First, we need to understand how it works.
To understand why these claims are so ludicrous, you first need to understand how microwave ovens work. When you push the “Start” button on your microwave oven, tiny, energetic waves start moving through the inside compartment of your oven, passing through everything in the compartment. These waves, called microwaves, are a type of electromagnetic radiation. The waves vibrate rapidly, at about 2,500 megahertz (2.5 gigahertz) a minute. That’s about the same frequency as your cell phone.
A little clarification about the word “radiation” is in order here. Microwaves radiate – just like waves in a pool of water radiate outward if you drop a rock in a pool of water. But they are a type of non-ionizing radiation, unlike potentially harmful ionizing radiation. Ions are charged particles that split off from a molecule. Microwaves and other typed of non-ionizing radiation have enough energy to cause atoms in a molecule to move or vibrate, but not enough to remove particles. Sound waves, visible light, and microwaves fall in this category. Ionizing radiation, however, has enough energy to kick off electrons from atoms – creating ions. Examples of ionizing radiation include ultraviolet light from the sun, x-rays, and gamma rays.
As those microwaves vibrate, they are absorbed by any water present in the oven. The energy in the waves causes water to vibrate quickly. This is because of a special characteristic of water: it has a positive and negative end (remember your high school chemistry? Hydrogen carries a plus-1 charge, and oxygen a minus-2). In other words, it is a dipole. As the water molecules vibrate, the friction between them creates heat. In turn, the heat cooks the food.
All food contains some water, so when microwaves travel through food, it heats quickly. Most plastics, glass, paper, and ceramics are unaltered by microwaves. Metals, however, reflect microwaves. That’s why metal pans and aluminum foil should not be used in microwave ovens.
Microwaves do not cook food from the inside out (another microwave myth). Microwaves are absorbed in the outer layers of food, in much the same way as in conventional cooking methods. The heat from outer layers of the food actually cooks the innermost areas
HARMFUL EFFECTS :
We have a love-hate relationship with our microwave ovens. About 90 percent of us own one; they’re ubiquitous in restaurants, coffee shops, airports, even corner convenience stores. But we’re also nervous about those little black (silver, red, grey….) boxes that haunt our kitchen countertops.
Stories detailing the dangers of microwaved food permeate the internet. Yet it takes only a quick skim and a smattering of scientific literacy to see that most of the claims made in those stories are based on poor science, rumors, fear-mongering, and conspiracy theory. Some of my personal favorite myths:
Microwaved food, when consumed continuously over a long period, “shorts out” electrical impulses in the brain, depolarizing or de-magnetizing brain tissue.
Reality check: Search after the search of PubMed, the Cochrane Library, and CINAHL turned up no research supporting this claim.
Microwaving food changes its chemical composition in some mysterious, unknown way, destroying the “vital energy” and nutrients in food.
Reality check: As far as changing the chemical composition of food… um, what happens to it when you bake, broil, sauté, or otherwise apply heat to it? And microwaving food generally preserves more nutrients, mostly because the cooking time is shorter and the food can be cooked in less water.
Microwaving water cause changes in its “structure or energy.” This one started out as one of those widely-circulated emails that described somebody’s granddaughter’s science fair experiment. One plant was watered with water that had been boiled on a stovetop, the other with water that had been boiled in the microwave. The accompanying photos supposedly show the gradual demise of the plant watered with the microwaved water.
Reality check: As an experiment, the two-plant scenario wouldn’t pass muster for an elementary school science fair project. Barbara Mikkelson over at Rumor has it offers an explanation of the scientific method – for those of you who slept through junior high science class – and debunks this myth solidly. She also ended up with several very healthy-looking plants.
Microwaving food or water causes the formation of “radiolytic compounds” — new chemicals created by the tearing apart of molecules. Depending on the version of the microwave myth, these chemicals are said to be cancerous, radioactive, unnatural, or otherwise dangerous.
Reality check: Microwaves do not have enough energy to “tear apart” molecules. Microwaves are simply electromagnetic waves – they have nothing to do with radioactivity.
Male and female hormone production is shut down and/or altered by continually eating microwaved foods.
Reality check: A search of PubMed, Cochrane, and CINAHL turned up no results in peer-reviewed journals.
If any of these (or several other equally off-the-wall stories) were true, it would be a miracle that anyone is alive, thinking, and reproducing. Consider that microwave ovens have been used for more than 50 years – in our homes, restaurants, laboratories, and more.
No valid, peer-reviewed research has ever documented that microwaving food or water causes any of these ill-effects.
Is food cooked in a microwave oven bad for your health?
First, we need to understand how it works.