Zapping sponges may have unexpected results

The reports last week stating that zapping sponges in a microwave oven can kill most household germs no doubt were welcome news for those who fear what might lurk in their kitchen sponge. But take them with a grain of salt, or at least a healthy dose of caution. The reports, based on a recent University of Florida study, stated that a sponge tossed into a microwave will shed most of its germs within two minutes of cooking, with the rest gone after between four and 10 minutes. "Consumers ... can use microwave ovens to significantly reduce microbial pathogens in the home environment," wrote the authors in an article that appeared recently in the Journal of Environmental Health (JEH).

While microwaving wet sponges to sterilize them has been practiced for a number of years — the JEH ran a similar report back in 1999 — some of the nuance was apparently lost in translation (and in most news reports). Overeager consumers who tried to repeat the experiment at home found themselves trading microbes for smoke. According to Reuters, a number of consumers tried to clean dry sponges in their microwaves, resulting in smoke, flames, and ruined microwaves. After microwaving a sponge, "our entire house stinks like a burning tire for several hours," one commenter told the news service. The university has issued a clarification stating that "to guard against the risk of fire, people who wish to sterilize their sponges at home must ensure the sponge is completely wet."

We have a better idea:  Clean the sponge with the dishes the dishwasher, placing it in the covered part of the utility basket so it won't fall onto the heating element. Models that meet requirements for the NSF mark (left) are certified to get hot enough for long enough to kill bacteria, at least on the sanitize cycle. Or use wet paper towels and soap to clean up spills and countertops after working with especially risky foods like raw chicken and ground beef. Toss them in the trash and wash your hands when you're through and you'll be reducing your risk of cross contamination in the kitchen, with no risk of smoke and fire.