High Levels of Polybrominated Diphenyl Ethers in Vacuum Cleaner

Mar 23, 2015 - Environmental Chemistry Laboratory, California Department of Toxic Substances Control, 700 Heinz Avenue, Berkeley, California 94710, Un...
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High Levels of Polybrominated Diphenyl Ethers in Vacuum Cleaner Dust from California Fire Stations Beverly Shen,*,† Todd P. Whitehead,† Sandra McNeel,‡ F. Reber Brown,§ Joginder Dhaliwal,§ Rupali Das,‡ Leslie Israel,∥ June-Soo Park,§ and Myrto Petreas§ †

School of Public Health, University of California, 50 University Hall, Berkeley, California 94720, United States Environmental Health Investigations Branch, California Department of Public Health, 850 Marina Bay Parkway, Richmond, California 94804, United States § Environmental Chemistry Laboratory, California Department of Toxic Substances Control, 700 Heinz Avenue, Berkeley, California 94710, United States ∥ Center for Occupational and Environmental Health, University of California, 5201 California Avenue, Irvine, California 92617, United States ‡

S Supporting Information *

ABSTRACT: Firefighters are exposed to chemicals during fire events and may also experience chemical exposure in their fire stations. Dust samples from used vacuum cleaner bags were collected from 20 fire stations in California and analyzed for polybrominated diphenyl ethers (PBDEs), polycyclic aromatic hydrocarbons (PAHs), and polychlorinated biphenyls (PCBs) using gas chromatography−mass spectrometry. Median dust concentrations were higher for PBDEs (e.g., 47 000 ng/g for BDE-209) than for PAHs (e.g., 220 ng/g for benzo[a]pyrene) or PCBs (e.g., 9.3 ng/g for PCB-180). BDE-209 concentrations in dust from California fire stations were among the highest of any previously documented homes or occupational settings in the world. We examined factors such as the frequency of emergency responses, the number of fire vehicles on site, and building age, but we could not account for the high levels of BDE-209 observed in fire station dust. Based on the findings of our pilot study, we hypothesize that possible sources of BDE-209 in fire stations include contaminated ash tracked back from fire events via boots, clothing, and other equipment as well as specialized equipment treated with BDE-209, including turnout gear and fire vehicles. We suggest possible followup studies to confirm these hypotheses.

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INTRODUCTION

items and building materials, and PCBs have been found in combustion gas and soot deposits from simulated house fires.17 To date, chemical exposure assessments performed on firefighters have been limited to air measurements18−20 and biomonitoring,15,19−21 to characterize the chemical hazards present during fire suppression; however, we hypothesize that firefighters may also be exposed to chemical hazards when they are away from fire events. Ash containing chemicals from fire events has been measured on the pant cuffs22 and helmets23 of firefighters, suggesting that chemical contaminants may be tracked back to fire stations from fire events. Firefighters also maintain prolonged contact with specialized equipment, such as turnout gear and fire vehicles, that may be specially treated to resist fire. On-duty firefighters live and work at their fire stations when they are not actively suppressing fires. As such, it is expected that settled dust in fire stations is an important source of firefighters’ exposure to chemicals, in the same way that settled dust in private homes is known to be an important

Firefighters experience many unique occupational hazards including ergonomic hazards,1−3 post-traumatic stress,3−6 and overexertion.1 Firefighters are also potentially exposed to a wide range of chemicals during fire suppression.7 These include polycyclic aromatic hydrocarbons (PAHs), polybrominated diphenyl ethers (PBDEs), and polychlorinated biphenyls (PCBs). PAHs are combustion products that are present at high concentrations in the air during fire events8,9 and on burnt surfaces after fire events.10 Urine biomonitoring has indicated that firefighters responding to fire events are exposed to PAHs.11−13 PBDEs are flame retardants that were widely used in California to treat furniture, electronics, and other household items as well as building materials. Ash produced after PBDEtreated materials burn in fires may contain as much as 5% PBDE by weight, as well as smaller amounts of dioxins and furans.14 Biomonitoring of serum has indicated that California firefighters are exposed to PBDEs.15,16 Likewise, urinary biomonitoring has suggested that New York City firefighters responding to the World Trade Center fires were exposed to ash contaminated with antimony, a common PBDE synergist.13 Similar to PBDEs, PCBs can be found in certain household © XXXX American Chemical Society

Received: November 7, 2014 Revised: January 29, 2015 Accepted: March 23, 2015

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Table 1. Summary of PBDE, PAH, and PCB Concentrations (ng/g)a in 27 Dust Samples from 20 Fire Stationsb in the Firefighters Occupational Exposure Study (FOX) (2010−2011), and Median Concentrations from Reference California Residencesc,d (2010)29−31 % of FOX samples above MRL

FOX min.

