Food Irradiation

Background and Current Practices
Food Irradiation: What Is It?
Benefits of Food Irradiation
Food Irradiation Applications
Federal Agency Regulation
Safety and Nutrition: Dispelling Myths
Organizations Supporting Food Irradiation
Consumer Opposition

Background and Current Practices

Many food safety experts believe that irradiation can be a critical tool in helping to control foodborne pathogens and that it should be incorporated into a comprehensive program to enhance food safety (see Selected Reading: Osterholm 2004, Osterholm 1997). Irradiation does not replace any of the current measures to reduce foodborne diseases; rather it provides a substantial reduction in any bacterial or parasitic contamination that occurs on or in the product prior to irradiation.

Viruses, bacterial spores, some molds and yeasts, mycotoxins produced by certain types of bacteria and mold, and prion particles are highly resistant to irradiation.

The irradiation process is not suitable for all products. Foods with high fat content, such as fatty fish and some dairy products, may develop off-odors and tastes because of the acceleration of rancidity. Also, foods with high protein content, such as meat and poultry, can have changes in flavor and odor after irradiation. These effects can be substantially minimized by irradiating at chilled or frozen temperatures and by highly regulating the irradiation dosage.

To date, only limited amounts of irradiated foods have been sold in the United States (see Selected Reading: US General Accounting Office 2000). Examples include:

• In 1999, irradiated spices, herbs, and dry vegetable seasonings were the largest category of foods to be irradiated; about 95 million pounds of these products were irradiated.
• A limited amount of irradiated fresh fruit, vegetables, and poultry have been available to consumers in Florida and several Midwestern states.
• In 2000, irradiated frozen ground beef patties became available in markets throughout the country.

Chronology of Food Irradiation Events in the United States*
Year	Event
1905	Scientists received patents for food preservative process that uses ionizing radiation to kill bacteria in food.
1921	US patent granted for process to kill Trichinella spiralis in meat by using x-ray technology.
1953-1980	US government formed National Food Irradiation Program. Under program, US Army and Atomic Energy Commission sponsored many research projects on food irradiation.
1958	Food, Drug, and Cosmetic Act (administered by FDA) amended and defined sources of radiation intended for use in processing food as new food additive.
1963	FDA approved irradiation to control insects in wheat and flour.
1964	FDA approved irradiation to inhibit sprouting in white potatoes.
1964-1968	US Army and Atomic Energy Commission petitioned FDA to approve irradiation of several packaging materials.
1966	US Army and USDA petitioned FDA to approve irradiation of ham.
1971	FDA approved irradiation of several packaging materials based on 1964-68 petition by US Army and Atomic Energy Commission.
1976	US Army contracted with commercial companies to study wholesomeness of irradiated ham, pork, and chicken.
1980	USDA inherited US Army's food irradiation program.
1985	FDA approved irradiation at specific doses to control T spiralis in pork.
1986	FDA approved irradiation at specific doses to delay maturation, inhibit growth, and disinfect foods, including vegetables and spices. Federal Meat Inspection Act (administered by USDA) amended to permit gamma radiation to control T spiralis in fresh or previously frozen pork.
1990	FDA approved irradiation for poultry to control Salmonella and other foodborne bacteria.
1992	USDA approved irradiation for poultry to control Salmonella and other foodborne bacteria.
1997	FDA's regulations amended to permit ionized radiation as source of radiation to treat refrigerated or frozen uncooked meat, meat byproducts, and certain food products to control foodborne pathogens and to extend shelf life.
2000	USDA's regulations amended to allow irradiation of refrigerated and frozen uncooked meat, meat byproducts, and certain other meat food products to reduce levels of foodborne pathogens and to extend shelf life. FDA's regulations amended to permit irradiation of fresh shell eggs to control Salmonella.
2002	2002 Farm Bill directs USDA to not prohibit the use of approved food safety technologies on foods purchased for the National School Lunch Program
2004	As if Jan 1, schools are able to purchase irradiated ground beef from USDA for National School Lunch Program
Abbreviations: FDA, Food and Drug Administration; USDA, US Department of Agriculture. *See Selected Reading: US General Accounting Office 2000.

Back to top

Food Irradiation: What Is It?

