So this is the process--no thanks---------------------------------he Food Irradiation Process
Irradiation exposes food to radiant energy. (See Figure 1 for definitions of food
irradiation terminology.) Food is passed through an enclosed chamber - an
irradiator - where it is exposed to an ionizing energy source (Figure 2). Although
the sources of ionizing energy may be gamma rays from cobalt 60 (60Co) or cesium
137 (137Cs), x-rays, or electrons generated from machine sources (7,8), food
irradiation in the United States relies exclusively on the use of (60Co) (9,10), which is
contained in stainless-steel rods placed in racks. The gamma rays emitted 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), "meltdown" and chain reactions cannot occur, and
irradiated foods and their packaging are not made radioactive (8,10-12). The (60Co)
gamma 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 gamma energy, density of food, and amount of energy
emitted by the irradiator determine the amount or dose of irradiation to which the
food is exposed (8,10,11,13). Regulated doses are set at the minimum levels
necessary to achieve specified purposes or benefits (Figure 3). Radiation doses
allowed by the US Food and Drug Administration (FDA) are the most restrictive of
all countries in which irradiation is allowed (10). 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 poultry, and high doses (above 10 kGy)
control microorganisms in herbs, spices, teas, and other dried vegetable substances
(14).
Food irradiation does not replace proper food handling. The lower doses of
irradiation permit microorganisms to survive (8). 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 during storage or preparation.
Historical Summary of Food Irradiation
Food irradiation has the longest history, more than 40 years, of scientific research
and testing of any food technology before approval (10). Research has been
comprehensive, and has included wholesomeness, toxicological, and
microbiological evaluation. In 1955, the Army Medical Department began to assess
the safety of types of foods commonly irradiated in the US diet (15). Petitions to the
FDA for approval of specific foods for irradiation soon followed - wheat and wheat
powder received the first approval in 1963 (Figure 3). 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 continues today (16).
The first products approved by the FDA were wheat and white potatoes in the
1960s. During the 1980s, FDA approved petitions for irradiation of spices and
seasonings, pork, fresh fruits, and dry or dehydrated substances. Poultry received
approval in 1990. Currently, petitions for seafood, ground beef, and eggs are pending
approval. Worldwide, 38 countries permit irradiation of food, and more than 28
billion lb of food is irradiated annually in Europe (6,17). The United States has 40
licensed irradiation facilities; most are used to sterilize medical and pharmaceutical
supplies, but 16 also irradiate spices for wholesale use, and several others irradiate
food. Food irradiation has an impressive list of national and international
endorsements: ADA, American Council on Science and Health, American 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
the World Health Organization (WHO).
Benefits of Food Irradiation
Treating foods with gamma rays offers benefits to consumers, retailers, and food
manufacturers such as improved microbiological quality, replacement of chemical
treatments, and extended shelf life. The benefits depend on the treatment used
(Figure 2). The microbial count in spices can be lowered through irradiation, and the
process substitutes for use of the fumigant ethylene oxide. Compared with other
quarantine treatments, irradiation results in a higher-quality fruit. Pathogens in raw
poultry or meat can be reduced by 99.9% by a low "pasteurization" dose of radiation
(13). Use of still lower doses can disinfest grain and produce and can retard natural
senescence of fruit and vegetables. This all results in the reduced use or elimination
of chemical treatments. Irradiated foods closely resemble foods in their fresh state
(8,12).
Effect of Irradiation on Nutritive Value of Food
Irradiation has been compared with pasteurization because it destroys pathogenic
bacteria. Because irradiation does not substantially raise the temperature of the food
being processed, nutrient losses are small and are often substantially less than
nutrient losses associated with other methods of preservation, such as canning,
drying, and heat pasteurization and sterilization (7,8,10,11). The relative sensitivity
of 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 (8).
Proteins, fats, and carbohydrate are not notably altered by irradiation (7,8,12). In
general, those nutrients most sensitive to heat treatment, such as the B vitamins and
ascorbic acid, are those most sensitive to irradiation. Diehl (8) and Thorne (12)
compared nutrient 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 (8). Nutrient losses can be further
minimized by irradiating food in an oxygen-free environment or in a frozen state
(8,12). Fox and coworkers (18) derived a formula to calculate predicted losses in
cooked pork and chicken on the basis of data on quantities of these items from the
second National Health and Nutrition Examination Survey in the US diet and
irradiation doses allowed by FDA. Predicted losses for thiamin, riboflavin, and niacin
in pork and thiamin in chicken ranged from 0.01% to 1.5%. Earlier reports regarding
losses of ascorbic acid in potatoes, due to a shift to dehydroascorbic acid, are no
longer considered valid as they failed to consider that dehydroascorbic acid also has
vitamin activity (8). In a study of the ascorbic acid content of oranges, Nagai and
Moy (19) found no significant differences between irradiated and control fruit at
dose levels up to 1.0 kGy and throughout a 6-week storage period.
