Hair Tells Tale of Where You've Been

By Randy Dotinga
HealthDay Reporter
Monday, February 25, 2008; 6:00 PM

Copyright © 2008 ScoutNews, LLC. All rights reserved.

MONDAY, Feb. 25 (HealthDay News) -- The water you drink stays in your hair, and it may reveal details about where you've been, new research suggests.

By analyzing the makeup of water molecules from human hair, University of Utah scientists were able to roughly determine the regions where people recently lived. While the approach isn't always accurate, the researchers say it's correct about 85 percent of the time.

Although the discovery has some implications for medical research, its more immediate use might be in tracking the history of unidentified bodies and perhaps testing the alibis of criminal suspects. "The big picture is for us to provide a tool for law environment," said study author James Ehleringer, a University of Utah biology professor. "This is an attempt to really try to help."

According to Ehleringer, the researchers wondered about the potential secret history exposed by water after the anthrax attacks of 2001. "We began to ask whether microbes might record the water environment in which they were living," he said.

Water, after all, makes up a major chunk of the human body. It comes from not only the liquids that people drink but also the food they eat.

To figure out if they could detect a kind of fingerprint from water, the researchers extracted water molecules from protein in human hair. Then they broke the molecules apart and studied the concentration of heavy and light isotopes.

The study findings appear in this week's online issue of the Proceedings of the National Academy of Sciences.

The scientists found what they call an "isotopic fingerprint," a combination of the ratios of heavy and light isotopes in the hydrogen and oxygen of the water.

The fingerprints can give scientists a rough idea of where the water came from, depending on how heavy it is. This is not related to the more familiar concept of "soft" or "hard" water.

Due to variations in geography, water is heavier in some parts of the world than others, Ehleringer said. According to him, it's now possible to differentiate water that comes from different places.