Biomedicine

Food Irradiation: Will It Keep the Doctors Away?

Every major food and health organization has endorsed food irradiation as a foolproof and safe way to rid our food supply of disease-causing microbes. Then why aren’t we using it?

In food we trust. That motto guides us as much as the one that graces our currency. We take for granted the food we buy in grocery stores or eat in restaurants, trusting implicitly that it will satisfy our hunger, build strong bodies 12 ways, and keep us healthy.

That trust may be a bit misplaced. Nearly 200 people in the United States, most of them children or elderly, die each week from illnesses they contract from food. Estimates from the Centers for Disease Control and Prevention in Washington, D.C., suggest that 6 to 33 million people are stricken with food-borne diseases each year. Major outbreaks are grabbing headlines with greater frequency-consider the recent Hudson Foods recall of 25 million pounds of bacteria-tainted beef, contaminated Jack-in-the-Box hamburgers, Odwalla apple juice, and Guatemalan raspberries-while many minor ones go unreported.

Late this spring, President Clinton gave voice to growing concern by public-health officials over our food supply by calling for “new steps using cutting-edge technology to keep our food safe.” One of the technologies that Clinton singles out in his proposed $43 million National Food Safety Initiative is food irradiation, a process that has long been lauded by food-safety experts even as it languishes in the backwaters of research and development. “If the president’s program takes hold, food irradiation could get the political push it needs,” says James Tillotson, director of the Food Policy Institute at Tufts University.

This story is part of our November/December 1997 Issue
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“The benefits of food irradiation are overwhelming,” says Richard Lechowich, director of the National Center for Food Safety and Technology at the Illinois Institute of Technology. High-energy radiation kills critters that live in or on food, including the deadly E. coli O157:H7 bacterium and the salmonella and campylobacter species of bacteria found in most uncooked chicken and turkey. “Widespread irradiation of poultry alone in this country could prevent thousands of illnesses and hundreds of deaths every year,” concurs Douglas Archer, former deputy director of the Center for Food Safety and Applied Nutrition at the U. S. Food and Drug Administration (FDA).

A major benefit of irradiation is that it can occur after food is packaged and sealed to kill any organisms that may have contaminated the food between production line and plate. “We don’t live in a perfect world where we always detect E. coli on a processing line, and where everyone washes their hands and cutting boards and cooks meat and poultry to the proper temperature,” says Christine Bruhn, director of the Center for Consumer Research at the University of California at Davis. Food irradiation is like an air bag in a car, she says. Both offer an extra measure of safety in case of carelessness or accident.

More than 40 countries share this view, having authorized irradiation for everything from apples in China and frog legs in France to rice in Mexico, raw pork sausages in Thailand, and wheat in Canada. Irradiation has been endorsed not only by the U.N. World Health Organization and the Food and Agriculture Organization, but also by the U.S. Food and Drug Administration, the American Medical Association, and the American Public Health Association, among others. The process can legally be used in the United States for killing insects in grains, flour, fruits, and vegetables; for preventing stored potatoes, onions, and garlic from sprouting; and for killing microbes, insects, and parasites in spices, pork, and poultry.

But despite such wide-ranging approval, actual use of irradiation in the United States has been limited. Astronauts have eaten irradiated food ever since the Apollo 17 moon shot in 1972, when they carried sandwiches made from irradiated ham, cheese, and bread. Space shuttle crews dine on radiation-treated food, and it will almost certainly show up on space station menus. Some hospitals and nursing homes serve irradiated chicken to people with weakened immune systems, including AIDS patients, burn victims, people undergoing chemotherapy, and patients who have just had a bone marrow or organ transplant. And a few independent grocers carry irradiated produce and poultry. But the vast majority of companies that grow, process, or sell food shy away from this technology.

Why? The food industry has been reluctant partly because of public fear of radiation. In fact, a savvy organization of activists known as Food and Water claims it has held food processors in check simply by threatening to expose any company that dares use the technique. But that may change. Advocates contend that such fears of irradiated food are not only groundless but, with each news report of contaminated food, fading quickly as consumers consider the alternative of ignoring this safeguard. The issue now, they say, is whether the technology is ready for commercial use and can work at reasonable cost.

Roots of Irradiation

Although food irradiation is often referred to as a cutting-edge technology, its beginnings stretch back nearly a century. A few years after radiation was discovered by French physicist Antoine-Henri Becquerel in 1896, Samuel Prescott, professor of biology at MIT, showed that gamma rays from radium destroyed bacteria in food and proposed using radiation to preserve meat, fruit, vegetables, grains, and other foodstuffs. In the 1920s and 1930s, the United States and France awarded patents for radiation-based methods of killing parasites in pork and bacteria in canned food. Some 25 years of research at MIT and U.S. Army research facilities-from 1943 to 1968-further demonstrated its potential for treating and preserving food.

