Biological effects of ionising radiation

It is assumed that within the range of exposure conditions usually encountered in radiation work, the risks of cancer and hereditary damage increase in direct proportion to the radiation dose. It is also assumed that there is no exposure level that is entirely without risk. Thus, for example, the mortality risk factor for all cancers from uniform radiation of the whole body is now estimated to be 1 in 25 per sievert (see below for definition) for a working population, aged 20 to 64 years, averaged over both sexes. In scientific notation, this is given as 4 X 10 per sievert. Effects of radiation, primarily cancer induction, for which there is probably no threshold and the risk is proportional to dose are known as stochastic, meaning of a random or statistical nature.  

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National Research Council, Committee on the Biological Effects of Ionising Radiations (1988) Health risks of radon and other internally deposited alpha emitters (BEIR IV). National Academy Press. Washington, DC. 

Blake, C. C. F. and Phillips, D. C. (1962) in Biological Effects of Ionising Radiation at the Molecular Level, IAEA Symposium, Vienna, and discussed in Blundell and Johnson (1976), p. 253. 

Biological Effects of Ionising Radiation, (BEIR) VI Report The Health Effects of Exposure to Indoor Radon, 1998, US Environmental Protection Agency, Washington DC, USA. 

It is clear that exposure of biological material to ionising radiation leads to a loss of function due to the modification of critical structures. Results of former space experiments suggest that the biological effect of space radiation could be enhanced under microgravity. 

The Effects on Population of Exposure to Low Levels of Ionising Radiation. Report of the Advisory Committee on the Biological Effects of Ionizing Radiations, Division of Medical Sciences, National Research Council. National Academy of Scienees, Washington, D.C., 1972. 

United Nations Scientific Committee on Effects of Atomic Radiations (1982) Ionising radiation sources and biological effects. New York, United Nations. 

UNSCEAR, Ionising radiation Sources and biological effects. United Nations Scientific Committee on the Effects of Atomic Radiation (1993). 

Space environment afreets almost all biological processes, in particular germination and flowering. Embryo lethality and lethal mutation frequency were observed in Arabidopsis thaliana seeds and in other organisms such as Escherichia coli and Bacillus suhtilif while very little is known about the effects of ionising and non-ionising radiation on photosynthetic apparatus. 

The radiation emitted during radioactive decay can cause the material through which it passes to become ionised and it is therefore called ionising radiation. X-rays are another type of ionising radiation. Ionisation can result in chemical changes which can lead to alterations in living cells and eventually, perhaps, to manifest biological effects. 

The individual types of ionising radiation resulting from nuclear processes have different biological effects. Therefore, in addition to the exposure dose (given in Gy), the so-called equivalent dose, absorbed by a given mass of biological tissue, was introduced. The equivalent dose (H) for tissue T and radiation type R is calculated by the formula = Q.D r, where Q is a radiation (radiobiological)... 

Radiation effects A vast material has been collected, about the formation of free radicals by ionising radiation and by photolysis in chemical and biochemical systems. The treatise [20] dealing with studies of primary radiation effects and damage mechanisms in molecules of biological interest is also a valuable source of information of ENDOR spectroscopy in solids. Specialised treatises of radiation effects in sohds involve studies of inorganic [21] and organic systems [22], radiation biophysics [20], radical ionic systems [23], radicals on surfaces [24], and radicals in sohds [25]. 

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