Flame Retardants In Indoor Dust Research Articles

Evaluation of the oral bioaccessibility of legacy and emerging brominated flame retardants in indoor dust.

Indoor dust is the main source of human exposure to brominated flame retardants (BFRs). In this study, in vitro colon-extended physiologically-based extraction test (CE-PBET) with Tenax as a sorptive sink was applied to evaluate the oral bioaccessibility of twenty-two polybrominated diphenyl ethers (PBDEs) and seven novel BFRs (NBFRs) via indoor dust ingestion. The mean bioaccessibilities of two NBFRs pentabromotoluene (PBT) and 1,2-Bis(2,4,6-tribromophenoxy) ethane (BTBPE) were first proposed, reaching 36.0% and 26.7%, respectively. In order to maintain homeostasis of the gastrointestinal tract, 0.4g Tenax was added in CE-PEBT, which increased BFRs bioaccessibility by up to a factor of 1.4-1.9. The highest bioaccessibility of legacy PBDEs was tri-BDEs (73.3%), while 2-ethylhexyl-tetrabromo-benzoate (EHTBB), one of penta-BDE alternatives, showed the highest (62.2%) among NBFRs. The influence of food nutrients, liquid to solid (L/S) ratio, and octanol-water partition coefficient (Kow) on bioaccessibility was assessed. The oral bioaccessibility of BFRs increased with existence of protein or carbohydrate while lipid did the opposite. The bioaccessibilities of PBDEs and NBFRs were relatively higher with 200:1 L/S ratio. PBDEs bioaccessibility generally decreased with increasing LogKow. No significant correlation was observed between NBFRs bioaccessibility and LogKow. This study comprehensively evaluated the bioaccessibilities of legacy and emerging BFRs via dust ingestion using Tenax-assisted CE-PBET, and highlighted the significance to fully consider potential influencing factors on BFRs bioaccessibility in further human exposure estimation.

Occurrence and human exposure risk assessment of brominated and organophosphate flame retardants in indoor dust in Ha Noi, Viet Nam

Occurrence and human exposure risk assessment of brominated and organophosphate flame retardants in indoor dust in Ha Noi, Viet Nam

Legacy and alternative flame retardants in indoor dust from e-waste industrial parks and adjacent residential houses in South China: Variations, sources, and health implications

Many studies have elucidated health concerns of informal e-waste recycling activities, yet few has evaluated the effectiveness of the regulations as well as the human exposure risks to adjacent residents. Herein, legacy polybrominated diphenyl ethers (PBDEs), hexabromocyclododecane (HBCDs), and alternative organophosphate esters (OPEs) were investigated in indoor dust collected from three e-waste industrial parks and five adjacent villages located in south China. The levels and composition patterns varied significantly between workshop and home dust. BDE209 showed much higher (p < 0.01) concentrations in workshop dust versus home dust, while relatively comparable levels were found for OPEs and HBCDs. Principal component analysis revealed that OPEs and PBDEs were mainly related to home and workshop dust, respectively. Results strongly indicated that e-waste dismantling activities still contribute to a high burden of BDE209 to surrounding residents, whilst the sources of OPEs may also originated from household products, especially for TCEP. The estimated daily intakes (EDIs) via dust ingestion and dermal absorption for occupational worker and nearby toddlers were below available reference dose (RfD) values even at worst case scenario. This study highlights the significance of deca-BDEs rather than alternative OPEs in e-waste generated in China, which could provide scientific suggestions for policy formulation.

A nationwide survey of 20 legacy brominated flame retardants in indoor dust from China: continuing occurrence, national distribution, and implication for human exposure.

