[B._Beckhoff,_et_al.]_Handbook_of_Practical_X-Ray_(b-ok.org).pdf

Dose limits for exposed workers as stated in the eu

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Dose limits for exposed workers as stated in the EU Directive 96/29 [5] annual limit for exposed body dose organ workers effective dose whole body 20 mSv a organ dose lens of the eye 150 mSv hands, forearms, feet 500 mSv and ankles local skin dose 1 cm 2 of the skin 500 mSv a The EU Directive says that the limit shall be 100 mSv over five consecutive years, subject to a maximum effective dose of 50 mSv in any single year. The Member States may fix an annual amount. to damage to the germ cells in the reproductive organs. Radiation causes ionisation of the cell constituents (mainly water) causing chemical reactions. By these, the complex molecules which form chromosomes can become broken. These effects can cause early death of the cell, prevent or delay cell division, or pass on a permanent modification to the daughter cells. An acute exposure is one in which a large dose is received over a few hours or less. Radiation sickness, which occurs a few hours after an acute exposure, is due to damage to the cells lining the intestine. An acute whole body dose above 1 Sv will produce this effect. At these dose levels the effective dose is no longer an appropriate measurand, therefore, the absorbed dose is used instead. A dose of about 3–4 Gy is lethal for 50% of an exposed population within a few months. For whole body doses from 4 up to 10 Gy, death is due to secondary infections due to depletion of the white blood cells which normally protect against infection. Above 10 Gy gross damage occurs in the lining of the intestine and is followed by severe bacterial invasion. Whole body doses at these levels are extremely unlikely in case of X-ray fluorescence analytical instrumentation, but low doses may still cause harmful effects in the long term. Cancer may result from damage to the control system of a single cell, causing it to divide rapidly, the defect being transmitted to the daughter cells. There is a long and variable latent period of 5 to 30 years or more between exposure and appearance of the cancer. The fact that radiation- induced cancers are not normally distinguishable from others leads to much uncertainty as to the risk at low levels of exposure. It is possible that there is a threshold below which cancer induced by radiation does not occur, but it is normally assumed that there is a linear relationship between dose and risk and that any dose, no matter how small, carries some risk. According to ICRP [3], the combined risk of cancer induction and hereditary (genetic) effects is between 5% and 7% per Sv; which means that of 100 persons exposed to 1 Sv between 5 and 7 persons get the mentioned hazard.
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8 Appendix 841 Local Exposure In case of an accident, using X-ray fluorescence analytical instrumentation, local exposures are much more likely than whole body exposures. Fortunately, the effects of local exposure are much less than those of whole body exposures.
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