What police can learn about you from the skin chemicals on your cell phone

The UC San Diego method involves using a cotton swab to gather skin chemicals from the surface of a cellphone, then analyzing those chemicals with a mass spectrometer — a machine that helps categorize molecules based on the properties of their atoms. This was done for the 39 participants in the study. 

“We can detect thousands of molecules from a given object,” Dorrestein said. “Makes sense. They come from food, personal-care products, the environment you live in. But we can only annotate about 2% of the molecules we detect.

“We can tell you things like, ‘That’s [the pesticide] DEET,’ indicating the likelihood of a person who went into a place where there are mosquitoes. Then we see sunscreens. That indicates a person who likes to live outside. If there’s a lot of heavy makeup, that person is more likely to be a female than a male. These are the kinds of things we can learn from analyzing these kinds of chemistries.”

Other medications that Dorrestein’s team identified included hair-loss drugs, antidepressants, eyedrops and anti-inflammatory and anti-fungal creams. Food-oriented molecules included citrus, caffeine, herbs and spices, according to the study.

In the long run, scientists expect to understand more chemical signatures so they can annotate an ever-broader array of molecules.

On the phones tested, some of the molecular signatures were visible for a few days while others lasted for several months. The molecules were present even after the phones were cleaned, such as with wet wipes. That’s because they could be detected in cracks, edges or other parts of the phones that were hard to clean.

Conceivably, scientists might be able to use the spectrometer method for practical purposes other than law enforcement forensics work. The technology could, for instance, help doctors evaluate whether participants in a clinical trial are taking their prescribed medication or assist fashion designers to evaluate how a particular fabric interacts chemically with people’s skin.

Over the years, scientists have used cotton swabs to gather microbes off common objects, including pay phones and restroom sinks. But most of those studies involved processing the microbe’s DNA, which doesn’t give the sort of lifestyle information that Dorrestein is trying to develop with his technique.

Article Appeared @http://www.latimes.com/local/lanow/la-me-cellphones-20161115-story.html

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