Consumers Essay, Research Paper
Using Irradiation to Make Food Safer for Consumers
In the world today, there is a limited access to fresh and uncontaminated food. Gunjan Sihna, of Popular Science, reports that “The U. S. Centers of Disease Control estimates 6.5 million confirmed cases and more than 25 million additional unreported incidents of food poisoning each year” (65). For example, with seventy-five percent of the chicken in Europe and sixty percent of the chicken in the United States infected, salmonella is a serious problem (”Food Irradiation”). The United States reports about two million cases of salmonella per year, costing an estimated 2.44 billion dollars. “All creatures carry thousands of different bacteria in their bodies, yet most of these microbes are harmless or even beneficial,” says Sinha (65). Unfortunately, there are still many bacteria that cause problems for humans. For example, E. coli is usually found in the gut of cows. Although most people do not eat this part of the cow, the beef may sometimes be cross-contaminated if the intestines are accidentally split during slaughter. Steps are needed to minimize the risk of food contamination on the world’s population. Irradiation should be used to kill pathogens and extend the shelf life of food.
After decades of exhaustive studies, experts agree that irradiation is safe and effective against food-borne pathogens. When irradiation is mentioned, many people think of nuclear radiation and then of Hiroshima and Nagasaki, or of Three Mile Island. “Do you want your food nuked?” inquire the opponents of irradiation (Satin 1-2). “Irradiation can be portrayed by anti-nuclear (sic) fanatics as something only welcome if you like chickens that come with three drumsticks, or turkey tetrazzini that glows in the dark,” says Stephen Chapman of the Chicago Tribune (3). The proponents of irradiation blame this fear on nothing more than the name, which has lead to the common misconception and association with nuclear radioactivity. Irradiation is correctly called “ionizing” in France, to avoid association with the negative meaning of the root word, radiation (Satin 3). This is not twisting it around, but simply giving another name to the same process.
Irradiation is simply the process of exposing food or some other substance to low levels of radiation. Irradiation does not make food radioactive, and it does not make it glow. In fact, every time one goes outside, one is being irradiated by the sun. If sun lotion was called “radiation protection cream or irradiation lotion,” people would be turned off at first (Satin 4). People would eventually realize that there was nothing to fear and would use it.
Radiation is thought by most people only to be present in nuclear bombs and power plants. Radiation, from Webster’s New Collegiate Dictionary, is the process of emitting radiant energy in the form of waves or particles (”radiation”). This includes all energy in the electromagnetic spectrum. Light rays, radio waves, microwaves, and heat are all forms of radiation, and we do not fear them. In fact, microwave ovens use radiation and are present in almost every American household. They were at one time feared, as irradiation is now. People eventually began to accept them for their efficiency and convenience.
Irradiation works to disable cells by making changes to their DNA or RNA (nucleic acids). The gamma radiation used in irradiation makes changes to these highly complex macromolecules. The change is just enough to render them inoperable. Irradiation kills food pathogens, insects, and other pests. Complete sterilization can also be achieved by the use of irradiation. Salmonella, listeria, and campylobacter can be killed or greatly reduced (”Food Irradiation”). Irradiation can delay ripening and spoilage of produce. For example, potatoes often ripen in storage, due to the change of starches into glucose, and become mushy. Irradiation disables the macromolecules responsible for this change. Precooking the potatoes has the same effect but is not practical (Satin 13).
One of the concerns about irradiation is the formation of free radicals. These free radicals, or electrically charged particles, are formed during the process of irradiation. Free radicals are slightly unstable and try to find another compatible free radical to link to, forming a stable radiolytic compound. This happens faster in moist than in dry foods. This is because the free radicals are more free to move in liquids than in solids. These radiolytic compounds and free radicals may sound scary to many people when they are taken out of context. However, these compounds are very common, and they are formed during everyday events such as metabolism and other simple biochemical reactions (Satin 18).
