Brominated flame retardants (BFRs) in Western Australian biosolids and implications for land application

This study evaluates the prevalence of eight priority polybrominated diphenyl ethers (PBDEs; -28, -47, -99, -100, -153, -154, -183 and -209) and six novel brominated flame retardants (NBFRs; pentabromotoluene (PBT), pentabromoethylbenzene (PBEB), hexabromobenzene (HBB), 2-ethylhexyl-2,3,4,5-tetrabromobenzoate (EH-TBB), 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE) and decabromodiphenyl ethane (DBDPE)) in biosolids samples from 15 wastewater treatment plants (WWTPs) in Western Australia. Analytes were extracted using selective pressurized liquid extraction (S-PLE) and quantified by gas chromatography coupled to tandem mass spectrometry (GC-MS/MS) operated in electron impact (EI) ionization mode. ∑₈PBDE levels in biosolids ranged from 11 to 18,000 μg/kg dw with a median concentration of 1800 μg/kg dw. BDE-209 was the most prevalent congener constituting a median of 98% of ∑₈PBDE concentrations in samples with BDE-99, -47 and -100 each typically contributing less than 3% to total levels. NBFRs were detected in 71% of samples with ∑₆NBFR levels ranging between ND-1100 μg/kg dw (median; 600 μg/kg dw). Levels of DBDPE greatly exceeded those of all other NBFRs, while the next most prevalent compounds were EH-TBB and HBB. Australia produced approximately 327,000 dry tonnes of biosolids in 2017, of which approximately 75% was beneficially utilized on farmland as a fertilizer. Based on these results, an estimated 440 kg of BDE-209 and 150 kg of DBDPE are applied to agricultural land via biosolids applications annually in Australia. This study provides the first account of NBFR concentrations in Australian biosolids.