Despite the restrictions on polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecanes (HBCDDs), these chemicals are still ubiquitous environmental pollutants. In this study, we measured the concentrations and profiles of 17 PBDE congeners and 3 HBCDD isomers in indoor dust samples collected from 23 provinces and cities across China. The summed concentrations of PBDEs (Σ17PBDEs) ranged from 4.19 to 817ng/g, with an average of 171 ± 184ng/g. BDE-209 was the most abundant congener. The concentrations of HBCDDs ranged from 6.65 to 1335ng/g, with an average of 236 ± 324ng/g. Unlike commercial HBCDD formulations, α-HBCDD was the predominant isomer in the indoor dust samples analyzed. Geographical distributions showed that the concentrations of PBDEs and HBCDDs varied significantly among different regions. Higher PBDE and HBCDD levels were observed in samples from eastern coastal and economically developed regions. Further, we estimated the daily intakes of PBDEs and HBCDDs through the routes of dust ingestion and dust dermal absorption for different age groups. Dust dermal absorption is an unneglectable exposure pathway to PBDEs and HBCDs for the Chinese population. Among the age groups, infants had the highest exposure via dust dermal absorption, and toddlers had the highest exposure via dust ingestion. Compared with the threshold values, the exposure doses of PBDEs and HBCDDs are unlikely to pose significant health concerns for both infants and adults in China. This is the first national survey of PBDEs and HBCDDs in indoor dust samples across China after the restriction.

Legacy and Alternative Flame Retardants in Indoor Dust from E-Waste Industrial Parks and Adjacent Residential Houses in South China: Variations, Sources, and Health Implications

Legacy and Alternative Flame Retardants in Indoor Dust from E-Waste Industrial Parks and Adjacent Residential Houses in South China: Variations, Sources, and Health Implications

Legacy and alternative brominated, chlorinated, and organophosphorus flame retardants in indoor dust—levels, composition profiles, and human exposure in Latvia

Flame retardants (FRs) are additives used in consumer products to reduce flammability, even though they can easily contaminate the indoor environment. Since it is common for people in modern cities to spend up to 85% of time indoors, the quality of the indoor environment is critical for human health. In this study, polybrominated diphenyl ethers (PBDEs), organophosphorus flame retardants (OPFRs), emerging brominated flame retardants (EBFRs), and dechlorane-related compounds (DRCs) were measured in household dust samples (n=34) from Latvia, followed by human exposure assessment. Among all studied compounds, OPFRs showed the highest concentrations (1380-133,000ngg-1). Despite the phase-out of PBDEs, they were the second most significant flame retardants in the studied dust samples (468-25,500ngg-1) and the predominant compound was BDE-209. The concentrations of EBFRs were in the range of 120-7295ngg-1, with the most abundant contaminant being DBDPE, which is widely used as a substitute for the deca-BDE formulation. DRCs were the least common flame retardants in the Latvian indoor environments, with concentrations ranging 22.4-192ngg-1. Although the concentrations of specific FRs are known to vary between different countries, the levels and patterns observed in dust samples from Latvia were similar to those reported from Central Europe. Human exposure was evaluated as the estimated daily intake (EDI). The calculated exposure to most of the FRs was several orders of magnitude lower than the available reference dose (RfD) values.

Inhalation bioaccessibility and health risk assessment of flame retardants in indoor dust from Vietnamese e-waste-dismantling workshops

Although bioaccessibility testing is applied worldwide for appropriate chemical risk assessment, few studies have focused on the bioaccessibility of flame retardants (FRs), especially inhalation exposure. This study assessed inhalation exposure to FRs in indoor dust by workers at e-waste-dismantling workshops in northern Vietnam, by using modified simulated epithelial lung fluid (SELF) and artificial lysosomal fluid (ALF). The average mass concentrations of FRs were 130,000 ng/g for workplace dust (n = 3), 140,000 ng/g for floor dust (n = 3), and 74,000 ng/g for settled dust (n = 2), whereas the average bioaccessible concentrations of FRs were 1900, 1400, and 270 ng/g in the SELF condition and 2600, 770, and 490 ng/g in the ALF condition, respectively. Results clearly indicate that the bioaccessible concentrations of FRs are markedly lower than their mass concentrations. Tris(2-chloroethyl) phosphate (TCEP, ~19%), tris(2-chloroisopropyl) phosphate (TCIPP, ~35%), and tris(1,3-dichloroisopropyl) phosphate (TDCIPP, ~22%) showed comparably high bioaccessibility in both SELF and ALF conditions. In contrast, the bioaccessibility of tetrabromobisphenol A (TBBPA, ~20%) was high in the SELF condition, but not in the ALF condition. With regard to the test compounds' physicochemical properties, the inhalation bioaccessibility of FRs in both conditions increased as molecular weight or octanol–water partition coefficient decreased, and it decreased as water solubility decreased. Health risk assessment clearly indicated that the hazard quotient of FRs via inhalation exposure for workers in the e-waste-dismantling workshops was less than 1, suggesting that the inhalation exposure to FRs during indoor dismantling of e-waste at this site was negligible based on the current methodology of non-cancer health risk assessment used in this study.

