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Flame Retardant Transfers from U.S. Households (Dust and Laundry
Wastewater) to the Aquatic Environment
Erika D. Schreder*
,†
and Mark J. La Guardia
‡
†
Washington Toxics Coalition, 4649 Sunnyside Avenue N, Suite 540, Seattle, Washington 98103, United States
‡
Department of Environmental & Aquatic Animal Health, Virginia Institute of Marine Science, College of William & Mary,
Gloucester Point, Virginia 23062, United States
*
SSupporting Information
ABSTRACT: Levels of flame retardants in house dust and a
transport pathway from homes to the outdoor environment
were investigated in communities near the Columbia River in
Washington state (WA). Residential house dust and laundry
wastewater were collected from 20 homes in Vancouver and
Longview, WA and analyzed for a suite of flame retardants to
test the hypothesis that dust collecting on clothing and
transferring to laundry water is a source of flame retardants to
wastewater treatment plants (WWTPs) and subsequently to
waterways. Influent and effluent from two WWTPs servicing
these communities were also analyzed for flame retardants. A
total of 21 compounds were detected in house dust, including
polybrominated diphenyl ethers (PBDEs), 2-ethylhexyl-2,3,4,5-
tetrabromobenzoate (TBB or EH-TBB), bis(2-ethylhexyl) 3,4,5,6-tetrabromophthalate (TBPH), 1,2-bis(2,4,6,-
tribromophenoxy)ethane (BTBPE) and decabromodiphenylethane (DBDPE), hexabromocyclododecane (HBCD or
HBCDD), tetrabromobisphenol A (TBBPA), and three chlorinated organophosphate flame retardants (ClOPFRs), tris(1,3-
dichloro-2-propyl)phosphate (TDCPP or TDCIPP), tris(1-chloro-2-propyl)phosphate (TCPP or TCIPP), and tris(2-
chloroethyl)phosphate (TCEP). Levels ranged from 3.6 to 82,700 ng g−1(dry weight). Of the 21 compounds detected in
dust, 18 were also detected in laundry wastewater. Levels ranged from 47.1 to 561,000 ng L−1. ClOPFRs were present at the
highest concentrations in both dust and laundry wastewater, making up 72% of total flame retardant mass in dust and 92% in
laundry wastewater. Comparison of flame retardant levels in WWTP influents to estimates based on laundry wastewater levels
indicated that laundry wastewater may be the primary source to these WWTPs. Mass loadings to the Columbia River from each
treatment plant were by far the highest for the ClOPFRs and ranged up to 114 kg/yr for TCPP.
■INTRODUCTION
The global use of flame retardants (FRs) in consumer and
building products, including in polyurethane foam items such as
couch cushions, in plastics such as television housings, in
electronics, and in building materials including insulation, has
led to their accumulation throughout the environment.
1−3
With
the exception of known discharges from manufacturing,
recycling, and wastewater treatment, the mechanisms by
which FRs are transported from indoor to outdoor environ-
ments are poorly understood.
4,5
FRs have been detected in air,
water, sediments, surface films, and tree bark, indicating that
once released from associated materials, they can enter the
environment through multiple pathways.
6−9
A recent report
detected a broad suite of 62 FRs in indoor dust, and several
reports have detected many of these compounds on surface
wipes, hands, hair, and in clothes dryer lint, indicating their
mobility within the indoor environment.
2,10−12
Incidental
ingestion of dust is believed to be a significant pathway for
human exposure to FRs. In addition to detections in humans,
including in breast milk, adipose tissue, and serum, a number of
FRs have been detected in shell- and finfish and marine
mammals including orcas, indicating their potential to
accumulate in the aquatic environment.
13,14
Some FRs have
been linked to toxic effects including cancer, hormone
disruption, neurotoxicity, and reproductive impacts.
3,15
Because of their heavy use in polyurethane foam as well as in
household plastics, polybrominated diphenyl ethers (PBDEs)
were the dominant FR analyzed in U.S. household dust until
recently.
1,16
Industry ended U.S. production of the penta
formulation of PBDEs at the end of 2004 and sales of the deca-
BDE formulation at the end of 2013.
17,18
Recent tests of foam-
containing products and of dust in U.S. homes indicate
increased use of chlorinated organophosphate flame retardants
(ClOPFRs) such as tris(1,3-dichloro-2-propyl)phosphate
(TDCPP) and tris(1-chloro-2-propyl)phosphate (TCPP), as
Received: May 14, 2014
Revised: July 11, 2014
Accepted: July 18, 2014
Article
pubs.acs.org/est
© XXXX American Chemical Society Adx.doi.org/10.1021/es502227h |Environ. Sci. Technol. XXXX, XXX, XXX−XXX
well as components of the FR Firemaster 550 (Chemtura, PA,
USA): triphenyl phosphate (TPP), bis(2-ethylhexyl) 3,4,5,6-
tetrabromophthalate (TBPH), and 2-ethylhexyl-2,3,4,5-tetra-
bromobenzoate (TBB).
