Fabrics and Semi-volatile Organic Compounds: Towards Understanding Accumulation and Release
by
Amandeep Saini
A thesis submitted in conformity with the requirements for the degree of Doctor of Philosophy
Graduate Department of Physical and Environmental Sciences University of Toronto Scarborough
© Copyright by Amandeep Saini 2016
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Fabrics and Semi-volatile Organic Compounds: Towards
Understanding Accumulation and Release
Amandeep Saini
PhD thesis
Department of Physical and Environmental Sciences University of Toronto Scarborough
2016
Abstract
The main goal of this thesis was to improve understanding of the role of clothing in human and
environmental exposure to semi-volatile organic compounds (SVOCs) by characterizing their
accumulation and uptake kinetics to fabrics followed by release in laundry water. Cotton, rayon
and polyester were used as test fabrics and halogenated and organophosphate flame retardants
(HFRs and OPEs, respectively) and phthalates were test chemicals. Analytical and measurement
methods were first developed for quantifying the uptake of SVOCs from indoor air to two
passive air samplers. Distribution coefficients and uptake kinetics of HFRs and phthalates for
cotton, rayon and polyester under ambient indoor and controlled conditions showed gas- and
particle-phase accumulation. Uptake appeared to be air-side controlled when normalized to
planar surface area, with uptake rates of SVOCs of 0.4–0.9 m3 air equivalent/day.dm2 fabric.
These rates imply that 2 m2 of typical clothing worn by a person would sequester chemical in
100 m3 of equivalent air per day due to the large capacity of fabrics to accumulate SVOCs, with
times to reach equilibrium of >10 years for HFRs. An inverse relationship was found between
accumulation by cotton versus polyester and KOW when OPEs, HFRs and phthalates were
considered, indicating the need to consider physical-chemical properties of polar and non-polar
chemicals and fabrics. Chemical release during laundering was a function (sigmoidal) of KOW
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with >80% and <10% loss of OPEs and HFRs, respectively, from cotton and polyester, which
equates to release of 300, 2 and 500 mg of phthalates, PBDEs and OPEs, respectively, per
laundry load to waste water. This research shows the importance of fabrics as indoor sinks for
SVOCs and that fabrics can convey indoor SVOCs to outdoor surface waters via waste water.
The results also have implications for the role of clothing to reduce or enhance dermal exposure
to SVOCs.
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Acknowledgments The journey of earning a doctorate is a long roller coaster of up and down times; immeasurable appreciation is extended to lots of people who helped me in one or another way in making this journey possible. I express deep gratitude to my supervisor, Prof. Miriam Diamond for giving me an opportunity to be a part of her wonderful research group and for her constant encouragement, valuable suggestions and support throughout my research. I am also very thankful to all my committee members Prof. Myrna Simpson, Dr. Rachel McQueen, Dr. Tom Harner and Prof. Frank Wania (ex-member) for graciously offering their valuable time, thoughtful insights and advice. I thank Prof. Jeffery Siegel, Prof. Jennifer Murphy and Dr. Liisa Jantunen for serving on my defence and for constructively reviewing my thesis. Huge thanks to administrative staff of department of Physical and Environmental Sciences, especially to Shelley Eisner (thanks for responding to tons of my emails when I was applying for PhD from India) and Elaine Pick (you always kept me on track to meet the program requirements). Thanks to Dr. Nathalie Tufenkji for BET analysis of fabrics, Dr. Mark Parnis for COSMO-RS measurements, Dr. Rachel McQueen for fabric density measurements and Dr. Ronald Soong and Prof. Myrna Simpson for NMR analysis of fabrics. I am also grateful to Dr. Stuart Harrad, University of Birmingham UK, who gave me a great opportunity to work in his research group on a secondment as part of the EU-funded INTERFLAME project. I also appreciate the guidance and help provided by Dr. Cassandra Rauert (then doctoral candidate), to carry out my research there and cheers to whole group for the good times in Birmingham. A special thank goes to Dr. Emma Goosey (then postdoc) who mentored me very patiently in the beginning of my PhD and handled my hundreds of, sometimes gibberish, questions. How can I not mention my ‘Kanchi’ Golnoush Abbasi and cheer-cum-spiritual leader Joe Okeme; you guys made my journey awesome with your unconditional friendship and support. Golnoush, thanks for all those morning coffees (you made me start drinking coffee!) and yummy foods that we shared. Joe, you were also an amazing office-mate who always boosted me morally during tough times. I also acknowledge selfless help and support of Diamond group’s current (Bella, Yuchao, Jimmy, Clara and Suman) and previous members and thank you all for the cheerful memories that I will cherish for rest of my life. This acknowledgement would be missing its heart without mentioning the unconditional love and support of my husband Amer and my parents-in-law. Their love, encouragement and belief made it possible for me to achieve this goal. Blessings of my parents and family living thousands of miles far in India always made me stronger; not to forget, all those cute photos and videos of my little niece ‘Amreen’ always put a smile on my face. My old but gold friends (Kiran, Rupinder and Jagrup), though continents apart, we always laughed on our research-fever through never ending chats. Last but not least, this thesis is dedicated to my late grandfather ‘Dhanwant Singh’; you had dreamt of seeing me achieving this goal one day, I am living your dream today. You are always with me in spirit and showering your blessings from heaven. I wish you were here among us today. Once again, thank you all from bottom of my heart!
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Table of Contents
Abstract……………………………………………………………………………………………ii Acknowledgments .......................................................................................................................... iv
Table of Contents ............................................................................................................................ v
List of Tables ................................................................................................................................. ix
List of Figures ................................................................................................................................. x
List of Appendices ........................................................................................................................ xii
Abbreviations ............................................................................................................................... xiii
Chapter 1: Introduction and literature review ................................................................................. 1
1.1 Motivation ........................................................................................................................... 1
1.2 Fabrics ................................................................................................................................. 1
1.3 Study chemicals: flame retardants and plasticizers ............................................................ 3
1.3.1 Polybrominated diphenyl ether (PBDEs) ................................................................ 3
1.3.2 New flame retardants (NFRs) ................................................................................. 4
1.3.3 Organophosphate esters (OPEs) ............................................................................. 5
1.3.4 Phthalates ................................................................................................................ 5
1.4 Sources in indoor environment ........................................................................................... 6
1.5 Human health effects of flame retardants and phthalates ................................................... 7
1.6 Human exposure ................................................................................................................. 8
1.6.1 Dietary exposure ..................................................................................................... 8
1.6.2 Dust ingestion and inhalation .................................................................................. 9
1.6.3 Dermal absorption ................................................................................................... 9
1.6.4 Dermal exposure via clothing ............................................................................... 10
1.7 Sorption phenomenon ....................................................................................................... 11
1.8 Research goal and objectives ............................................................................................ 12
References ..................................................................................................................................... 16
Chapter 2: Calibration of two passive air samplers for monitoring phthalates and brominated
flame-retardants in indoor air. .................................................................................................. 27
2.1 Introduction ....................................................................................................................... 27
2.2 Experimental method ........................................................................................................ 30
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2.2.1 Passive air sampling .............................................................................................. 30
2.2.2 Active air sampling ............................................................................................... 31
2.2.3 Extraction and analysis ......................................................................................... 31
2.2.4 QA/QC .................................................................................................................. 32
2.3 Results ............................................................................................................................... 32
2.3.1 Active air sampler ................................................................................................. 32
2.3.2 Passive air samplers .............................................................................................. 34
2.3.3 Fingerprinting ....................................................................................................... 37
2.3.4 Sampling rates of SIPs and PUFs ......................................................................... 37
2.4 Discussion ......................................................................................................................... 39
2.5 Conclusions ....................................................................................................................... 41
References ..................................................................................................................................... 42
Chapter 3: Characterizing the sorption of polybrominated diphenyl ethers (PBDEs) to cotton
and polyester fabrics under controlled conditions. .................................................................. 46
3.1 Introduction ....................................................................................................................... 46
3.2 Experimental method ........................................................................................................ 48
3.2.1 Test material .......................................................................................................... 48
3.2.2 Test chambers ....................................................................................................... 48
3.2.3 Extraction and analysis ......................................................................................... 50
3.2.4 QA/QC .................................................................................................................. 50
3.2.5 Nuclear Magnetic Resonance (NMR) analysis ..................................................... 50
3.2.6 Scanning Electron microscopic (SEM) images .................................................... 51
3.2.7 Density and thickness measurements .................................................................... 51
3.2.8 Specific surface area (SSA) measurements .......................................................... 52
3.3 Results ............................................................................................................................... 52
3.3.1 NMR spectra ......................................................................................................... 52
3.3.2 SEM images, density and specific surface area .................................................... 53
3.3.3 Recoveries of PBDEs from chambers ................................................................... 54
3.3.4 Sorption of PBDEs to cotton and polyester .......................................................... 55
3.3.5 Distribution coefficient, K’D (Cfabric ( or steel)/Cchamber air) ......................................... 59
3.4 Discussion ......................................................................................................................... 61
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3.5 Conclusions ....................................................................................................................... 63
References ..................................................................................................................................... 64
Chapter 4: Characterizing the accumulation of semi-volatile organic compounds to fabrics in
the indoor environment ............................................................................................................ 67
4.1 Introduction ....................................................................................................................... 67
4.2 Experimental method ........................................................................................................ 69
4.2.1 Test materials ........................................................................................................ 69
4.2.2 Home and office deployment ................................................................................ 70
4.2.3 Chemical uptake study .......................................................................................... 70
4.2.4 Extraction and analysis ......................................................................................... 70
4.2.5 QA/QC .................................................................................................................. 71
4.2.6 Data analysis ......................................................................................................... 72
4.2.7 Scanning electron microscopic (SEM) images ..................................................... 72
4.2.8 Density and thickness measurements .................................................................... 72
4.3 Results ............................................................................................................................... 73
4.3.1 Physical features ................................................................................................... 73
4.3.2 SVOC sorption to fabrics from indoor air ............................................................ 73
4.3.3 Uptake rates of SVOCs to fabrics ......................................................................... 76
4.3.4 Fabric-air partitioning ........................................................................................... 79
4.4 Discussion ......................................................................................................................... 82
4.5 Conclusions ....................................................................................................................... 84
References ..................................................................................................................................... 85
Chapter 5: From clothing to laundry water: Investigating the fate of semi-volatile organic
compounds sorbed to fabrics. ................................................................................................... 90
5.1 Introduction ....................................................................................................................... 90
5.2 Methods ............................................................................................................................. 92
5.2.1 Test fabrics ............................................................................................................ 92
5.2.2 Experimental design .............................................................................................. 92
5.2.3 Laundering, drying, extraction and analysis ......................................................... 92
5.2.4 QA/QC .................................................................................................................. 94
5.3 Results ............................................................................................................................... 95
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5.3.1 Chemical accumulation by fabrics normalized to planar surface area (group 1) . 95
5.3.2 Chemical release to laundry water (group 2) ........................................................ 98
5.3.3 Effect of drying (group 3) ................................................................................... 100
5.3.4 Chemical accumulation and release as a function of physical-chemical
properties ............................................................................................................. 101
5.4 Discussion ....................................................................................................................... 104
5.5 Limitations and Uncertainties ......................................................................................... 108
5.6 Conclusions ..................................................................................................................... 109
References ................................................................................................................................... 111
Chapter 6: Conclusion ................................................................................................................. 117
6.1 Summary of the research ................................................................................................ 117
6.2 Major findings ................................................................................................................. 121
6.3 Recommendations for future work ................................................................................. 124
References ................................................................................................................................... 127
Appendices .................................................................................................................................. 129
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List of Tables Table 2.1: Sampling rates, R (m3/day) of SIPs and PUFs for phthalates and flame-retardants, respectively………………………………………………………………………………………38
Table 3.1: Average measured chamber air concentrations and planar area-normalized distribution coefficients (pg/m2 fabric or chamber to pg/m3 air concentration; K’cotton-air, K’polyester-air, and K’steel-air m) at room temperature (one week), and 40°C and 60°C (72 hours)…………………..60
Table 4.1: Uptake rates (m3/day.dm2 fabric) of HFRs by cotton and rayon. (Note: planar surface area was used to normalize uptake rates)………………………………………………………...78
Table 6.1: Summary of findings of fabric experiments reported in Chapters 3, 4 and 5……….123
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List of Figures Figure 2.1: Uptake profile of phthalates by partially and fully sheltered SIPs over 35 days of sampling (summer 2012 campaign)……………………………………………………………...35
Figure 2.2: Uptake profile of flame-retardants by partially and fully sheltered PUFs over 49 days of sampling (fall 2013 campaign)………………………………………………………………..36
Figure 3.1: Solid-state 13C NMR spectra of polyester and cotton. Chemical shift assignments correspond to: a) mid-chain CH2 groups, b) CH2 groups adjacent to COOH groups, c) aromatic carbon, d) carboxylic carbon, e) hexose ring carbons in cellulose, f) hexose ring carbons in cellulose closer to O, and g) anomeric carbon in cellulose………………………………………53
Figure 3.2: SEM images of cotton and polyester fabrics (top) under 30× magnification and single strand structure (bottom) under 2000× magnification……………………………...……………54
Figure 3.3: PBDEs sorbed to cotton and polyester expressed per cm2 planar surface area in chambers without air flow at 40°C and 60°C after 24 hours (error bars show maximum and minimum concentration)…………………………………………………………………………56
Figure 3.4: PBDEs sorbed to cotton and polyester expressed per cm2 BET-SSA in chambers without air flow at 40°C and 60°C after 24 hours (error bars show maximum and minimum concentration). Note: Y-axis is a log scale………………………………………………..……..56
Figure 3.5: PBDEs sorbed to cotton and polyester expressed per gram of fabric in chambers without air flow at 40°C and 60°C after 24 hours (error bars show maximum and minimum concentration)…………………………………………………………………………………….57
Figure 3.6: PBDEs sorbed to cotton and polyester per cm2 planar surface area of fabric in experiments with air flow (error bars show maximum and minimum concentration)…………...58
Figure 3.7: PBDEs sorbed to cotton and polyester expressed per cm2 BET-SSA of fabric in chambers with air flow (error bars show maximum and minimum concentration). …………….58
Figure 3.8: PBDEs sorbed to cotton and polyester per gram of fabric in experiments with air flow (error bars show maximum and minimum concentration)……………………………………….59
Figure 4.1: Accumulation of phthalates (a), PBDEs (b) and NFRs (c) to cotton and rayon fabrics as percentage contribution of each chemical (left Y-axis) and total concentration (right Y-axis) expressed as median (triangle) and geometric mean (circle). Concentrations expressed according to planar surface area. Error bars represent 1st and 3rd quartiles………………………..………..74
Figure 4.2: Uptake profiles of flame retardants by cotton (blue triangles) and rayon (red squares) over 56 days of deployment…………………………………………………...…………………77
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Figure 4.3: Comparison of measured and modeled cellulose-air distribution and partition coefficients plotted as a function of Log KOA. Log KOA values were taken from EPI Suite 4.1 (USEPA, 2012) for NFRs and Harner and Shoeib (2002) for PBDEs…………………………..80
Figure 5.1: Average concentrations of phthalates (a), HFRs (b), and OPEs (c) accumulated by cotton and polyester, expressed as ng/dm2 planar surface area of fabric. Error bars indicate standard deviation. Note: Y-axis is a log scale for HFRs and OPEs but is linear for phthalates. * represents a statistically significant difference between cotton and polyester (p<0.05). Note: TCiPP is referred as TCPP-1………………………………………………………………….…97
Figure 5.2: Percentage distribution of chemicals released to laundry water and remaining sorbed to cotton (top) and polyester (bottom). Percentages are based on concentrations in laundry water (ng/L.dm2) and remaining on fabric (ng/dm2)…………………………………………….……99
Figure 5.3: Concentrations of DBDPE in pre-cleaned and deployed fabrics dried for 20 minutes in an electric dryer (a), and lint collected from the lint trap of dryer (b). Note: Single lint sample was collected for each of cotton and polyester.…………………………………………….…..101
Figure 5.4: Difference in chemical accumulation from air (Ccotton – Cpolyester)/Ccotton, normalized to planar surface area of fabric, plotted against octanol-water partition coefficient (Log KOW). Red dotted line indicates zero on vertical axis. Note: TCEP, being an outlier, was excluded; if included, gives r2 =0.4, p<0.001)…………………………………………………….................102
Figure 5.5: Percentage of accumulated chemical released to laundry water from cotton (blue diamonds) and polyester (red squares) as a function of (a) octanol-water partition coefficient (KOW), and (b) polarizability of eight chemicals. Black, purple and green ellipses enclose phthalates, HFRs and OPEs, respectively……………………………………………………....103
Figure 5.6: The difference of chemical accumulation from air (Ccotton – Cpolyester)/Ccotton, normalized to planar surface area of fabric, plotted against the percentage released to laundry water. The dotted red line indicates zero on horizontal axis…………………………………………………...…………..……………………………..104
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List of Appendices Appendix 1: Supplementary information for Chapter 2………………………………………..129
Appendix 2: Supplementary information for Chapter 3………………………………………..144
Appendix 3: Supplementary information for Chapter 4………………………………………..152
Appendix 4: Supplementary information for Chapter 5………………………………………..165
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Abbreviations ATE/TBP-AE: Tribromophenyl allyl ether AAS: Active air sampler BEH-TEBP: Bis(2-ethlyhexyl)tetrabromophthalate BET: Brunauer-Emmett-Teller BFR: Brominated Flame Retardant BzBP: Benzyl butyl phthalate ClOPE: Chlorinated Organophosphate Ester CV: Coefficient of Variation DBDPE: Decabromodiphenylethane DCM: Dichloromethane DEP: Diethyl Phthalate DEHP: Di (2-ethylhexyl) phthalate DiBP: Di isobutyl phthalate DiNP: Di isononyl phhalate DnBP: Di-n-butyl phthalate DP/DDC-CO: Dechlorane plus EHDPP: 2-ethylhexyl-diphenyl phosphate EH-TBB: Ethylhexyl-tetrabromobenzene FR: Flame Retardant GC: Gas Chromatography GFF: Glass Fibre Filter HBB: Hexabromobenzene HFR: Halogenated flame retardant IDL: Instrument Detection Limit KOA: Octanol-air partition coefficient KOW: Octanol-water partition coefficient LOD: Limit of Detection LOQ: Limit of Quanitfication MS: Mass Spectrometry MTC: Mass Transfer Coefficient NFR: Novel/New Flame Retardant NMR: Nuclear Magnetic Resonance OBIND/OBTMPI: Brominated trimethylphenyl indane OPE: Organophosphate Ester PAS: Passive air sampler PBBz: Pentabromobenzene PBDE: Poly Brominated Diphenyl Ether PBT: Pentabromotoluene PUF: Polyurethane foam disk RSD: Relative Standard Deviation RH: Relative humidity SEM: Scanning Electron Microscope SIP: Sorbent impregnated PUF SRM: Standard Reference Material SSA: Specific surface area
xiv
SVOC: Semi-volatile Organic Compound TCEP: Tris(2-chloroethyl) phosphate TCPP: Tris(2-chloroisopropyl) phosphate TDCiPP: Tris(1,3-dichloroisopropyl) phosphate TnBP: Tributyl phosphate TPhP: Triphenyl phosphate TSF: Teflon Separatory funnel VOC: Volatile Organic Compound VP: Vapour pressure WWTP: Waste water treatment plant
1
Chapter 1: Introduction and literature review
1.1 Motivation
Clothing is a ubiquitous and essential part of modern life. It is in intimate contact with skin and is
close to our breathing zone. From anecdotal evidence, we know that clothing accumulates odours
(volatile organic compounds, VOCs) from the surrounding environment and releases them even
after the removal of the source. The most common example is related to cooking when our
clothing smells like food as it accumulates the odorous chemicals while cooking and then
releases those chemicals after cooking is completed.
Our indoor environment has higher levels persistent organic pollutants (POPs) and other semi-
volatile organic compounds (SVOCs) than outdoors because of the presence of these chemicals
in consumer and building products (e.g., Abbasi et al., 2016; Dodson et al., 2015; Stapleton et al.,
2011). The logical applicability of the phenomenon of sorption-desorption of ‘cooking odour
chemicals’ to clothing can be related to POPs and SVOCs with indoor sources. The sorption-
desorption process undoubtedly follows basic thermodynamic principles dictated by the
physical-chemical properties of the chemical and sorbent, as well as their fugacities in the air-
fabric system.
We also know that exposure to a wide range of the chemicals occurs through dermal sorption
(Moore et al., 2014; Abdallah et al., 2015, 2016; Weschler et al., 2015; Morrison et al., 2016).
Inhalation is another exposure route if the chemical is released from a source in close proximity
of the breathing area. Surprisingly, clothing has not been well investigated as a vehicle or
intermediary of chemical exposure, particularly to SVOCs. My thesis broadly aims to fill this
knowledge gap by investigating the accumulation behaviour of fabrics for a suite of SVOCs
followed by loss of SVOCs from fabrics due to laundering.
