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Putting teeth into forensic science

By using the bomb curve data from above ground nuclear weapons testing during the Cold War (inset), Lab scientists can determine a victim’s birth date by examining dental enamel. (DTI/Photo Lawrence Livermore National Laboratory)
Lawrence Livermore National Laboratory

Lawrence Livermore National Laboratory

Mon. 21 June 2010

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LIVERMORE, CA, USA: In a large natural disaster or in an unsolved homicide case, knowing the birth date of an individual can guide forensic investigators to his or her correct identity. Using the Lawrence Livermore’s Center for Accelerator Mass Spectrometry, Dr Bruce Buchholz and colleagues at the Karolinska Institute in Sweden determined that radioactive carbon-14 (14C) remains in the dental enamel, the hardest substance in the body.

The radiocarbon analysis, which determines the amount of 14C in tooth enamel, showed that dating the teeth with the carbon-14 method would estimate the birth date within one year. Scientists can relate the extensive atmospheric record for 14C to when the tooth was formed and calculate the age of the tooth and its owner.

“Traditional structural re-creation methods used by anthropologists to determine age are often imprecise,” according to Dr Buchholz. “Radiocarbon dating gives a clear idea of the individual’s birth date.”

In the study, 44 teeth from 41 individuals were analysed using racemization (a chemical process in which one amino acid is converted to its counterpart) analysis of tooth crown dentine or radiocarbon analysis of enamel, and ten of these were split and subjected to both radiocarbon and racemization analysis. Combined analysis showed that the two methods correlated well.

Above ground testing of nuclear weapons during the Cold War caused a surge in global levels of 14C, or radiocarbon, which has been carefully recorded over time. Radiocarbon is naturally produced by cosmic ray interactions with air and is present at low levels in the atmosphere and food. Although nuclear weapons testing was conducted at only a few locations, excess levels of 14C in the atmosphere rapidly dispersed and equalised around the globe.

(Edited by Claudia Salwiczek, DTI)

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