Food irradiation is the process of applying electromagnetic radiation, a form of energy that includes visible and ultraviolet light, to foods. There are three source of radiation:

• Gamma rays (uses radioactive isotopes [eg, cesium 137, cobalt 60])
• High-energy electrons
• X-rays

While the three types of ionizing radiation have the same effects on food, there are some differences in how they work. For example, electron beams and x-ray radiators are operated by electricity and do not use radioactive isotopes (eg, cobalt 60). Current food production and processing industry plans for implementing food irradiation primarily involve electron beams and x-ray radiators. The radiation sources used in food irradiation do not make food radioactive.

There are different modes of food irradiation; the mode used depends on the purpose:

• Low doses (<1 kilogray [kGy]) are used to control insects, trichinae (parasitic worms) in pork, and ripening or sprouting of fruits and vegetables.
• Medium doses (1-10 kGy) are used to control both spoilage-causing microorganisms (such as molds) and bacterial pathogens (such as Campylobacter, Escherichia coli O157:H7, and Salmonella). Low to medium doses also are effective against foodborne protozoans such as Cyclospora.
• High doses (>10 kGy) are used to control microbial contamination of spices and, with only enough heating to deactivate enzymes, to make other foods storable at room temperature (ie, shelf-stable). High doses also can significantly reduce foodborne viruses.

Back to top

Benefits of Food Irradiation

• Irradiation can reduce the presence of foodborne pathogens, according to numerous studies conducted worldwide for over 50 years. Irradiation within approved dosages has been shown to destroy at least 99.9% of common foodborne pathogens (eg, Salmonella, Campylobacter, E coli O157:H7, Listeria monocytogenes), which are associated with meat, poultry, and secondary contamination of fresh produce.
• At approved doses, irradiation does not sterilize food. However, it prolongs shelf life of many fruits and vegetables by reducing growth of spoilage bacteria and mold and by inhibiting sprouting and maturation. As a result, products can be harvested when fully ripened and can be transported and displayed for longer periods while maintaining desirable sensory qualities.
• Irradiation is an effective means to decontaminate certain food products, thereby eliminating or reducing the use of toxic or environmentally harmful fumigants.
• Irradiation can be used as a pest-control treatment on quarantined fruits and vegetables to prevent the importation of harmful pests.

Back to top

Food Irradiation Applications

A number of food irradiation applications, which are aimed at improving food safety and reducing food spoilage, have been identified. These are outlined in the table below.

Applications of Food Irradiation
Type of Food	Application	Recommended Doses of Irradiation
Poultry and poultry products, including mechanically recovered meat	To reduce numbers of Salmonella, Campylobacter, and other bacterial foodborne pathogens	Up to 3 kGy (fresh) and up to 7 kGy (frozen)
Irradiation of red meats, including hamburger meat	To reduce numbers of Escherichia coli O157:H7 and other bacterial foodborne pathogens	Up to 4.5 kGy (fresh) and up to 7 kGy (frozen)
Dried herbs and spices	To reduce levels of contaminating microorganisms and reduce chances of survival of bacterial foodborne pathogens	Up to 10 kGy
Imported seafood (eg, warm-water prawns and other shellfish)	To improve microbiologic safety	Up to 3 kGy
Certain fruits and vegetables	To reduce numbers of microorganisms, particularly those that cause spoilage	Up to 2 kGy
Bulbs and tubers, such as potatoes and onions	To prevent sprouting	1 kGy
Cereals, grains, and certain fruits	As quarantine measure to kill insects	1 kGy
Various food items, such as "ready meals"	High-dose irradiation to produce sterile foods	>45 kGy under frozen conditions to lessen adverse sensory effects (but not stored frozen)
Abbreviation: kGy, kilogray.

Back to top

Federal Agency Regulation

Irradiation was first approved in the United States in 1963 for use on wheat flour to control mold. For meat and poultry, the use of food irradiation requires approval of both the Food and Drug Administration (FDA) and the US Department of Agriculture (USDA); the latter agency is responsible for developing procedures that govern the actual irradiation process. The Nuclear Regulatory Commission regulates facilities that use cesium 137 or cobalt 60 (ie, gamma rays); however, electron beam and x-ray sources are monitored by the FDA as well as approved state authorities that regulate other medical, dental, and industrial uses of these technologies.

