Verdict: False. The FDA says microwave energy does not make food "radioactive" or "contaminated," and the EPA says the same; microwaves heat food by making its water molecules vibrate.
Where the idea comes from
The word "radiation" carries a lot of weight. It's used for X-rays and nuclear material as well as for microwaves, light and radio, so "microwave radiation" sounds as if it must leave something behind in the food. The nickname "nuking" food doesn't help. A related belief holds that microwaving strips nutrients out of food.
What the evidence says
The FDA's page on microwave ovens explains that microwaves cause water molecules in food to vibrate, producing the heat that cooks it, and that this energy does not make food "radioactive" or "contaminated." It also notes a federal standard that limits how much microwave energy can leak from an oven throughout its lifetime, to 5 milliwatts per square centimeter at about 2 inches from the surface.
The EPA's RadTown page on non-ionizing radiation used in microwave ovens is just as direct: "Microwaves do not make food radioactive." It explains that the oven's radiation exists only while it's operating and is absorbed by the food. The EPA adds that most microwave injuries are burns from overheated food or liquids.
On nutrients, an article on the Health Physics Society's website, written by a certified medical physicist, says that "microwave cooking does not reduce the nutritional value of foods any more than conventional cooking."
What to do instead
- Use your microwave normally; the food isn't changed by the method in the way the myth suggests.
- Focus on the real hazard: burns. Open covered dishes away from your face, and let liquids stand briefly.
- Use only containers labeled microwave-safe.
- Keep the door, its seal area and the cavity clean so the door closes properly.
- Follow the manufacturer's instructions for your model, as the EPA advises.
Exceptions worth knowing
- •A damaged door is a real concern. The FDA says not to operate a microwave if the door doesn't close firmly or is bent, warped or otherwise damaged. The EPA says the same about a door that won't shut or seal well.
- •Don't lean on a running microwave. The EPA advises not standing directly against the oven while it operates.
- •A microwave that runs with the door open should be unplugged and not used again until it's repaired.
- •Weaker heating isn't a radiation issue. See whether microwaves lose power as they get older.
Sources
- •FDA: Microwave Ovens (not radioactive; leakage standard; damaged doors)
- •EPA RadTown: Non-Ionizing Radiation Used in Microwave Ovens (not radioactive; burns; standing against the oven)
- •Health Physics Society: Microwave Ovens (nutritional value)
The short version: Microwaved food isn't radioactive; the door and hot liquids are what deserve your attention.
Bent door, a latch that won't catch, or an oven that keeps running with the door open: unplug it, leave it unplugged, and call TrueFix Los Angeles at (213) 787-3989 for microwave repair.