Irradiation is the process by which an object is exposed toradiation. Anirradiator is a device used to expose an object to radiation,[1] most oftengamma radiation,[2] for a variety of purposes. Irradiators may be used for sterilizing medical and pharmaceutical supplies, preserving foodstuffs, alteration of gemstone colors, studying radiation effects, eradicating insects through sterile male release programs, or calibratingthermoluminescent dosimeters (TLDs).[3]
The exposure can originate from various sources, including natural sources. Most frequently the term refers toionizing radiation, and to a level of radiation that will serve a specific purpose, rather than radiationexposure to normal levels ofbackground radiation. The term irradiation usually excludes the exposure to non-ionizing radiation, such asinfrared,visible light,microwaves fromcellular phones orelectromagnetic waves emitted by radio and television receivers and power supplies.
If administered at appropriate levels, all forms ofionizing radiation cansterilize objects, including medical instruments, disposables such assyringes, andsterilize food. Ionizing radiation (electron beams,X-rays andgamma rays)[4] may be used to kill bacteria in food or other organic material, including blood.[citation needed]Food irradiation, while effective, is seldom used due to problems with public acceptance.[5]
Irradiation is used indiagnostic imaging,cancer therapy andblood transfusion.[6]
In 2011 researchers found that irradiation was successful in the noveltheranostic technique involving co-treatment withheptamethine dyes to elucidate tumor cells and attenuate their growth with minimal side effects.[7][8]
Ion irradiation is routinely used to implant impuritiesatoms into materials, especiallysemiconductors, to modify their properties. This process, usually knownasion implantation, is an important step in the manufacture of siliconintegrated circuits.[9]
Ion irradiation means in general usingparticle accelerators to shoot energetic ions on a material.Ion implantation is a variety of ion irradiation, as isswift heavy ions irradiation fromparticle accelerators inducesion tracks that can be used fornanotechnology.[10][11]
 A B B B C C  A Initial (2×2 mm size) B Irradiated by different doses of 2 MeV electrons C Irradiated by different doses and then annealed at 800 °C (1,470 °F) |
The irradiation process is widely practiced injewelry industry[12] and enabled the creation of gemstone colors that do not exist or are extremely rare in nature.[13] However, particularly when done in anuclear reactor, the processes can make gemstones radioactive. Health risks related to the residual radioactivity of the treated gemstones have led to government regulations in many countries.[13][14]
Irradiation is used tocross-linkplastics. Due to its efficiency,electron beam processing is often used in the irradiation treatment of polymer-based products to improve their mechanical, thermal, and chemical properties, and often to add 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.
After its discovery by Lewis Stadler at theUniversity of Missouri, irradiation ofseed and plantgermplasm has resulted in creating many widely-growncultivars offood crops worldwide.[15] The process, which consists of striking plant seeds or germplasm with radiation in the form ofX-rays,UV waves,heavy-ion beams, orgamma rays, essentially induce lesions of theDNA, leading to mutations in thegenome. The UN has been an active participant through theInternational Atomic Energy Agency. Irradiation is also employed to prevent the sprouting of certaincereals,onions,potatoes andgarlic.[16] Appropriate irradiation doses are also used to produce insects for use in thesterile insect technique of pest control.[17]
TheU.S. Department of Agriculture's (USDA) Food Safety and Inspection Service (FSIS) recognizes irradiation as an important technology toprotect consumers. Freshmeat andpoultry including whole or cut up birds, skinless poultry,pork chops,roasts,stew meat, liver,hamburgers,ground meat, and ground poultry are approved for irradiation.[18]
Gheorghe Gheorghiu-Dej, who died of lung cancer in Bucharest on March 19, 1965, may have been intentionally irradiated during a visit to Moscow, due to his political stance.[19]
In 1999, an article inDer Spiegel alleged that the East GermanMfS intentionally irradiated political prisoners with high-dose radiation, possibly to provoke cancer.[20][21]
Alexander Litvinenko, a secret serviceman who was tackling organized crime in Russia, was intentionally poisoned withpolonium-210; the very large internal doses of radiation he received caused his death.
In thenuclear industry, irradiation may refer to the phenomenon of exposure of the structure of anuclear reactor to neutron flux, making the materialradioactive and causingirradiation embrittlement,[22][23] or irradiation of thenuclear fuel.
During the2001 anthrax attacks, theUS Postal Serviceirradiated mail to protect members of the US government and other possible targets. This was of some concern to people who send digital media through the mail, including artists. According to the ART in Embassies program, "incoming mail is irradiated, and the process destroys slides, transparencies and disks."[citation needed]
This article incorporatespublic domain material from websites or documents of theUnited States government.
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