FOX mean

FOX max.

FOX med.

CA res. med.

PBDEs BDE-28 BDE-47 BDE-99 BDE-100 BDE-153 BDE-154 BDE-183 BDE-196 BDE-197 BDE-206 BDE-207 BDE-208 BDE-209

chemical

100 100 100 100 100 100 100 100 100 100 100 100 100

6.60 1310 2450 485 332 250 16.9 9.47 6.29 214 109 60.4 8070

113 14 600 31 000 5430 3990 2860 151 106 63.1 1860 852 488 78 200

620 94 900 201 000 36 000 232 000 18 100 644 399 255 9680 4570 2250 391 000

40.3 5170 9240 1720 1220 919 77.9 76.6 51.1 1130 592 379 47 000

20 1300 2100 330 290 150 17 8.2 7.6 75 54 33 2500

PAHs fluoranthene pyrene benzo[a]anthracene chrysene benzo[b]fluoranthene benzo[k]fluoranthene benzo[a]pyrene indeno[1,2,3-c,d]pyrene dibenzo[a,h]anthracene benzo[g,h,i]perylene

100 100 100 100 100 100 100 100 100 100

241 428 56.1 231 113 50.0 46 55.7 17.3 176

634 1330 187 625 369 167 204 214 59.0 771

1540 5610 844 2800 831 297 402 384 96.1 1690

662 1040 158 547 357 173 216 222 61.3 688

130 190 29 110 61 41 34 35 10 86

PCBs PCB-28 PCB-52 PCB-101 PCB-105 PCB-118 PCB-138 PCB-153 PCB-180

100 100 100 100 100 100 100 100

0.222 0.648 0.873 0.356 0.603 1.95 1.61 2.22

1.89 8.55 19.5 7.19 16.4 19.1 15.3 11.7

10.5 75.4 151 67.9 152 166 104 31.5

1.13 1.95 2.42 1.02 2.10 5.88 6.20 9.28

1.2 2.4 3.4 0.8 2.0 3.2 3.4 1.8

a

Med. = median, min. = minimum, max. = maximum, res. = residences, MRL = method reporting limit. bIn estimating summary statistics, multiple vacuum bags from the same fire station were treated as individual observations (7 of 20 fire stations provided 2 vacuum bags each). cSample sizes for California residences were as follows: PBDEs, N = 203; PAHs, N = 204; PCBs, N = 202. dChemical concentrations in fire station samples and California house samples were analyzed by the same laboratories using the same analytical protocols.

dust samples from 20 of these fire stations (3 in 2010 and 17 in 2011) were collected during on-site surveys. Participating fire stations were selected to represent a variety of emergency response volume and building age. Study protocols were approved by the institutional review boards of the California Department of Public Health and the University of California, Irvine. Dust Sampling. Dust samples were collected from vacuum cleaners used in the living and administrative quarters of the fire stations. All fire stations reported using commercially available residential vacuum cleaners of the same common brand (in 17 of 20 stations where brand could be identified). However, the age of the vacuum cleaner was not captured in our questionnaire. If there were two vacuum cleaners at a fire station, both vacuum cleaner bags were collected. Seven fire stations each possessed two vacuum cleaners and 13 fire stations each possessed only one vacuum cleaner, yielding a

source of human exposure to PBDEs24−26 and PCBs.27 Indoor dust acts as a reservoir for semivolatile and nonvolatile environmental contaminants, and measurements of chemicals in dust from fire stations serve as surrogates for firefighters’ chemical exposures away from fire events. In this pilot study, concentrations of PBDEs, PAHs, and PCBs were measured in dust from 20 California fire stations. Chemical concentrations in fire station dust were compared to concentrations previously reported in dust from residences and other occupational settings worldwide.

