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What do the molecules left behind on your posessions say about you?

Imagine a crime scene. The thief in question wanted to toy with the police, so they left behind their cell phone with wiped data and no fingerprints. Well…It turns out that idea wasn’t such a good one.

They can blame a new study which has discovered the presence of thousands of molecules on a person’s phone. The molecules, called trace molecules, are transferred from the owner’s skin to an object via touch. They include food particles, medications, beauty products, and so on. Crime Scene Investigators and forensic scientists can use this information to narrow down the list of potential suspects by creating a lifestyle profile.

“By analysing the molecules they have 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,” said Amina Bouslimani, a Post-Doc at University of California, San Diego, who performed research for the study.

Bouslimani conducted her research in the lab of Dr. Pieter Dorrestein. The Dorrestein lab specialises in mass spectroscopy, a technique which detects and identifies unknown molecules. Bouslimani’s study is unique because she applied mass spectroscopy to samples from everyday objects.

Mass spectroscopy sorts molecules in a sample by weight. The molecules then go through a database where they are identified by comparison against known compounds. To identify the trace molecules found on the cell phones of the 39 volunteers involved in the study, Bouslimani used the Global Natural Products Social Molecular Networking database (GNPS), which features data on thousands of products and drugs.

There are limitations, however. Bouslimani’s and Dorrestein’s goal is not to use trace molecules for a one to one identification of a person to an item, like a fingerprint does, but instead to understand the owner’s everyday life.

Other limitations involve the GNPS database. Many food products and materials have not been added yet, and therefore cannot currently be identified.

Bouslimani and Dorrestein are now extending their study to 80 people and taking swabs from other commonly used items such as keys and wallets. Their hypothesis is that these items will also contain trace molecules from the skin, because of how frequently we touch them.

Outside of CSI settings, Dorrestein and Bousilami see the method being used in the medical sector to monitor how well patients are keeping up with medical regimens, and in the environmental sector to see what chemicals people who live in certain environments are exposed to. Undoubtedly, the potential applications of the trace molecule technology are endless; perhaps something to remember the next time you pick up your phone.

Image: Honeyfangs (Via unsplash.com)

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