Contaminated foods are one of the most widespread health problems in the world and are a major contributing factor to reduced economic productivity in developing countries. The illnesses contracted from contaminated food are generally caused by microorganisms such as bacteria, viruses, molds, and parasites and usually result in conditions such as diarrhea, gastrointestinal pain and discomfort, vomiting, and headache. In the most serious cases, they can result in death.
Food irradiation is a safe and cost-effective way of eliminating contaminants in foods. Although some developing countries are using this technology, misunderstandings about the risks and benefits of irradiation are preventing it from being used as widely as it should be in efforts to provide a safe food supply in the developing world.
The magnitude of food-borne disease episodes is such that few countries have the ability to monitor their incidence. The Centers for Disease Control and Prevention in Atlanta estimates that the number of cases of food-borne diseases in the United States is now about 30 percent of the population per year; the rate of food poisoning in developing countries is likely to be considerably higher. The food-borne diseases prevalent in developing countries include cholera, typhoid, salmonellosis, campylobacteriosis, shigellosis, amoebiasis, and E. coli infections. Although the full magnitude of the problem has yet to be accurately quantified, the available statistics show an alarming upward trend.
The major cause of illness and death in infants and children in developing countries is diarrheal disease. Children under the age of five suffer two to three major episodes of diarrhea per year, and almost 70 percent of these episodes result from contaminated food. Chronic aftereffects reduce the nutritional status and compromise the immune systems of these children. The stark statistic is that more than 2 million children under the age of five die each year from ingestion of contaminated food.
The recent globalization of the world’s food supply has the potential to contribute to the proliferation of food-borne disease. Food-borne disease organisms move together with traded goods, crossing international borders with impunity. Since these organisms travel with the tiniest particles of dust carried in the wind and are easily swept along international waterways, even the most rigorous quarantine procedures cannot prevent their movement between countries.
In addition to their effects on overall health, the economic and social consequences of food-borne diseases are extremely serious. When factors such as lost labor or income, medical or hospitalization expenses, and other associated costs are taken into account, the estimates run into billions of dollars. The cost of salmonellosis alone was conservatively estimated at more than US$1 billion in 1987 in the United States. Such estimates are only the tip of the iceberg. The value of lost opportunities, ruined futures, and grief due to illness and death are impossible to calculate.
Ensuring the safety of foods requires preventing contamination, which is not as easy as it sounds. Almost all basic food materials originate from an open or exposed environment. Grain, legumes, fruits, vegetables, meat and dairy animals, poultry, and seafood are all produced and harvested in a fully exposed environment or in production complexes that are generally open to the ambient surroundings. As a result they are exposed to all the organisms, harmful and otherwise, that naturally exist in the environment.
Despite efforts to exercise good agricultural practices, raw foodstuffs may still become contaminated with pathogenic organisms, particularly in countries where food animals are not maintained in sanitary conditions and where untreated waste and wastewater is used for fertilization and irrigation. The warm, humid environment of many developing countries is ideal for the growth and proliferation of pathogenic organisms. The poor methods used to handle foods down the food distribution chain further contribute to an increase in contamination.
Food irradiation is a physical process that exposes foods to a highly penetrating form of energy—gamma rays or high-energy electrons. Gamma rays and high-energy electrons can uniformly inactivate the DNA of unwanted microorganisms without changing the basic nature of the treated food. Fresh irradiated foods are virtually indistinguishable from fresh untreated foods, except for the label and in many cases an improved appearance. The gamma rays and electrons used in the process are simply energy, just as heat, light, or microwaves are—they are not particles and therefore leave no residues. Food irradiation does not make foods radioactive.
While some people fear that food irradiation might allow manufacturers to dispense with good manufacturing practices, the contrary is true. Foods destined for further processing require greater attention to quality maintenance throughout the process to ensure that the subsequent value-addition will be realized. The more steps in the process, the greater the possibility for product rejection anywhere along the route. The same fears were originally voiced over the use of pasteurization, yet after almost a century of use, the on-farm quality of milk is higher than ever.
The choice of which irradiation system to employ depends largely on the type of product to be processed, the expected cost, and public concerns. Cobalt-based gamma irradiators have much greater penetration than electron-beam irradiators and are the choice for larger products or pallets. Because cobalt emits gamma rays continually, it has a limited half-life and must be replaced regularly, whether or not it is being used to irradiate foods. Cobalt-based irradiators are therefore most cost-efficient when they are used to irradiate a constant stream of food products on a 24-hour basis.
Electron-beam machines can only penetrate fairly restricted depths (10 centimeters), so they are suited to products that can be conveyed in layers of limited thickness. They can, however, be switched on at will, so they are not as sensitive to throughput considerations as are cobalt irradiators.
Public concern over potential environmental problems is another important issue. Because cobalt is not water soluble, the actual environmental risks associated with operating gamma irradiators are infinitesimally small and the irradiators have an outstanding safety record. Because electron-beam irradiators can be turned on and off like a light bulb, they are currently more acceptable to most communities. In the future, x-ray irradiators will combine the advantages of high penetration and on-off switching.
Food irradiation is a safe process that has been approved by all the international and national health authorities and medical associations and is highly recommended by public health officials all over the world. Purchasing irradiated foods is listed as one of World Health Organization’s 10 Golden Rules of Food Safety. It can be used on most fruits and vegetables, meat, poultry, fish, seafood, spices, potatoes, grains, and a host of other commodities. Currently, it is used on spices, certain fruits and vegetables, poultry, and beef in the United States.
Irradiation facilities are not complex and exist in many developing countries throughout Asia and Latin America. As long as there is an infrastructure capable of keeping a plant supplied with sufficient raw materials and services, the operation of irradiation facilities is likely to be financially viable. Depending on the food product and treatment in question, the cost of food irradiation varies between 2 and 6 cents per kilogram—a low price considering the hygienic and health benefits it provides.
If food irradiation holds such benefits for the consumer, why is it not used more commonly? Semantics has played a major role in the public confusion surrounding the subject of food irradiation. Ever since the first atomic bomb was dropped, we have had a great fear of the word “radiation.” The accidents at Three Mile Island and Chernobyl have only heightened this fear.
But while misguided fear may have had some influence with the public in the past, the endorsement of food irradiation by all medical and public health authorities has had an even greater impact. All of the most recent studies carried out by universities and national polling organizations show that current consumer fears of food-borne diseases far exceed any lingering fears of food irradiation. Consumers will purchase irradiated foods, particularly when they are made aware of the improved hygienic quality of the food. The basic lesson is simple—consumers are unlikely to accept any new technology unless they understand the personal advantages it holds.
Food-borne diseases are a serious problem the world over. Strategies to control them that are based on political ideals or “myth-information” will not be effective. To the extent that centralized processing can be carried out on hazardous commodities, food irradiation should be promoted actively wherever possible. Getting rid of pathogens requires killing them before they kill people, and food irradiation is one of the safest and most effective ways to do this.
For further information see M. Satin, Food Irradiation and Food Irradiation, 2d ed. (Lancaster, Pa., USA: Technomic Publishing, 1996); M. Satin, Food Alert! The Ultimate Sourcebook for Food Safety (New York: Facts on File, 1999); and M. Satin, La Irradiacion de los Alimentos (Zaragoza, Spain: Acribia, 2000).
Morton Satin (Morton.Satin@fao.org) is chief of the Agricultural Industries and Post-Harvest Management Service of the Food and Agriculture Organization of the United Nations. In January 2002 he will assume the post of executive director of the International Food and Agribusiness Management Association, housed at Texas A&M University.