Adrian Covaci

After the PBDE Phase-Out: A Broad Suite of Flame Retardants in Repeat House Dust Samples from California

Higher house dust levels of PBDE flame retardants (FRs) have been reported in California than other parts of the world, due to the state’s furniture flammability standard. However, changing levels of these and other FRs have not been evaluated following the 2004 U.S. phase-out of PentaBDE and OctaBDE. We analyzed dust collected in 16 California homes in 2006 and again in 2011 for 62 FRs and organohalogens, which represents the broadest investigation of FRs in homes. Fifty-five compounds were detected in at least one sample; 41 in at least 50% of samples. Concentrations of chlorinated OPFRs, including two (TCEP and TDCIPP) listed as carcinogens under California’s Proposition 65, were found up to 0.01% in dust, higher than previously reported in the U.S. In 75% of the homes, we detected TDBPP, or brominated “Tris,” which was banned in children’s sleepwear because of carcinogenicity. To our knowledge, this is the first report on TDBPP in house dust. Concentrations of Firemaster 550 components (EH-TBB, BEH-TEBP, and TPHP) were higher in 2011 than 2006, consistent with its use as a PentaBDE replacement. Results highlight the evolving nature of FR exposures and suggest that manufacturers continue to use hazardous chemicals and replace chemicals of concern with chemicals with uncharacterized toxicity.

Analytical developments and preliminary assessment of human exposure to organophosphate flame retardants from indoor dust

A new and efficient analytical method was developed and validated for the analysis of organophosphorus flame retardants (OPFRs) in indoor dust samples. This method involves an extraction step by ultrasonication and vortex, followed by extract clean-up with Florisil solid-phase extraction cartridges and analysis of the purified extracts by gas chromatography-mass spectrometry (GC-MS). Method recoveries ranged between 76 and 127%, except for volatile OPFRs, such as triethyl phosphate (TEP) and tri-(n-propyl) phosphate (TnPP), which were partially lost during evaporation steps. The between day precision on spiked dust samples was <14% for individual OPFRs, except for TEP, tri-iso-butyl phosphate (TiBP) and tri (2-butoxyethyl) phosphate (TBEP). Method limit of quantifications (LOQ) ranged between 0.02 μg/g (TnPP and tris(1-chloro-2-propyl phosphate (TCPP)) and 0.50 μg/g (TiBP). The method was further applied for the analysis of indoor dust samples taken from Flemish homes and stores. TiBP, TBEP and TCPP were most abundant OPFR with median concentrations of 2.99, 2.03 and 1.38 μg/g in house dust and of 1.04, 3.61, and 2.94 μg/g in store dust, respectively. The concentration of all OPFRs was at least 20 to 30 times higher compared to polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecanes (HBCDs). Estimated exposure to OPFRs from dust ingestion ranged for individual OPFRs between <1 and 50 ng/kg body weight for adults and toddlers, respectively. The estimated body burdens were 1000 to 100 times below reference dose (RfD) values, except for the scenario with high dust ingestion and high concentrations of TBEP in toddlers, where intake was only 5 times below RfD. Exposure of non-working and working adults to OPFRs appeared to be similar, but in specific work environments, exposure to some OPFRs (e.g. TDCPP) was increased by a factor >5.

Occurrence of a Broad Range of Legacy and Emerging Flame Retardants in Indoor Environments in Norway

This study investigates the occurrence of 37 organohalogen and organophosphate flame retardants (FRs) from Norwegian households (n = 48) and classrooms from two primary schools (n = 6). Around 80% of the targeted FRs were detected in air and dust from the sampling sites. The comparison of settled dust with floor dust revealed no statistical differences between median concentrations of the FRs (n = 12). Decabromodiphenyl ether and tris(2-butoxyethyl) phosphate showed the highest median floor dust concentrations in both environments. In the air samples, the highest concentrations were observed for 2,2,4,4-tetrabromodiphenyl ether and tris(1-chloro-2-propyl) phosphate. Remarkably, the emerging FR, 4-(1,2-dibromoethyl)-1,2-dibromocyclohexane, abbreviated as TBECH or DBE-DBCH, showed the highest indoor air concentrations reported in the literature (households, 77.9 pg/m(3) and schools, 46.6 pg/m(3)). Good Spearman correlations between the FR concentrations in dust and air (0.36 < R < 0.76) showed that is possible to estimate the concentrations in air from analyzed dust, or vice versa. Sources and pathways of exposure to FRs were assessed for the households. The main findings were that frequent vacuum cleaning resulted in lower FR concentrations in dust and that dermal contact with dust, for both children and mothers, was as important for the intake of organophosphate FRs as dust ingestion.