Determination of organophosphate ester flame retardants in indoor dust and their potential health exposure risk

AbstractThis study was conducted to determine organophosphate ester compounds in indoor dust in Hanoi ‐ a populated city in Vietnam. In the study, the concentration and distribution of fifteen organophosphate esters (OPEs) were analyzed in indoor dust specimen. In general, the recorded total concentrations of OPEs in dust ranged from 2.7 to 14.1 μg/g and the average quantities varied from 0.2 to 1.0 μg/g. Particular, 100 % of survey samples were detected signals of OPEs, indeed, tris‐(2‐chloroisopropyl) phosphate (TCPP) and tris(2‐butoxyethyl)phosphate (TBEP) were two of the OPE substances, which their content accounted for the most in 15 analyzed compounds. OPE emission sources in indoor dust could be from locally used wide variety of consumer products and building materials in Hanoi houses. Moreover, tri‐m‐cresyl phosphate (TMCP) was practically observed in survey dust samples, and thus effects of traffic activities on OPEs contamination were not significant. Estimating human exposure to OPEs through directly absorbing foods was implemented and illustrated that this absorption route did not substantially affected adult and children health.

Evaluating the use of synchrotron X-ray spectroscopy in investigating brominated flame retardants in indoor dust.

Brominated flame retardants (BFRs) are commonly used in consumer products and they shed off these products and eventually build up in household dust. Polybrominated diphenyl ethers (PBDEs), in particular, are known endocrine-disrupting chemicals affecting various hormone syntheses. Portable X-ray fluorescence spectroscopy (XRF) is the most common non-destructive method in identifying BFRs in environmental samples. However, the method is insensitive to bromine speciation. Synchrotron-based XRF has been shown to have very low detection limits (< 1 μg/g) that is suitable for detecting BFRs and can be combined with X-ray absorption near-edge spectroscopy (XANES) to identify the bromine species present in the household dust. Twenty indoor dust samples were collected from rural homes in Newfoundland (Canada) to assess the use of synchrotron-based techniques to identify BFRs. Synchrotron-based XRF analysis identified bromine in all the samples, with concentrations ranging from 2-19 μg/g. XANES analysis identified organic-based bromine species in several samples that are likely BFRs based on the spectral line shape. The accuracy of using XANES to identify BFRs is highly dependent on the source and size of the dust samples. Therefore, for future research, it is important to take into account the sources of dust sample and to focus on fine dust particles.

The occurrence and distribution of polycyclic aromatic hydrocarbons, bisphenol A and organophosphate flame retardants in indoor dust and soils from public open spaces: Implications for human exposure

Global concern exists regarding human exposure to organic pollutants derived from public open spaces and indoor dust. This study has evaluated the occurrence of 18 polycyclic aromatic hydrocarbons (PAHs), 11 organophosphorus flame retardants (OPFRs) and bisphenol A (BPA). To achieve this, a new simple, efficient and fast multi-residue analytical method based on a fully automated pressurised liquid extraction (PLE) and subsequent quantification by gas chromatography coupled to electron ionization-mass spectrometry (GC-EI-MS) in selected ion monitoring (SIM) mode was developed. The developed method was applied to indoor dust (12 sampling households) and soil derived from two public open spaces (POSs). Among all compounds studied, PAHs were the most ubiquitous contaminants detected in POS soils and indoor dust although some OPFRs and BPA were detected in lower concentrations. An assessment of the incremental lifetime cancer risk (ILCR) was done and indicated a high potential cancer risk from the POS sites and some of the indoor dust sampled sites. However, key variables, such as the actual exposure duration, frequency of contact and indoor cleaning protocols will significantly reduce the potential risk. Finally, the ingestion of soils and indoor dust contaminated with OPFRs and BPA was investigated and noted in almost all cases to be below the USEPA reference doses.