1.2 Fabrics
Fabrics or textiles come in many varieties and have many applications. Fabrics are made from
natural and synthetic materials (Mather and Wardman, 2011). Natural fibres are further
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categorized from plant or animal sources, e.g, cellulose fibres like cotton, hemp, and protein
based fibres e.g. wool and silk. Synthetic and semi-synthetic fibres fall into the category of
manufactured fibres. Synthetic fibres are derived from petroleum-based polymers, e.g. polyester,
acrylic. Semi-synthetic fibres such as rayon, also known as regenerated fibres, are modified from
natural sources, like cellulose, in order to impart desirable properties or characteristics (Mather
and Wardman, 2011). The huge demand of fibres, particularly synthetic fibres, has accelerated
their production manifold in past decades. In 2014, cotton and polyester were world’s top two
fibres by demand of 24 and 46 million tons (MT) per year, respectively and by 2030, demand is
projected to reach ~32 and 70 MT (Carmichael, 2015).
Depending on their source, fabrics differ in their physical as well as chemical properties even
within natural (such as cotton versus jute) and synthetic groups (such as nylon versus
polypropylene) (Mather and Wardman, 2011). Fabrics can be characterized on the basis of their
yarn and fabric construction and/or weave, i.e. interlacing the yarn in definitive arrangements
(Mather and Wardman, 2011). Not only the fibres, but their construction to yarn and weave also
determines several physical properties of the fabric like density, surface area and interstices.
Being chemically and physically different, cotton, rayon and polyester were chosen as test
fabrics for different experiments required to fulfil the aim of this thesis.
Flame retardants (FRs) have been added to textiles to increase their resistance to fire and meet
flammability standards (Weil and Levchik, 2008). Information on addition of flame retardants to
clothing or flammability standards for clothing such as children's sleepwear is not readily
available. Other chemicals like nonylphenol ethoxylates (NPEs) or perflourinated compounds are
intentionally added to clothing for purposes such as fabric printing and to confer water repellent
qualities (Herzke et al., 2012; Brigden et al., 2014). The addition of these chemicals to fabrics
has the potential to increase dermal exposure as well as oral exposure in young children (Hughes
et al., 2001). In addition to intentionally added chemicals, fabrics sorb chemicals from the
ambient environment which could also influence human exposure (e.g., Feldman, 2010; Bi et al.,
2015; Morrison et al., 2015).
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1.3 Study chemicals: flame retardants and plasticizers
Flame retardants (FRs) are added to materials to reduce the flammability of broad range of
commercial products like furniture, electronics, and upholstery fabrics (BEARHFTI, 2015).
More than 175 compounds are used as FRs, which are further categorized into organic
halogenated, phosphorus containing, nitrogen containing and inorganic flame retardants
(Birnbaum and Staskal, 2004). In the global production of flame retardants, 25% of the volume is
comprised by halogenated flame retardants or HFRs (other than polybrominated diphenyl ethers
or PBDEs) with about 5% annual growth (Fink et al., 2008).
Depending on their mode of action, FRs can act chemically and/or physically in the solid, liquid,
or gas phase to retard fire. Since, the flammability of a material depends on the fire conditions,
changing the material composition, e.g. with the addition of a flame retardant, also changes its
tendency to burn. For example, the flame retardants that act as a gas-phase quenchers trap the
free radicals that are produced during the combustion process, hence reducing the ability of the
flame to propagate (Alaee et al., 2003). On the other hand, particle-phase quenchers induce the
formation of carbon or a char layer on the burning surface. This layer acts as barrier to heat
transfer and reduces the temperature of the burning surface to a level which is unable to sustain
the combustion process (Alaee et al., 2003; Guerra et al., 2011). FRs are either added to or
reacted with the polymers. Additive FRs have a greater tendency to migrate out of the finished
material and accumulate in the environment (e.g., Sjödin et al., 2003).
FRs are added to a material in order to meet the flammability standards. Technical bulletins
released by California Department of Consumer Affairs, notably TB 117, 117-2013, 129 and
133, are examples of the standards to be met by upholstered furniture (BEARHFTI, 2015).
Consumer products like furniture, electronics and electrical equipment can undergo testing to
meet flammability requirements.
1.3.1 Polybrominated diphenyl ether (PBDEs)
Prior to 2004, PBDEs were one of the most commonly used FRs added to large number of
products ranging from textiles, furniture, electronics and transportation since the 1970s (Abbasi
4
et al., 2015 inter alia). PBDEs were manufactured in three commercial forms – Penta-, Octa- and
Deca-BDE. PBDEs belong to additive category of FRs, hence they are capable of migrating from
treated products over time. They had been reported to constitute a relatively large mass of some
consumer products; for example, Allen et al. (2008) found that televisions had up to 19% by
weight of PBDEs whereas, Hale et al. (2002) reported up to 32% by weight penta-BDE in
polyurethane foam (PUF). Their presence has been detected in wide variety of samples ranging
from bald eagles, herring gulls, lake sediments as well as human serum and breast milk (Li et al.,
2006; Gauthier et al., 2008; Johnson et al., 2010; Letcher and Chu, 2010; Venier et al., 2010;
Siddique et al., 2012). As a result, penta- and octa-BDEs were banned by European Union in
2003 and its production was voluntarily phased out in 2004 in the United States. Canada
restricted the use of penta- and octa-BDE congeners in products in 2008. Penta and Octa BDE
were also added to Persistent Organic Pollutant list of Stockholm Convention in 2009
(Stockholm Convention, 2015). Deca-BDE was restricted in Europe in 2008; the US had aimed
at banning its use from 2013 onwards and Canada was also committed to impose a ban on the
use of Deca-BDE in new products by 2013 (Renner, 2004; Betts, 2008; Environment Canada,
2013; USEPA, 2015).
1.3.2 New flame retardants (NFRs)
With the ban of PBDEs, the demand for alternative FRs increased to meet product flammability
standards. Different phosphatic and halogenated FRs appeared in the market as replacement of
banned FRs. The terms “new” or “novel” or “alternative” FRs (NFRs) have been used for these
chemicals which are new to market or recently observed in the environment (Ali et al., 2011;
Covaci et al., 2011). Some examples of these replacements include decabromodiphenylethane
(DBDPE), 1,2- bis(2,4,6-tribromophenoxy) ethane (BTBPE), bis(2,4,6-tribromophenoxy)ethane
(TBE), Dechlorane plus (DP), 2-Ethylhexyl-2,3,4,5-tetrabromobenzoate (EH-TBB) and bis(2-
ethyl-1-hexyl) tetrabromophthalate (BEH-TEBP). A commercial formulation that has been
widely used to replace penta-BDEs is Firemaster 550 (FM-550) which is mainly composed of
EH-TBB, BEH-TEBP and aromatic phosphate esters (Bearr et al., 2010; Ma et al., 2012).
Similarly to PBDEs, these replacements have been observed in indoor dust, air over Great Lakes
and precipitation, and the Arctic environment (Möller et al., 2011; Salamova and Hites, 2011;
5
Stapleton et al., 2011, 2012; Ma et al., 2012; Shoeib et al., 2012; Cao et al., 2014; Abbasi et al.,
2016). Dechlorane Plus has been detected in human milk, although the levels were two to 10
times lower than that of measured PBDEs (Siddique et al., 2012). As a result of their potential
persistence and bioaccumulative qualities (Zhang et al., 2016), NFRs have also become a matter
of concern with respect to human and environmental health.
1.3.3 Organophosphate esters (OPEs)
Apart from being widely used as pesticides, OPEs are also commonly used as additive FRs,
plasticizers, lubricants and hydraulic fluids (Marklund et al., 2003, 2005; Reemtsma et al., 2008;
Van der Veen and de Boer, 2012). Their use has increased recently with the phase out of PBDEs.
For instance, TDCPP has appeared as one of the major replacements of penta-BDE (Dodson et
al., 2012; Stapleton et al., 2012). Tris dichloropropyl phosphate (TDCPP) is the chlorinated form
of tris (2,3-dibromopropyl) phosphate (Tris-BP), a mutagen banned in 1970s from use in
children’s sleepwear (Blum et al., 1978). TDCPP’s use in foam has been documented in
children’s products such as car seats, crib mattresses and nursing pillows (Stapleton et al., 2011).
A commercial mixture, V6, used in furniture and automobile foam, is reported to be a significant
source of TCEP in the indoor environment (Fang et al., 2013). TCEP, a known carcinogen, has
also been detected in foam samples collected from baby products (EU, 2008; Stapleton et al.,
2011; Fang et al., 2013). Along with consumer products, OPEs have been detected from indoor
to outdoor environments including polar regions, at higher concentrations than PBDEs
(Marklund et al., 2003, 2005; Stapleton et al., 2009; Möller et al., 2012; Cheng et al., 2013;
Abdallah and Covaci, 2014; Salamova et al., 2014; Jantunen et al., 2015).
1.3.4 Phthalates
Phthalate esters (PAEs) are one of the highest production chemicals in the world, primarily used
as plasticizers in polyvinyl chloride (PVC) products, such as furniture, electronic cables and
building materials. Some plastics contain 10-60% by weight of phthalates as they provide
elasticity, transparency and durability to the plastics (Rakkestad et al., 2007). Phthalates are also
used as an additive in wide range of products such as cosmetics, personal care products, waxes,
lubricants and packaging (Kavlock et al., 2002a, 2002b, 2002c; Bornehag et al., 2005; Schettler,
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2006; Koniecki et al., 2011; Romero-Franco et al., 2011; Kim et al., 2013). There are about 60
different types of phthalates manufactured for different usages (Lu et al., 2009). In 2004, global
production of phthalates was estimated at ~6 million metric tonnes per year, of which 80-90%
was used in PVCs (AGPU, 2006). Phthalates are not usually chemically bounded to the materials
to which they are added; therefore they can migrate from the material into the environment.
Phthalates have been found ubiquitously in environmental media such as air, soil, water and
sediments (Bauer and Herrmann, 1997; Xie et al., 2007; Lu et al., 2009; Oyo-Ita et al., 2013),
with their highest levels reported in the indoor environment (Rudel et al., 2003, 2010; Kim et al.,
2013; Orecchio et al., 2013; Dodson et al., 2015).
1.4 Sources in indoor environment
Since HFRs are used as additive FRs in furniture, electronics, wire coatings, roofing, textiles and
upholstery fabrics, these products can act as sources to the indoor environment (Hazrati and
Harrad, 2006; Schecter et al., 2009; Stapleton et al., 2009, 2011; Xian et al., 2011; Allen et al.,
2013; Abbasi et al., 2016). Chemicals are released into air by volatilization followed by
partitioning into dust according to their physical-chemical properties (Shoeib et al., 2012; Rauert
et al., 2015). Release can also occur by abrasion of fine particles from treated polymers and
direct transfer from treated polymer to dust (Webster et al., 2009; Rauert et al., 2014). Prior to
their control, penta-, octa- and deca-BDEs were mainly used in the PUF of upholstered furniture
and vehicle seats, and in electrical and electronic products (Allen et al., 2008; Batterman et al.,
2009; Stapleton et al., 2009; Abbasi et al., 2015). Even after the control of penta- and octa-BDEs
in Canada, the U.S. and Europe, they are still being detected in indoor environments because of
older flame retarded products that remain in use (Abbasi et al., 2015). Elevated concentrations of
NFRs, including TDCPP and FM-550, have been measured in couches and indoor dust in the US
and Canada, which is indicative of their use. FM-550 and TDCPP were also found in 17% and
36% of baby products, respectively, collected from across the U.S. (e.g., nursing pillows, car
seats) (Stapleton et al., 2011). Takigami et al. (2008) found that BFRs migrated from the
television components into the dust and the number of televisions could be used to predict the
content of BDE-209 in house hold dust (Allen et al., 2008). Similarly, Batterman et al. (2010)
found that computer servers were the likely sources of elevated level of PBDE’s in offices in the
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US. Using modelling, Zhang and coworkers estimated that PBDEs were emitted at the rate of 35
and 5.4 ng/h from an old and new computer in an office, respectively (Zhang et al., 2009).
Recently, power consumption of electronics and PBDE levels in indoor air were found to be
positively correlated, suggesting the release of these BFRs due to heat generation from in-use
electronics (Li et al., 2015).
Similarly to FRs, the indoor environment contains a large inventory of phthalates in products and
building materials. The amount of PVC used in flooring and other construction materials was
associated with the levels of BBzP and DEHP present in the dust collected from homes
(Bornehag et al., 2005; Kim et al., 2013). Children’s toys and modeling clays were also found to
contain phthalates (Korfali et al., 2013; Ionas et al., 2014). Sathyanarayana et al. (2008) found
that the use of baby care products like lotion and shampoo were possible sources of phthalate
metabolites found in urine samples of infants, whereas the presence of PVC flooring led to
elevated levels of mono benzyl phthalate (MBzP), the metabolite of benzyl butyl phthalate
(BzBP), in children’s urine samples collected in Sweden (Carlstedt et al., 2013).
1.5 Human health effects of flame retardants and phthalates
The widespread occurrence of FRs and phthalates in indoor environments has raised concerns
related to human health. Various studies have assessed health effects related to flame retardant
exposure to humans and animals (Gascon et al., 2012; Lyche et al., 2015 inter alia). Evidence of
adverse effects comes from epidemiological and toxicological studies. Endocrine disruption is
one of the main adverse effects detected. FRs and phthalates have shown the potential to disrupt
endocrine system by binding to receptors and disrupting receptor signaling (Meerts et al., 2001;
Shen et al., 2011; Heng et al., 2012). In-vivo studies have shown change in spontaneous
behaviour, learning and memory defects, neurotoxicity and neurobehavioural alternations with
exposure to PBDEs, HBCD and OPEs (e.g., Jamal et al., 2002; Mariussen and Fonnum, 2003;
Abou-donia, 2005; Viberg et al., 2006; El-Helaly et al., 2009; Slotkin et al., 2013). Phthalates,
PBDEs and OPEs were also found to cause reproductive effects such as altering semen quality,
delayed onset of puberty and reduced fecundity (Harley et al., 2010; Meeker and Stapleton,
2010; Abdelouahab et al., 2011). Recently, prenatal and childhood exposure to PBDEs in
children was related to poorer attention and reduction in IQ levels in California (Eskenazi et al.,
8
2013). Additionally, TDCPP was found to affect fecundity in zebra fish, when exposed to
environmentally relevant concentrations for 120 days (Zhu et al., 2015).
1.6 Human exposure
Since HFRs and to lesser extent phthalates are hydrophobic, they accumulate in lipid-rich tissues
and exposure can come from dust, diet, air inhalation and dermal absorption as discussed below.
1.6.1 Dietary exposure
The human diet usually contains foods rich in lipids such as fish, poultry, meat, oils and dairy
products. Many of these dietary products have been reported as a contributing factor to increased
human body burdens of FRs and phthalates. Fraser et al. (2009) compared the serum levels of
PBDE’s in vegetarians and omnivores and found 23% higher levels in the later, concluding that
intake of contaminated poultry and meat products contributed to these higher levels. Dietary
intake of PBDEs via fish depends on geographic locations where more fish is consumed. In
North America, Schecter et al. (2006) estimated that fish contributed 10-20% to PBDE exposure
whereas, poultry and processed meat contributed 60-70% of total PBDE’s exposure. In China,
NFRs were reported in farmed fish collected near an e-waste facility but their levels were low
(Shi et al., 2009). OPEs such as TPhP, EHDPP were found in number of food items such as
candy, caramels, margarine, bread and apple sauce in a total diet study conducted by US FDA
(2006). The OPEs likely originated from food packaging.
Phthalates in foods come mainly from processing and handling because they are rapidly
metabolized and hence are not bioaccumulative. High levels of DEHP found in diary product
sampled in the UK, Norway and Spain suggested that milk fat could not be the sole source and
rather collection, transportation or packaging materials contributed to levels (Sharman et al.,
1994). Similarly, food products sampled in Canada and US had considerable levels of DEHP,
DBP and BBP within foods as well as packaging materials (Page and Lacroix, 1989; Schecter et
al., 2013).
For infants, breast milk is the most significant source of exposure to FRs and phthalates (Jones-
Otazo et al., 2005; Main et al., 2006; Gascon et al., 2012). Phthalates and FRs were detected in
9
human milk samples from locations such as Italy, Germany and US (Schecter et al., 2003; Raab
et al., 2008; Latini et al., 2009; Gascon et al., 2012). Siddique et al. (2012) also detected PBDE’s
and Dechlorane Plus in breast milk from women in two Canadian cities (Kingston and
Sherbrooke). These levels of contaminants in breast milk show the potential for exposure of
breast feeding infants. Considering pets as biosentinels for humans, significant levels of PBDE’s
and NFRs were found in serum of pet dogs and cats and in their food, suggesting exposure
through diet and dust (Dye et al., 2007; Venier and Hites, 2011).
1.6.2 Dust ingestion and inhalation
Exposure via inhalation and ingestion of contaminated dust has been reported to substantially
contribute to the overall phthalate and BFR levels in humans (e.g., Jones-Otazo et al., 2005;
Lorber, 2008). Several studies have correlated FRs concentrations in house dust with human
exposure (Wilford et al., 2005; Björklund et al., 2012; Abdallah and Covaci, 2014; Cao et al.,
2014; Stapleton et al., 2014; Hoffman and Stapleton, 2015). In US houses, TDCPP, TCPP and
TPhP were detected in furniture foam and dust indicating the potential for exposure via dust,
particularly for children because of their hand-to-mouth behaviour (Stapleton et al., 2009).
Meeker et al. (2013) found BDCPP, a metabolite of TDCPP, in 91% of urine samples collected
from of a sample of adults. Dust was suspected as the main source of exposure. Similarly, dust
inhalation and ingestion were associated with increase in total daily intake of phthalates in
children (Bekö et al., 2013). In toddlers or young children, dust is considered as the main source
of exposure due to their close proximity to floor or carpet, and their frequent hand to mouth
contact (Jones-Otazo et al., 2005; Stapleton et al., 2008).
1.6.3 Dermal absorption
Dermal exposure to SVOCs occurs through migration of the chemicals from the ambient
environment to skin surface followed by partitioning into skin lipids and finally transfer across
the skin layers to body tissue (Weschler and Nazaroff, 2012). Phthalates, which are used in a
wide range of personal care products, have a high potential for direct absorption through skin.
Koniecki et al. (2011) and Romero-Franco et al. (2011) showed an association between using
personal care products and higher concentrations of phthalates metabolites in the urine of the
10
product users. Recently, Weschler et al. (2015) showed dermal uptake of DEP and DnBP, thus
indicating their direct dermal sorption from air as a significant pathway of exposure. Using the
body patch sampling method, Mäkinen et al. (2009) showed dermal exposure to phosphatic FRs
at five different work places. In an in-vitro study, absorption of 39 to 57% of TDCPP was
reported within 6-12 hours of application directly to skin (Hughes et al., 2001). Direct contact
FR-containing products and dust is also suggested to increase exposure although this could be as
a result of hand-to-mouth transfer (Stapleton et al., 2008, 2014; Watkins et al., 2011).
Dermal exposure of chemicals can be affected by different environmental conditions. Dermal
absorption was observed to increase with the increase of temperature and humidity (Jones, 2003).
Meuling et al. (1997) also observed a relationship between relative humidity, skin moisture and
dermal absorption of the carbamate pesticide Propoxur (absorption increased linearly with
increase in skin moisture).
1.6.4 Dermal exposure via clothing
Exposure of SVOCs through clothing could occur by inhalation of the gas-phase chemicals
released by fabrics or by direct dermal sorption of chemicals by skin lipids from fabrics
(Feldman, 2010; Weschler and Nazaroff, 2012). Recently, Abdallah et al. (2015, 2016) showed
dermal absorption of BFRs and OPEs in human ex vivo skin experiments, suggesting
implications for human exposure. Morrison et al. (2016) showed increased dermal uptake of
phthalates when clothing contaminated with phthalates was worn, whereas, clean clothing
impeded the dermal uptake compared to bare skin. These results indicated the role of clothing in
both enhancing and reducing the dermal exposure depending upon the level of contamination of
clothing itself. Blum et al. (1978) found that Tris-BP, a commonly used flame retardant in
children’s sleepwear in 1970s, was absorbed from treated pyjamas. Blum et al. (1978) also
discussed that washing this sleepwear did not remove the flame retardant. They were not able to
confirm the route of exposure, but it was likely higher for the children who chewed their
sleepwear (Blum et al., 1978). Curwin et al. (2005) reported that clothing worn by pesticide
applicators sorbed glyphostate, triazines and 2,4-D and other pesticides during application
periods and could prolong exposure to the applicators after pesticide spraying through direct
transfer to skin or inhalation of gas-phase pesticides released from clothing to the personal cloud.