2,19
Other FRs known to be found
extensively in consumer and building products include
tetrabromobisphenol A (TBBPA), used in electronics, and
hexabromocyclododecane (HBCD), used primarily in insu-
lation and to a lesser extent on textiles.
20,21
Due to growing
environmental and human health concerns, the U.S. Environ-
mental Protection Agency (USEPA) is now evaluating these
and 13 other FRs under the Toxic Substances Control Act.
22
PBDEs were phased out largely because of their ability to
persist in the environment and build up in the food chain along
with evidence of toxicity.
23
In the Columbia River, USA and
Canada, PBDEs have been detected in the bodies and stomach
contents of juvenile salmon, with the highest concentrations in
more industrialized areas of the lower Columbia.
24
Some FRs
such as HBCD share PBDEs’characteristic as persistent
bioaccumulative compounds.
3
These hydrophobic compounds
partition preferentially to sewage sludge, with more than 90% of
PBDEs in wastewater treatment found in sludge.
25,26
Others,
such as ClOPFRs, are more hydrophilic and pass through
WWTPs, partitioning to effluent rather than sludge.
15
A U.S.
Geological Survey study found two ClOPFRs (TCEP and
TDCPP) in effluent from each of nine WWTPs discharging
into the Columbia River at levels ranging from 120 to 690 ng
L−1.
27
No data have been published on levels of ClOPFRs in
Columbia River surface water. However, Kolpin et al. found
TCEP in 58% of 85 U.S. streams sampled in 1999 and 2000, at
a median level of 100 ng L−1.
28
European studies have also
investigated ClOPFRs in surface water: TCEP, TDCPP, and
TCPP were detected in urban and rural surface waters in
Germany.
29,30
ClOPFRs have been detected in biota including
mollusks, fish, birds, and bird eggs.
15,31
This study tested the hypothesis that clothing, and the dust it
carries, creates a pathway for chemicals used in household
products to travel to waterways. In this pathway, chemicals such
as FRs escape from household products and accumulate in
house dust and on clothing. When that clothing is washed, the
FRs and/or particulate matter including FRs enter laundry
wastewater and make their way to wastewater treatment
facilities. Depending on the chemical, a certain percentage of
the load survives treatment and is then discharged to a
waterway. This study focused on homes associated with
treatment plants in Washington state (WA), USA, that
discharge to the lower Columbia River.
■EXPERIMENTAL SECTION
A convenience sample of 20 households in Longview and
Vancouver, WA was recruited via newsletters, electronic mailing
lists, local businesses, and organizations. Researchers visited
homes to collect dust and laundry wastewater in 2011 and
2012. The homes sampled were all single family homes, 90% in
suburban and 10% in rural areas.
Dust was collected using a Eureka Mighty-Mite (model
3670G) vacuum fitted with a cellulose filter (Whatman 2800-
199) held in the crevice tool with a stainless steel ring.
16
Researchers collected dust from primary living areas including
kitchen, living room, bedroom, office, and dining room by
moving the crevice tool slowly across bare floor and carpet. A
sample of sodium sulfate was collected in the same manner
from a clean surface in place of a field blank; no FRs were
detected (>1 ng g−1) in this sample.
11
Participants prepared a full load of laundry to primarily
include clothing worn around the house, with type and number
of items tracked (i.e., pajamas, jeans; none appeared to be
specialty FR-treated work clothes). The home washing machine
was used to wash the clothing using Natural 2X Concentrated
Liquid Laundry Detergent (Seventh Generation, Burlington,
VT, USA) and warm water (detergent was separately analyzed
for FRs and none were detected). Samples (1 L) of the laundry
wastewater were collected in amber glass bottles at the end of
the agitation cycle, placed on dry ice in the field, and stored at
<4 °C until analyzed. Blank water samples were collected prior
to addition of clothing and detergent.
A single grab sample (1 L) of influent and effluent was
collected in amber glass bottles from the Three Rivers Regional
Wastewater Treatment Plant in Longview, WA, and the Marine
Park Wastewater Treatment Plant in Vancouver, WA.
Collection of influent and effluent was timed so effluent was
collected after the estimated residence time, collecting a “plug”
before and after treatment. Samples were stored on dry ice until
placement in a freezer (<4 °C).