A review on organophosphate flame retardants in indoor dust from China: Implications for human exposure

To investigate the status of organophosphate flame retardants (OPFRs) in indoor dust in China, published scientific studies were systematically collected and analyzed. The analysis revealed large variations among microenvironments, including offices (median: 14.59 μg/g) and e-waste workshops (median: 13.36 μg/g), with high levels of OPFRs contamination. Chlorinated organophosphate ester flame retardants (Cl-OPFRs) were the dominant OPFRs (52–75%) in most indoor dust samples; however, in e-waste workshops, aryl- and alkyl-OPFRs were the most abundant. As an alternative flame retardant to polybrominated diphenyl ethers (PBDEs), OPFRs concentrations have increased in recent years in indoor environments in China. Urban sources are of greatest concern: Shanghai (mean: 13.54 μg/g), Guangzhou (mean: 10.76 μg/g), and Beijing (mean: 9.37 μg/g) have high ΣOPFRs contamination levels in indoor dust. Compared to other countries, the OPFRs concentrations in indoor dust in all studied microenvironments from China (median: 8.81 μg/g) were low. The estimated daily intakes of ΣOPFRs by dust ingestion for adults and children were 2.12 and 11.06 ng/kg/body weight/day (average), respectively. Human exposure to OPFRs through the accidental intake of indoor dust does not pose a direct health risk to the Chinese population. However, indoor dust ingestion is an important route for human exposure to OPFRs.

Supramolecular solvent-based microextraction of aryl-phosphate flame retardants in indoor dust from houses and education buildings in Spain

Aryl-phosphate flame retardants (aryl-OPFRs) are flame retardants or plasticizers (among other functions) that can be found in a wide variety of products, from furniture and textiles to cars and electronic equipment. There is an increasing concern about the human exposure to these contaminants due to their ubiquity (as additives they can be easily released from the product to the environment) and potential toxicity. In this study, we investigated the presence of six representative aryl-OPFRs, two well-known aryl-OPFRs (triphenyl phosphate, TPHP and 2-ethylhexyl diphenyl phosphate, EHDPP), two novel aryl-OPFRs (cresyl diphenyl phosphate, CDP and isodecyl diphenyl phosphate, IDPP) and two oligomeric aryl-OPFRs [bisphenol A bis(diphenyl phosphate), BDP and resorcinol bis(diphenyl phosphate, RDP] in indoor dust from houses and education buildings from Spain. Sample treatment was carried out by a novel and simple procedure based on supramolecular solvents (SUPRAS) prior to LC-MS/MS analysis. The median Σaryl-OPFRs was two times higher in classrooms than in houses, being particularly high at University classrooms. The most abundant aryl-OPFR in houses was TPHP (median 497 ng·g−1) while EHDPP (median 407 ng·g−1) and IDPP (median 403 ng·g−1) were dominant in classrooms. This is the first study reporting IDPP, BDP and RDP in different education buildings.

Human exposure to legacy and emerging flame retardants in indoor dust: A multiple-exposure assessment of PBDEs

Human exposure to flame retardants (FRs) in indoor environments is a growing concern. In this study, the concentrations of polybrominated diphenyl ethers (PBDEs) and their alternatives, such as novel brominated flame retardants (NBFRs), dechlorane plus (DP), and organophosphate flame retardants (OPFRs), were measured in dust from indoor environments in Korea to investigate their occurrence, contamination profiles, and health risks. Legacy and emerging FRs were detected in dust samples, indicating widespread contamination of indoor environments. The concentrations of alternative FRs were higher in dust from offices compared with house dust, suggesting that office environments are major consumers of alternative FRs. Similar compositional profiles for indoor dust were found for PBDEs in different microenvironments and regions, while OPFR composition varied widely due to disparate applications. The estimated daily intakes of PBDEs, NBFRs, and OPFRs via dust ingestion were lower than the reference doses proposed by previous studies. A multiple-exposure assessment showed that dust ingestion was a major contributor to total PBDEs for toddlers and adults. However, major exposure pathways of BDEs 47 and 209 differed between toddlers and adults. Our study suggests that multiple exposure pathways should be considered in a comprehensive exposure assessment of PBDEs.

