Friday, July 3, 2009

Nuclear Bomb Tests Behind Ivory Dating by Julian Rush

Selling ivory is not illegal, providing it is from an elephant that died before 1947. But until now, proving the age of an item was notoriously difficult, relying on expert opinion.

Around the world, forgers have become adept at faking modern carvings to make them look old. Conservationists argued that sales on auction sites like eBay created a market that encouraged the forgers - and the poachers who kill elephants to meet the demand.

But now a sophisticated forensic scientific technique has been used for the first time in a court case of a woman accused of illegally offering carved ivory items for sale on eBay.

Following a tip-off from the National Wildlife Crime Unit, Hampshire Police raided the home of a woman from Aldershot in April 2007 and found 34 items. She was found not guilty at Winchester Crown Court last week.

The technique - radio carbon dating - is set to become an important weapon in the international fight against the illegal trade in animal parts and products that some suggest is worth billions of pounds a year.

For this case, Hampshire police called in the TRACE Wildlife Forensics Network who put them in touch with scientists in Scotland who specialise in radio carbon dating. It is usually used to date bones for archaeologists or rocks for geologists and uses the radioactive decay of carbon-14. 

Carbon-14 is a radioactive isotope of normal carbon and it occurs naturally in small quantities. It's taken up into the tissue and bones of every living plant and animal on Earth during life. At death, the carbon-14 starts to decay at a known rate, so by measuring the ratio of carbon-14 to normal carbon (which doesn't decay), scientists can determine the age of the sample.

That's fine for dating Neanderthal bones or an Egyptian mummy

Every Mushroom Cloud Has A Silver Lining

But in the 1950s and 60s, the fall-out from atmospheric nuclear bomb tests suddenly added extra carbon-14 to the atmosphere. All of us now have elevated levels of carbon-14 in our bodies as a result. And so too does every elephant, rhinoceros or walrus that's been alive since 1950. 

"If we find that the level of carbon-14 is enriched, then we know that elephant was alive in the nuclear era and therefore the ivory is illegal." Professor Gordon Cook, of the Scottish Universities Environmental Research Centre, who dated the ivory in this case, told Channel 4 News.

The spike is so high and so clear they can identify any organism that was alive after 1950.

Which, by chance, coincides almost exactly with the date for the age of ivory that can be legally sold. 

Though the woman was not convicted, TRACE, an international collaboration of campaigners, enforcement agencies and forensic scientists set up in 2006, believes the technique can be used successfully in future against the illegal wildlife trade like that in tiger body parts, rhino horn and scrimshaw. 

"We're now able to fully enforce the wildlife trade legislation. It opens the door for police to go after people trading illegally in ivory." said Dr. Ross McEwing of TRACE.

Professor Gordon Cook says the "nuclear bomb test" has wider uses. "It has huge potential. We've also looked at human teeth and we think we can tie down the year of birth by measuring the carbon-14. That, for something like mass graves, could be very important."

In January 2009, after a global campaign by environmentalists, eBay finally banned all sale of ivory.

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