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Food irradiation is not a new technology. Research began in earnest with Presi- dent Eisenhower’s “Atoms-for-Peace” policy after World War II. Much of the early research was carried out by the U.S. Army and the Atomic Energy Commission. The first commercial use of food irradiation occurred in 1963, when the Food and Drug Administration (FDA) approved its use to control insects in wheat and flour. Large-scale implementation of food irradiation in the United States has been slow due to concerns about its safety. Realization that pathogens are the major concern in food safety has reignited interest in food irradiation.

BACKGROUND

Food irradiation is a method of controlling insect pests and pathogenic or spoil- age bacteria in food and agricultural commodities. Instead of using heat or chemicals for processing, irradiation uses gamma energy, electron beams, or X-rays. Sometimes it is referred to as cold pasteurization. Similar technology is used to sterilize medical equipment and devices so they can be used in surgery and implanted without risk of infection.

Food irradiation has different uses depending on the strength of radiation used. It can be used to control mold, inhibit sprouting in vegetables, control insect pests, re- duce bacterial pathogens, or, at the strongest dose, sterilize food. At low doses irradi- ation is an alternative to fumigation with chemicals to eliminate insects. Low doses have been used to inhibit the growth of mold in strawberries and to inhibit sprouting in potatoes, thereby prolonging the shelf life of these products. From 1995 to 1999

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approximately 800,000 pounds of tropical fruit from Hawaii have been irradiated before shipping to the mainland. This eliminated the need for fumigating them to destroy fruit flies that could spread to the mainland. Spices are the most widely irradi- ated product, with about 25 percent of the total world spice trade undergoing irradi- ation (Derr 1999). The current push for irradiation is to kill bacteria and parasites that would otherwise cause foodborne illness. The dose of irradiation needed to kill

Salmonella in chicken is about seven million times more than that of a chest X-ray.

NASA irradiates food that astronauts eat in space. Their food is irradiated to the level of sterilization.

Three different irradiation technologies exist, which use three different kinds of rays: gamma rays, electron beams, and X-rays (CDC 1999). The first technology uses the radiation given off by a radioactive substance. This can be either a radioac- tive form of the element cobalt (cobalt 60) or of the element cesium (cesium 137). These substances give off high-energy photons, called gamma rays, which can pene- trate foods to a depth of several feet. These particular substances do not make any- thing around them radioactive. This technology has been used routinely for more than 30 years to sterilize medical, dental, and household products. It is also used for radiation treatment of cancer.

Electron beams, or e beams, are produced in a different way. The e beam is a stream of high-energy electrons, propelled out of an electron gun. This electron gun apparatus is a larger version of the device in the back of a TV tube that propels electrons into the TV screen at the front of the tube, making it light up. The elec- tron beam generator can be simply switched on or off. No radioactivity is involved. The electrons only penetrate food to a depth of a little more than an inch, so the food to be treated must be no thicker than that. Two opposing beams can treat food that is twice as thick. E-beam medical sterilizers have been in use for at least 15 years.

The newest technology is X-ray irradiation. This is an outgrowth of e-beam tech- nology, and is still under development. The X-ray machine is a more powerful ver- sion of the machines used in many hospitals and dental offices to take X-rays. To produce the X-rays, a beam of electrons is directed at a thin plate of gold or other metal, which produces a stream of X-rays coming out the other side. Like gamma rays, X-rays can pass through thick objects. However, like e beams, the machine can be switched on and off, and no radioactive substances are involved.

Irradiation kills microbes by damaging their DNA. Because of this, bigger organ- isms like parasites and insects are more susceptible to irradiation because they have more DNA. A higher dose is necessary to kill bacteria since they have less DNA. Vi- ruses, which are very small and have very little DNA, are generally resistant to irradi- ation at the doses approved for use in foods. Not all foods are suitable for irradiation. The quality of some foods, such as eggs and shellfish, decreases below the point of consumer acceptability. Irradiation also changes some of the taste and texture quali- ties of foods. The higher the dose, the more pronounced the changes, just like in conventional cooking.