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1.7 Sorption phenomenon
Sorption, in simple terms, is a physical-chemical process by which a chemical interacts with
another phase/material. Sorption is driven by the physical-chemical properties of the chemical
(sorbate) and the sorbent material (Schwarzenbach et al., 2003). Sorption can further be divided
into adsorption and absorption based on the degree of interaction between the chemical and the
material. Absorption refers to partitioning of sorbate into the sorbent where as in adsorption,
sorbate interaction is generally restricted to the surface of the sorbent (Schwarzenbach et al.,
2003). Sorption involves molecular interactions such as van der Waals forces, dipole-dipole
interaction, H-bonding as well as electrostatic and ligand exchanges.
Fabrics are heterogeneous matrices depending upon their type. The fabric matrix affects their
physical as well as chemical properties that can ultimately affect sorption. Preferential sorption
of chemicals towards polar or non-polar material including fabrics have been well documented
(Won et al., 2000, 2001; Cieślak, 2006; McQueen et al., 2008; Petrick et al., 2010; Chien et al.,
2011). De Coensel et al. (2008) reported sorption of up to 8-15 mg of moth repellents
(naphthalene, camphor and p-dichlorobenzene) by a 200 g cotton shirt when exposed in a cabinet
for up to 5 days (i.e., 0.04-0.75 mg/g cotton). They suggested that clothing can act as a secondary
source of VOC to the indoor environment after the source is removed. Similarly, after an hour
exposure to methyl salicylate (used to mimic chemical warfare agents) in a sealed wardrobe,
Feldman (2010) observed its release from light clothing such as t-shirts, jeans and fleece jacket
for up to 35 minutes after exposure, and up to 70 minutes from a down-filled jacket. Feldman
reasoned that this difference in release times was because of more contaminated air trapped in
down filled jackets. Piadé et al. (1999); Petrick et al. (2010) and Chien et al. (2011) reported
greater sorption of polar chemicals such as environmental tobacco smoke (ETS) and nicotine to
natural fabrics such as cotton and wool due the polarity and hence greater affinity of the fabrics
for these chemicals. Won et al. (2000, 2001) reported that synthetic carpet (with olefin-based
fibres) and carpet/ polyurethane pad combination had higher sorptive capacities for non-polar
VOCs such as di- and tricholobenzene than more polar VOCs (e.g. isopropanol). Based on the
evidence from these studies, polar and non-polar SVOCs are expected to have greater affinity
towards natural and synthetic fabrics, respectively.
12
1.8 Research goal and objectives
The overarching goal of my study was to improve the understanding of the accumulation and
release behaviour of SVOCs, notably flame retardants and plasticizers, with respect to fabrics. I
hypothesize that clothing accumulates SVOCs from ambient air by gas-phase sorption and
particle-phase accumulation, thereby affecting chemical fate and exposure. The accumulated
chemicals may be released to waste water while laundering, thereby providing a transfer
pathway of SVOCs from indoors to outdoors and thus influencing ecosystem exposure.
Accumulation and release are hypothesized to be driven by the physical-chemical properties of
SVOCs and fabrics.
As discussed in the literature survey, research has been conducted on the accumulation of VOCs
and selected SVOCs by fabrics, however no studies were found that have systematically assessed
fabrics for the accumulation and release of a range of SVOCs. This is an interesting research gap
given the documentation of elevated levels of some SVOCs indoors because of human health
concerns, and the key role played by clothing in indoor and personal environments. The research
presented here aimed to address this research gap by first using controlled experiments to probe
several factors influencing accumulation. Experiments were also conducted under ambient
indoor conditions to further investigate the processes of accumulation and release under
conditions that more closely mimic reality.
This thesis is organized into six chapters, with the first as the introduction and the last presenting
conclusions and recommendations for future work. The research is presented in four chapters of
which one is published and the other three are intended for publication. These four chapters
address the following objectives that were developed to test the hypotheses stated above.
Chapter 2: Calibration of two passive air samplers for monitoring phthalates and brominated
flame-retardants in indoor air.
The goal of this study was to characterize two passive air samplers (PAS), namely polyurethane
foam (PUF) and Sorbent Impregnated PUF (SIP) disks for monitoring phthalates and BFRs in
indoor air. This study facilitated understanding the uptake behaviour of test chemicals using well
characterized PAS. Based on the results of this study, we recommended a generic sampling rate
13
for SIPs and PUFs for monitoring phthalates and BFRs, respectively. This chapter is published in
Chemosphere.
Reference: Saini, A., Okeme, J. O., Goosey, E., and Diamond, M. L. 2015. Calibration of two
passive air samplers for monitoring phthalates and brominated flame-retardants in indoor air.
Chemosphere, 137, 166–173. doi:10.1016/j.chemosphere.2015.06.099
I was responsible for designing the calibration study in consultation with Emma Goosey and
Miriam Diamond. Both Emma Goosey and Joseph Okeme helped with sampler deployment and
retrieval. I was also responsible for laboratory analysis, data analaysis and writing the initial draft
of the paper. All coauthors provided suggestions regarding analysis and interpretation of data and
were also involved in reviewing the manuscript.
Chapter 3: Characterizing the sorption of polybrominated diphenyl ethers (PBDEs) to cotton and
polyester fabrics under controlled conditions.
The goal of this study was to characterize the sorption behaviour of cotton and polyester fabrics
of gas-phase PBDEs under controlled conditions in chamber experiments. I hypothesized that
polyester, being more non-polar than cotton, has greater affinity for PBDEs. The results were
analyzed to evaluate the role of the physical-chemical properties of PBDEs and fabrics. This
study was conducted at University of Birmingham as a part of my secondment in the
INTERFLAME project, a Marie Curie International Research Staff Exchange scheme project
funded by the European Union.
Reference: Saini, A., Rauert, C., Harrad, S., Simpson, M.J. and Diamond, M.L. Characterizing
the sorption of polybrominated diphenyl ethers (PBDEs) to cotton and polyester fabrics under
controlled conditions. Submitted to Science of the Total Environment.
The research was designed and conducted under the supervision of Professor Stuart Harrad
(School of Geography, Earth and Environmental Sciences, University of Birmingham) and then
Doctoral candidate Cassandra Rauert. I was responsible for carrying out the experiment,
laboratory and data analysis under the guidance of Cassandra Rauert. Professor Myrna Simpson
(Department of Physical and Environmental Sciences, University of Toronto at Scarborough)
14
conducted the NMR analysis on samples I prepared and also assisted in writing the NMR section
of the paper. I was responsible for writing the initial draft of the paper with guidance from
Miriam Diamond.
Chapter 4: Characterizing the accumulation of semi-volatile organic compounds to fabrics in
indoor environments.
The goal of this study was to investigate the SVOC accumulation by two cellulose-based fabrics,
cotton and rayon, to test the hypothesis that they have similar uptake kinetics. The chemicals of
interest were phthalates and HFRs. Two sampling studies were conducted to test the hypothesis.
The first study involved fabric deployment in 20 homes and 5 offices to assess sorption after 28
days of exposure. The second study involving fabric deployment for 56 days in one office to
measure weekly uptake kinetics. The results from both studies were used to reflect on the
implications of clothing for the indoor fate of SVOCs as well as human exposure.
Reference: Saini, A., Okeme, J. O., Parnis, J. M., McQueen, R. H. and Diamond, M. L.
Characterizing the accumulation of semi-volatile organic compounds to fabrics in indoor
environments. Submitted to Indoor air.
I was responsible for designing the experiment with guidance from Miriam Diamond. Joseph
Okeme conducted the home and office sampling campaign and also assisted me in sampler
deployment and retrieval in uptake study. I was responsible for developing the single method for
fabric extraction targeting three chemical classes followed by all laboratory and data analysis of
samples. Professor Mark Parnis (Department of Chemistry, Trent University) conducted
COSMO-RS modeling based on my experimental data and provided text related to the model.
Miriam Diamond provided guidance for all aspects of the study and was closely involved with
editing the manuscript.
Chapter 5: From clothing to laundry water: Investigating the fate of semi-volatile organic
compounds accumulated by fabrics.
This goal of this study was to investigate the role of clothing as a sorbent of indoor SVOCs and a
source for transferring accumulated chemicals from indoors to outdoors via release to waste
15
water while laundering. I hypothesized that the physical-chemical properties of chemicals as well
as fabrics control the distribution of chemicals in the air-cloth-laundry system. The results were
assessed to compare accumulation of phthalates and halogenated and organophosphate flame
retardants to cotton and polyester, amount of these SVOCs released to wash water after
laundering, and finally the SVOCs remaining on fabrics after washing. The study also
investigated the role of an electric dryer in adding or removing SVOCs sorbed to fabrics. The
results have important implications of clothing acting as a collector of indoor SVOCs and
conveying them from indoors to outdoors. The results are also discussed in terms of human
exposure.
Reference: Saini, A., Thaysen, C., Jantunen, L., McQueen, R. H. and Diamond, M. L. From
clothing to laundry water: Investigating the fate of semi-volatile organic compounds accumulated
by fabrics. Prepared for submission to Environmental Science and Technology.
I was responsible for designing the experiment, in consultation with all coauthors. Dr. Liisa
Jantunen (Environment Canada) provided expert advice on developing the laboratory methods
for OPE analysis and Dr. Rachel McQueen provided expert assistance on selecting the fabrics.
Clara Thaysen and I conducted the entire experiment including sample preparation and their
laboratory analysis. I was responsible for data analysis and writing the initial draft of the paper
with guidance from Miriam Diamond.
16
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Chapter 2: Calibration of two passive air samplers for
monitoring phthalates and brominated flame-retardants in
indoor air.
2.1 Introduction
Passive air sampling of semi-volatile organic compounds (SVOCs) has gained popularity due to
its cost effectiveness, ease of handling and operation, suitability for use in most locations, and
avoided need of electricity. Shoeib and Harner (2002) developed and popularized the
polyurethane foam (PUF) based passive air sampler (PAS) that now sees global use (e.g., Harner
et al., 2006; Pozo et al., 2009). In addition to PUF-PAS, other media have been used for PAS
such as semi-permeable membrane devices (SPMD) (Petty et al., 1993), XAD resins (Wania et
al., 2003), and polymer coated glass (Harner et al., 2003). Air concentrations are derived from
PAS based on sampling rates, R (m3/d), which correspond to the equivalent air volumes that are
sampled by the PAS. For PUF-PAS, R is obtained through calibration of chemical uptake during
the linear uptake phase, before equilibrium is reached.
While highly convenient, one disadvantage of PUF-PAS is its limited sorptive capacity. This
prompted Shoeib et al. (2008) to coat the PUF with powdered XAD resin which they named
Sorbent Impregnated PUF or SIP. XAD is styrene divinylbenzene copolymer that has a relatively
high sorptive capacity for organic and polar chemicals due to a higher specific retention volume
compared to PUF (Pankow, 1989; Pankow et al., 1996; Hayward et al., 2011). The advantages of
a SIP relative to PUF are related to its high sorptive capacity and applicability to a broader range
of chemicals such as relatively volatile and polar or surface-active chemicals such as
perfluorinated compounds and volatile methyl siloxanes (Shoeib et al., 2008; Ahrens et al., 2013;
Harner et al., 2014).
Although acknowledged to provide semi-quantitative estimates of SVOC air concentrations, one
critical step towards obtaining relatively accurate estimates of air concentrations from PAS is
having well characterized values of R. Several studies have summarized values of R for PAS
deployed outdoors (Chaemfa et al., 2008; Bohlin et al., 2010, 2014a; Melymuk et al., 2011). In
28
turn, having reliable R rests on calibrating PAS under the conditions that correspond to
deployment conditions. For instance, having similar wind speed, to which R is highly dependent,
temperatures and exposure to UV radiation during calibration and deployment are important as
these factors are known to affect chemical uptake (Harner et al., 2003; Wania et al., 2003;
Chaemfa et al., 2009; Melymuk et al., 2014). Harner et al. (2003) introduced the “double bowl”
design to house PUF-PAS to control the influence of precipitation, exposure to UV radiation, and
wind speed. For example, this type of housing minimizes turbulent air flow around the PAS
(Thomas et al., 2006).
With a growing interest in characterizing human exposure indoors, more studies are now
investigating the use of PAS indoors (e.g., Wilford et al., 2004; Bohlin et al., 2014b). Use of PAS
indoors has the advantages of being relatively unobtrusive, quiet and cost-effective if many
homes are sampled (e.g. Wilford et al., 2004; Dodson et al., 2015). In epidemiological studies, a
deployment time of less than 3 months, which is common for outdoor deployments, is desirable
to minimize the inconvenience to study participants. A shorter deployment period can be
enabled, in part, by air concentrations of SVOCs that are typically higher indoors than outdoors
by a factor of 3–10 (Rudel et al., 2003; Bohlin et al., 2014b). Recently, Bohlin et al. (2014b)
reported sampling rates for 60 SVOCs based on the PUF-PAS in the double-bowl design and a
deployment period between 4 and 9 weeks. They commented that one way to maximize uptake
indoors, particularly of particle-sorbed chemicals, would be to minimize the housing around the
PAS, which is possible because of low wind speeds indoors. An example of such a partial
housing is the sheltered tripod stand introduced by Wilford et al. (2004), which has the effect of
maximizing air flow around the PAS while minimizing gravitational deposition of large particles.
The aim of this study was to advance PAS methods to measure indoor air concentrations of
SVOCs. We aimed to do this by characterizing two passive samplers for measuring selected
SVOCs indoors, namely phthalates and brominated flame-retardants or BFRs (polybrominated
diphenyl ethers or PBDEs and “new” flame-retardants or NFRs). Phthalate air concentrations
have been determined via active air sampling (Fromme et al., 2004; Otake et al., 2004; Adibi et
al., 2008; Rudel et al., 2010; Bergh et al., 2011; Dodson et al., 2015) and to best of our
knowledge, have not been measured using SIP- or PUF-PAS. Vapour pressures (VP) and
octanol-air partition coefficients (log KOA) of phthalates assessed here ranged from 10-2–10-5 Pa
29
and 7.6–10.5, respectively (Cousins and Mackay, 2000). Some phthalates are relatively more
volatile among SVOCs for which PAS have been commonly used. With the goal of minimizing
the deployment time, we also tested the effect of housing design on uptake behaviour and
sampling rates in collocated PAS deployed in fully and partially sheltered housing. PAS uptake
rates for phthalates and BFRs were obtained by comparison with active air samples that were
used to measure gas- and particle-phase air concentrations.
A synopsis of the theory of PUF-PAS is given in supporting information, SI (Appendix 1).
Briefly, PUF-PAS were originally assumed to accumulate gas-phase chemicals only through the
migration of gas-phase chemicals into PAS. However, several studies have documented the
presence of fine particles on passive sampling media during both indoor and outdoor deployment
(Hazrati and Harrad, 2007; Chaemfa et al., 2009; Abdallah and Harrad, 2010). In particular,
entrapment of 1–2 µm particles by PUFs deployed outdoors and indoors has been found, even in
fully sheltered housings (Chaemfa et al., 2009; Bohlin et al., 2010). Klánová et al. (2008)
demonstrated that PUF (outdoors) sampled 10% of ambient fine particles as their behaviour is
similar to those of gas-phase chemicals. Harner et al. (2013) reported indiscriminate sampling of
gas- and particle-phase polycyclic aromatic compounds by PUF-PAS deployed outdoors,
whereas, inconsistent sampling of particle-phase chemicals by PUF in fully sheltered housing
deployed outdoors and indoors was observed by Bohlin et al. (2014a,b). Melymuk et al. (2014)
commented that the use of lower density PUF might increase particle uptake during outdoor
deployments. Recently, Markovic et al. (2015) evaluated the particle infiltration efficiency of
three PAS designs, along with an active air sampler (AAS). They found that particles from 250
to 4140 nm were in comparable numbers and size distribution outside and inside GAPS and
LANCS PUF-PAS housings. In response to these observations of PAS sampling particles, many
researchers now calibrate and report sampling rates on the basis of bulk (gas+particle) air
concentrations (Melymuk et al., 2011; Bohlin et al., 2014a,b), which we have done here.
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2.2 Experimental method
2.2.1 Passive air sampling
Summer 2012: To obtain uptake rates for phthalates and BFRs, SIPs and PUF-PAS were
deployed for 35 days in a closed room (restricted access, no mechanical ventilation) with vinyl
tile flooring, located in a 30-year old building at University of Toronto. PUF disks, of size 14 cm
diameter × 1.2 cm thick, with a surface area of 360 cm2 and density 0.021 g/cm3 (PacWill
Environmental, Beamsville, ON, Canada). PUFs were pre-cleaned by extraction in an accelerated
solvent extractor or ASE (Dionex ASE 350) using hexane and dichloromethane, followed by
drying in a vacuum desiccator. To make the SIPs, PUF disks were uniformly coated with
powdered XAD-4 resin (Shoeib et al., 2008). Nine disks of both PUFs and SIPs were deployed in
fully sheltered (double-bowl) housing, with the top being larger than the bottom (Harner et al.,
2003, Figure A1.1). Another nine SIPs were deployed in the partially sheltered, tripod housing
consisting of a tripod stand and top cover only (Wilford et al., 2004), supplied by Environment
Canada (Figure A1.1). PUFs and SIPs in the fully sheltered housing were hung at the height of
1.5 m above ground, with the distance of 1 m between adjacent samplers whereas partially
sheltered SIPs stood on a wooden bench 1 m above ground with 1 m distance between adjacent
stands. Samples were collected on days 0, 7 (2 samplers), 14, 21, 28 and 35 following
deployment.
Fall 2013: PUFs were deployed for 49 days in an office at University of Toronto, again to obtain
uptake rates for phthalates and BFRs. The office was located in a 12 year old building with
industrial carpeting, vinyl office-desks, PUF chairs, computers and electronic equipments. PUF
disks, of the same dimensions as those used in summer 2012, were pre-cleaned using same
method. Thirteen PUFs were deployed in each of fully (double-bowl) and partially sheltered
(with only top bowl) housings (Figure A1.1). All PAS were hung at a height of 1.5 m above
ground. One PUF was collected from both housings weekly and, in addition, a duplicate PUF
was also collected on days 7, 28 and 49 after deployment. The two PUFs collected on the day 7
were composited to increase analytical detection whereas duplicates collected on days 28 and 49
were extracted and analysed separately to check the reproducibility of results.
31
2.2.2 Active air sampling
During both 2012 and 2013 campaigns, a low volume active air pump (BGI 400S, Pacwill
Environmental, Canada) ran continuously throughout the deployment period at a flow rate of 10
L/min. The analytes were collected on a sampling train which consisted of a glass fibre filter
(GFF) to collect particle-phase chemicals followed by a sandwich of two PUF plugs and XAD
resin to sample gas-phase chemicals (Sigma Aldrich, Canada). The sampling train was kept in
line, horizontally with the pump, on a wooden bench 1 m above ground without a shelter.
Samples were collected at weekly intervals on the same schedule as PAS retrieval in order to
generate uptake curves. PUF-XAD and filters were extracted separately to obtain gas- and
particle-phase concentrations, respectively. The second PUF plug at the end of the sampling train
was also analysed separately to check for analyte breakthrough during active sampling; masses
on this PUF plug were less than 10% for assessed chemicals. All the samples collected from
passive and active sampling were kept at -4°C until extraction and analysis. BFR concentrations
from summer 2012 campaign were very low and hence are not discussed further.
2.2.3 Extraction and analysis
All the samples were extracted using ASE. Extracts were cleaned-up using pre-cleaned alumina
(5g) and sodium sulfate (10g) added to ASE cells before adding the sample (Figure A1.2). This
new method of in-cell extraction and clean-up was developed to lower potential contamination of
phthalates by reducing the number of steps followed between extraction and sample analysis.
Hexane and dichloromethane (DCM) (1:1, v/v) (HPLC grade, Fisher Scientific) were used for
extraction followed by reduction of the extracted volume to 0.1 mL under a gentle stream of
nitrogen in a Zymark Turbo-vap. The final volume of 0.5 mL was reconstituted in GC vials using
isooctane (HPLC grade, Fisher scientific). All SIPs and PUFs were analysed for: six phthalates,
14 PBDE congeners spanning from tri- to deca-BDE and 11 NFRs (see Table A1.1 for all names
and CAS numbers). Samples were analysed using an Agilent 6890N gas chromatograph coupled
with Agilent 5975 inert mass-spectrometer (GC-MS). Details of the GC-MS conditions are given
in SI. Instrument detection limits are listed in Table A1.2.
32
2.2.4 QA/QC
Quality assurance/quality control (QA/QC) was considered throughout the sampling campaign
and analytical measurements by monitoring recoveries, blanks and analysis of certified reference
material (see A1, section 5). Surrogate standards were added to each sample before extraction to
check recoveries of phthalates and BFRs. Laboratory and field blanks were extracted and
analysed (spiked with surrogate standards and internal standards) in every batch of 10 samples.
For phthalates, surrogate recoveries were between 60–100% whereas recoveries for flame-
retardants were in the range of 70–130%. All the results that met QA/QC criteria (see A1,
Section 5) were blank and recovery corrected. A chemical value was rejected if its blank value
was higher than 35% of corresponding sample value. Analytical methods for flame-retardants
and phthalates were validated for their accuracy and reproducibility using spiked blanks and
standard reference material (NIST SRM-2585, Figures A1.3–A1.5). Further details on surrogate
and internal standards, method validation, detection limits, detection frequencies and blank
corrections are provided in SI (Section 5).
