The Microwave Oven as a Force for Good

Like many families on the “go” — I have learned to love my microwave oven. It boils my water, pops my popcorn. Nukes my hotdogs….and sterilizes the kitchen sponges.


That’s right. A recent study has shown that microwave ovens can be used to sterilize kitchen sponges.

Now why the heck didn’t I consider that before?

It’s obvious (well, as obvious as it can be for a kitchen sponge). After washing dishes and wiping down table tops, the simple kitchen sponge can soak up everything from fecal bacteria and viruses to parasites and bacterial spores.

A University of Florida ( team found that putting the wet sponge in the microwave for just two minutes at full power could kill a range of bacteria, viruses and parasites.

Yes! Take that you bacteria-vermin! The microwave oven as a force for good: the shelf-life of my kitchen sponges just got a little bit longer. And presumably my family and I will be a little healthier as a result.

Be warned, though, that if you do not soak the sponge before microwaving it, it will likely catch fire and possible ruin the microwave. The heated water also seems to help the sterilization process.

The University of Florida research team also warns consumers not to confuse sponges with a brillo pad. Because — as many of you hopefully know — sticking metal objects into a microwave makes for one heck of a fireworks display.

Researchers soaked sponges and scrubbers in a disgusting brew of raw wastewater containing fecal bacteria, viruses, protozoan parasites and bacterial spores, including Bacillus cereus spores – which are known for being very hard to kill with heat, chemicals and even radiation.

Zapping at the bacteria-infected sponges at full power for two minutes killed or inactivated 99 percent of living pathogens. It took 4 minutes to destroy the B. cereus spores. But they were eradicated and this is what counts.

The study was detailed in the December issue of the Journal of Environmental Health (

Other studies have shown that sponges and dishcloths are common carriers of pathogens from uncooked eggs, meat and other food. Damp objects help them thrive.

The researchers suggest wetting the objects — water being heated by the microwave seems to play a role in the sterilization — before zapping them every other day or so.

According to a re-cap of the study in, the survival of micro-organisms (heterotrophic plate counts, E. coli, and bacterial spores) was halted in a regular consumer-type microwave oven. Kitchen sponges, scrubbing pads, and syringes were experimentally contaminated with wastewater and subsequently exposed to microwave radiation. At 100 percent power level, it was found that the total bacterial count of the wastewater was reduced by more that 99 percent within 1 to 2 minutes, and the total coliform and E. coli were totally inactivated after 30 seconds of microwave radiation. Bacterial phage MS2 was totally inactivated within 1 to 2 minutes. Spores of Bacillus cereus were more resistant than the other microorganisms tested, and were completely eradicated only after 4-minute irradiation.

Pause for a second and consider that the typical sponge or kitchen rag is used over and over again and at the very least is rinsed out in warm water and re-used, but not specifically sterilized. Microwave zapping remedies that.

An article in Reuters ( recounts that similar sterilization rates were obtained in wastewater-contaminated scrubbing pads.

So now you know! There may be a lot of controversy about microwave ovens in general – some nutritionists feels that zapping food zaps away the vitamins as well — but this particular argument regarding sponge sterilization has no opposition.

Microwave sponges…get rid of bacteria…and be healthier because of it!

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