Q. I know the kitchen sponge grows bacteria. I have been putting it in the microwave for 30 seconds with the expectation that zapping it will kill the bacteria. Do you think this is effective?
A. Several years ago we found an article in the Journal of Environmental Health (Dec. 2006) that suggested wetting a sponge and nuking it in the microwave for one to two minutes at 1100 watts of energy to kill lingering germs.
One reader who tried this reported: “We microwaved our WET sponge this morning and it caught on fire. Now our house smells terrible. It was scary and annoying at 6:30 am!”
Scientists have published on the pros and cons of using microwave disinfection for dentures (Journal of the American Dental Association, March 2012) and toothbrushes (American Journal of Dentistry, June, 2011). Toothbrushes are best disinfected by soaking in Crest Pro-Health mouthwash for 20 minutes or by running them through a normal dishwasher cycle. For dentures, microwave treatment for three minutes at 650 watts was effective, as was a 10 minute soak in chlorhexidine solution (e.g., Peridex).
We have not seen a comparative study for kitchen sponges, but running the sponge through a regular dishwasher cycle might be a good approach for disinfecting it, as well.