China
Africa
Explore chapters and articles related to this topic
Theoretical Background to Radiation Protection
Published in W. P. M. Mayles, A. E. Nahum, J.-C. Rosenwald, Handbook of Radiotherapy Physics, 2021
Mike Rosenbloom, W. P. M. Mayles
Because of the low incidence of radiation-induced cancer compared with the natural incidence of the disease, there is little direct evidence of the magnitude of the risk for doses below 200 mSv. The possibility of a threshold below which radiation is not harmful is a subject of much controversy. Studies of large cohorts, such as the study of British radiologists, have failed to show any increased risk associated with the low doses they received (Berrington et al. 2001). Some have argued that very small doses of radiation may even be beneficial (so-called radiation hormesis) (Cameron and Moulder 1998; Siegel et al. 2017a), bearing in mind the existence of natural background radiation. BRER (2006), ICRP (1990, 2007a) and the radiation protection community have, however, taken the view that in the absence of clear evidence to the contrary, a linear no-threshold model should be assumed. An excellent review of these issues is given by Johansson (2003). There is also a view that the effect of radiation at low doses is underestimated by the linear model (Hall et al. 2004), although the latest evidence from the LSS (Grant et al. 2017) does not support this. The majority view of the Committee Examining Radiation Risks of Internal Emitters (CERRIE 2004) is that the linear no-threshold model is the most appropriate.
Biological Effects and Medical Treatment
Published in Alan Perkins, Life and Death Rays, 2021
A brief history of radiation exposure and poisoning would not be complete without some more detailed explanation of the human biological effects of radiation. The first point to appreciate is the difference between radiation exposure and radiation dose. Exposure arises from the amount of something in the surroundings to which the person may become ‘exposed’, whereas the dose is the total amount of the thing taken in or absorbed by the body. The next point to consider is the toxic effect of the absorbed dose. The ingestion of common salt (sodium chloride) is a good example of chemical dose-related toxicity. Salt is essential for human health in small amounts, but large doses may be harmful, particularly to cardiovascular function. This comes back to the previously described scientific view that a medicine is a small amount of a poison. There is even a school of thought that this may be true for radiation. Radiation hormesis is the hypothesis that low doses of ionising radiation around or slightly above background levels are beneficial to health and stimulate cellular repair mechanisms that help to protect against disease. Although there have been scientific studies to test this hypothesis, this concept is not supported by most international scientific authorities and government bodies.
Hormesis
Published in T. D. Luckey, Radiation Hormesis, 2020
Hormology is the study of excitation. Hormesis is the stimulation of any system by small amounts of any agent. Large amounts of the same agent slow or stop the system, whether it is a physical, chemical, or biologic system. Radiation hormesis in biology is the stimulation of physiologic functions evoked by exposure to low doses of ionizing radiation.
Radiobiology in my life – Irma Mosse
Published in International Journal of Radiation Biology, 2022
Low radiation doses – are they harmful or beneficial? There is no direct evidence of negative influence of low radiation doses on heredity. All investigations related to the human health in populations from the regions with a high radiation background have revealed no genetic effects and no harmful consequences for health and lifespan. The ‘hormesis’ phenomenon proves positive effects of a low radiation dose (Otake et al. 1990; Cuttler and Pollycove 2009). The main proof of stimulating effects of low radiation doses is radioadaptive response in which a low priming dose protects cells or organism against a high second dose. This phenomenon is well-known and nobody has doubts in its existence (Calabrese 2008; Pollycove and Feinendegen 2001). Life is already accustomed to a low dose or dose rate of radiation within a range of naturally occurring radiation. Radiation hormesis is explained, pointing out that beneficial effects are expected following a low dose or dose rate, because protective responses against stresses are stimulated (Cuttler and Pollycove 2009).
Dose-dependent long-term effects of a single radiation event on behaviour and glial cells
Published in International Journal of Radiation Biology, 2021
Marie-Claire Ung, Lillian Garrett, Claudia Dalke, Valentin Leitner, Daniel Dragosa, Daniela Hladik, Frauke Neff, Florian Wagner, Horst Zitzelsberger, Gregor Miller, Martin Hrabĕ de Angelis, Ute Rößler, Daniela Vogt Weisenhorn, Wolfgang Wurst, Jochen Graw, Sabine M. Hölter
In sum, our findings indicate that not only during embryonic and post-natal development, as well known from the literature, but also early in adult life a single radiation event has long-lasting effects on behaviour and glia that, depending on the dose, can be deleterious or beneficial. The beneficial low dose-induced behaviour and microglial changes at older age imply a protective effect. This is consistent with radiation hormesis theory that low dose radiation can have stimulating effects on living organisms, particularly on the immune system (Luckey 1999; Cui et al. 2017; Lumniczky et al. 2017; Dubbelaar et al. 2018). We can now also hypothesize that the neuroprotective-like low dose radiation-induced microglia phenotype may fortify the brain against certain ageing effects. This is given that the ageing-associated converse, where microglia err towards a pro-inflammatory-like phenotype, is associated with increased vulnerability to neurodegenerative disease (Perry and Holmes 2014; Ojo et al. 2015). We also identified a possible adaptive response of Ercc2S737P het mice to age-related decline. In future experiments, it would be interesting to investigate further the molecular neurobiological mechanisms both of successful ageing and of the time course of changes in hippocampal cell populations and microenvironment after exposure to ionizing radiation in the adult brain. In addition, there remains a need to analyse comprehensively cell populations altered in the extra-hippocampal brain regions such as neocortex and thalamus that may also explain the behavioural changes described here.
Low-dose ionizing radiation attenuates mast cell migration through suppression of monocyte chemoattractant protein-1 (MCP-1) expression by Nr4a2
Published in International Journal of Radiation Biology, 2019
Chin-Hee Song, Hae Mi Joo, So Hyun Han, Jeong-In Kim, Seon Young Nam, Ji Young Kim
In contrast to high-dose radiation, low-dose radiation exerts beneficial effects, also known as ‘radiation hormesis’, that promote growth and development of normal cells, enhance immune functions, and inhibit cancer progression (Luckey 2006). Recent studies have demonstrated that low-dose ionizing radiation can potentially be used for the clinical treatment of rheumatoid arthritis, asthma, allergies, and other immune system diseases (Nakatsukasa et al. 2008; Kim et al. 2015). We previously reported that low-dose ionizing radiation prevents the release of inflammatory immune mediators, such as histamine, β-hexosaminidase, and cytokines, from activated RBL-2H3 mast cells (Joo et al. 2012) and attenuates allergic responses by suppressing immune cell infiltration into inflammatory sites (Joo et al. 2015). Chemotaxis of mast cells into inflammatory sites and their subsequent release of mediators promote the inflammatory response. In the current study, we sought to identify the regulatory mechanisms by which low-dose ionizing radiation attenuates mast cell migration and thereby inhibiting the inflammatory response.