What Does Radiation Do to Us?
Any radiation exposure can potentially have negative effects on health. This can be considered as the basic principle of radiation protection. It is therefore no surprise that damage due to ionising radiation was first observed very soon after the discove
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What Does Radiation Do to Us?
The technology used to detect if vehicles are carrying radioactive material is so sensitive it can tell if a person recently received radiation as part of a medical procedure. Timothy Murphy 1952–
Any radiation exposure can potentially have negative effects on health. This can be considered as the basic principle of radiation protection. It is therefore no surprise that damage due to ionising radiation was first observed very soon after the discovery of radioactivity by Becquerel. The biological effect of ionising radiation is a consequence of the energy transfer, by ionisation and excitation, to cells in the body. The biological effects of radiation absorption are shown in Figure 7.1 in detail. Figure 7.2 shows a very rough classification of different types of radiation damage. Usually they are divided into three different categories (early, delayed and genetic), as discussed in the next three subsections.
7.0.1 Early Effects This radiation damage occurs immediately after the irradiation, and only appears for high radiation doses. From a whole-body dose of 0.25 Sv upwards, it is possible to see the effects using a blood test (haemogram). For doses of around 1 Sv, clear symptoms of radiation sickness are to be expected. However, the recovery of the patients is nearly guaranteed if sufficient medical care is available. For a whole-body dose of 4 Sv, the chance of survival is 50 %. This dose is called the lethal dose. For a dose of 7 Sv, the death rate is nearly 100 % (see Figure 7.3). For high radiation doses, the symptoms of radiation sickness occur within a few hours of irradiation. The symptoms are headaches, nausea and vomiting. These symptoms normally disappear after some time. After a quiet period of several days almost without any symptoms, the second phase of the radiation sickness starts. The © Springer International Publishing Switzerland 2016 C. Grupen and M. Rodgers, Radioactivity and Radiation, DOI 10.1007/978-3-319-42330-2_7
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7 What Does Radiation Do to Us?
Fig. 7.1 Timings of the biological effects of absorbed radiation energy
symptoms are then fever, haemorrhage, vomiting of blood, bloody faeces and loss of hair. For the highest radiation doses, the quiet phase will be shorter or may even not occur. If the exposed person survives for eight weeks, there is good reason to expect a complete recovery from radiation sickness. However, in some cases death can occur after several months. Biological tissue has several different repair mechanisms, giving it some ability to rectify damage. Therefore, there is a threshold dose for early effects after irradiation. This means that below a certain dose, no lasting damage is observed. This threshold dose depends on how the dose was distributed in time, and which parts of the body are affected. The smallest value of the threshold is about 0.5 Sv (which is when the exposure all happened at once), and it is closer to 1 Sv if the dose is spread over a longer period. Radiation exposure from natural radiation is certainly far b
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