Novel brominated flame retardants in Belgian and UK indoor dust: Implications for human exposure

Concentrations of several novel brominated flame retardants (NBFRs) are reported in indoor dust samples from Belgian houses (n=39) and offices (n=6) and from day-care centers and schools in the West Midlands of the UK (n=36). Using a GC-ECNI/MS method, the following NBFRs were quantified: decabromodiphenyl ethane (DBDPE) (range <20-2470 ng g(-1)), 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE) (range <0.5-1740 ng g(-1)), tetrabromobisphenol A-bis(2,3-dibromopropylether) (TBBPA-DBPE) (range <20-9960 ng g(-1)), 2-ethylhexyl-2,3,4,5-tetrabromobenzoate (TBB) (range <2-436 ng g(-1)) and bis(2-ethylhexyl)-3,4,5,6-tetrabromophthalate (TBPH) (range <2-6175 ng g(-1)). Hexachlorocyclopentadienyl-dibromocyclooctane (HCDBCO), another NBFR, was below the detection limit of 2 ng g(-1) dust in all dust samples. No correlation was detected between concentrations of NBFRs and PBDEs. The ratio of TBB:TBPH in the dust samples ranged from 0.01 to 4.77 (average 0.42), compared to the ratio present in the commercial flame retardant product FM 550 (TBB:TBPH=4:1). Furthermore, no correlation was detected between concentrations in dust of TBB and TBPH. This may suggest different sources of these NBFRs, or similar sources but compound-specific differences in their indoor fate and transport. Exposure via dust ingestion was estimated for both adults and toddlers under low-end (5th percentile), typical (median), and high-end (95th percentile concentrations) scenarios. These were calculated assuming 100% absorption of intake dust and using mean dust ingestion (adults=20 mg d(-1); for toddlers=50 mg d(-1)) and high dust ingestion (adults=50 mg d(-1); for toddlers=200 mg d(-1)). Typical exposure with high dust ingestion estimates for adults were 0.01, 0.2, 0.01, 0.02 and 0.08 ng kg(-1) bw d(-1) and for toddlers 0.05, 1.9, 0.08, 0.4 and 1.12 ng kg(-1) bw d(-1) for BTBPE, DBDPE, TBB, TBPH and TBBPA-DBPE, respectively. Our results showed that, similar to PBDEs, toddlers have higher exposure to NBFRs than adults. This study documents the presence of NBFRs in indoor environments, and emphasizes the need to evaluate the health implications of exposure to such chemicals.

Multi-residue method for the determination of brominated and organophosphate flame retardants in indoor dust

A new method was optimized for the simultaneous determination of several flame retardants (FRs) in indoor dust, namely polybrominated diphenyl ethers (PBDEs), hexabromocyclododecanes (HBCDs), novel brominated flame retardants (NBFRs) and organophosphate ester flame retardants (OPFRs). The method was based on two previously validated analytical methods for NBFRs and OPFRs, which were combined in order to include even a large number of FRs. An ultrasonic extraction method and two-stage clean-up by adsorption chromatography was optimized using an indoor dust standard reference material (SRM 2584). The 1st cleanup step was essential for fractionation of analytes in the dust extracts, while the 2nd step was important for the further removal of interferences. Analysis of cleaned dust extracts was performed with gas chromatography electron impact ionization mass spectrometry for OPFRs, gas chromatography electron capture negative ionization mass spectrometry for PBDEs and NBFRs and liquid chromatography electrospray ionization tandem mass spectrometry for HBCDs. Method validation by matrix spiking demonstrated good accuracy ranging from 81 to 130%. Matrix effects were investigated by spiking sodium sulfate and dust with analyte standards. Typical recoveries ranged between 80 and 110% at both spiking levels, though occasional deviations were observed at low spiking concentrations. Precision between different days was generally below 24% relative standard deviation (RSD) at low concentrations and below 11% RSD at high concentrations. Method limits of quantification for BFRs ranged between 0.04 (BDE 28) and 17 ng/g (BDE 209), 6 ng/g for sum HBCDs, and for OPFRs between 10 (triphenyl phosphate) and 370 ng/g (tri-isobutyl phosphate). The method was applied to SRM 2585 and to a set of indoor dust samples from various countries. The newly developed method will be employed for the monitoring of human exposure via dust ingestion to phased-out and alternate FRs.

Levels and profiles of organochlorines and flame retardants in car and house dust from Kuwait and Pakistan: implication for human exposure via dust ingestion.

