Polymeric Brominated Flame Retardants: Are They a Relevant Source of Emerging Brominated Aromatic Compounds in the Environment?

Abstract

A purge and trap method was used to study the release of brominated organic compounds from polymeric brominated flame retardants (BFRs), a relatively unknown class of flame retardant materials. Among the volatile brominated organics released, pentabromotoluene (PBTo), pentabromoethylbenzene (PBEB), and hexabromobenzene (HBB) were of particular interest because of their high potential to persist in the environment The impact of a thermal stress on the release of these compounds was assessed by applying different constant temperatures for one hour to a polymeric BFR sample. Release rates ranged between 22 +/- 2.1 ng g(-1) h(-1) for PBEB to 2480 +/- 500 ng g(-1) h(-1) for PBTo at room temperature. These rates of release reached 65 +/- 11 ng g(-1) h(-1) for PBEB and 42400 +/- 4700 ng g(-1) h(-1) for PBTo at 100 degrees C. This suggests that the compounding of thermoplastic polyesters done at high temperatures, up to 290 degrees C, could lead to the release of significant amounts of volatile brominated compounds in the environment when crude polymeric BFRs are used as flame retardants. To assess if this unsuspected source of volatile brominated compounds to the environment was relevant to support air concentrations in the Great Lakes area, air samples collected at Egbert (ON, Canada) were analyzed and PBTo, PBEB, and HBB were detected at low levels in some air samples (<0.01 to 0.09 pg/m3). As a second step, a Level III fugacity model was run using release rates of PBTo, PBEB, and HBB determined in this study. Results of the model indicated that prevailing PBEB and HBB air concentrations were not supported by their release from polymeric BFRs but by the use of these compounds as additive BFRs. However, these model predictions suffered from a lack of information on the actual use of polymeric BFRs. Hence, further work is needed to assess the release of potentially persistent brominated aromatic compounds from polymeric BFRs.

Emerging Brominated Flame Retardants in the Environment

“…HBBz was detected at low levels (0.02-0.09 pg/m 3 ) in four outdoor air samples collected at a rural/suburban location in Canada in 2005 [67]. A low concentration of HBBz (0.48 ng/g dw) was also found in a sample of outdoor dust (from atmospheric deposition) in Germany [68].…”

“…Polymeric BFRs could be possible sources of volatile brominated compounds even at low thermal stress. HBBz and other volatile brominated organics were released from a pentabromobenzyl acrylate oligomer (FR-1025, ICL Industrial Products, formerly Dead Sea Bromine Group, Israel) at room temperature [67]. The release rate increased as temperature increased (up to 100 C), suggesting that compounding of thermoplastics (done at higher temperatures) could lead to the release to the environment, although fugacity modeling indicated that concentrations found in outdoor air were better explained by its use as a flame retardant.…”

“…An additional identified source of PBEB emissions was from polymeric BFRs [67]. PBEB was released from the polymer at room temperature and the emissions increased several orders of magnitude when the polymer was exposed to thermal stress, a situation that normally occurs during compounding of thermoplastic polyesters.…”

Brominated Flame Retardants (BFR) in the Nordic Environment

“…However, preliminary modelling results indicate that the substance is used as an additive itself (Gouteux et al 2008). Concentrations in different matrices analysed are summarized in the Table 2.11.…”

A dynamic multimedia environmental and bioaccumulation model for brominated flame retardants in Lake Huron and Lake Erie, USA

“…Steady-state, nonequilibrium, level III fugacity models have been applied for both regional-scale assessment and near-field evaluation of chemical fate [8,9]. Nonequilibrium, nonsteady-state fugacity models (level IV) can account for time-varying emissions to environmental media to yield estimated recovery times for contaminated regions [10,11].…”