When you think of bald eagles, what comes to mind? More than likely it’s a vision of the majestic birds, soaring aloft, diving swiftly to catch a fish–not animals contaminated with toxic chemicals. It seems the latter is just the case in Michigan, where the state’s bald eagle population has the most contaminated birds on the planet, with abnormally high levels of flame-retardant chemicals in their livers.
A recent study published in the Journal of Great Lakes Research found that Michigan’s eagle population is contaminated with high levels of polybrominated diphenyl ethers, or PBDEs. These chemicals were added to things like furniture, electronics and clothing for more than 40 years to slow the spread of flames if the items should catch fire. The toxic chemicals were eventually phased out starting in the early 2000s as the chemicals were found to build up quickly in people and the environment.
Those chemicals can leach from the products in which they were used and stay in the environment for a very long time. According to Nil Basu, an associate professor at McGill University of Montreal, who carried out the study while at the University of Michigan, the eagles were most likely exposed to the PBDEs by eating contaminated fish–but the chemicals can also enter their bodies from landfills, via inhaled dust or by being licked off the eagles’ own feathers.
Basu said the chemicals “are everywhere. They build up in the food chains so that the top predators–such as bald eagles–accumulate high levels.”
The researchers tested the livers of 33 dead bald eagles that were collected between 2009 and 2011 by the Michigan Department of Natural Resources. The bird were tested for the four common types of PBDEs and scientists found all four chemicals in all but two of the birds tested.
According to the authors, the PBDE concentrations found in the Michigan eagles were “among the highest found in liver tissues of any wildlife,” with the levels in one eagle’s liver measuring 1,538 parts per billion. This doesn’t bode well for the natural populations of our country’s national emblem.