FDA and USDA are responsible for determining the safety of irradiation, setting the maximum dosage levels and approving packaging materials. When approval is granted by FDA and/or USDA to irradiate a food product, a specific maximum dose for that food is set. Materials used in packaging that will undergo irradiation with the food product must also be approved. The Nuclear Regulatory Commission (NRC) has responsibility for ensuring the safety of the facilities themselves, and the Depart-

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ment of Transportation for the safe transport of radioactive sources. E-beam and X-ray sources are monitored by the part of FDA that regulates medical X-ray devices. State authorities may also have a role in regulation of irradiation.

THE CASE IN FAVOR OF IRRADIATION

The technology to irradiate foods to make them safer has been available for de- cades, but it languished in legislative limbo brought about by those opposed to it. The current flurry of activity in favor of food irradiation started after the 1994 deaths of four children who died after eating hamburger meat contaminated with E. coli O157:H7 from a fast food restaurant. The 1997 recall of 25 million pounds of ham- burger meat from a major meat processing plant in Nebraska added fuel to the fire.

Proponents of food irradiation claim that the safety of irradiated foods has been studied by feeding them to animals and to people. These extensive studies include animal feeding studies lasting for several generations in several different species, in- cluding mice, rats, and dogs. There is no evidence of adverse health effects in these well-controlled trials. Irradiating foods does produce a very small amount of unique radiation products—about three milligrams per kilogram of food, equivalent to three drops in a swimming pool (Derr 1999). Even something that was toxic, and these substances have not been shown to be, would not be dangerous at that level. NASA astronauts eat foods that have been irradiated to the point of sterilization (substantially higher levels of treatment than those approved for general use) when they fly in space. In addition, proponents of irradiated food cite studies showing that irradiated foods do not differ substantially in nutritional value from non-irradiated food. Levels of the vitamin thiamin are slightly reduced, but not enough to result in vitamin deficiency.

Irradiation proponents emphasize that it is not a substitute for good sanitation. For irradiation to be effective, the food that is to be irradiated already needs to be clean. The more initial contamination there is, the higher dose of irradiation it would take to eliminate possible pathogens, and the greater the change in the taste and quality of the food. So, irradiating poor-quality or spoiled food will result in a prod- uct that will be of poorer quality after irradiation, making it impossible to sell. It is in the best interest of industry to irradiate clean, good-quality food. Irradiation adds an extra measure of protection to food, and is only one tool in the arsenal to fight foodborne pathogens.

Medical sterilization facilities have been operating in this country for more than 30 years, without a fatal accident. More than 100 such facilities are currently li- censed, along with at least that many medical radiation treatment centers and bone marrow transplant centers. No events have been documented in this country that led to exposure of the population at large to radioactivity. Most irradiation facilities use cobalt 60, which decays by 50 percent in five years. The cobalt is a solid metal that is stored in long cobalt “pencils,” which are shipped back to a nuclear reactor to be re- charged.

Proponents are convinced that the American public would accept irradiation if they understood it better. They have done surveys demonstrating that if people are educated about the process first, they will be in favor of it.

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Food is placed into a shielded chamber, an energy source is provided, the food absorbs the amount of energy necessary to accomplish the desired effect, the food is removed from the chamber, and is immediately ready to be further processed or consumed. (Derr 1998)

While the above description sounds like it could be describing high-tech food irradi- ation, it could also describe conventional cooking in an oven. The “chamber” would be a typical kitchen oven and the “energy source” gas or electric heat. It only appears to be a “high-technology” process because of the description given.

THE CASE AGAINST IRRADIATION

Opponents of food irradiation claim it is being pushed on consumers by agri-business, food processors, and the nuclear industry. Citing a 1997 CBS poll that found 73 percent of Americans opposed food irradiation and 77 percent said they wouldn’t eat irradiated food, opponents say it is just a big public relations ploy by the Department of Energy, the Nuclear Regulatory Commission, and the International Atomic Energy Agency to put a positive face on nuclear power. As with other biotech- nology issues, the food industry is heavily involved in lobbying Congress to pass laws in its favor. From 1995 to 1998 food industry political action committees gave $1,736,112 to the Democratic Party and $6,154,749 to the Republican Party (Hauter 1999). The food industry also contributes heavily to individual members of Congress who they lobby to support its pro-irradiation views. Critics remain convinced that the risks involved with food irradiation far outweigh the presumed benefits.

