Phone Biome

Here is a strange fact: there are more people who own a mobile phone than have access to a working toilet. In the U.S., about two-thirds of the people you meet own a smartphone and it is even higher among younger Americans at 85 percent. People have gotten increasingly reliant on them and most would not want to live without one. A recent study has revealed that the microbiome on a smartphone reflects that of their owner’s skin.

Scientists hypothesized that the microbes found on smartphones could provide information about our personal microbiomes. The microbiome is the collection of microbes such as bacteria, viruses and fungi that co-exist in and on our bodies. It is estimated that on or in the human body, there are ten times as many microbial cells than human cells, and the majority have not been identified.

The microbiome varies depending on the location in or on the body. Microbes in a particular location are those that can best use the resources available to survive and reproduce. The microbiome is important in maintaining health and an imbalance can lead to health conditions like acne, allergies, diabetes, cavities and obesity.

Your personal microbiome is unique and varied, even on the skin. Because people take smartphones everywhere, both the phones and their owners end up being exposed to the same environmental microbes. This could make the microbiome of someone’s cell phone overlap with that of their skin. The microbiome found on the phone could even be used to identify the owner.

In a recent study, scientists sampled people’s forefingers, thumbs and smartphones. They then used molecular biology techniques to identify the bacteria in the samples. They discovered over 7,400 types of bacteria. They found that 82 percent of the most common bacteria on fingers were also found on phones. The most abundant bacteria on fingers and phones are Streptococcus and staphylococci species. The forefinger and thumb shared 32 percent of bacterial species between them, and both fingers shared 22 percent of bacteria with the phones.

Men and women had differences in their bacterial communities, and bacteria on women’s phones more closely resembled that of their skin than men. The population of bacteria on phones more closely resembled that of their owners than other people. On average, people touch their phones 150 times a day, so sharing only 22 percent of bacteria with the skin may seem low. However, that number reflects the bacteria that can survive on the phone and does not account for bacteria from other bodily sources such as saliva.

So, can the bacteria on cell phones be a danger? There is no evidence that bacterial pathogens on smartphones influence the rate of hospital-acquired infections. There is also no evidence that smartphones are any more of a risk than other possessions, though people interact with them and share them a lot.

Our microbiome is always along for the ride and we are constantly depositing and picking up microbes as we interact with our environment. Despite this, our microbiome is remarkably stable and our little passengers keep us healthy.

Medical Discovery News is hosted by professors Norbert Herzog at Quinnipiac University, and David Niesel of the University of Texas Medical Branch. Learn more at

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