Food Irradiation

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Illustration by Fotolia/Lack-OKeen
Although the term "food irradiation" might sound ominous, research into its long-term health effects have been inconclusive.

The hazards imposed upon all life forms by today’s worldwide arms race prove beyond question that Dwight Eisenhower’s “Atoms for Peace” program has been an utter failure. The development of nuclear power plants has undoubtedly abetted the spread of the bomb to a steadily lengthening list of countries. And, in any event, atomic electricity seems on the verge of being declared an economic bust. What’s more, practical uses for bombs—such as the foolhardy scheme for excavating new Panama canals—have, thankfully, never materialized. There is, however, one vestige of Ike’s program that, after 30 years of dormancy, is enjoying a new burst of enthusiasm.

Food irradiation, the process of bathing edibles in heavy doses of gamma radiation to preserve them, was first put into practical use by the U.S. Army back in 1953. The Quartermaster Corps found that irradiated rations would last much longer than food preserved by conventional means, such as heat. Onions, for example, would stay fresh for 16 months, whereas untreated bulbs would sprout within 90 days.

Since the 1950’s, food irradiation has seen limited practical application in the U.S. (The meals packaged for our astronauts provide one celebrated example of the technique’s success.) On a commercial basis, stored wheat and white potatoes have been treated since 1964, and in July of 1983 the Food and Drug Administration (FDA) decided to allow the use of up to one megarad (a million rads, which is a unit of absorbed ionizing energy) to retard the growth of microbes in spices. The FDA also allows the export of irradiated foodstuffs to any of the roughly 20 countries that permit the practice.

The lack of general acceptance of irradiation for food preservation in the United States stems from the Food, Drug, and Cosmetic Act of 1958, which classified irradiation as a food additive, rather than as a food processing technique. As a result, irradiation’s proponents have had to prove that treating food with gamma radiation poses no hazards to human health. Of course, a chemical food additive can be tested with comparative speed and ease by administering large doses of the substance to animals. However, the same approach can’t be used with radiation: Exposing food to doses thousands of times greater than the norm simply destroys it. Furthermore, there are limitations on how much food can be fed to a laboratory animal. As a result, expensive and lengthy studies of long-term (chronic) effects are required.

And as you’ll soon find out, thorough examinations of the effects on humans of eating food that’s been treated with radiation have not been done. Nonetheless, the FDA is under heavy pressure to approve additional uses of the technique. In November, 1983, Representative Sid Morrison of Washington introduced legislation that would reclassify irradiation under the Food, Drug, and Cosmetic Act as a food-processing technology. This would allow the FDA to go ahead with its intention of permitting irradiation with up to 100 kilorads (a tenth of a megarad) on most foods.

Easy Now

The very word irradiation will bring on a quickening of the pulse in many people. In fact, the topic is sensitive enough to require that we be cautious about jumping to conclusions. If there’s one thing that all of the people embroiled in the controversy agree on, it’s that there’s no residual radiation in irradiated food. But, by the same token, we need to be careful about accepting the general proclamations of safety that are being widely issued in favor of the process. Food irradiation is fairly simple in concept but has very complicated ramifications.

Atoms For Pizza

A basic food irradiation unit costs about $2 million, so we shouldn’t expect to be putting up our garden vegetables with a home irradiator any time soon. The device consists basically of a thick concrete chamber with a pool of water for a floor. Racks of food are introduced into the processor, and radioactive rods are lifted from the pool. The distance between the food and rods, the time of exposure, and the intensity of radiation determine the total dose.

Radiation displaces electrons (the phenomenon is called ionization), producing what are known as free radicals. At exposures of around 100 kilorads, sufficient free radicals are produced to inhibit cell division in anything living in the food. Higher levels (a megarad or more) kill all organisms. Today, the widest use of irradiation is to cleanse hospital instruments; about 40% of the medical sterilization in the U.S. relies upon this technique.

The most popular irradiation material is cobalt 60, though cesium 137 is also effective. (Electron beams and X-rays work, too, but are less efficient and more costly.) Most of the cobalt 60 used for food preservation is salvaged from the waste products of the Canadian-designed CANDU reactor, though it could be separated from the waste of most reactors. Cesium 137 is a by-product of nuclear weapons material processing.

