Radiation and Cancer

Radiation is the way in which energy is propagated through a material medium or a vacuum in the form of particles or electromagnetic waves.

We differentiate between types of radiation according to how much energy they transmit, the main distinction being between ionising and non-ionising radiation. Ionising radiation carries more energy than non-ionising radiation, enough to cause the atoms in the matter with which it interacts to gain or lose electrons. By contrast, non-ionising radiation does not transmit sufficient energy to trigger this kind of change (ionization), but it can cause other chemical reactions, induce electrical currents and cause heating (for example, in the case of microwaves).

In our daily life, we are surrounded by ionising and non-ionising radiation from both natural and artificial (man-made) sources. Natural sources of ionising radiation include minerals rich in uranium and other radioactive elements that are present in the earth, radioactive elements that accumulate in certain plants, and cosmic rays from outer space. Examples of natural sources of non-ionising radiation are the sun (ultraviolet radiation, visible light, infrared light, microwaves, and radio waves) and the Earth's magnetic field.

Owing to their diverse properties, both types of radiation are used in many different technologies, and these create artificial sources of radiation: ionising radiation is used in applications ranging from nuclear power plants to radiation therapy and diagnostic tests;  non-ionising radiation is used in all electrical and electronic devices as well as in telecommunications and anti-theft technologies. Nevertheless, the levels of radiation we are exposed to in daily life as a result of using these technologies are very low, and each country has strict regulations to ensure that this exposure does not exceed levels considered safe.

We know that the exposure of a human being to certain doses of ionising radiation can cause irreparable damage to the structure of their DNA, that is, to the genes that control their cell function, and that such damage triggers a series of changes that may lead to cancer, as explained by Miren Taberna in this post. To date no similar effects on DNA have been demonstrated on exposure to non-ionising types of radiation. So, do we have to avoid exposure to ionising radiation?

Apart from people who work directly with radiation sources or who live in homes where there is a high level of radon, we are not normally exposed to ionising radiation. Some medical procedures use ionising radiation to diagnose or treat disease. For example radiograph imaging (X-rays), tomography (CT) and radiotherapy, but in these cases the benefits derived from the diagnostic imaging or the cure obtained by radiation in the case of tumour therapy far outweigh the risks incurred.

Although we are surrounded by many new sources of non-ionising radiation, including mobile phones, Wi-Fi Internet and microwave ovens, the doses we are exposed to are usually very low. These low levels of exposure to non-ionising radiation have not, to date, been shown to have any health effects: however, a lack of scientific evidence does not necessarily mean that no such effects exist, and scientists are continuing to investigate potential associations between exposure to non-ionising radiation and health effects. Although it is very unlikely that any adverse health effects are associated with the use of mobile phones, which use non-ionising radiation to communicate with antennas, you can take some simple precautions to reduce exposure until scientific studies have produced more results. For example, you can reduce your exposure by sending text messages instead of talking on the phone, by using a hands-free or speaker system, and by spending less time talking on the phone or making fewer calls. In an upcoming post, we will provide more details about recommendations on ways to reduce exposure to non-ionising radiation and evaluate their effectiveness.