How dental isotopes help bring home unidentified soldiers – @theU
One of the keys to bringing home unidentified military remains, including POWs/MIAs and more than 81,500 soldiers missing in conflicts dating back to World War II, is using science to determine where might be find their home. Scientists at the University of Utah are engaged in an effort, in support of the POW/MIA Defense Accounting Agencyto develop methods to trace the geographical origin of remains, including teeth.
Why the teeth? Because everyone’s body, including their teeth, contains a record of where they lived and traveled in the form of various stable isotopes of common elements. Through the Forensic Identification of Our Nation’s Deceased People with Element Mapping, or FIND-EM, project, Gabriel Bowen, professor of geology and geophysics, and his colleagues are developing a nationwide isotopic map to help to narrow down the geographical origin of the unidentified remains.
“This is a small piece of the puzzle, but something our research team is proud to contribute,” says Bowen, “If we can help investigators close even a few more families, the effort will be worth it.”
Learn more about the FIND-EM project here.
Your isotopic travel diary
University of Utah scientists are world-renowned experts in using isotope data for a wide range of forensic applications. Recently, they used isotopes to trace the origin of illegal ivory and learn about the socio-economic status and even diet of hair salon clientele based on hair cuts.
Why are isotopes such a valuable source of information? For a given element, oxygen for example, all the atoms have the same number of protons. But some atoms have different numbers of neutrons. These atoms, with very slight differences in weight, are all isotopes of the same element. Isotopes that are unstable and decay, releasing energy in the process, are radioactive isotopes. But stable isotopes are called, of course, stable isotopes.
Oxygen has three stable isotopes: oxygen-16, oxygen-17 and oxygen-18. About 99.7% of all oxygen atoms are oxygen-16. But about 0.2% is oxygen-18 and 0.04% is oxygen-17. These traces are what make isotope science interesting.
Take as an example a cloud that moves from the Pacific Ocean eastward across the United States. When the water vapor in this cloud first evaporates, the evaporation process favors the lighter isotopes, changing the ratios between the three oxygen isotopes. As the cloud moves eastward, first dropping rain on the Pacific coast and then moving inland, the precipitation process favors the heavier isotopes, which means that the isotopic ratios in the rainwater continue to change as the cloud continues to move.
Between this process and other processes that act on water as it moves through the water cycle, water in different parts of the country has different isotopic signatures. Thus, the water you drink determines the isotopic ratios that will then end up in your tissues and bones.
Why focus on teeth?
“First and foremost, teeth are often one of the best preserved parts of the human body after death, which is essential if the goal is to identify remains that may have been buried for almost a century,” says Bowen. And unlike hair, blood, or bone, which are continually replaced, teeth form at some point in a child’s life and trap isotopes taken from the locality where that child lives.
“That means we can go to a certain tooth in the dentition, say a second molar, and know that the chemical signature reflects an individual’s diet and location during a certain part of childhood, in that cases between about 3 and 7 years old,” says Bowen. “Because teeth form in a sequence, it is even possible to bring together information from different teeth to understand relocation during childhood.”
The challenge that remains, says Bowen, is that although we know that water isotopes vary across the United States, there is not yet enough data to construct a map that can relate the isotopic signature of a tooth at a location.
Bringing Unidentified Remains Home
Potential forensic applications of such a method abound. Researchers at the Defense POW/MIA Accounting Agency, charged with “providing their families and the nation with the most complete accounting possible of our missing personnel,” are also exploring the potential of isotope science. Bowen and his team, which now includes six researchers, staff and technicians, are working to support this effort by establishing a scientific basis for linking an isotopic signature in molars, particularly third molars or wisdom teeth, with an individual’s location history.
“Wisdom teeth reflect the teenage and preteen years,” Bowen says. “It is the period of life just before most service members joined the armed forces and is most immediately useful to investigators who may have limited information about the childhood history of missing service members, but know where they enlisted or registered for service.”
How does this help bring unidentified remains home? Suppose a World War II burial site in Europe is known to contain the remains of several unidentified American soldiers. And suppose the circumstances of the soldiers’ deaths are known to the extent that they can be attributed to a single platoon. If we know the geographic origin of the still untraceable soldiers in the platoon, then finding a molar that can be traced back to, say, the Pacific Northwest greatly narrows the search for other sources of evidence that can provide a positive result. . identification.
Build an isotopic map
For several years, Bowen and his colleagues worked on the first step in building an isotope map by sampling and analyzing isotopes in drinking water and groundwater across the country. For one of these sampling trips, Bowen flew a Cessna aircraft solo around the United States for 10 days, collecting 82 samples. The resulting isotopic map of groundwater was released in January 2022.
Now the project has focused on collecting isotopic values from donated teeth. The team works with dentists and oral surgeons, as well as people who have recently had wisdom tooth extractions, to create a database of a few thousand samples from the millions of people who undergo extractions. wisdom tooth every year.
“Once we’re able to compare the US dental database with these charts, we’ll learn just how strong the relationship between tooth chemistry and drinking water is,” Bowen says, “and we will also learn about other factors, such as diet or certain health conditions, that affect water/tooth relationships and should be considered when using dental data for human identification.
Potential donors complete a short survey. If the team determines that the teeth would be useful for the project, the donor receives a prepaid courier to send the teeth to the lab.
Laboratory analysis of teeth may seem like an unconventional way to honor members of the United States military service. But it’s in support of an effort that touches on one of the Army’s core values: leave no one behind.
“It’s both a measure of respect for our military and a source of strength within our armed forces,” Bowen said. “This commitment does not expire when a conflict ends.”
Learn more about the FIND-EM project and the tooth donation process here.