Brominated flame retardants: emerging risks to human health and the environment

A range of brominated flame retardants (BFRs) have been incorporated into plastics, electronic equipment, foams and textiles. Among the most common of these, polybrominated diphenyl ethers (PBDEs), have come under a great deal of scientific and regulatory scrutiny due to their persistence in the environment, bioaccumulation potential and toxicity. With bans and manufacture withdrawals of PBDEs occurring in many nations over the past 15 years, replacement flame retardants often referred to as “novel” brominated flame retardants (NBFRs) have been employed in consumer goods and products. These compounds are structurally similar to PBDEs and share similar physicochemical properties to their predecessors. Consequently, NBFRs are being detected in environmental and biotic matrices, including humans, with increasing regularity. At present, however, the legislative mechanisms which regulate and restrict the use of PBDEs do not apply to the most common NBFRs. The objective of this thesis has been to investigate the occurrence and fate of PBDEs and NBFRs in Australian indoor and outdoor environments. Central to this work has been the focus of elucidating major pathways of human exposure to the emerging compounds in relation to their banned legacy counterparts. The early stages of this project entailed the development and optimization of extraction and quantitation protocols using selective pressurized liquid extraction (S-PLE) and gas chromatography coupled to tandem mass spectrometry (GC-MS/MS). Using these methods, analysis revealed that both PBDEs and NBFRs are widespread in the surface soils of the city of Melbourne, Australia. These were the first measurements of PBDEs or NBFRs in Australian soils and provided baseline data against which to assess the implications of new health investigation levels (HILs) legislated in 2013. The survey of urban soils revealed a number of key potential sources to soils, including polymer manufacturing and waste disposal processes such as incineration and landfill. Among the land-uses studied however, contamination at electronic and electrical waste (e-waste) recycling facilities was 2- 3 orders of magnitude greater than the levels at other examined point-sources. A follow-up study investigating the spatial distribution of PBDEs and NBFRs in soils around these facilities determined strong evidence that e-waste recycling in Melbourne did in fact have the potential to contaminate land over distances up to 900 m, with concentrations in soil decreasing exponentially with distance from the source. The final aim of this research was to investigate the concentrations of PBDEs and NBFRs in indoor dust from homes, offices and vehicles in Melbourne and estimate human exposure via dust inhalation and ingestion. This study provided the first wide-ranging survey of NBFRs in indoor dust in Australia and offered further evidence of PBDE contamination in indoor environments. While PBDE contamination remained greater than that of replacement flame retardants, NBFRs were ubiquitously identified in samples. Key findings within this work suggested that the presence of some PBDE mixtures has been succeeded by certain NBFRs in materials from homes and offices and in vehicles. Exposure estimates calculated from the concentrations measured in dust revealed the majority of exposure to occur in the home for both adults and toddlers while toddlers were predicted to experience a dust-derived body burden of PBDEs and NBFRs 1 to 2 orders of magnitude above that of adults. As banned PBDE mixtures continue to be replaced by NBFRs in consumer goods manufactured in, or imported to Melbourne, ongoing environmental monitoring and toxicological studies are required in order to better assess the risks to human health and the environment