Irradiation: Is Your Food Toxic? Skeptoid #61 August 14, 2007 Podcast transcript | Listen | Subscribe

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Today we're going to critically examine a mysterious green logo on the side of a food container in the supermarket. Many people believe this means the food is radioactive or poisonous. Some trust that it's simply sterilized. Which is true?

My grandmother went to her grave with the firm belief that eating food that had been warmed in a microwave would give you cancer. The similarities between the terms "microwave radiation" and "radiation poisoning" were all she needed to form this opinion. And, unfortunately, hers was no less rigorous than the process most people follow to form opinions about technologies or methods that they don't thoroughly understand. I offer most Americans' opinion of nuclear energy as a perfect example: Chernobyl = danger = nuclear reactors are fundamentally bad. Yet, how many of them can tell you anything about the closed fuel cycle reactors being designed today? Ever since the aftermath of Hiroshima, there has probably never been any word that incites so much fear as radiation.

The Radura logo indicates food that has been irradiated.

Simply put, irradiation is the process of blasting food with a shot of ionizing radiation, killing any microbes that would contribute to the food going bad sooner than it needs to. Bacteria, viruses, and everything else are all sterilized by the radiation. Ionizing radiation is used because it's high energy, and is extremely dangerous to living tissue. Three types of radiation are used: high intensity x-rays, which are high energy and penetrating; gamma decay, which is really high energy and does great damage, and consists of electromagnetic radiation in the form of photons; and beta decay, which consists of electrons that are too big and slow to do much by themselves, and so they need to be accelerated into a high energy state at nearly the speed of light. All three types have different characteristics in terms of how far they penetrate and how long an exposure is required, so different types are used for irradiating different foods. Whatever the method, the food coming out the other end — be it bread, milk, meat, fruit, or cheese — is absolutely sterile and, if properly sealed, will last longer on your shelf than virtually anything else in the supermarket.

How is irradiation such an effective killer? The high energy of ionizing radiation creates ionization events within the cells of tissue that it strikes. These ionization events result in chemical and even some nuclear reactions among the affected molecules. When this happens in DNA, it causes damage that, if the cell survives, can become cancer. At higher levels, sufficient damage is done to the cell that it's almost always killed outright. Guaranteed no salmonella or E. coli.

Irradiation is a cheaper way to bring safer food to the market. It's common in Europe, where refrigeration infrastructure has historically not been so great, but it's rare in the United States. The circular green logo along with the words "Treated with irradiation" are so terrifying to much of the American public that the process has been put virtually out of business. Most Americans would prefer to accept a few E. coli deaths than have their food exposed to a sterilization procedure that involves nuclear physics.

At this point in the podcast, some of you are tuning out and saying "Oh, there he goes again, towing the line of his corporate paymasters, saying whatever Halliburton is paying him to say, and talking down to people who question authority." Questioning authority is wonderful, and more people should do it. Unfortunately, most of those who claim to question authority are really just rejecting authority, for the sake of doing so. To truly question something, you have to listen, learn, and analyze.

During the anthrax scare of 2001, the US Postal Service had a lesson in analyzing. As an emergency measure, they contrived to irradiate the mail, as this would effectively kill any anthrax that anyone might be sending. Well, apparently they turned up the volume too high. They killed the anthrax, all right, but they also nuked the hell out of a lot of mail. Some stationery darkened horribly. Stamps were ruined, to the dismay of collectors. Photographic film was destroyed. Plans to irradiate all mail eroded, and now only mail to certain government offices gets this treatment. Apparently, you can overnuke stuff. Don't tell my paymasters I said this, but irradiation can be done wrong, and can have disastrous results.

Critics have pointed out that new, unexpected chemicals can be formed during irradiation, and this is true. Ionization is a chemical reaction. However, cooking, and most other food preparation techniques, cause the formation of new chemicals in dramatically higher concentrations, and this has never posed a problem. Every test ever done has found irradiated food to be safe.

But that doesn't mean they're always good. Some foods don't tolerate irradiation well. Some foods, most notably romaine lettuce, can smell bad, taste funny, or have their texture affected if they get overnuked. This is not a health concern, it's a culinary problem. The trick is to find the right dosage to kill any organisms and yet not affect the food. Almost all foods tolerate irradiation with no noticeable effects, but for some, the food gets ruined at doses too low to effectively sterilize it, and so these foods are not candidates for irradiation. For any food you see bearing the irradiation logo, you can be sure that it's been tested and its quality has been found to be unaffected by the dosage used. Not that this will satisfy consumers.

You see, a principal misconception held by many opponents of food irradiation is that the process of applying radiation leaves the food radioactive. This is completely false. This would be analogous to turning off the light in a room, and expecting the room to be residually contaminated with light radiation and still glowing. Obviously, this isn't what happens. Once the source of the radiation is removed or deactivated, there is no more radiation. It's like turning off a light. Food that's been irradiated is not radioactive.

Does this mean that you can take a fish fillet and set it outside your nuclear bomb shelter, let it marinate in the radiation, then bring it back inside and enjoy a healthy meal? No. In this case, heavy radioactive elements in the fallout dust would contaminate the fillet. When you brought it back inside, you'd bring in radioactive dust along with it, and you'll all get fried. The irradiated fillet won't hurt you, but the heavy radioactive metals sitting on its surface, still emitting particles, will. Food irradiation, and for that matter microwaving as well, does not place radioactive material onto the food. The food is placed in the radiation field, and then it's removed. Run a Geiger counter over it, and it shows zero. Food that's been irradiated is not radioactive.

Nobody has ever been sickened or harmed in any way by eating properly irradiated food, despite a few untrue claims made by the Sierra Club and others. However, many people die or catch severe bacterial infections from eating food that is not irradiated. Next time we have an E. coli breakout, step up to the plate and point out the benefits of irradiation. When lives are on the line, we should use every means at our disposal to properly sanitize our food supply.

And also use every means at our disposal to get Halliburton to finally send me my check.

Brian Dunning

References
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