Sharing a space with multiple people is hard enough. Dirty dishes seem to multiply at an exponential rate, no one ever wants to vacuum and there’s always one roommate who’s a little short on the rent. Now, a study out of Quinnipiac University makes shared living much, much worse: If your tooth brush resides in a communal bathroom, there’s a good chance it’s covered in fecal bacteria – not just your own, but other people’s.
To clarify: If you share a bathroom, odds are you’re scrubbing your teeth with the stuff that comes out of your housemates’ butts.
“The main concern is not with the presence of your own fecal matter on your toothbrush, but rather when a toothbrush is contaminated with fecal matter from someone else, which contains bacteria, viruses or parasites that are not part of your normal flora,” said Lauren Aber, MHS, a graduate student at Quinnipiac University.
The study involved communal bathrooms that averaged 9.4 shared users, so this is more of a dormitory situation than a shared home. Still, regardless of the methods used for storing and cleaning the brushes, at least 60% tested positive for multiple people’s gut bacteria. Whether participants rinsed the brushes with cold water, hot water or mouthwash, it didn’t matter. There proved to be no universally safe method for storing the brushes, either, and in fact using one of those little covers made matters worse.
“Using a toothbrush cover doesn’t protect a toothbrush from bacterial growth, but actually creates an environment where bacteria are better suited to grow by keeping the bristles moist and not allowing the head of the toothbrush to dry out between uses,” said Aber.
The mouth is a particularly vulnerable site for the introduction of infectious diseases, made more so when it’s other people’s poop bacteria being introduced. In order to minimize cross-contamination, the ADA recommends against sharing tooth brushes, and says they should be rinsed cleanly and air dried, without coming into contact with other brushes. Though disease can be introduced through the mouth, there’s little evidence that bacterial contamination of brushes actually has any adverse affects on dental health, so you’re still better off brushing with a poo-covered brush than you are avoiding it altogether.
In the mean time, do your roommates a solid and but the lid down before you flush.