What objects do you touch the most each day? If you're anything like most Americans, a smartphone is probably near the top of your list. In fact, there's a high likelihood you're holding it in your hand as you read this. The smartphone is a great tool, and can make our lives much easier, but this constant connection with a single device can be very revealing about us.

Obviously, the data stored on and transmitted by our phones can pose a security risk, and fingerprints on the screen could be searched in a law enforcement database. But that's not all — under forensic scrutiny, the smudges, dust, and grime on a phone can be used create a detailed profile of its owner's lifestyle.

Researchers at the University of California San Diego School of Medicine and Skaggs School of Pharmacy and Pharmaceutical Sciences recently conducted a study on this topic. Thirty-nine healthy adult volunteers handed over their cell phones to the researchers, who swabbed each phone in four locations.

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These swab samples were then analyzed using a mass spectrometer device to detect specific molecules. The molecules were compared against a massive database of known substances, in order to identify substances found on the phones. Here's where it gets really interesting: the substances were used to learn about the phone owner's lifestyle. Here's a list of a few of the substances found on swabs:

• Anti-inflammatory skin cream
• Hair-loss treatment
• Anti-depressant medication
• Eye drops
• Sunscreen
• DEET insect repellent
• Citrus
• Caffeine
• Herbs and spices

Amina Bouslimani, PhD, was one of the scientists involved in the research. She writes:

“By analyzing the molecules they’ve left behind on their phones, 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. This is the kind of information that could help an investigator narrow down the search for an object’s owner.”

Even a broken cell phone left behind by a criminal could be used to provide forensic data.

Senior author of the study, Pieter Dorrestein, PhD, hopes to broaden the molecular ID database to include more common items. These might include “the most common foods people eat, clothing materials, carpets, wall paints and anything else people come into contact with.” This line of forensic research is in its early stages, but could eventually be used to profile and track missing individuals or wanted criminals.

To learn more about this study, check out the full article from the UC San Diego Health Newsroom.

Written by Patrick McCarthy