Your hair holds your history

By analysing 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 the 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.

How the study was done
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 the 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.

The technique can't pinpoint an exact city or town, but can say whether water came from a kind of place, such as a coastal region, he said. "For instance, if you were to give me bottled water from Sacramento, California, and Denver, Colorado, I could easily tell them apart," using the technology, he said. "But I might not be able to tell apart something from Sacramento, California, versus Fresno, California. That might be too close a region."

And what about people who only drink bottled water that may come from far away? Unless they boil their potatoes and make their coffee and bottle their beer in the water, local water will still show up in their bodies, Ehleringer said.

Technology to be used in medicine too
According to the researchers, the technology could be used in medicine. Hair might indicate that someone such as a diabetic drinks a lot of water, or could offer clues to someone's diet.

Law enforcement is already using the technology. In Utah, homicide detectives tested the hair of an unidentified murder victim and discovered that she probably moved around the Northwest in the two years before she died.

Next, the scientists are planning to figure out where she grew up by testing the water in her teeth. "I think you'll see this technology has an impact on identifying unidentified victims from around the country," said Todd Park, a Salt Lake County sheriff's homicide detective. "The more specific information I can get about my victim, the better the odds will be for me to find out who she is." – (HealthDay News) - February 2008

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