The Physics Question Bank

Contamination and irradiation are often mixed up, but they mean different things.

Contamination is when unwanted radioactive material gets onto or inside something.

For example, radioactive dust could get onto a person’s skin, clothing, food or equipment.

The danger is that the radioactive material stays there and keeps giving out radiation. This means the person or object can continue to be irradiated until the contamination is removed or the material decays.

Contamination inside the body is especially dangerous. If radioactive material is breathed in or swallowed, it can damage cells from very close range.

Irradiation is when something is exposed to radiation from a radioactive source.

The radioactive source does not get onto or inside the object or person.

For example, a person standing near a gamma source may be irradiated by gamma radiation.

When the source is removed, the irradiation stops.

Irradiation does not make the object radioactive.

The key difference is this:

Contamination means radioactive material is present on or inside something.

Irradiation means radiation has reached something, but the radioactive material has not been transferred.

AQA GCSE 4 mark answer

Contamination is when unwanted radioactive material gets onto or inside an object or person. The material stays there and continues to emit radiation, so it can keep irradiating cells. Irradiation is when an object or person is exposed to radiation from a radioactive source. Irradiation does not make the object radioactive and stops when the source is removed.