Radiation exposure somatic effects

If a person is exposed to a large amount of radiation (i.e., large radiation dose) delivered to the entire body, cells in tissues can be destroyed in large numbers. Because tissues have important functions, the destruction of significant numbers of cells can lead to impairment in one or more of these functions. The biological effects that arise when large numbers of cells are destroyed by radiation are called acute somatic effects if they occur in a relatively short period of time (e.g., within a few weeks) after brief exposure. Acute somatic effects are a subset of what is now formally called early and continuing deterministic effects (once called nonstochastic effects). 

Deterministic effects are those that increase in severity as the radiation dose increases and for which a threshold is presumed to exist. Besides acute somatic effects, deterministic effects also include radiation effects (other than cancer and genetic effects) that continue to occur after an extended period (e.g., years) of chronic exposure. Such chronic exposures can arise from long-lived radionuclides (e.g., isotopes of plutonium and cesium) ingested via contaminated food or inhaled via contaminated air... 

The ICRP and the IAEA regularly issue recommendations for proper handling of radiation sources. The purposes of the recommended system of dose limitations are to ensure that no exposure is unjustified in relation to its benefits, that all necessary exposure is kept as iow as is reasonably achievable (the ALARA principle), and that the doses received do not exceed the specified limits. The ICRP stresses the values given in Table 18.11 they apply to the sum of the relevant doses from external exposure in die specified period and the SO-year committed dose (for children 70 years see also next ) in the same period. These values must be respected. They are intended to limit somatic effects in individuals, hereditary effects in the immediate offspring of irradiated individuals, and hereditary and somatic effects in the population as a whole. 

It is the philosophy of the International Commission on Radiological Protection (53) and of most scientists in this field, that the cautious assumption should be made that any exposure to radiation may carry some risk for the development of somatic effects, including leukemia and other malignancies, and of hereditary effects. The Commission and others recognize that this is a conservative assumption and that some effects may exhibit a minimum or threshold dose but most often, the simple pessimistic assumption is made that the chance of delayed radiation injury of this kind is directly proportional to the total dose accumulated by the organ in question (the whole body is included as a special case within this term). 

Sometimes irradiation will not kill the affected cells, but may only alter them. A viable but modified somatic cell may still retain its reproductive capacity and may give rise to a clone. If the clone is not eliminated by the body s defence mechanisms, after a prolonged and variable period of delay termed the latent period, it may result in the development of malignant conditions, usually termed cancers, which are the principal late somatic effects of exposure to radiation. In contrast to deterministic effects, it is assumed that there is no threshold of dose below which stochastic effects (e.g., cancer) cannot occur. These effects do not occur in every exposed individual the probability that an individual or one of his or her descendants may develop one of these effects increases with the dose received. Thus, even if the dose is very small, the person still has a chance, albeit a very small one, of incurring such an effect. 

In setting radiation limits, it is customary to assume that, for exposure of the whole body to radiation, the effect produced is proportional to the absorbed dose. Since this assumption ignores the possibility of damaged tissue repairing itself during long-term exposure to low radiation doses, it is believed to represent a conservative approach to the estimation of possible damage. Somatic effects where the probability of injury (e.g., the initiation of cancer) is proportional to the dose are known as stochastic effects. In contrast to these, an effect such as cataract of the eye is nonstochastic in this case, a threshold dose exists such that no cataract will be induced if the absorbed dose is below this amount. 

Ionizing radiation Exposure, genetic and somatic effect Nuclear reactor, accelerator, cyclotron, research laboratories. X-ray laboratories, radioisotope laboratories NRC 10 CFR 19, 20, 34, OSHA 29 CFR 1910.96, state laws... 

Human exposures to RF radiation arise from military use, industrial use, broadcasting, and cellular phone use. These exposures have been linked to increased numbers of spontaneous abortion, neurological effects, altered red and white blood cell counts, increased somatic mutation rates in lymphocytes, cardiovascular effects, increased cancer risk, and increased childhood cancers/28 311 Other studies.however, have refuted these findings) 27,32 As stated in the introduction, only a relatively few studies addressed the combined effects of toxic chemical and RF exposure. A thorough search of the literature shows that such studies have not been refuted. The following are illustrative examples of these mixture studies. 

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