Gamma radiation can be used to irradiate food. This requires an unstable isotope which slowly decays and emits gamma radiation. One such isotope is Uranium-238. Although it is not used in irradiation, it is commonly used as an example to show how gamma radiation is emitted. Uranium-238 is very unstable and can hardly hold itself together. Eventually, a particle made of protons and neutrons breaks free from the atom forming a new atom, thorium-234. The process continues, changing into protactinium-234, and eventually into lead-206. Occasionally during the remainder of the decay, non-particle radiation is released in the form of gamma (y) radiation. Gamma radiation is the form of nuclear radiation that is used in food irradiation.
Gamma rays (as previously mentioned) are used in one type of irradition plant, the gamma ray type facilities. The most common radioactive substance used in this process is cobalt-60, but cesium-137 is also used. Pellets of the cobalt-60 are stored in stainless steel cylinders called pencils. Each pencil is about 17.75 inches long and one half inch in diameter (Murano 11-12). The pencils are transported to the facility in a lead cast to prevent contamination of people or other things during transfer. The cobalt-60 pencils are held on a source rack. Since most products must be exposed to the gamma rays for several hours, a conveyer moves the food past the source rack, stops, and then moves again. The cobalt-60 emits gamma rays continuously in all directions. A conveyer loops all the way around the sourcerack to take advantage of the gamma rays being emitted in all directions and to maximize efficiency. A standard gamma ray facility contains about one million curies (Murano 11-12). The curie is “a unit of radioactivity equal to 3.7*1010 disintegrations per second” (Webster’s “curie”). When new, each pencil contains about six-thousand to thirteen-thousand curies.
Electron beam facilities are the second type of irradiation plants. These plants do not use atomic radiation, but rather, an electron beam generator and require extensive electrical components and heat exchangers to cool them. The plants usually use an electron beam of five to ten million electron volts (Murano 15-16). However, a five megavolt beam from both sides of the food can only penetrate one and one half inches. The throughput is determined by the number of watts. Since the beam is directed at the product and not in all directions, the electron beam is more efficient. A ten kilowatt beam generator is as powerful as about one-million curies from a cobalt-60 source (Murano 14-15). The electron accelerators produce from five to ten million electron volts and ten to fifty kilowatts (Murano 15-16). The electron beam efficiency can be increased by aiming the beam at a metal target, usually tungsten or tantalum. This produces Bremsstrahlung x-rays. This type of x-ray can penetrate as well as gamma rays, but two-hundred kilowatts would be required to achieve necessary throughput.
Irradiation requires different levels of exposure for different tasks. The International System’s unit of radiation is the Gray (Gy). One Gray is equal to one joule of energy absorbed by one kilogram of food. A high dosage needed to sterilize food, as is done during canning, requires more than ten kiloGrays. A medium dosage, which can “pasteurize” food, is one to ten kiloGrays. A low dosage, which simply prevents ripening and kills insects or larger pathogens, is less then one kiloGray (Murano 5-6).
Irradiation plants must be licensed and are strictly inspected on a regular basis. The plants are completely automated; there is little room for human intervention. People are not exposed to the radiation on a normal basis. Sophisticated computer controls and machinery do the dangerous work. When the cobalt-60 is not in use, the sourceracks travel into deep tanks of water, and in electron beam facilities, the electron beam guns are turned off when not in use.
Irradiation has been approved worldwide in more than thirty-eight countries. More than thirty commercial irradiation plants are in operation (Murano 3). For example, Odessa, a port on the Black Sea, uses electron gun type irradiation to ionize two-hundred metric tons of fod per hour (Satin 16). Four-million tons of spices and seasonings and seven-million tons of poultry are irradiated in several facilities in France (Murano 4).
