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A new test based on environmental changes unleashed by atomic bomb tests could help save some of the 30,000 elephants slaughtered every year for their tusks.

Developed by University of Utah scientists, the test uses carbon dating to determine whether a particular piece of ivory is a legal antique or the product of modern poaching.

With new accelerator mass spectrometry, the test can glean results from much smaller ivory samples and is affordable for law enforcement at $500, according to a U. news release.

"We hope it will spur governments like our own to invest money into really trying to work on the poaching problem from all ends: buyer, seller, shipper," said geochemist Thure Cerling, the senior author of a study published online this week in the journal Proceedings of the National Academy of Sciences.

Cerling and his fellow researchers tested the method's accuracy on 29 tissue samples from animals and plants killed between 1905 and 2008.

The samples included 1962 grasses from Kenya, tusks from hippos and elephants, monkey hair, oryx horn and canine teeth.

The test measures the amount of carbon-14, an isotope created as neutrons from open air nuclear tests done between 1952 and 1962 bombarded nitrogen in the atmosphere. Carbon-14 entered the food chain and was absorbed by plants and animals. Though the levels peaked in the 1960s, the isotope is still measurable in elephants' tusks. It can tell scientists when the animal died, disproving smugglers' claims that ivory is from an animal killed before international bans on the trade were in place by 1989.

Publishing the study both publicizes the science and gives law enforcement a baseline for future prosecutions based on the technology, Cerline said.

"It has immediate applications [for] fighting the illegal sale and trade of ivory that has led to the highest rate of poaching seen in decades," said Kevin Uno, the study's first author, in a statement. Uno did the research for his University of Utah doctoral thesis.

There are some limitations to the method: As plants absorb carbon from the atmosphere, the amount of carbon-14 is expected to return to pre-bomb levels in about 15 years.

Cerling is a geochemist who studies animal diets using carbon isotopes — he recently helped determine when early human ancestors began eating grass-based foods — and has also worked with the group Save the Elephants. He and Uno were studying a different question about how isotopes are incorporated into animal tissues when they realized the concept could also fight poaching.

Elephants are intelligent, social creatures with family bonds not unlike humans, he said.

"Half the families we studied had at least one member killed in the last five years," he said. "What if half the families in Salt Lake had lost a member in five years?"

Illegal ivory sales also funds violence in Africa as militias in Darfur, Uganda, Sudan and Somalia use the proceeds for weapons.

The market for illegal ivory was on the wane by the 1990s, Cerling said, but it has ramped up again in recent years as new markets open up in Asia. Conservation groups say 70 percent of smuggled ivory goes to China. The second-largest illegal market is the U.S.

The African elephant population has now dwindled to 423,000 individuals.

Twitter: @lwhitehurst