Record-high PBDEs in Chinese birds of prey
Hawks, owls, and buzzards in China are taking up very high levels of PBDEs, particularly the Deca formulation.
The first report of polybrominated diphenyl ether (PBDE) flame retardants in terrestrial animals in China, published today on ES&T’s Research ASAP website (10.1021/es062045r), reveals that the country’s birds of prey have some of the highest levels of the persistent, bioaccumulative, and toxic contaminants ever recorded in an animal. The paper’s findings are remarkable for documenting that the Deca PBDE formulation used predominantly in China—now the only PBDE formulation used in Europe and North America—can bioaccumulate to a much greater extent than previously believed possible, according to researchers.
Da Chen of the Virginia Institute of Marine Sciences (VIMS) and his colleagues report record-high levels of the primary constituent of the Deca formulation, brominated diphenyl ether (BDE)–209. The scientists tested eight species of birds listed as National Key Protected Wild Animals in China, including hawks, owls, and buzzards. The birds, which had died from other causes, were donated by the Beijing Raptor Rescue Center. Chen analyzed them at China’s State Key Laboratory of Organic Geochemistry in Guangzhou.
Common kestrels from Beijing harbored the highest levels of both overall PBDEs and BDE–209. The most contaminated bird was a kestrel with 40,900 nanograms of total PBDEs per gram of tissue (ng/g, lipid weight) in its liver, including 12,200 ng/g of BDE–209. This is by far the highest level of BDE–209 ever reported in wildlife and is close to the maximum concentration of total PBDEs recorded for a single animal, points out Rob Hale, Chen’s advisor at VIMS and the paper’s corresponding author.
The European Brominated Flame Retardant Industry Panel points out that the other species of birds discussed in the ES&T paper had PBDE concentrations “within the range that has been found in other studies.” Cynthia de Wit of Stockholm University, the corresponding author of a study looking at PBDEs in European falcons, agrees. However, the kestrels’ PBDE levels imply that the animals they eat—including small mammals, small birds, earthworms, and insects—are “much more contaminated,” de Wit adds.
Barnett Rattner of the U.S. Geological Survey’s Patuxent Wildlife Research Center has been evaluating how PBDEs may impact American kestrels, which are similar to the common kestrels evaluated in Chen’s work. Rattner and graduate student Moira McKernan have found that the lower-weight PBDE compounds, or congeners, associated with the Penta and Octa formulations that have been banned in Europe and discontinued in North America can affect hatching success at “levels higher than, but approaching, what we see in the environment.” The ES&T study documents significant quantities of these lower-weight congeners in the common kestrels as well as in two species of sparrowhawks and long-eared owls.
The $64,000 question is whether these Chinese birds are taking up the lower-weight PBDE congeners by breaking down the BDE-209 from the Deca formulation or by getting them from other uses of the Penta and Octa formulations, Rattner says. Neither Penta nor Octa is known to be used in great quantities in China.
The presence of high quantities of BDE–207 and BDE–208, which are not found in the Deca formulation, in some of the Chinese birds suggests the BDE–209 is being broken down into lighter-weight PBDEs, points out Linda Birnbaum (18KB PDF), director of the experimental toxicology division of the U.S. EPA’s National Health and Environmental Effects Research Laboratory.
However, “it is very difficult to determine if the [congeners such as BDE–207 and BDE–208] are the result of debromination and metabolism within the birds,” says Heather Stapleton at Duke University’s Nicholas School of the Environment. “It is feasible that you could be getting BDE–209 in those terrestrial environments from a landfill, and photodegradation could be breaking it down. Those breakdown products could be accumulating in insects and small rodents around the landfill.”
Either way, continuing use of the Deca formulation could result in an environmental catastrophe, contends Åke Bergman, head of Stockholm University’s environmental chemistry department. The finding portends that these PBDEs are probably in people as well as other terrestrial animals in China and that widespread use of Deca in Europe and North America could lead to similar buildup in food chains there, Bergman says.
