co γ-rays group on Day 61 postexposure. These data suggest that the internal exposure to 56MnO2 powder, at doses of less than 100 mGy, affected the gene expressions in the testis and the prostate, while 2 Gy of external γ-irradiation was less effective.

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At the detonation of the atomic bombing in Hiroshima and Nagasaki, a significant amount of radionuclides was produced by the neutron induced activation. The residual radiation from the explosion is crucial to the health risk of the people who entered these cities after the bombing and might have inhaled these radioactive materials. Because 56 Mn is one of the major radionuclides produced in soil and have not been studied until now, we had conducted a series of experiments using rats to investigate the biological impacts of exposure of 56 MnO 2 particles. In these experiments, the rats’ spontaneous locomotor activity was also assessed to examine the possible effects of 56 Mn on their behavior. However, the locomotor activity data obtained from an individual experiment failed to identify radiation effects due to the large variation among animals and the small sample size. In the present study, all available data from our previous studies on 56 MnO 2 exposure (0.02–0.15 Gy of whole-body doses) as well as 60 Co-γ exposure (at 2–5 Gy of whole-body doses) were pooled. Our statistical method, which takes into account individual differences and daily fluctuations, successfully identified a decrease in locomotor activity caused by 56 MnO 2 exposure, where the changes were gradual and reached the maximum reduction around 2 weeks after exposure. In contrast, exposure to 60 Co-γ rays produced the highest decline of activity within one day. These results suggest that internal exposure to 56 Mn at whole-body doses of even less than 0.15 Gy may have a long-lasting impact on locomotor activity.