Many of us have heard the horror stories of the bacteria contained in ordinary kitchen sponges and that it may be equal to or higher than bacteria found on toilets. This is disturbing enough, but the key is figuring out what to do about it. You may decide to continue using the sponges using the recommended techniques below or swap out in favor of other alternatives such as a plastic scrub brush.
The study, published in Scientific Reports, undertook a thorough investigation into how many critters are living in used kitchen sponges. And the results were jawdropping.
"We found 362 different species of bacteria, and locally, the density of bacteria reached up to 45 billion per square centimeter," says Markus Egert, a microbiologist at Furtwangen University in Germany, who led the study.
Forty-five billion microbes per square centimeter? Are you kidding? If you scale that up, that's like stuffing all the people who live in Manhattan into the Rockefeller ice rink.
"That's a very huge number of bacteria, indeed," Egert tells NPR. "There's hardly any habitat on Earth where you'll find similar densities of bacteria, except for the human intestinal tract."
In other words, there can be spots on your kitchen sponge with just as high concentrations of bacteria as in a toilet.
- Keep the sponge away from raw meat. "If you're dealing with raw juices from meat or poultry, you should be using paper that can be disposed of," Quinlan says.
- Don't keep sponges around for too long. "I replace mine every one to two weeks," she says. "That's reasonable to me."
- Clean the sponge every few days. The USDA recommends putting it in the dishwasher with a heated dry cycle, or wetting the sponge and popping it in the microwave for a minute.
Microwaving the sponge will knock down the bacteria living in it by about a million-fold, scientists at the U.S. Department of Agriculture reported back in 2009. Of course, this method will leave many still alive since there are billions in the sponge. But the heat targets the dangerous ones, Quinlan says.