New tooth enamel dating technique could help identify disaster victims

September 14, 2005

LIVERMORE, Calif. - 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 dating technique to federal agencies as part of the Laboratory's scientific and technical assistance in response to Hurricane Katrina. LLNL also is assisting in setting up emergency high-bandwidth communications and wireless networks. The Laboratory's Micropower-Impulse Radar (MIR) technology also is being deployed to assist search and rescue crews in locating hurricane victims. This same technology was deployed in the days following the September 11 attacks in New York's World Trade Center rubble.

Carbon-14, or radiocarbon, is naturally produced by cosmic ray interactions with air and is present at low levels in the atmosphere and food. Atmospheric testing of nuclear weapons from 1955 to1963 produced a dramatic surge in the amount of radiocarbon in the atmosphere, Buchholz said.

"Even though the detonations were conducted at only a few locations, the elevated carbon-14 levels in the atmosphere rapidly equalized around the globe," he said. Since atmospheric testing was banned in 1963, the levels have dropped substantially as the carbon-14 reacted with oxygen to form carbon dioxide, which was taken up by plants during photosynthesis and mixed with the oceans.

"Because we eat plants and animals that live off plants, the carbon-14 concentration in our bodies closely parallels that in the atmosphere at any one time," he said.

Buchholz and his colleagues analyzed 33 teeth from 22 different people whose ages were known. The enamel separations were done at the Karolinska Institute, and sample preparation and accelerator mass spectrometry analysis was done at Lawrence Livermore.

The enamel dating technique doesn't work for people born before 1943, because all of their teeth would have been formed before testing began in 1955.

In their Nature paper, Buchholz and his colleagues note that the technique for carbon-14 analysis using accelerator mass spectrometry is becoming increasingly sensitive and inexpensive, suggesting that even though nuclear testing was conducted decades ago, enamel dating could be used for precise age determination "for a long time to come."
-end-
Founded in 1952, Lawrence Livermore National Laboratory has a mission to ensure national security and to apply science and technology to the important issues of our time. Lawrence Livermore National Laboratory is managed by the University of California for the U.S. Department of Energy's National Nuclear Security Administration.

DOE/Lawrence Livermore National Laboratory

Related Atmosphere Articles from Brightsurf:

ALMA shows volcanic impact on Io's atmosphere
New radio images from ALMA show for the first time the direct effect of volcanic activity on the atmosphere of Jupiter's moon Io.

New study detects ringing of the global atmosphere
A ringing bell vibrates simultaneously at a low-pitched fundamental tone and at many higher-pitched overtones, producing a pleasant musical sound. A recent study, just published in the Journal of the Atmospheric Sciences by scientists at Kyoto University and the University of Hawai'i at Mānoa, shows that the Earth's entire atmosphere vibrates in an analogous manner, in a striking confirmation of theories developed by physicists over the last two centuries.

Estuaries are warming at twice the rate of oceans and atmosphere
A 12-year study of 166 estuaries in south-east Australia shows that the waters of lakes, creeks, rivers and lagoons increased 2.16 degrees in temperature and increased acidity.

What makes Saturn's atmosphere so hot
New analysis of data from NASA's Cassini spacecraft found that electric currents, triggered by interactions between solar winds and charged particles from Saturn's moons, spark the auroras and heat the planet's upper atmosphere.

Galactic cosmic rays affect Titan's atmosphere
Planetary scientists using the Atacama Large Millimeter/submillimeter Array (ALMA) revealed the secrets of the atmosphere of Titan, the largest moon of Saturn.

Physics: An ultrafast glimpse of the photochemistry of the atmosphere
Researchers at Ludwig-Maximilians-Universitaet (LMU) in Munich have explored the initial consequences of the interaction of light with molecules on the surface of nanoscopic aerosols.

Using lasers to visualize molecular mysteries in our atmosphere
Molecular interactions between gases and liquids underpin much of our lives, but difficulties in measuring gas-liquid collisions have so far prevented the fundamental exploration of these processes.

The atmosphere of a new ultra hot Jupiter is analyzed
The combination of observations made with the CARMENES spectrograph on the 3.5m telescope at Calar Alto Observatory (Almería), and the HARPS-N spectrograph on the National Galileo Telescope (TNG) at the Roque de los Muchachos Observatory (Garafía, La Palma) has enabled a team from the Instituto de Astrofísica de Canarias (IAC) and from the University of La Laguna (ULL) to reveal new details about this extrasolar planet, which has a surface temperature of around 2000 K.

An exoplanet loses its atmosphere in the form of a tail
A new study, led by scientists from the Instituto de Astrofísica de Canarias (IAC), reveals that the giant exoplanet WASP-69b carries a comet-like tail made up of helium particles escaping from its gravitational field propelled by the ultraviolet radiation of its star.

Iron and titanium in the atmosphere of an exoplanet
Exoplanets can orbit close to their host star. When the host star is much hotter than our sun, then the exoplanet becomes as hot as a star.

Read More: Atmosphere News and Atmosphere Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.