Analysis of the Brominated FRs (BFRs). PBDEs (BDE-
28, -47, -66, -85, -99, -100, -153, -154, -183, -206, -209),
alternative-BFRs (alt-BFRs: BTBPE, DBDPE, TBB and
TBPH), and HBCD isomers (α-, β-, γ-HBCD) by ultra-
performance liquid chromatography (UPLC)-atmospheric
pressure photoionization (APPI) tandem mass spectrometry
(MS/MS) described by La Guardia et al.
32
was modified for
this study to include TBBPA and the ClOPFRs (TCEP, TCPP,
and TDCPP).
32
(Targeted analyte names, acronyms, and
chemical formulas are listed in Supporting Information, Table
S1, along with methodology and instrument setting.) Briefly,
∼1 g (dry weight) sieved (300 μm) dust sample was subjected
to accelerated solvent extraction (ASE 200, Dionex, Sunnyvale,
CA, USA) with dichloromethane (DCM). Surrogate standards
(200 ng of 2,3,4,4',5,6-hexabromodiphenyl ether (BDE-166);
Cambridge Isotope Laboratories, Inc., Andover, MA, USA and
1000 ng of deuterated triphenyl phosphate (d15-TPP); Sigma-
Aldrich, St. Louis, MO, USA) were added to each sample prior
to extraction. Extracts were purified by size exclusion
chromatography (SEC, Envirosep-ABC, 350 mm ×21.1 mm.
column; Phenomenex, Torrance, CA, USA). Each post-SEC
extract was solvent exchanged to hexane, reduced in volume,
and added to the top of a solid phase extraction (SPE) glass
column containing 2 g of silica (Isolute, International Sorbent
Tech.; Hengoed Mid Glamorgan, U.K.). Each column was
eluted with 3.5 mL hexane (fraction one), followed by 6.5 mL
of 60:40 hexane/DCM, 8 mL DCM (fraction two), and 5 mL
50:50 acetone/DCM (fraction three). The second fraction,
containing PBDEs, alt-BFRs, and HBCD, and the third fraction,
containing ClOPFRs and TBBPA, were reduced and solvent
exchanged to methanol, and the internal standard decachlor-
odiphenyl ether (DCDE, 400 ng; Ultra Scientific, North
Kingston, RI, USA) was added to both fractions prior to
UPLC-APPI-MS/MS analysis.
FR Liquid Determination (Laundry Wastewater,
WWTP Influent and Effluent). Each sample (∼1 L) was
liquid/liquid extracted three times with DCM, 200 mL total.
Surrogate standards (200 ng BDE-166 and 1000 ng d15-TPP)
were added prior to extraction. The three extracts were
combined, solvent exchanged to hexane, and reduced in volume
(<1 mL). Post-extracts were purified by SPE, as noted for the
dust samples. Internal standard (DCDE, 400 ng) was added to
Environmental Science & Technology Article
dx.doi.org/10.1021/es502227h |Environ. Sci. Technol. XXXX, XXX, XXX−XXXB
each SPE fraction (two and three), and these were analyzed for
BFRs and ClOPFRs by UPLC- APPI-MS/MS.
Analytes in purified extracts were chromatographically
separated by UPLC (Acquity UPLC, Waters Corporation,
Milford, MA, USA) operated in gradient mode (100%
methanol (A1) and 100% water (B1)), equipped with a C18
UPLC analytical column (Acquity UPLC BEH C18, 1.7 μm,
2.1 mm ×150 mm, Waters Corp.). Analytes were ionized by
APPI; dopant (acetone) was introduced (150 μL/min) by a
liquid chromatography pump (LC-20AD, Shimadzu Corpo-
ration, Kyoto, Japan). Product and transition ions were
detected by triple quadrupole mass spectrometer (3200
QTrap, AB Sciex, Framingham, MA, USA) operated in the
multiple reaction monitoring (MRM) mode. Quantitation ions
for BFRs (mass to charge ratio, m/z) were m/z79 ([79Br]−)
and 81([81Br]−), and m/z 35 ([35Cl]−), 37([37Cl]−) for
ClOPFRs and DCDE. Positive ions m/z342 and 343 were
monitored for d15-TPP quantitation. (Additional sample
preparation and UPLC-APPI-MS/MS operating conditions
can be found in Supporting Information).
Method validation was established by performance-based
QA/QC including method blanks, surrogate, duplicate, and
matrix spike analysis. (Surrogate recoveries are listed with the
sample results in Supplementary Tables S3, S5, S7, and S8).A
National Institute of Standards and Technology (NIST)
Standard Reference Material (SRM) #2585 (house dust) was
also analyzed; SRM #2585 mean % recoveries for ∑PBDEs,
∑alt-BFRs, ∑HBCDs, ∑ClOPFRs, and TBBPA range 50−
91%; individual recoveries range 38−143%, Supplementary
Table S10). In laboratory blanks, FRs were not observed above
detection limits (>1 ng g−1) in the first batch (samples 01 to
09). However, trace amounts of TBB (4.2 ng g−1), TBPH (7.7
ng g−1), and TDCPP (16 ng g−1) were detected in the blank of
the second batch. These amounts were subtracted from results
10−20 for TBB and TBPH, as they were >10% of the lowest
detections (Quality assurance procedures including duplicate
and matrix spike results can be found in Supporting
Information, results in Supplementary Table S9).
