What your phone residue says about you


Airport security is already using the technology to check for traces of explosives, but the residue on your smartphone also tells a story about your interests, health and what you spend your money on.

A research project by a group of scientists in the US has tested whether it's possible to get an accurate depiction of a person based solely on the molecules they leave on their cellphone.

They tested the phone screen and back case from 39 volunteers, and University of Auckland microbiologist Siouxsie Wiles says the chemical signatures on each side give quite different pictures of the person.

"The front of your phone is more like your face, which has microbes and things on it, while the back of your phone is more like your hand, which I guess is where you hold it," she told Paul Henry.

"They found things like sunscreen, insect repellents, medications, caffeine - all sorts of things."

She said from the residue taken from swabs of the phone, the scientists were then able to build up the profiles of some of those who volunteered.

"They only identified about 2 percent of the chemicals they actually found on the phone, but they then used some nifty software to build up a picture of the person that had it."

The software works by comparing the chemicals on the phone to those found in the Global Natural Product Social Molecular Networking database, which keeps a directory of the chemicals in thousands of medications and products.

The profiles were able to tell things like whether they were using hair growth hormones, whether they liked spicy food, which medication they used, whether they spent a lot of time outside or if they were a coffee drinker.

The study's authors say the kind of information they can gather from the test could prove hugely valuable to police, and could narrow down a search for an object's owner.

"You can imagine a scenario where a crime scene investigator comes across a personal object like a phone, pen or key without fingerprints or DNA, or with prints or DNA not found in the database," senior author Dr Pieter Dorrenstein said.

"So we thought - what if we take advantage of left-behind skin chemistry to tell us what kind of lifestyle this person has?

"All of the chemical traces on our bodies can transfer to objects - so we realised we could probably come up with a profile of a person's lifestyle based on chemistries we can detect on objects they frequently use."