Irradiation and contamination


Shining visible radiation from a torch beam onto a hand lights the hand up because the hand has been exposed to light.

Exposing objects to beams of radiation is called irradiation. The term applies to all types of radiation, including radiation from the nuclei of atoms.

Irradiation from radioactive decay can damage living cells. This can be put to good use as well as being a hazard.


Contamination occurs if an object has a radioactive material introduced into it. An apple exposed to the radiation from cobalt-60 is irradiated, but an apple with cobalt-60 injected into it is contaminated.

As with irradiation, contamination can be very useful as well as being potentially harmful.

Irradiation versus contamination

The two processes of irradiation and contamination are often confused. However, they are very different and useful in their own right.

Occurs when an object is exposed to a source of radiation outside the objectOccurs if the radioactive source is on or in the object
Doesn't cause the object to become radioactive A contaminated object will be radioactive for as long as the source is on or in it
Can be blocked from the object with suitable shieldingOnce an object is contaminated, the radiation cannot be blocked from the object
Stops as soon as the source is removed It can be very difficult to remove all of the contamination