2.3 Results
Of the total 31 chemicals analysed (6 phthalates, 14 PBDEs and 11 NFRs), 13 chemicals (4
phthalates, 7 PBDEs and 2 NFRs) were detected consistently with detection frequencies of 80–
100% in AAS and PAS samples. The remaining 18 chemicals were measured at low
concentrations or were detected <80% in AAS and/or PAS (Table A1.2); these chemicals are not
discussed further. PBEB and DiNP were not included due to blank contamination. Details of the
results from the in-cell extraction and cleanup method are provided in A1 (Section 5).
2.3.1 Active air sampler
Phthalates had the highest bulk air concentrations among all chemicals, with average
concentration ranging from 17±2.4 to 85±14 ng/m3 air (Table A1.3, Figure A1.6). Rudel et al.
(2003, 2010) similarly observed that phthalates had air concentrations two or three orders of
magnitude higher than other SVOCs in US homes. Phthalate air concentrations measured here
were within the lower range of those reported in the literature (Table A1.3). DnBP had the
33
highest levels with a maximum concentration of 101 ng/m3 compared to 5590 and 1100 ng/m3
reported in residences by Fromme et al. (2004) and Rudel et al. (2010), respectively. BzBP had
the lowest levels amongst the phthalates with a minimum concentration of 14 ng/m3. The lower
levels measured here could be due to our sampling in one room only with minimal use of
personal care products relative to the studies examining concentrations in multiple locations.
Average BFR concentrations ranged from 5.1±2.6 to 809±102 pg/m3 for PBBz and BDE-47,
respectively, which were three orders of magnitude lower than that of phthalates (Table A1.4,
Figure A1.6). After BDE-47, high concentrations were measured of BDE-99 (111±20 pg/m3) and
BDE-28 (65±9.5 pg/m3). BDE-47 and-99 are the main constituents of the penta-BDE
commercial mixture that was used mainly in flexible foam furniture and has been reported
previously at relatively elevated levels indoors, along with BDE-28 (Stapleton et al., 2008, 2012;
Zhang et al., 2011; Björklund et al., 2012; Bradman et al., 2014). The concentrations measured
here are similar to those measured by Zhang et al. (2011) using a low volume air sampler in
another building at the University of Toronto (Table A1.4). However, they are higher than those
reported by Bohlin et al. (2014b) for the Czech Republic, which is consistent with greater use of
penta-BDE in North America than Europe.
Among NFRs, only PBBz and PBT were consistently detected, with levels of 5.1±2.6 and
7.0±1.4 pg/m3, respectively. Other NFRs and higher PBDE congeners such as BDE-154, -183,-
209 were either not detected or had inconsistent and low levels, and hence are not discussed
further.
Air concentrations were relatively stable and did not vary systematically over the 35 and 49 day
deployments in 2012 and 2013, respectively. The largest variations in concentrations were seen
for BDE-17, -153 and PBBz with relative standard deviations (RSD) of 82, 71 and 51%,
respectively, whereas the remaining chemicals had RSD ≤ 20%. For BDE-17 and PBBz, the first
week’s concentration was responsible for the high RSD which, if excluded, reduced the RSD to
< 20%.
Among phthalates, the percentage measured in the gas-phase ranged between 2 and 98%: 98, 95
and 67% of DEP, DnBP and BzBP were found in the gas-phase, respectively, whereas 98% of
34
DEHP was present in particle-phase (Table A1.3). Rakkestad et al. (2007) reported the presence
of DEHP in PM10 and PM2.5 in indoor air in Norwegian residential and commercial buildings,
but contrary to our results, they also found DnBP in the particle-phase. Finding most phthalates
in the gas-phase is consistent with model-based expectations reported by Dodson et al. (2015)
that indoor bulk air concentrations are mainly comprised of gas-phase concentrations for the
chemicals with log KOA ≤ 10 (such as DEP, DnBP and BzBP), above which the particle-phase
dominates.
Detected BFRs ranged from 74–100% in the gas-phase except for only 30% for BDE-153 (Table
A1.4). These results agree with the ranges of 61–83, 77–100 and 64–100% reported by Abdallah
and Harrad (2010), Zhang et al. (2011) and Bohlin et al. (2014b) for BFRs reported here (these
ranges exclude those chemicals not reported here).
2.3.2 Passive air samplers
SIPs: Linear uptake was observed for four and two phthalates for partially and fully sheltered
SIPs, respectively (Figure 2.1). DEP in fully sheltered SIPs appeared to enter the curvilinear
phase by 28th day of sampling. Alternatively, the apparent curvilinear behaviour could be a
sampling or analytical anomaly as the SIPs in the partially sheltered housing should reach
equilibrium faster than fully sheltered housing given the greater air flow in the former. In
comparison to partially sheltered SIPs, fully sheltered SIPs had three times less accumulated
mass of DEP and DnBP and very low levels of BzBP and DEHP. As such, BzBP and DEHP
measured in the fully sheltered SIPs are not discussed further. The accumulation of DEHP by the
partially sheltered SIPs confirmed the accumulation of particle-phase chemicals. These results
are the first to show uptake of phthalates by PAS and suggest that the use of partially sheltered
SIPs could be used for approximating indoor phthalate concentrations.
PUFs: Phthalates uptake on PUF disks showed an ambiguous pattern over time during both
sampling campaigns. These results suggest that SIPs are better suited to phthalates rather than
PUF-PAS.
35
Figure 2.1. Uptake profile of phthalates by partially and fully sheltered SIPs over 35 days of sampling (summer 2012 campaign).
BFR mass increased linearly in both fully and partially sheltered PUFs throughout the 49 day
sampling period in 2013 sampling campaign (Figure 2.2). Duplicates taken on days 28 and 49
showed good repeatability with RSD ranging between 1–35% (except for BDE-99 with average
RSD of 44% among duplicates). Partially sheltered PUFs sequestered three times more mass by
day 49 compared to fully sheltered PUFs. In particular, partially sheltered PUFs accumulated
more mass of chemicals with relatively low VP such as BDE-153, -154, -183, and -209 (uptake
curve shown for BDE-153 for partially sheltered PUF only) compared with fully sheltered PUFs.
36
Figure 2.2. Uptake profile of flame-retardants by partially and fully sheltered PUFs over 49 days of sampling (fall 2013 campaign).
37
2.3.3 Fingerprinting
Relative abundance (expressed as the percentage of each chemical’s mass to the total mass of all
chemicals) of phthalates and BFRs was calculated for SIPs, PUFs and AAS (bulk and gas-phase
only), as explained by Bohlin et al. (2014a, b). Each chemical’s profile from AAS and PAS was
compared using linear regression (Table A1.5). Slopes of ≥ 0.9 provided evidence that all
chemicals accumulated in the SIPs and PUFs with the same abundance as that found in bulk and
gas-phase air concentrations. These results suggest that PAS quantitatively accumulated particle-
phase DEHP relative to that measured by the active air samplers and hence sampling rates
reported here are not expected to bias air concentrations calculated from PAS.
2.3.4 Sampling rates of SIPs and PUFs
Sampling rates, R (m3/day) were calculated by plotting equivalent air volume (ratio of mass of a
chemical accumulated in the PAS and running average of corresponding bulk air concentration
measured with AAS, Equation A1.2) against deployment time (Figures 2.1 and 2.2). Scatter
around the uptake curves was less than 20% for all deployments shown here (except for BDE-99
and -153). Sampling rates of phthalates in partially sheltered and fully sheltered SIPs ranged
from 2.1–5.9 and 0.8–1.2 m3/day whereas sampling rates of BFRs ranged from 2.7–4.3
(excluding BDE-153) and 0.6–1.9 m3/day for partially and fully sheltered housings, respectively
(Table 2.1). The low mass of BDE-153 accumulated on partially sheltered PUFs compared to
other BFRs resulted in its exceptionally low sampling rate. We believe that the sampling rate for
BDE-153 is unreliable because of low chemical accumulation.
The range of sampling rates for fully sheltered PUFs was narrower but in agreement with results
reported for PBDEs and NFRs (Hazrati and Harrad, 2007; Bohlin et al., 2014b) (Table A1.6).
Wilford et al. (2004) reported an average sampling rate of 2.5 m3/day derived from partially
sheltered PUFs for BDE-17, -28, -47, -99, -100 which is ~20% lower than the average sampling
rate (3.1 m3/day) measured here for the same congeners. The agreement between these two sets
of results gives confidence to the rates reported here. The mass transfer coefficient (MTC),
which represents the velocity at which a chemical is deposited onto PAS, was also determined
from sampling rates and the values ranged from 0.07 to 0.19 cm/s for partially sheltered PAS
38
Table 2.1. Sampling rates, R (m3/day) of SIPs and PUFs for phthalates and flame-
retardants, respectively.
Chemical Sampling rate (m3/day) ±
Standard error of slope
r2 Sampling rate (m3/day) ±
Standard error of slope
r2
Phthalates Partially sheltered SIP Fully sheltered SIP DEP (Diethyl phthalate) 2.1 ± 0.13 0.93 0.8 ± 0.06 0.95 DnBP (Di-n-butyl phthalate) 3.5 ± 0.14 0.97 1.2 ± 0.09 0.98 BzBP* (Benzyl butyl phthalate) 5.9 ± 0.42 0.97 -
DEHP* (Di (2-ethylhexyl) phthalate) 2.8 ± 0.30 0.83 - Range 2.1–5.9 0.8–1.2
Brominated flame-retardants
Partially sheltered PUF Fully sheltered PUF
PBBz (Pentabromobenzene) 4.3 ± 0.17 0.97 1.7 ± 0.06 0.98 PBT (Pentabromotoluene) 4.2 ± 0.16 0.97 1.9 ± 0.15 0.82 BDE-17 (2,2',4-Tribromodiphenyl ether) 3.1 ± 0.20 0.92 0.8 ± 0.05 0.93 BDE-28 (2,4,4'-Tribromodiphenyl ether) 3.4 ± 0.22 0.92 0.9 ± 0.03 0.97 BDE-47 (2,2',4,4'-Tetrabromodiphenyl ether) 2.8 ± 0.18 0.92 0.8 ± 0.04 0.94 BDE-66 (2,3',4,4'-Tetrabromodiphenyl ether) 2.7 ± 0.24 0.87 0.6 ± 0.04 0.91 BDE-100 (2,2',4,4',6-Pentabromodiphenyl ether) 3.1 ± 0.24 0.89 1.0 ± 0.08 0.84 BDE-99 (2,2',4,4',5-Pentabromodiphenyl ether) 3.1 ± 0.22 0.89 1.1 ± 0.13 0.73 BDE-153*(2,2',4,4',5,5'-Hexabromodiphenyl ether) 0.6 ± 0.07 0.74 - Range** 2.7–4.3 0.6–1.9
Over all range** (Phthalates and flame-retardants)
2.1–5.9 0.6–1.9
Overall Average (±Standard deviation)
Phthalates 3.6 (±1.6) 1.0 (±0.4)
BFRs** 3.3 (±0.6) 1.1 (±0.4)
*mass accumulated on fully sheltered PUF was either non-detectable or lacked a defined accumulation pattern **excluding BDE-153
39
(excluding 0.02 cm/s for BDE-153) and 0.02 to 0.06 cm/s for fully sheltered PAS (Figure A1.7).
Overall, PAS deployed in the partially sheltered housing had sampling rates and MTC 2–4.5
times higher compared to those for the fully sheltered housing. A similar difference was found
by Hazrati and Harrad (2007) for PCBs and PBDEs for fully sheltered PUFs compared to those
published for unsheltered or partially sheltered housing (Shoeib and Harner, 2002; Wilford et al.,
2004).
The main factor accounting for the difference between sampling rates or MTC obtained from
PAS deployed in fully and partially sheltered housing is likely the lower resistance to gas-phase
uptake onto more exposed PAS medium resulting from a higher air flow rate (Hazrati and
Harrad, 2007; Zhang et al., 2012). This interpretation comes from the work of Thomas et al.
(2006) who used computational fluid dynamic modeling to show differences in air circulation
pattern and boundary layer characteristics around PAS inside partially and fully sheltered PUF-
PAS. Another explanation for higher sampling rates in partially than fully sheltered PAS is
greater particle accumulation by the former. For example, DEHP, of which 98% was in the
particle-phase, had greater accumulation on partially than fully sheltered SIPs.
2.4 Discussion
SIPs performed well for passively measuring indoor phthalates and PUF-PAS performed well for
predominated gas-phase BFRs. Detection of particle-phase analytes such as DEHP, BDE-153, -
183 and -209 on partially sheltered SIPs and PUFs confirms previous observations of particle-
phase accumulation by PAS. Analysis of chemical profiles from PAS found no evidence of
biased accumulation of particle-phase chemicals. However, only two chemicals (DEHP and
BDE-153) found mainly in the particle-phase, were consistently detected on PAS. Nonetheless,
we recommend calibrating PUF- and SIP-PAS using bulk-phase active air concentrations to
avoid overestimation of sampling rates. We also conclude that the sampling rates presented here
will not systematically bias estimated air concentrations of predominantly gas- versus particle-
phase chemicals, at least for DEHP which occurs at relatively high concentrations.
In terms of passively measuring phthalate air concentrations, partially sheltered SIPs performed
well and better than PUF, presumably because of the increased sorptive capacity of PUF
40
conferred by XAD and hence, expand its applicability to wider range of chemicals. However,
SIPs have the practical disadvantage, especially for indoor use, of losing XAD over the
deployment period that was not quantified here.
The housing design of the PAS is an important consideration while sampling indoors. We
recommend using PAS deployed in partially sheltered housing to provide more reliable results
for estimating indoor air concentrations. This recommendation is based on finding sampling rates
of partially sheltered PAS that were 2.5–4 times higher for all analytes and greater capture
efficiency of particle-phase chemicals.
The choice of generic or homolog/group specific- or chemical-specific sampling rates is under
debate (e.g. Harner et al., 2014; Melymuk et al., 2014 inter alia). Hazrati and Harrad (2007) and
Melymuk et al. (2011) recommended homolog/group specific sampling rates for indoor and
outdoor passive air sampling, respectively, to reduce sampling or site-specific influences,
whereas Bohlin et al. (2014b) recommended both generic (for gas-phase chemicals) and
chemical specific (for particle-phase chemicals) sampling rates. We recommend generic
sampling rates of 3.5±0.9 and 1.0±0.4 m3/day for partially and fully sheltered housing,
respectively, for both predominantly gas-phase phthalates and BFRs, although the same rate is
suitable for predominantly particle-phase DEHP. An insufficient number of particle-phase
chemicals were detected in this study to recommend a chemical-specific or generic sampling for
these chemicals. Using a generic sampling rate avoids the inevitable anomalies that arise in
calibration studies that could lead to erroneous results (e.g., Harner et al., 2014). For example, in
this study the sampling rate of BzBP was approximately two times higher than that of DnBP,
both of which have similar vapour pressures (10-3 Pa) and log KOA (8.54 and 8.78, respectively,
Cousins and Mackay, 2000). Unexpectedly high sampling rates within a chemical class have
been reported elsewhere, e.g., p-TBX by Bohlin et al. (2014b) and flouranthene and pyrene by
Melymuk et al. (2011). As always, care needs to be taken in the case of chemicals with
infrequent detection or levels close to the detection limit in order to avoid incorrectly estimating
air concentrations. An example here is BDE-153 that had a sampling rate of 0.6 m3/day, which is
five times lower than recommended generic sampling rate.
41
The recommended value of 3.5±0.9 m3/day for partially sheltered PUF- and SIP-PAS deployed
indoors is similar to the average outdoor sampling rates of 3.5±1.9 m3/day for SVOCs in fully
sheltered PUF-PAS (Bohlin et al., 2014a), 3.9±2 m3/day reported from the loss of depuration
chemicals from PUF-PAS deployed in fully sheltered housing outdoors (Pozo et al., 2006) and
4±2 m3/day obtained from a compilation of studies conducted over the last decade (Harner et al.,
2014). The similarity in sampling rates indoors and outdoors and across chemicals is
encouraging. It tells us that the PAS samples a similar volume of air in these circumstances.
Outdoors, the fully sheltered design minimizes the effect of variable and sometimes high wind
velocities. Indoors, the partially sheltered design is sufficient because of low air velocities and is
advantageous in maximizing the air sampling volume.
2.5 Conclusions
This study adds to the evidence that SIP- and PUF-PAS are promising tools to monitor a wide
range of SVOCs spanning vapour pressures of 10-1 to 10-11 Pa. In particular, the results show that
indoor air concentrations of phthalates can be approximated using partially sheltered SIPs. Since
the chemicals reported here showed clear linear uptake and better uptake performance when PAS
were deployed in single-bowl or tripod housing, we recommend that a one month of deployment
period for PAS in a partially sheltered housing is sufficient for passively measuring SVOCs in
indoor environments. Further, a generic sampling rate of 3.5±0.9 m3/day is recommended for
predominately gas-phase phthalates and BFRs reported here. This rate is indistinguishable from
the generic sampling rate of 4±2 m3/day recommended for outdoor PUF-PAS by Harner et al.
(2014) for a wide range of SVOCs.
Acknowledgements
We thank Dr. Mahiba Shoeib, Environment Canada, for providing the tripod housing. Research
funding was provided by The Allergy, Genes and Environment Network (AllerGen NCE) and
the Natural Sciences and Engineering Research Council of Canada (NSERC).
42
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46
Chapter 3: Characterizing the sorption of polybrominated
diphenyl ethers (PBDEs) to cotton and polyester fabrics
under controlled conditions.
3.1 Introduction
Textiles constitute the largest surface area of all materials indoors (Molander et al., 2012) and
hence are expected to play an important role as a phase into which chemicals emitted indoors
will partition. Textiles, or fibres, can be divided into the categories of natural (e.g., cotton, wool,
linen, silk), synthetic (e.g., many polyesters, nylon, acrylic), and semi-synthetic (e.g., rayon).
Natural fibres tend to be relatively polar and have reactive functional groups (Figure A2.1).
Cotton and linen, being derived from plants, consist of 88–96% cellulose (in raw fibres) with
hydroxyl functional groups on the glucose monomer (Mather and Wardman, 2011). The
cellulose polymer chains participate in hydrogen bonding that can confer a highly crystalline
structure (Mather and Wardman, 2011). Animal-derived wool and silk consist of proteins with
the amide group and polar side chain with -OH groups available for hydrogen bonding. In
contrast, the most popular form of polyester consists of the terephthalic acid monomer that
contains a benzene ring, carbonyl group and an aliphatic chain which together have relatively
low polarity and fewer functional groups available for bonding than natural polymers (Mather
and Wardman, 2011) (Figure A2.1).
Fibres also differ in their physical morphology. Cellulose fibres, from the cotton seed, have an
irregular and convoluted surface. In contrast, the artificial spinning of a polymer, including
cellulose in the case of rayon, gives it a more uniform surface morphology (Mather and
Wardman, 2011). Thus, natural fibres that have not been artificially spun, have a larger micro-
surface area than synthetic fibres and natural fibres that have been artificially spun. The greater
surface area of natural, non-artificially spun fibres may offer more binding sites for the sorption
of organic compounds. Apart from surface morphology, fibres also differ in degree of
polymerization and crystallinity of structure which can also affect the availability of binding
sites.
47
Differences in the properties of fabrics and other indoor surfaces have been investigated for their
propensity to sorb chemicals. For instance, Piadé et al. (1999), Noble (2000), Petrick et al. (2010)
and Chien et al. (2011) reported greater affinity of natural fabrics, such as cotton and wool, to
polar nicotine and chemicals in environmental tobacco smoke (ETS) in contrast to polyester.
Similarly, Morrison et al. (2015b) reported the greatest sorption of methamphetamine (a
relatively polar compound) to cotton and a cotton-polyester blend upholstery fabric than
polyester. They speculated that the highest sorption of methamphetamine to the upholstery fabric
was due to the addition of sizing additives, many of which are water-soluble, and are intended to
control the surface properties of textiles. They did not find a difference in sorption between
cotton that was clean versus soiled (presumably with oily compounds). Won et al. (2000, 2001)
reported the affinity of non-polar volatile organic compounds (VOCs) for less polar substrates
such as synthetic fibre carpet and carpet/pad combination than polar gypsum board. Consistent
with these observations, McQueen et al. (2008) commented that the hydrophobic and oleophillic
nature of polyester readily attracted secreted body oils (i.e., compounds responsible for body
odour) and provided a favorable environment for biotransformation and release of the resultant
VOCs in comparison to cotton that sorbed and tended not to release these compounds.
