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Food irradiation

Position of ADA

J Am Diet Assoc. 2000;100:246-253.


Food Irradiation Can Enhance Safety of Nation's Food Supply
9jan96 ADA Press Release

Food irradiation has been identified as a safe technology to reduce the risk of foodborne illness as part of high-quality food production, processing, handling, and preparation. Food irradiation's history of scientific research, evaluation, and testing spans more than 50 years. The process has been approved by more than 40 countries around the world and it has been endorsed or supported by numerous national and international food and health organizations and professional groups. Food irradiation utilizes a source of ionizing energy that passes through food to destroy harmful bacteria and other organisms. Often referred to as "cold pasteurization," food irradiation offers negligible loss of nutrients or sensory qualities in food as it does not substantially raise the temperature of the food during processing. Food irradiation does not replace proper food production, processing, handling, or preparation, nor can it enhance the quality of or prevent contact with foodborne bacteria after irradiation. In the United States, manufacturers are required to identify irradiated food sold to consumers with an international symbol (Radura) and terminology describing the process on product labels. In addition, food irradiation facilities are thoroughly regulated and monitored for worker and environmental safety. Members of The American Dietetic Association (ADA) and other food, nutrition, and health professionals have a responsibility to educate consumers, food processors, manufacturers and retailers about the safety and application of the technology. When consumers are educated about food irradiation, many prefer irradiated products because of their increased safety. It is the position of the ADA that food irradiation enhances the safety and quality of the food supply and helps protect consumers from foodborne illness. The ADA encourages the government, food manufacturers, food commodity groups, and qualified food and nutrition professionals to work together to educate consumers about this additional food safety tool and make this choice available in the marketplace. J Am Diet Assoc. 2000;100:246-253.

The American Dietetic Association (ADA) and qualified dietetics professionals have a responsibility to educate consumers on issues related to food and nutrition. One issue of importance to professionals and consumers is food irradiation. Food irradiation offers a solution for addressing the growing concerns associated with food safety.


It is the position of The American Dietetic Association (ADA) that food irradiation enhances the safety and quality of the food supply and helps protect consumers from foodborne illness. The ADA encourages the government, food manufacturers, food commodity groups, and qualified food and nutrition professionals to work together to educate consumers about this additional food safety tool and to make this choice available in the marketplace.

General Overview

Although the US food supply has achieved a high level of safety, microbiological risks exist. Because foods may contain harmful bacteria, mishandling--including improper cooking--can result in foodborne illness. The Centers for Disease Control and Prevention estimates that foodborne bacteria caused 76 million illnesses, 325,000 hospitalizations, and 5,000 deaths in the United States in 1998 (1). Known foodborne pathogens accounted for an estimated 14 million illnesses, 60,000 hospitalizations, and 1,800 deaths. Outbreaks of Escherichia coli 0157:H7 (E coli) from food sources are estimated to cause 62,458 illnesses, 1,843 hospitalizations, and 52 deaths yearly. Four pathogens--Campylobacter spp, Listeria monocytogenes, Salmonella nontyphoidal, and Toxoplasma gondi--are responsible for 3,420,000 illnesses and 1,526 deaths annually. Illnesses and death cost society monetarily and emotionally. The Economic Research Service of the US Department of Agriculture (USDA) estimates the value of a statistical life using the hedonic wage approach; this approach uses labor market data on how much employers must offer in terms of higher wages to induce workers to take a job with some injury risk, and the willingness-to-pay approach as reflected in life insurance premiums and lost productivity (2). The hedonic wage approach estimates a life at $5 million per person, whereas the willingness-to-pay method ranges from $15,000 to $1,979,000, depending on the victim's age. Both estimates undervalue the true costs of foodborne illness to society because they do not include the cost of all complications linked to foodborne illnesses, such as arthritis, meningitis, or Guillain-Barré syndrome. Pasteurization by irradiation has been identified as a solution that enhances food safety through the reduction of potential pathogens and has been recommended as part of a comprehensive program to enhance food safety (3-7).

