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Flame Retardants Found in Rare Tasmanian Devils

Dave Hansford
for National Geographic News
January 28, 2008
 
Flame retardants that are suspected carcinogens have been found in some of Australia's Tasmanian devils, researchers announced last week.

The find triggered local media reports suggesting that the chemicals might be linked to the mysterious cancer that has been killing the rare marsupials for more than a decade.

A study conducted by the Australian government's National Measurement Institute took samples of fat from 16 living and dead devils, some of which suffered from the fatal devil facial-tumor disease (DFTD).

DFTD forms disfiguring tumors on the animals' faces and necks that cause them to die from starvation within about six months of showing symptoms.

The scientists found "high" levels of hexabromobiphenyl ether and "reasonably high" levels of decabromobiphenyl ether—chemicals used to treat electronics, textiles, and furniture.

Very high concentrations of such chemicals have been shown to cause cancer in lab mice, although no definitive evidence exists that the substances cause cancer in humans.

Warwick Brennan, a spokesperson for the Save the Tasmanian Devil project, said that expert analysis is needed before any conclusions could be drawn.

"The preliminary examination from our guys was that there weren't significant differences [of the levels of some compounds] between the diseased and non-diseased animals," Brennan said.

"But we're not toxicologists; we need experts to look at the data and get some meaning."

Cause and Cure?

Tasmanian devils are meat-eating marsupials that live primarily on Australia's island of Tasmania, just south of Melbourne (see map).

The animals' mysterious illness is one of only two known cancers able to spread like a contagious disease.

Since the illness was first detected in 1996, wild devil sightings have fallen by more than 50 percent.

The small carnivore is now considered "vulnerable" under Australia's Environment Protection and Biodiversity Conservation Act.

Experts have been racing to find the cause of—and hopefully a cure for—the illness before the devil goes extinct in the wild.

In February 2006 researchers announced that the disease most likely spreads when the animals bite each other during mating battles.

But no one is sure what triggered the cancer in the first place.

Hamish McCallum, professor of wildlife research at the University of Tasmania, said it's unlikely the chemicals caused the devils' disease.

"It's a really, really strange tumor. All the tumor cells in all the devils are essentially a clone—they are all derived from one individual," McCallum said.

"The event that caused that original mutation to malignancy will never be known," he continued.

"It happened a minimum of ten years ago, and in terms of managing the disease, it's essentially irrelevant."

However, "it's not beyond the bounds of possibility that [biphenyls] may suppress the devils' immune systems in such a way that it makes them more likely to develop the cancer," he said.

More Tests

McCallum thinks the devils in the new study could have easily ingested biphenyls directly.

"You've got to remember that devils are scavengers," he said.

"Throughout Tasmania … people maintain outdoor dumps. If somebody chucked a wallaby carcass on top of say, a foam mattress, then … the devils might actually consume quite large quantities of that foam."

In response to the new study, wildlife managers have called for funding for further, more comprehensive tests on the devils.

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