Why cleaning your kitchen sponge only makes it dirtier

You will never look at your kitchen sponge the same way again.

The fact that the squishy, crayon-colored kitchen helper is actually a microbiological hot spot teeming with bacteria isn’t a huge surprise. It’s the perfect breeding ground for bacteria — warm and wet.

But a recent study in Scientific Reports by researchers at the University of Furtwangen in Germany shows that the number and kinds of bacteria are worse than previously thought.

The research team looked at the DNA and RNA in samples from 14 used sponges and found 362 different species of bacteria, including the kind that can cause infections in humans with weak immune systems. They concluded that about 82 billion bacteria were living in just one cubic inch of sponge space.

“That’s the same density of bacteria you can find in human stool samples,” microbiologist Markus Egert told the New York Times. “There are probably no other places on Earth with such high bacterial densities.”

And now we know that using the microwave as your go-to sponge-cleaning method may be making things worse. While the microwave trick may kill some bacteria, the strong ones will survive — and they can make you sick. The same applies to sponges tossed in the dishwasher, cooked in hot water, or soaked in vinegar.

In an interview with NYMag.com, Solveig Langsrud, a senior scientist at Nofima in Norway who studies microbial communities in food production and preparation, suggested using a kitchen brush, dish towels, paper towels, or a drying rack to help control bacteria in the kitchen.

For those who want to upcycle a kitchen sponge for use in the bathroom, Egert told the Times that they should run them through the laundry on the hottest setting with a powder detergent and bleach.

But when the sponge starts to really smell, it’s best to toss it out.

As for that sponge in your office kitchenette … don’t even go there.