The Food Irradiation Process

Irradiation exposes food to radiant energy. (See Figure 1 for definitions of food irradiation terminology.) Food is passed through an irradiator--an enclosed chamber--where it is exposed to a source of ionizing energy. The sources of ionizing energy may be gamma rays from cobalt 60 (60Co), cesium 137 (137Cs), x-rays, or electrons generated from machine sources (8,9). In 1999, food irradiation in the United States occurs exclusively from the use of 60Co (10,11), which is contained in stainless steel rods placed in racks (Figure 2). The emitted gamma rays are very short wavelengths, similar to ultraviolet light and microwaves. Because gamma radiation does not elicit neutrons (ie, the subatomic particles that can make substances radioactive), irradiated foods and their packaging are not made radioactive (9,11-13). A self-contained, prefabricated cabinet loaded with 137CS to provide an additional processing option is being developed. Electron beam facilities, widely used to irradiate medical equipment, have been built for food treatment (Figure 3). Energy penetration is about 11/2 inches in food products, so the thickness of items to be treated is limited to about 3 inches with double-sided treatment. A combination electron beam and x-ray facility for food irradiation is being planned for construction in the northeastern United States. Regardless of source, the effect of ionizing energy on food is identical. Energy penetrates the food and its packaging but most of the energy simply passes through the food, similar to the way microwaves pass through food, leaving no residue. The small amount of energy that does not pass through the food is negligible and is retained as heat.

The duration of exposure to ionizing energy, density of food, and the amount of energy emitted by the irradiator determine the amount or dose of radiant energy to which the food is exposed (9,11,12,14). Regulated doses are set at the minimum levels necessary to achieve specified purposes or benefits (Figure 4). Radiation doses allowed by the US Food and Drug Administration (FDA) are the most restrictive of all countries in which irradiation is allowed (11). Low doses (up to 1 kiloGray [kGy]) control the Trichina parasite in fresh pork; inhibit maturation in fruits and vegetables; and control insects, mites, and other arthropod pests in food. Medium doses (up to 10 kGy) control bacteria in meat, poultry, and other foods, and high doses (above 10 kGy) control microorganisms in herbs, spices, teas, and other dried-vegetable substances (15).

Food irradiation does not replace proper food production or handling. Even with treatments that destroy 99.9% of a pathogen, some could still survive (9). Bacteria that cause spoilage are more resistant to irradiation than pathogens and require a higher treatment. Therefore, the handling of foods processed by irradiation should be governed by the same food safety precautions as all other foods. Food irradiation cannot enhance the quality of a food that is not fresh or prevent contamination that occurs after irradiation.

Historical Summary of Food Irradiation

Food irradiation currently has a 50-year history of scientific research and testing, with more than 40 years preceding approval of the process for any foods in the United States. To date, no other food technology has had as long a history of scientific research and testing before gaining approval (11). Research has been comprehensive and has included toxicological and microbiological evaluation, as well as testing for wholesomeness. In 1955, the US Army Medical Department began to assess the safety of types of foods commonly irradiated in the US diet (16). Petitions to the FDA for approval of specific foods for irradiation soon followed; wheat and wheat powder received first approval in 1963 (Figure 4). In the early 1970s, the National Aeronautics and Space Administration adopted the process to sterilize meats for astronauts to consume in space, and this practice has continued (17). The first products approved by the FDA were wheat and white potatoes in the 1960s. During the 1980s, the FDA approved petitions for irradiation of spices and seasonings, pork, fresh fruits, and dry or dehydrated substances. Poultry received FDA approval in 1990; red meats were approved in 1997. Worldwide, 40 countries permit irradiation of food, and more than half a million tons of food are irradiated annually (6,18,19). The United States has approximately 40 licensed irradiation facilities; most are used to sterilize medical and pharmaceutical supplies. Food irradiation has an impressive list of national and international endorsements: ADA, Centers for Disease Control and Prevention, American Council on Science and Health, American Medical Association (AMA), American Veterinary Medical Association, Council for Agricultural Science and Technology, International Atomic Energy Agency, Institute of Food Technologists, Scientific Committee of the European Union, United Nations Food and Agricultural Organization (FAO), and World Health Organization (WHO) (11,12).

Benefits of Food Irradiation

Treating foods with ionizing energy offers many benefits to consumers, retailers, and food manufacturers. The benefits depend on the treatment used (Figure 4). Certainly the most important benefit is improved microbiological quality of food. Additional benefits include the replacement of chemical treatments and extended shelf life (9,11,12,19). The following benefits are specified:

Most spices and herbs are fumigated with ethylene oxide to improve microbiological quality. Irradiation replaces this chemical, which is being phased out for environmental and worker safety reasons.

