April 29, 2004 -- Researchers warn against microwaving eggs in the shell after treating a 9-year-old girl for severe eye trauma from an exploding egg.
When an egg is heated in the microwave, pressure builds up inside. This can occur with an intact shell as well as with egg yolks with open shells and even pierced yolks, according to the researchers.
In their report Saurabh Goyal from Queen Mary's Hospital in the U.K. and colleagues write about a 9-year-old girl who reheated a previously boiled egg (with an intact shell) in the microwave on full power for 40 seconds. She removed the egg from the microwave, placed it in a bowl, and 30 seconds later, the egg exploded while she was carrying it to the table. Part of the egg hit her right eye and face.
Parts of the egg pierced her cornea, the transparent covering that lies over the pupil and iris (the colored part of the eye), and ruptured her lens, the disc-shaped structure that lies just behind the pupil. After the injury, she could see only hand movements with her right eye.
The girl underwent surgery to repair her cornea. Three months later her lens was replaced with an artificial lens similar to how cataract surgery is performed. Her vision then returned to normal.
The researchers say that the instruction manual that comes with microwaves includes a warning against heating eggs with an intact shell. Manufacturers recommend multiple piercing before cooking or heating eggs, even those already boiled.
But the researchers say, in light of these findings and the potential seriousness of injuries from exploding eggs, warning should be more obvious -- possibly displayed on the microwave itself.
Safety Notes When Operating a Microwave
When used correctly microwaves ovens are safe. However there are some tips when considering the proper and safe use of microwaves to avoid injury. According to the National Institutes of Environmental Health Science:
- Do not operate an oven if it is damaged. The oven door must close properly and there should be no damage to the door seals and sealing surfaces, hinges, and latches.
- Do not use aluminum foil at anytime during the heating cycle. Metal utensils and utensils with metallic trim should not be used in the microwave oven.
- Avoid heating materials in cylindrical-shaped containers. Liquids heated in certain shaped containers (especially cylindrical-shaped containers) may become overheated. When overheated, liquids may splatter during or after the heating cycle resulting in possible injury.
- When heating liquids in screw-cap bottles, completely loosen the screw-caps to prevent pressure build-up within the container. This pressure build-up with a cap that is not sufficiently loose can cause the bottle to explode.
And one final safety note: Be careful when removing containers from the microwave. Some containers absorb heat and may be very hot. Use protective gloves to minimize any possible injuries.
SOURCE: Goyal, S.British Medical Journal, May 1, 2004; vol 328: pp 1075. National Institute of Environmental Health Science.