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MATERIALS AND METHODS In 2010−2011, Biomonitoring California (http:// biomonitoring.ca.gov) conducted a biomonitoring study of firefighters (Firefighters’ Occupational Exposure Study, or FOX) across several fire stations in a fire agency that serves 71 fire stations within California.16 In this companion study, B

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concentrations in multiple bags collected from the same fire station when evaluating potential explanatory factors. Significant associations were determined at α ≤ 0.05.

total of 27 vacuum cleaner bags collected. After removal, the vacuum cleaner bags were sealed in a polyurethane bag and shipped to the Environmental Chemistry Laboratory at the California Department of Toxic Substances Control (DTSC) in Berkeley, California, where they were stored at 4 °C until analysis. Surveys. During dust collection, a two part on-site survey was conducted. An observational survey was completed by an industrial hygienist during a walk-through and a vacuum cleaner use questionnaire was administered to an available fire station staff member. The walk-through survey recorded housekeeping procedures, turnout gear storage, and general cleanliness. The vacuum cleaner questionnaire ascertained the locations of vacuum cleaner use and the frequency of bag change-out. Prior to dust collection, the fire agency provided the most recent information on each fire station’s total number of fire incident responses and total number of hazardous material incidents (from 2008 and 2009). Reported fire incident data included only commercial property and vehicle fires; data on residential fire incidents was unavailable at that time. Information on the number of fire vehicles maintained and fire station age was also provided. Chemical Analysis. Dust samples were sieved to remove fibers and debris larger than 150 μm. The resulting fine dust was weighed into approximately 0.2 g portions, spiked with a mixture of labeled internal standards (see Supporting Information (SI), S1) and extracted by accelerated solvent extraction (Dionex, Sunnyvale, CA). The extracts were cleaned using silica gel column chromatography and gel permeation chromatography (Waters Corp, Milford, MA). The cleaned extracts were solvent-exchanged into tetradecane and spiked with a mixture of labeled injection standards (see SI, Table S1). Each run contained a method blank, a duplicate, and a reference material. For the latter, we used the National Institute of Standards and Technology Standard Reference Material (NIST SRM) No. 2585 in each run to verify the accuracy and precision of the analytical method (see SI Table S2). Extracts were analyzed for 22 PBDEs and 15 PCBs using highresolution gas chromatography−mass spectrometry operated with electron impact ionization mode (GC-HRMS/EI; ThermoFinngan DFS and MAT95, Bremen, Germany) at DTSC (see SI Table S1 for complete analyte list). For PBDE analysis, the extracts were diluted 1:5 before analysis. Extracts were analyzed for 11 PAHs using conventional GC-MS/EI (Agilent Technologies 6890−5973, Santa Clara, CA) at the University of California, Berkeley (UCB). Method reporting limits (MRLs) were calculated based on the mass of each chemical measured in method blanks. For each chemical, MRLs were set at five times the standard deviation of chemical masses in 57 method blanks analyzed using the protocol described above. Statistical Methods. Summary statistics were generated using Microsoft Excel (Microsoft Office 2011 for Mac OS X). Statistical analyses were conducted using Stata 10 (StataCorp. 2007. Stata Statistical Sof tware: Release 10. College Station, TX: StataCorp LP). Spearman’s rank correlation coefficient was used to assess the bivariate relationships between concentrations of each chemical and each explanatory factor reported in the surveys (i.e., number of fire incidents, number of hazardous material incidents, number of fire vehicles, and fire station age). A mixed-effects model was also used to examine the variability in chemical concentrations within and between stations and to account for the correlation between chemical

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RESULTS Characteristics of Fire Stations. The fire stations consisted of some combination of a living/entertainment quarter, a sleeping quarter, an administrative center, and a vehicle bay. The fire station building types consisted of 90% permanent buildings and 10% temporary trailers that were in use during fire station construction. The number of firefighters per shift ranged from 3 to 12. SI Table S3 shows descriptive data for the fire stations. The construction dates of the fire stations ranged from 1940 to 2009. The number and types of vehicles present at the fire stations varied, with 100% of fire stations having fire engines, 18% having rescue trucks, and 0% having hazardous material trucks. Chemicals in Fire Station Dust. Table 1 displays summary statistics for concentrations of selected PBDEs, PAHs, and PCBs measured in dust from 27 vacuum cleaner bags. In general, concentrations of PBDEs were higher than concentrations of PAHs and concentrations of PAHs were higher than concentrations of PCBs in the fire stations. Each of three major PBDE congeners had median dust concentrations above 5000 ng/g (5170 ng/g for BDE-47; 9240 ng/g for BDE99; and 47 000 ng/g for BDE-209). As shown in Figure 1,

Figure 1. Comparison of major PBDE congener contribution from each sample. The following samples were collected from the same station: 3 and 4, 9 and 10, 11 and 12, 13 and 14, 15 and 16, 22 and 23, 24 and 27.