Because pathogens in raw poultry or meat can be reduced by 99.9% or more by a low "pasteurization" treatment (14), irradiation can help reduce the potential for cross-contamination in homes and foodservice kitchens (eg, schools, industry, groceries, hospitals, restaurants). Irradiation also provides an additional level of safety if food is not fully cooked.

Transport of some fruits and vegetables is restricted or prohibited to prevent the spread of harmful insects such as the Mediterranean fruit fly. Current insect quarantine procedures require harvest and heat treatment of fruit that is not fully ripe. Irradiation is an approved quarantine treatment that results in a higher-quality fruit because it can be used on ripe fruit, does not cause hard spots, and does not increase susceptibility to mold. Additionally, irradiation can be used on fruits that do not tolerate heat treatments. Use of this quarantine method will increase availability of a wider variety and higher quality of tropical and semitropical fruits.

Irradiation can replace chemical fumigants used to protect rice and grain from insect infestation.

Irradiation retards the natural decay of fruit and vegetables, thus extending shelf life.

Irradiation contributes to keeping down food costs as a result of less wastage and extended shelf life.

Because irradiated food is virtually indistinguishable from fresh items (9,13), food can be prepared in the traditional manner. The process can be considered a "win-win" situation for consumers, retailers, and food manufacturers.

Effect of Irradiation on Nutritive Value of Food

Irradiation has been compared to pasteurization because it destroys harmful bacteria. Since irradiation does not substantially raise the temperature of the food being processed, nutrient losses are small and often substantially less than other methods of preservation such as canning, drying, and heat pasteurization and sterilization (8,9,11,12,19). The relative sensitivity of the different vitamins to irradiation depends on the food source, and the combination of irradiation and cooking is not considered to produce losses of notable concern (9).

Proteins, fats, and carbohydrates are not notably altered by irradiation (8,9,13,19). In general, nutrients most sensitive to heat treatment, such as the B vitamins and ascorbic acid, are sensitive to irradiation. Diehl (9) and Thorne (13) compared nutrient retention losses from irradiation with those associated with other traditional methods of preparation. Vitamin losses from pure solutions are larger than losses when the vitamin is in a food material (9). Nutrient losses can be further minimized by irradiating food in an oxygen-free environment or a cold or frozen state (9,13). Fox and coworkers (20) derived a formula to calculate predicted losses in cooked pork and chicken on the basis of data--derived from the second National Health and Nutrition Examination Survey--on quantities of these items in the US diet and irradiation doses allowed by the FDA. Predicted losses of riboflavin and niacin in pork, and of thiamin in both pork and chicken, ranged from 0.01% to 1.5%. Fresh pork, as reported in a study based on the USDA's 1989-1991 Continuing Survey of Food Intake by Individuals (21), provides approximately 4% of the thiamin in a typical US diet, whereas poultry provides approximately 1%. Grain products, by comparison, contribute 46.8% of thiamin in the US diet.

Before approving irradiation of meat, the FDA evaluated an "extreme case" in which all meat, poultry, and fish were irradiated at the maximum permissible dose under conditions that led to maximum destruction of thiamin (22). Even in these extreme and unlikely circumstances, the average thiamin intake would still be above the Recommended Dietary Allowance (RDA) (23) and now the Dietary Reference Intake (DRI) (24). Thus, the FDA concluded there would be no deleterious effect on the total dietary intake of thiamin as a result of irradiating foods. Another study by Fox et al (25) compared radiation reductions in B-vitamin levels in beef, lamb, pork, and turkey. The researchers reported losses of riboflavin that were virtually undetectable in all the tested meats at doses up to 3 kGy. Thiamin losses were detectable, and the losses varied among the meats tested, but the range was narrow, from a low of 8% loss to a high of 16% loss. Earlier reports regarding losses of ascorbic acid in potatoes--as a result of a shift to dehydroascorbic acid--are no longer considered valid because the researchers failed to consider that dehydroascorbic acid also has vitamin activity (9). In a study of the ascorbic acid content of oranges, Nagai and Moy (26) found no significant differences between irradiated and control fruit at dose levels up to 1 kGy throughout a 6-week storage period.

