A review of chamber experiments for determining specific emission rates and investigating migration pathways of flame retardants

A review of chamber experiments specific emission rates investigating migration pathways flame retardants Abstract: The widespread use of flame retardants (FRs) in indoor products has lead to their ubiquitous distribution within indoor microenvironments with many studies reporting concentrations in indoor air and dust. Little information is available however on emission of these compounds to air, particularly the measurement of specific emission rates, (SERs) or the migration pathways leading to dust contamination. Such knowledge gaps hamper efforts to develop understanding of human exposure. This review summarizes published data on SERs of the following FRs released from treated products: polybrominated diphenyl ethers (PBDEs), hexabromocyclododecanes (HBCDs), tetrabromobisphenol-A (TBBPA), novel brominated flame retardants (NBFRs) and organophosphate flame retardants (PFRs), including a brief discussion of the methods used to derive these SERs. Also reviewed are published studies that utilize emission chambers for investigations/measurements of mass transfer of FRs to dust, discussing the chamber configurations and methods used for these experiments. A brief review of studies investigating correlations between concentrations detected in indoor air/dust and possible sources in the microenvironment is included along with efforts to model contamination of indoor environments. Critical analysis of the literature reveals that the major limitations with utilizing chambers to derive SERs for FRs arise due to the physicochemical properties of FRs. In particular, increased partitioning to particulates due to their lower vapour pressures cause "sink" effects i.e. loss through absorption to chamber surfaces. Moreover, extended experiment times are often required at room temperature conditions for formation of steady state conditions inside the chamber. The limitations of chamber experiments are discussed as well as their potential Abstract The widespread use of flame retardants (FRs) in indoor products has lead to their ubiquitous 23 distribution within indoor microenvironments with many studies reporting concentrations in 24 indoor air and dust. Little information is available however on emission of these compounds 25 to air, particularly the measurement of specific emission rates, (SERs) or the migration 26 pathways leading to dust contamination. Such knowledge gaps hamper efforts to develop 27 understanding of human exposure. This review summarizes published data on SERs of the 28 following FRs released from treated products: polybrominated diphenyl ethers (PBDEs), 29 hexabromocyclododecanes (HBCDs), tetrabromobisphenol-A (TBBPA), novel brominated 30 flame retardants (NBFRs) and organophosphate flame retardants (PFRs), including a brief 31 discussion of the methods used to derive these SERs. Also reviewed are published studies that 32 utilize emission chambers for investigations/measurements of mass transfer of FRs to dust, 33 discussing the chamber configurations and methods used for these experiments. A brief 34 review of studies investigating correlations between concentrations detected in indoor air/dust 35 and possible sources in the microenvironment is included along with efforts to model 36 contamination of indoor environments. Critical analysis of the literature reveals that the major 37 limitations with utilizing chambers to derive SERs for FRs arise due to the physicochemical 38 properties of FRs. In particular, increased partitioning to particulates due to their lower 39 vapour pressures cause "sink" effects i.e. loss through absorption to chamber surfaces. 40 Moreover, extended experiment times are often required at room temperature conditions for 41 formation of steady state conditions inside the chamber. The limitations of chamber 42 experiments are discussed as well as their potential for filling gaps in knowledge in this area. 46