A comparison of the fish bioconcentration factors for brominated flame retardants with their nonbrominated analogues

Flame retardants (FR) play a significant role in reducing the flammability of many consumer products. On a volume basis, approximately 25% of the FRs in use today utilize bromine as the active flame-retarding moiety. Their applications are those requiring high FR performance or in resins needing an FR that is active during the gas phase. Laboratory fish bioconcentration factors (BCFs) for 11 brominated FRs (BFRs) or their components were compared with those for their nonbrominated analogues. Bioconcentration, defined here as a BCF of greater than 1,000, was not observed in those brominated molecules examined with molecular weights of 700 or greater. These included the decabromodiphenyl oxide and octabromodiphenyl oxide commercial products, ethane 1,2-bis(pentabromophenyl), ethylene bis-tetrabromophthalimide, and decabromobiphenyl. Tetrabromobisphenol A, with a molecular weight of less than 700, also did not bioconcentrate. This likely relates to the ease with which it is metabolized and eliminated. Within the BFR class of polybrominated diphenyl oxides/ethers, the BCFs for those congeners with molecular weights of between approximately 450 and 700 varied with the number and position of the bromine atoms. The BCF of hexabromocyclododecane appeared to be related to its cyclododecane substructure, not to its bromine content. Bioconcentration was not a characteristic feature of the BFRs examined here.