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Cancer and Leukaemia
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Ionising radiation can induce solid cancer, leukaemia and lymphoma. The
current knowledge about these effects is mainly based on
epidemiological studies among the survivors of the atomic bombing of
Hiroshima and Nagasaki, but studies on other radiation exposed
population enlarge the body of evidence. The cancer risk from radiation
depends mainly on the dose received, the type of radiation, the exposed
organ, and the age at exposure (full text in German).
by the United Nations Scientific Committee on Atomic Radiation (UNSCEAR). The last report on cancer risk was published in 2000, the next is to appear in 2008.
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Hereditary radiation effects
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 Exposure of the germ cells (gonads) can cause mutations in the genetic material which may result in heritable disease in the offspring of the exposed persons. Heritable diseases are expressed in children and further generations as malformations, metabolic malfuncions, immune deficiencies etc. Radiation induced heritable diseases can not be distinguished from spontaneous or chemically induced heritable diseases (full text in German only).
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Radiation exposure during pregnancy
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If a pregnant woman is exposed to ionizing radiation, there is a risk of radiation-induced malformations and developmental disorders for the unborn (termed as deterministic or non-stochastic effects, which have dose thresholds below which the effect does not occur). There is also an increased risk of cancer or leukaemia for prenatally exposed children (termed as stochastic effects).
In order to protect the unborn, every woman of childbearing age has to be asked, before the use of ionizing radiation in medical diagnosis or treatment, whether a pregnancy exists or could exist (in line with the German X-ray Ordinance / Radiation Protection Ordinance). If pregnancy is confirmed or cannot be excluded, there is urgent need for a careful risk-benefit evaluation which refers to the medical benefit of the mother of having the medical application of radiation and the radiogenic risk to the unborn. If possible, the examination should be delayed until the end of pregnancy or the possibility of alternative methods (with less or no dose, such as ultrasound or magnetic resonance imaging) should be considered.
According to current scientific knowledge, there is no risk of deterministic damage below a whole-body dose for the unborn of 50 mSv. With a single “standard” X-ray or nuclear medicine examination, the dose of 50 mSv for the unborn is not exceeded (full text in German only).
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Deterministic radiation effects
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Acute radiation injuries occur shortly after high radiation exposures, typically exceeding 500 Millisievert (mSv). These exposures lead to massive cell killing and subsequently to a loss of function of the affected organs or tissues. Usually, deterministic effects are acute effects. No such effects are observed below a dose of about 500 mSv. Above this dose-threshold the severity of the injury increases with dose and the damage appears earlier. Still, there are some late deterministic effects like lung fibrosis (full text in German only).
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Epidemiology
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Epidemiology is a methodology to investigate the distribution and determinants of health effects in populations. Several types of epidemiological studies can be distinguished. Cross-sectional and ecological studies provide valuable tools for generating hypotheses. However, they are limited in their explanatory power due to major methodological limitations. Cohort studies and case-control-studies are quite complex to perform but are of high significance for risk estimation, if bias and confounding can be limited. In contrast to animal experiments and cellular studies, epidemiological studies allow a direct quantification of the radiation-induced risk in humans.
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Risk Estimation and Risk Assessment
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The scientific basis for risk estimation and assessment is reviewed. The most important study of radiation-induced leukaemia and cancer is the Life Span Study (LSS) among the Japanese atomic bomb survivors. However, the data need to be extrapolated from high dose-rates to low dose-rates, from the limited observation time to life-time and from the Japanese population to other populations in the world. UNSCEAR considers the lifetime risk for leukaemia and solid cancer to be about twelve percent per Sievert for a population of all age groups (full text in German only).
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Dose Limits in Radiation Protection
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The annual dose limit for the general public is recommended by the ICRP to be 1 mSv per calendar year (without radon). For occupationally exposed persons, the limit of the effective dose is 20 mSv per year. For work places or conditions where a worker is exposed in an inhomogeneous radiation field, there are additional annual dose limits for organs such as eye lens and lung (150 mSv), skin and extremities (500 mSv), gonads and uterus (50 mSv) as well as thyroid gland (300 mSv). For people aged below 18 years the occupational exposure shall not exceed the effective dose of 1 mSv per year. To women who are not pregnant the uterus dose may not exceed 2 mSv per month. As soon as a pregnant woman informs the employer of her pregnancy, the dose to the unborn child shall not exceed 1 mSv during the remainder of pregnancy. In addition to these dose limits established by the European Guideline 96/29/EURATOM, Germany has introduced an occupational life-time dose limit of 400 mSv. Below the dose limits, the principle of optimisation requires that any radiation exposure is to be kept as low as possible by taking social and economic circumstances into account (full text in German).
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Individual Radiation Sensitivity
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 The term radiation sensitivity refers to biological reactions that render cells, tissues or organisms which are hypersensitive to the effects of ionizing radiation. Radiation sensitivity can be related to genetic and/or environmental factors and their interaction. Human beings bearing a radiation hypersensitive genotype can react with severe acute health effects such as skin damage or with retarded effects, such as an increased incidence of secondary cancer. At present, it seems unlikely that current estimates of radiation cancer risk in the population will be distorted by the small fraction of highly radiation sensitive individuals. However, radiation sensitivity has to be considered in individual risk assessment in medical and occupational settings (full text in German only).
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Consequences of Radiological Accidents
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The International Atomic Energy Agency's (IAEA) criteria for health consequences of radiation accidents are summarized in "Planning the medical response to radiological accidents", Vienna, IAEA, 1998, (Safety reports series, ISSN 0020-6450: no. 4), ISBN 92-0-102598-X (full text in German only).
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Health Effects by radon in homes
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 The adverse health effects of exposure to radon are caused primarily by damage due to alpha-particles. The main health hazard from radon exposure is an increased risk of lung cancer. Epidemiological studies showed that the exposure-response relation seems to be linear without evidence of a threshold. It is estimated that about five per cent of the lung cancer deaths per year are attributable to radon in homes in Germany (full text in German).
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Polonium-210: Gesundheitliche Bewertung
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In der Natur entsteht Polonium-210 durch den radioaktiven Zerfall von Uran-238. Es ist ein radioaktives Metall, das sich in chemischen Reaktionen ähnlich wie Wismut verhält. Die technische Herstellung von Polonium erfolgt im Kernreaktor durch Neutronenbeschuss von Wismut. Polonium kommt in geringsten Mengen (etwa 60 Becquerel) auch von Natur aus im menschlichen Körper vor.
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Plutonium
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The physical and chemical properties of plutonium are described. Plutonium is not only a chemical poison but also an emitter of alpha radiation. Health effects of external exposure can be neglected. Internal exposure can result in severe medical and biological effects. The inhalation of plutonium is accompanied by a higher lung, bone and liver cancer and leukaemia risk. There are only a few epidemiological studies available on plutonium exposed persons. The most important is the one conducted in Southern Urals, Russian Federation. Currently, risk estimates rely to a large extent on animal data (full text in Germn only).
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Uranium
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The physical and chemical properties of uranium are described. In principle, there are two health effects of uranium to be considered: health effects due to the metal properties of uranium (chemotoxic effects) and health effects due to radiation properties of uranium (radiotoxic effects). These health effects are described and evaluated in detail.
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Hormesis
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Hormesis is described as biopositive reaction of biological systems. The mechanism behind the hormetic effect is controversely discussed. There is no general mechanism known for the different hormetic effects, such as adaptive response. In view of the limited scientific knowledge up to now, hormesis is not considered for risk assessment (full text in German only).
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