The Grime on Your Smartphone Can Reveal Your Secrets

cell phone, smart phone
(Image credit: Kostenko Maxim/

If the idea of someone digging up dirt about you is a concern, WikiLeaks may be only part of your worries. The dirt you leave behind on your smartphone also can reveal information about what you've been up to, according to a new study.

By taking just a quick swab of the chemical residue on a smartphone, scientists at the University of California, San Diego, could construct a lifestyle sketch of the phone's owner, including his or her diet, health status, locations visited and even preferred hygiene products.

The researchers said they see a range of possible uses for such an analysis, from criminal profiling and forensics to health studies that monitor a person's exposure to toxins or adherence to a medicine regimen. [Body Bugs: 5 Surprising Facts About Your Microbiome]

The analysis, described today in the journal Proceedings of the National Academy of Sciences, may not be able to identify individuals as well as tests using DNA or fingerprints can (although these also could be left on a phone). But the dirt on your smartphone can paint a rather complete picture of your day-to-day activities, the researchers said.

"All of these chemical traces on our bodies can transfer to objects," said Pieter Dorrestein, a professor of pharmacology at the UC San Diego School of Medicine, who led the study. "So we realized we could probably come up with a profile of a person's lifestyle based on chemistries we can detect on objects they frequently use," such as the person's phone.

For this study, Dorrestein's team analyzed chemical traces left behind on the phones of 39 volunteers. Researchers swabbed four sections on each phone as well as eight spots on each study participant's right hand. The scientists then conducted a technique called mass spectrometry on each of the samples to determine the types of molecules present. [9 Odd Ways Your Tech Devices May Injure You]

Once the samples were analyzed, the researchers compared what they found with a massive database of molecules from various commercial products and medicines. Results showed traces of medicines such as hair-loss treatments, antidepressants, anti-fungal skin creams and anti-inflammatory drugs; food ingredients such as herbs, spices and caffeine; and products such as sunscreen and DEET mosquito repellant even months after these two types of items had last been used by the phone owners.

"We could tell if a person is likely female, uses high-end cosmetics, dyes her hair, drinks coffee, prefers beer over wine, likes spicy food, is being treated for depression, wears sunscreen and bug spray — and therefore likely spends a lot of time outdoors — all kinds of things," said Amina Bouslimani, an assistant project scientist in Dorrestein's lab who was the first author on the paper.

Although the technique is in the early stages of development, it is fairly accurate and "can be used in [a criminal] investigation as … an assisting method of narrowing down the search to a smaller group of likely candidate people," Dorrestein told Live Science.

He said the technique can become more powerful as more molecules are added to the reference database, which his group has developed and expanded via crowdsourcing. Dorrestein added that the researchers are interested in the molecules of the most common foods, clothing materials, carpets, wall paints and anything else people come into contact with.

Dorrestein said that there could be a potential to analyze a person's gut microbes, which could reveal people's health status from traces of fecal matter that might be on the phone, although he didn't detect any in his study of 39 people. He said he is working with other scientists on the American Gut project to better understand the molecules and microbes in the human gut, to serve as another reference database.

The study was funded in part by the National Institute of Justice, which is the research, development and evaluation agency of the U.S. Department of Justice.

Follow Christopher Wanjek @wanjek for daily tweets on health and science with a humorous edge. Wanjek is the author of "Food at Work" and "Bad Medicine." His column, Bad Medicine, appears regularly on Live Science.

Christopher Wanjek
Live Science Contributor

Christopher Wanjek is a Live Science contributor and a health and science writer. He is the author of three science books: Spacefarers (2020), Food at Work (2005) and Bad Medicine (2003). His "Food at Work" book and project, concerning workers' health, safety and productivity, was commissioned by the U.N.'s International Labor Organization. For Live Science, Christopher covers public health, nutrition and biology, and he has written extensively for The Washington Post and Sky & Telescope among others, as well as for the NASA Goddard Space Flight Center, where he was a senior writer. Christopher holds a Master of Health degree from Harvard School of Public Health and a degree in journalism from Temple University.