What Are the Dangers of Cooking With Microwave Ovens?

Superheated Liquids

• Roiling bubbles in a liquid, such as water or coffee, are a visual indicator that the liquid has reached a boiling point. However, liquids heated in a container with a smooth surface can reach a boiling point without bubbles or vapor. The danger comes when the liquid is disturbed by either movement or the addition of a solid ingredient. The most common occurrence of this problem is heating water to make tea. Once the tea bag is added, the water can react with spontaneous boiling. Known as nucleation, the reaction can be violent enough to eject the liquid and cause severe scalding.

Arcing Metals

• Metals should never be put in a microwave. The arcing comes from a dielectric breakdown of air which forms near metals as a conductive plasma. Visible as a spark, the danger is greater than the obvious fire risk. Dielectric breakdown creates ozone and nitrogen oxide, both of which are unhealthy to inhale.

Plastic Leaching

• Heating food in plastic containers, especially those containing polyvinyl chloride, polycarbonate and plasticizers may present a possible health risk. According to the Mindfully.org, plasticizers, a term for chemicals that make plastic soft and pliable, may migrate into food cooked at high temperatures. While it has not been determined how much risk is involved with low-level exposure to chemicals in plastics, the FDA recommends cooking in microwavable glass or ceramic dishes. Plastics that are microwave safe will be clearly identified.

Beryllium Oxide Exposure

• Some microwaves have ceramic insulators which contain beryllium oxide (known as beryllia). Dangerous if crushed or ingested, or even if the dust is inhaled, at no time should a broken ceramic insulator be handled. Generally not a problem, damage to the insulators can occur if the unit is dropped or damaged by force. Severely damaged microwaves should be disposed of according to local laws. Most communities hold hazardous waste roundups several times a year.