Article pubs.acs.org/est
Human Exposure to Legacy and Emerging Halogenated Flame Retardants via Inhalation and Dust Ingestion in a Norwegian Cohort Joo Hui Tay,*,† Ulla Sellström,† Eleni Papadopoulou,‡ Juan Antonio Padilla-Sánchez,‡ Line Småstuen Haug,‡ and Cynthia A. de Wit† †
Department of Environmental Science and Analytical Chemistry (ACES), Stockholm University, SE-106 91 Stockholm, Sweden Department of Environmental Exposure and Epidemiology, Norwegian Institute of Public Health (NIPH), Lovisenberggata 8, N-0403 Oslo, Norway
‡
S Supporting Information *
ABSTRACT: In this study, we estimated human exposure to polybrominated diphenyl ethers (PBDEs), hexabromocyclododecanes (HBCDDs), and several emerging flame retardants (EFRs) via inhalation and dust ingestion. Sixty indoor stationary air samples, 13 personal air samples, and 60 settled dust samples were collected from a Norwegian cohort during winter 2013. PBDEs showed the highest median concentration in dust (1200 ng/g), followed by EFRs (730 ng/g) and HBCDDs (190 ng/g). The PBDE concentrations in dust were mainly driven by BDE-209 and those of EFRs by bis(2ethylhexyl) tetrabromophthalate. EFRs predominated in stationary air samples, with 2-ethylhexyl 2,3,4,5-tetrabromobenzoate and 4-(1,2-dibromoethyl)-1,2-dibromocyclohexane having the highest median concentrations (150 and 25 pg/m3 (sum of α- and β-isomers), respectively). Different profiles and concentrations were observed in personal air samples compared to the corresponding stationary air samples. In relation to inhalation exposure, dust ingestion appears to be the major exposure pathway to FRs (median total exposure 230 pg/kg bw/d, accounting for more than 65% of the total exposure) for the Norwegian cohort. The calculated exposure due to air inhalation was substantially lower when the stationary air concentrations were used rather than personal air concentrations (43 pg/kg bw/d versus 130 pg/kg bw/d). This suggests that other exposure situations (such as outdoors or in offices) contributed significantly to the overall personal exposure, which cannot be included by using only a stationary air sampling technique. The median and 95th percentile exposures for all target FRs did not exceed the reference dose.
■
INTRODUCTION Flame retardants (FRs) are chemicals added to a broad range of household products such as textiles, electrical and electronic equipment, furniture, and building insulation to meet flammability standards. Most of these chemicals, such as polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecanes (HBCDDs), are additives which are more likely to leach from the finished products during use and tend to partition into various compartments, through direct dispersion in indoor air, adsorption, and/or transfer to dust via physical processes such as abrasion or weathering. As a result of persistence, bioaccumulation, and potential toxicity effects,1−5 two of the technical formulations of PBDEs (PentaBDE and OctaBDE) and HBCDDs were added to the list of chemicals for elimination under the Stockholm Convention.6 The third formulation, DecaBDE, is currently under review for listing on the Stockholm Convention and has been banned in Norway since 2008.7 Recently, the European Union has implemented measures to regulate DecaBDE as a completely new entry under Annex XVII of REACH, which will be implemented in phases starting March 2, 2019.8 The restrictions on these FRs © XXXX American Chemical Society
has resulted in a need for their replacement with other chemicals, known as emerging flame retardants (EFRs). Applications, uses, and production volumes of some important EFRs can be found in the Supporting Information (Table S1). Concentrations of FRs in air and dust have been used to estimate human exposure from air inhalation and dust ingestion in various countries.9−14 Most of the studies have extrapolated the human inhalation exposure from indoor stationary air data, and only a few have compared personal air (air close to a person’s face) and stationary air data. Significantly higher concentrations of PBDEs were detected in personal air samples compared to stationary air samples from people’s homes15 and occupational settings.16,17 These studies indicate that stationary indoor air concentrations from the home might not fully represent what people are exposed to, because of time−activity patterns in several different microenvironments. Received: April 24, 2017 Revised: June 16, 2017 Accepted: June 16, 2017
