Microbial Reductive Debromination of Polybrominated Diphenyl Ethers (PBDEs)

Abstract

Polybrominated diphenyl ethers (PBDEs) are a class of widely used flame retardants that have recently been detected in environmental samples, diverse biota, human blood serum, and breast milk at exponentially increasing concentrations. Currently, little is known about the fate of these compounds, and in particular, about the microbial potential to degrade them. In this study, debromination of deca-BDE and an octa-BDE mixture is demonstrated with anaerobic bacteria including Sulfurospirillum multivorans and Dehalococcoides species. Hepta- and octa-BDEs were produced by the S. multivorans culture when it was exposed to deca-BDE, although no debromination was observed with the octa-BDE mixture. In contrast, a variety of hepta- through di-BDEs were produced by Dehalococcoides-containing cultures exposed to an octa-BDE mixture, despite the fact that none of these cultures could debrominate deca-BDE. The more toxic hexa-154, penta-99, tetra-49, and tetra-47 were identified among the debromination products. Because the penta-BDE congeners are among the most toxic PBDEs, debromination of the higher congeners to more toxic products in the environment could have profound implications for public health and for the regulation of these compounds.

Levels and distributions of PBDEs and PCBs in sediments of the Bohai Sea, North China

“…[32][33][34] In this study, the BDE 209 concentration was two orders of magnitude higher than other congeners. Thus the contribution of lower brominated congeners from BDE 209 degradation may not be negligible.…”

Polybrominated diphenyl ethers in surface soils from e‐waste recycling areas and industrial areas in South China: Concentration levels, congener profile, and inventory

“…Previous studies have reported on the photodegradation of BDE-209 to less brominated PBDE congeners in various solid matrices such as sediment, sand, and soil [34,35]. Microbial reductive debromination of BDE-209 and octa-BDEs mixtures under pure culture conditions has also been reported [36,37]. Furthermore, a recent study showed that BDE-209 may be degraded by microorganisms in anaerobic sediment to lessbrominated congeners, such as BDE-99, -47, and -66, and that BDE-99/-47 can also be transformed to BDE-28, BDE-17 by reductive debromination [38].…”

Current levels and composition profiles of PBDEs and alternative flame retardants in surface sediments from the Pearl River Delta, southern China: Comparison with historical data

“…S1 in the Supplemental material), which were similar to the profiles of the common technical penta-BDE mixtures . First, the contributions from BDE183 in the current sediments were significantly elevated compared with those collected in 2002 (p b 0.001), except for the Xijiang River and the PRE for two possible reasons: i) the release of PBDEs derived from the penta-BDE mixture decreased by a greater degree than BDE183 (a main ingredient of the octa-BDE mixture) after their regulation in 2006 in China, and/or ii) more BDE183 was generated from the microbial or photolytic debromination of highly brominated BDEs relative to other BDE congeners (Bezares-Cruz et al, 2004;He et al, 2006). Second, there was an apparent change (although not statistically significant for all cases) in the ratio of BDE47/(BDE47+ BDE99) between the current and previous (Fig.…”