It sounds like something from CSI or Law and Order: using a person’s hair to figure out where they’ve been.
Researchers from the University of Utah have been analyzing water molecules from human hair samples — and using the information to determine where the person lived. The process isn’t always accurate, but it’s pretty close. Analyzing the makeup of water molecules determines the right region of origin around eighty-five percent of the time.
This project was inspired by the 2001 anthrax attacks. Researchers wondered if microbes (like anthrax) might record the water environment that they came from. After that idea, the researchers turned their attention to the human body — which is mostly made up of water. Water in the body comes from the foods we eat and the liquids we drink.
In extracting the water molecules from human hair, scientists found what they call an “isotopic fingerprint” — a particular ratio of light and heavy isotopes in the hydrogen and oxygen molecules. The makeup of water varies from region to region, so the test could pick out the differences between a New Jersey water sample, an Ohio water sample, and a California water sample. They can’t pinpoint an exact city — two towns in California might have too similar a composition — but they can give an idea of the region of origin.
The University of Utah researchers are hoping that this process turns into a valuable tool for law enforcement — especially in the case of unidentified bodies. The hair test can give a clue as to how the victim spent their last few years. A similar test on the water in teeth can give a longer look into the past. Law enforcement officials believe that the more they know about an unidentified person’s past, the better chance they have of finding out who they are.
The water test may also be able to test the alibis of criminal suspects. In the medical world, the hair test could give clues to a person’s diet and whether or not they are drinking enough water.