The radioactive carbon-14 produced by above-ground nuclear testing in the 1950s and 1960s is providing forensic scientists with a more precise way to determine a person's age at the time of death. The method could help in the identification of victims of Hurricane Katrina and other large-scale disasters.
The new technique, developed by researchers at Lawrence Livermore National Laboratory (LLNL) and the Karolinska Institute in Sweden, determines the amount of carbon-14 in tooth enamel. Scientists can relate the extensive atmospheric record for carbon-14 to when the tooth was formed and calculate the age of the tooth, and its owner, to an accuracy of within about 1.6 years.
"Unlike most other tissue, dental enamel doesn't turn over," said Bruce Buchholz of LLNL's Center for Accelerator Mass Spectrometry, where the enamel samples were analyzed. "Whatever carbon gets laid down in enamel during tooth formation stays there, so tooth enamel is a very good chronometer of the time of formation.
"We were surprised at how well it worked," he said. "And if you look at multiple teeth formed at different times, you can get (the age range) even tighter." Previous techniques, such as evaluating skeletal remains and tooth wear, are accurate only to within five to 10 years in adults, Buchholz said.
The research was reported in this week's edition of the journal Nature.
Buchholz said Swedish forensic scientists already have used enamel dating to help narrow the search for victims of last December's tsunami in Southeast Asia. "After a few days in the water, it's very hard to identify someone," he said. "You can't use (enamel dating) to identify a person ?that requires a DNA analysis ?but you can narrow down the number of people you need to look at from a list of missing people."
Livermore officials are providing information on the enamel dat
Source:DOE/Lawrence Livermore National Laboratory