A Burning Problem: Toxic Flame Retardants Found in Peregrine Falcons
What do your computer and a peregrine falcon have in common? For most of us in rural New England, it unfortunately isn’t speed. Rather it is polybrominated diphenyl ethers (PBDE), a group of chemicals used as flame retardants. There are dozens of varieties of PBDE. Furniture foam contains penta-BDE, computer plastics use octa-BDE, and TV cases and upholstery often have deca-BDE. The chemical prefixes signify the average number of bromine atoms per molecule of diphenyl ether.Unfortunately, falcons have traces of them all.
Peregrine falcons nest on high ledges near open areas across North America. With long, pointed wings and powerful talons, they can reach speeds of more than 200 mph when rocketing downward after avian prey. They were taken off the U.S. endangered species list a decade ago after recovering from the effects of organochlorine pesticides like DDT. Peregrines in New England were wiped out in the 1960s due to egg shell thinning from DDT. Young birds were released in the 1980s to help restore them to their lofty eyries. Their successful reintroduction has been heralded as one of the greatest conservation success stories in North America, but they may now be facing a new chemical threat.
The prevalence of PBDE accumulating throughout the food web has raised concern among scientists. Traces have been found in human breast milk, fish, birds and other wildlife throughout Europe, Asia, North America and even the Arctic. Scientists aren’t sure how PBDE enters the food web. It may be from releases during manufacturing, aging and wear of products, or, for humans, direct exposure during use.
Swedish researchers first discovered the flame retardants in fish in 1981 and more recently found that peregrine falcons eggs contained high levels of deca-BDE. Fearing that falcons in North America could be faced with the same threat, scientists have begun to document levels in their eggs. Because peregrine falcons are at the top of the food web they often get the brunt of any chemicals that bioaccumulate, making them effective indicators of the health of the environment.
A female falcon repeatedly dive-bombs and then soars skyward while cackling incessantly at Steve Faccio, a biologist with the Vermont Center for Ecostudies, as he repels down a cliff face towards her nest. Each year Faccio bands each chick to help monitor their survival. “A volunteer climber and I hike up to the cliff top, anchor our gear and repel to the nest ledge,” said Faccio. In addition to placing a small numbered metal band on each chick’s leg to help individually identify it like an avian social security number, Faccio collects any unviable eggs that may be left in the nest. “Actual collecting of an egg is always the first thing I do upon arriving at an eyrie,” Faccio exclaimed. “I carefully slip the greenish-brown egg into a plastic jar padded with foam to carry it back safely.”
Over 100 falcon eggs from across New England like those collected by Faccio have been analyzed by a team of scientists from the Virginia Institute of Marine Science, The College of William and Mary, the U.S. Fish and Wildlife Service and the National Wildlife Federation. They found unusually high levels of PBDEs. Two eggs collected in New Hampshire exhibited “extremely high levels” of total PBDEs, concentrations that “rival the highest PBDE burdens reported in wildlife to date,” wrote the authors in the journal Environmental Science and Technology.
What was unexpected was the amount of deca-BDE in the falcon eggs. Although total PBDE remained steady over the 10-year study, deca-BDE, once thought to be too big a molecule to cross cell membranes, doubled every five years in the falcon eggs. Deca-BDE remains the major PBDE in production worldwide.
While PBDEs do not produce the eggshell thinning associated with DDT, it has been shown to cause neurobehavioral, liver and thyroid problems in laboratory animals. “We don’t yet know the threshold for negative effects from PBDEs in falcons, and since peregrines are doing relatively well in the region, I don’t think we are seeing those effects yet,” says Margaret Fowle co-director of the Vermont Peregrine Falcon Recovery Project, a partnership between Audubon Vermont, the Vermont Fish and Wildlife Department and others.
Vermont had a record 38 pairs in 2008, while New Hampshire had 18 nests producing nearly 50 percent more young than a decade ago. “It is our hope that our monitoring efforts will detect any negative declines in the population,” says Fowle, “which may or may not be due to PBDEs.”
Scientists had already accumulated enough data to convince industry in North America to voluntarily cease production of penta- and octa-BDE in 2004. But the release of these BDEs from products is expected to continue for decades. In June Vermont passed legislation that will ban the use of all PBDEs in certain consumer products sold in Vermont. Perhaps New Hampshire won’t be far behind.