What Is Food Irradiation and Is Food Irradiation Safe?

Food irradiation is the practice of producers’ subjecting their food products to intense fields of gamma rays, X rays, or high-energy electrons before shipping them to market. Why would they want to do this?

  1. Irradiation kills harmful bacteria, including E. coli, Salmonella, Staphylococcus, and Listeria, among others, thereby reducing the danger of food-borne illness.
  2. Irradiation kills insects and parasites without the use of chemical pesticides. (Many of the spices, herbs, and seasonings used in the United States today have for some time been irradiated for this purpose.)
  3. Irradiation inhibits the spoilage of foods, and can stretch the world’s available food supply. In more than thirty countries around the world, some forty different kinds of food, including fruits and vegetables, spices, grains, fish, meats, and poultry, are routinely being irradiated.

There are two classes of opposition to the widespread use of food irradiation. One centers on socioeconomic issues, and the other on safety.

The main socioeconomic objection is that food irradiation might be taken advantage of by the food industry for its own, self-serving purposes. Instead of cleaning up its less-than-satisfactory sanitation act, the food and agriculture industry might come to depend upon irradiation as an end-of-the-line cop-out to “neutralize” contaminated, sloppily produced meats and other foods.

I am no apologist for agribusiness, or for that matter for any enterprise whose sole purpose is to make money, even, when expedient, at the expense of public safety. There exists an undeniable history of illegal dumping of toxic wastes, for example, not to mention the collusion within a certain industry to conceal its knowledge of the lethal effects of burning and inhaling the smoke from its product. In this light it is difficult not to believe that food irradiation is tempting to food producers for what many would consider to be the wrong reasons.

But I hereby sidestep the political, social, and economic arguments for and against food irradiation, on which I have opinions in my role as a citizen, and focus purely on the scientific issues, which I deem myself more qualified to address. Only after the scientific facts are clear can the other issues be fought out with some semblance of objectivity.

Is food irradiation safe? Are airplanes safe? Are flu shots safe? Is margarine safe? Is living safe? (Of course not; it invariably ends in death.) I don’t mean to belittle the question, but “safe” is probably the most useless word in the English language. It is so loaded with contexts, connotations, interpretations, and implications that it loses all meaning. And, of course, a meaningless word belies the very purpose of language.

Any scientist will tell you that proving a negative is virtually impossible. That is, trying to prove that something (for example, an untoward event) won’t happen is futile. It is relatively easy to prove that something does happen; just try it several times and note that it happens. But if it doesn’t happen there is always the next time, and predicting the next time is prophesy, not science. When you come right down to it, science can deal only in probabilities.

Allow me, then, to rephrase the question. What are the chances, the probabilities, that consuming irradiated food will in some way produce unhealthful effects? The scientific consensus is “very slim.”

Here are some quick answers from a nuclear chemist (me), who in his time has both generated and been exposed to his share of radiation:

Do irradiated foods cause cancer or genetic damage? It has never happened.

Does irradiation make food radioactive? No. The energies of the radiations are too low to cause nuclear reactions.

Does irradiation change the chemical composition of whatever it irradiates? Of course it does. That’s why it works. More about this later.

One big problem is that many people first came upon the word radiation in the context of the “deadly radiation” (the media love to use that phrase) that spews from atomic bombs and broken nuclear reactors. But radiation is a much broader, and more benign, concept than that.

Radiation is any energetic wave or particle that is traveling from one place to another at approximately the speed of light. The lamp on your desk sends out visible radiation called light. The broiler element in your oven sends invisible infrared radiation to your steak. Your microwave oven sends microwave radiation into your frozen peas. Cell phones, radio, and TV stations send out radiations bearing inane chatter, trash music, and moronic sitcoms.

And yes, inside a nuclear reactor there are intense nuclear radiations emanating from radioactive materials, including the very same gamma rays that are used in food irradiation. These, along with the X rays and high-energy electron beams also used in food irradiation, are called “ionizing radiations,” because they have enough energy to break atoms apart into “ions”, charged fragments. They are indeed very dangerous for living things, from microbes to humans.

But the heat that we cook with is the very same heat that rages in the fires of Hell. You wouldn’t want to be in the oven alongside your roast any more than you’d want to be inside a nuclear reactor or alongside the food while it’s being irradiated. That doesn’t make either cooking or irradiation dangerous. It’s all a matter of who or what is being exposed.

X rays and gamma rays penetrate deeply into plant and animal tissue, doing damage to atoms and molecules in living cells along the way. These two kinds of radiations, along with beams of electrons, are used to irradiate foods precisely because they do damage the cells of insects and microorganisms, altering their DNA and preventing them from reproducing or even from staying alive.

Heat, of course, does the same thing. That’s why milk, fruit juices, and other foods are pasteurized by heating. But many germs are harder to kill than the bacteria that pasteurization is designed to deactivate. More drastic measures are necessary, but higher temperatures would change the taste and texture of the foods too much. That’s where irradiation comes in.

Ionizing radiations can break the chemical bonds holding molecules together, whereupon the fragments may recombine in new and unusual configurations, forming molecules of new compounds called radiolytic products. Thus, irradiation does indeed cause disruptive chemical changes. That’s how it kills bacteria. But while the changes in the bacteria’s DNA are lethal to them, the amount of chemical change in the food itself is minuscule at the radiation intensities used.

