SALT LAKE CITY, July 1 (UPI) -- Tons of illegal ivory are still sold by dealers who claim it was taken before a worldwide ban, but a new procedure can tests those claims, U.S. researchers say.
Poachers who kill elephants and dealers who sell tusks and ivory are up against a new weapon in the form of a test developed by University of Utah scientists.
By measuring radioactive carbon-14 from atmospheric nuclear bomb tests deposited in tusks and teeth, the method reveals the year an animal died, and thus whether the ivory was taken illegally, a university release reported Monday.
"This could be used in specific cases of ivory seizures to determine when the ivory was obtained and thus whether it is legal," geochemist Thure Cerling said.
International agreements banned most trade of raw ivory from Asian elephants after 1975 and African elephants after 1989.
The new test uses a "bomb curve," a graph showing changes in carbon-14 levels in the atmosphere from U.S. and Soviet atmospheric nuclear weapons tests in Nevada and Siberia from 1952 through 1962.
Although those levels peaked in the 1960s and have declined ever since, they are still are absorbed by and measurable in plant and animal tissues, the researchers said.
"With an accurate age of the ivory, we can verify if the trade is legal or not" when the age is combined with existing DNA analysis to determine if an elephant is from Africa or Asia, lead study author Kevin Uno said.
"Currently 30,000 elephants a year are slaughtered for their tusks, so there is a desperate need to enforce the international trade ban and reduce demand," he said.
The study was published in the journal Proceedings of the National Academy of Sciences.