Polybrominated diphenyl ethers and novel brominated flame retardants in indoor dust of different microenvironments in Beijing, China

The occurrence levels of eight polybrominated diphenyl ethers (PBDEs) and four novel brominated flame retardants (NBFRs) were determined and compared in indoor dust from different microenvironments (21 homes, 23 offices and 16 day care centers) in Beijing, China. Concentrations of ∑8PBDEs in dust were 430–17,000 ng/g, 690–8600 ng/g, and 90–2300 ng/g for homes, offices, and day care centers, respectively, and were dominated by BDE-209. Concentrations of ∑4NBFRs ranged from 310 to 17,000 ng/g, 300 to 4300 ng/g, and not detected to 500 ng/g for homes, offices, and day care centers, respectively, and were dominated by bis(2-ethylhexyl)-3,4,5,6-tetrabromophthalate (BEH-TEBP) and decabromodiphenylethane (DBDPE) across microenvironments. The results showed an increasing detection and elevated concentration of NBFRs (especially BEH-TEBP), indicating that monitoring of NBFRs in dust samples should be of concern in future studies. A notable finding was that the BFR concentrations in dust samples from day care centers were generally one order of magnitude lower than those from homes and offices in the present study. This implies that previous estimates of toddler exposure via dust ingestion on data from homes may be overestimated. Concentrations of BDE-209 and ∑8PBDEs were found to be significantly higher in elevated surface dust than floor dust from day care centers. The estimates of daily intakes of BFRs via dust ingestion for Chinese adults and toddlers using Monte Carlo analysis were 2–5 orders of magnitude lower than the corresponding reference daily intakes.

Measurement of legacy and emerging flame retardants in indoor dust from a rural village (Kopawa) in Nepal: Implication for source apportionment and health risk assessment

Under the Stockholm Convention, signatory countries are obliged to direct source inventories, find current sources, and provide ecological monitoring evidence to guarantee that the encompassing levels of persistent organic pollutants (POPs) are declining. However, such monitoring of different types of POPs are to a great degree constrained in most developing countries including Nepal and are primarily confined to suspected source area/ densely populated regions. In this study, 9 polybrominated diphenyl ethers (PBDEs), 2 dechlorane plus (DPs), 6 novel brominated flame retardants (NBFRs) and 8 organophosphate ester flame retardants (OPFRs) were investigated in indoor dust from a rural area (Kopawa) in Nepal in order to evaluate their occurrence/level, profile, spatial distribution and their sources. Additionally, health risk exposure was estimated to anticipate the possible health risk to the local population. The results showed that OPFRs was the most abundant FR measured in the dust. The concentration of ∑8OPFRs was about 2, 3 and 4 orders of magnitude higher than the ∑6NBFRs, ∑9PBDEs, and ∑2DPs, respectively. Tris (methylphenyl) phosphate (TMPP) and Tris (2-ethylhexyl) phosphate (TEHP) were the most abundant OPFRs analyzed in the dust; while decabromodiphenyl ethane (DBDPE) exceeded among NBFRs. Likewise, 2,2′,3,3′,4,4′,5,5′,6,6′-decabromodiphenylether (BDE-209) was the most identified chemical among PBDEs. The total organic carbon (TOC) content in dust was significantly and positively connected with octa-BDEs (Rho = 0.615, p < 0.01), BTBPE (Rho = 0.733, p < 0.01), TPHP (Rho = 0.621, p < 0.01), TEHP (Rho = 0.560, p < 0.01) and TMPPs (Rho = 0.550, p < 0.01), while black carbon (BC) was either weakly related or not related, suggesting little or no impact of BC in the distribution of FRs. Principal component analysis indicated the contribution from commercial penta-, octa- and deca-BDEs formulation, the adhesive substance, food packaging and paints, and degradation of BDE-209 as the essential sources of FRs. Health risk exposure estimates showed that dermal absorption via dust as the primary route of FRs intake. The estimated daily exposure of PBDEs, NBFRs and OPFRs were 2–10 orders of magnitude lower than their corresponding reference dose (RfD), suggesting insignificant risk. However, other routes such as inhalation and dietary intake might still be significant in the case of Kopawa which should be tested in future.

