By Xinhua
Los Angeles : US researchers have developed a new technique to identify murder victims and criminals through human hair, according to a new study.
By using this technique, scientists can determine where a person has lived based on the varied chemicals in drinking water across the country – variations that show up in hair, the study said.
The findings were published by the Proceedings of the National Academy of Sciences this week.
A team of researchers at the University of Utah collected tap water samples from 600 US cities and constructed a map of regional differences.
The researchers checked the accuracy of their map by testing 200 hair samples collected from 65 small-town barber shops.
They were able to accurately place the hair samples in broad regions roughly corresponding to the movement of rain systems across the country.
“You are what you eat and drink, and that is recorded in your hair,” said Thure Cerling, a geologist and lead author of the study.
Though the US diet is relatively homogenous, water supplies vary. The differences are a result of weather patterns. The chemical composition of rainfall changes slightly as rain clouds move.
Most of the hydrogen and oxygen atoms in water are stable, but traces of both elements are also present as heavier isotopes.
By measuring the proportion of heavier hydrogen and oxygen isotopes along a strand of hair, scientists can construct a geographic timeline. Each inch of hair corresponds to about two months, Cerling said.