Irradiation is the process by which an item is exposed to radiation. The exposure can be intentional, sometimes to serve a specific purpose, or it can be accidental. In common usage the term refers specifically to ionizing radiation, and to a level of radiation that will serve that specific purpose, rather than radiation exposure to normal levels of background radiation or abnormal levels of radiation due to accidental exposure.
Small doses of radiation may be used to remove bacteria in food, or other organic material, including blood.
If administered at appropriate levels, all of these forms of radiation can be used to sterilize objects, a technique used in the production of medical instruments and disposables, such as syringes as well as in the disinfestation and sterilization of food. Irradiation can furthermore be used in cross-polymerization of plastics or to improve material qualities of semi-precious stones. Irradiation is also employed to prevent sprouting of certain cereals, onions, potatoes and garlic. During the 2001 anthrax attacks, the US Postal Service irradiated mail to protect members of the US government and other possible targets. This can be of some concern to people, including artists; according to the ART in Embassies programme "incoming mail is irradiated, and the process destroys slides, transparencies and disks."