Small-scale spatial variability of flame retardants in indoor dust and implications for dust sampling

Indoor dust is often used to evaluate levels of organic compounds indoors, particularly for compounds with indoor sources, such as flame retardants (FRs). Yet there are uncertainties about the type of information that can be obtained from indoor dust. This study reports detailed dust sampling to assess spatial variability in indoor dust concentrations, the relationship between FR sources and dust, and the implications when interpreting dust concentrations. Multiple dust samples were collected from a range of surface types in three large rooms: a residential flat, a university seminar room, and a university computer room. Samples were analysed for polybrominated diphenyl ethers (PBDEs), novel halogenated flame retardants (NFRs) and organophosphate esters (OPEs).FR levels in dust varied significantly between and within rooms. Levels typically ranged over one order of magnitude within a room, and up to four orders of magnitude for a few OPEs. The spatial distribution of FRs related (in some cases) to proximity to sources, surface properties, and dust surface loadings. Differences also existed between surface and floor dusts, e.g., the contribution of TBOEP to ∑OPEs was higher in floor than surface dust, which has implications for human exposure assessment; adults typically have more contact with elevated surfaces, while young children have greater contact with floor surfaces. Overall, significant spatial heterogeneity exists in indoor dust, even in seemingly homogeneous indoor spaces, thus hampering comparability between studies and locations when single samples are collected. Composite samples are strongly recommended to limit the influence of spatial heterogeneity.

Concentrations of legacy and novel brominated flame retardants in indoor dust in Melbourne, Australia: An assessment of human exposure

Polybrominated diphenyl ethers (PBDEs) and novel brominated flame retardants (NBFR) have been used in a range of polymers to inhibit the spread of fires but also have a propensity to migrate out of consumer materials and contaminate indoor dust. In this study, a total of 57 dust samples were collected from 12 homes, eight offices and eight vehicles in Melbourne, Australia and analysed for eight PBDEs (-28, -47, -99, -100, -153, -154, -183 and -209) and seven NBFRs (PBT, PBEB, HBB, EH-TBB, BEH-TEBP, BTBPE and DBDPE) to determine human exposure risks from dust ingestion. Samples were analysed using selective pressurized liquid extraction (S-PLE) and gas chromatography coupled to tandem mass spectrometry (GC–MS/MS). Legacy and replacement flame retardants were detected in all samples with overall ∑PBDE concentrations ranging from 120 to 1700,000 ng/g (median 2100 ng/g) and ∑NBFRs ranging from 1.1 to 10,000 ng/g (median 1800 ng/g). BDE-209 and DBDPE were the dominant compounds in dust samples, followed by congeners associated with commercial Penta-BDE formulations (-47, -99, -100, -153 and -154) and then EH-TBB of the FireMaster 550 and BZ-54 products. ∑Penta-BDE concentrations were elevated in office samples compared with homes and vehicles, while EH-TBB and BDE-209 measured higher concentrations in vehicles compared with their respective levels in homes and offices. Risk assessment estimates revealed the majority of exposure to occur in the home for both adults and toddlers in the City of Melbourne. Generally, body weight adjusted exposure to PBDEs and NBFRs was predicted to be 1 to 2 orders of magnitude higher for toddlers than adults. Estimated rates of BDE-47, -99, -153 and -209 ingestion were each 2 orders of magnitude or more below the USEPA's prescribed oral reference dose values (RfDs) for typical exposure scenarios. However, exposure rates for BDE-47 and -99 reached as high as 52 and 95% of RfDs, respectively, for adults and 4.4 and 7.4%, respectively, for toddlers in high exposure scenarios. This study provides the first wide-ranging survey of NBFRs in indoor dust from homes, offices and vehicles in Australia and offers further evidence of human exposure to legacy and novel brominated flame retardants via dust ingestion.

Impact of particle size on distribution and human exposure of flame retardants in indoor dust

The effect of dust particle size on the distribution and bioaccessibility of flame retardants (FRs) in indoor dust remains unclear. In this study, we analyzed 20 FRs (including 6 organophosphate flame retardants (OPFRs), 8 polybrominated diphenyl ethers (PBDEs), 4 novel brominated flame retardants (NBFRs), and 2 dechlorane plus (DPs)) in composite dust samples from offices, public microenvironments (PME), and cars in Nanjing, China. Each composite sample (one per microenvironment) was separated into 6 size fractions (F1–F6: 200–2000µm, 150–200µm, 100–150µm, 63–100µm, 43–63µm, and <43µm). FRs concentrations were the highest in car dust, being 16 and 6 times higher than those in offices and PME. The distribution of FRs in different size fractions was Kow-dependent and affected by surface area (Log Kow=1–4), total organic carbon (Log Kow=4–9), and FR migration pathways into dust (Log Kow>9). Bioaccessibility of FRs was measured by the physiologically-based extraction test, with OPFR bioaccessibility being 1.8–82% while bioaccessible PBDEs, NBFRs, and DPs were under detection limits due to their high hydrophobicity. The OPFR bioaccessibility in 200–2000µm fraction was significantly higher than that of <43µm fraction, but with no difference among the other four fractions. Risk assessment was performed for the most abundant OPFR-tris(2-chloroethyl) phosphate. The average daily dose (ADD) values were the highest for the <43µm fraction for all three types of dust using total concentrations, but no consistent trend was found among the three types of dust if based on bioaccessible concentrations. Our results indicated that dust size impacted human exposure estimation of FRs due to their variability in distribution and bioaccessibility among different fractions. For future risk assessment, size selection for dust sampling should be standardized and bioaccessibility of FRs should not be overlooked.