Ninety percent of the new chemicals formed are naturally present in foods anyway, especially in cooked foods. (Cooking causes chemical changes too, of course.) The other 10 percent? In more than four hundred studies reviewed by the FDA before approving food irradiation, no unfavorable effects were found from eating irradiated foods, either by humans or throughout several generations of animals.

While nothing, not even chocolate pudding, can definitively be shown to be absolutely “safe,” I believe in the well-known scientific principle that the proof of the pudding is in the eating. Apparently, so do the FDA, the USDA, the Centers for Disease Control and Prevention, the Institute of Food Technologists, the American Medical Association, and the World Health Organization, all of whom have approved the safety of various forms of irradiated foods.

A frequently expressed concern is that the widespread use of food irradiators would pose a serious problem of radioactive waste disposal. Mindful of the huge amounts of intensely radioactive waste generated during the reprocessing of nuclear reactor fuels, people may naturally wonder about the disposal of used food irradiators. But food irradiators, dangerous as they are, are as different from a nuclear reactor as a flashlight battery is from an electric generating plant. Radioactive materials are indeed being used, but there is no waste buildup from their use.

Let’s look at the hazards of the three types of food irradiators, one at a time.

X rays and electron beams used in food irradiation disappear like lamp light as soon as the switch is turned off. There is no lingering hazard and no radioactivity involved at all.

Cobalt-60 irradiators have been used safely in cancer therapy for decades all over the world. The radioactive cobalt, which must be shielded from people by massive concrete walls, is in the form of little “pencils” of solid metal that can’t leak. No one is going to throw one into the nearest creek.

Opponents of food irradiation point out that in 1984 a cobalt radiotherapy unit somehow found its way to a scrap yard in Mexico, its radioactivity eventually winding up in recycled steel consumer products such as table legs. But that was not a matter of radioactive waste. It was a deplorable instance of either stupidity or cupidity, two traits that no amount of precaution or regulation can erase from the human psyche.

Cesium-137, the other radioactive gamma ray source used in some irradiators, is in the form of a powder encapsulated in stainless steel. A byproduct of reactor fuel reprocessing, its half-life is thirty years, so after its long useful lifetime is over it can be returned to reactor waste as one more grain on the sand pile. A cesium-137 source being used for the sterilization of medical supplies did leak disastrously in 1989, but the problem is understood and has been fixed.

Here are some of the commonly voiced “technical” objections to food irradiation:

“Food irradiation uses the equivalent of 1 billion chest X rays, which is enough radiation to kill a person 6,000 times over.”

How is that relevant, I ask? Food irradiation is used on foods, not on people. In a steel mill, the temperature of the molten steel is 3,000ºF, which is hot enough to vaporize a human body. Workers in steel mills and food irradiation facilities are therefore well advised not to bathe in vats of molten steel or take naps on the food irradiation conveyor belts.

“With each bite of irradiated food we receive indirect exposure to ionizing radiation.”

There is absolutely no radiation in the food, either direct or indirect, whatever that means. With each piece of steel we touch, do we receive “indirect exposure” to that 3,000º temperature?

“Ionizing radiation can kill beneficial microorganisms as well as dangerous ones.”

That’s true. So do canning and virtually all other food preservation methods. But so what? A serving of food without beneficial microorganisms is not harmful.

“Ionizing radiation cannot discriminate between, for instance, E. coli bacteria and Vitamin E. Everything in its path can be changed, including nutrients.”

That’s also true to some extent, depending on the food and the radiation dose. But I don’t see the loss of some vitamins as a reason to ban the sterilization of foods by irradiation. All food preservation methods change the nutrient profile of foods to some extent. And I doubt if anyone’s diet is going to be limited exclusively to irradiated foods.

So, is food irradiation safe? Can anything be proven to be absolutely safe? Just read the finely printed “possible side effects” notice in every package of health-giving and lifesaving prescription drugs. We would have no marketable drugs if “absolute safety” were the criterion for approving new medicines.

As pointed out by James B. Kaper, Professor of Microbiology and Immunology at the University of Maryland School of Medicine, who has seen the devastating effects of E. coli poisoning in children, “Perhaps some minor adverse effects might eventually be linked to ingestion of irradiated food. But by that time, many people, mostly children, will have died from E. coli when they would have been protected by ingesting irradiated food.”

Life is a continual risk-benefit analysis; some degree of risk is the inevitable dark shadow of any technological advance. Until the last decade of the nineteenth century, for example, we had no electricity in our houses.

In the last decade of the twentieth, an average of more than two hundred people were electrocuted in the United States each year from household electrical devices such as lamps, switches, TVs, radios, washers, dryers, and so on, with another three hundred killed in some forty thousand electrical fires. We deplore and yet accept these consequences of having electricity in our homes because the benefits so vastly outweigh the risks.

We must compare the benefits of preserving foods and destroying harmful bacteria, insects and parasites, of stretching the world’s food supply and saving lives, against the vastly less likely, and certainly not life-threatening, risks.