What your phone’s surface reveals about your lifestyle

Molecular traces left on cell phones can tell researchers everything from what you had for breakfast to your shampoo preferences.

Whenever we touch something, we leave behind a unique chemical signature that reflects countless aspects of our daily lives. In a new study published in PNAS, researchers show that these clues can be collected from the surfaces of cell phones to narrow down who may have owned or used them – a great tool for forensics. We speak with senior author Pieter Dorrestein to learn more.

ResearchGate: What kinds of molecular signatures do we leave on our cell phones?

Pieter Dorrestein: Any lifestyle chemistry: beauty and hygiene products, food, medications, building materials we interact with, clothing, as well as molecules from skin cells, including the microbes that live on us.

RG: How long does the signature remain on the item? Does cleaning the item erase these signatures?

Dorrestein: Some molecules are only visible for a few days; others can stay six months. We do not fully understand how these aspects of the signature can last that long. As far as cleaning, all we know at this time is that we can recover a larger number of molecules from some phones than others. But all 39 phones we tested had molecular signals. We have not tested to see how much cleaning one needs to do, but the molecules may be recovered from any little hole or crack that might be hard to clean.

RG: How did you match the molecules from the samples in the study to specific products and activities?

Dorrestein: We weigh the molecules and break them apart resulting in a barcode for each molecule detected. This is then compared in an analysis infrastructure called GNPS to generate a list of molecules and related molecules.

RG: Based on your results, which aspects of our day-to-day lives have the biggest influence over the composition of our chemical signature?

Dorrestein: This depends on the individual’s habits. If one uses a lot of make-up and personal care products, then this is the dominate signature we see. If one does not use such products food and other molecules become dominant.

RG: How would the forensic application of this technique differ from identification techniques like fingerprints or DNA analysis?

Dorrestein: In our case, we do not need a database to match to a person. In fact, the goal of this approach would not be to match to a person at all, but rather to narrow down a list of people to whom the object could belong to. You can think of our analysis as a lot of little clues. For example, if there is make up it is more likely it is a female. If there are plant molecules and not any meat molecules then this person may be a vegetarian. If one sees molecules that are in shampoos that have ingredients to promote hair growth, then this person is losing hair. Through all the little clues one can perhaps narrow down the type of person to look for. In many respects, it is profiling without a preconceived bias.

RG: Are there applications beyond forensics?

Dorrestein: Yes, it has potential, but still needs to be assessed. For example, stratification of patients in clinical trials to ensure that medications are used by people for whom they work best. Assessing quality of food or improving manufacturing of clothes and materials that interact with people’s skin are some other examples.

Featured image courtesy of Adam Fagen