Presence of diphenyl phosphate and aryl-phosphate flame retardants in indoor dust from different microenvironments in Spain and the Netherlands and estimation of human exposure

Phosphate flame retardants (PFRs) are ubiquitous chemicals in the indoor environment. Diphenyl phosphate (DPHP) is a major metabolite and a common biomarker of aryl-PFRs. Since it is used as a chemical additive and it is a common impurity of aryl-PFRs as well as a degradation product, its presence in indoor dust as an additional source of exposure should not be easily ruled out. In this study, DPHP (and TPHP) are measured in indoor dust in samples collected in Spain and in the Netherlands (n=80). Additionally, the presence of other emerging aryl-PFRs was monitored by target screening. TPHP and DPHP were present in all samples in the ranges 169–142,459ng/g and 106–79,661ng/g, respectively. DPHP concentrations were strongly correlated to the TPHP levels (r=0.90, p<0.01), suggesting that DPHP could be present as degradation product of TPHP or other aryl-PFRs. Estimated exposures for adults and toddlers in Spain to TPHP and DPHP via dust ingestion (country for which the number of samples was higher) were much lower than the estimated reference dose (US EPA) for TPHP. However, other routes of exposure may contribute to the overall internal exposure (diet, dermal contact with dust/consumer products and inhalation of indoor air). The estimated urinary DPHP levels for adults and toddlers in Spain (0.002–0.032ng/mL) as a result of dust ingestion were low in comparison with the reported levels, indicating a low contribution of this source of contamination to the overall DPHP exposure. Other aryl-PFRs, namely cresyl diphenyl phosphate (CDP), resorcinol bis(diphenyl phosphate) (RDP), 2-ethylhexyl diphenyl phosphate (EDPHP), isodecyl diphenyl phosphate (IDP) and bisphenol A bis(diphenyl phosphate) (BDP), were all detected in indoor dust, however, with lower frequency.

Within-room and within-home spatial and temporal variability in concentrations of legacy and “novel” brominated flame retardants in indoor dust

To test the hypothesis that assessments of human exposure to PBDEs and NBFRs (PBEB, EH-TBB, BEH-TEBP, BTBPE and DBDPE) via dust ingestion should take into account spatial and temporal variability in dust contamination; 238 dust samples were collected from nine different rooms within three homes in Birmingham UK. In each room, three different dust samples were taken at monthly intervals for nine months, one sample from elevated surfaces and two samples from two different floor areas. Substantial within-room and within-home spatial variability in BFR concentrations was apparent between two floor areas and between different rooms due to the varying distances of sampled surfaces from potential BFR sources. With the exception of DBDPE, BFR concentrations in elevated surface dust exceeded significantly those in floor dust. Considerable within-room and within-home temporal variability in BFR concentrations was also apparent over a nine month sampling period. This is likely attributable to changes in room contents. Based on observed spatial and temporal variability, exposure estimates based on analysis of a single dust sample taken from one specific floor area at one specific point in time may not be entirely representative of human exposure in that room. Noticeable variability in BFR concentrations was also observed between colder and warmer seasons. In 13 out of 17 floor areas, concentrations of Σ8tri-deca-BDEs were higher in colder seasons, while those of Σ5NBFRs were higher in warmer seasons. Significant negative correlation was observed in two rooms between concentrations of BDE-99, Σ7tri-hepta-BDEs and BEH-TEBP and dust loading (g/m2).