Concentrations of polybrominated diphenyl ethers (PBDEs) and other brominated flame retardants (BFRs) have been rapidly increasing in fish, birds, sediments, indoor environments, and humans, but emission sources and exposure pathways of these pollutants remain poorly understood. The many BFR-containing materials in buildings constitute a large reservoir of these compounds, and in-use releases from this reservoir may be a significant environmental source. To estimate in-use releases from building materials and contents in residences, we monitored 12 houses and garages in two seasons and combined measurements of BFRs in air and settled dust, air exchange rates, and other information in an approach that utilized the building as a "natural" test chamber. Results were scaled to provide a first estimate of aggregate emission rates from U.S. houses. PBDE releases total about 4 microg h(-1) per house or 20 ng m(-2) h(-1), and U.S. houses and garages collectively release about 4100 kg y(-1). Most of these releases are settled floor dust, but about 20% are released directly to the ambient environment via airborne vapor and particulate matter. These screening-level estimates are subject to considerable uncertainty, but they have an advantage in that they reflect real-world conditions based on mass balance calculations.
"PBDEs were calculated in this study which were comparable to PBDE emission factors of 2 × 10 −7 to 7.1 × 10 −7 yr −1 (g · yr −1 per g in TV rear cover) estimated by Sakai et al. (2006) for migration to dust inside TV cabinets. Appreciable attempts have been made to estimate (back-calculate) PBDE emissions from measured indoor concentrations either using models based on simple equations (Batterman et al., 2009) or by applying more sophisticated mass-balance modelling methods (Zhang et al., 2009, 2011). Even though model predictions were in some cases comparable to experimentally derived values, associated uncertainties with model formulations indicate the need for further combined chamber-modelling studies. "
[Show abstract][Hide abstract] ABSTRACT: This review explores the existing understanding and the available approaches to estimating the emissions and fate of semi-volatile organic compounds (SVOCs) and in particular focuses on the brominated flame retardants (BFRs). Volatilisation, an important emission mechanism for the more volatile compounds can be well described using current emission models. More research is needed, however, to better characterise alternative release mechanisms such as direct material-particle partitioning and material abrasion. These two particle-mediated emissions are likely to result in an increased chemical release from the source than can be accounted for by volatilisation, especially for low volatile compounds, and emission models need to be updated in order to account for these. Air-surface partitioning is an important fate process for SVOCs such as BFRs however it is still not well characterised indoors. In addition, the assumption of an instantaneous air-particle equilibrium adopted by current indoor fate models might not be valid for high-molecular weight, strongly sorbing compounds. A better description of indoor particle dynamics is required to assess the effect of particle-associated transport as this will control the fate of low volatile BFRs. We suggest further research steps that will improve modelling precision and increase our understanding of the factors that govern the indoor fate of a wide range of SVOCs. It is also considered that the appropriateness of the selected model for a given study relies on the individual characteristics of the study environment and scope of the study.
Science of The Total Environment 02/2014; 491. DOI:10.1016/j.scitotenv.2014.02.005 · 4.10 Impact Factor
"Several studies have involved the investigation of temporal variation of PBDE occurrence in indoor dust (Allen et al., 2008; Batterman et al., 2009; Harrad et al., 2008a; Vorkamp et al., 2011; Yu et al., 2012), of which only one study was specifically devoted to this topic (Muenhor and Harrad, 2012). Yet, these investigations were subjected to considerable uncertainty, because most of their conclusions were based on limited and discontinuous sampling sizes. "
[Show abstract][Hide abstract] ABSTRACT: This study documents the temporal variability in concentrations of flame retardants (FRs) in floor dust from three offices in Beijing, China. Dust from Office A (OAD) was collected weekly from March to August, 2012, and sampling of dust from Office B and C (OBD and OCD) was conducted fortnightly (each two weeks) from March to December 2012. With intensive and continuous sampling, we report for the first time on clear and coherent temporal trends of polybrominated diphenyl ethers (PBDEs), novel brominated flame retardants (NBFRs) and phosphorus flame retardants (PFRs) in indoor dust. The observed mean concentrations of ∑9PBDEs, ∑4NBFRs and ∑9PFRs, were 554, 11,100 and 128,000ngg(-1) in OAD; 7560, 5000 and 17,300ngg(-1) in OBD; and 4750, 3550 and 17,200ngg(-1) in OCD, respectively. With exception of PBDEs, concentrations of FRs were elevated in OAD than in OBD and OCD. Two to ten-fold variations were observed between the minimum and maximum concentrations of FRs in the same office, indicating that the sampling moment exerts a substantial influence on the level of FR contamination. Different seasonality was distinctively found between BFRs and PFRs. Except for a few occasional abnormal values, BFR levels in office dust were generally constant among different seasons. The abundance rank order for PFRs was: winter>autumn>summer, with peak values occurring in late winter and early spring. This pattern may be attributable to the fact that PFRs are more sensitive to temperature changes compared to PBDEs and NBFRs owning to their higher volatilities. The absence of significant seasonal variation for BFR concentrations in indoor dust compared to outdoor air and dust concentrations is also discussed.
Environment international 01/2014; 65C:100-106. DOI:10.1016/j.envint.2013.12.011 · 5.56 Impact Factor
"These findings for Octa-BDE are consistent with those of Batterman et al. (2009), who reported that concentrations of PBDEs in indoor dust collected in different seasons in a study of 12 US homes displayed little consistency. The study of Vorkamp et al. (2011), evaluated temporal variability in concentrations of PBDEs 183 and 209 in samples from the same houses taken three months apart. "
[Show abstract][Hide abstract] ABSTRACT: Within-house and within-room spatial temporal variability in PBDE contamination of indoor dust may influence substantially the reliability of human exposure assessments based on single point samples, but have hitherto been little studied. This paper reports concentrations of PBDEs 17, 28, 47, 49, 66, 85, 99, 100, 153, and 154 in indoor dust samples (n=112) from two houses in Birmingham, UK. To evaluate within-house spatial variability, four separate rooms were sampled in house 1 and two separate rooms sampled in house 2. Up to four different 1 m² areas in the same room were sampled to evaluate within-room spatial variability, and for all studied areas, samples were taken for eight consecutive months to evaluate temporal and seasonal variability. Concentrations of ΣPBDEs in individual samples from house 1 varied between 21 and 280 ng g⁻¹; while the range of concentrations in house 2 was 20-1000 ng g⁻¹. This indicates that where and when a sample is taken in a house can influence substantially the contamination detected. In one room, concentrations of PBDEs in an area located close to putative PBDE sources exceeded substantially those in an area 2m away, with marked differences also observed between two areas in another room. Substantial within-room spatial differences in PBDE concentrations were not discernible in the other rooms studied. Concentrations of PBDEs in the majority of rooms within the same houses were not markedly different between rooms. Nevertheless, large differences were observed between PBDE concentrations detected in two rooms in the same house in both houses studied. In one instance, this is hypothesised to be attributable to the presence of a carpet in one room and bare wooden floor in another, but firm conclusions cannot be drawn. Within-room temporal (month-to-month) variability was substantial (relative standard deviations for ΣPBDEs=15-200%). In some rooms, the introduction and removal of putative sources like a TV and a bed, appeared to exert a discernible influence on PBDE concentrations. PBDE concentrations in spring and summer were not markedly different from those observed in autumn and winter. Possible dilution of PBDE concentrations in dust at higher dust loadings (g dust per m² floor surface) was investigated in a small number of rooms, but no firm evidence of such dilution was evident.
Environment international 06/2012; 47:23-7. DOI:10.1016/j.envint.2012.06.001 · 5.56 Impact Factor
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