■RESULTS AND DISCUSSION
Household Dust and Laundry Wastewater. Levels of
FRs in household dust were obtained for 20 homes. A total of
21 FRs were detected; 16 were detected in 95% or more of the
homes. Laundry wastewater was also obtained from 19 of these
homes (one sample was lost during storage), and of the 21
compounds detected in dust, 18 were also detected in laundry
wastewater. Whereas the FR contribution to dust was
dominated by the three ClOPFRs, which contributed 72% of
the total (followed by ∑PBDEs 19%, TBBPA 3.7%, ∑alt-BFRs
2.9%, and ∑HBCDs 2.5%), ClOPFRs were even more
dominant in laundry wastewater, at 92% of the total (followed
by BDE-47 at 2.5% and BDE-99 at 2.0%). This shift can be
attributed to these compounds’hydrophilic nature together
with higher solubility and lower partitioning coefficients
compared to other targeted FRs (see Supplementary Table
S1 for log Kow values). Each of the three ClOPFRs, two PBDE
congeners (BDE-47 and -209), TBB, and TBPH were detected
in 100% of laundry wastewater samples; other compounds
detected included seven additional PBDE congeners, BTBPE,
DBDPE, and HBCDs. TBBPA was not detected (>1 ng L−1)in
laundry wastewater samples. Dust results are presented in
Figure 1, and composition of PBDEs and ClOPFRs in dust and
laundry wastewater is presented in Figure 2.
Laundry wastewater field blanks were collected from 14 of
the 20 homes. Of the 22 analytes, TCEP (sample 8), TCPP
(samples 3, 8, and 18), and BDE-209 were detected in blanks,
but only BDE-209 was detected at levels >10% of the
corresponding laundry wastewater sample, in three blanks at
18%, 12%, and 21%. These values were subtracted from the
laundry wastewater analysis values for samples 8, 9, and 10. No
Figure 1. (a−d) Household dust flame retardant median concentrations (ng g−1, dry weight) and comparison results from previous studies. (Sample
collection dates).
Environmental Science & Technology Article
dx.doi.org/10.1021/es502227h |Environ. Sci. Technol. XXXX, XXX, XXX−XXXC
analytes were detected in the surrogate field blank. Individual
dust and corresponding laundry wastewater results by home
and analyte are listed in the Supporting Information,
Supplementary Tables S3−6.
Chlorinated Organophosphate Flame Retardants
(ClOPFRs). TCPP and TDCPP were detected in all dust
samples, and TCEP was detected in 95% of homes (ClOPFRs
dust results were obtained for 19 of the 20 homes due to
analytical issues). According to USEPA’s 2012 Chemical Data
Reporting (CDR), 4,500−22,700 tons/year of TDCPP were
manufactured or imported into the U.S. in 2010 and 2011;
TCPP was reported at 25,000 tons/year. According to the
CDR, TDCPP production has changed little since 1998; TCPP
volumes appear to have risen since 2006.
15,33
However, ICL
IndustrialProducts,amajorU.S.producerofTDCPP,
announced in 2012 that it would cease production of
TDCPP in 2015.
34
TCEP production fell between 2006 and
2012, but TCEP was also found at a level of 14% in the FR
Antiblaze V6 (2,2-bis(chloromethyl)propane-1,3-diyl tetrakis-
(2-chloroethyl)bis(phosphate) (Albemarle, Baton Rouge,
LA).
35
This product is primarily in automobile foam, with
production dating back to 1990 but levels not reported to CDR
for 2006 or 2012.
35
Of the 22 targeted FRs, TCPP was present in dust at the
highest level of any single chemical with a median level of 4,820
ng g−1and a maximum of 82,700 ng g−1. The primary use of
TCPP in homes is likely in polyurethane and polyisocyanate
insulation, and it has been found in the foam of some children’s
products such as car seats and changing pads.
36−39
TDCPP, in
dust samples at a median level of 1,620 ng g−1, has recently
been widely found in furniture foam as well as in children’s
products, although its use in children’s sleepwear was
withdrawn in 1977 due to its mutagenicity.
1,40,41
The median
dust level of TCEP (1,380 ng g−1) was similar to that of
TDCPP. Median levels of TDCPP and TCEP were about half
of those reported in a 2011 California dust study by Dodson et
al., while TCPP levels were about twice as high as in the
California samples (Figure 1a).
