AQA GCSE Physics

Revision Notes

4.2.10 Contamination & Irradiation


  • Contamination is defined as:

The unwanted presence of materials containing radioactive atoms on other materials

  • A substance is only radioactive if it contains radioactive atoms that emit radiation
  • Contamination occurs when a radioactive isotope gets onto a material where it should not be
    • This is often due to a radiation leak
  • As a result of this, the small amounts of the isotope in the contaminated areas will emit radiation and the material becomes radioactive

The Assassination of Alexander Litvinenko

  • Contamination is almost always a mistake or an accident
    • However, in 2006 a former Russian spy was poisoned by a radioactive isotope
  • His name was Alexander Litvinenko and he was contaminated with the isotope polonium-210
    • He died because of the poisoning

Poison tea, downloadable IGCSE & GCSE Physics revision notes

It is believed that the polonium-210 that poisoned Alexander Litvinenko was secretly put into a cup of tea he was drinking


  • Irradiation is defined as:

The process of exposing a material to alpha, beta or gamma radiation

  • Irradiating a material does not make that material radioactive
    • However, it can kill living cells

Radiation-Hazard, IGCSE & GCSE Physics revision notes

This sign is the international symbol indicating the presence of a radioactive material

  • Irradiation can be used as a method of sterilisation:
    • Surgical equipment is irradiated before being used in order to kill any micro-organisms on it before surgery
    • Food can be irradiated to kill any micro-organisms within it
    • This makes the food last longer without going mouldy

Exam Tip

Irradiation and contamination are very commonly confused.

Remember that something is radioactive only if it contains radioactive atoms. This can only occur from contamination, not from irradiation!

Author: Katie

Katie has always been passionate about the sciences, and completed a degree in Astrophysics at Sheffield University. She decided that she wanted to inspire other young people, so moved to Bristol to complete a PGCE in Secondary Science. She particularly loves creating fun and absorbing materials to help students achieve their exam potential.

Join Save My Exams

Download all our Revision Notes as PDFs

Try a Free Sample of our revision notes as a printable PDF.

Join Now
Already a member?
Go to Top