This high-tech cousin of canning, freezing, and fumigating relies on a simple principle that children of the atomic age know by heart: radiation kills, or at least alters, living cells. When gamma rays or other types of ionizing radiation zip through a cell, they knock some electrons out of their orbits, breaking chemical bonds and leaving behind a trail of ions and free radicals-atoms or molecules with an unpaired electron. These highly reactive substances crash into each other and into their nonirradiated neighbors, creating some new compounds and reforming many that had originally been there.

When a cell is exposed to high enough doses of radiation, the maelstrom of chemical reactions inside an irradiated cell inactivates key enzymes, irreparably damages the cell’s genetic instructions, and can disrupt its protective outer membrane. The cell either stops growing and fails to reproduce or dies outright. Either of these outcomes destroys organisms that are natural or introduced contaminants of food or other products or prevents them from multiplying.

Examining the Evidence

Though some foods such as cucumbers, grapes, and some tomatoes turn mushy when radiation breaks cell walls and release enzymes that digest the food and speed up rotting, many others including strawberries, apples, onions, mushrooms, pork, poultry, red meat, and seafood emerge from irradiation intact and edible. But while these foods can legally be irradiated, virtually none of them are.

The problem isn’t necessarily radiation itself, because people don’t seem to mind that it is used to sterilize half of all sutures, syringes, intravenous lines, and other medical supplies, as well as billions of dollars worth of consumer goods ranging from plastic wrap and milk cartons to tampons and contact lenses. What poses concerns is the juxtaposition of food and irradiation. “Food is a very emotional thing,” says Tillotson of Tufts. “We don’t want scientists or anyone else mucking around with it, especially not with something that most people link with the atomic bomb.”

The activists at Food and Water of Walden, Vt., effectively manipulate this potential reaction. This grassroots group, founded in 1984 to fight hunger, now spends its time fighting food irradiation, genetic engineering, and other technologies used to grow and process food, while advocating a smaller-is-better, back-to-the-land approach.

Tougher Testing

Opponents of food irradiation argue that critical tests remain to be done before anyone can say the process is absolutely without risk. Colby argues for standard toxicology tests that would involve irradiating an apple, say, then extracting any radiolytic products that form and feeding those compounds to lab animals at doses hundreds of times higher than that found in irradiated food.

But Josephson, for one, thinks that this exercise is unnecessary. “Why should we feed animals huge doses of these compounds,” he says, “when years of animal-feeding studies have already shown that the small amounts that occur in irradiated food don’t cause any health or reproductive problems?”

Food and Water adviser Donald Louria, chair of preventive medicine and community health at the University of Medicine and Dentistry of New Jersey, would go one step further than Colby. He says government or industry should fund a study in which volunteers of different ages, races, and socioeconomic backgrounds eat irradiated foods under controlled conditions, and then undergo tests to see if they have higher-than-normal levels of cells with chromosomal abnormalities.

On that score, however, the FDA apparently disagrees. Back in 1958, Congress defined irradiation as an additive rather than a process, even though radiation generates the same sorts of chemical byproducts in food as other processes used to preserve and protect food, including freeze drying, frying, sun drying, and canning. And FDA regulations don’t require human studies for food additives, especially when the compounds added are identical to those already found in food, says George Pauli, the FDA’s senior food irradiation scientist.

Ironically, neither Food and Water nor any other group is calling for the FDA to reclassify or restudy other techniques that produce the same byproducts. In fact, until the U.S. Army animal experiments, canned food had never been rigorously tested to see if it caused cancer. “People in the canning industry were holding their breath,” recalls Josephson, “hoping we weren’t going to find that canned food caused problems compared with irradiated food.”

Propaganda Campaign

Food and Water’s arguments may be shaky, but its public-relations acumen is rock solid, and highly effective. The organization deftly links people’s worst fears about radiation to food. For example, one classic Food and Water advertisement shows a mushroom cloud erupting from a freshly cooked hamburger. The message reads: “The Department of Energy has a solution to the problem of radioactive waste. You’re going to eat it.”

The organization knows how to pressure executives who fear any sort of public controversy. When Food and Water learned that a representative from Hormel Foods attended a 1996 symposium on the benefits of food irradiation, it demanded to know the company’s official policy on this technology.

When letters failed, Food and Water sought help from its constituents, which Colby claims total some 100,000, though a recent Wall Street Journal article places that figure considerably lower, at around 3,500. Colby asked members of Food and Water’s grassroots network to let Hormel know how they felt about irradiation, and supplied preprinted postcards and a listing of Hormel’s toll-free phone number.

