Dear Radiating,

The radiation emitted from a microwave, radio frequency (RF), is set and monitored by the U.S. Food and Drug Administration (FDA) for a standard that is said to be acceptable and safe in the home. The radiation itself is "non-ionizing" — less harmful than the radiation of X-rays. RF exposure from a home microwave does not pose any risks as long as the safety mechanisms are in good working condition and that the microwave has a switch that automatically turns it off when the door is opened. There is the potential of leakage if the seal is cracked or caked with food, if the oven has been dropped, or if a fire has occurred inside. In any of these cases, you should bring your microwave in for repair, or purchase a new one. If your microwave is in good working order and you want to be extra safe, standing four feet away from the oven dramatically reduces radiation exposure — to just 1/100th of the maximum amount considered safe.

However, there is a very real danger of serious burns from hot containers, overheated foods, and injury from exploding foods. The main precaution to take after heating milk in the microwave for babies is to be sure that there are no "hot spots." "Hot spots" are developed because microwaves heat foods unevenly, where some sections are much hotter than others. When the milk is checked for heat level, it may feel fine, although there may be some portions that are burning hot. It is recommended that you shake the milk bottle, or liquid container, and let it stand for thirty seconds before checking the temperature. Other sources (the journal Environmental Nutrition) suggest not using the microwave to heat infant foods — either bottles of formula or baby food — because the uneven heat can cause a baby's mouth to be seriously burned.

According to the FDA, there is no additional damage to milk proteins or sugars when heated with a microwave rather than conventional oven or stove. In general, microwaves cook food faster and destroy fewer vitamins than conventional cooking methods. You may have read about recent research that shows a possible loss of human milk's immunologic qualities after microwaving, but further studies are necessary to support this. If you're really concerned, you can heat milk the old-fashioned way.

If you do use the microwave, here are a few tips:

• Prick cooking pouches and foods that have tight skins (e.g., tomatoes, hot dogs) to release steam as they cook.
• Never cook eggs in the shell. If you crack an egg open to cook in the microwave, be sure to prick the yolk before cooking.
• Remove lids or caps from containers, and cover with microwaveable plastic wrap (don't let it touch food), waxed paper, or parchment paper for cooking.
• Never turn on an empty microwave. Try keeping a glass of water or a box of baking soda in the oven just in case.
• Regularly clean the inside, the door, and the seal with a mild detergent and water.
• Never operate the oven when something is caught in the door.
• Remove metal twist ties from bags. They act as antennae and can cause a fire.
• Never use brown paper bags for popping popcorn. They can catch fire, too.

(Tips excerpted from Environmental Nutrition, May 1994)

Alice

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