A Cooper’s Hawk found dead near Vancouver, Canada, has the unfortunate distinction of being the most polluted wild animal on record, thanks to a diet rich in landfill birds, scientists announced last week.

In a study published in the journal Science of the Total Environment, Canadian researchers analyzed the liver contaminants of 21 Cooper’s Hawks and six Peregrine Falcons from the Vancouver area. Both of these raptor species have are commonly found in cities, where they capitalize on the abundance of sparrows, robins, starlings, and pigeons. But urban pollution poses a major problem for them, says Kyle Elliott, a professor in McGill University’s Department of Natural Resource Sciences and co-author on the paper.

Several of the Cooper’s Hawks and Peregrine Falcons that the scientists tested contained high levels of polybrominated diphenyl ethers (PBDEs), a flame retardant commonly found in furniture, electronics, and automobiles. It was phased out in the United States and Canada in the mid-2000s, but still persists in commodities made in the 20th century.

Cooper's Hawk. Photo: courtesy of McGill University

One of the male Cooper’s Hawks that the researchers found was in particularly bad shape, with PBDE levels of 196 parts per million. It far surpassed the previous titleholder for most-polluted bird: a Peregrine Falcon from California with PBDE levels of 94 parts per million. By comparison, three Cooper’s Hawks tested on Vancouver Island, which is not an urban area, averaged PBDE levels of 3 parts per million.

“We expected levels to be fairly elevated but not as elevated as we found,” says Elliott, who worked alongside a team of government and academic scientists that included his father. “I think of Vancouver as a relatively green city, someplace where people are really into composting, recycling. And I think of Canada as a country where we have progressive legislation about this sort of thing.”

Raptors usually yield the highest levels of pollutants among birds, since they’re at the top of the food chain. Elliott believes that this hawk was eating starlings that had been nesting in and feeding from landfills. He doesn’t think that it died right away from the PBDEs; instead, the toxins probably made the bird susceptible to other causes of death. Flame retardants come with multiple risks. Studies have shown that PBDEs can alter thyroid hormone levels in pregnant women, with potentially harmful implications for their fetuses.

The good news, Elliott says, is that PBDEs appear to be disappearing from marine and freshwater food chains in North America. The bad news, though, is that they accumulate in landfills every time someone decides to clean house.

The PBDE ban doesn’t cover all the bases either. Chemical manufacturers are continually introducing new types of toxic flame retardants to the market. “You move a bromine atom from here to here, and then it’s legal again,” Elliott says. “I wish the onus were on the chemical manufacturers to prove that these substances are safe rather than on researchers to prove after the fact that there’s a problem.”

The problem is not only widespread: It’s also long lasting. Like DDT and polychlorinated biphenyls (PCBs), PBDEs persist in the environment. Both DDT and PCBs were banned in North America in the ‘70s. Yet in the Okanagan Valley, an agricultural area near Vancouver, levels of DDT are still so high that they’re preventing Peregrine Falcons from reproducing, Elliott says.

To find out what you can do to keep PBDEs out of your home and the environment, visit the Columbia Center for Children’s Environmental Health or the Environmental Working Group online.