Trophodynamics of Hexabromocyclododecanes and Several Other Non-PBDE Brominated Flame Retardants in a Freshwater Food Web

Several currently used non-polybrominated diphenyl ether (PBDE) brominated flame retardants (BFRs), including hexabromocyclododecanes (HBCDs), 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE), decabromodiphenyl ethane (DBDPE), hexabromobenzene (HBB), pentabromoethylbenzene (PBEB), and pentabromotoluene (PBT), are examined in the components of a freshwater food web from an electronic waste recycling site, South China. All these BFRs are detectable in the food web, with average concentrations of 13.9−868, 1.71−518, < 3.8−338, 197−3099, 3.98−25.6, and 1.20−3.60 ng/g lipid wt for HBCDs, BTBPE, DBDPE, HBB, PBEB, and PBT, respectively. Food web magnification is observed for (+)-α-, (−)-α-, (±)-α-, and total HBCDs, and HBB, with trophic magnification factors (TMFs) of 2.22, 2.18, 2.19, 1.82, and 1.46, respectively; whereas there is trophic dilution of BTBPE and PBT through the food web. The TMFs for (+)-α-, (−)-α-, and (±)-α-HBCDs are comparable to those of PBDEs detected previously in the same food web. Biota samples show a shift from γ- toward α-HBCD compared with the suspended particles, sediment, and HBCD technical mixtures, with a significant increase of α-HBCD on ascending trophic levels. Except for α-HBCD in suspended particles and sediment, all the HBCD enantiomers detected are nonracemic in the environmental matrix. In biota, nonracemic residues of α-HBCD were observed in mud carp and crucian carp; β-HBCD in prawn, mud carp, and crucian carp; and γ-HBCD in water snake, with preferences for (+)-α-, (−)-β-, and (+)-γ-HBCDs.