Irradiation

Irradiation is the process by which an object is exposed to radiation. The exposure can originate from various sources, including natural sources. Most frequently the term refers to ionizing radiation, and to a level of radiation that will serve a specific purpose, rather than radiation exposure to normal levels of background radiation. The term irradiation usually excludes the exposure to non-ionizing radiation, such as microwaves from cellular phones or electromagnetic waves emitted by radio and TV receivers and power supplies.

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 Diagnostic Imaging and cancer therapy.

Ion implantation
Ion irradiation is routinely used to implant impurity atoms into materials, especially semiconductors, to modify their properties. This process, usually known as ion implantation, is a very important step in the manufacturing of silicon integrated circuits.

Ion irradiation
The irradiation of solids by swift heavy ions from particle accelerators induces ion tracks which can be used fornanotechnology.

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 program "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. 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. Appropriate irradiation doses are also used to produce sterile insects to be used in the sterile insect technique.

The U.S. Department of Agriculture's (USDA) Food Safety and Inspection Service (FSIS) recognizes irradiation as an important technology to protecting consumers. Fresh meat and poultry including whole or cut up birds, skinless poultry, pork chops, roasts, stew meat, liver, hamburgers, ground meat, and ground poultry are approved for irradiation.

Assassination
Gheorghe Gheorghiu-Dej died of lung cancer in Bucharest on March 19, 1965. Some claim that he was intentionally irradiated during a visit to Moscow, due to his political stance.

In 1999, an article in Der Spiegel alleged that the East German MfS intentionally irradiated political prisoners with high-dose radiation, possibly to provoke cancer in them.