Molecules Left on Your Phone Screen Can Reveal Whether You Like Spicy Food

As if the irritating iOS updates, fake Facebook news, and sleep-disrupting blue light weren't enough to make you reassess your relationship with your smartphone, here's another: the traces all that right-swiping and subtweeting leaves on your screen could reveal some of your most intimate secrets.

A new study from the University of California San Diego (UCSD) has found that the molecules left behind on everyday objects such as phones, pens, and keys can be used to glean information about the owner's health and lifestyle—including their food choices.

The study saw UCSD researchers test 500 samples taken from 40 people's phones and hands, and used a technique known as mass spectrometry to identify the individual molecules present. They compared these molecules with the Global Natural Product Social Molecular Networking database, which records the chemical makeup of drugs and other products.

This allowed researchers to produce a "lifestyle profile" for the owner of each phone. They were able to tell the sex of each person, as well as whether they suffered from allergies or depression, based on the presence of medication.

The molecules revealed lifestyle information, too. Researchers also used the phone screen samples to find out whether a person liked spicy food or preferred beer to wine. Food molecules like caffeine, citrus, and herbs were also shown to be present even months after they had been consumed by the owners.

Dr Amina Bouslimani, who assisted on the study, explained in a statement: "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."

The researchers added that traces of molecules are left on everything we touch, even when hands have been washed. They hope that the lifestyle profiling demonstrated in the study could be used to identify criminal suspects.

Study senior author Dr Pieter Dorrenstein said: "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. So we thought—what if we take advantage of left-behind skin chemistry to tell us what kind of lifestyle this person has?"

It seems all those secret evenings spent scrolling Pinterest with a solo glass of Chardonnay aren't so secret after all.