Water Leaves Trail In Hair

Be careful where you drink. A University of Utah team led by geochemist Thure E. Cerling and ecologist James R. Ehleringer reports that the isotope ratios of human hair correlate with the isotope ratios of local tap water and can be used to track where people have been (Proc. Natl. Acad. Sci. USA 2008, 105, 2788). The team collected samples of barbershop hair clippings and drinking water from 65 cities in 18 states. A regression analysis of the isotope values in the hair against the isotope values of local drinking water suggests that a significant fraction of the hydrogen and oxygen in hair derives from local drinking water. The researchers predicted the hydrogen and oxygen isotope values in hair across the country on the basis of known isotope values in drinking water. They suggest that such information could be useful in forensic, anthropological, and archaeological studies.