Sensory qualities such as appearance and flavor have been evaluated in the laboratory (9,18,26,27) as well as in market studies with consumers (16,27). Consumers consistently rated irradiated fruit as equal to or better than nonirradiated fruits in appearance, freshness, and taste (16,27,28). However, irradiation may affect the color and odor of meat, depending on the irradiation dose, dose rate, temperature, packaging, and atmosphere during irradiation (29). Irradiated beef becomes a deeper red and pork and poultry become more pink. These changes are more pronounced at higher levels of ionizing energy. When meat is irradiated at low doses under specific conditions--such as low oxygen or no oxygen--with specific packaging such as vacuum sealed or in the frozen state, there is no notable development of off-odors or flavors. Studies have found that flavor in vacuum-packed raw or cured pork is not negatively affected by irradiation and that cooked pork ranks equally with nonirradiated samples for meatiness, freshness, tenderness, juiciness, and overall acceptance (30-32). Irradiation of chicken breast and thigh up to 10 kGy had little effect on sensory acceptability of appearance, odor, texture, and taste (33).

Food Safety

Food safety encompasses enhanced safety as a result of destruction of pathogenic microorganisms, as well as chemical and toxicological safety of foods that have been irradiated. The scientific literature clearly demonstrates that irradiation destroys common enteric pathogens including Campylobacter jejuni, E coli, Listeria monocytogenes, various Salmonella spp, and Staphylococcus aureus associated with meat, poultry, and fresh produce (29,34,35). An irradiation dose of 0.4 kGy destroys Toxoplasma gondi and Cyclospora, the latter of which has been associated with gastroenteritis linked to the ingestion of fresh raspberries, lettuce, and herbs (36). Vibrio infections associated with the consumption of raw molluscans shellfish can be prevented with irradiation pasteurization, but Norwalk-like viruses associated with raw shellfish and hepatitis A virus require higher doses than are approved for meat and poultry pasteurization (37). Irradiation does not protect against bovine spongiform encephalopathy.

Some people are concerned that irradiated food will not show signs of spoilage and people will inadvertently consume a harmful product. As with any food, proper handling and preparation--not taste or smell--ensures food safety. Some people have also inquired about the safety of irradiated food if postirradiation contamination were to occur. Meat or poultry contaminated after irradiation does not spoil more rapidly than a nonirradiated product (38,39). Irradiated and nonirradiated meats challenged with postirradiation application of pathogenic bacteria exhibited spoilage at virtually the same time when held at refrigerator temperatures or temperatures that would normally allow for bacterial growth (40,41). Some people have inquired about the viability of microorganisms that may survive low-dose or medium-dose treatment. The bacteria that survive irradiation are destroyed at a lower cooking temperature than the bacteria that have not been irradiated (42).

When evaluating the safety of irradiation, the FDA did not consider possible benefits to consumers or food processors (22). The agency must identify various effects that can result from irradiating food and assess whether these may pose a human health risk. The FDA review addresses potential toxicity, nutritional adequacy, and potential microbiological risks.

Irradiation does cause chemical changes in food, all of which have been found to be benign. More than 40 years of multispecies, multigenerational animal studies have shown no toxic effects from eating irradiated foods (22,43). Additionally, human volunteers consuming up to 100% of their diets as irradiated food have shown no ill effect (9). Irradiation produces such a minimal chemical change in food that it is difficult to design a test to determine whether a food has been irradiated (44).

A small number of new compounds are formed when food is irradiated, just as new compounds are formed when food is exposed to heat in other processing or cooking methods. Early research described these new compounds as "unique radiolytic products" because they were identified after food was irradiated (9). Subsequent investigations have determined that free radicals and other compounds produced during irradiation are identical to those formed during cooking, steaming, roasting, pasteurization, freezing, canning, and other forms of food preparation (9,11,13,22,29). Free radicals are even produced during the natural ripening of fruits and vegetables (43). All reliable scientific evidence based on animal feeding tests and consumption by human volunteers indicates these products pose no unique risk to human beings. In fact, people requiring the safest food--hospital patients receiving bone marrow transplants--are often served irradiated and/or pasteurized foods. Furthermore, because spices, being of tropical origin, are often microbe-laden, irradiated spices are preferred for routine use in hospital foodservice for patients. As with pasteurization, evidence suggests that food irradiation can make better a quality food supply.

AMA's Report of the Council on Scientific Affairs on Food Irradiation (11) agreed with a FAO/WHO policy statement (4,45) released in 1992. Irradiated food produced under established good manufacturing practices is to be considered safe and nutritionally adequate because:

i) the process of irradiation will not introduce changes in the composition of the food which, from a toxicological point of view, would impose an adverse effect on human health; ii) the process of irradiation will not introduce changes in the microflora of the food which would increase the microbiological risk to the consumer; iii) the process of irradiation will not introduce nutrient losses in the composition of the food, which, from a nutritional point of view, would impose an adverse effect on the nutritional status of individuals or populations (11, p 1).

