Microwave Safety Hazards

Liquids

• It is possible for liquids to "superheat" when they are heated in a microwave. This means that a liquid has reached a temperature above its boiling point without actually going through the boiling process, which involves releasing bubbles of vapor as the liquid gradually heats up to boiling point. In some cases when the liquid is removed from the microwave, the act of disturbing the water can cause spontaneous boiling, which can be powerful enough to launch the liquid out of the container, resulting in nasty burns for the person holding the container.

Metal

• Metal should never be put in a microwave. The metal object will act as a conduit to the current and become a heating element itself, which can be a serious fire hazard. Metallic papers such as foil or take-away containers can create sparks when they are microwaved, as can cutlery and other smaller metallic substances. An exception to this is in microwaves that are equipped with metal shelves; these shelves can be used for heating foods with metal wrapping, as they are specially designed to harness the current and improve the heating process.

Empty Microwave

• If a microwave is run without anything inside, it can cause the microwave to burn out. With nothing inside the microwave to absorb the radiation, the energy simply bounces back and forth between the cooking chamber and the magnetron tube (the tube that provides the cooking power).

Radiation

• It is extremely unlikely that a modern microwave will fall foul of radiation leaks, but it is something that concerns people when considering microwave hazards. The Website ccohs.ca states, "Old or faulty door seals are the most common causes of microwave radiation leakage." It is recommended to replace a microwave that displays signs of damaged doors or seals.

Fire

• Overcooking can cause food cooked in the microwave to catch fire, and although this is not unique to microwaves---almost all forms of cooking have some degree of fire risk---it is amplified by the speed in which things cook in the microwave and the contained nature of the cooking process. It is recommended to pay close attention during the whole cooking process.

Explosion

• If you place a sealed container or plastic in a microwave, there is a risk of explosion. This is due to the amount of pressurized steam that builds up inside the container unless it is relieved. This is why you will often find instructions telling you to fork holes in a container before you cook a microwaved dinner; if the pressure is not relieved, the whole container could explode.