Sensory qualities such as appearance and flavor have been evaluated in the
laboratory (8,17,19,20) and in market studies with consumers (15,20). Consumers
consistently rate irradiated fruit as equal or better than nonirradiated fruits in
appearance, freshness, and taste (15,20,21).
Food Safety
Irradiation does cause 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). Additionally, human volunteers
consuming up to 100% of their diets as irradiated food have shown no ill effect (8).
Irradiation produces so little chemical change in food that it is difficult to design a
test to determine whether a food has been irradiated (23).
A small number of new compounds are formed when food is irradiated, just as new
compounds are formed when food is exposed to heat. Early research described
these new compounds as "unique radiolytic products" because they were identified
after food was irradiated (8). Subsequent investigations have determined that free
radicals and other compounds produced during irradiation are identical to those
formed during cooking, steaming, roasting, pasteurization, freezing, and other forms
of food preparation (8,10,12). Free radicals are even produced during the natural
ripening of fruits and vegetables (22). All reliable scientific evidence, based on
animal feeding tests and consumption by human volunteers, indicates that these
products pose no unique risk to human beings. In fact, people requiring the safest
food, hospital patients receiving bone marrow transplants, are routinely given
irradiated foods. Furthermore, because spices, being of tropical origin, are often
microbe laden, irradiated spices are preferred for routine use in hospital foodservice
for patients. Thus, as with pasteurization, the evidence suggests that food irradiation
can make a quality food supply better.
The American Medical Association's Report of the Council on Scientific Affairs on
Food Irradiation (10) agreed with a WHO policy statement (4,24) 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 (10)."
Environmental Safety of Food Irradiation
Strict regulations govern the transportation and handling of radioactive material.
Irradiation facilities 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 (11).
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. It is estimated that all
the spent 60Co to date could fit in an office desk (8,9). Disposal of 60Co is carefully
arranged by the producer.
US 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
(25), thus delegating the main regulatory responsibility to the FDA. Additionally, two
agencies within the US Department of Agriculture (USDA) are involved in the
process: the Food Safety and Inspection Service, 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 designed to enhance animal
and plant health (eg, using irradiation as an insect quarantine treatment in fresh
produce) (25).
All irradiated foods in the United States must be labeled with a radura, the
international symbol for irradiation (Figure 4),and the words "treated by irradiation"
or "treated with radiation." Products that contain irradiated ingredients, such as
spices, are not required to be labeled. A continuing area of research is identifying
scientific detection methods to verify that unlabeled foods have not been irradiated
and that labeled foods have received the intended dose (23). An international
general standard for irradiated foods and facilities was adopted by the Codex
Alimentarius Commission, a joint body of the WHO and the FAO. The standards are
based on the findings of the Joint Expert Committee on Food Irradiation convened
by the FAO, WHO, and International Atomic Energy Agency (10).
Food categories currently approved for irradiation in the United States are listed in
Figure 3. The US facilities currently in operation process spices, citrus fruits, tropical
fruits, strawberries, tomatoes, mushrooms, potatoes, onions, and poultry.
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 (26).
When consumers receive science-based information on food irradiation, however,
most prefer irradiated to nonirradiated spices, poultry, pork, beef, and seafood (20).
In a nationwide survey, consumers indicated that they would pay a premium for
irradiated ground beef (26). The increase in cost for irradiated foods is estimated at
2 to 3 cents per pound for fruits and vegetables and 3 to 5 cents per pound for meat
products (15,16). Produce has been marketed in some locations without a price
premium due to decreased losses and increased shelf life. It has been estimated that
the savings from the reduction of foodborne illness are substantially greater than the
modest increase in food cost (13).
Marketing studies support the results of attitudinal surveys (20). Mangoes labeled
as irradiated sold successfully in Florida in 1986. In March 1987, irradiated
Hawaiian papayas, available on a 1-day trial in Southern California, outsold the
identically priced nonirradiated counterpart by greater than ten to one. 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. A University of Georgia
shopping simulation test (27) 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 those consumers who originally
said they would not purchase irradiated food.
Role of Dietetics and Health Professionals
ADA and qualified dietetics professionals have the responsibility to educate
consumers about food and nutrition issues, including new technologies such as food
irradiation. As advocates for the public on food and nutrition issues, dietitians are in
a unique position to monitor the advancement and further implementation of food
irradiation technology.
The greatest need is expanded education for the public and for food retailers. Pilot
educational programs could be offered in which health professionals work with food
industry representatives to present accurate information about irradiation to the
public. Educational materials about food irradiation are available from a variety of
resources including colleges and universities and the FDA. A current and validated
educational packet (21), which includes 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 one method of enhancing an already safe food supply. Health
professionals can assist in consumer and food industry education.---------------I also understand I may grow another head on my shoulder after eating food with this s*** on it after 10 years!!! |