Numerous studies have used chambers to determine the sorption of air-borne chemicals to
materials. Examples of such studies include the sorption of VOCs to indoor materials such as
carpet and gypsum board (Won et al., 2000, 2001), ETS to clothing (Noble, 2000; Chien et al.,
2011), and nicotine to indoor surfaces including fabrics, glass and wood material (Piadé et al.,
1999; Petrick et al., 2010). Conditions such as temperature, air exchange rate and relative
humidity can be controlled and thus investigated in chamber experiments. Recently, Morrison et
al. (2015a) reported fabric-air partition coefficients of phthalates (Diethyl phthalate, DEP and Di-
n-butyl phthalate, DnBP) obtained by exposing the fabrics to phthalate-equilibrated air in a
closed chamber experiment over 10 days. Rauert et al. (2014, 2015) designed a chamber to test
the mechanisms responsible for transferring to dust the flame retardants (FRs) polybrominated
diphenyl ethers (PBDEs) from an electronic casing and hexabromocyclododecane (HBCDD)
from an impregnated curtain. In both studies, they found that abrasion of FR-enriched particles
and fibres from the casing and curtain was likely a more significant pathway with subsequent
deposition to dust.
48
The goal of this study was to investigate the sorption of gas-phase PBDEs to cotton and polyester
fabrics. PBDEs, available as three commercial mixtures differing in bromination, were used as
additive flame retardants in a wide variety of products, including textiles such as curtains and
upholstery fabric (e.g., Abbasi et al., 2015). Although new production of commercial penta- and
octa-BDE mixtures came under national and international control starting in 2003 and deca-BDE
has also been slated for control (UNEP, 2010, 2013; Environment Canada, 2013), PBDEs remain
amongst one of the most prevalent classes of flame retardant found indoors (Bradman et al.,
2014; Abbasi et al., 2016 inter alia). Based on the body of evidence presented above, we
hypothesized that polyester has a higher affinity for non-polar semi-volatile organic compounds
(SVOCs) compared to polar cotton. We designed a chamber study to test this hypothesis using
PBDEs as test chemicals. Cotton and polyester that differed in physical and chemical
characteristics were tested for PBDE sorption as a function of exposure duration, air flow and
temperature. The study used the chamber designed by Rauert et al. (2014). Solid-state 13C
nuclear magnetic resonance (NMR) was also performed to characterize aliphatic versus aromatic
structural moieties in the test fabrics. These structural differences between cotton and polyester
could provide insight into the sorptive behaviour of non-polar PBDEs.
3.2 Experimental method
3.2.1 Test material
Cotton and polyester fabrics (purchased from a local store) were pre-cleaned by pressurized
liquid extraction using Dionex ASE 350 (Thermo Scientific, USA) with hexane (HPLC grade,
Fisher scientific). Pre-cleaned fabrics were wrapped in cleaned aluminium foil and stored at -4ºC
until use. For each experiment, fabrics were cut into 5×5 cm2 squares and weighed before
placement in the test chambers.
3.2.2 Test chambers
A detailed explanation of the test chambers is given by Rauert et al. (2015). Briefly, portable
stainless steel cylindrical chambers of 10 cm diameter and 20 cm height were used at the
University of Birmingham, UK. The total volume of the chamber was 1570 cm3. The lid of the
49
chamber allowed for the inflow and outflow of air using a low volume pump. Two types of
experiments were conducted: without (closed) and with (open) airflow. For the air flow
experiments, a constant air flow of 10 L/min through the chamber (air exchange rate of 6.4
exchanges per minute) was achieved using a Capex L2 Diaphragm Pump (Charles Austin Pumps
Ltd, Surrey, UK). Inflowing air was purified by a polyurethane foam (PUF) disk (140 mm
diameter, 12 mm thickness, 360.6 cm2 surface area, PACS, Leicester, UK) held in a glass
assembly with attachment to the inlet using polypropylene tubing. A similar assembly of two
PUF disks was attached to the outlet to collect PBDEs in outflow air. Only the 'chamber-side'
outlet PUF was treated as a sample as the air-side PUF did not show any breakthrough loss
during experimental design development (Rauert et al., 2015). The length of polypropylene
tubing attached to the outlet was kept at 2 cm to minimize the loss of PBDEs due to sorption to
the tubing surface (Rauert et al., 2015). Two platforms inside the chamber were made of wire
mesh placed on stainless steel O-rings attached within the chambers. The entire chamber
assembly was rinsed once each with hexane, dichloromethane (DCM) and methanol (HPLC
grade, Fisher scientific) before use. The chambers were heated to the desired temperature by
placing them in a hot water bath. A filter paper (47 mm PTFE membrane filter, 1.0 µm pore size,
Whatman, UK) spiked with a known amount of native PBDE standards was placed on the upper
platform in the chamber to act as an emission source (Figure A2.2). One 5×5 cm2 square of pre-
cleaned cotton and a similarly dimensioned square of pre-cleaned polyester fabric were placed
side-by-side at the bottom of the chamber (Figure A2.2).
After completion of each experiment, PUF disks at the outlet, spiked filter paper, and each of the
fabrics squares were collected and stored at -18°C for further laboratory analysis. Internal walls
of the chamber were rinsed three times with hexane and DCM (1:1, v/v) to collect analytes
absorbed onto the walls. The solvent rinse was collected in a glass bottle for further analysis.
Chamber experiments were run without air flow for 24 hours at 40°C and 60°C, whereas
chamber experiments with air flow were conducted for one week at room temperature (~25°C),
and for 72 hours at 40°C and 60°C. Each chamber experiment without air flow was repeated 4
times, whereas 2 replicates were conducted for the experiments with air flow.
50
3.2.3 Extraction and analysis
Full details of extraction and analytical procedures are given in the supplementary information
(SI, Appendix 2). Briefly, each sample was extracted using ASE. The crude extract was then
reduced under gentle stream of nitrogen to 0.5 mL in a Zymark Turbovap (TurboVap II
concentration workstation, Caliper Life Science, Massachusetts, USA) followed by clean-up by
loading onto SPE cartridges filled with 2 g of pre-cleaned alumina and 5 g of pre-cleaned sodium
sulphate (SPE cartridge were self-packed in the laboratory). The analytes were eluted with 30
mL of hexane: DCM (1:1, v/v). The eluate was then reduced to incipient dryness in the Zymark
Turbovap and the dried extract was reconstituted to 100 µL using 13C-BDE-100 (Wellington
laboratories, Guelph, Canada) in methanol as internal standards. The final solution was analysed
for PBDEs on LC-MS/MS using the method described by Rauert et al. (2015) and briefly given
in Appendix 2.
3.2.4 QA/QC
Samples were analysed according to established QA/QC methods. Laboratory blanks were
extracted and analysed with samples from each set of experiment. Samples were spiked with
mass-labeled surrogate standards 13C-BDE-47, -99, -153 and -153 to determine recoveries. A set
of 5 calibration standards with concentrations ranging from 20 to 900 ng/mL were also run
before and after each batch of samples to monitor the sensitivity of the instrument. Average
recoveries of surrogate standards ranged between 77-81%. Blank correction was done using the
criteria explained by Saini et al. (2015). Ninety % of samples had blanks <5% of the sample
concentration and thus did not require correction. Statistical analyses were performed using
Microsoft Office Excel 2007 and STATISTICA software version 8 (StatSoft Inc., Oklahoma,
US), respectively. Non-parametric Mann-Whitney U test (MWU) was performed and used a
significance level of 5%.
3.2.5 Nuclear Magnetic Resonance (NMR) analysis
Solid-state 13C NMR analysis was performed using a Bruker BioSpin Avance III 500MHz NMR
spectrometer fitted with a H-X solid-state NMR probe. Prior to NMR analysis, fabrics were
51
finely ground into a powder using a Wig-L-Bug mechanical grinder. Powdered fabric samples
were packed into a 4mm Zirconium rotor and sealed with a Kel-F cap. Ramped amplitude cross
polarization magic angle spinning (CP-MAS) NMR spectra were acquired with the following
parameters: CP contact time (1ms), MAS spinning speed of 11kHz, and a recycle delay of 1s.
NMR spectra were processed using a zero filling factor of 2 and line broadening of 50Hz. NMR
spectra were phased and baseline corrected using Advanced Chemistry Development (version
15) software.
3.2.6 Scanning Electron microscopic (SEM) images
Scanning electron microscope images of cotton and polyester fabrics were taken at the
University of Toronto using tungsten filament JEOL JSM6610LV microscope operated in
secondary electron imaging mode (JOEL USA, Peabody, MA). Fabric pieces and single fibre
strands were fixed to aluminum stubs using double side carbon (conductive) tape and were
coated with 30 nm thick gold layer using a gold sputter coater (Polaran Range, SC7620, Thermo
VG Microtech UK). Images were captured with 30× and 2,000× magnification at a working
distance of 22 mm using an electron beam high voltage of 15 kV. The fabric weave and surface
structure of single strands of cotton and polyester were captured in images to see the differences
in surface morphology and area.
3.2.7 Density and thickness measurements
Density measurements (mass per unit area) of the fabrics were made using the standard method
CAN/CGSB-4.2 No. 5.1-M90 Unit Mass of Fabrics (CGSB, 2004). The fabrics were conditioned
for minimum of 24 hours at 20°C±1°C and 65%±2% RH (ISO 139: 2005 Textiles - Standard
atmospheres for conditioning and testing). The fabrics were cut into circular pieces of 5 cm
diameter of area 19.635 cm2. Fabric thickness was measured following CAN/CGSB-4.2 No. 37-
2002 Fabric Thickness Method (CGSB, 2002) using 28.66 mm diameter presser foot under an air
pressure of 1.0 kPa. Ten different pieces of each fabric were used as replicates for each
measurement and their averages are reported here.
52
3.2.8 Specific surface area (SSA) measurements
SSA of cotton and polyester fabrics were measured using Brunauer-Emmett-Teller (BET)
adsorption method (Rouquerol et al., 2014). Briefly, fabrics were cut into fine pieces and
samples were kept under vacuum at 60°C for 16 hours to outgas any pre-sorbed chemicals.
Adsorption isotherms were obtained using an Autosorb-iQ gas sorption analyzer (Quantachrome,
Boynton Beach, FL, USA). Adsorbate gas, Krypton (Kr, 99.999%), and purge gas, Helium (He,
99.999%), were purchased from MEGS. Kr sorption isotherms were obtained at 77 K using a
liquid nitrogen (N) bath. Kr was used instead of N to obtain adsorption isotherms as the fabrics’
SSA were < 5 m2/g.
3.3 Results
3.3.1 NMR spectra
The solid-state 13C NMR spectra for polyester and cotton fabrics are shown in Figure 3.1. The
NMR spectrum for polyester showed resonances for reported components within polyester
(Colletti and Mathias, 1988; Gan et al., 2004). Resonances at 36-44 ppm (labelled as ‘a’) and 62-
72 ppm (labelled as ‘b’) are consistent with mid-chain CH2 and CH2 next to carboxylic groups
respectively. The aromatic (labelled as ‘c’) and carboxylic (labelled as ‘d’) carbon were also
observed in the spectrum for polyester. Overall, the solid-state NMR spectrum revealed the
aromatic-rich nature of the polyester fabric used in this study, which is consistent with a
terephthalate monomer. The NMR spectrum of the cotton reflected its cellulose-rich nature
(Horii et al., 1987; Castelvetro et al., 2007). Hexose ring carbons were visible at 62–70 ppm and
72–90 ppm (labelled as ‘e’ and ‘f’) and the anomeric carbon was observed at 104–110 ppm.
Sorbent characteristics such as polarity and aromaticity have been correlated to different sorption
behaviour (Gustafsson et al., 1997; Bucheli and Gustafsson, 2000; Accardi-Dey and Gschwend,
2002; Salloum et al., 2002; Chen et al., 2005). It is inferred based on these spectra that polyester
would sorb more PBDEs under equilibrium conditions due to the high aromaticity compared to
cotton, if the physical characteristics such as densities of fabrics are similar.
53
Figure 3.1. Solid-state 13C NMR spectra of polyester and cotton. Chemical shift assignments correspond to: a) mid-chain CH2 groups, b) CH2 groups adjacent to COOH groups, c) aromatic carbon, d) carboxylic carbon, e) hexose ring carbons in cellulose, f) hexose ring carbons in cellulose closer to O, and g) anomeric carbon in cellulose.
3.3.2 SEM images, density and specific surface area
Cotton and polyester fabric samples differed in weaving pattern and surface morphology under
30× and 2000× magnification (Figure 3.2). Cotton had a dense weave whereas polyester was less
dense. Single strands of cotton under 2000× magnification showed a convoluted structure with
grooves and folds on its surface consistent with its natural origin (Mather and Wardman, 2011).
In comparison, polyester had a smooth surface consistent with its synthetic origin and spinning
(Mather and Wardman, 2011). The average areal densities of cotton and polyester samples
measured at 20°C±1°C and 65%±2% RH were 164±1.3 and 45±0.6 g/m2, respectively. Average
thickness of the samples of cotton and polyester were 0.05±0.002 and 0.02 cm, respectively.
Thus, volumetric densities were 310,510±12720 and 253,390±3460 g/m3 for cotton and
polyester, respectively. BET-SSA of cotton and polyester were 0.72 (0.07 < P/P0 < 0.18, C =
7.2) and 0.07 (0.13 < P/P0 < 0.21, C = 2.0) m2/g, respectively. Ten times higher BET-SSA of
cotton than polyester is consistent with differences seen in the SEM images (Figure 3.2).
AMAN SOLID STATE NMR COTTON.ESP
200 180 160 140 120 100 80 60 40 20 0Chemical Shift (ppm)
Polyester
Cotton
a
b
c
d
e
f
g
54
Figure 3.2. SEM images of cotton and polyester fabrics (top) under 30× magnification and single strand structure (bottom) under 2000× magnification.
3.3.3 Recoveries of PBDEs from chambers
Total recoveries of Σ7PBDEs from all chamber compartments (e.g., filter paper, fabrics, chamber
wall rinses and outflow PUF) ranged between 64–91% and 60–100% for chambers without and
with air flow, respectively (Figure A2.3). Recoveries tended to be lowest at 60°C, particularly
with air flow (although not statistically significant), which is consistent with greater chemical
loss from the filter paper and significantly higher outflow air concentrations (Σ7PBDEs: 174
ng/PUF) compared to that at room temperature and 40°C (Σ7PBDEs: 38–40 ng/PUF) (MWU,
p<0.05; Figure A2.5). Less than 100% recoveries were found for most analytes which could be
due to: (i) analytical uncertainties, (ii) sink effects of the chamber that were not captured by the
chamber wall rinses, and (iii) unaccounted loss of analytes to air while opening the chamber for
sample collection.
Chambers without air flow: The mass of spiked PBDEs that remained on the filter paper (FP)
was statistically indistinguishable at 40°C and 60°C. Total remaining mass on the filter paper
ranged between 173–179 ng/FP and increased with decreasing congener vapour pressure from 4–
20% remaining of BDE-47,-85, -99 and -100 compared to 38% of BDE-153, 25% of -154, and
55
71-74% of -183 (Figure A2.4). The percentage distribution and total mass sorbed to chamber
walls was also statistically indistinguishable at 40°C (Σ7PBDEs 243 ng) and 60°C (Σ7PBDEs 325
ng). Similarly, mass sorbed to both fabrics was statistically indistinguishable at 40°C versus
60°C with Σ7PBDEs ranging between 25–33 ng/fabric square.
Chambers with air flow: Total mass remaining on the filter paper at 60°C (Σ7PBDEs 72 ng/FP)
was significantly less (MWU, p<0.05) than that at 40°C (Σ7PBDEs 332 and 335 ng/FP,
respectively), indicating more volatilization at 60°C (Figure A2.5). In terms of percentages, 4–
84% remained on the filter paper at room temperature and 40°C compared to 1–48% at 60°C.
Mass sorbed to chamber walls was statistically indistinguishable at room temperature, 40°C and
60°C with Σ7PBDEs ranging between 227–272 ng. Mass sorbed to cotton was statistically
indistinguishable at room temperature, 40°C and 60°C with Σ7PBDEs ranging between 15–19
ng/fabric square, whereas mass sorbed to polyester at 40°C (Σ7PBDEs 9 ng/square) was
statistically less than at room temperature and 60°C (Σ7PBDEs 15 and 20 ng/square,
respectively), recalling that the experiment at room temperature was of 1 week duration versus
72 hours for the 40°C and 60°C experiments (MWU, p<0.05).
On an area basis, the chamber walls sorbed more PBDEs than fabric due to the large internal
surface area of 785 cm2 compared to 25 cm2 fabric squares (Figure A2.6). However, fabrics had
comparable or up to 5 times greater sorption than the chamber walls when normalized per planar
surface area (Figure A2.6). The wall sink effect has been discussed in numerous chamber studies
as an unavoidable feature of such studies (e.g., Uhde and Salthammer, 2006; Katsumata et al.,
2008; Rauert et al., 2014, 2015).
3.3.4 Sorption of PBDEs to cotton and polyester
Chambers without air flow: At 40°C and 60°C after 24 hours, cotton and polyester had
statistically similar concentrations of Σ7PBDEs ranging between 1–1.3 ng/cm2 (planar surface
area) with maximum sorption of BDE-47 ranging between 0.5–0.6 ng/cm2 (MWU, p>0.05)
(Figure 3.3). However at 40°C and 60°C, Σ7PBDEs were 0.35 and 0.36 ng/cm2-BET sorbed to
polyester compared to 0.007 and 0.009 ng/cm2-BET sorbed to cotton, respectively (MWU,
p<0.01) (Figure 3.4). The difference between cotton and polyester of 40–50 times of greater
56
sorption normalized to BET-SSA versus planar surface area is far greater than the 10 times
higher BET-SSA of cotton than polyester.
Figure 3.3. PBDEs sorbed to cotton and polyester expressed per cm2 planar surface area in chambers without air flow at 40°C and 60°C after 24 hours (error bars show maximum and minimum concentration).
Figure 3.4. PBDEs sorbed to cotton and polyester expressed per cm2 BET-SSA in chambers without air flow at 40°C and 60°C after 24 hours (error bars show maximum and minimum concentration). Note: Y-axis is a log scale.
0
0.2
0.4
0.6
0.8
1
1.2
ng/c
m2 o
f fab
ric
Cotton Polyester
0.00001
0.0001
0.001
0.01
0.1
1
ng/c
m2 B
ET-
SSA
of f
abri
c
Cotton Polyester
60°C; 24 hours 40°C; 24 hours
60°C; 24 hours
40°C; 24 hours
57
Figure 3.5. PBDEs sorbed to cotton and polyester expressed per gram of fabric in chambers without air flow at 40°C and 60°C after 24 hours (error bars show maximum and minimum concentration).
With 3.6 times lower density of polyester than cotton, polyester had 3–10 times higher
concentrations of PBDEs when expressed per unit mass of fabric, i.e., Σ7PBDEs concentrations
of 247 and 255 ng/g for polyester compared to 50 and 66 ng/g for cotton at 40°C and 60°C,
respectively (MWU, p<0.05; Figure 3.5). Thus, at both temperatures we observed no differences
among PBDE concentrations between polyester and cotton when normalized to per unit planar
surface area, but 40–50 times greater sorption when normalized to BET-SSA, and 3–10 times for
when normalized to mass (MWU, p<0.05). The higher sorption of PBDEs to polyester than
cotton when considering BET-SSA and fabric mass suggest either a higher affinity of PBDEs for
polyester than cotton, presumably due to both being non-polar and the high aromaticity of
polyester, or that PBDEs were ‘diluted’ by the large surface area of cotton relative to polyester.
We note that the difference in sorption per unit BET-SSA (40-50 times) was greater than the
surface area difference (10 times) between the fabrics.
0
50
100
150
200
250
300 ng
/g o
f fab
ric
Cotton Polyester
60°C; 24 hours 40°C; 24 hours
58
Figure 3.6. PBDEs sorbed to cotton and polyester per cm2 planar surface area of fabric in experiments with air flow (error bars show maximum and minimum concentration).
Figure 3.7. PBDEs sorbed to cotton and polyester expressed per cm2 BET-SSA of fabric in chambers with air flow (error bars show maximum and minimum concentration). Note: Y-axis is a log scale.
Chambers with air flow: Similarly to experiments without air flow, cotton and polyester had
statistically similar PBDE mass sorbed per unit planar surface area at room temperature, 40°C
and 60°C (MWU, p>0.05) (Figure 3.6). Σ7PBDE concentrations ranged from 0.6–0.8 and 0.4–0.8
ng/cm2 for cotton and polyester, respectively. Again, significantly more PBDEs were sorbed per
unit BET-SSA of polyester (Σ7PBDEs 0.1–2.4 ng/cm2-BET) than cotton (Σ7PBDEs ~0.005
0
0.1
0.2
0.3
0.4
0.5 ng
/ cm
2 of
fabr
ic
Cotton Polyester
0.00001
0.0001
0.001
0.01
0.1
1
ng/c
m2 B
ET-
SSA
of f
abri
c Cotton Polyester
Room temp; 1 week 40°C; 72 hours 60°C; 72 hours
Room temp; 1 week
40°C; 72 hours
60°C; 72 hours
59
ng/cm2-BET) with the difference of 20–50 times being comparable to that under closed
conditions (MWU, p<0.01) and this differences is much greater than the 10–fold difference in
BET–SSA (Figure 3.7). Similarly, PBDEs sorbed per unit mass of polyester (Σ7PBDEs 70–170
ng/g) was significantly greater than cotton (Σ7PBDEs 36–40 ng/g; MWU, p<0.05) (Figure 3.8).
