Food irradiation

The treatment of food with ionizing radiation has been in practice for nearly a century since the first irradiation process patents were filed in 1905. Regular use of the technology in food processing started in 1963 when the U.S. Food and Drug Administration (FDA) approved the sale of irradiated wheat and wheat flour. Today irradiation treatment is used on a wide variety of food products and is regulated in the United States by the FDA under a Department of Health and Human Services regulation.

Irradiation of food has three main applications: extension of shelf life, elimination of insects, and the destruction of bacteria and other pathogens that cause foodborne illness. This final goal may have the most far-reaching implications for Americans; the U.S. Centers for Disease Control (CDC) estimate that 76 million Americans get sick, and 5,000 die each year from illnesses caused by foodborne microorganisms , such as E. coli, Salmonella, the botulism toxin, and other pathogens responsible for food poisoning .

Irradiation technology involves exposing food to ionizing radiation. The radiation is generated from gamma rays emitted by cobalt-60 or cesium-137, or from x rays or electron beams. The amount of radiation absorbed during irradiation processing is measured in units called RADs (radiant energy absorbed). One hundred RADs is equivalent to one Gray (Gy). Depending on the food product being irradiated, treatment can range from 0.05 to 30 kGy. A dosimeter, or film badge, verifies the kGy dose. The ionizing radiation displaces electrons in the food, which slows cell division and kills bacteria and pests.

The irradiation process itself is relatively simple. Food is packed in totes or containers, which are typically placed on a conveyer belt. Beef and other foods that require refrigeration are loaded into insulated containers prior to treatment. The belt transports the food bins through a lead-lined irradiation cell or chamber, where they are exposed to the ionizing radiation that kills the microorganisms. Several trips through the chamber may be required for full irradiation. The length of the treatment depends upon the food being processed and the technology used, but each rotation takes only a few minutes.

The FDA has approved the use of irradiation for wheat and wheat powder, spices, enzyme preparations, vegetables, pork, fruits, poultry, beef, lamb, and goat meat. In 2000, the FDA also approved the use of irradiation to control salmonella in fresh eggs.

Labeling guidelines introduced by the Codex Alimentarius Commission, an international food standards organization sponsored jointly by the United Nations Food and Agricultural Organization (FAO) and the World Health Organization (WHO), requires that all irradiated food products and ingredients be clearly labeled as such for consumers. Codex also created the radura, a voluntary international symbol that represents irradiation. In the United States, the food irradiation process is regulated jointly by FDA and the U.S. Department of Agriculture (USDA). Facilities using radioactive sources such as cobalt-60 are also regulated by the Nuclear Regulatory Commission (NRC. The FDA regulates irradiation sources, levels, food types and packaging, as well as required recordkeeping and labeling. Records must be maintained and made available to FDA for one year beyond the shelf-life of the irradiated food to a maximum of three years. They must describe all aspects of the treatment and foods that have been irradiated must be denoted with the radura symbol and by the statement "Treated with radiation" or "Treated by irradiation". As of 2002, food irradiation is allowed in some 50 countries and is endorsed by the World Health Organization (WHO), and many other organizations.

New legislation entitled the "Farm Security and Rural Investment Act of 2002" (the Farm Bill) passed in May 2002 may soften the food irradiation standards. The Farm Bill calls for the Secretary of Health and Human Services and FDA to implement a new regulatory program for irradiated foods. The program will allow the food industry to instead label irradiated food as "pasteurized" as long as they meet appropriate food safety standards. As of the writing of this entry, these new guidelines had not been implemented.

Food that has been treated with ionizing energy typically looks and tastes the same as non-irradiated food. Just like a suitcase going through an airport x-ray machine, irradiated food does not come into direct contact with a radiation source and is not radioactive. However, depending on the strength and duration of the irradiation process, some slight changes in appearance and taste have been reported in some foods after treatment. Some of the flavor changes may be attributed to the generation of substances known as radiolytic products in irradiated foods.