In a 1999 report, the WHO and allied organizations concluded on the basis of knowledge derived from over 50 years of research that irradiated foods are safe and wholesome at any radiation dose (46). The limitation at very high doses is palatability, not food safety.

Environmental Safety of Food Irradiation

Strict regulations govern the transportation and handling of radioactive material. Irradiation facilities using radioactive material are constructed to withstand earthquakes and other natural disasters without endangering the community or workers. Radioactive material is transported in canisters tested to withstand collisions, fires, and pressure. Worker safety is protected by a multifaceted protection system within the plant (12). USDA-proposed regulations mandate that workers be trained in the safe operation of irradiation equipment (47). Establishments choosing to irradiate meat or meat products will be required to comply not only with USDA Food Safety and Inspection Service (FSIS) and FDA requirements regarding the safety of irradiated products, but also with the Nuclear Regulatory Commission, Environmental Protection Agency, Occupational and Safety Health Administration, Department of Transportation, and state and local government requirements regulating the operation of irradiation facilities. These regulations include maintenance of appropriate environmental, worker safety, and public health protection (47).

The 60Co used by US commercial facilities is specifically produced for use in irradiation of medical supplies and other materials. It is not a waste product of any other activity, and it cannot be used to make nuclear weapons. All the spent 60Co to date--in such a small amount--could fit in an office desk (9,10). Disposal of 60Co is carefully arranged by the producer. Electron beam radiators are operated by electricity and use no radioactive isotopes.

Regulation of Food Irradiation

Congress defined the sources of ionizing energy as food additives and included them in the Food Additives Amendment to the Federal Food, Drug, and Cosmetic Act of 1958 (48,49), thus delegating the main regulatory responsibility to the FDA. Additionally, 2 agencies within the USDA are involved in the process: the FSIS, which develops standards for the safe use of irradiation on meat and poultry products, and the Animal and Plant Health Inspection Service, which monitors programs that are designed to enhance animal and plant health (eg, using irradiation as an insect quarantine treatment in fresh produce) (48). Before December 1999, coordination between USDA and FDA for writing the rules lengthened the time for irradiated meat and meat products to be available in the marketplace. For example, FDA approved red meat in December 1997, but it was not until December 1999 that the joint process of writing the rules was completed (50). In the future, a streamlined approval process for food additives that does not require separate approval of both FDA and USDA for meat and poultry products will be used (51). This process is expected to pave the way for irradiation of processed meat and poultry products for which the petition was submitted in August 1999 (47).

All irradiated foods sold at the retail level in the United States must be labeled with a Radura, an international symbol for irradiation (Figure 5), and the words "treated by irradiation" or "treated with radiation." Products that contain irradiated ingredients, including spices, are not required to be labeled as such. The ADA supports the present labeling rules, including use of the Radura and current wording on irradiated foods. The ADA also supports incentive labeling in which a specific pathogen is listed on the label as being reduced, such as "treated by irradiation to reduce Salmonella and other pathogens" (52). However, the ADA is concerned about statements that imply the irradiated food is free of pathogens, such as "free of Salmonella," because food irradiation does not prevent recontamination of the irradiated food (53). Incentive labeling as specified by USDA regulations stipulates that elimination of a pathogen must be scientifically documented (50). A continuing area of research is identification of scientific detection methods to verify that unlabeled foods have not been irradiated and that foods have received the intended dose (49). An international general standard covering irradiated foods was adopted by the Codex Alimentarius Commission, a joint body of WHO and FAO. The standards are based on the findings of the Joint Expert Committee on Food Irradiation convened by FAO, WHO, and the International Atomic Energy Agency (11).

Food categories currently approved for irradiation in the United States are listed in Figure 4. In 1999, the operating US irradiation facilities process spices, citrus fruits, tropical fruits, strawberries, tomatoes, mushrooms, potatoes, onions, and poultry.

Any new application of irradiation must undergo food additive approval. A petition is being developed to permit irradiation of cooked, ready-to-eat meat, with control of Listeria being the principal benefit. FDA response to petitions for shellfish, shell eggs, and a range of additional ready-to-eat foods is expected. The opportunity to control Salmonellae and E coli in bean sprouts is particularly important as these foods, along with many fruits and vegetables, are not usually cooked before consumption. The ADA supports continued expansion of categories to include such products as fish, shellfish, eggs, produce, ready-to-eat products, and mixed foods (53).

