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Researchers find high levels of toxic flame retardants in Michigan bald eagles

Feb 19, 2015

A research team has discovered high levels of flame retardants in bald eagles in Michigan.

Polybrominated diphenyl ethers, or PBDEs, are in all kinds of consumer products.  They're in our couches, our TVs, our cars, our office chairs, the padding beneath our carpets, and the dust in our homes. But the chemicals don’t stay put. They leach out and build up in people and in wildlife.

"One thing to realize is that these chemicals were manufactured in the U.S., so it is possible that as a result of that, the levels are just higher in the U.S. and the Great Lakes region." — Nil Basu, researcher

"What we found was that some of the eagles, particularly in Michigan, had some of the highest exposures to flame retardant chemicals in the world," says Nil Basu, a professor at McGill University in Montreal.

  He and his colleagues studied PBDEs in otters and bald eagles in the Great Lakes region.

He says that overall, the findings are not surprising because scientists know that PBDEs resist degradation and therefore don't naturally break down.

"They're in the environment, they're in our air, water, soil and our food. And they can build up in the food chain," says Basu.

Why are levels higher in Michigan eagles?

But researchers were surprised to find that Michigan eagles had among the highest levels in the world even when compared with birds of prey in Europe and China. 

"One thing to realize is that these chemicals were manufactured in the U.S., so it is possible that as a result of that, the levels are just higher in the U.S. and the Great Lakes region," says Basu.

Eagles sit at the top of the food chain, which is why they accumulate chemicals in their bodies.

The research team also looked at the levels of PBDEs in otters from Wisconsin. 

"In the otters we found similarly, relatively high exposures to the flame retardants, but compared to the eagles in Michigan, the levels were just not that high," he says.

Basu says it's not clear whether the PBDE levels they found in eagles are affecting the birds' health, but he says laboratory studies have clearly shown that exposures to these flame retardants can be associated with damage to the brain, the liver, the immune system and thyroid.

What about newer flame retardant chemicals?

The penta form of PBDE has been phased out of production and replaced by other kinds of flame retardants.  Basu says scientists are working quickly to assess the replacement chemicals. 

His research team has started to study organophosphate flame retardants and while he says they don't have all of the results yet, they have started to find evidence of this chemical in wildlife. 

"So just like we saw with PBDE-type flame retardants a decade or two ago, the replacement flame retardants are now being used and we're now detecting them in our air, water and soil, wildlife and in people. We need to next ask whether or not they're causing effects."