In the summer of 2018, I moved into my first apartment that didn't have a dishwasher. Until that moment, I hadn't truly appreciated how wonderful it is to be able to give your dishes a good rinse and then just plop them into the dishwasher to emerge squeaky clean in an hour or so. Now that I'm getting close and personal with each pot and pan and washing them all myself, I can't help but get a little grossed out. How often should you replace your sponge? Because, although I try not to think about it, I'm sure that the little guys pick up germs like nobody's business.
Unfortunately, my sneaking suspicion about how yucky sponges actually are appears to be correct. A study published in the natural sciences journal Scientific Reports got into the actual dirty (get it?) details of what kinds of creepy crawlies could be all over your kitchen sponge, and not only did researchers discover that sponges are full of more bacteria than previously thought, but that bacteria is also super hard to get rid of. My mom has always run her sponges through the dishwasher to clean them, and I've tried microwaving mine in an attempt to give them new lives, but this study shows that none of the traditional sponge-cleaning methods are very effective in getting them clean. Instead, the researchers suggested replacing them on a weekly basis.
How dirty is dirty, though? Well, to put things in perspective a little, back in 2017, Markus Egert, a microbiologist at the University of Furtwangen in Germany, discovered 362 species of bacteria on living on sponges. “That’s the same density of bacteria you can find in human stool samples,” he told The New York Times. “There are probably no other places on earth with such high bacterial densities.”
What's worse, apparently this kind of bacteria isn't always that harmless. "Kitchen sponges not only act as reservoir of microorganisms," explained the researchers in the Scientific Reports study, "but also as disseminators over domestic surfaces, which can lead to cross–contamination of hands and food, which is considered a main cause of food–borne disease." Lovely.
Just take a moment to think about the fact that you probably use the same sponge to clean that cutting board you use to cut raw meat as you do to scrub down a pot you cooked quinoa in. Not to mention the idea that, unless you use gloves whenever you handle your sponge, all of those germs get right onto your hands.
The pathogens that the researchers found in the Scientific Reports study were rarely ones that your mess with your stomach like salmonella, but germs that could cause respiratory and blood-borne infections were plentiful, as per the study's findings. The most prevalent species found, from the genus Acinetobacter, could even lead to pneumonia or a blood infection called sepsis. Definitely worth adding new sponges to your weekly grocery list, if you ask me.
Using a washable dish cloth for some tasks is also a potential solution if you feel like throwing away a sponge each week is a waste. “Most bacteria can’t tolerate drying. They die during the drying process, so if you don’t want to use disinfectants, we think that drying can be just as effective," Solveig Langsrud, a senior scientist at Nofima in Norway who studies microbial communities in food production and preparation, told NYMag's The Strategist. "About 99 percent of bacteria can be killed simply by hanging anything out to dry.”