Health concerns of those opposed to irradiation center around the unique radia- tion products formed during the irradiation process. They fear that these completely new chemicals have not even been identified, much less tested for toxicity. Critics claim that irradiation destroys essential minerals and the vitamins A, B, C, E, and K, with a 20 to 80 percent loss not uncommon. Furthermore, viruses and bacterial spores not killed by irradiation could mutate into “superbugs.” Evidence of this pos- sibility is a non-pathogenic bacterium, D. radiodurans, which can survive very high levels of irradiation. Irradiation opponents claim to know of radiation-resistant strains of Salmonella have been developed in the laboratory (Meeker-Lowry 1998).

Irradiation foes claim that no long-term studies have been performed to examine the health effects of eating irradiated foods, and that some of the studies that have been done show harmful effects. They allege that even FDA admits studies used to prove the method is safe were flawed. Critics cite the following studies to bolster their views:

• In one study animals fed a diet of irradiated food experienced weight loss and miscarriage, almost certainly due to irradiation-induced vitamin E deficiency.

• Raltech Scientific Services, Inc., fed irradiated chicken to several different animal species. The studies indicated the possibility of chromosome damage, immunotoxicity, greater in- cidence of kidney disease, cardiac thrombus, and fibroplasia.

• In another study rats fed irradiated food may have developed kidney and testicular tumors. • A study from India found that four out of five children fed irradiated wheat developed a

chromosomal abnormality that may be related to future cancer development.

• In one experiment, cooked irradiated beef had seven times more benzene, a known carcin- ogen, than did cooked non-irradiated beef.

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Opponents point out that many of the studies proving irradiation is safe have been conducted in the test tube or on animals. Human studies have not been done, but we are about to embark on a very large human study by offering irradiated products in the marketplace.

Some of the consumer groups who previously opposed food irradiation on health grounds are focusing on the danger to workers in irradiation plants. They quote the Nuclear Regulatory Commission as reporting 54 accidents at 132 irradiation facili- ties since 1974. They claim that the nuclear industry wants to shift the burden of nu- clear waste from weapons production to consumers. They recognize that right now cobalt 60 is used, but claim that since it is in short supply, industry will use cesium 137, which is a waste product from nuclear power plants.

Another reason some groups oppose irradiation is because they believe food pro- cessors will rely on irradiation to sterilize food processed under unsanitary condi- tions. They point to the real causes of unsafe food as filthy farms and slaughterhouses and imported food produced under lax sanitation standards. Current large-scale production practices of crowding animals together in unsanitary conditions throughout the growing, transportation, and slaughter periods makes it impossible to keep fecal material out of meat products. The groups feel that these problems should be cleaned up rather than covered up with irradiation.

SOURCES

Centers for Disease Control and Prevention (CDC). 1999. Frequently Asked Questions about

Food Irradiation. Washington: Centers for Disease Control and Prevention.

http://www.cdc.gov/ncidod/dbmd/diseaseinfo/foodirradiation.htm

Derr, Donald D. 1999. You Asked . . . ? Foundation for Food Irradiation Education. http://www.food-irradiation.com/you_asked.htm.

Derr, Donald D. 1998. Food Irradiation—The Basics. Foundation for Food Irradiation Ed- ucation. http://www.food-irradiation.com/basics.htm.

Hauter, Wenonah. 1999. Food Irradiation: Do You Know Where Your Dinner Has Been? Washington: Public Citizen’s Critical Mass Energy Project.

Meeker-Lowry, Susan, and Jennifer Ferrara. 1998. Meat Monopolies: Dirty Meat and the

False Promises of Irradiation. Walden, VT: Food and Water.