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| Fig. 1: Co-60 Irradiator. (Source: Wikimedia Commons) |
In the United States alone, up to 40% of our food goes uneaten. [1] This equates to over $160 billion of food waste a year. [2] Additionally, food frequently causes illnesses as well. According to the CDC, approximately $7 billion a year goes to covering the healthcare costs associated with the 76 million infections, 325,000 hospitalizations and 5,000 deaths that occur because of pathogen-contaminated foods. [3] With a large demand for a solution to reduce this waste and exposure to illness, radiation has stepped up to the challenge.
Food irradiation is a process that exposes food to a measured supply of ionizing radiation in order to reduce microbial load, destroy pathogens, extend a products shelf life, and disinfect various produce. For over 60 years, food irradiation has proven to be an effective food safety measure and the United States Food and Drug Administration (FDA) has approved its use for various food categories. Despite this, controversy of using radiation on food ensues and has impeded it from becoming broadly accepted. [4]
The sterilization industry has developed three different irradiation technology methods to treat food. The first is γ irradiation (GI). GI technology utilizes high energy γ rays emitted by radioactive co-60 (Fig. 1) or Cs-137. These radioactive sources work well because they can be produced in commercial nuclear reactors. They also both have relatively long half-lives which makes them beneficial for commercial installation. When sterilizing products, food is brought to a heavily-shielded chamber and exposed to these γ rays for the appropriate length of time required to complete the goal. These rays are so high energy that they can treat penetrate deeply and treat food that is shipped in bulk on large shipping pallets. [5]
The second form of food irradiation is Electron Beam Irradiation (EBI). EBI differs from γ irradiation because it uses a stream of high energy electrons, or beta rays, to treat food waste. These beta rays are emitted from an electron gun, but the level of penetration the electrons can reach at a time is only several centimeters. For this reason, food being treated by EBI has to be in relatively thin layers. Because the electron source can be switched on and off, no radioactivity is involved. [5]
Out of the three methods, X-irradiation is the most recent form of food treatment technology developed and combines properties of the treatments listed above. X-irradiation works by producing high energy X-rays when an electron beam hits a thin metal foil target. Similar to γ rays, these X-rays can also penetrate food deeply. However because the X-ray source can be switched on and off, it also doesn't use a radioactive source. [5]
Studies have found that radioactivity cannot be induced in foods by treatment with γ rays from Co-60 or Cs-137, electrons of 10 million electron volt (MeV) or lower energy, and X-ray sources of of 5 MeV or lower energy. [6] Despite this, Americans have historically worried about exposing food to any types of rays. Many people worry that it will cause their food to be radioactive and cause diseases like cancer. However, what they do not realize is that irradiation techniques have been used for decades to sterilize many heavily used consumer products like cosmetics, hospital equipment, baby powders, and even astronaut meals. [7] Other opponents state that they are worried that food irradiation will be used as an alternative to proper food-processing plant sanitation and cleanliness products. Another common concern expressed by anti-irradiation groups regards the environmental safety of irradiation facilities. [4]
Despite the skepticism listed above, food irradiation is permitted in over 60 countries and processes approximately 500,000 metric tons of food annually worldwide. [8] Food irradiation is one of the most thoroughly evaluated food process technologies. This technology has allowed for food spoilage to decrease and sterilization to increase, which gives hope that this and future technological developments can diminish the effects of world hunger and illness, especially in the third-world countries where this poses the biggest threat.
© Toni Adeyemi. The author warrants that the work is the author's own and that Stanford University provided no input other than typesetting and referencing guidelines. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
[1] K. D. Hall et al., "The Progressive Increase of Food Waste in America and Its Environmental Impact," PLoS One 4, e7940 (2009).
[2] S. Sengupta, "How Much Food Do We Waste? Probably More Than You Think," New York Times, 12 Dec 17.
[3] "Preliminary FoodNet Data on the Incidence of Infection with Pathogens Transmitted Commonly Through Food - 10 States," U.S. Centers for Disease Control and Prevention, Morbidity and Mortality Weekly Report 59, No. 14, 418 (2010).
[4] J. S. Smith and S. Pillai, "Irradiation and Food Safety," Food Technology Magazine 58, No. 11, 48 (2004).
[5] R. V. Tauxe, "Food Safety and Irradiation: Protecting the Public from Foodborne Infections," Emerg. Infect. Dis. 7, 516 (2001).
[6] D. W. Thayer, "Food Irradiation: Benefits and Concerns," J. Food Quality 13, 147 (1990).
[7] J. P. Sterba, "Irradiated Food: Promise and Controversy," New York Times, 30 Jun 82.
[8] C. M. Deeley et al., "The Development of Food Irradiation To-Date in Asia Pacific, the Americas, Europe and Africa," The 14th International Meeting on Radiation Processing, Kuala Lumpur, February 2006.