Study measures carbon from nuclear weapons tests

For the first time, scientists are able to determine the year in which a piece of ivory was taken from an animal, offering hope for the fight against poaching.

The African ivory trade was largely banned by 1989, but in the US, ivory that was imported before the ban is legal. However, illegal ivory is still imported by dealers who claim it was taken before 1989, and until now there has been no test to prove otherwise.

Researchers from the University of Utah discovered that testing levels of carbon-14 absorbed by tusks allowed them to determine when the ivory was taken.

Carbon-14 was formed in the atmosphere when US and Soviet nuclear weapons were tested in Nevada and Siberia between 1952 and 1962.

By measuring the radioactive carbon-14 levels in tusks, teeth, horns and hair, scientists were able to determine the year in which the animal died from 1955 through to the present day.

"This could be used in specific cases of ivory seizures to determine when the ivory was obtained and thus whether it is legal," says geochemist Thure Cerling, senior author of a study about the new method.

The study, co-authored by conservationists, wildlife experts and geochemists, has been published online in the Proceedings of the National Academy of Sciences (PNAS).

Researchers hope that the method will be taken on by regulatory and law enforcement agencies in the fight against poaching.

Lead author Kevin Uno says the method "has immediate applications to fighting the illegal sale and trade of ivory that has led to the highest rate of poaching seen in decades."