The FDA requires irradiated foods to have the international radura symbol (green petals in broken circle) and the written statement "treated by irradiation" or "treated with radiation" clearly displayed on the packaging.

Under US law, irradiation is termed an "additive." The US government is the only government in the world that has categorized irradiation as an additive and regulates it as such. The word "additive" ordinarily refers to a substance (ie, to matter, not to energy); however, food irradiation does not add any substances to food.

Food Products Approved for Irradiation in the United States*
Food Product	Agency/Approval Date	Purpose of Irradiation	Maximum Permitted Dosage (kGy)
Wheat and wheat powder	FDA/Aug 21, 1963	Insect deinfestation	0.20-0.50
White potatoes	FDA/July 8, 1964	Inhibit ion of sprout development	0.05-0.15†
Spices and dry vegetables	FDA/July 5, 1983	Microbial disinfection and insect deinfestation‡	10.0
Dry or dehydrated enzyme preparations	FDA/June 10, 1985	Microbial disinfection	10.0
Pork carcasses or fresh, nonheated processed cuts	FDA/July 22, 1985	Control of Trichinella spiralis	0.30-1.00
Fresh foods	FDA/Apr 18, 1986	Delay of maturation	1.0
Dry or dehydrated aromatic vegetable substances§	FDA/Apr 18, 1986	Microbial disinfection	30.0
Fresh, frozen, uncooked poultry	FDA/May 2, 1990 USDA/Oct 21, 1992	Control of foodborne pathogens	3.0
Refrigerated and frozen uncooked beef, lamb, goat, and pork	FDA/Dec 3, 1997 USDA/Feb 22, 2000	Control of foodborne pathogens and extended shelf life	4.5 (refrigerated) 7.0 (frozen)
Fresh shell eggs	FDA/July 21, 2000	Control of Salmonella	3.0
Abbreviations: FDA, Food and Drug Administration; kGy, kilogray; USDA, US Department of Agriculture. *See Selected Reading:  General Accounting Office 2000. †Maximum dose increased from 0.10 to 0.15 on Nov 9, 1965. ‡Insect deinfestation approved in June 1984. §Refers to substances used as ingredients for flavoring or aroma (eg, culinary herbs, seeds, spices, vegetable seasonings); includes turmeric and paprika when used as color additives. Source: 21 CFR 179.26 (Apr 1, 1999, ed) and FDA and USDA/Food Safety Inspection Service (FSIS) officials.

Back to top

Safety and Nutrition: Dispelling Myths

Despite the benefits of irradiation, the widespread use of irradiated food hinges largely on consumer confidence in the safety and wholesomeness of these products. The cumulative evidence from more than four decades of research carried out in laboratories in the United States, Europe, and other countries worldwide indicates that irradiated food is safe to eat. Research to date has demonstrated the following:

