Dangers of Radioactivity (CIE IGCSE Physics: Co-ordinated Sciences (Double Award))

• Ionising nuclear radiation can damage living things such as human cells and tissues at high doses:
• This can include:
  • Cell death
  • Mutations
  • Cancer

• 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 is replicated
• If a mutated cell replicates itself then a tumour may develop
  • This is an example of cancer, which is a significant danger of radiation exposure

Ionising DNA is a danger of radioactivity

Diagram showing the damage caused to DNA by ionising radiation. Sometimes the cell is able to repair the DNA during replication successfully, 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

• Safety precautions for all ionising radiation include:
• • reducing exposure time
  • increasing the distance between the source and living tissue
  • using shielding to absorb radiation

Reducing exposure time reduces the dangers of radioactivity

• Limiting the amount of time spent near a radioactive source reduces the amount of radiation dose received
• The amount of radiation received by a person is called the dose and is measured in sieverts (Sv)
• One sievert is a very big dose of radiation
  • It would cause acute radiation poisoning

Increasing the distance reduces the dangers of radioactivity

• Increasing the distance the radiation is away greatly reduces the size of the dose received
  • Using tongs instead of your hand when handling a radioactive source can help with this
• Constructing nuclear power plants in remote areas increases their distance from people if there is a problem
• Burying nuclear waste far from places where people live also increases the distance to people

Shielding reduces the dangers of radioactivity

• Radiation shielding is a barrier placed between a radiation source and a person or area to protect them
  • The purpose of shielding is to limit exposure to radiation at a certain location or time
• Barriers absorb the energy from radioactive sources
• Barriers are normally made of lead, water or concrete
  
  • People handling radioactive sources should wear a lead apron to reduce their exposure
• When X-rays are taken:
  • the area around where the image is needed is shielded
  • the radiologist stands behind a barrier or leaves the room

Reducing the dangers of radiation for a radiologist

A radiologist can stand behind a lead barrier to reduce the amount of radiation they are exposed to