There are only few studies documenting indoor pollution in the Middle East and the Indian subcontinent. In present study, we have evaluated the occurrence of various organochlorines (OCs) and flame retardants (FRs) in dust from cars and houses of Pakistan and Kuwait. Polybrominated diphenyl ethers (PBDEs), novel brominated flame retardants (NBFRs), organophosphate FRs (PFRs), polychlorinated biphenyls (PCBs), and organochlorine pesticides (OCPs) were investigated in indoor dust from urban houses (N=15 per country) and cars (N=15 per country). PFRs were the major analytes in all four microenvironments, followed by PBDEs>NBFRs>OCPs>PCBs. For all classes of analytes, relatively lower levels were observed in car and house dust from Pakistan than Kuwait. Levels of ∑PBDEs, ∑NBFRs and ∑PFRs were higher in car dust, while ∑OCPs and ∑PCBs were higher in house dust from both countries. ∑PFRs occurred at average concentrations of 16,900, 87,900, 475, and 2500ng/g in Kuwaiti house and car, and Pakistani house and car dust, respectively. For both countries, the profiles of analytes in car dust were different from those in the house dust. Different exposure scenarios using 5th percentile, median, mean, and 95th percentile levels were estimated for adult, taxi drivers and toddlers. For Kuwaiti toddlers, assuming high dust intake and mean and 95th percentile concentrations, the values computed for ∑OCPs (1500ng/kg bw/day) were higher than RfD values, while for ∑PCBs (14.5ng/kg bw/day) it was only two-fold lower than the corresponding RfDs.

Distribution Patterns of Brominated, Chlorinated, and Phosphorus Flame Retardants with Particle Size in Indoor and Outdoor Dust and Implications for Human Exposure

Dust samples were collected in Beijing, China, from four different indoor microenvironments (office, hotel, kindergarten, and student dormitory) and one outdoor (road dust) microenvironment. These five composite samples were fractionated into 13 sequential size fractions and an individual fraction of <50 μm for further analysis. In the fractions of <50 μm, nine phosphorus flame retardants (∑PFRs), four novel brominated flame retardants (∑NBFRs), and two Dechlorane Plus isomers (DPs) showed the highest concentrations in hotel dust (124,000 ng g(-1)), dormitory dust (14,200 ng g(-1)), and kindergarten dust (231 ng g(-1)), respectively. Nevertheless, nine polybrominated diphenyl ethers (∑PBDEs) were the dominant flame retardants (FRs) (96% of total FRs) in road dust, with the maximum concentration of 23,700 ng g(-1), higher than in any indoor dust. The FR contamination varied strongly among different types of microenvironments, leading to high human exposure to various FRs. Concentrations of FRs did not increase constantly with a particle size decrease. Fractions with a particle size around 900, 100, and 10 μm could represent peak values, while valley values were commonly detected around fractions with a particle size around 40 μm. Large differences were found between indoor dust and road dust. In road dust, FRs were mainly enriched in fractions of <50 μm. The organic content of dust, FR application, and consequent abrasion processes of FR-containing materials might be the determinants of the FR concentrations. Volatilization and abrasion were considered to be important migration pathways for FRs. DPs and BDE-209 were sought to be mainly applied in abrasion-proof materials, while most phosphorus flame retardants (PFRs) were probably added in a large proportion in materials easy to wear.

Assessment of human exposure to indoor organic contaminants via dust ingestion in Pakistan.

UNLABELLEDnu2002 Ingestion of indoor dust has been acknowledged as an important route of exposure to organic contaminants (OCs). We investigated the presence of polybrominated diphenyl ethers (PBDEs), novel brominated flame retardants (NBFRs), organophosphate flame retardants (OPFRs), polychlorinated biphenyls (PCBs), and organochlorine pesticides (OCPs) in indoor floor dust from rural homes (N=31) and mosques (N=12) in Gujrat, Pakistan. Low concentrations were observed for most contaminants. OPFRs were the principle contaminants, with tri-(2-butoxyethyl)-phosphate (TBEP) and tri-phenyl-phosphate (TPP) having medians of 66 and 109 ng/g, respectively. PBDEs were only minor constituents in the investigated samples, with BDE 209 (median 40 ng/g) being the most important congener. Levels and profile of ∑PBDEs, ∑NBFRs, ∑HCHs, ∑DDTs, and ∑PCBs revealed no difference (P<0.05) between samples of dust from homes and mosques, indicating similar emission sources. Exposure scenarios using 5th percentile, median, mean, and 95th percentile levels were estimated for both adult and toddlers. Typical high-end, using median levels and high dust ingestion, exposure for adults were 0.02, 0.02, 0.03, <0.01, and 0.65 ng/kg bw/day and for toddlers 0.39, 0.45, 0.69, 0.01, and 15.2 ng/kg bw/day for ∑PBDEs, ∑NBFRs, ∑OCPs, ∑PCBs, and ∑OPFRs, respectively. To the authors knowledge, this is the first study to document the presence of indoor OCs in Pakistani dust.nnnPRACTICAL IMPLICATIONSnThis is the first report on the analysis of various contaminants in indoor dust from Pakistan. Some of these chemicals are currently being used in different consumer products. The study will help to further an understanding of the levels of different organic contaminants (OCs) in Pakistani indoor environments and will enlighten the generally ignored area of environmental pollution in Pakistan. Furthermore, studies based on animal models have shown that some of the analyzed chemicals can cause different types of chronic toxicities. However, our results showed that the levels of estimated exposure via dust ingestion for all chemicals were several orders of magnitude lower than their reference dose (RfD) values or than those reported in studies from Belgium, China, Singapore, and the UK (Ali et al., 2011a; Harrad et al., 2008; Tan et al., 2007a,b; Van den Eede et al., 2011a; Wang et al., 2010).

