There may be no marker of modern civilization quite like the shoe: not only does it make clopping around our cemented world significantly more tolerable (and less dangerous), but it also serves as an indicator of our sensibilities, our profession, our sense of style. You can tell a lot by the shoes people wear from the type of work they do to their income levels, even their political standings. And there’s something else shoes can tell us: whether or not we’re at risk of serious health issues.
A recent study out of the University of Houston found that 39 percent of shoe soles sampled were contaminated with the bacteria C. diff (Clostridium difficile), a public health threat that is now resistant to a number of antibiotics. C. diff infections can cause severe diarrhea that may progress to colon inflammation and more serious health issues, especially if it does not respond to antibiotic treatment.
“Shoes are contaminated from diverse sources, and we are regularly contaminating our doorsteps by shoes,” says study author M. Jahangir Alam, Ph.D.
Beyond the C. diff risk, there are all kinds of bacteria that could be sneaking into your home via your shoe: most public restroom floors contain about 2 million bacteria per square inch (the average toilet seat: only about 50 per square inch). Not exactly guests you want traipsing around your living room, especially if you have young children who spend a lot of time at floor level.
While it’s not quite as common in the West, most cultures around the world request that you leave your shoes at the door—not only does it keep those harmful germs out, but it’s also a sign of respect for the home, which should be considered a sanctuary away from the outside world.