BDE-209 was the predominant PBDE congener measured in the dust from these fire stations. For 23 dust samples, BDE-209 was the congener found at the highest concentration. For 20 dust samples, BDE-209 represented at least 50% of ∑22PBDEs. Four PAHs had median dust concentrations above 500 ng/g (662 ng/g for fluoranthene; 1040 ng/g for pyrene; 547 ng/g for chrysene; and 688 ng/g for benzo[g,h,i]perylene). Pyrene was the predominant PAH measured in these dust samples, with higher mean, median, minimum, and maximum values than other measured PAHs. Three PCB congeners had median dust concentrations above 5 ng/g (5.88 ng/g for PCB-138; 6.20 ng/g for PCB-153; and 9.28 ng/g for PCB-180). PCB-180 was the predominant PCB congener, with higher mean, median, minimum, and maximum values than other PCB congeners. C

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Table 2. Spearman’s Rank Correlation Coefficients between Select Chemicals in Fire Stations and Explanatory Factors no. no. no. fire a

of fire incidents of hazardous material incidents of vehicles station age

BDE-47

BDE-99

BDE-209

benzo[a]pyrene

benzo[g,h,i]perylene

PCB-138

PCB-153

PCB-180

0.05 0.19 0.08 0.60a

0.11 0.25 0.09 0.59a

−0.34 −0.27 −0.03 −0.13

0.69a 0.74a 0.30 0.05

0.67a 0.78a 0.16 0.01

0.13 0.23 0.11 0.67a

0.10 0.20 0.07 0.66a

−0.10 −0.03 −0.08 0.33

Statistically significant Spearman rank correlation (p < 0.05) between chemical concentrations in dust and explanatory factor.

fire stations. Brown et al. measured non-PBDE brominated flame retardants in the same cohort of fire stations,28 whereas in this complementary pilot study, we assessed the concentration of PBDEs, PAHs, and PCBs in the fire station dust and tried to identify the determinants of the observed concentrations. Median concentrations of PBDEs and PAHs in the fire station dust samples were substantially higher than levels previously estimated for dust from California homes using the same laboratories and the same analytical protocols.29,30 In contrast, median dust concentrations of PCBs 28, 52, and 101 in the fire stations were similar to those found in California residences.31 In these 20 fire stations, the concentration of PBDEs in dust far exceeded the concentrations of PAHs and PCBs. In particular, the levels of BDE-209 in the fire station dust samples (maximum of 390 μg/g) are among the highest ever reported (see Figure 2).32 Assuming one has a body mass

Individual PBDEs were highly correlated within groups corresponding to the composition of commercial mixtures, with Spearman correlation coefficients ranging from 0.80−0.99 among the lower brominated PBDEs and from 0.60−0.96 among the higher brominated PBDEs. Likewise, chemical concentrations were correlated within the group of PAHs (r range: 0.52−0.94) and PCBs (r range: 0.65−0.99, excluding PCB-180). PCBs were also correlated with the lower brominated PBDEs with correlation coefficients ranging from 0.52−0.80. BDE-209 was negatively correlated with specific PAHs, including benzo[a]pyrene, indeno[1,2,3-c,d]pyrene, dibenzo[a,h]anthracene, benzo[g,h,i]perylene (r range: −0.42 to −0.50), whereas specific lower brominated PBDEs were positively correlated with specific PAHs (e.g., BDE-99 and fluoranthene, indeno[1,2,3-c,d]pyrene, dibenzo[a,h]anthracene; r range: 0.38−0.40) (see SI Table S4 for complete results of correlation between analytes). For each of the 7 fire stations that provided two vacuum cleaner bags, SI Figures S1 and S2 illustrate the within-fire station variability in PBDE concentrations and PAH concentrations, respectively. SI Table S5 shows estimated withinstation variance (σ2w), between-station variance (σ2b), and the intraclass correlation coefficient [ρ= σ2b/(σ2b+ σ2w)] for each chemical. Within-station variance accounted for 9−39% of total variance in levels of BDE-47, BDE-99, and BDE-209 (ρ range: 0.61−0.91). In benzo[a]pyrene (ρ = 0.44) and benzo[g,h,i]perylene (ρ = 0.79), within-station variance accounted for 56% and 21% of total variance, respectively. Within-station variance accounted for between 11% and 78% of total variance in levels of PCB-138, PCB-153, and PCB-180 (ρ range: 0.22−0.89). Determinants of Chemical Levels. Table 2 describes the relationship between chemical concentrations and possible explanatory factors for the predominant congeners from each chemical class. Fire station age was positively correlated with concentrations of BDE-47, BDE-99, PCB-138, and PCB-153. Concentrations of benzo[a]pyrene and benzo[g,h,i]perylene were positively correlated with fire and hazardous material incident frequency. There were no significant relationships between BDE-209 concentrations and any of the explanatory factors evaluated. We also applied a mixed-effects model to account for the correlation between two samples collected from the same fire station and similarly, observed significant positive associations between fire station age and concentrations of BDE-47, BDE-99, PCB-138, PCB-153 as well as significant positive associations between incident frequency and concentrations of benzo[a]pyrene, benzo[g,h,i]perylene (see SI Table S5). There were no significant relationships between BDE-209 concentrations and any of the environmental factors evaluated in the mixed-effects model.

