Microwave urban legend shouldn't obscure real risks
A reader recently forwarded us an email that he felt was important enough for us to publicize. Here it is:
"A 26-year old decided to have a cup of coffee. He took a cup of water and put it in the microwave to heat it up. (Something that he had done numerous times before). I am not sure how long he set the timer for, but he told me he wanted to bring the water to a boil. When the timer shut the oven off, he removed the cup from the oven. As he looked into the cup, he noted that the water was not boiling, but instantly the water in the cup 'blew up' into his face. The cup remained intact until he threw it out of his hand but all the water had flown out into his face due to the build up of energy. His whole face is blistered and he has 1st and 2nd degree burns to his face, which may leave scarring. He also may have lost partial sight in his left eye. ..."
On investigation, we discovered that the reader had never met the 26-year-old burn victim. It was simply a story making the rounds on the Internet, almost identical to one that’s been around for several years, according to Snopes.com, the tracker of urban legends.
However, that doesn’t mean that we should immediately discard this email as worthless. It does remind us about safe microwave use. According to Consumer Product Safety Commission data, about 4,000 Americans incur injuries from microwaves every year. Almost a third of these injuries are burns and scalds. So while it may seem like a no-brainer to boil that cup of water in the microwave, think again. According to the Food and Drug Administration and the Association of Home Appliance Manufacturers, over-heating water in a cup can result in superheated water -- or water heated past its boiling temperature. The water does not appear to be boiling, because the air bubbles that trigger boiling have been expelled. The liquid is just waiting to boil. A speck of dust or a tiny air bubble caused by movement or a slight vibration can initiate vigorous boiling and occasionally cause a violent eruption.
The AHAM says consumers need to be particularly careful with tall cups and containers because the energy that builds as the temperature rises is forceful enough to eject the liquid. This phenomenon seems more likely if water is heated in a clean cup. The risk is reduced if foreign materials such as instant coffee or sugar are added before heating. AHAM advises consumers to stir liquids before heating them in the microwave to help prevent sudden boil overs. Also, do not heat liquid for more than 2 minutes (and considerably less time if you have less than a cup). After heating, allow the liquid to stand in the microwave for 30 seconds before moving it or putting anything into it.
Posted by: dt | Feb 18, 2007 6:45:45 PM
"...about 4,000 Americans incur injuries from microwaves every year. Almost a third of these injuries are burns and scalds."
Useful information, but it would be helpful to know the causes of the other two-thirds of microwave risks.