More than 60% of toothbrushes collected from shared bathrooms contained fecal matter, the researchers found.
What is more, the researchers found there was an 80% chance that the fecal contamination identified on the toothbrushes came from other people using the bathroom - a worrying finding.
"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," explains study author Lauren Aber, a graduate student of Quinnipiac University in Hamden, CT.
Such contamination is likely because toothbrushes are openly stored, the researchers explain, which exposes them to material from the toilet or microorganisms from other occupants.
The researchers note that Enterobacteriaceae and Pseudomonadaceae are some of the species of bacteria that can potentially contaminate toothbrushes. Both bacteria can be found in normal gut flora, though some forms can be pathogenic.
Bathroom sharers should adopt better hygiene practices
To reach their findings, Aber and colleagues collected and tested toothbrushes from students' communal bathrooms at Quinnipiac University. Each bathroom had an average of 9.4 users.
Not only did they find that more than 60% of toothbrushes were contaminated with fecal matter - most likely from other bathroom users - they found there were no differences between certain toothbrush cleaning methods, such as rinsing with mouthwash or cold and hot water, against contamination.
But while toothbrushes may be susceptible to contamination through open-air exposure, the team warns against using toothbrush covers - they actually encourage bacteria to spread.
"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," explains Aber.
Based on their findings, Aber says:
"Better hygiene practices are recommended for students who share bathrooms both in the storage of their toothbrush but also in personal hygiene."
The team recommends that people who share bathrooms follow the toothbrush hygiene recommendations set by the American Dental Association. These include:
- Avoid sharing toothbrushes
- Do not cover toothbrushes or store them in closed containers
- Replace toothbrushes at least every 3-4 months
- Rinse toothbrushes thoroughly with tap water after use and allow them to air-dry.
It is not only fecal contamination on toothbrushes we should be concerned about. In 2011, Medical News Today reported on a UK study that found 1 in 6 cells phones are contaminated with fecal matter.