Radiation is a general term refering to any sort of energy that can travel through space either as a wave or a particle.
In considering related health risks, radiation may be classed as:
- non-ionising radiation (low energy)
- ionising radiation (high energy)
You will usually only be exposed to man-made ionising radiation during certain medical tests, but the levels are so low that the chances of problems developing are small.
The types and sources of radiation are described in more detail below.
Examples of non-ionising radiation include:
- ultraviolet radiation
- visible light
- infrared radiation
- radio and radar waves
- wireless internet connections (wifi)
- mobile phone signals
Overall, there is little evidence to suggest most types of non-ionising radiation are harmful at levels you are normally exposed to, but some forms of non-ionising radiation are potentially dangerous.
The main proven danger of non-ionising radiation is damage to the skin caused by ultraviolet (UV) light. UV light primarily comes from the sun, but is also produced by sunbeds and sunlamps.
Low levels of exposure to UV light are actually beneficial to health as sunlight helps our bodies produce vitamin D, which is important as it helps keeps bones strong and healthy.
However, high levels of exposure to UV light can be harmful as it can cause sunburn, as well as increasing your risk of developing melanoma and non-melanoma skin cancer.
Some people have also argued that telecommunications devices which use non-ionising radiation, such as mobile phones or wifi, could be potentially dangerous.
So far, a number of studies, both in the UK and internationally, have not identified any health risks associated with these devices.
A research programme known as the Mobile Telecommunications and Health Research (MTHR) Programme is ongoing in the UK. Their most recent report in 2007 concluded there is no evidence that short-term use of mobile phones increases the risk of cancer or affects the normal functioning of the brain.
This has been supported by further studies in the last two years, which also show no link between mobile phones and problems such as cancer.
However, it is widely accepted that, as mobile phones have only been widely used for about 10 years, it may be too early to detect possible long-term risks or problems that may be associated with them.
Read more about mobile phone safety
Radiation in medical tests and treatments
Ionising radiation is a more powerful form of radiation than non-ionising radiation and is therefore more likely to cause damage to cells. Exposure to ionising radiation can increase the risk of cancer and high doses can cause serious damage, including radiation burns.
One of the most common sources of exposure to man-made ionising radiation is during medical tests or treatments.
For example, tests such as X-rays and CT scans use small amounts of ionising radiation.
Ionising radiation in the form of gamma rays is also common in what is known as nuclear medicine. This is a branch of medicine where radioactive substances can be used to help diagnose, and sometimes treat, a condition – for example a mild radioactive substance is injected into the blood stream so it shows up better on an imaging scan.
In terms of treatments, radiotherapy is a common cancer treatment that uses ionising radiation to kill cancerous cells.
However, while it may sound dangerous, the radiation used in medicine is closely controlled and the risk of any problems resulting from exposure to radiation is very small.
Measuring radiation exposure
The low levels of radiation you are exposed to during medical tests can be measured in units called millisieverts (mSv).
Some examples of different levels of radiation exposure are listed below.
- A single chest X-ray (0.02 mSv) – This is equivalent to the amount of radiation you would be exposed to during a return flight from London to Spain (the higher up in the atmosphere you are, the less protection you have against cosmic rays).
- A year’s worth of medical tests (0.4 mSv) – This is the average dose for each person in the UK each year as a result of medical tests, such as X-rays.
- Natural radiation (2.2 mSv) – The average annual dose that a person in the UK receives from natural sources (read about background radiation below).
- A mammogram (2 to 5 mSv) – The amount of radiation that a woman receives after having a mammogram (a type of X-ray used during breast cancer screening). The benefit of detecting breast cancer at an early stage is likely to outweigh the risk of any problems from the radiation exposure.
- A computerised tomography (CT) scan of the chest, abdomen and pelvis (10 mSv) – The amount of radiation a person receives from a CT scan (a machine that uses a series of X-rays to create an image of the inside of the body).
- Working with radiation (20 mSv) – The UK legal limit, as set by the Ionising Radiations Regulations (1999), that a classified person who works with radiation may be exposed to in any given year. However, most workers receive considerably less than this.
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There is conflicting evidence about the risks faced by people who regularly work with radiation. These people include nuclear power workers and medical professionals who use radioactive technology, such as X-rays and CT scanners.
Some studies have shown that people working with radiation have a higher risk of problems such as cancer, heart disease and stroke, while other studies have actually indicated that there is a lower risk of these problems.
Improvements in safety standards mean it is now estimated that only 6% of radiation workers are likely to be exposed to high levels of ionising radiation (100mSv or more) during their career, which should reduce the chances of problems developing.
There is also currently no evidence that children of people who work with radiation have an increased risk of developing serious health conditions such as birth defects or leukaemia.