Biological effects of ionising radiation

Ionising nuclear radiation can remove electrons from molecules in living cells. This process, called ionisation, can damage the molecules and interfere with the normal functioning of a cell.

The damage may kill the cell. It may also alter the cell’s DNA, producing a mutation: a change in the genetic information carried by the DNA.

If a mutation disrupts the control of cell division, the affected cells may divide uncontrollably. This can lead to cancer. Not every mutation causes cancer.

The radiation dose received is a measure of the energy absorbed from radiation. As the dose increases, the risk of harm from cell damage also increases.

Safe handling of radioactive materials

Safe handling has two aims: to limit people’s exposure to ionising radiation and to prevent radioactive material from spreading. Exposure occurs when radiation reaches a person. Contamination occurs when radioactive material gets onto or into a person, or spreads into the surroundings.

Reducing exposure to radiation

Exposure can be reduced in three ways:

• Time: Spend as little time as necessary near a source. Less time near it means less exposure.
• Distance: Keep as far from the source as practicable. Tongs allow a source to be handled without bringing the hands close to it.
• Shielding: Place suitable material between the source and people to reduce the radiation reaching them. A lead container can provide shielding.

Containment and storage of radioactive sources

Radioactive sources should be transported in secure, suitably shielded containers. They should be taken out only when needed and returned to labelled, shielded storage when not in use. This limits unnecessary exposure and helps keep the source contained.

Containment and appropriate protective equipment also help prevent radioactive material from reaching people or spreading into the surroundings. Shielding reduces radiation exposure, whereas containment prevents the material itself from spreading.