Dangers of Radiation (Cambridge (CIE) O Level Physics): Revision Note

Dangers of Radioactivity

• Ionising radiation can damage human cells and tissues at high doses:

• This could be in terms of:

  1. Cell death

  2. Tissue damage

  3. Mutations

  4. Cancer

• As a result, its use needs to be kept to a minimum

• However, the benefits of using radiation in medicine can out way the potential risks

  • The risks posed by the radiation are smaller than the risks associated with leaving the condition untreated

• For example, if a person has a cancerous tumour that is likely to kill them, then it is less of a risk to use radiotherapy than to leave the tumour

Tissue Damage

• Radiation is effectively used to destroy cancerous tumour cells

• However, it can cause damage to healthy tissue if it is not properly targeted

• This is mostly from high-energy radiation such as gamma rays and X-rays

Mutations

• If the atoms that make up a DNA strand are ionised then the DNA strand can be damaged

• If the DNA is damaged then the cell may die, or the DNA may be mutated when it reforms

• If a mutated cell is able to replicate itself then a tumour may form

  • This is an example of cancer, which is a significant danger of radiation exposure

Mutation of a Cell by Ionising Radiation

Diagram showing the damage caused to DNA by ionising radiation. Sometimes the cell is able to successfully repair the DNA, but incorrect repairs can cause a mutation

• Acute radiation exposure can have other serious symptoms:

  • It can cause skin burns, similar to severe sunburn

  • Radiation can reduce the amount of white blood cells in the body, making a person more susceptible to infections by lowering their immune system

• Because of this, it is very important to handle radioactive sources carefully

Safe Storage

• The risks associated with handling radioactive sources can be minimised by following a few simple procedures:

  • Sources must be stored in lead-lined boxes and kept at a distance from people

  • Sources must be handled for the minimum time possible and then returned to their boxes immediately

  • During use, sources should be handled with a pair of tongs at arm’s length

• When using tongs, gloves and safety specs are usually unnecessary when handling radioactive materials, unless there is a risk of the material leaking onto other items

Hazard Symbol for Radioactivity

Whenever you see this symbol, it means a source of ionising radiation is nearby and you should proceed with caution

Disposing of Radioactive Waste

• If an isotope has a long half-life then a sample of it will decay slowly

  • Although it may not emit a lot of radiation, it will remain radioactive for a very long time

• Sources with long half-life values present a risk of contamination for a much longer time

• Radioactive waste with a long half-life is buried underground to prevent it from being released into the environment

Disposal of Radioactive Waste

Radioactive waste with a long half-life must be buried deep underground