Time-Trends and Congener Profiles of PBDEs and PCBs in California Peregrine Falcons (<i>Falco peregrinus</i>)

High levels (μg/g lw) of polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) were measured in peregrine falcon eggs from California (<i>n</i> = 90 eggs from 52 birds, 38 nest sites, collected 1986−2007, ΣPBDEs median = 4.53, range = 0.08−53.1). Over the past 22 years, PBDE levels more than tripled each decade in the eggs, whereas PCB levels had no significant changes. PBDE levels were highest in eggs from major California cities (“Big Cities”), whereas PCBs showed no difference across the regions. For PBDEs, Big City eggs had markedly different patterns from Coastal eggs: BDE-209 and the higher brominated PBDEs (hexa−nona) were dominant congeners in Big City eggs, while BDE-47 and -99 were dominant in Coastal eggs. In many of the birds that gave multiple eggs over time (“time series”), PBDE patterns changed over time: the high proportions of BDE-209 and higher brominated PBDEs (short half-lives) in young birds contrasted with increasingly higher proportions of BDE-153 (long half-life) and other lower brominated PBDEs as the birds aged. These data are consistent with metabolic debromination of BDE-209 (<i>t</i><sub>1/2</sub> = 1−2 weeks) to the lower brominated PBDEs, with accumulation over time of BDE-153 (<i>t</i><sub>1/2</sub> = 3−4 years). In contrast, PCB patterns showed no differences by locations, and did not change over time. Diet (prey birds) may explain the urban PBDE pattern, as the patterns in urban pigeons and peregrines were similar, with high proportions of BDE-209 and the higher-brominated PBDEs. Also, our prey data (feathers from peregrine nests) showed urban peregrines having a higher proportion (>2 fold) of granivorous/opportunistic birds (e.g., “introduced feral” pigeons, mourning doves, starlings) in their diet than coastal peregrines. In summary, these data indicate that BDE-209 exits consumer products as an environmental contaminant to be taken up by wildlife (particularly in urban locations), and undergoes metabolic debromination to the banned lower-brominated PBDEs. High levels of the higher-brominated PBDE congeners, especially in urban locations, permitted accurate measures of relative proportions of homologues in each of the hexa−nona congener classes. Using the major hexa−nona homologues in each of these classes, we propose a pathway for the stepwise, metabolic debromination of BDE-209.