• Irradiated food is not radioactive.
• Radioactivity in irradiated foods is not seen as a concern because the energy in the currently approved radiation sources (cobalt 60, cesium 137, electron beams, and x-rays) is too low to induce radioactivity.
• According to the International Consultative Group on Food Irradiation (see Related Links), irradiation cannot increase the normal trace amounts of background radioactivity of food at approved energy levels no matter how long the food is exposed to the radiation source or how much of the energy dose is absorbed.
• There is no evidence of toxic substances resulting from food irradiation.
• Evidence from numerous studies conducted worldwide over the past 50 years indicates that the compounds formed in irradiated food are generally the same as those produced during cooking, canning, pasteurization, and other forms of food preparation and that any differences do not put consumers at risk.
• Three United Nations agencies (the Food and Agriculture Organization [FAO], the World Health Organization [WHO], and the International Atomic Energy Agency [IAEA]) convened joint expert committees on the wholesomeness of irradiated foods in 1964, 1969, 1976, and 1980 to evaluate studies on the safety of irradiated foods and other irradiation-related issues. These committees' evaluations, along with independent evaluations by experts in Denmark, France, the Netherlands, Japan, the United Kingdom, and the United States, found no toxic effects as a result of consumption of irradiated food.
• In 1992, WHO had an expert committee evaluate all the literature and data available since 1980 (more than 500 studies) on the safety of irradiated foods. This committee reiterated earlier findings that food irradiation causes no toxicologic, microbiologic, or nutritional problems that adversely affect human health.
• The FDA has found no evidence or reason to expect that irradiation produces more virulent pathogens among those that survive irradiation treatment. In fact, pathogenic bacteria that survive irradiation are destroyed at lower cooking temperatures than those that have not been irradiated.
• Food irradiation will not have significant impact on nutrition.
• While some nutrient losses are associated with irradiation, they are less than those associated with cooking or many other food-processing methods, according to the Institute of Food Science & Technology's expert panel on food safety and nutrition (see Selected Reading: Institute of Food Science & Technology 1998).
• Carbohydrates, proteins, and fats (the main components of food) are not significantly affected by irradiation doses even greater than those currently approved by FDA.
• Food processors minimize nutrient loss by irradiating food in a cold or frozen state and under reduced levels of oxygen.
• Some vitamin loss is associated with irradiation, and certain vitamins, such as thiamine (B₁), ascorbic acid (C) and alpha-tocopherol (E), are more affected by irradiation than others. However, according to the Institute of Food Technologists, it is highly doubtful that there would ever be any vitamin deficiency resulting from the eating of irradiated food. For example, thiamin is the most radiation-sensitive, water-soluble vitamin. With regard to this vitamin, the American Dietetic Association's (ADA's) position statement on food irradiation notes that FDA evaluated an extreme case in which all meat, poultry, and fish were irradiated at the maximum permissible dose under conditions resulting in the maximum destruction of thiamin (see Related Links: ADA: Food Irradiation). Even in these circumstances, average thiamin intake was above the Recommended Dietary Allowance, leading FDA to conclude that there was no deleterious effect on the total dietary intake of thiamin as a result of irradiated foods.
• In its 1980 evaluation of food irradiation, the joint expert committee convened by FAO, WHO, and IAEA concluded that irradiation caused no special nutritional problems in food. Another meeting of experts in 1997, organized by the same three international organizations, concluded that even high doses of irradiation (ie, over 10 kGy) would not result in nutrient losses that could adversely affect a food's nutritional value.
• Food irradiation plants are safe for workers. There has not been a fatal worker-related accident involving an irradiation facility in the United States to date, despite the fact that more 40 irradiation facilities process large volumes of medical equipment and disposable consumer goods such as bandages and tampons.

Back to top

Organizations Supporting Food Irradiation

Many prominent health-related and scientific organizations have agreed that food irradiation is an effective tool for enhancing food safety. Trade groups such as the American Meat Institute, the Grocery Manufacturers of America, and the National Food Processors Association also support irradiation. In addition, nearly 40 countries, including the United States, Canada, the United Kingdom, France, Germany, the Netherlands, South Africa, Argentina, Brazil, China, India, and Russia, have approved food irradiation for certain types of food.

Scientific and Health-Related Organizations That Consider Food Irradiation Safe

US Government Agencies

• US Department of Agriculture • United States Public Health Service, including the Centers for Disease Control and Prevention • Prevention and the Food and Drug Administration

US Scientific and Health-Related Organizations

• American Dietetic Association • American Medical Association • American Veterinary Medical Association • Council for Agricultural Science and Technology • Institute of Food Technologists • National Association of State Departments of Agriculture • Council of State and Territorial Epidemiologists • Infectious Diseases Society of America

International Scientific and Health-Related Organizations

• Scientific Committee of the European Union Food and Agriculture Organization • International Atomic Energy Agency • World Health Organization • Codex Alimentarius Commission

Back to top

Consumer Opposition

Several consumer groups, such as Food and Water, Inc, and Public Citizen, strongly oppose food irradiation. However, the arguments presented against irradiation by these groups have not been supported through a peer-review process or government agency review. One argument often presented is that the use of irradiation will allow for "dirty" meat, poultry, or produce to be processed and sold to consumers. However, increased contamination, including additional contamination by organic material, would require higher doses of irradiation for eradication, thus increasing the possibility of taste or odor concerns, a fact that would dissuade food companies from relaxing standards. It is important to have a high-quality product, with minimal contamination, for irradiation to work most effectively both in terms of food safety and consumer satisfaction.

Health professionals can find an excellent fact sheet addressing irradiation and the concerns expressed by consumer critics on the Iowa State University website (see Related Links: Iowa State University).