1. The Effects of Radiation on Living Things Standard Grade Physics Health Physics
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3. What types of radiation are harmful? Why is ionising radiation harmful? Radiation
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6. Short-term effects usually occur when there’s a large amount of exposure to radiation. Short-Term Effects of Radiation
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9. During the Second World War, two atomic bombs were dropped on Hiroshima and Nagasaki in Japan. Those people who survived the blast were exposed to a large dose of radiation. Such doses caused severe damage to cells all over the body, especially in the skin, blood, bone tissue and gut. Many of these people died within a few weeks. Those people who were exposed to a smaller dose recovered from such immediate effects. WW2 – Hiroshima and Nagasaki
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11. There was also a huge nuclear accident at the Chernobyl Nuclear Power station in the former USSR in 1986. Workers there were carrying out experiments on the reactor rods which caused fires to start. A number of firemen were exposed to very large amounts of radiation and 30 people died as a result. The damage to the power station was extensive but the radiation effects over a wide area were considerable. Chernobyl Nuclear Power Station
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13. Long-Term Effects of Radiation These effects take longer to become apparent and can be caused by much lower levels of radiation. Uranium miners tended to get lung cancer due to breathing in gases which emitted alpha particles. People who painted the dials of clocks with luminous paint developed one cancer from using their lips to make points on the brushes. One of the most important long-term effects of radiation is that of cancer in various parts of the body.
14. Exposure to ionising radiation does not necessarily cause cancer The mechanisms for cancer occurring are poorly understood at the moment. One theory is that the ionising radiation affects the DNA material within us – our genetic make-up. Our DNA contains genetic instructions which control the operation and reproduction of the cells. If ionisations caused by ionising radiations alter these instructions in the DNA, there is a chance that cancer will develop. Genetic damage can be caused to cells by radiation, including cells which are involved in reproduction.
15. Quality Factor Different types of radiation have different effects on living cells. Even though the same type of tissue may receive the same dose, the biological effects of different radiations will be different. To take this into account, a quality factor is assigned to all types of radiation. The quality factor, Q, allows the effects that different radiations have on living cells to be compared.
16. Quality Factor The quality factor for each type of radiation is shown below: From this it can be seen that alpha radiation is the most ionising radiation out of the three types. Radiation Quality Factor (Q) Alpha particles 20 Beta particles 1 Gamma rays 1
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18. Because 1 Sv is a very large dose of radiation which could only happen as a result of a very serious nuclear accident or explosion, doses are given in millisieverts (mSv) or microsieverts ( Sv). The DOSE EQUIVALENT is measured in sieverts (Sv).
19. Suppose that 100 people all receive a dose equivalent of 1 Sv spread over the whole body. It is estimated that, of the 100 people on average 4 of them would eventually die as a result of the radiation. But precisely who would die, or when they would die, or what illness they would die of, cannot be predicted.
21. Natural Sources of Radiation Source Annual Dose ( Sv) Radon and thoron gas from rocks and soil 800 Gamma rays from ground 400 Carbon and potassium in your body 370 Cosmic rays at ground level 300 Total = 1870
22. Man-Made Sources of Radiation Source Annual Dose ( Sv) Medical uses – x-rays, etc. 250 Chernobyl (first year) 50 Fall-out from weapons testing 10 Job (average) 5 Nuclear industry (e.g. waste) 2 Others (TV, aeroplane trips, etc.) 11 Total = 328
23. Death Risk - Cause Death Risk - Cause Death Risk – 40 Year Old All causes 1 per 500 Smoker – 10 per day 1 per 2000 Road accidents 1 per 5000 Home accidents 1 per 10 000 Work accidents 1 per 20 000 All radiations 1 per 27 500 Medical Radiations 1 per 240 000
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