2
Dodson et al. sampled the
same homes in 2006 (median levels 2,800, 5,100 and 2,100 ng
g−1for TDCPP, TCEP and TCPP, respectively), suggesting a
decline for TDCPP and TCEP but a rise in TCPP exposure
(Figure 1a).
ClOPFRs were the FRs found at the highest levels in laundry
wastewater, and all three were detected in laundry wastewater
from every home. As with household dust, TCPP was found at
the highest levels, with a maximum of 561,000 ng L−1and a
median value of 43,500 ng L−1, followed by TDCPP with a
maximum of 65,600 ng L−1and a median value of 13,500 ng
L−1, and TCEP, with a maximum of 42,800 ng L−1and median
value of 7,680 ng L−1. The contribution of the individual
ClOPFRs to mean ∑ClOPFRs was similar in dust and laundry
wastewater, with TCPP contributing 73% and 77%, respec-
tively, followed by TCEP (14% and 9%) and TDCPP (13% and
14%) (Figure 2). The similarity in profiles in dust and laundry
wastewater may indicate that once released to the indoor
environment, these ClOPFRs have equal ability to collect on
clothing via dust and/or air. Clothing may then be acting as a
quasi-passive sampler, as previously suggested in several FR
studies of clothes dryer lint, transferring FRs, particularly those
that are more hydrophilic or water-soluble, to wastewater when
washed.
10,11,42
TCPP was also the most abundant ClOPFR
observed in several indoor passive air sampler studies.
43
Polybrominated Diphenyl Ethers (PBDEs). After the
ClOPFRs, PBDEs were the next highest in dust samples (n=
20): ∑PBDEs ranged from 311 to 19,700 ng g−1. BDE 209 was
the dominant congener in most samples. Total PBDE levels
were similar to those in 50 Boston homes sampled between
2002 and 2008 and those observed by Dodson et al. in 2011.
2,44
The median level of the penta-BDE formulation, which
includes congeners with 4−6 bromines, was about one-third
that of the 2006 samples tested by Dodson et al. (Figure 1b). A
larger study of 292 California dust samples collected between
2001 and 2007 and then again in 2010, however, reported little
change in concentration (Figure 1b).
45
The median level of BDE-209 (1140 ng g−1), the major
PBDE in the deca formulation, was consistent with the 2006
and 2011 Dodson et al. report (1,400 and 1,200 ng g−1,
respectively) and about half of levels reported in the larger
California study, 2,300 and 2,500 ng g−1for 2001−07 and 2010,
respectively (Figure 1b).
2,45
Two PBDE congeners, BDE-47 and BDE-209, were detected
in laundry wastewater from every home, with median levels of
1,230 ng L−1for BDE-47 and 140 ng L−1for BDE-209.
∑PBDEs were detected in laundry wastewater at a median
level of 2,550 ng L−1. Unlike the ClOPFR profiles, the PBDE
dust and laundry wastewater profiles were disproportional. The
dust profile favored the higher brominated, lipophilic PBDE
congener BDE-209, used primarily in television and electronics
casings, making up 50% of the mean ∑PBDEs (Figure 2). The
laundry wastewater profile, however, favored the lower
brominated, less lipophilic congeners of the penta formulation,
particularly BDE-47 and -99, which contributed 46% and 36%
of the mean, respectively. The penta formulation was used
primarily in polyurethane foam, which can degrade and
produce low-density fragments.
46
These penta-BDE-containing
particulates may then become airborne, explaining the
dominance of penta-BDE congeners reported in passive
sampling of indoor air.
47−49
This may also explain their
accumulation on clothing, whereas BDE-209 has been observed
to reside primarily in settled dust.
48,49
Tetrabromobisphenol A (TBBPA). TBBPA is used primarily
as a reactive FR (i.e., chemically bound to the polymer) in
Figure 2. ClOPFRs and PBDEs in dust and laundry wastewater,
percent composition (mean).
Environmental Science & Technology Article
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printed circuit boards, with approximately 18% used as an
additive FR (no chemical bond) in acrylonitrile butadiene
styrene (ABS) resins and possibly in high impact polystyrene
(HIPS).
21,50
TBBPA was detected in 95% of dust samples (n=
19), with a median level of 209 ng g−1. Levels were highly
variable, with the maximum detection (6560 ng g−1) exceeding
those of BDE-47 (2600 ng g−1) and -99 (5810 ng g−1) and
several other FRs in the dust samples. Dodson et al. also
detected TBBPA in 100% of their 2011 and 94% of 2006 dust
samples.
2
Median levels were similar to our 2012 samples, at
200 ng g−1in the 2011 samples and 260 ng g−1in the 2006
samples (Figure 1c). TBBPA is considered the most heavily
used brominated FR, making up 59% of the total 2001 market,
with U.S. imports and production nearly tripling over the past
11 years (to 53,450 tons in 2012).