Consumer/Producer Issues

Despite repeated endorsements and regulatory approval, irradiated foods are not widely available in the United States. Although consumers are familiar with food irradiation, many have little knowledge of the process and its advantages (54). When consumers receive science-based information on food irradiation, however, most prefer irradiated to nonirradiated spices, poultry, pork, beef, and seafood (25). Concern about foodborne illness has increased consumer interest in irradiated food. A nationwide survey conducted in March 1998 found that almost 80% of the population sample said they would buy products labeled "irradiated to destroy harmful bacteria" (55). Sixty-seven percent of consumers said it was "appropriate" to irradiate poultry; slightly fewer consumers deemed it "appropriate" to irradiate pork and ground beef. More than 60% thought irradiation was appropriate at a fast-food restaurant, and almost 50% considering it appropriate at the grocery store delicatessen or sit-down restaurant.

In another nationwide survey, consumers indicated they would pay a premium for irradiated ground beef (54). The increase in cost for irradiated foods is estimated at $0.02 to $0.03 cents per pound for fruits and vegetables and $0.03 to $0.08 cents per pound for meat products (16,17,56). Produce has been marketed without a price premium as a result of decreased losses and increased shelf life. Part of the cost for meat and poultry irradiation relates to packaging material. Currently only a limited number of materials are available and special, more expensive meat trays must be used. It has been estimated that the savings from the reduction of foodborne illness are substantially greater than the modest increase in food cost (14,47).

Consumer performance in the marketplace supports the results of attitudinal surveys (27). Mangoes labeled as irradiated sold successfully in Florida in 1986. In March 1987, irradiated Hawaiian papayas, available in a 1-day trial in Southern California, outsold the identically priced nonirradiated counterpart by greater than 10 to 1. Irradiated apples marketed in Missouri were also favorably received. Record amounts of irradiated strawberries were sold in Florida in 1992 and irradiated strawberries, grapefruit, juice oranges, and other products continue to outsell their nonirradiated counterparts in a specialty produce store in Chicago, Ill. Irradiated poultry, which is available in select markets, has experienced brisk sales (27). A University of Georgia shopping simulation test (57) showed a significant increase in the proportion of consumers purchasing irradiated ground beef after they participated in an educational program on the benefits of food irradiation. After receiving information, 71% purchased irradiated beef, including 62% of the consumers who originally stated they would not purchase irradiated food. Consumers in Kansas have purchased labeled irradiated poultry in market tests in 1995 and 1996. The irradiated poultry captured 63% of the market share when priced 10% less than store brand, and 47% when priced equally. In 1997, after reading a brief description of irradiation, 80% of consumers selected irradiated poultry when it was priced the same as the nonirradiated house brand (58). According to G. Dietz of Isomedics in Whippany, NJ (oral communication, March 2, 1998), in 1998, more than 20,000 lb irradiated fruits from Hawaii--including papaya, atemoya, rambutan, lychee, and starfruit--have sold in Midwest and California markets.

Consumers indicate that information about irradiation should include a discussion of the safety and benefits of the process and the effect on nutritional value (28,55). An endorsement by health professionals is desirable. Consumers prefer to receive information in newspapers and government flyers.

The Role of Dietetics and Other Health Professionals

ADA and qualified dietetics professionals have the responsibility to educate consumers about food and nutrition issues, including technologies such as food irradiation. As advocates for the public on food and nutrition issues, dietetics professionals are in a unique position to monitor the advancement and further implementation of food irradiation technology. A working knowledge of food technologies is expected of students in entry-level dietetics education programs. Dietetics professionals should be advocates for the availability of irradiated foods in the marketplace, especially for consumers considered at high risk for infectious disease and, thus, particularly susceptible to foodborne pathogens. This includes individuals across the lifespan from the very young (infants and children in day care) to older Americans with stressed immune systems. Pregnant women and their fetuses would benefit from food irradiation because of their specific risk for Listeria monocytogenes. Additionally, clients of all ages with immune-suppressing diseases (such as human immunodeficiency virus) and those undergoing immune-suppressing therapies (eg, chemotherapy) would benefit from food free of harmful bacteria. Dietetics professionals who manage large-scale foodservice operations can use irradiated foods in the implementation of a Hazard Analysis and Critical Control Point (HACCP) system. A generic model developed by the International Meat and Poultry HACCP Alliance is available from the FSIS (59) or on the World Wide Web from Texas A&M University.

