Highlights
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- The Delta landfill is clearly a source of PBDEs for starling chicks.
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- BDE-47 and BDE-99 are the major PBDEs in starling chick plasma.
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- In vitro and in vivo metabolism of BDE-47 and BDE-99 in starling is very slow.
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- Differences in BDE-47 and BDE-99 in vitro metabolism by human, rat and starling exist.
Abstract
In
this study, the levels of polybrominated diphenyl ethers (PBDEs),
HO-PBDEs, and bromophenols were monitored in starling chick plasma
samples collected in Delta (British Columbia, Canada) close to the
Vancouver municipal landfill and in Glen Valley, a rural area in British
Columbia. The in vitro formation of hydroxylated metabolites
of 2,2′,4,4′-tetrabromodiphenyl ether (BDE-47) and
2,2′,4,4′,5-pentabromodiphenyl ether (BDE-99) was also investigated
using starling chick liver microsomes. Total PBDE plasma levels were
approximately 60 times higher in starling chicks from Delta than from
Glen Valley, suggesting that the Delta site is a major source of PBDEs
for the local population of starlings and that PBDEs previously measured
in starling eggs are bioavailable to chicks. In both locations, BDE-47
and BDE-99 were the two major congeners present at similar
concentrations, suggesting contamination with the Penta-BDE mixture.
Among the several possible hydroxylated metabolites of PBDEs monitored
in starling plasma, only 2,4,5-tribromophenol was detected and its
levels did not exceed 18 ± 7 pg/mL. Also, several hydroxylated
metabolites of BDE-47 and BDE-99 were formed by starling chick liver
microsomes, but in low amounts. Therefore, our data consistently suggest
that oxidative metabolism of PBDEs in starling chicks proceeds at low
rate in vivo and in vitro. In conclusion, the landfill
located in Delta is a relevant source of bioavailable PBDEs for the
local starling population. Because of the limited ability of starling
chicks to metabolize PBDEs, these compounds are likely to bioaccumulate
in starlings over time. The possible toxicological implications of PBDEs
bioaccumulation in starlings are currently unknown and require further
research.
Abbreviations
- BDE-47, 2,2′,4,4′-Tetrabromodiphenyl ether;
- BDE-99, 2,2′,4,4′,5-Pentabromodiphenyl ether;
- CYP, Cytochrome P450;
- CMP, Environment Canada Chemical Management Plan;
- GC-ECNI/MS, Gas chromatography–electron capture negative ionization mass spectrometry;
- HO-PBDEs, Hydroxylated PBDEs;
- LOQ, Limit of quantification;
- NADPH, Nicotinamide adenine dinucleotide phosphate;
- PBDEs, Polybrominated diphenyl ethers;
- SPE, Solid-phase extraction
Keywords
- PBDEs;
- HO-PBDEs;
- Starling chicks;
- In vitro metabolism;
- Liver microsomes
Copyright © 2015 Published by Elsevier B.V.
