Are human beards dirtier than dogs?

Human beards contain more bacteria, and potentially more harmful bacteria, than dog fur, a study has shown...
26 April 2019


A bearded man's face


Human beards contain more bacteria, and potentially more harmful bacteria, than dog fur, a study has shown...

But don’t go shaving your beard off just yet, because there’s probably no real cause for concern! The work, published in the journal European Radiology, was trying to establish the risk, if any, of humans sharing scanners - such as MRI and CT machines - with man's best friend. The rationale is that there are 80 million pet dogs across Europe, the study points out, but a "pawcity" of dedicated vet scanners with which to image these animals when they need a scan.

The solution is to use hospital machines, but could putting pooches through the MRI suite "lead" to infection and cleanliness consequences?

To find out, Paracelsus Medical University in Austria's Andreas Gutzeit and his colleagues compared the bacteria recovered by swabbing MRI machines used exclusively by humans and similar machines that had been shared by both humans and dogs. They also pressed agar plates directly into the beards of 18 humans aged between 18 and 80, and the neck hair of 30 dogs from 16 different breeds.

As a beard-having human being, this got me a little anxious for the results!

Surprisingly, the authors found that the samples collected from the MRI machines shared by dogs and humans actually grew FEWER bacteria than the samples from the machines used only by humans. According to the researchers, the shared machines contained a “substantially lower bacterial load.”

This probably shouldn’t be surprising, given that the shared MRI machines were carefully cleaned after every patient, whereas the human-only machines were cleaned much less frequently. If nothing else, the study suggests that hospitals should probably be cleaning their MRI machines more often.

The study also showed that, on average, the men’s beards contained a higher bacterial burden than the dogs’ fur, with all 18 of the samples from beards yielding what the authors considered “high” densities of bacteria, whereas only 23 of the 30 dog samples did.

Disturbingly, the study also found that a higher proportion of the beards harboured “human-pathogenic bacteria” - classes of micro-organisms known to be potentially harmful for humans - although the result wasn't statistically significant.

Nevertheless, is the fact that some human beards contain a higher density of bacteria than dog fur cause for concern?

Thankfully, for those of us sporting luxuriant facial outgrowths, probably not. Discounting the non-statistically significant finding, we shouldn’t worry about high densities of bacteria, as most are harmless.

Indeed, bacteria are everywhere. There are very high densities on your skin, on doorknobs, handrails, and don’t even think about the smartphone or computer you’re currently reading this on. And, as the authors point out in their paper,  “there is no reason to believe that women may harbour less bacteriological load than bearded men.”

So, don’t worry. Beards may be kind of gross from a bacteriological point of view, but probably not any grosser than just about every other person or thing you came into contact with today!


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