Figure 2. Comparison of median BDE-209 levels between California fire stations, other occupational settings,35−39 North American residences,24,29,48,49 and United Kingdom residences35

of 70 kg and ingests 50 mg of dust a day,33 a concentration of 390 μg/g of BDE-209 in dust corresponds to a dose of 280 ng/ kg-day. Elevated PBDE levels have been reported in dust collected from California homes in the past, most likely due to the state’s unique flammability standards.34 However, the median BDE-209 concentration in the fire stations exceeded the median BDE-209 concentration from a reference population of California residences29 (measured by the same laboratories using the same analytical protocols) by nearly 20fold (47 000 ng/g and 2500 ng/g, respectively). Moreover, median BDE-209 levels in fire station dust (47 000 ng/g) were higher than median BDE-209 levels in previously reported occupational settings (e-waste: 20 000 ng/g; planes: 17 000 ng/ g).35−39 None of the explanatory factors we considered could account for the high levels of BDE-209 observed in fire station dust.

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DISCUSSION Although many studies have characterized risks faced by firefighters, few have assessed their exposures to chemicals and only FOX has measured chemical concentrations in dust from D

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and 56% of total variance in BDE-209 and benzo[a]pyrene levels, respectively), but we were unable to determine the reason for the differences. Each matched vacuum bag originated from a unique wing within its fire station, so the observed variability in PBDE and PAH levels between two bags taken from the same fire station suggest that between-room differences in PBDE and PAH levels exist; however, we were not able to identify specific rooms within each wing that were consistently associated with higher PBDE and PAH levels throughout all the fire stations. Limitations. As an indicator of firefighters’ chemical exposures away from fire events, we characterized chemical levels in dust collected from vacuum cleaners that were used for day-to-day cleaning at each participating fire station. The primary advantages of this sampling method are convenience and cost efficiency. The primary limitation of this sampling method is that from one fire station to the next, vacuum cleaners may be used in a different combination of rooms and at different proximity to chemical sources. Differences in vacuum cleaning practices between fire stations as well as differences in the vacuum cleaners used to collect dust (e.g., type, efficiency) could introduce variability in chemical levels. Moreover, we could not rule out if components of the vacuum cleaners contained PBDEs, possibly resulting in an overestimation of PBDE levels in fire station dust. However, all fire stations were found to use commercially available residential vacuum cleaners of a brand commonly used in private California homes,29 the comparison population used in this analysis. Despite these limitations, because indoor dust acts as a reservoir for semivolatile and nonvolatile environmental contaminants, vacuum-bag dust is a useful marker of indoor chemical contamination. This study was limited in that it was not designed to identify the determinants of chemical contaminants. The on-site surveys only generally inquired after the cleanliness and maintenance of each fire station. Future studies should include a more detailed and rigorous assessment to further explore and identify the source(s) of the high levels of PBDEs observed in this study. For example, in the biomonitoring study of the California firefighters, lower serum levels of PBDEs were found in firefighters who practiced more hygienic turnout gear storage.16 In the current analysis, we were unable to assess the impact of turnout gear storage practices on vacuum-dust PBDE levels, as the small number of firefighters surveyed in the participating fire stations was not sufficient to represent station-wide practices. Our ability to identify statistical relationships between explanatory factors and chemical levels in fire station dust was also limited by our small sample size (N = 20 stations, 27 samples). It is also notable that available data on fire incidents were limited to commercial property, vehicle, and hazardous material incidents, and did not include residential fire incidents. These missing data reduced the precision of the estimates of total fire incidents and the resulting measurement error may have limited our ability to detect relationships between the frequency of emergency responses and chemical levels. Additionally, we do not know if the materials in turnout gear worn by firefighters contain any PBDEs. A future study could screen turnout gear for bromine using X-ray fluorescence (XRF) and, if positive, confirm the type of flame retardant used by chemical analysis of the material. We did not assess directly whether chemical contaminants were being tracked back from fire events to the fire stations. To assess whether track-back from fires is causing the observed

