|
Hair test can map movements in US: study
2008-02-25
A single hair is all it takes to map a person's movements across the United States with a new test aimed at helping police check alibis and identify murder victims. Using tap water samples and clippings from barbershops across the country, researchers at the University of Utah were able to find significant chemical differences that can be used as geographic markers. "You are what you eat and drink -- and that is recorded in your hair," said geochemist Thure Cerling, who co-authored the study published Monday in the Proceedings of the National Academy of Sciences. The study found that 85 percent of the variation in hydrogen and oxygen isotope levels in a person's hair was due to variations in local drinking water. So a single strand of hair can help trace a person's location during recent weeks or even years, depending on the length of the hair and thus how much time it took to grow. Cerling and his team used the water and hair samples to produce color-coded maps showing how ratios of hydrogen and oxygen isotopes in scalp hair vary in different areas of the United States. The maps can't pinpoint an exact location but can be used to identify general geographic areas and has already been used to help trace an unidentified murder victim in Utah. "It's a phenomenal method," said detective Todd Park, who is using the new type of hair analysis in an effort to identify a murdered woman whose partial remains were found in Salt Lake County, Utah in October 2000. The hair sample told Park that she had spent the last two years of her life moving around within the Idaho-Montana-Wyoming area and possibly into Oregon and Washington state. An analysis of her teeth could show where she grew up. "Every little bit helps," the detective said. "You put pieces of the puzzle together to get a whole picture. And this is definitely something that will give us a piece of the puzzle." The technique could also prove useful for doctors trying to track to worsening symptoms of a dietary disease, and anthropologists or archaeologists trying to trace migratory patterns of long-dead peoples or animals, the authors said. A similar type of analysis developed by study co-author ecologist Jim Ehleringer is used by the US Drug Enforcement Administration to help determine where cocaine or heroin samples were produced.
| 
