Change in your DNA, called "mutation," can happen on its own when the body makes copies of DNA so that the cell can divide and still keep a complete set. However, certain things make mutations happen more often.Radiation is one of those things. Think about a ship being hit by cannon balls. The DNA is like the ship and the radioactive particles are like the cannon balls, except that it's all happening at a level too small to be seen directly, even with our best microscopes.

Microwave ovens use radiation to push around the water molecules in food. Heat is just movement of molecules, so this is what heats the food. As long as the shielding in the microwave oven does its job, the radiation doesn't leak out to cause mutations. Of course, it's possible that the shielding is broken or was never made right to begin with. If you trust the regulation of microwave manufacturing, then you shouldn't worry about mutation, but it wouldn't hurt to stay a meter or so away,just in case.

Why is mutation a problem? Which do you think is worse, mutation in askin cell, or mutation in a cell that can become an egg or sperm?

Microwaves themselves don't have much effect on DNA.But they can heat the water in your skin, and heat can damage DNA--just like any other burn. The myth of DNA damage is usually spread when people get confused about the difference between *electromagnetic* radiation (like light or radio waves) and *ionizing* radiation. Ionizing radiation mostly comes from radioactive sources. Several kinds of ionizing radiation will cause DNA damage. But microwave ovens are not radioactive, and they do not cause ionizing radiation. Another myth about microwaves is that they penetrate to the bone. Actually, microwaves are 99% absorbed in the outer 1cm of your body, and you would quickly feel the heat produced. Very little microwave energy gets below your skin. (Your eyes would be an exception. But you already know not to stand in front of a working microwave which has its door open.) The most important safety feature of a microwave oven is the door. Don't use one that doesn't close tightly.

Microwaves cause molecules with electric dipoles (like water) to rotate. The friction that this generates with the other molecules creates heat. DNA is an electrically charged molecule, so microwaving it will shake it up. If it gets damaged by the shaking, then you've mutated it.