PAHs are combustion products that are present at high concentrations in the air during fire events8,9 and on burnt surfaces after fire events, 10 to which firefighters are exposed.11−13 Investigators have found PAHs on firefighter gear,40 suggesting that firefighters can carry dust contaminated with combustion products into their fire stations following fire incident responses. Likewise, based on our observations of (1) elevated levels of PAHs in fire station dust and (2) positive relationships between PAH levels and the number of fire and hazardous material incidents, we suggest that firefighters are exposed to PAH-contaminated ash at fire events and subsequently transport PAHs back to the fire station via boots, clothing, and other equipment. This type of chemical track-back has often been observed with pesticides in agricultural communities.41−43 As PBDE combustion products, PBDDs and PBDFs, have been measured and found in air and ash after fire events14,22 and on firefighters’ pants,22 firefighters may also carry dust contaminated with PBDEs into their fire stations following fire incident responses. Park et al. observed that firefighters who reported cleaning their turnout gear after fire events had lower serum PBDE levels than firefighters who stored their gear without cleaning,16 an observation which supports the hypothesized role of PBDE-contaminated dust from fire events as a source of firefighter exposure. However, concentrations of BDE-209 were negatively correlated with concentrations of PAHs in the fire stations, suggesting that these chemicals may have distinct sources. Moreover, the lack of a positive association between BDE-209 and the number of fire incidents limits the likelihood that ash tracked back from fires was the only source of elevated BDE-209 levels. Further studies will be required to confirm or eliminate the possibility of PBDE trackback in fire stations. An alternative source for the high levels of BDE-209 observed in fire station dust may be the specialized equipment used in firefighting, including turnout gear and vehicles. A previous study showed that some turnout gear does contain the flame retardant synergist, antimony; and that elevated urinary antimony levels in firefighters were partially attributable to contact with firefighting gear.44 Similarly, if the turnout gear of these California firefighters has been treated with PBDEs, this could explain the high levels of PBDEs observed in the dust from their fire stations and possibly their high serum levels.16 Moreover, it is possible that fire vehicle interiors are treated with higher concentrations of flame retardants, as even standard vehicle interiors have been shown to be a significant source of exposure to BDE-209.45−47 It is possible that PBDEcontaminated dust could be transferred from fire vehicle bays to fire station living quarters. However, we did not observe a positive relationship between BDE-209 concentrations and the number of fire vehicles. As we did not have any detailed information on the fire equipment used in each station (e.g., make/model/year of fire vehicles, type of turnout gear), we were unable to draw definitive conclusions on the possibility of such equipment being a source of PBDEs. Observed positive relationships between PCB levels and fire station age are consistent with similar observations in California homes31 and suggest that the PCB-contaminated materials may still be present in fire stations built before the 1970s, when PCBs were banned. There were differences in PBDE and PAH levels from dust samples taken from two separate vacuum cleaners used in the same fire station (within-station variance accounted for 39% E

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ASSOCIATED CONTENT

S Supporting Information *

Additional information as noted in the text. This material is available free of charge via the Internet at http://pubs.acs.org.

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AUTHOR INFORMATION

Corresponding Author

*E-mail: [email protected]. Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS We thank all the firefighters and staff of the California fire stations who participated in this study and facilitated access to the fire stations. We also thank Kate Durand for assisting with the on-site surveys and Joe Fedoruk for assisting with sample collection. This work was supported in part by the National Institute of Environmental Health Sciences (NIEHS, grant number P01ES018172) and by the California Department of Public Health. Its contents do not necessarily represent the official views of Impact Assessment, Inc., the California Department of Public Health, or the California Department of Toxic Substances Control.

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DOI: 10.1021/es505463g Environ. Sci. Technol. XXXX, XXX, XXX−XXX