At the present time, expanded education for the public and food retailers about food irradiation is needed. Educational programs, in which health professionals work with food industry representatives to present accurate information about irradiation to the public, should be offered. Educational materials about food irradiation are available from a variety of resources including colleges and universities, the FDA, public health agencies, and marketing agencies (19). See Figure 6 for additional resources. A current and validated educational packet (28) including a consumer audiovisual is available through the Agricultural Communication Service, Purdue University, West Lafayette, Ind.

Although the safety and efficacy of irradiation are well established, continued research on the ability of irradiation to destroy new and emerging microbial pathogens is appropriate. With today's demand for high-quality convenience foods, researchers should evaluate the effectiveness of irradiation in combination with other processing methods to enhance the safety of minimally processed foods or extend the quality and shelf life of fresh-cut produce.

In an era of increasing concern about food safety, consumers must understand that irradiation is a method to enhance food safety. Health professionals can help allay the fears of consumers and food industry workers through education.


ADA members and dietetics professionals at the local level can assist the Association in promoting the value of irradiated foods by providing consumer education on this issue. This could be accomplished through writing articles for local newspapers, participating in interviews with the media, or using irradiated foods as a topic for consumer-specific educational or community programs. The position can also be used to respond to debates about the use of food irradiation. Also, consider collaborating with local grocery stores to provide educational materials for consumers that address the various issues of food irradiation and food safety.


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29. Olson DG. Scientific Status Summary, Irradiation of Food. A Publication of the IFT Expert Panel on Food Safety and Irradiation. Food Technol. 1998:52(1):56-62.
30. Murano P, Murano E, Olson D. Irradiated ground beef: Sensory and quality changes during storage under various packaging conditions. J Food Sci. 1998; 63:548-551.
31. Ahn DU, Olson DG, Lee JI, Jo C, Wu C, Chen X. Packaging and irradiation effects on lipid oxidation and volatiles in pork patties. J Food Sci. 1998;63:15-19.
32. Ahn DU, Olson DG, Jo C, Chen X, Wu C, Lee JI. Effect of muscle type, packaging, and irradiation on lipid oxidation, volatile production, and color in raw pork patties. Meat Sci. 1998;49:27-39.
33. Abu-Tarboush HM, Al-Kahtani HA, Atia M, Abou-Arab AA, Bajaber AS, El-Mojaddidi MA. Sensory and microbial quality of chicken as affected by irradiation and postirradiation storage at 4.0°C. J Food Protect. 1997; 60:761-770.
34. Thayer DW. Use of irradiation to kill enteric pathogens on meat and poultry. J Food Safety. 1995;15:181-192.
35. Thayer DW, Josepson ES, Brynjolfsson A, Giddings GG. Radiation Pasteurization of Food. Ames, Iowa: Council for Agricultural Science and Technology; 1996. Issue paper no. 7.
36. Dubey JP, Thayer DW, Speer CA, Shen SK. Effect of gamma irradiation on unsporulated and sporulated Toxoplasma gondii oocycts. Int J Parasitology. 1998;28:1-6.
37. Osterholm MT, Potter ME. Irradiation pasteurization of solid foods: taking food safety to the next level. Emerg Infectious Dis. 1997;3(4):1-3.
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ADA Position adopted by the House of Delegates on October 29, 1995, and reaffirmed on September 28, 1998. This position will be in effect until December 31, 2003. ADA authorizes the republication of the position, in its entirety, provided full and proper credit is given. Requests to use portions of this position must be directed to ADA Headquarters at 800/877-1600, ext. 4896, or ppapers@eatright.org.

Recognition is given to the following for their contributions:

Olivia Bennett Wood, MPH, RD (Purdue University, West Lafayette, Ind) and Christine M. Bruhn, PhD (University of California-Davis)

ADA Government Relations Team (Tracy Fox, MPH, RD); Alfred A. Bushway, PhD (University of Maine, Orono); Mildred Cody, PhD, RD (Georgia State University, Atlanta); Management in Food and Nutrition Systems dietetic practice group (Jill Irvin, MA, RD); Public Health Nutrition dietetic practice group (Pamela Van Zyl York, PhD, MPH, RD); Sue Snider, PhD, RD (University of Delaware, Newark); Catherine Hemphill Strohbehn, PhD, RD (Iowa State University, Ames).

