Note to self: go buy a new toothbrush.

Researchers analyzed students at Quinnipiac University sharing bathrooms averaging about 9 users–essentially a dorm situation.

They found 60% of the toothbrushes they tested had fecal matter on them. Of those, 80% of the toothbrushes contained poop from someone other than the owner.

“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,” says Lauren Aber, a graduate student at Quinnipiac University, according to RTT News.

You live by yourself or with a spouse, so you’re safe, right? Wrong.

The Apex Tribune reports researchers claim even toothbrushes in that scenario are contaminated.

“The explanation is that these molecules make it onto toothbrushes after spreading through the air as a result of common, daily, much needed and inevitable activities such as flushing the toilet,” according to the news site.

Aber, one of the researchers, says capping a toothbrush could actually do more harm than good.

” … they actually facilitate the growth of bacteria by acting as an environment that keeps the bristles moist rather than allowing the head of the toothbrush to dry out between uses,” the Apex Tribune reports.

The American Dental Association recommends not sharing your toothbrush with another person, rinsing the toothbrush both before and after use and drying it out.