33,51
Despite its high usage
and 95% detection rate in the dust samples, TBBPA was not
detected in the laundry water samples. This may be explained
by the Abdallah et al. observation, with a modified passive air
sampler collecting both gaseous and particulate phases. They
detected TBBPA at levels approaching those of BDE-47, but
only in the particulate phase, whereas the lower brominated
BDEs as well as HBCD were detected in both particulate and
gaseous phases.
47
Batterman et al. also detected TBBPA in 90%
of office dust samples, but only in 30% of office air samples.
48
This may be related to TBBPA’s lower vapor pressure,
compared to PBDEs and HBCD, as well as product usage:
since its primary use is reactive, the chemical bond may restrict
its mobility once incorporated into products.
Alternative Brominated Flame Retardants (TBB, TBPH,
DBDPE, and BTBPE). TBB and TBPH were detected in each of
the dust samples (n= 20), a detection rate nearly double that of
a 2002−2007 study of Boston homes.
1
Median levels of TBB
and TBPH, 190 and 115 ng g−1, respectively, were similar to
those in the 2011 California samples taken by Dodson et al.,
but the maximum levels were much higher in the California
study (for TBB, 5900 compared to 1430 ng g−1, and for TBPH,
3800 compared to 435 ng g−1) (Figure 1c). TBB and TBPH are
components of Chemtura products Firemaster 550 and BZ-54,
used in polyurethane foam; another Chemtura product, DP-45,
is used in PVC plastic and other applications and contains
TBPH.
52−54
TBB and TBPH were also detected in 100% of
laundry wastewater samples. Median concentrations were 363
ng L−1for TBB and 445 ng L−1for TBPH. The TBB-related
fraction (ftbb) of the total concentration of TBB plus TBPH
(ftbb = TBB/(TBB + TBPH) was lower in the laundry
wastewater (ftbb = 0.45) than in the dust samples ( ftbb = 0.69)
but similar to that observed in the air over the Great Lakes,
which ranged from 0.26 to 0.54, possibly indicating that TBB
and TBPH on clothing are associated with air levels.
52
A 2012 study of 102 couch foam samples collected from U.S.
households found these FRs in 13 samples, primarily from
couches purchased after the penta-BDE phaseout.
19
Three
studies tested foam from children’s products and found TBB
and TBPH in 17% of 101 items currently in use in 2011, in 5%
of 20 products newly purchased in 2011, and in 52% of
products newly purchased in 2013, indicating this combination
is becoming one of the primary replacements for penta-BDE in
children’s products.
36,37,55
DBDPE, structurally similar to BDE-209, has been marketed
as the replacement for the deca-BDE formulation used as an
additive FR in HIPS, ABS, and polypropylene plastics and in
textiles.
56
Its 2012 U.S. production volume was reported at
22,700−45,400 tons.
33
DBDPE was detected in house dust
from all homes sampled (range 18−490 ng g−1, median 173 ng
g−1), in the same range as for TBB and TBPH. Dodson et al.
also detected DBDPE in all samples, with median values nearly
tripling between 2006 and 2011 (from 51 to 140 ng g−1)
(Figure 1c).
2
BTBPE, another PBDE replacement product (for
octa-BDE), was first introduced in the 1970s and is now used in
ABS, HIPS, thermoplastics, thermoset resins, polycarbonate,
and coatings.
56
Its metabolism may yield the neurotoxic
compound tribromophenol.
57
BTBPE was detected in 80% of
the dust samples, with a range of <1 to 361 ng g−1, somewhat
higher than levels observed by Dodson et al., which ranged
from 3 to 130 ng g−1.
2
Although both DBDPE and BTBPE compounds were found
in household dust from 80% or more of homes and DBDPE
was detected in 74% of laundry wastewater samples, BTBPE
was detected in only 5% of the samples. Median levels of
DBDPE in dust were approximately twice those of BTBPE. A
Swedish dust and air study of five households detected BTBPE
in each dust sample and DBDPE in four but detected DBDPE
in only one air sample.
49
Hexabromocyclododecane (HBCD). The three isomers of
HBCD (α-, β-, and γ-HBCD) were detected in 95% of dust
samples, at levels approximately 1 order of magnitude lower
than PBDEs or ClOPFRs, but higher than other FRs. ∑HBCD
concentrations ranged from <1 to 3160 ng g−1, with a median
concentration of 300 ng g−1, nearly double the Dodson et al.
median values of 190 ng g−1(2006) and 160 ng g−1(2011)
(Figure 1d).
