Exposure to brominated flame retardants and their associated effects on the growth and development, and breeding success in two avian models; the zebra finch and the European starling

In this study, both lab and field based methodologies were used to investigate the effects of brominated flame retardants on breeding success, and growth and development in two avian models: the zebra finch (Taeniopygia guttata) and the European starling (Sternus vulgaris). Firstly, captive-breeding zebra finches were used to investigate the effects of two brominated flame retardants, 1,2-dibromo-4-(1,2-dibromoethyl) cyclohexane (TBECH) and polybrominated diphenyl ethers (PBDEs), on growth, development, and reproduction. Chicks were exposed in ovo to TBECH, but there was rapid depletion of TBECH during embryogenesis, and we detected no adverse effects on chick growth. Chicks exposed post-natally to PBDE, via oral dosing, had elevated tissue levels of PBDE; however, no negative effects of PBDE treatment were detected for chick growth or adult size. There were also no significant effects of PBDE on breeding success for females that were exposed to PBDE as chicks. Secondly, we investigated the effects of exposure to environmental contaminants, primarily PBDEs, in free-living starlings breeding in a landfill site in Delta, BC, comparing this population to ‘reference’ populations in rural Langley, BC. Delta starlings had significantly higher levels of PBDEs in their eggs and chicks, eggs and chicks were structurally smaller, females provisioned significantly less for their offspring, and provided poorer quality food items including human refuse. Despite having potentially higher food availability at the landfill site, Delta females lost mass during breeding and had higher plasma NEFA and glycerol levels. Delta chicks also had significantly lower thyroxine levels than reference chicks, potentially due to the combined exposure to PBDEs and PCBs. Analysis of PBDE levels in landfill soils, and the starling food chain, indicated that contaminants are bio-accumulated in soil invertebrates and biomagnified in starlings. PBDE levels in the soil invertebrates and refuse consumed by starlings indicate that they are both significant contributors to the PBDEs levels measured in birds breeding at this site. This study shows the benefits of integrating both lab and free-living animal models to investigate the detrimental effects of exposure to environmental contaminants for risk assessment studies.