The organization also ran a full-page ad showing a glowing can of irradiated Spam-one of Hormel’s most widely recognized products-in the company’s hometown newspaper on the day of its annual stockholder meeting and threatened Hormel officials that it would run the ads nationwide. Copies were sent to 18,000 food-industry executives. Two weeks later, Hormel issued a statement saying that it does not irradiate food. Food and Water suspended the campaign but threatened to resurrect it if Hormel “ever considers using food irradiation in the future.”

Colby calls this approach “corporate education” and grassroots activism. Others see it differently. “The organization is shaping the debate and food policy through public fear mongering and scare tactics,” says UC Davis’s Bruhn.

Technological and Economic Hurdles

Food and Water’s anti-irradiation campaign may be the most public obstacle to wider use of food irradiation, but it isn’t the only one. “The real barrier is economics and the bottom line” says Martin Stein, president of GrayStar, which is designing a food irradiator that can be installed in existing food-processing plants. In fact, a quick review of the methods the food industry could employ to generate ionizing radiation-using gamma rays from radioactive cobalt-60 or cesium-137, and electron beams or x-rays from linear accelerators-shows that the options have shortcomings that diminish their cost effectiveness, while improved models are still on the drawing board.

Gamma rays: Anyone interested in irradiating food today would probably turn to a cobalt-60-based system like the one in Mulberry, Fla., the first commercial facility dedicated to irradiating food. The heart of the plant, established in 1991, is a shiny rack of 400 gamma-ray-emitting cobalt-60 “pencils,” each 18 inches long and the diameter of a fat crayon, housed in a chamber surrounded by a concrete wall 6 feet thick. When not in use, the rack is submerged in a 15-foot-deep pool of cooled water that absorbs and neutralizes the gamma rays. At the push of a button, hydraulic arms lift the cobalt rack out of its protective pool and tall metal boxes packed with food slide into the irradiation chamber on an overhead monorail. The boxes follow a zig-zag pattern around the radioactive rack so gamma rays can reach all sides. Treatment times vary-fresh strawberries pass through in 5 to 8 minutes, frozen chicken takes as long as 20 minutes.

Gamma rays from cobalt-60 can penetrate full boxes of fresh or frozen food. But food must be removed from standard shipping pallets, stacked into metal irradiation boxes, and then returned to the pallets when they emerge from the chamber-all extra labor that increases costs.

A new irradiator now under development by GrayStar promises to address this concern by accepting food loaded onto standard pallets, something “everyone in the food industry says is an absolute must,” says Stein. The unit will generate gamma rays using cesium-137, which GrayStar would chemically separate from high-level nuclear waste now stored at several power plants around the country.

The prototype machine-which measures 10 feet wide, 8 feet long, and 28 feet high, 12 of which are underground-is de-signed to be in-stalled along a meat-packing or food-processing line. After a standard
pallet of packaged food rolls into the irradiation chamber, which is constructed from 16-inch steel walls, the operator will seal the doors and in-struct a computer to raise the rectangular array of cesium-containing rods from underground for a programmed length of time. Stein is optimistic that the unit will prove attractive to food processors and packers who may be more willing to invest in small, in-house irradiators than build, or contract with, a large central plant to which it must ship food. A working prototype of the compact unit, he says, is still a year away.

Electron beams and x-rays: Linear accelerators can generate ionizing radiation for food processing in the form of electron beams. Like a television set, these devices produce electrons from a heated filament sitting inside a vacuum tube. Magnetic fields accelerate the electrons through the tube until they reach energies as high as 10 million electron volts. At the end of the tube, meat or other food is irradiated as it slides by on a conveyor belt. Turn off the juice and the radiation disappears. A linear accelerator delivers more radiation per second than gamma rays, so it may work more quickly than a cobalt- or cesium-based machine.

“The downside is that electrons don’t penetrate more than an inch and a half. Thus electron beams would not be able to handle such items as boxes of fruit or sides of beef. However, says Dennis Olson, a professor of food science at Iowa State University who has been testing this method, “you could handle a product up to about three inches thick, something like hamburger or chicken breasts, if you irradiate from both sides.” Electron-beam units for such thin food products could move from the lab to the factory within a year or two at today’s pace of development, according to Spencer Stevens, president of Omaha-based APA, Inc., an engineering and consulting firm for the food and meat industry.

Olson and others are also exploring the use of x-rays for irradiating food. While it takes even more energy to make x-rays than it does to generate electron beams, thus lowering the efficiency of the process, x-rays have dramatically better penetrating power and could be used on stacked boxes of fresh or frozen food or on slabs of meat.

The Bottom Line

Economics will play a large role in determining which of these approaches, if any, will ever be widely used in food processing. As commodities go, food is cheap, so even slight increases in processing costs can have a big impact on what consumers pay for certain items. Thus, says Stevens, radiation processing can’t cost more than a few cents a pound, a figure that in-house irradiators could soon meet.

