Assessing Adverse Outcomes Associated with Exposure of Birds to Flame Retardants

Science Center Objects

The Challenge: The use of flame retardants (FRs) as additives in a variety of consumer use products, including plastics, textiles, and electronics, is projected to continue and increase for the foreseeable future. Because of unanticipated environmental problems, some FRs have either been banned, restricted, or are being phased-out and replaced by other new and presumably safer FRs. Regrettably, many of these alternative FRs are found to bioaccumulate in wildlife tissues, including in bird eggs, suggesting exposure through maternal deposition. However, few data are available on the potential adverse effects in exposed animals.

The Science:In collaboration with Environment and Climate Change Canada, USGS biologists from Patuxent Wildlife Research Center (PWRC) are investigating the effects of embryonic exposure to alternative FRs in birds. These studies employ avian egg injection methods developed at PWRC to simulate maternal deposition of pollutants. Studies to date, have examined the effects of four brominated FR (BFR) - tetrabromobisphenol A bis[2,3-dibromopropyl ether] (TBBPA-BDBPE), 2-ethylhexyl- 2,3,4,5-tetrabromobenzoate (EHTBB), bis(2-ethylhexyl)-2,3,4,5- tetrabromophthalate (TBPH), and 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE). These additive FRs are used in plastic products, resins, textiles, paints, and household electronics as replacements for the phased-out decabromodiphenyl ether (decaBDE), pentaBDE or OctaBDE FRs. Using American kestrel (Falco sparverius), a semi-altricial raptorial model, we examined the potential toxicity of these FRs on survival, growth, molecular, biochemical, histological and endocrine endpoints. Transcriptome sequencing (RNAseq) and digital gene expression are being used to identify affected pathways in the birds.

The Future: These studies will help determine the potential hazards posed by BFRs to free-ranging birds, providing critical data needed for understanding commonalities and differences in their modes of action. Findings will address the relationship between effects at lower levels of biological organization (e.g. molecular) and adverse effects at the individual, population or higher levels that are relevant to risk assessment and natural resource management.