Researchers from Leeds Teaching Hospitals in the U.K. detected C. difficile - a germ that can cause diarrhea and even life-threatening inflammation of the colon - nearly 10 inches above the toilet seat after flushing lidless hospital toilets. C. difficile is frequently found in hospitals and long-term care facilities were antibiotics are common.
"The highest numbers of C. difficile were recovered from air sampled immediately following flushing, and then declined 8-fold after 60 [minutes] and a further 3-fold after 90 [minutes]," the researchers reported in the January issue of the Journal of Hospital Infection.
C. difficile was spotted on surrounding surfaces 90 minutes after flushing, with an average of 15 to 47 contaminated toilet water droplets landing in the nearby environment, according to the study.
"Lidless conventional toilets increase the risk of C. difficile environmental contamination, and we suggest that their use is discouraged, particularly in settings where [C. difficile infection] is common," the authors wrote.
Although the study focused on hospital toilets, experts say the findings extend to public restrooms and households.
"Almost everywhere we go, except in some public spaces, we have lids on our commodes. But not everyone puts them down when they flush," said Dr. William Schaffner, chair of preventive medicine at Vanderbilt University Medical Center. "Doing so will reduce this type of environmental contamination very substantially."
A 2004 episode of Myth Busters found lidless toilets do indeed spray water onto surrounding surfaces - including toothbrushes - but concluded the health risk was negligible. In fact "control" toothbrushes removed from the restroom during the flush were also speckled with fecal bacteria.
In recent years, C. difficile infections have increased in number and severity - a trend Schaffner said might wane if more people opt to drop the lid.
"We don't know this, but it is intriguing," Schaffner said. "Just remember: put the lid down before you flush and always wash your hands."