608. Does cooking in a microwave oven destroy the nutritional value of foods? Are microwaves radioactive? Does radiation "leak" from the oven? - DL
Microwaves are essentially high frequency radio waves. They heat food by twisting its water molecules back and forth so that those water molecules rub against one another. Like all electromagnetic waves, microwaves are absorbed and emitted as particles or "photons," but the photons of microwaves have so little energy that they are unable to cause chemical changes in the molecules they encounter. They simply heat food; they don't "irradiate" it. The only way a microwave oven damages the nutritional value of foods is if it overheats. Microwaves are not radioactive—radioactivity is the spontaneous fragmentation of the nuclei of atoms and is usually associated with the emission of high-energy particles; particles that can induce chemical changes in the molecules they encounter. Finally, if a microwave oven was properly constructed and hasn't been damaged, virtually no microwaves leak from it. A small amount of microwaves won't hurt you anyway—they are present all around us already because of satellite transmissions, cellular telephones, and even the thermal radiation from our surroundings.