Robert Hotz reports in the Wall Street Journal:
Traces of molecules and microbes left when you handle your phone can add up to a composite portrait, including gender, diet, medications, clothing, beauty products, and places visited. “We got 90% of the people correctly identified based on the chemistry of the phone.”
Those smudges on your cellphone reveal intimate details about your lifestyle, a new study says, potentially offering a new tool for criminal profiling, airport screening, clinical trials and environmental exposure studies.
Traces of molecules and microbes left when you handle your phone can add up to a composite portrait, including gender, diet, medications, clothing, beauty products, and places visited, researchers at the University of California in San Diego said Monday.
Such chemical signatures likely build up whenever someone regularly touches a phone, keys, credit cards, or other personal possessions—and can linger for months, they said.
The new forensic technique, reported in the Proceedings of the National Academy of Sciences, isn’t yet admissible in court, nor is it precise enough to indisputably identify a single person, like a fingerprint or a DNA sample, the researchers said. But it has the potential to help investigators use objects found at crime scenes to narrow the range of potential suspects.
“It could fill a unique niche in the forensic world for those cases where fingerprints cannot identify anyone and DNA sequencing cannot identify a person,” lead researcher
Existing forensic techniques have come under fire recently. The President’s Council of Advisors on Science and Technology concluded in a final report in September that much of the most common analysis used in criminal trials doesn’t meet scientific standards.
The final document nearly mirrored a draft report reviewed by The Wall Street Journal that raised questions about the use of bite-mark, hair, footwear, firearm and tool-mark analysis as evidence in thousands of trials annually in state and federal courts.
The new technique outlined in the report released Monday arises from basic research into the biochemistry of skin.
Last year, Dr. Dorrestein and his colleagues compiled the first three-dimensional maps of microbial variations across the entire body. They swabbed the skin at 400 places on the body. Using mass spectrometry, they analyzed the molecules in each sample, to understand the interplay of biochemistry, microbiology and health.
To ensure those samples were unsullied, they had asked volunteers to avoid bathing, shampooing or using any personal-care products for three days. The scientists were surprised to discover that the skin samples were still rich with traces of sunscreen and beauty products.
“We were so interested in the chemistry of the microbes that we didn’t think about personal-care products until we started seeing the data,” Dr. Dorrestein said. “Once we did that, we realized the potential for forensic applications.”
The new study was funded by the National Institute of Justice, the research arm of the U.S. Department of Justice.
The researchers tested 39 people and their cellphones. They took samples from the front and back of each phone and from the palm and fingers of each person’s right hand. They used a mass spectrometer to detect the molecules in each sample and, consulting chemical databases, identified as many of them as they could.
Among the medications detected on the phones were anti-inflammatory and antifungal skin creams, hair loss treatments, antidepressants and eye drops. They identified traces of citrus, caffeine, black pepper, and chili spices. Traces of sunscreen ingredients and DEET mosquito repellent also turned up.
“We got 90% of the people correctly identified based on the chemistry of the phone,” Dr. Dorrestein said.
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