In summary, PBDE concentrations did not differ between polyester and cotton when normalized
to planar surface area, but polyester concentrations were 20–50 times greater when normalized to
BET-SSA, and 2–4 times greater when normalized to mass (MWU p<0.05).
Figure 3.8. PBDEs sorbed to cotton and polyester per gram of fabric in experiments with air flow (error bars show maximum and minimum concentration).
3.3.5 Distribution coefficient, K’D (Cfabric (or steel)/Cchamber air)
In the experiments with air flow, chamber air concentrations were calculated from the PBDE
mass sorbed to PUF at the chamber exit and air flow rate (10 L/min) (Table 3.1). Distribution
coefficients, K’D (area normalized, unit of m) were calculated as ratios of mass sorbed to fabrics
or steel of the chamber walls (pg/m2, planar surface area of fabrics) and corresponding air
concentrations (pg/m3). Since time to reach equilibrium for fabrics was estimated as >10 years
based on cotton-air equilibrium partition coefficients estimated with COSMO-RS solvation
theory under typical indoor conditions (Saini et al., Ch 4), it is highly unlikely that PBDEs had
attained equilibrium in the chambers with exposure times of 72 hours to one week. Thus, we use
0
20
40
60
80
100
ng/g
of f
abri
c
Cotton Polyester
Room temp; 1 week 40°C; 72 hours 60°C; 72 hours
60
the term distribution coefficient rather than partition coefficient to denote that the system was not
at equilibrium.
Table 3.1. Average measured chamber air concentrations and planar area-normalized distribution coefficients (pg/m2 fabric or chamber to pg/m3 air concentration; K’cotton-air, K’polyester-air, and K’steel-air m) at room temperature (one week), and 40°C and 60°C (72 hours).
BDE-47 BDE-85 BDE-99 BDE-100 BDE-153 BDE-154 BDE-183 Chamber air concentrations (pg/m3) Room temp. (~25°C) 210 16 59 84 9.9 19 2.7 40°C 422 57 126 199 24 51 12 60°C 1107 438 699 896 297 546 57
K’cotton-air (m) Room temp. (~25°C) 1.3 × 104 2.9 × 104 1.7 × 104 2.0 × 104 1.5 × 104 1.7 × 104 2.2 × 104 40°C 6.2 × 103 7.5 × 103 5.6 × 103 5.5 × 103 1.4 × 104 8.0 × 103 3.4 × 104 60°C 1.7 × 103 2.0 × 103 1.9 × 103 1.8 × 103 2.1 × 103 1.8 × 103 4.7 × 103
K’polyester-air (m) Room temp. (~25°C) 1.6 × 104 4.8 × 104 2.1 × 104 2.3 × 104 2.3 × 104 2.5 × 104 6.4 × 104 40°C 2.6 × 103 7.2 × 103 4.0 × 103 2.6 × 103 1.3 × 104 6.5 × 103 3.1 × 104 60°C 1.1 × 103 2.5 × 103 1.4 × 103 8.8 × 102 2.9 × 103 1.1 × 103 1.0 × 104
K’steel (m) Room temp. (~25°C) 2.5 × 103 2.5 × 104 9.8 × 103 8.7 × 103 2.2 × 104 1.8 × 104 2.8 × 104 40°C 1.3 × 103 8.9 × 103 5.3 × 103 3.7 × 103 1.5 × 104 1.0 × 104 8.1 × 103 60°C 3.0 × 102 1.3 × 103 8.8 × 102 6.2 × 102 1.7 × 103 1.1 × 103 4.7 × 103
PBDE air concentrations were 5–30 times higher at 60°C than at room temperature, consistent
with tendency to partition more into gas phase than the condensed phases at higher temperatures.
Similar findings were reported by Clausen et al. (2012), with up to 211-fold increase in gas-
phase concentration of di-(2-ethylhexyl) phthalate (DEHP) emitted from a vinyl flooring test
piece kept in a chamber with a 38°C increase in chamber’s temperature at steady state. As
expected, BDE-47, -99 and -100 had consistently higher air concentrations than other PBDEs at
every temperature. This explains the inverse relationship between PBDE sorbed to cotton,
polyester and steel versus octanol-air partition coefficient, KOA, and the positive relationship with
vapour pressure (Figure A2.7).
K’D values normalized to planar surface area for cotton, polyester and steel were comparable for
each congener (Table 3.1). K’D values for polyester were 14–104 times higher than those for
61
cotton (MWU, p<0.01) when normalized to BET-SSA (BET-SSA was not available for steel,
Table A2.3).
Log K’D values for all materials increased with log KOA and decreased with vapour pressure
(Figure A2.8). K’steel-air showed the strongest relationship whereas K’cotton-air showed the weakest
relationship that was not significant. We attribute the latter to less uniformity in physical
structure amongst samples of cotton than polyester, which in turn is less uniform than the steel
chamber walls.
3.4 Discussion
These results confirm that cotton and polyester fabrics sorb gas-phase PBDEs from surrounding
air, with an area normalized distribution coefficients, K’D, of ~103 to 104 m after one week at
room temperature. These K’D values imply that 1 m2 of these fabrics would sorb PBDEs present
in 103 to 104 m3 of equivalent air volume under the given conditions. Similar K’D for cotton and
polyester fabrics indicates air side controlled uptake of PBDEs under kinetic or non-equilibrium
conditions. Kinetic phase of uptake is relevant for “real life” scenarios where it is highly unlikely
that equilibrium will be reached between fabrics and air, given the expected high sorptive
capacity of fabrics.
On a planar surface area basis, cotton and polyester had statistically similar sorption of PBDEs.
However, polyester showed 3–10 times greater sorption when expressed per gram of fabric
relative to planar surface area and 20–50 times greater than cotton when the BET–SSA was
considered, which could have two explanations. First, the large BET-SSA of cotton could have
‘diluted’ sorbed PBDEs. If this is the case, then further testing is necessary to determine if cotton
ultimately achieves similar sorption as polyester, given sufficient time for the chemical to
penetrate the interstices of cotton. Alternatively or in addition, polyester could have sorbed more
than cotton because of chemical compatibility between the non-polar PBDEs and the polyester
sorbent (e.g., Won et al., 2000, 2001). This explanation is consistent with the sorption difference
being greater than the difference in BET-SSA between the two fabrics. The importance of
considering BET-SSA is that it indicates the potential of cotton to remain in kinetic uptake stage
for longer compared to polyester due to more binding sites. Due to difference in physical
62
morphology and chemical structure, McQueen et al. (2008) also suggested the greater
availability of binding sites in cotton for body oils than polyester, which resulted in less
bioavailability of those compounds for microbial degradation into odour-producing compounds.
Analogously, we hypothesize that greater sorption of SVOCs by cotton than polyester could lead
to less availability for dermal uptake.
Solid-state 13C NMR analysis confirmed that the polyester fabric exhibited high aromaticity
whereas cotton was dominated by cellulose. Abundance of non-polar moieties is expected to
favour sorption of non-polar organic compounds. Cellulose has been shown to be a poor sorbent
for a range of non-polar compounds due to the lack of aromaticity and polar nature (Xing et al.,
1994a, 1994b, 1994c; Salloum et al., 2002). Wang and Xing (2007) also showed that charring
resulted in enhanced aromaticity of cellulose along with increased surface area and porosity,
hence increased the sorption of phenanthrene and naphthalene. Therefore, sorption can also be
driven by physical characteristics such as surface area and porosity of sorbent apart from
chemical characteristics (Wang and Xing, 2007).
If we assume the chamber as an indoor mesocosm, with the chamber walls mimicking indoor
surfaces, these results show that fabrics (e.g., clothing, upholstery) with their large surface area,
will act as a substantial sink for these chemicals under ambient conditions. The chamber
experiments were conducted for a short duration. In reality, the time available for chemical
sorption is much greater, particularly if the chemical is not lost during laundering (Schreder and
La Guardia, 2014, Saini et al., Ch 5).
These results are also significant for human exposure, since dermal uptake of flame retardants
has been shown to occur (Abdallah et al., 2015, 2016). Sorption and distribution coefficients
estimated at room temperature are relevant for chemical uptake from air to the air-side of fabrics
whereas the data for 40°C could be relevant for the skin-side of fabrics worn as clothing. These
results suggest greater sorption from air due to cooler ambient temperatures; whether the sorbed
chemicals are released to the fabric-skin air space at a higher skin temperature (as the distribution
coefficient decreases) remains to be tested.
63
3.5 Conclusions
Chamber studies conducted to test the sorption of a range of gas-phase PBDE congeners to
cotton and polyester showed that 1 m2 of these fabrics can sorb PBDEs present in 103 to 104 m3
of equivalent air volume after one week at room temperature under conditions with air flow. As
expected, the distribution coefficients were proportional to KOA and inversely related to vapour
pressure. The hypothesis that polyester sorbed more PBDEs than cotton was not supported when
considering planar surface area. However, polyester sorbed 3–10 times more than cotton per
gram of fabric and 20–50 times more when considering BET surface area. Greater sorption of
PBDEs by polyester than cotton could be explained by ‘dilution’ due to the large surface area of
cotton or the greater affinity of polyester for non-polar PBDEs. The former is consistent with
data presented here which showed a greater difference in sorption between the fabrics than the
difference in BET-SSA itself, but latter is expected on the basis of NMR analysis and reports
from the literature. We hypothesize that lower PBDE concentrations in cotton than polyester on a
BET surface area basis could reduce the potential for dermal transfer. The results also raise the
question of whether fabrics that sorb relatively more chemical from air at cooler ambient
temperatures could subsequently release them to the fabric-skin space at relatively higher skin
temperatures. Finally, the results point to the importance of fabrics (e.g., clothing, draperies, and
upholstery) as a sink for PBDEs and other non-polar compounds emitted to the indoor
environment.
Acknowledgements
We thank Dr. Ronald Soong (University of Toronto Scarborough, Canada) for acquiring NMR
spectra on the fabric samples, Dr. Rachel McQueen, University of Alberta, Canada, for fabric
density and thickness measurements, and Prof. Nathalie Tufenkji (McGill University, Canada),
particularly David Morris, for BET measurements. Assistance from Prof. Stuart Harrad’s group
(University of Birmingham, UK) is also appreciated. Research funding to AS was provided by
European Union Seventh Framework Program (FP7/2007-2013) under Grant Agreement No.
295138 (INTERFLAME project) and the Natural Sciences and Engineering Research Council of
Canada (NSERC).
64
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Chapter 4: Characterizing the accumulation of semi-volatile
organic compounds to fabrics in indoor environments
4.1 Introduction
Clothing plays an influential role in human exposure to chemicals. Protective clothing is used in
occupational and non-occupational settings to minimize chemical exposure by minimizing skin
contact of gas- and particle-phase chemicals (e.g., Machera et al., 2009; Fenske et al., 2012;
Macfarlane et al., 2013; Moore et al., 2014). Conversely, clothing can be a source of exposure to
chemicals as fabrics can release chemicals sorbed intentionally and unintentionally (e.g., Blum et
al., 1978; Horstmann and McLachlan, 1994; Klasmeier et al., 1999; Curwin et al., 2005).
Recently, Morrison et al. (2015b) investigated the accumulation of gas-phase methamphetamine
on cotton and polyester clothing, upholstery and toy fabrics. They estimated that a toddler
mouthing upholstery fabric, which had the highest fabric-air partition coefficient of the fabrics
tested, could exceed the therapeutic dose for methamphetamine in a scenario of 1 ppb
methamphetamine in indoor air and a 60 days uptake period.
Morrison et al. (2016) also addressed the possibilities of clothing accelerating or impeding
dermal exposure in human trials by investigating cotton clothing that was clean and clothing
exposed to diethyl phthalate (DEP) and di-n-butyl phthalate (DnBP). When compared to
exposure trials that isolated dermal uptake via bare skin (Weschler et al., 2015), Morrison et al.
(2016) showed that wearing clean cotton clothes acted as a barrier to reduce the dermal uptake of
DEP and DnBP but dermal uptake was enhanced by wearing clothing exposed to these
chemicals.
Several studies have investigated uptake and loss between fabrics and chemicals in ambient
indoor air such as Environmental Tobacco Smoke (ETS), nicotine and moth repellents (e.g., De
Coensel et al., 2008; Feldman, 2010; Chien et al., 2011). One hypothesis that has been proposed
is that sorption of polar chemicals such as nicotine, is related to a fabric’s hygroscopicity or
‘moisture regain’ (percent weight gain of a bone dry fibre exposed to air under standard
temperature and moisture) (Piadé et al., 1999; Noble, 2000; Petrick et al., 2010). Fabrics of
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natural origin (wool, cotton and linen) with the greatest hygroscopicity, showed the greatest
sorption of polar chemicals. In comparison, Won et al. (2000, 2001) found that low polarity
VOCs preferentially sorbed to non-polar indoor materials such as carpeting with olefin fibres,
and vice versa. Saini et al. (Ch 3) found that gas-phase non-polar polybrominated diphenyl ethers
(PBDEs) sorption was similar to cotton and polyester when expressed on a planar surface area
basis, but polyester sorbed more when specific surface area was considered. These results
suggested that either cotton ‘diluted’ the PBDEs or that polyester showed a greater capacity for
these non-polar chemicals. The latter hypothesis is in line with findings in the literature but less
likely under non-equilibrium conditions due to air-side controlled uptake.
In addition to the influence of chemical properties of the sorbing chemical and fabric, the
physical properties of the fabric can also influence sorption. For example, natural fibres such as
cotton (cellulose) and wool (protein) tend to have large and irregular surface areas and a porous
structure that favour sorption and entrapment of particles compared to synthetically derived and
spun fabrics such as polyester and rayon (rayon is synthetically spun cellulose) (Cieślak, 2006;
Petrick et al., 2010 inter alia).
Quantifying partition coefficients for a sorbing chemical between fabric sorbent and air is a
common method of investigating sorption behaviour. Won et al. (2000) found that equilibrium
partition coefficients of volatile organic compounds (VOCs) for synthetic carpet were inversely
related to the vapour pressures of those chemicals. For semi-volatile organic compounds
(SVOCs), fabric-air partition coefficients, Kfabric-air, of ~105 to 106 (v/v) have been reported for
selected phthalates and cotton and polyester (Bi et al., 2015; Morrison et al., 2015a) after 20-60
days exposures. Values of Kfabric-air were greater for higher molecular weight phthalates as
expected based on their vapour pressures. Morrison et al. (2015b) measured Kfabric-air for polar
methamphetamine and a variety of sorbents, such as a polyester shirt, a cotton shirt and a
polyester/cotton blend upholstery fabric. The upholstery fabric had highest Kfabric-air, which
increased as a function of relative humidity (RH), that they attributed to the addition of ‘sizing’
additives comprised of water-soluble filler agents (Morrison et al., 2015b). This explanation is
consistent with the hypothesis that sorption of polar chemicals can be related to the
hygroscopicity of a fabric (Noble, 2000; Petrick et al., 2010). Morrison et al. (2015b) did not
observe differences in Kfabric-air between methamphetamine sorbed to a clean versus skin oil-
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soiled cotton shirt, indicating that increasing the hydrophobicity of the cotton did not alter the
sorption of this polar chemical. Saini et al. (Ch 3) reported distribution coefficients between
cotton, polyester and gas-phase PBDEs that were positively related to the octanol-air partition
coefficient KOA. Distribution coefficients of 103 to 104 m (mass/surface area to mass/air volume)
at room temperature after 1 week exposure confirmed the high sorptive capacity of both fabrics.
No studies were found that investigated the sorption of a range of SVOCs to fabrics nor that
characterized uptake kinetics of SVOCs.
In this study, we investigated the accumulation to cotton and rayon of two groups of SVOCs
commonly measured in indoor air, phthalates and halogenated flame retardants (HFRs). Cotton,
which is second in demand of all fabrics worldwide (Carmichael, 2015), is a natural fabric
consisting of 88-96% cellulose in raw fibres (Mather and Wardman, 2011). Rayon is a semi-
synthetic fabric that also consists of cellulose but the fibres are artificially spun (Shaikh et al.,
2012). Phthalates are widely used as plasticizers and/or to hold scent in a range of consumer
products including cosmetics/personal care products and indoor materials such as vinyl flooring
(Schettler, 2006; Koniecki et al., 2011; Romero-Franco et al., 2011; Kim et al., 2013). HFRs
(polybrominated diphenyl ethers or PBDEs and “novel” flame-retardants or NFRs) are used as
additive flame retardants in plastic polymers of electronics, polyurethane foam used in
upholstered furniture, carpets and insulation material, to comply by flammability standards
(BEARHFTI, 2015). We did not consider chemicals such as nonylphenol ethoxylates (NPEs) or
perflourinated compound that are intentionally added to clothing for purposes such as fabric
printing and to confer water repellent qualities (Herzke et al., 2012; Brigden et al., 2014)
4.2 Experimental method
4.2.1 Test materials
Cotton and rayon fabrics were purchased from a local fabric store. Squares of 35×35 cm2 were
pre-cleaned by pressurized liquid extraction using Dionex ASE 350 (Thermo Scientific, USA)
with hexane (HPLC grade, Fisher scientific). Cleaned fabric squares were dried in a desiccator
and fixed to square metal frames for deployment.
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4.2.2 Home and office deployment
Cotton and rayon fabric squares were deployed for 28 days in 17 bedrooms and 14 living rooms
located in 20 homes plus five offices in the Greater Toronto Area, Canada, during summer 2013.
The ages of the buildings ranged from 1 to 120 years. Indoor temperatures ranged between 20°-
35°C. Fabric squares were hung 1 m above ground on a metal stand. The University of Toronto
Ethics board approved all aspects of this study and all participants provided consent prior to
sample deployment in their homes and offices.
4.2.3 Chemical uptake study
To obtain temporal uptake profiles for phthalates and HFRs, cotton and rayon squares (35×35
cm2) were deployed in an office at University of Toronto for 56 days. Fourteen squares each of
cotton and rayon were hung 1.5 m above ground. One square of each of cotton and rayon was
collected weekly and in addition, one duplicate square was collected on days 7, 28 and 56 after
deployment. Duplicates collected on day 7 were composited to increase analytical detection
whereas duplicates collected on days 28 and 49 were extracted and analysed separately to
monitor the repeatability of results.
Corresponding air concentrations were measured continuously throughout the sampling period
using a low volume active air sampler (LV-AAS; BGI 400S, Pacwill environmental, Canada) at
a flow rate of 10L/min. Gas- and particle-phase chemicals were collected on a PUF-XAD
sampling train and a glass fibre filter, respectively. Air samples were collected at weekly
intervals along with fabric squares. Further details on active air sampling are given by Saini et al.
(2015).
4.2.4 Extraction and analysis
Fabric squares, PUF plugs, XAD resin and filters were extracted using ASE 350. An in-cell
extraction and clean-up method was used as explained by Saini et al. (2015). Hexane was used
for fabric squares, whereas hexane and dichloromethane (DCM, HPLC grade, Fisher Scientific)
(1:1, v/v) were used to extract active air samples. Extracts were then reduced to 0.1 mL under a
gentle stream of nitrogen in a Zymark Turbo-vap (TurboVap II concentration workstation,
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Caliper Life Science, Massachusetts, USA) followed by reconstituting the final volume to 0.5 ml
in GC vials using isooctane (HPLC grade, Fisher scientific). Six phthalates (DEP, DnBP, DiBP,
BzBP, DEHP, DiNP), 14 PBDE congeners spanning from tri- to deca-BDE, and 10 NFRs (ATE,
PBBz, HBB, PBT, EH-TBB, BEH-TEBP, s-DP, a-DP, OBIND, DBDPE) (see Table A3.1 for
full details) were analysed using Agilent 6890N gas chromatograph with a DB-5MS column (30
m for phthalates, 15 m for HFRs) coupled to an Agilent 5975 inert mass-spectrometer (GC-MS)
run in electron ionization (EI) and negative chemical ionization (NCI) modes for phthalates and
HFRs, respectively. Full details are provided by Saini et al. (2015).
4.2.5 QA/QC
Blanks and recoveries were monitored to assess quality assurance/quality control (QA/QC)
throughout the sampling campaign and analytical measurements. Recoveries of phthalates and
HFRs were monitored by adding surrogate standards to each sample before extraction. Surrogate
standards were DEP-d4 for phthalates and mPBBz, mHBB (mass-labelled NFRs) and F-BDE-
100, -154, -208 (fluorinated BDEs) for HFRs (Accustandard, USA and Wellington laboratories,
Canada). The average recovery of surrogate standards was 50% for DEP-d4 and 80-104% for
four HFR surrogates with the exception of F-BDE 208 which was, on average, 60%. Our
subsequent work showed recoveries of ≥ 80% for higher molecular weight phthalate surrogates.
