UNDATED (WEBMD) -- Germs may be lurking where you least expect them, according to a new study by NSF International.
Contrary to public perception that the bathroom is the most germ-ridden room in the house, the real trouble spot is the kitchen. And the most germ-tainted item is the one most people reach for when it's time to clean up: the sponge.
NSF International is a not-for-profit organization established in 1944 to certify and write safety standards for, among other things, common household items. It conducted a two-part study to determine where people think most germs reside and where those germs actually are.
The researchers recruited members of 22 different households who allowed NSF microbiologists to test 30 everyday items in their homes for a variety of bacteria, yeast, and mold.
Before they began their tests, the researchers asked one member of each household to answer survey questions to learn which items they believe harbor the most germs. Most of the volunteers pointed their fingers at the toothbrush holder, when in fact it was the kitchen sponge. Overall, the volunteers' perceptions of what's clean and what isn't did not square with reality.
And the reality is kind of gross. One group of bacteria the researchers swabbed for was coliform. Not only does the coliform family include salmonella and E. coli, common causes of food poisoning, but it often heralds the presence of fecal contamination. And a lot of it was found in the kitchen.
Coliform, which was found in 81% of the homes, commonly comes from raw meat and produce, as well as unwashed produce and unwashed hands.
According to the NSF International report, 77% of sponges and dish rags tested positive for coliform. Nearly half of the kitchen sinks they swabbed harbored the same nasty bacteria, while countertops and cutting boards came in third and fourth, with 32% and 18%, respectively, testing positive.
Meanwhile, bathrooms were much cleaner by comparison, though they, too, could stand a good scrubbing. Twenty-seven percent of toothbrush holders had traces of coliform bacteria, while 9% of faucet handles showed similar contamination.
"Sponges pick up bacteria during the cleaning process and are typically not properly -- or regularly -- sanitized before their next use," study researcher Rob Donofrio, director of Microbiology at NSF International, says in a news release. "They also have many nooks and crannies which can be great places for germs to multiply."
Toothbrush holders, due to their close proximity to toilets, pick up bacteria that swirl through the air after the toilet is flushed. And they are often frequently overlooked when cleaning the bathroom, according to Donofrio. That's odd, considering that the study participants ranked toothbrush holders as the place most likely to harbor germs. It's actually the third dirtiest item in the house.
Yeast/mold and staph bacteria were found in 31.7% and 6.4% of homes, respectively. Sponges were the most common harbors for yeast and mold. But in nearly 60% of the houses tested, yeast and mold were also found on video game controllers and remote controls. Staph bacteria turned up on nearly a quarter of the pet toys tested.
"We conducted this study to help identify where the germs are in the average person's home and -- more importantly -- help people understand how they can better protect themselves from bacteria, yeast, and mold," Donofrio says.