There are many advantages that irradiation holds over traditional methods of food decontamination. Irradiation can be used on meats, seafood, fruits and vegetables, and herbs and spices. Pathogens in food can be eliminated by cooking, but few people want to buy meats, fruits, and vegetables that have already been cooked. Chemical washes, steaming, and chlorinated ozone water baths, combined, are not as effective at killing pathogens as irradiation (Sihna 67). Also, irradiation of food can be done after the food has been packaged. This can seal out bacteria if the package is air tight. With other conventional methods, the food is decontaminated, then it is packaged. This leaves a chance for pathogens to reenter the food before or during packaging. In 1965 the surgeon general concluded that food irradiated with up to fifty-six kiloGrays is safe to eat (Murano 4). A list of approvals by the FDA concerning irradiation of specific foods and the year the approval was given is as follows: wheat and wheat flower may be irradiated with .2 to .5 kiloGrays for insect disinfestation, 1963; white potatoes can be irradiated with 0.05 to 0.15 kiloGrays to inhibit sprouting, 1964; spices and dehydrated vegetable seasonings can be irradiated with up to thirty kiloGrays to control microbial contamination, 1983; dried enzymes may be irradiated with up to ten kiloGrays, and pork carcasses and fresh pork cuts with 0.3 to 1.0 kiloGrays, 1983 (Murano 6-7).
Stephen Chapman from the Chicago Tribune says that “The Food and Drug Administration, which is about as hasty and reckless as your Aunt Minnie, has given the green light to food irradiation” (3). Since the Cold War, the nuclear industry has an interest in peaceful uses for radiation, such as irradiation. The use of irradiation to control food-borne disease and to fight world hunger has been endorsed by the Food and Agriculture Organization and the World Health Organization. These organizations say that the cost of decontaminating the whole food chain would be so high that simply irradiating contaminated food would be a better solution (Food Irradiation: Solution or Threat). “The critics make a good point, (sic) which is that the consumer ought to be paying attention to the advice of scientists. If the buying public does that, it will discover that the opponents of food irradiation have fewer allies in the scientific community than Jean Dixon,” says Stephan Chapman (3).
With all the benefits of irradiation, there is still concern among some. Drexler says “Even the FDA admits that it is impossible to assess the effects of eating irradiated food, because the usual scientific approach, exaggerating normal dosage, won’t work: Neither lab animals nor humans can eat normally irradiated food in large quantities, and they risk exposure to actual radioactivity if they eat food exposed to extremely high levels of radiation.” (60) More than a dozen of America’s poultry processors are against irradiation and will not use it to treat their chickens (Chapman 3).
Irradiation does have some problems in its current state. It has a limited range of use and is expensive. Irradiation has no effect against viruses. Michael Jacobson, the director of the Center for Science in the Public Interest, says irradiation is not “the silver bullet of improving the safety of meat products.” (Sihna 66-67) He says that food industries should spend more time experimenting with inexpensive chemical washes. He says that irradiation cannot replace clean and safe food processing habits. The International Consumers Union says that without investment from consumers, irradiation will not play a large role in the prevention of diseases.
Even though irradiation is very effective at decontaminating food, there is still room for human error during cooking. The food can still be cross contaminated by unwashed hands and other infected kitchen utensils. Consumers should be careful when handling irradiated foods; the food may be germ-free in the package, but most people’s kitchens are not.
Scientific studies have…established that irradiated food poses no danger whatsoever to human health. Irradiated food is not radioactive food. In fact, given what we’re learning about the state of the food-inspection system in the country, irradiated food is almost certainly safer than some of what is now available on supermarket shelves (”Food Irradiation a Promising Technology” 14).
“Food Irradiation a Promising Technology.” Atlanta Constitution. 12 September 1991. p. 14.
“Food Irradiation: Solution or Threat.” Consumers International. Accessed: 14 September 1999.
Available at: http:/188.8.131.52/consumers//campaigns/irradiaion/irrad.html
Chapman, Stephen. “Science and Myth in the Debate on Food Irradiation.” Chicago Tribune. 7 July 1991. p. 3.
Drexler, Madeline. “The Irradiation Debate.” Boston Globe. 11 November 1990. p 60-61. Murano, E. Food Irradiation a Sourcebook. Ames Iowa: Iowa State University Press, 1995. Satin, Morton. Food Irradiation a Guidebook. Lancaster, Pennsylvania: Technomonic Publishing Company, 1993.
Sihna, Gunjan. “Beefing Up Food Safety.” Popular Science. June 1998: pp. 4-67.