Data were not recovery corrected. The data were quantified using an internal standard
Fluoranthene-d10 and BDE-118 for phthalates and HFRs, respectively, which were added to
final volume of the extract before injecting on the GC. Quantitation was done using 6-point
calibration curve for GC-MS/EI analysis of phthalates and 5-point calibration curve for GC-
MS/NCI analysis of HFRs. Laboratory and field blanks were extracted and analysed (spiked with
surrogate and internal standards) in every batch of 10 samples. All results were blank corrected
according to the criteria explained by Saini et al. (2015). BDE-209 data from offices was
discarded due to contamination during laboratory analysis. Analytical methods for phthalates and
HFRs were validated for their reproducibility using standard reference material (NIST SRM-
2585) and/or spiked samples (Saini et al., 2015).
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4.2.6 Data analysis
Descriptive data analyses and generation of graphs were done using Microsoft Office Excel
2007. All statistical tests were performed with STATISTICA software version 8 (StatSoft Inc.,
Oklahoma, US). Non-parametric test procedures (Mann-Whitney U test, MWU and Kruskal-
Wallis ANOVA, KWA) were employed for inter-group comparison at a significance level of 5%.
4.2.7 Scanning electron microscopic (SEM) images
The fabric weave and surface structure of single strands of cotton and polyester were captured in
images to assess the differences in surface morphology and area. Scanning electron microscopic
images of the cotton and rayon fabrics deployed indoors were taken using a tungsten filament
JEOL JSM6610LV microscope operated in secondary electron imaging mode (JOEL USA,
Peabody, MA). Pieces of fabric and single fibre strands were fixed to aluminum stubs using
double-sided carbon (conductive) tape and were coated with a 30 nm thick gold layer using a
gold sputter coater (Polaran Range, SC7620, Thermo VG Microtech UK) to enhance the ability
of the samples to produce sufficient secondary electrons to create images. Photographic images
were captured with 30× and 2,000× magnification at a working distance of 22 mm using an
electron beam high voltage of 15 kV.
4.2.8 Density and thickness measurements
Density measurements (mass per unit area) of the fabrics were made using the standard method
CAN/CGSB-4.2 No. 5.1-M90 Unit Mass of Fabrics (CGSB, 2004). The fabrics samples were
conditioned for minimum of 24 hours at 20°C±1°C and 65%±2% RH (ISO 139: 2005 Textiles -
Standard atmospheres for conditioning and testing). Ten replicate measurements of the thickness
of the fabrics was made on circular pieces of 5 cm diameter, having an area of 19.6 cm2
following CAN/CGSB-4.2 No. 37-2002 Fabric Thickness Method using 28.7 mm diameter
presser foot under pressure of 1.0 kPa.
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4.3 Results
4.3.1 Physical features
Both cotton and rayon samples had dense weaves as seen at 30× magnification (Figure A3.1,
top). Single strands of cotton at 2000× magnification (Figure A3.1, bottom) showed a convoluted
structure with grooves and folds on the surface, consistent with its natural origin (Mather and
Wardman, 2011). In comparison, single strands of rayon were smooth and even with less surface
area than cotton. The diameter of single strands of cotton and rayon were similar at ~20 µm.
Specific surface areas (SSA) of cotton and rayon measured using Brunauer-Emmett-Teller or
BET adsorption method were 0.72 and 0.18 m2/g BET-SSA, respectively. The average densities
of cotton and rayon samples were of 164±1.3 and 183±4.3 g/m2, respectively. The average
thicknesses of cotton and rayon samples were also similar at 0.50±0.02 and 0.47±0.01 mm,
respectively.
4.3.2 SVOC accumulation to fabrics from indoor air
Phthalates and HFRs were detected in all fabric samples after 28 days of deployment (Tables
A3.3 and A3.4; Figures A3.2 and A3.3). ∑6Phthalate (geomean) concentrations were two to three
orders of magnitude higher than ∑14PBDEs, which were 2 to 13 times higher than ∑10NFRs
(Figure 4.1). These differences are consistent with differences found with respect to indoor air
concentrations (Rudel et al., 2003, 2010; Saini et al., 2015). Cotton and rayon accumulated
statistically indistinguishable concentrations of ∑6phthalates and ∑14PBDEs (MWU, p>0.05)
when expressed on a planar surface area basis. ∑10NFRs concentrations were significantly higher
for rayon than cotton in homes as well as in offices (MWU, p<0.05) (Figure 4.1c), which we
attribute to low concentrations and hence greater analytical uncertainty.
∑6Phthalate concentrations in cotton and rayon ranged from 130–1584 ng/dm2 of fabrics with no
significant difference among bedrooms, living rooms or offices (KWA, p>0.05). Concentrations
of individual phthalates (geomean) accumulated by cotton varied from 2.3 (BzBP) to 60 ng/dm2
(DnBP) in homes and 18 (BzBP) to 445 ng/dm2 (DnBP) in offices. In comparison, rayon
concentrations ranged between 1.3 (BzBP) to 56 ng/dm2 (DEP) in homes and
74
Figure 4.1. Accumulation of phthalates (a), PBDEs (b), and NFRs (c) to cotton and rayon fabrics as percentage contribution of each chemical (left Y-axis) and total concentration (right Y-axis) expressed as median (triangle) and geometric mean (circle). Concentrations expressed according to planar surface area. Error bars represent 1st and 3rd quartiles.
0
1000
2000
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0%
20%
40%
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∑ P
htha
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s ng/
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% c
ontr
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of
phth
alat
es/d
m2 fa
bric
DEP DiBP DnBP BzBP DEHP DiNP ∑Phthalates median ∑Phthalates GM (a)
0
10
20
30
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0%
20%
40%
60%
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∑ B
DE
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% c
ontr
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of B
DE
/dm
2 fa
bric
BDE-17 BDE-28 BDE-71 BDE-47 BDE-66 BDE-100 BDE-99 BDE-85 BDE-154 BDE-153 BDE-138 BDE-183 BDE-190 BDE-209 ∑BDEs GM ∑BDEs Median
(b)
0
1
2
3
4
5
0%
20%
40%
60%
80%
100%
Cotton Rayon Cotton Rayon Cotton Rayon
Livingroom (n=14) Bedroom (n=17) Office(n=5)
∑N
FR n
g/dm
2
% c
ontr
ibut
ion
of N
FR/d
m2
fabr
ic
ATE PBBz PBT HBB EH-TBB BEH-TEBP s-DP a-DP OBIND DBDPE ∑NFRs median ∑NFRs GM (c)
75
1.3 ng/dm2 (BzBP) to 127 ng/dm2 (DEP) in offices. Cotton had statistically higher concentrations
of DiBP, DnBP and DEHP than rayon (MWU, p<0.05) (Figure 4.1a). Cotton deployed in one
office had up to an order of magnitude higher concentrations of DnBP (4756 ng/dm2) and DiBP
(3056 ng/dm2) than measured in other offices. As this office was located in one of the homes, it
is possible that the cotton received elevated phthalate concentrations from personal care or
cleaning products (e.g., Schettler, 2006; Koniecki et al., 2011; Romero-Franco et al., 2011).
Cotton and rayon showed accumulation of both gas- (DEP, DiBP and DnBP) and particle-phase
(DEHP and DiNP) chemicals (Saini et al., 2015).
∑14PBDE concentrations ranged from 0.6–1.2 and 1.2–3.3 ng/dm2 cotton and rayon, respectively.
∑14PBDE concentrations in cotton and rayon were 7–8 times higher in offices than living rooms
and bedrooms (MWU, p<0.05). Higher concentrations of HFRs in offices than homes has been
reported previously (Zhang et al., 2011; Brommer et al., 2012; Cao et al., 2014; Li et al., 2015
inter alia).
BDE-47 and -99 constituted ≥ 70% of ∑14PBDEs concentrations in both fabrics (Figure 4.1b).
Concentrations of BDE-47 ranged between 0.28–45 ng/dm2 with the highest concentration
measured in offices (Table A3.2). This trend is consistent with results of Wilford et al. (2004),
who reported that BDE-47 and -99 had the highest concentration among PBDE congeners
measured in indoor air of Ottawa homes. BDE-47 and -99 are the main congeners in the
commercial penta-BDE mixture which was used mainly in flexible foam furniture and has been
reported previously at higher levels in air and dust than other congeners (Björklund et al., 2012;
Stapleton et al., 2012; Bradman et al., 2014; Abbasi et al., 2016). BDE-209 constituted 3-10% of
∑14PBDEs. BDE-17, -28 and -47 accumulated by fabrics were presumed to have been in the gas
phase whereas BDE-209 was presumed to be due to particle deposition (Cao et al., 2014;
Fromme et al., 2014; Saini et al., 2015). ∑10NFRs in homes and offices ranged from 0.6–1.6
ng/dm2 for cotton which were significantly lower than the 1.1–3.3 ng/dm2 accumulated by rayon
(MWU, p<0.05). ∑10NFR concentrations were significantly higher in offices than bedrooms for
both cotton and rayon (MWU, p<0.05); living rooms were statistically similar to both bedrooms
and offices. PBBz, PBT, HBB and EH-TBB constituted 88–93% of ∑10NFRs (Figure 4.1c).
PBBz concentrations were 4–7 times higher in rayon than cotton (MWU, p<0.05) whereas, EH-
76
TBB was 2–7 times higher in cotton than rayon in living rooms (MWU, p<0.05), bedrooms and
offices, respectively. We attributed these differences to greater analytical uncertainty at low
concentrations. The abundance of low-molecular weight NFRs such as PBBz and PBT again
confirmed gas-phase sorption (Saini et al., 2015). DBDPE, a deca-BDE replacement, that is
almost entirely particle sorbed, was also found in fabrics (up to 3% of ∑10NFRs), again
suggesting the accumulation of particle-phase chemicals by fabrics.
4.3.3 Uptake rates of SVOCs to fabrics
Uptake of 31 chemicals over 56 days was measured to obtain information about their sorption
kinetics and time to equilibrium. Weekly phthalate air concentrations measured with LV-AAS
ranged from 3.9±1.1 to 87±45 ng/m3 with BzBP and DEP having the lowest and highest
concentrations, respectively. The gas-phase percentages of phthalates were: DEP (100%), DiBP
(96%), DnBP (90%), BzBP (63%) and DEHP (40%). Relative standard deviation (RSD) among
weekly air concentrations of phthalates ranged from 28 to 51%. Among HFRs, eight chemicals
were consistently detected weekly by LV-AAS and showed relatively stable concentrations over
the 56 day time period (details reported by Saini et al., 2015). HFR concentrations ranged from
5.1±2.6 to 809±102 pg/m3 with PBBz and BDE-47 having the lowest and highest concentrations,
respectively. HFRs were 74–100% gas phase except for BDE-153 which was 30% gas phase
(Saini et al., 2015).
Although phthalate air concentrations were relatively high and thus analytical uncertainty was
low, fabrics showed inconsistent patterns of uptake over time (Figure A3.4). The reason for
inconsistent patterns of phthalate uptake was not clear. Among HFRs, nine chemicals showed
consistent linear uptake over 56 days of deployment with the exception of PBBz uptake by
cotton which appeared to plateau after 28 days (Figure 4.2). Uptake of the remaining HFRs by
both fabrics was either inconsistent or not detected, which could be due to their low air
concentrations (Saini et al., 2015). HFR concentrations accumulated by cotton and rayon on day
56 differed by factor of 0.7–2.8 when normalized to planar surface area (MWU, p=0.5; Table
A3.5). However when normalized to BET-SSA, rayon sorbed 3–10 times higher concentrations
compared to cotton (MWU, p=0.1; Table A3.6). Since uptake was during the linear stage, we
attributed this difference to either ‘dilution’ of sorbed chemicals by the larger surface area of
77
cotton than rayon or the difference in sorption that could be caused by varying degree of
polymerization and crystallization of cotton and rayon fibres (Mather and Wardman, 2011).
Latter reason is less likely at linear uptake stage due to non-equilibrium conditions. Below we
discuss chemical uptake rates according to planar surface area.
Figure 4.2. Uptake profiles of flame retardants by cotton (blue triangles) and rayon (red squares) over 56 days of deployment.
As with passive air samplers (PAS), the slope of the linear regression from the linear uptake
phase expresses the uptake rate of a chemical (Shoeib and Harner, 2002). The slope is
determined by plotting equivalent air volume, Veq (m3), estimated as the ratio of mass of a
chemical accumulated by fabric to the corresponding bulk air concentration measured with LV-
AAS, versus time.
Planar surface area-normalized uptake rates were calculated for eight HFRs with consistent
detection by both LV-AAS and fabrics. Statistically indistinguishable (MWU, p>0.05) uptake
rates of 0.35–0.65 and 0.42–0.92 m3/day.dm2 were estimated for all eight HFRs to cotton and
78
rayon, respectively, again suggesting similar uptake behaviour by the two fabrics when
considering the planar surface area (Table 4.1).
Table 4.1. Uptake rates (m3/day.dm2 fabric) of HFRs for cotton and rayon. (Note: planar surface area was used to normalize uptake rates).
Chemical Uptake rate (m3/day.dm2
fabric) ± Standard error of
slope
r2 Uptake rate (m3/day.dm2
fabric) ± Standard error of
slope
r2
Cotton Rayon
PBBz 0.35 ± 0.04 0.46 0.92± 0.05 0.91
PBT 0.63 ± 0.06 0.52 0.74 ± 0.05 0.83
BDE-17 0.34 ± 0.02 0.96 0.42 ± 0.01 0.97
BDE-28 0.45 ± 0.02 0.96 0.54 ± 0.02 0.94
BDE-47 0.62 ± 0.02 0.98 0.63 ± 0.05 0.79
BDE-66 0.47 ± 0.04 0.88 0.50 ± 0.03 0.93
BDE-100 0.53 ± 0.02 0.95 0.62 ± 0.07 0.67
BDE-99 0.65 ± 0.03 0.94 0.67 ± 0.06 0.74
Range 0.35-0.65 0.42-0.92
Mass transfer coefficients (MTC) or deposition velocities, which represent the velocity at which
a chemical is deposited on a surface, were estimated from the uptake rates and the fabric’s planar
surface area. MTCs for cotton and rayon ranged between 1.5–2.7 and 1.8–3.8 m/h, respectively
(Table A3.7), which were not significantly different (MWU, p>0.05). The MTCs were not
related to KOA or vapour pressure of the chemicals (Figure A3.5). These MTCs were 7 to 18
times lower than 27 m/h reported for DnBP to cotton jean fabric measured in a chamber
experiment by Morrison et al. (2015a) with relatively high air concentrations of up to 170 µg/m3.
The values measured here are similar to the range of 2.5–3.9 m/h reported for indoor SVOCs,
such as phthalates and HFRs, depositing to a large, flat indoor surface (Weschler and Nazaroff,
2008) and 2.4-6.7 m/h reported for the uptake of phthalates and HFRs to polyurethane foam
(PUF) PAS with a single bowl covering (Saini et al., 2015). The MTCs were also similar to those
measured for phthalates and HFRs depositing to polydimethyl siloxane (PDMS) and XAD-
79
pocket PASs by Okeme et al. (submitted a). The similarity of uptake rates of HFRs for cotton
and rayon in this experiment and PAS is consistent with air-side controlled uptake during the
linear uptake phase and independence from the physical-chemical properties of the chemical and
sorbent (Shoeib and Harner, 2002; Bartkow et al., 2005).
4.3.4 Fabric-air partitioning
The partition coefficient of a chemical is, by definition, the ratio of its concentration in a sorbent
phase and gas phase at equilibrium. Most chemicals measured in the uptake experiment were in
the linear uptake phase and had not reached equilibrium (Figure 4.2). As such, we report the ratio
of concentrations in fabric on day 56 (expressed as chemical mass per unit fabric volume
calculated from planar surface area and thickness) to concentrations in the gas phase (mass per
unit air volume) as dimensionless distribution coefficients, K’, C’fabric/ Cair (Tables A3.5 and
A3.8) to approximate the sorptive capacity of these fabrics after 56 days. Log K’ ranged between
6.5-7.1 and 6.6-7.0 for cotton and rayon, respectively, and were statistically similar (MWU,
p>0.05). Calculated as area normalized distribution coefficients, K’area (mass per unit fabric
planar area to mass per unit air volume) values were 1550-5770 and 2135-5320 m for cotton and
rayon, respectively (Table A3.8).
To assess the departure from equilibrium of fabrics deployed here for 56 days, we compared
these values with Kcellulose-air estimated using the polyparameter linear free energy relationship
(pp-LFER) model developed by Holmgren et al. (2012) for predicting the cellulose material-air
partition coefficient KMA:
RT lnKMA= -4700 + 3600A + 0B + 6200S + 610E + 2100L (1)
where, KMA is material (cellulose)-air partition coefficient, R is the gas constant (J/K.mol) and T
is temperature (K). Abraham solvation descriptors were as follows: A is hydrogen bond acidity,
B is hydrogen bond basicity, S is polarizability/dipolarity, E is the excess molar refraction, and L
is the logarithm of the partition coefficient between hexadecane and air.
Holmgren et al. (2012) calibrated the pp-LFER model using Abraham solvation parameters and
values of KMA taken from the literature. For chemicals for which measured KMA values were not
80
available, Holmgren et al. (2012) used material-water partition coefficients (KMW) for
conversion. Values of Abraham solvation parameter descriptors were obtained from the UFZ-
LSER database v 2.1 provided by Endo et al. (2015), which were available for PBT, BDE-28, -
47, -100 and -99.
Figure 4.3. Comparison of measured and modeled cellulose-air distribution and partition coefficients plotted as a function of Log KOA. Log KOA values were taken from EPI Suite 4.1 (USEPA, 2012) for NFRs and Harner and Shoeib (2002) for PBDEs.
We also estimated equilibrium partition coefficients for the same HFRs between cotton and
SVOCs in air using COSMO-RS solvation theory (Eckert and Klamt, 2002) as implemented in
the COSMOtherm program, version C30_1301 (Eckert and Klamt, 2013). The approach taken
was similar to that previously employed for such calculations between PUF (Parnis et al., 2015)
and PDMS (Okeme et al., submitted b) passive sampling media and air. Cotton was modeled
with the methyl-capped dimeric repeat unit of cellulose with the combinatorial term “on” as this
is an oligomeric liquid model. Computations of fully-solvated minimum-energy configurations
and screening charge densities were performed for all molecules and the cellulose model in the
“infinite dielectric” COSMO solvation environment, using the TURBOMOLE program
(TURBOMOLE V6.5, 2013) within the COSMOtherm suite. The TZVPD basis set was used,
with the “fine” cavity construction. COSMO-RS calculations were performed using the built-in
automatic Henry’s Law calculation option of COSMOtherm, generating air-cotton partition
y = 0.18x + 4.93
y = 1.50x - 6.79
y = 1.33x - 2.67
5
6
7
8
9
10
11
12
13
9.0 9.5 10.0 10.5 11.0 11.5
Log
K o
r K
' cotto
n-ai
r
Log KOA
LogK'cotton-air Log K COSMO-RS Log K pp-LFER
81
coefficients in bar units. These were converted to unitless (g/g) Kcellulose-air coefficients using the
estimated molar volume of the polymer model and the density of cotton used in the study.
Figure 4.3 and Table A3.7 compare measured K’ to modeled Kpp-LFER and KCOSMO-RS. The
estimated log Kpp-LFER were 9.9, 10.3, 11.3, 12.2 and 12.5 for PBT, BDE-28, -47, -100 and -99,
respectively, which were three to five orders of magnitude higher than K’cotton-air or K’rayon-air.
Except for PBBz and PBT, the estimated KCOSMO-RS values were two to three orders of magnitude
higher than measured K’cotton-air or K’rayon-air. Results from both pp-LFER and COSMO-RS
models support the conclusion that measured HFRs were far from reaching equilibrium after 56
days. KCOSMO-RS for PBBz and PBT were exceptions to this conclusion since these values were
0.4 to 0.8 orders of magnitude lower than measured K’cotton-air or K’rayon-air.
As expected, values of log Kpp-LFER and KCOSMO-RS increased as a function of log KOA whereas
measured log K’cotton-air or K’rayon-air showed no trend, which is consistent with the fabrics not
achieving equilibrium with most gas-phase concentrations and air-side controlled uptake. The
pp-LFER and COSMO-RS models represented the pure form of cellulose, which is a reasonable
representation of cotton and rayon that are essentially natural and regenerated forms of cellulose,
respectively.
K’cotton-air or K’rayon-air reported here were 1 to 2 orders of magnitude higher than Kvol reported by
Morrison et al. (2015a) for DEP (5.4 for log Kvol) and DnBP (5.6 for log Kvol) after a 10 day
experiment (with a 7–18 times faster deposition velocity). In comparison, estimated values of log
Kpp-LFER and log KCOSMO-RS (derived from log KOA using the equations in Figure 4.3) were 6.7 and
3.7 for DEP and 8.8 and 6.2 for DnBP, respectively. The log KCOSMO-RS values suggest that DEP
but not DnBP had reached equilibrium in the experiments of Morrison et al. (2015a).