A
DOI: 10.1021/acs.est.7b02114 Environ. Sci. Technol. XXXX, XXX, XXX−XXX
Article
Environmental Science & Technology
Dust Samples. The dust extracts were fractionated on SPE columns containing 2 g of silica essentially according to Sahlström et al.20 but with one modification: fraction 3 was eluted with 10 mL of EtOAc instead of 50% diethyl ether in nHex (v/v) to also collect TBBPA (Figure S2). Fraction 3 was then divided into two equal parts (fractions 3A for HBCDDs and 3B for TBBPA). Fractions 1 and 3A were further cleaned up with concentrated sulfuric acid, while fraction 2 was cleaned up on an aminopropyl (NH2) column according to Sahlström et al.20 Fraction 3B (containing TBBPA) was solvent exchanged to n-Hex and extracted with a 0.01 M sodium hydroxide (NaOH) water solution. The organic phase was discarded, the water phase acidified with 1 N sulfuric acid, more n-Hex added, and TBBPA re-extracted from the water phase. More details are given in the Supporting Information. Instrumental Analysis. Fractions I and II were analyzed for PBDEs and EFRs by GC−MS, with the mass spectrometer run in ECNI mode, on the basis of a previously described method (Sahlström et al.20). HBCDDs and TBBPA were analyzed essentially according to Sahlström et al.20 using UPLC coupled to tandem-quadrupole MS using electrospray ionization (ESI) in negative mode. Details on the instrumental parameters (Table S4) and methods are described in the Supporting Information. Quality Assurance (QA)/Quality Control (QC). All amber glassware was heated to 450 °C for 4 h and rinsed with acetone before use. UV filters were mounted on windows, and light fixtures in the laboratory and samples were covered with aluminum foil whenever possible to prevent photodegradation of the analytes and/or possible contamination from laboratory facilities. The sampling trains were cleaned by ultrasonication in ethanol and water (30:70, v/v) and air-dried. PUF plugs were precleaned by Soxhlet extraction for 24 h in DCM and 24 h in acetone. GFFs were precleaned by being heated in an oven at 450 °C for 24 h. Air field blanks were collected by loading the sampling trains with PUF plugs and a GFF and attaching them to the pump for a few seconds without turning the pump on. Dust field blanks were collected by placing the filter cassette into the holder and attaching it to the vacuum cleaner without turning the vacuum cleaner on. Twelve field blanks (BFs) and 4 laboratory (solvent) blanks (BLs) were processed together with stationary air samples (3 BFs and 1 BL per batch of 16 samples). For personal air samples, 13 BFs and 2 BLs were analyzed together with the 13 samples. Blank correction was performed by subtracting the mean amount detected in the BFs from the same batch. No FRs were detected above the BF levels in the BL. Standard reference material (SRM 2585, “organic contaminants in house dust”) from the National Institute of Standards and Technology (NIST; Gaithersburg, MD) was used as the QC sample for the dust analyses. Four BFs and one QC sample were analyzed per batch of 20 dust samples. PBDE and EFR concentrations in SRM dust obtained were in agreement with the certified values and those reported in the literature (Table S5, Supporting Information). The recoveries of 13C-labeled surrogate standards were satisfactory (Table S6, Supporting Information). Determination of method detection and quantification limits (mLOD and mLOQ) was performed according to Newton et al.21 In short, the mLODs and mLOQs for analytes present in the blanks were set to the mean blank values plus 3 and 5 times the standard deviation of the blanks, respectively. For analytes not present in the blanks, LOQ was defined as a signal/noise ratio of 10 and LOD as LOQ divided by 3. The mLODs and
The aim of the present study was to estimate human exposure to FRs through dust ingestion and air inhalation in a Norwegian cohort. To also study the comparability of indoor air to personal air, simultaneous sampling of stationary air and personal air was done for a subsample of the participants.