When food products are irradiated the energy displaces electrons in the food and forms compounds called free radicals. The free radicals react with other molecules to form new stable compounds, termed radiolytic products. Benzene , formaldehyde, and hydrogen peroxide are just a few of the radiolytic products that may form during the irradiation process. These substances are only present in minute amounts, however, and the FDA reports that 90% of all radiolytic products from irradiation are also found naturally in food.

The chemical change that creates radiolytic products also occurs in other food processing methods, such as canning or cooking. However, about 10% of the radiolytic products found in irradiated food are unique to the irradiation process and little is known about the effects that they may have on human health. It should be noted, however, that the World Health Organization, the American Medical Association, the American Dietetic Association, and a host of other professional healthcare organizations endorse the use of irradiation as a food safety measure.

Treating fruit and vegetables with irradiation can also eliminate the need for chemical fumigation after harvesting. Produce shelf life is extended by the reduction and elimination of organisms that cause spoilage. It also slows cell division, thus delaying the ripening process, and in some types of produce irradiation extends the shelf life for up to a week. Advocates of irradiation claim that it is a safe alternative to the use of fumigants, several of which have been banned in the United States.

Nevertheless, irradiation removes some of the nutrients from foods, particularly vitamins A, C, E, and the B-Complex vitamins. Whether the extent of this nutrient loss is significant enough to be harmful is debatable. Advocates of irradiation say the loss is insignificant, and standard methods of cooking can destroy these same vitamins. However, research suggests that cooking an irradiated food may further increase the loss of nutrients.

Critics of irradiation also question the long-term safety of consumption of irradiated food and their associated radiolytic products. They charge that the technology does nothing to address the unsanitary food processing practices and inadequate inspection programs that breed foodborne pathogens.

Even if irradiation is 100% safe and beneficial there are numerous environmental concerns. Many opponents of irradiation cite the proliferation of radioactive material and the environmental hazards. The mining and on-site processing of radioactive materials are devastating to regional ecosystems. There are also safety hazards associated with the transportation of radioactive material, production of isotopes, and disposal.

[Paula Ford-Martin and Debra Glidden ]

RESOURCES

BOOKS

Molins, Ricardo A. Food Irradiation: Principles and Applications. New York: John Wiley and Sons, 2001.

Stuart, Thorne, ed. Food Irradiation (Elsevier Applied Food Science Series). New York: Elsevier, 1992.

PERIODICALS

Ennen, Steve. "Irradiation Plant Gets USDA Approval." Food Processing (March 2001): 90–2.

Louria, Donald. "Food Irradiation: Unresolved Issues." Clinical Infectious Diseases 33 (August 2001): 378–80.

Steele, J. H. "Food Irradiation: A Public Health Challenge for the 21st Century." Clinical Infectious Diseases 33 (August 2001): 376–7.

U.S. General Accounting Office. "Food Irradiation: Available Research Indicates That Benefits Outweigh Risks." GAO Report to Congressional Requesters. GAO/RCED-00-217 (August 2000).

OTHER

U.S. Department of Agriculture, Food Safety and Inspection Service. Irradiation of Meat and Poultry Products. [cited July 2002]. <http://www.fsis.usda.gov/OA/topics/irrmenu.htm>.

U.S. Department of Agriculture, Food Safety and Inspection Service. "Irradiation of Meat Food Products; Final Rule." Federal Register 64, no. 246 (December 23, 1999): 72150–66.

ORGANIZATIONS

The Food Irradiation Website, <http://www.food-irradiation.com>

National Food Processors Association, 1350 I Street, NW Suite 300, Washington, DC USA 20005 (202) 639-5900, Fax: (202) 639-5932, Email: [email protected], <http://www.nfpa-food.org>

Public Citizen, Critical Mass Energy & Environmental Program, 1600 20th St. NW, Washington, DC USA 20009 (202) 588-1000, Email: [email protected], <http://www.citizen.org/cmep/foodsafety/food_irrad>