A meta-analysis of recent data on UK environmental levels of POP-BFRs in an international context: Temporal trends and an environmental budget

Abstract

Abstract This study collates and synthesises UK data on environmental levels of POP-BFRs published between 1999 and March 2015. Target POP-BFRs are: the polybrominated diphenyl ether (PBDE) formulations Penta-BDE, Octa-BDE, and Deca-BDE (the latter as a candidate Stockholm Convention POP), as well as hexabromocyclododecane (HBCDD). Environmental compartments covered include: sediments (freshwater and marine), atmospheric deposition (both measured directly and inferred from sediment core data), soil, herbage, outdoor air, indoor air, indoor dust, freshwater (rivers and lakes), human tissues (blood serum and milk), wildlife, and the human diet. Temporal trends in contamination were examined for evidence of environmental responses to regulatory and voluntary actions banning/restricting the manufacture and use of POP-BFRs. Good evidence exists that – with some exceptions – concentrations of Penta-BDE congeners like BDEs-47 and 99 have responded well to the use restrictions introduced in the mid-2000s. However, it appears that human body burdens of these contaminants do not appear to have responded in a similar way, as levels in UK human milk in 2010–2012, are not discernibly different to those reported in 2002–03. The evidence for HBCDD and BDEs-183 and 209 is less abundant, but signs exist that absolute concentrations of BDE-183 are falling in the UK environment. With respect to BDE-209, evidence from analysis of lake sediment core and UK diet samples, suggests that levels have yet to respond discernibly to the more recent curbs on manufacture and use of Deca-BDE. The limited evidence for HBCDD is strongly consistent with a declining trend in environmental contamination with this chemical. Broadly, examination of the UK database in an international context, suggests UK levels are generally within the range of those found in other industrialised countries. Interestingly, while UK concentrations of BDE-209 in abiotic matrices such as indoor dust, are at the high end of those reported globally; concentrations in UK human milk are amongst the lowest reported to date. This suggests that the bioavailability of BDE-209 from indoor dust is likely very low. An environmental budget was estimated for the UK burden of POP-BFRs. As with previous comparable exercises for polychlorinated biphenyls (PCBs) and chlorinated dioxins, the majority (>90%) of the UK burden of POP-BFRs resides in soil. Moreover, the POP-BFR burden identifiable as present in the UK environment is much lower than data on production and use of POP-BFRs in Europe. This may be explained by POP-BFRs: (a) undergoing environmental transport away from the UK; (b) undergoing environmental degradation; (c) remaining in use; and (d) entering the waste stream. While the UK database appears relatively strong for some environmental compartments and POP-BFRs – e.g. BDEs-47 and -99 are well-characterised in the human diet, indoor air/dust, and human milk – substantial gaps exist for BDE-209 and HBCDD in air (indoor and outdoor), herbage, and soil.