2
In the California study, the dominant
diastereomer detected was γ-HBCD, with median levels 49%
and 46% of median ∑HBCD in 2006 and 2011, respectively; in
our samples, α-HBCD dominated (64% of ∑HBCD) (Figure
1d). The technical product is dominated by the γ-isomer
(>90%), but enrichment to α-HBCD occurs following exposure
of HBCD-treated thermoplastics and textiles to elevated
temperatures (>160 °C), which can occur during product
manufacturing or through biotransformation.
5,58
The primary
uses of HBCD in the home are likely in expanded and extruded
polystyrene foam insulation (EPS and XPS) and to a lesser
extent on upholstery textiles.
20
A signficant shift from γ-toα-
HBCD in dust samples has been observed after exposure to
natural light.
59
Also, spatial variability can affect isomer profiles,
with decreasing γ-HBCD and increasing α-HBCD concen-
trations with distance from HBCD-containing products.
60
Therefore, collection techniques and light exposure may have
contributed to profile variability between these studies.
HBCDs were detected in only 26% of laundry wastewater
samples, with ∑HBCD levels ranging from <1 to 1,270 ng L−1.
The stereoisomer profile of one laundry wastewater sample was
dominated by the γisomer, contributing 80% to ∑HBCD in
that sample (Home 4, Supplementary Table S6). This was
considered an outlier, and when it was removed from the data
set, we observed similar isomer profiles in dust and laundry
wastewater, with α-HBCD contributing 69% and 63% to mean
∑HBCD, respectively.
HBCD has been added to the Stockholm Convention on
persistent organic pollutants because of its persistence,
bioaccumulation, and toxicity, with phaseout under the
Stockholm Convention beginning in 2014.
61,62
The United
States is not a party to the Convention, but the USEPA
initiated an action plan on HBCD in 2010 and recently released
a draft Alternatives Assessment.
63
Wastewater Treatment Plants. To evaluate laundry
wastewater contributions of FRs to the aquatic environment,
Environmental Science & Technology Article
dx.doi.org/10.1021/es502227h |Environ. Sci. Technol. XXXX, XXX, XXX−XXXE
influent and effluent were collected from two WWTPs, Marine
Park and Three Rivers, WA, and analyzed for FRs. These
WWTPs serve predominantly households (>80%), with some
industry discharges, none of which are known FRs dischargers,
and service the communities where the dust and laundry
wastewater samples were collected. Both utilize activated sludge
treatment and process approximately 10 million gallons per
day. Three PBDE congeners (∑3PBDE: BDE-47, -99, and
-209), TBB, TBPH, DBDPE, and three ClOPFRs (TCEP,
TCPP, and TDCPP) were detected in influents. The ClOPFRs
were present at by far the highest levels, with mean influent
levels of individual compounds ranging from 393 to 3,440 ng
L−1;∑ClOPFRs were 6,140 ng L−1at Marine Park and 1,680
ng L−1at Three Rivers. ∑3PBDEs were detected in influent at
206 ng L−1at Marine Park and 35.0 ng L−1at Three Rivers. In
effluent, two PBDEs (∑2PBDE: BDE-47 and -209), TCEP,
TCPP, and TDCPP were detected. Effluent ∑2PBDE levels
were 28.2 ng L−1at Marine Park and below detection at Three
Rivers. Effluent ∑ClOPFRs were 11,800 ng L−1at Marine Park
and 2,900 ng L−1at Three Rivers (Supplementary Tables S7
and S8).
These levels of ClOPFRs are somewhat higher than those
found by the USGS at nine WWTPs discharging to the
Columbia River in 2008−09. TCEP in those effluents ranged
from 160 to 650 ng L−1, compared to our results of 814 and
563 ng L−1at Marine Park and Three Rivers, respectively
(Supplementary Tables S7 and S8). TDCPP in USGS samples
ranged from 120 to 690 ng L−1, compared to our results of
3,250 and 579 ng L−1(Supplementary Tables S7 and S8). The
USGS study did not include TCPP, but it was measured in
WWTP effluents and surface water of the Rhine Valley in
Germany.
30
Effluent levels of ClOPFRs in that study typically
ranged from 5 to 400 ng L−1, with TCPP at the highest
concentrations, and surface water samples varied from 13 to
310 ng L−1, with TCPP again at the highest concentrations.
TCEP and TCPP were also detected along California’s San
Francisco Bay and the Southern California Bight, with mean
concentrations of 410 and 7.6 ng L−1, respectively.
64
Indicating
resilience to treatment, these ClOPFRs were also detected in
the source water and finished drinking water of eight U.S. water
utilities, with median drinking water concentrations of TCEP
and TCPP at 120 and 210 ng L−1, respectively.
65
PBDE concentrations were substantially lower in effluent
than in influent; previous studies indicate that PBDEs partition
primarily to sewage sludge.
