Zapped! How Irradiation Is Threatening Our Food System

The following is an excerpt from the book Zapped! Irradiation and the Death of Food by Wenonah Hauter (Food & Water Watch, 2008).

Over the decades, the effects of irradiation have been compared dismissively to sunlight and glibly to atomic bombs -- and many images in between. Few grasp it completely, one of many reasons for its obscurity. Though the issue is kaleidoscopic, one needn't be an expert in physics or food science to gain a basic understanding.

Knowing what irradiation isn't is just as important as knowing what it is, if not more so. Irradiated foods don't glow in the dark. It doesn't make food measurably radioactive, though a mind-boggling FDA ruling could change this by dramatically increasing the maximum allowable radiation dose. And you won't sprout a sixth finger if you eat the stuff.

Now for what irradiation is. It uses astronomically powerful blasts of X-rays, electron beams, and gamma rays to kill bacteria, to extend shelf life of food by delaying ripening and spoiling, and to eradicate fruit flies and other invasive pests.

Here's where a little chemistry and physics come in. This radiation is ionizing, meaning it has enough energy to blow apart molecules and eject electrons that then bounce around crazily to form new bits of matter. On the opposite end of the spectrum, non-ionizing radiation such as microwaves, infrared, and visible light can't smash molecules. The industry commonly exploits this misunderstood subtlety to confuse the public by inferring that irradiation is just like microwaving.

No matter what type of facility you're talking about, food is exposed to ionizing radiation. The ionizing radiation can be from gamma rays produced by radioactive materials like cobalt-60. Or the ionizing radiation can be generated from using electricity to produce X-rays or electron beams. Electron beams are produced by linear accelerators. Because of its high energy level, ionizing radiation can knock electrons out of molecular orbits, which then slam into other molecules, dislodge more electrons, form new molecules, dislodge more electrons, and so on.

Gamma radiation is often preferred by food irradiators because it can penetrate deeply, and using a radioactive material to irradiate is cheaper. Electron beams penetrate food to a depth of only one-and-a-half inches, which means that linear accelerators are only useful for irradiating thin foods like hamburgers. X-rays can also penetrate deeply, but this technology is much more expensive to use because of the large amounts of electricity that are necessary.

Other forms of ionizing radiation include cosmic rays and higher-frequency ultraviolet rays. Because they are emitted from the nuclei of radioactive isotopes, gamma rays, the type of radiation created by radioactive materials like cobalt-60, have the added ability to make other things radioactive.

Non-ionizing radiation includes visible light, infrared (heat), microwaves, and radio waves. This type of energy does not have sufficient energy to dislodge electrons.

The best example of how ionizing and non-ionizing radiation have vastly different effects is the human body. Ionizing radiation damages chromosomes by blowing apart DNA molecules, which can lead to leukemia and other cancers. In the case of chromosomes of sperm and egg cells, this can cause birth defects. Children of women exposed to ionizing radiation during pregnancy can be born with brain and eye abnormalities, skeleton defects, an abnormal number of fingers and toes, and failure to thrive.

Non-ionizing radiation, because of its lower energy level, can merely cause molecules to vibrate and heat up-again like microwaving leftovers. Electrons are not ripped out of their orbits. Chromosomes and DNA are not damaged.

No, the ionizing radiation used to "treat" food does not get passed on to people who eat irradiated foods.