You may have seen tips and tricks on how to clean a dirty sponge, but a new study says that commonly used methods can actually increase harmful bacteria.
A team of microbiologists from the University of Furtwangen in Germany recently published a study on kitchen sponges and their bacterial contents.
Dirty sponges are as dirty as poop
Unsurprisingly, they found that dirty sponges are absolutely crawling with bacteria. A dirty sponge could contain as much as 82 billion bacteria in just a cubic inch of sponge.
"That's the same density of bacteria you can find in human stool samples," Dr. Markus Egert told the New York Times. "There are probably no other places on earth with such high bacterial densities."
Most people already know that kitchen sponges are veritable havens for germs, but the surprising part of the study was that cleaning those sponges can sometimes make them even worse.
What happens when you clean a dirty sponge?
The study states that, of commercial products that claim to clean kitchen sponges, "No method alone seemed to be able to achieve a general bacterial reduction of more than about 60%"
Furthermore, the study determined that regularly cleaned sponges contain about the same amount of bacteria as uncleaned ones. How can that be?
The study explains that when you microwave or boil your sponge, it kills the weak and harmless bacteria, thereby making room for the resistant strains of bacteria to recolonize in the now empty space.
This is similar to how overusing antibiotics and hand sanitizer has encouraged the growth of resistant bacteria (also known as superbugs).
Several bacteria that were identified can cause infections in immunocompromised humans. Moraxella osloensis, for example, was one bacteria that was pinpointed by the study. Moraxella osloensis is the bacteria that makes dirty laundry stink.
So what do we do?
It's important to realize that bacteria are ubiquitous in our environment. Bacteria are always present in our bodies and on our skin. Even moraxella osloensis is commonly found on human skin.
Some kinds of bacteria are even beneficial. Lactobacilli, for example, aids the digestive process.
Even the widely publicized and highly feared MRSA bacteria lives inside the human nose. So there's no cause for panic, but this is why proper hygiene and cleanliness are so important.
So should you toss out your kitchen sponges? For the most part, yes, especially if they're dirty enough to smell. However, if you are determined to keep them, Egert recommends washing them in the washing machine on the hottest setting, and using powder laundry detergent in conjunction with bleach, after which they should be used in places where no food is prepared (like the bathroom) rather than the kitchen.