26
No PBDEs were detected in the
effluent from the Three Rivers plant, and the Marine Park plant
showed an 86% removal rate (Figure 3; Supplementary Table
S7). High removal rates (100%) were also observed for TBB,
TBPH, and DBDPE. By contrast, there was an increase in
TCEP, TDCPP, and TCPP levels at Three Rivers; at Marine
Park, TCPP increased, and TCEP and TDCPP decreased
slightly (Figure 3; Supplementary Tables S7 and S8). Although
treatment retention times were taken into account during
collection, similar observations have been reported and
presumed to result from fluctuations in influent concen-
trations.
66−68
Alternative explanations could include analytical
interference from the complex influent matrix.
To gain a general understanding of the importance of
laundry water in contributing FRs to WWTP influent, estimates
were generated of expected levels of FRs if laundry wastewater
were the sole source. To create these estimates, we multiplied
the median level of the compound by 7.8% to account for the
proportion of influent from laundry water and by 81%
(obtained from each WWTP) to account for the proportion
of influent from residences.
69−71
Interestingly, the estimates
generated are comparable to measured mean influent
concentrations at the two WWTPs (Figure 3a,b; Supplemen-
tary Tables S7 and S8). Based on these observations, laundry
wastewater may well be a primary source of these FRs to
WWTP influent and for ClOPFRs, with their ability to resist
treatment, to the aquatic environment.
Estimated mass loadings to the Columbia River were
calculated using average yearly discharge from the WWTPs
sampled. The highest estimated loadings were for TCPP, at 114
and 22.1 kg/year, and TDCPP, at 48 and 7.3 kg/year, followed
by TCEP, at 12 and 7.1 kg/year, from Marine Park and Three
Rivers, respectively. Considering that the U.S. generates more
than 85 trillion liters of wastewater annually, if the effluent
levels detected at these plants represent WWTP loadings
nationally, approximately 402,000 kg of TCPP, or 2% of its
annual production, and 174,000 kg of TDCPP, or 1−4% of its
annual production, are being discharged annually to the aquatic
environment. This was also observed in a Swedish study,
reporting influent loadings representing up to 5% of
compounds’reported use.
66
While PBDE levels in house dust were approximately one-
third of ClOPFR levels, PBDEs were present at comparatively
low levels in laundry wastewater and WWTP influent and even
lower in effluent. ClOPFRs, on the other hand, were found at
the highest concentrations in house dust and were also present
at relatively high levels in laundry wastewater as well as WWTP
influent and effluent. These data indicate that several factors
affect the transfer of FRs from products in the home to WWTP
effluent and ultimately waterways. First, use patterns determine
the extent to which the compound is present in the household
dust and air. Second, our results suggest that hydrophilic
compounds accumulate at a higher rate in laundry wastewater.
Finally, a number of studies have demonstrated that
compounds that are highly soluble, resilient to microbial
Figure 3. (a,b) Flame retardants in wastewater treatment plant
influent and effluent and estimated flame retardant contribution of
laundry wastewater to influent (*removal rate < 16%).
Environmental Science & Technology Article
dx.doi.org/10.1021/es502227h |Environ. Sci. Technol. XXXX, XXX, XXX−XXXF
degradation, or with low partitioning coefficients (e.g., log Kow
< 2) are inefficiently removed during wastewater treatment and
thus discharged into aquatic environments.
26,72
The three ClOPFRs identified here, the compounds found at
by far the highest levels in the wastewater effluent, combine all
of these factors, making them more likely to be present in
discharges to the environment. Some are high production
volume compounds, used in many products in the home in an
additive fashion, and have been shown to be resilient to
wastewater treatment.
While this study was somewhat limited in sample size, with
20 homes sampled, the variety of compounds analyzed
provided an opportunity to investigate factors affecting transfer
of a range of FRs with varying chemical properties including
solubility. These findings should inform public policy on use of
FRs in products in the home by highlighting transfer of these
compounds to waterways such as the Columbia River.
■ASSOCIATED CONTENT
*
SSupporting Information
Detailed instrument methodology, QC/QA, and individual FR
results. This material is available free of charge via the Internet
at http://pubs.acs.org.
■AUTHOR INFORMATION
Corresponding Author
*Phone: 206-632-1545 x119. Fax: 206-632-8661. E-mail:
eschreder@watoxics.org.
Notes
The authors declare no competing financial interest.
■ACKNOWLEDGMENTS
This paper is Contribution No. 3387 of the Virginia Institute of
Marine Science, College of William & Mary. The authors wish
to thank the study participants, the volunteers who assisted in
sample collection, and Dr. Hiro Tamura and Lorelei Walker for
their assistance in data analysis and gratefully acknowledge the
support of Columbia Riverkeeper.
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