What is the use of radioactivity in food preservation?

Radiation, or irradiation, is used to kill microorganisms and parasites that would otherwise cause food to spoil, thereby greatly increasing that food’s shelf life. Irradiation also kills off the bacteria that causes salmonella and E. coli poisoning in humans who ingest improperly treated or maintained foods. When used in proper doses, the radiation, in the form of gamma rays, quickly dissipates and is not present in the food when it is later sold or consumed.
The idea of irradiating produce and meats intended for human or even animal consumption is frightening to many people. The association of radiation with cancers and other illnesses is well founded. Radiation is also associated with lethal military applications, such as in the effects of nuclear weapons, the environmental testing of which in the 1940s and 1950s resulted in numerous cases of debilitating and critical illnesses. And, of course, the dangers of a nuclear reactor accident, such as the one that occurred at Three Mile Island, Pennsylvania, in March 1979 and, far more famously, the one that occurred at the Chernobyl nuclear reactor plant in Ukraine in April 1986, understandably influence popular perceptions of radioactivity.
Radiation is a known substance, however, and is routinely used in medical diagnoses and treatments, at carefully monitored levels, and its application in the food preservation industry is similarly strictly regulated. The kind of radiation used in food preservation has a very short life span and poses no hazards to animals and humans.
http://www.radioactivity.eu.com/site/pages/Food_Preservation.htm

https://www.ncbi.nlm.nih.gov/pubmed/9414630