Abstract
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.
Highlights
Radiation from neutron-induced radioisotopes in soil, dust and other materials should be considered to fully understand the radiation effects on the survivors of the Hiroshima and Nagasaki atomic bombings as well as those affected by nuclear power plant accidents and other nuclear disasters involving the scattering of hot particles [1], in addition to the initial radiation directly received from the bombs or other sources
The delayed effect of acute external radiation exposure was noted in a study by MacVittie et al [13]
The delayed effect external radiation exposure noted in a study and by MacVittie et al
Summary
Radiation from neutron-induced radioisotopes in soil, dust and other materials should be considered to fully understand the radiation effects on the survivors of the Hiroshima and Nagasaki atomic bombings as well as those affected by nuclear power plant accidents and other nuclear disasters involving the scattering of hot particles [1], in addition to the initial radiation directly received from the bombs or other sources This may be more important for evaluating the radiation risks to the people who moved to these cities soon after the detonations or other nuclear disasters and probably inhaled activated radioactive “dust”. Understanding the possibility of potential late effects occurring after a succession of cell turnover with the early stage internal β-ray exposure by 56 Mn with its short physical half-life, leads to a more complete picture of the pathologic effects of internal radiation
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