Both the nuclear power industry and military processors would be delighted to see food irradiation achieve wider acceptance. Radwaste that is now a major disposal problem could become a commercially useful product. Of course, these substances would eventually end up as waste for the food irradiation industry. Cobalt 60 has a half-life of 5.3 years, so its usefulness is limited. From a concerned citizen’s viewpoint, however, the material at least would be considerably less radioactive when it finally did become waste.

Is It Healthy?

Though there’s no radiation to be found in food that’s been zapped, there are chemical reactions brought on by the bombardment. Some of the nutritional components in the edibles are altered, and substances called radiolytic products are formed. Most of these changes aren’t particularly unusual or alarming. Treatment with heat reduces food value, too, and the majority of the radiolytic products formed are found in other types of consumables.

Irradiation destroys several vitamins—including A, some B’s, C, and E—and appears to affect important nutritional compounds such as proteins. So if irradiation is added to the list of systems used to process food, there’s very likely to be an overall loss of nutritional value.

Exposing comestibles to gamma rays also produces some radiolytic products that are not normally found in food. Over 40 of these compounds have been identified, but very little is known about their health effects. Most of the studies have been inconclusive, though there is some evidence that consuming irradiated food may cause reproductive and mutagenic effects. Polyploidy — the development of abnormal white blood cells in children — has shown up in two Indian studies on monkeys fed wheat irradiated with 74 kilorads. Additionally, Indian studies have found that irradiation causes an increase in aflatoxin (a potent carcinogen) in wheat that contains the aspergillus fungi. Research has also turned up testicular tumors and kidney disease, and the incidence of other health effects has been shown to be related to the level of radiation dosage of food fed to test animals.

Amazingly enough, though about 20 countries have been using irradiation for a number of years, no population studies into possible health effects have been done. And of the 413 animal studies the FDA reviewed in 1982, 344 were found to be inconclusive, 32 showed adverse health effects, and 37 were interpreted as evidence of safety. This pretty well typifies the current state of knowledge about the risks of irradiation. No definite threats to human health have been identified, but precious little evidence confirms the supposedly benign nature of the process.

How Well Does It Work?

Irradiation is not a food processor’s panacea. It requires a major capital investment to get started, and skilled staff must operate and maintain the equipment. Irradiation also just isn’t suitable for some jobs. Most fresh fruits and vegetables can’t successfully be preserved with the technique, because it causes browning and abnormal ripening. Dairy products aren’t likely to receive the treatment either, because it causes unpleasant odors.

The use of gamma rays to control spoilage of meat has been widely heralded as a way to reduce the use of nitrites and nitrates (which can form cancer-causing nitrosamines), but you should keep in mind that, at most, the use of these substances can only be cut by 80%. Irradiation has also been heralded as a replacement for dangerous pesticides such as EDB. With some foods — Hawaiian papayas, for example — the technique is very effective, but doses great enough to cleanse citrus fruit cause cosmetic damage. In short, radiation treatment may be able to replace some of the dangerous additives and pesticides now used on our food, but it won’t do away with all of them.

Food For Thought

At this time, we don’t believe that there’s enough evidence concerning the effects of food irradiation upon which to base a decision about its safety. If you’re ardently antinuclear, you may choose to oppose irradiation simply because it might breathe a little life into the nuclear industry. On the other hand, if you’re strongly opposed to the use of pesticides and chemical food additives, you might rationally see a lot of promise in irradiation. For those of us who take issue with both the nuclear and chemical industries, the choice is difficult.

Whether you choose to support or resist irradiation of food, you should know that the passage of Representative Morrison’s bill could remove the requirement for labeling a food as treated with radiation. Even the euphemistic preferences of the irradiation industry — “processed with picowaves” and “processed with ionizing energy” are a couple of examples of the sort of phrasing proponents have offered — would be preferable to no labeling at all.

Perhaps the best approach to the problem has been expressed by Dr. John Gofman, a medical physicist and expert on the health effects of radiation (see John Gofman: Nuclear and Anti-Nuclear Scientist): “The kind of epidemiological study required to find out whether or not a diet of irradiated food will increase (or possibly decrease) the frequency of cancer or genetic injuries among humans simply has not been done …. It is probable that we shall never know whether or not irradiated foods are safe …. I have no objection to the sale of irradiated food to willing buyers — provided that the buyers are not tricked into buying it (a) by false claims about its safety and/or (b) by inability to detect that irradiated food is what they are buying.”

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