Bioaccumulation and biotransformation of 61 polychlorinated biphenyl and four polybrominated diphenyl ether congeners in juvenile American kestrels (Falco sparverius)

Abstract

This study examined the bioaccumulation and dietary retention of 61 polychlorinated biphenyl (PCB) and four polybrominated diphenyl ether (PBDE) congeners in juvenile American kestrels (Falco sparverius). American kestrels were exposed to contaminants via egg injection and daily gavage dosing over the posthatch-to-fledgling period. Retention factors for PCBs were dependent on chemical hydrophobicity and chlorine substitution patterns and ranged from less than 1 to 16.4% for PCBs having vicinal hydrogen substitutions at meta-, para- carbons on at least one of the phenyl rings and between 13.2 and 81.5% for congeners containing chlorine substitutions at 4,4'-, 3',4,5'-, 3,4',5-, or 3,3',5,5'-positions. These results indicate that juveniles are capable of biotransforming PCBs according to the same structure-activity rules as adults. A toxicokinetic model, initially parameterized using adult toxicokinetic parameters, was used to describe concentration trends in juveniles over time. The adult model overestimated PCB concentrations but provided an adequate fit when elimination rate constants were increased by a factor of 12.7. Retention factors for the PBDE congeners 2,2',4,4'-tetrabromodiphenyl ether (BDE 47), 2,2',4,4',6-pentabromodiphenyl ether (BDE 100), 2,2',4,4',5-pentabromodiphenyl ether (BDE 99), and 2,2',4,4',5,5'-hexabromodiphenyl ether (BDE 153) were from 7.8 to 45.3% of the total dose. The retention of BDE 47 was similar that observed for readily cleared PCBs, whereas the remaining PBDEs exhibited retention factors consistent with those of persistent PCBs. Half-lives for PBDEs in juveniles were estimated to range from 5.6 to 44.7 d. Assuming differences in PBDE toxicokinetics between juveniles and adults similar to those measured for PCBs, adult American kestrel PBDE half-lives are expected to range from 72 to 572 d.

Effect of reduced food intake on toxicokinetics of halogenated organic contaminants in herring gull (Larus argentatus) chicks

“…This is in contrast to previous findings on American kestrels showing different retention factors for individual PBDEs [37]. MeOPBDEs were not detected in the herring gull chicks, although the dietary intake was relatively high (total intake of SMeOPBDEs through the contaminated oil 882 ng/g body wt).…”

“…2), suggesting that these PCBs were readily biotransformed in the exposed herring gull chicks. This is in accordance with previous findings on PCB biotransformation in seabirds [35,36] and American kestrels [37]. Because group IV and V PCBs are precursors of MeSO 2 -PCB [9], MeSO 2 -PCBs detected in the exposed herring gull may result from biotransformation of group IV and V PCBs.…”

Biomagnification of Higher Brominated PBDE Congeners in an Urban Terrestrial Food Web in North China Based on Field Observation of Prey Deliveries

“…5,7 The biodilution of BDE-47, -99, and -100 may be due to the rapid elimination of these congeners in the kestrel. BDE-47 has the lowest retention factor in administrated American kestrel, 10 and rapid elimination of BDE-47 in rats has been demonstrated by € Orn and KlassonWether. 31 The BMF values calculated in this current field study were very comparable to the values predicted in the American kestrel lab exposure study, i.e., 0.26 vs 0.25 for BDE-47, 0.42 vs 0.61 for BDE-99, and 0.61 vs 0.70 for BDE-100.…”

“…Nonsteady-state BMFs of PBDEs in juvenile American kestrels were also calculated in an administrated study. 10 However, none of these studies have evaluated the biomagnification potential of octa-to deca-BDE congeners, primarily because these congeners were not detected or levels were below limit of detection in the prey species and food items. Therefore, the biomagnification potential of higher brominated BDEs remains undetermined.…”

Occurrence and biomagnification of organohalogen pollutants in two terrestrial predatory food chains

“…The lower BMF values of BDE-47, -99, and -100 in the sparrowÀkestrel chain may be due to the rapid elimination rate of these compounds in kestrel species. In a laboratory study, in which American kestrels were exposed to Penta-BDE mixture, these three congeners showed a more rapid elimination rate than BDE-153 (Drouillard et al, 2007).…”