Researchers mine "user data" from smartphone smudge

Scientists have detected traces of everything from caffeine and spices to skin creams and anti-depressants on 40 phones they tested. Everything that people touch gets deposited with traces of chemicals, molecules, chemicals from their body. Even thorough washing of hands does little to prevent this, according to the researchers.

Researchers from the University of California San Diego, used a technique called mass spectrometry, to test 500 samples taken from 40 adults' mobile phones and hands.

They then compared these to molecules identified in a database and produced a "lifestyle profile" of each phone owner.

According to Dr Amina Bouslimani, an assistant project scientist on the study, the results were revealing. 

"By analysing the molecules they left behind on their phones, we could tell if a person is likely to be 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 to spend a lot of time outdoors - all kinds of things," she said, BBC reported.

Most of the transfer is thought to happen from people's skin, hands and sweat to their phone.

Mosquito repellents and sunscreens were found to linger longer on people's skin and phones, even when they had not been used for months.

From the tell-tale traces, the scientists were able to construct a lifestyle sketch of the phone's owner, including his or her diet, health status, locations visited and even preferred hygiene products.

According to the researchers they saw a  range of possible uses for such an analysis, from criminal profiling and forensics to health studies that monitored a person's exposure to toxins of adherence to a medicine regimen. 

"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, www.livescience.com reported. "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.