But the biggest unknown, of course, is whether consumers will buy irradiated food, even if producers can provide it at an affordable price. A series of surveys from the University of California at Davis, the University of Georgia, and Indiana University suggest the public is ready. “When you ask people if they would ever buy irradiated food, 50 to 60 percent say they would,” says UC Davis’s Bruhn. “When you mention that irradiation can keep food fresh longer and kill bacteria, the percentage rises to 80.”

In-store tests and actual sales from a few independent grocery and produce stores offer real-world evidence that consumers might follow through on what they say. For example, Olson and his colleagues at Iowa State University sold irradiated chicken at a grocery store in Manhattan, Kans. Radiation-treated chicken-clearly labeled with a green symbol called a radura that must legally appear on all irradiated food-was displayed next to the traditionally processed store brand. Whichever one was cheaper sold better. Sales split down the middle when both carried the same price tag. Even when the irradiated chicken cost almost 25 cents a pound more, it still accounted for 20 percent of sales, says Olson.

Carrot Top, a produce store in north-suburban Chicago, also has had success selling irradiated food. Owner Jim Corrigan first introduced irradiated strawberries in 1992 with a two-for-one sale, expecting his customers to buy a box of irradiated strawberries and one of nonirradiated strawberries for comparison. Instead, the berries treated with radiation, which killed the molds normally growing on the fruit, outsold untreated berries ten-to-one because they looked better and lasted far longer. Carrot Top has since expanded its irradiated line to include Vidalia onions, blueberries, chicken, exotic Hawaiian fruits, and any other irradiated foods that are available. “I would carry irradiated hamburger today if it were available, since my customers ask me for it,” says Corrigan.

Building Incentives

None of the country’s major food companies will publicly acknowledge even a remote interest in food irradiation, yet several developments could push the food industry to adopt irradiation. First, some “traditional” methods for ridding food of pests are under close scrutiny. Methyl bromide, used to fumigate cereal grains, dried fruits and nuts, and fresh fruits and vegetables is scheduled to be banned in the United States as of January 1, 2001. Not only is it toxic to workers-the Environmental Protection Agency classifies it as a Category I acute toxin, the most deadly kind-it also is 50 times more destructive to the ozone layer than chlorine atoms from chlorofluorocarbons. Radiation could offer a reasonable alternative.

Ionizing radiation can also replace ethylene oxide, another widely used toxic fumigant. Radiation kills bacteria and insects more efficiently than the ethylene oxide, says Thomas Mates, general manager of SteriGenics, a California company that owns and operates several medical irradiators. What’s more, irradiation doesn’t leave behind any residue, and doesn’t require any moisture, which can remove some of the volatile chemicals that give spices their smell and taste. SteriGenics recently introduced a line of radiation-treated spices called Purely by Choice.

The changing nature of our food supply may also spur wider use of irradiation. Once upon a time Americans got their food from local growers and neighborhood markets. Today much of our food comes from afar-from across the country and, increasingly, from developing countries. Few of us would eat fruits and vegetables in many of these countries without washing and peeling them. Yet when they are imported and sold in a U.S. store, that concern seems to disappear. “One does not need to leave home to contract traveler’s diarrhea caused by an exotic agent,” according to a recent editorial in the New England Journal of Medicine by Michael Osterholm, head of the Minnesota Department of Health. Food irradiation, he contends, “provides the greatest likelihood of substantially reducing bacterial and parasitic causes of food-borne disease associated with numerous foods, including fresh fruits and vegetables.”

Irradiation may get a huge political boost, not to mention funding for further research and development, from the Clinton Administration’s food-safety initiative, which is just beginning to wend its way through Congress. Whatever the outcome of the plan, however, the most powerful stimulus for wider use of irradiation is likely to be the ever-larger settlements awarded to people who become sick from eating contaminated food.

A generation ago, individuals felt responsible for the safety of their own food, says Christine Bruhn from UC Davis. Now people blame food growers, processors, and food sellers when they get sick from eating contaminated food, she says. This shift, already seen in million-dollar settlements such as those against Holiday Inn at San Francisco’s Fisherman’s Wharf and Foodmaster, the parent company of Jack-in-the-Box, is making restaurant owners and grocers take extra steps to make sure the food they deliver or sell is as safe as it can be.

Even though consumers seem willing to buy irradiated food, “it will probably take some truly traumatic E. coli outbreak that causes a number of deaths before government and the food industry get serious about food irradiation,” says James Tillotson of Tufts. Without such a crisis, consumers probably wouldn’t think of demanding irradiated food and there would be little political push to require leaving companies that explore irradiation open to attack by activist groups such as Food and Water. “No one is willing to get that kind of attention,” he says, “even when they might be doing the best thing for consumers.”

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