In this Moment of Science, we discuss the safety of microwave ovens.
You may have heard rumors that microwaves can cause serious health problems when standing directly in front of one. Some have even said that microwave radiation can cause cataracts, immune problems, or even sterility. I’m happy to tell you that this notion is false.
Microwave ovens have been regulated by the FDA for 30 years, and I don’t think they’ve been proven to cause any health problems. While the window of the microwave lets light through, it can’t let the microwaves out.
Microwaves pass right through glass and plastic, but they are reflected by metal: that’s why you should never use metal in the microwave oven. Look closely at the glass window in the oven door: it’s covered by a metallic mesh screen. The metallic mesh keeps microwaves in but lets light out because microwaves are relatively huge compared to light waves.
Picture the large microwaves as a slinky, bouncing around in your microwave oven: the slinky isn’t about to fit through the little holes in the door. To the slinky, and to the microwaves, the mesh door might as well be solid metal since it will bounce them back into the chamber.
One thing to keep in mind, microwave ovens have two safety latches on the door, and the oven shouldn’t work if even one latch is broken. But, if the seal is very dirty or in poor repair, the oven could leak.