Members of the Association Positions Committee work group:
Kathleen Emmert, MSA, RD; Valerie Duffy, PhD, RD; Robert Earl, MPH, RD.

Food Irradiation Can Enhance Safety of Nation's Food Supply

January 9, 1996 ADA Press Release

The American Dietetic Association (ADA) said today that food irradiation is one way to enhance the safety and quality of the food supply in the United States. Estimates place the number of cases of foodborne illnesses that occur domestically between 6.5 to 33 million; about 9,000 of these resulting in death.

ADA acknowledges that many consumers are not familiar with food irradiation or the dangers of foodborne illnesses from pathogens, mishandling and improper cooking techniques. In it's most recent position, published in the January issue of The Journal of the American Dietetic Association, the association encourages the government, food manufacturers, food commodity groups and dietetics professionals to continue working together to educate consumers about this technology and food safety.

Despite repeated endorsements and regulatory approval, irradiated foods are not widely available in the United States. Worldwide, 38 countries permit food irradiation, and in Europe more than 28 billion pounds of food is irradiated annually.

ADA cautions that food irradiation does not replace proper food handling.

And, the association concludes that irradiation cannot enhance the quality of food that is not fresh, or prevent contamination that occurs after irradiation during storage or preparation.

With more than 66,500 members, the Chicago-based American Dietetic Association is the world's largest organization of food and nutrition professionals. ADA serves the public by promoting optimal nutrition, health and well-being.

The Journal of the American Dietetic Association is the most widely-read, peer-reviewed periodical in the dietetics field. Published monthly, it brings original research, critical reviews and reports, authoritative information and expert commentary to nutrition and dietetics professionals throughout the world.

Figure 1

Definitions related to food irradiation.

Cold pasteurization or electronic pasteurization Irradiation at pasteurizing doses. Industry must demonstrate that all vegetative pathogens are destroyed.

Gray The SI unit of measurement of absorbed radiation. One joule of energy is absorbed per kilogram of matter being irradiated. 1,000 Grays (Gy)=1 kiloGray (1 kGy).

Ionizing radiation Radiation capable of converting atoms and molecules to ions by removing electrons.

Irradiation Treatment with radiation or treated by irradiation.

Irradiation dose The amount of kiloGray used to irradiate a product.

Irradiator The part of a radiation facility that houses the source of irradiation.

RAD Term formerly used to measure radiation. 100 rad=1 Gy.

Radiation Ionizing radiation.

Radiolytic product A substance produced from irradiation.


Figure 2
Diagram of Cobalt Irradiator

Figure 2 - Diagram of a cobalt-60 irradiator.
Courtesy of Atomic Energy of Canada, Ltd., Ottawa, Canada

Figure 3
Diagram of an electron beam irradiator.
Courtesy of TITAN SCAN Corp SUREBEAM® Technology, Sioux City, Iowa


Figure 3 - Diagram of an electron beam irradiator.
Courtesy of TITAN SCAN Corp SUREBEAM® Technology, Sioux City, Iowa


Figure 4
Food irradiation rules from the US Food and Drug Administration


Purpose of irradiation

Dose permitted (kGy)a

Date of rule

Wheat and wheat powder

Disinfest insects


August 21, 1963

White potatoes

Extend shelf life


November 1, 1965

Spices and dry vegetable seasoning

Decontamination/disinfest insects

30 (maximum)

July 15, 1983

Dry or dehydrated enzyme preparations

Control insects and microorganisms

10 (maximum)

June 10, 1985

Pork carcasses or fresh non-cut processed cuts

Control Trichinella spiralis

0.3 (minimum)- 1.0 (maximum)

July 22, 1985

Fresh fruits

Delay maturation


April 18, 1986

Dry or dehydrated enzyme preparations



April 18, 1986

Dry or dehydrated aromatic vegetable substances



April 18, 1986


Control illness-causing microorganisms


May 2, 1990b

Red meat

Control illness-causing microorganisms

4.5 minimum (refrigerated)- 7 maximum (frozen)

December 3, 1997b

aSource: References 5 and 47
bUSDA food processor guidelines completed for poultry September 1992; for red meat December 1999

Figure 5
Radura Symbol

Figure 4 - Radura symbol

FIG 6. Resources for educational material on food irradiation.

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