radiation biology

Study of how living things are affected by radioactive (ionizing) emissions (see radioactivity) and by electromagnetic (nonionizing) radiation (electromagnetic waves). Both are potentially harmful and can cause mutations as well as leukaemia and other cancers; even low levels of radioactivity are very dangerous. Both, however, are used therapeutically, for example to treat cancer, when the radiation dose is very carefully controlled (radiotherapy or X-ray therapy).

Radioactive emissions are more harmful. Exposure to high levels produces radiation burns and radiation sickness, plus genetic damage (resulting in birth defects) and cancers in the longer term. Exposure to low-level ionizing radiation can also cause genetic damage and cancers, particularly leukaemia.

Electromagnetic radiation is usually harmful only if exposure is to high-energy emissions, for example close to powerful radio transmitters or near radar-wave sources. Such exposure can cause organ damage, cataracts, loss of hearing, leukaemia and other cancers, or premature ageing. It may also affect the nervous system and brain, distorting their electrical nerve signals and leading to depression, disorientiation, headaches, and other symptoms. Individual sensitivity varies and some people are affected by electrical equipment, such as televisions, computers, and refrigerators.

Background radiation is the natural radiation produced by cosmic rays and radioactive rocks such as granite, and this must be taken into account when calculating the effects of nuclear accidents or contamination from power stations.