Organophosphate flame retardants in indoor dust from Egypt: implications for human exposure.

Organophosphate flame retardants (PFRs) have been proposed as alternatives for the phased out PBDE formulations. However, there exists no information on indoor dust contamination with PFRs in Africa. In this study, we report--for the first time--on levels and profiles of PFRs in dust samples from Egyptian houses (n = 20), offices (n = 20), cars (n = 20), and public microenvironments (PMEs; n = 11). Results revealed that PFR levels in Egyptian indoor dust are among the lowest reported worldwide. This may be attributed to less strict fire-safety standards and lack of regulatory actions against PBDEs. Triphenylphosphate was the only PFR detected in all samples with highest average concentration (386 ng g(-1)). While tris-2-chloroethyl phosphate, tris(1-chloro-2-propyl)phosphate and tris-1,3-dichloropropylphosphate showed higher detection frequency (DF = 69%, 57%, and 56%; average = 233, 229, and 144 ng g(-1), respectively), tri(2-butoxyexthyl)phosphate (37%; 294 ng g(-1)) displayed the second highest average concentration. Statistical analysis revealed significantly (P < 0.05) higher concentrations of ΣPFRs in cars (average = 1011 ng g(-1)) and PMEs (2167 ng g(-1)) than in houses (310 ng g(-1)) and offices (450 ng g(-1)). Estimated exposures of adults and toddlers to PFRs via dust ingestion were much lower than the reported reference doses, indicating no immediate health risk to the Egyptian population.

Analytical characteristics and determination of major novel brominated flame retardants (NBFRs) in indoor dust

A new method was developed and optimized for the detection of major “novel” brominated flame retardants (NBFRs), which included decabromodiphenyl ethane (DBDPE), 1,2-bis(2,4,6-tribromophenoxy) ethane (BTBPE), tetrabromobisphenol A-bis(2,3-dibromopropylether) (TBBPA-DBPE), 2-ethylhexyl-2,3,4,5-tetrabromobenzoate (TBB), bis(2-ethylhexyl)-3,4,5,6-tetrabromophthalate (TBPH) and hexachlorocyclopentadienyl-dibromocyclooctane (HCDBCO). Several solid phase sorbents were tested, and finally, a two-step cleanup procedure was established. The first step on activated silica was used to fractionate the dust extracts, while the second step on acidified silica (silica gel impregnated with sulphuric acid 44% w/w) and on Florisil®, respectively, was essential for advanced cleanup. High recoveries for NBFRs (range, 75–94%) were achieved. Analysis was performed by gas chromatography coupled with mass spectrometry in electron capture negative ionization using a DB-5ms (15xa0mu2009×u20090.25xa0mmu2009×u20090.1xa0μm) capillary column. Quantification of DBDPE, BTBPE and TBBPA-DBPE was based on ion m/z 79, while characteristic ions were used for quantification of TBB (m/z 359), HCDBCO (m/z 310) and TBPH (m/z 384). The method provided good repeatability; within- and between-day precision were ≤14% for all NBFRs. Method limits of quantification ranged between 1 and 20xa0ngxa0g−1; dust and NBFRs were not detected in blanks. The method was further applied to indoor dust (nu2009=u200921) collected from e-waste facilities in Thailand. Except for HCDBCO, all NBFRs were detected in the e-waste dust with concentrations up to 44,000 and 22,600xa0ngxa0g−1 DBDPE and BTBPE, respectively. The dust profile was dominated by DBDPE (50%)u2009>u2009BTBPE (45%)u2009>u2009TBBPA-DBPE (3%)u2009>u2009TBPH (1.9%)u2009>u2009TBB (0.1%). Significant correlations (pu2009<u20090.05) were found between the concentrations of BTBPE and BDE 183 or BDE 197 on the one hand, between TBPH and BDE 47 or BDE 99, and between DBDPE and BDE 209, on the other hand. Concentrations of TBB were not positively correlated with TBPH, which suggests different emission sources.