I really enjoy listening to “Risky or Not”. This is a short podcast produced by two
Extension Food Safety Specialists, our own Dr. Ben Chapman from NCSU Cooperative Extension and Dr. Don Schaffner from Rutgers in New Jersey. In each episode the professors address everyday risks from germs. It’s usually a food safety or health related question that has been asked by a listener. They look at research and science and give their rational for deciding if it is risky or not.

On one of their recent episodes a listener asked about the risks of microwaving kitchen sponges. The professors looked at this question two different ways. First is it really safe to put a sponge in the microwave. Then they also looked at why people would want to put a sponge in the microwave in the first place. Overall, they determined that microwaving kitchen sponges isn’t risky. They also said that not microwaving kitchen sponges is also not risky.

The safety question. It could be risky to put a sponge in the microwave if you put it in
dry as it may cause a fire inside the microwave. There is also a risk of getting burnt if a water-filled sponge is heated too long. Dr. Chapman’s favorite sponge (yes, he does use a kitchen sponge) has steel wool in it which might cause microwave arching or sparking.

So, you still have to take some care even with a not risky verdict.

Many people microwave their kitchen sponges in an effort to destroy potential
foodborne pathogens that may be lingering in the sponge. The listener had sent in an
article from the internet that said microwaving sponges may not be achieving this goal.

Foodborne pathogens can live in a kitchen environment. Sponges hold food particles
and water making them a great place for bacteria to grow. However, both professors
agree kitchen sponges are not a significant cause of foodborne illness.
They discussed a study that was published in Science Direct that was looking for a
simple, fast and effective method for disinfecting kitchen sponges. They experimented by soaking sponges in bleach, lemon juice and deionized water and putting in the microwave and the dishwasher. Both the microwaving and dishwashing treatments lowered the bacterial count, more than the chemical treatments.
While that sounded like a good answer, Drs. Chapman and Schaffner cautioned that
microwaving sponges has may variables. The amount of water in the sponge, the size of the sponge, how long you leave it and the wattage of the microwave may alter the effectiveness of this treatment for pathogen destruction.

So, what do the professors recommend? Since moisture is a major contributor to
pathogen growth, squeeze as much moisture out of your kitchen sponges as possible and allow them to dry out. Dr. Chapman throws his in the laundry a couple times a week—not because of his concern for pathogens but to prevent them from smelling.

Replace your sponge often. If you’re really interested in this topic the podcast may be worth a listen for the details.

Microwaving Your Kitchen Sponges is episode #792. It can be found at Riskyornot.co
(yes, that is co not com).

Resources

riskyornot.co - Microwaving Your Kitchen Sponges

riskyornot.co - Dried Chicken Juice Sponge

Syracuse is a Family and Consumer Science team member and can be reached at N.C. Cooperative Extension, Brunswick County Center 910-253-2610 or by email at clsyracu@ncsu.edu