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Irradiation
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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.
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Encyclopedia
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. This term also applies to 'non-ionizing radiation as microwaves or to low frequency (50/60 Hz power supply), high frequency (as cellular phones, radio and TV transmissions).
Applications
Sterilization
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. Small doses of ionizing radiation (electron beam processing, X-rays and gamma rays) may be used to kill bacteria in food, or other organic material, including blood. Irradiation also includes (by the principle) microwave heating. Food irradiation, while effective, is seldom used due to public relations problems.
Medicine
It is also used in cancer therapy.
Industrial chemistry
Irradiation can furthermore be used in cross-linking of plastics or to improve material qualities of semi-precious stones. Due to its efficiency, electron beam processing is often used in the irradiation treatment of polymer-based products to improve the mechanical, thermal, and chemical properties, and often adding unique properties. Cross-linked polyethylene pipe (PEX), high-temperature products such as tubing and gaskets, wire and cable jacket curing, curing of composite materials, and crosslinking of tires are a few examples.
Security
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."
Agriculture
After its discovery by Lewis Stadler at the University of Missouri, irradiation of seed and plant germplasm has resulted in creating many of the most widely grown strains of food crops worldwide. The process, which consists of striking plant seeds or germplasm by radiation in the form of X-rays, UV waves, heavy-ion beams, gamma rays, essentially "mixes" the genes already existing in genome. This does not pose the potentially dangerous consequences to biodiversity caused by genetically modified (GM) plants in which foreign genes are added to the genome of the plant. The UN has been active in this through the International Atomic Energy Agency. Irradiation is also employed to prevent sprouting of certain cereals, onions, potatoes and garlic.
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