Everyday Q & A: Is it safe to sit in front of the microwave?

Jonathan Hwang | jonathan.hwang@yale.edu December 11, 2007

In culinary spheres, a microwave oven is frowned upon. Nevertheless, it has become an integral part of the kitchen. Owing to the fact that its function is based on a form of electromagnetic radiation, concerns about its possible health hazards have continually arisen.

Due to their relatively low frequency (below that of visible light), microwaves transfer energy insufficient to cause ionization and direct chemical change of substances. Studies carried out to elucidate the health effects have been inconclusive: some show that it can potentially pose health hazards, while others contend that it is absolutely safe.

In fact, the most dangerous aspects of the microwave are related to over-heating rather than to any mutagenic potential. According to the U.S. Food and Drug Administration, exposure to high levels of microwave radiation can cause painful burns. For instance, radiation can cause cataracts in heat-sensitive eye lens and kill sperm, leading to temporary sterility.

However, even these effects require radiation levels much higher than the total amount an average person will be exposed to throughout life. Regarding the effects of chronic exposure to low levels of microwave radiation, little evidence exists and for this reason the FDA requires that all reasonable safety precautions as described by the manufacturers be enforced.

Suggestion: instead of sitting in front of the microwave and pondering the effects of its radiation, you could invest your time on measuring experimentally the speed of light. Remove the turntable and place on it a casserole dish covered with marshmallows. Heat them with low heat until they start melting at different spots.

A stationary wave is formed in the microwave, which causes melting at the points where the wave has its maximum amplitude (every one half of the wavelength). By multiplying the distance between the melted spots (around 6 cm) by two, and then multiplying the frequency of the wave (around 2450MHz) you get a number fairly close to the speed of light.