Microwave ovens are provided in all residence units either as a counter appliance, mounted under kitchen cabinets, or attached to a micro refrigerator.  Most students are familiar with the use of microwaves.  Typically the user selects the level of heat and desired length of cooking time before starting the unit.  Microwave ovens are frequently used for reheating previously cooked food.  Microwave ovens heat food without getting hot themselves.  The radiation produced by microwave ovens is not harmful because it is non-ionizing. As such, it does not have the specific cancer risks associated with ionizing radiation such as X-rays, ultraviolet light, and high-energy particles.  A microwave is a convenient cooking appliance, but users need to be conscious of necessary precautions. 
 

Food in microwave ovens often cooks unevenly:

Uneven heating in microwaved food is partly due to the uneven distribution of microwave energy inside the oven, and partly due to the different rates of energy absorption in different parts of the food.  Bacterial contamination may not be killed if the safe temperature is not reached, resulting in possible exposure to foodborne illness.  Uneven heating of frozen foods is a particular problem, since ice absorbs microwave energy much less well than liquid water, leading to defrosted sections of food warming faster.  In baked goods containing berries, the berries absorb more energy than the drier surrounding bread and the result is frequently the overheating of the berries relative to the rest of the food.

The microwave can be periodically stopped and food stirred/turned during heating to address these problems. If the oven has a turntable or carousel that turns the food, place food or its container a bit off-center so that the item travels all around the area of oven's cooking cavity, thus achieving more even heating.  Cooking food at a lower power setting and for a longer period can usually address these issues.

Food cooked in containers, wrapped or raw requires caution:

Cookware used in a microwave oven is often much cooler than the food because the microwaves heat the food directly and the cookware is heated by the food.  Some liquids, when heated in a microwave oven in a container with a smooth surface, can superheat; that is, reach temperatures that are a few degrees in temperature above their normal boiling point, without actually boiling. The boiling process can start explosively when the liquid is disturbed, and can then result in liquid and steam burns.  Closed containers, and food like eggs and whole potatoes in their skins, can explode when heated in a microwave oven due to the pressure build-up of steam. 

Closed containers need to be ajar, and wrapped food slightly exposed, when heated in a microwave to dissipated steam.  Potatoes or other vegetables with thick exteriors need to be pierced with a fork for the same reason.  Eggs should not be cooked in their shells.  Precaution should be taken to avoid any burns by using a potholder to remove food or beverage from a microwave oven. 

Metal objects should not be used in microwaves:

Any metal or conductive object placed into a microwave will act as an antenna to some degree, resulting in an electric current, causing the object to act as a heating element.  Any object containing pointed metal, like a fork, can create an electric arc (cause sparks) when microwaved. This includes cutlery, aluminum foil, ceramics decorated with metal, and most anything containing any type of metal.  Fire can occur when a Chinese takeout box with a metal handle is heated in a microwave. Twist ties containing metal wire and paper are also notoriously dangerous.

Common sense dictates that a user is careful, and does not leave a microwave unattended when heating anything unfamiliar. If a spark is observed, immediately open the door to cut the power.