■
MATERIALS AND METHODS Information about the chemicals and materials used in this study can be found in the Supporting Information. Sample Collection. Settled dust and stationary air samples were collected from the living room of 61 households in Norway between November 2013 and April 2014. In parallel, personal air samples from adults residing in these homes were collected. Thirteen of the personal air samples were available for this study (the other personal air samples went to analysis of other analytes elsewhere). Stationary air was sampled in the living room for 24 h using a low-volume active air pump (Leland Legacy, SKC Inc., Eighty Four, PA) attached to four parallel sampling trains each containing two polyurethane foam (PUF) plugs and one glass fiber filter (GFF) at a flow rate of 12 L/min, giving a total sample volume of ∼17 m3. Personal air was also sampled for 24 h with a low-volume active air pump (SKC pump 224-PCMTX4, SKC Inc., Eighty Four, PA) at a flow rate of 1 L/min (∼1.4 m3/d) with only one sampling train containing PUF plugs and a GFF. After the air sampling was complete, settled dust was collected from elevated surfaces (e.g., tables, shelves) in the same living room area using a vacuum cleaner with a dust sampling filter connected to it (cellulose filters in styrene−acrylonitrile holders, KTN AB, Bålsta, Sweden). Air and dust field blanks were also collected. The participants also answered a questionnaire regarding the characteristics of their home, such as information on building and consumer goods. The sampling procedures are described in detail elsewhere.18 Extraction. Before extraction, samples were spiked with isotopically labeled surrogate standards of BDE-155, -197, and −209, Dechlorane Plus (syn- and anti-DDC-CO), 1,2-bis(2,4,6tribromophenoxy)ethane (BTBPE), α-, β-, and γ-HBCDD, 2ethylhexyl 2,3,4,5-tetrabromobenzoate (EH-TBB), bis(2-ethylhexyl) 3,4,5,6-tetrabromophthalate (BEH-TEBP), and tetrabromobisphenol A (TBBPA). Native and isotopically labeled standards used are given in Tables S2 and S3 in the Supporting Information. All samples were extracted with dichloromethane (DCM) in an ultrasonic bath for 30 min. For stationary air samples, 18 mL of DCM was used, and for personal air samples and dust, 10 mL of DCM was used. After extraction, the supernatant was transferred to another test tube, the extraction procedure was repeated once, and the extracts were combined. The solvent volume was then reduced to 1 mL under a gentle stream of nitrogen, and the solvent changed to n-hexane (nHex). Cleanup. Air Samples. The raw sample extract was fractionated into three fractions on a silica SPE column (Agilent Bond Elut-SI, 500 mg/3 mL cartridges) according to Ionas and Covaci19 (Figure S1, Supporting Information). Fraction I from the silica column was further cleaned up by treatment with concentrated sulfuric acid and analyzed for PBDEs and most of the EFRs. Fraction II was split in two and analyzed separately for HBCDDs (with ultraperformance liquid chromatography−mass spectrometry (UPLC−MS)) and BEHTEBP (with gas chromatography−electron capture negative ion mass spectrometry (GC−ECNI-MS)). TBBPA was eluted in fraction III with 8 mL of ethyl acetate (EtOAc). B
DOI: 10.1021/acs.est.7b02114 Environ. Sci. Technol. XXXX, XXX, XXX−XXX
Article
Environmental Science & Technology Table 1. FR Concentrations in Settled Dust and Stationary and Personal Air Samplesa stationary air concn (pg/m3, n = 60)
settled dust concn (ng/g, n = 60) GM
min
median
max
DF (%)
TBP-AE α-DBE-DBCH β-DBE-DBCH BATE PBBz PBT PBEB TBP-DBPE HBB PBBA EH-TBB BTBPE BEH-TEBP syn-DDC-CO anti-DDC-CO OBIND DBDPE TBBPA α-HBCDD β-HBCDD γ-HBCDD BDE-28 BDE-35 BDE-47 BDE-49 BDE-66 BDE-77 BDE-85 BDE-99 BDE-100 BDE-153 BDE-154 BDE-182 BDE-183 BDE-184 BDE-191 BDE-196 BDE-197 BDE-203 BDE-206 BDE-207 BDE-208 BDE-209
− 13 9.5 0.79 − − 0.97 1.1 4.9 − 42 71 490 8.8 15 2.2 100 350 1400 1100 510 1.8 5.7 48 4.9 3.1 0.29 0.85 62 3.9 8.0 4.1 0.80 11
− 6.6 5.5 0.11 − − 0.51 0.12 0.43 − 25 42 300 2.3 8.3 0.57 70 62 94 23 43 0.50 1.7 22 1.16 0.37 0.12 0.23 27 0.16 2.5 1.8 0.19 3.6
0.46 11 6.3 27 190 55 25 1300