The time to reach 95% of equilibrium ( t95, Shoeib and Harner, 2002) calculated using KCOSMO-RS,
was >10 years for PBDEs reported here (Table A3.8). The measured distribution coefficients and
estimated equilibrium partition coefficients point to the large sorptive capacity of these fabrics
for SVOCs. For high molecular weight SVOCs such as PBDEs, the time required to reach
equilibrium is likely longer than the lifespan of many articles of clothing, assuming no chemical
loss during laundering (Saini et al., Ch 5).
82
4.4 Discussion
The results presented here shed light on the process of SVOC uptake by fabrics and have
implications regarding the indoor fate of SVOCs and human exposure to these chemicals. The
results confirm SVOC uptake from indoor air of both gas and particle phases. The results are
consistent with air-side controlled uptake of these non-polar SVOCs, independent of the
physical-chemical properties of the chemicals and the material. We measured MTCs of 1.5–3.8
m/h over 56 days for HFRs that were indistinguishable from MTCs reported for PUF-PAS of
2.4–6.7 m/h (Saini et al., 2015), 1.9–8.5m/h to PDMS-PAS (Okeme et al., submitted a), and 2.5–
3.9 m/h depositing to a large, flat indoor surface (Weschler and Nazaroff, 2008) for the same
chemicals. Any difference in uptake rate of these non-polar SVOCs due to the hygroscopicity of
cotton and rayon was not evaluated. We noted that these rates do not account for air flow
differences in both the home and office deployment and chemical uptake studies. Variations in
air velocities can influence MTC and hence accumulation by controlling the air-side boundary
layer resistance. As well, these results do not account for the lack of clear uptake patterns and
hence ability to estimate deposition velocities of phthalates. Reasons for the erratic uptake
behaviour of phthalates over time are not evident and merit further investigation.
Apparent air-side controlled uptake of non-polar SVOCs to fabrics (and independence of uptake
from physical-chemical properties of the chemical or sorbent) has not been reported previously,
but is consistent with current understanding of SVOC uptake to passive air sampling media (e.g.,
Shoeib and Harner, 2002; Bartkow et al., 2005). Differences in accumulation between the fabrics
become apparent when uptake is normalized to BET-SSA rather than planar surface area. When
normalized to BET-SSA, rayon accumulated 3–10 times more HFRs than cotton. We
hypothesize that the difference is due to the ability of cotton to ‘dilute’ chemical due to its four
times larger BET-SSA than rayon, but it could also be possible due to other structural differences
between these two cellulose polymers such as degree of polymerization or crystalline structure.
The significance of difference in accumulation when considering BET-SSA is that cotton, with
lower accumulation per unit BET-SSA, is likely to have a longer linear uptake phase compared
to polyester, where this phase will dominate in reality given very long times to reach equilibrium.
Secondly, Saini et al. (Ch 3) hypothesized that differences in accumulation expressed according
83
to BET-SSA could have implications for availability of chemical for dermal uptake, i.e., a longer
uptake phase could imply lower availability.
These results have implications for the fate of SVOCs released indoors, of which concentrations
can be 10 times greater than outdoors (Rudel et al., 2010; Dodson et al., 2015 inter alia). Our
results indicate the high sorptive capacity of cotton and rayon for SVOCs with fabric-air
distribution coefficients, log K’cotton-air and K’rayon-air of 6.5-7 for phthalates and HFRs achieved
after 56 days. These distribution coefficients are much lower than equilibrium partition
coefficients, log Kpp-LFER and log KCOSMO-RS, which were up to 12 for PBDE, indicating that the
fabrics were far from reaching equilibrium. Indeed, time to reach equilibrium estimated using
KCOSMO-RS was >10 years for PBDEs.
Given the magnitude of distribution coefficients reported here for 56 days and equilibrium
partition coefficients, the magnitude of fabrics as indoor sinks of SVOCs is likely to be
significant since fabrics, both as clothing and home furnishings such as upholstery and drapes,
present the greatest surface area of all materials indoors (Molander et al., 2012). Models of
indoor chemical fate have not included fabrics and thus are likely to underestimate the reservoir
and residence time of SVOCs indoors (Bennett and Furtaw, 2004; Weschler and Nazaroff, 2008;
Zhang et al., 2009, 2011, 2014). The importance of fabrics as a sink has been noted with respect
to “3rd hand smoke” or residual tobacco contamination, chemical warfare agents and pesticides
that sorb and then desorb from fabrics after the source is removed (e.g., Matt, 2004; Cohen
Hubal et al., 2006; Feldman, 2010; Petrick et al., 2010).
Finally, these results have implications for human exposure. A growing literature indicates that
dermal uptake of SVOCs prevalent indoors could play a role in overall exposure (e.g, Abdallah
et al., 2016, 2015; Cohen Hubal et al., 2006; Johnson-Restrepo and Kannan, 2009; Weschler and
Nazaroff, 2012). As noted above, Morrison et al. (2016) found that wearing cotton clothing
exposed to phthalates increased dermal uptake relative to wearing clean clothing.
Using the calculations of Morrison et al. (2015a) and the average of uptake rates measured here
(0.5 m3/day.dm2 fabric), 2 m2 of clothing worn by a typical person could sequester chemical in
the equivalent of 100 m3 of air per day. This equates to the accumulation by clothing worn by
84
one person of 20 µg/day and 110 ng/day of phthalates and HFRs, respectively (based on
Σ6phthalates~200ng/m3 and Σ8HFRs~1100pg/m3 as reported in Section 4.3.3). These values also
translate to potential dermal exposure of 833 and 4.6 ng/hour for phthalates and HFRs,
respectively, assuming that all the chemicals accumulated by fabrics are transferred to skin
(Equation 1, Cohen Hubal et al., 2006).
4.5 Conclusions
Cotton and rayon were deployed indoors in homes and offices for 28 days and an uptake study
was conducted over 56 days to determine the accumulation behaviour of phthalates and HFRs to
cotton and rayon fabrics. These studies confirmed the accumulation of both gas- and particle-
phase chemicals to cotton and rayon. MTCs ranging between 1.5–3.8 m/h and uptake rates of
0.35–0.92 m3/day.dm2 planar surface area were independent of the type of fabric. These uptake
rates were not significantly different than uptake rates of SVOCs to passive air sampling media,
which suggests air-side controlled uptake. However, rayon accumulated more SVOCs than
cotton when considering BET-SSA, suggesting that cotton ‘dilutes’ the sorbed SVOCs given the
four times greater BET-SSA of cotton than rayon or that structural differences between these
cellulose-based fabrics was responsible. The results suggest that 2 m2 of cotton or rayon clothing
would accumulate chemicals from 100 m3 of equivalent air per day. The high sorptive capacity
of fabrics for SVOCs was demonstrated by distribution coefficients between fabric (planar
surface area) and air concentrations of 106.5 to 107 after 56 days. Fabric (cellulose)-air
equilibrium coefficients calculated using pp-LFER of Holmgren et al. (2012) and COSMO-RS
were as high as 1012 but that equilibrium would be achieved in >10 years. These results show the
large sorptive capacity of fabrics, such as clothing, for SVOCs which has implications for the
indoor fate of SVOCs and human exposure via dermal uptake.
Acknowledgements
We thank Dr. Tom Harner, Environment Canada for the valuable advice on the uptake study. We
also thank the home owners who participated in the sampling campaign. Funding was provided
by the Natural Sciences and Engineering Research Council of Canada (NSERC) and the Allergy,
Genes and Environment Network (AllerGen NCE) to MD, and University of Toronto
Scarborough to AS.
85
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Chapter 5: From clothing to laundry water: Investigating
the fate of semi-volatile organic compounds accumulated by
fabrics.
5.1 Introduction
Clothing plays a central role in our society with global exports of textiles estimated at $294
billion USD in 2011 (Fashion United, 2016). In Sweden, clothing, followed by household textiles
(e.g., upholstery and curtains), were estimated to have the greatest surface area of all materials
indoors (Molander et al., 2012). Thus, clothing is unique in the indoor environment as having the
largest surface area available for chemical accumulation from indoor sources and also being
subject to continual laundering. In terms of human exposure, Andersson et al. (2002) assumed
that on average, clothing covers 85% of human skin and can act as a barrier to exposure to
environmental and occupational airborne chemicals (e.g, Fenske et al., 2012; Macfarlane et al.,
2013; Moore et al., 2014). However, clothing can also be a source of exposure of intentionally
and unintentionally added chemicals (e.g., Curwin et al., 2005; Feldman, 2010). For example,
Morrison et al. (2016) conducted a series of experiments showing that clothing can reduce or
increase dermal uptake of phthalates at environmentally relevant concentrations, according to
whether the clothing was clean (i.e. not contaminated) or exposed to phthalates.
Textile fibres, from which fabrics are made, can be categorized according to origin into natural
(e.g., cellulose-based cotton and protein-based wool), semi-synthetic (e.g., regenerated
cellulose), and synthetic fibres (e.g., polyester synthesized from the terephthalic acid and
ethylene glycol monomers). Several studies have shown that sorption of polar semi-volatile
organic compounds (SVOCs) such as nicotine, is greater to fabrics of natural origin than non-
polar synthetic since natural fibres have polar functional groups such as the hydroxyl group
(cellulose and protein) or amide group and polar amino acid side chains (protein) (Piadé et al.,
1999; Petrick et al., 2010; Chien et al., 2011). The extent of sorption of polar compounds has
been suggested to be a function of the hygroscopicity of a fabric (Noble, 2000; McQueen et al.,
2008), which is consistent with the importance of polar functional groups. Non-polar compounds
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are expected to sorb preferentially to non-polar fabrics and materials (e.g., Won et al., 2000,
2001), where aromaticity is expected to play a role (e.g., Salloum et al., 2002; Chefetz and Xing,
2009). Recently Saini et al. (Ch 3, 4) conducted experiments under controlled and ambient
indoor conditions that confirmed accumulation by cotton, rayon and polyester of gas- and
particle-phase phthalates and halogenated flame retardants (HFRs). They reported similar
accumulation and uptake rates regardless of chemical or fabric when reported according to planar
surface area, which is consistent with air-side controlled uptake. However, cotton accumulated
less than rayon or polyester when expressed according to Brunauer–Emmett–Teller specific
surface area (BET-SSA) which they ascribed to either dilution by cotton’s large BET-SSA or a
higher affinity of, in particular, polyester, for these non-polar chemicals.
Clothing has also been hypothesized to transfer HFRs such as polybrominated diphenyl ethers
(PBDEs) and organophosphate esters (OPEs) from indoors to outdoor surface waters via waste
water as a result of laundering (Schreder and La Guardia, 2014). Based on the similarity in flame
retardant profiles in dust and laundry water, Schreder and La Guardia (2014) hypothesized that
this transfer occurs from indoors to outdoor waters due to the release of HFRs during laundering,
where the HFRs were accumulated by clothing via contaminated dust or air. Additionally, they
showed that the transfer was greatest for soluble OPEs.
Based on the findings and explanations in the literature, it stands to a reason that physical-
chemical properties of SVOCs as well as fabrics play a role in their uptake to clothing and
release during laundering. Our goal was to investigate the role of clothing as a sorbent of indoor
SVOCs and a source to outdoors through laundering. We hypothesized that the physical-
chemical properties of the SVOCs and fabrics control uptake from air and release to laundry
water. The study was designed to first investigate uptake followed by the release of SVOCs after
their accumulation in fabrics, by tracking the mass released to laundry water, remaining in
fabrics after laundering, and the contribution of clothes drying. We focused on two groups of
SVOCs that are ubiquitous indoors, namely phthalates and flame retardants (HFRs and OPEs).
Phthalates and some OPEs are also used as plasticizers and a growing literature documents their
elevated levels indoors (e.g., Stapleton et al., 2009; Dodson et al., 2012, 2015; Bradman et al.,
2014 inter alia).
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5.2 Methods
5.2.1 Test fabrics
Fabrics purchased from Testfabrics, Inc. (Pennsylvania, USA) were plain weave cotton
(bleached, unmercerized) and polyester (poplin) with densities of 120 and 127 g/m2 of fabric and
specific surface areas of 1.17 and 0.14 m2/g, respectively, measured the BET adsorption method
(BET-SSA). Fabrics were cut into 35×35 cm2 squares and were pre-cleaned by pressurized liquid
extraction using accelerated solvent extractor (ASE) (Dionex ASE 350, Thermo Scientific, USA)
with hexane (HPLC grade, Fisher scientific). Cleaned fabric squares were dried in a desiccator
and then fixed to a metal frame for deployment.
5.2.2 Experimental design
Three groups, 10 squares each of cotton and of polyester fabrics, were hung 1.5 m above ground
in an office located at University of Toronto. Fabrics were removed from the frames after 30
days and each piece was wrapped in clean aluminum foil for storage at -4°C until extraction.
Group 1 samples were extracted using ASE with hexane, dichloromethane (DCM) and acetone
(2:1:1, v/v) (HPLC grade, Fisher scientific) immediately after deployment. Group 2 samples
were laundered after deployment to collect laundry water and then were dried in a desiccator
after which they were extracted (again using ASE with hexane, DCM and acetone, 2:1:1). Group
3 was laundered and then dried in an automatic dryer (LG electric dryer, DLEX3250R model) to
collect lint. The dried fabrics and lint were extracted as per the other groups.
5.2.3 Laundering, drying, extraction and analysis
Laundering: Fabrics were laundered in 500 ml glass bottles with polypropylene caps (Pyrex,
Fisher Scientific). Bottles and caps were pre-washed with a soap solution followed by baking
glass bottles for 12 hours at 250°C. Both caps and bottles were rinsed with hexane, DCM and
methanol before use. For fabric laundering, 500 ml of HPLC grade water (Fisher Scientific),
stored at room temperature, was added to bottles along with 2–3 drops of Natural 2X
concentrated liquid laundry detergent (Seventh Generation, Burlington, VT, USA). A list of
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detergent ingredients is given in supporting information, SI (Appendix 4). No target chemicals
were detected in the laundry detergent which is consistent with Schreder and La Guardia (2014).
Bottles were manually shaken to mix the soap and water before adding fabrics. With fabrics,
capped bottles were shaken using wrist action shaker (Burell Scientific, LLC., USA) for 30
minutes to imitate mixing by a washing machine. After fabrics were laundered, laundry water
was transferred to Teflon separatory funnels (TSF) for liquid-liquid extraction. Bottles
containing fabrics were rinsed twice with 250 ml of HPLC grade water and the rinse water, along
with laundry water obtained from squeezing the fabrics (using tweezers), were combined with
the laundry water in the TSF for extraction.
Drying (in a dryer): Group 3 fabrics were dried in a five year-old LG electric dryer. Before
drying, lint was removed from the lint trap and the internal surface of dryer (stainless steel tub)
and lint trap were wiped with isopropanol (HPLC grade, Fisher Scientific). Two sets of blanks
(dried and not dried in dryer) were collected before drying test samples. In the first set, two
pieces of pre-cleaned cotton and polyester squares were separately swirled thrice inside the dryer
and were wrapped in clean aluminium foil to dry in a desiccator before extraction. The second
set of blanks consisted of two pre-cleaned pieces of cotton and one of polyester that were dried in
the dryer and then wrapped in clean aluminium foil for further extraction. The drying cycle of the
dryer was set at medium heat for 20 minutes. Cotton and polyester fabrics (group 3, 10 pieces of
each fabric) were dried separately that had been laundered after deployed for 30 days. Lint was
collected from the lint trap after the drying cycles of cotton and polyester fabrics. Dried fabric
and single lint samples (each of cotton and polyester weighing 0.02 and 0.23 g, respectively)
were wrapped in clean aluminium foil until extraction.
Extraction: Fabrics and lint were extracted using the ASE with hexane, DCM and acetone
(2:1:1, v/v) at the operating conditions listed in SI. The in-cell extraction and clean up method of
Saini et al. (2015) was modified by adding 5 g of pre-cleaned silica gel (Fisher Scientific) to the
ASE cells along with 10 g of anhydrous sodium sulfate (Fisher Scientific) for clean-up of the
extract. The clean extract was reduced to 0.1 mL under a gentle stream of nitrogen in a Zymark
Turbo-vap (TurboVap II concentration workstation, Caliper Life Science, Massachusetts, USA)
followed by reconstituting the final volume to 0.5 ml in GC vials using isooctane (HPLC grade,
Fisher scientific).
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Laundry water was liquid-liquid extracted thrice using DCM as described by Schreder and La
Guardia (2014). Before extraction, TSF was rinsed twice with acetone followed by DCM. After
collecting laundry water (~1 L) in TSF, 50 ml of DCM was added and gently shaken (manually)
for two minutes. Two phases (water and DCM) were allowed to separate after which DCM was
drained slowly into a pre-cleaned glass funnel filled with glass wool and sodium sulfate, and was
collected in a Turbo-vap glass tube. The same procedure was repeated twice and the three
extracts were combined after which the sample was reduced using Zymark Turbo-vap as
explained above.
Analysis: Five phthalates, 14 polybrominated diphenyl ethers (PBDEs), 11 new flame retardants
(NFRs) and eight OPEs were analysed. Detailed information of target chemicals is given in
Table A4.1. The three isomers of TCPP were treated as distinct chemicals, however their distinct
physical-chemical properties have not been reported in literature (Truong et al., in prep). We use
the notation for these isomers recommended by Truong et al. (in prep). Samples were analysed
using Agilent 6890N Gas chromatograph coupled with Agilent 5975 inert mass-spectrometer
(GC-MS). Full details of the operating conditions are given in SI.
5.2.4 QA/QC
Blanks and recoveries were monitored throughout the sampling and analytical measurements.
Field blanks were collected during the sampling campaign and extracted and analysed along with
laboratory blanks and samples for each group of fabrics. Surrogate standards were added prior to
extracting fabrics, lint and laundry water samples to check recoveries. DEHP-d4 was used as
surrogate standard for phthalates; mPBBZ, mHBB (mass-labeled) and F-BDE-100, -154 and -
208 (fluorinated BDEs) were used as surrogate standards for HFRs and dTnBP and mTPhP were
surrogates for OPEs (Accustandard, USA and Wellington laboratories, Canada). Average
recoveries for surrogates were 60% (DEHP-d4), 55–80% (HFRs) and 50–65% (OPEs). The
extraction method was validated by extracting and analysing spiked fabric samples. Average
recoveries of spiked analytes ranged between 58–130% for phthalates, 79–110% for BDEs
(except BDE-209), 55–170% for NFRs (except OBTMPI and DBDPE) and 70–110% for OPEs.
The data were quantified using an internal standard Fluoranthene-d10, BDE-118 and Mirex for
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phthalates, HFRs and OPEs, respectively, which were added to the final volume of the extract
before GC analysis.
Microsoft Office Excel 2007 was used for descriptive data analyses. Non-parametric statistical
tests (Mann-Whitney U test, MWU, and Kruskal-Wallis ANOVA, KWA) were performed using
STATISTICA software version 8 (StatSoft Inc., Oklahoma, US).
5.3 Results
The total masses obtained for three chemical classes from fabrics in groups 1, 2 and 3 that
underwent different treatments (i.e. ASE extraction only, washing and drying in desiccator or
dryer followed by ASE extraction) were statistically indistinguishable (KWA, p>0.2; Table
A4.3, A4.4).
5.3.1 Chemical accumulation by fabrics normalized to planar surface area
(group 1)
Out of 36 chemicals, 23 chemicals had ≥ 70% detection in the samples (except TnBP in polyester
with 50% detection) and are discussed further. We note that high detection limits of chemicals
such as BEH-TEBP, DBDPE and BDE-209 (Table A4.2) could have limited their detection in
samples. When considering planar surface area normalized concentrations, ∑5phthalates were 50
and 22 times higher than ∑10HFRs and three and six times higher than ∑8OPEs in cotton and
polyester, respectively. The following comparison of concentrations is based on the planar
surface area of fabrics followed by comparison based on BET-SSA.
Phthalates
Detection frequencies of the five target phthalates were ≥ 90% except for 70% for DiBP and
DiNP in polyester. The relative standard deviation (RSD) was < 35% except for 53% for DiNP
in cotton (Table A4.3). Cotton had significantly higher concentrations of DiBP and DnBP than
polyester (MWU, p<0.001), whereas, BzBP, DEHP and DiNP were statistically similar (MWU,
p>0.05) (Figure 5.1a, Table A4.3). DEHP had highest concentration in cotton (1360±492 ng/dm2
fabric) and polyester (1091±460 ng/dm2 fabric), constituting 40 and 60% of ∑5phthalates,
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respectively. DiBP and DnBP were nine and five times higher in cotton (650 and 914 ng/dm2,
respectively) than polyester (70 and 179 ng/dm2, respectively). Phthalates have a wide variety of
usages: low molecular weight phthalates such as DiBP and DnBP are mainly used in adhesives,
waxes, cosmetics, personal care or cleaning products, whereas higher molecular weight BzBP,
DEHP and DiNP are mainly used as plasticizers (Kavlock et al., 2002a, 2002b, 2002c; Schettler,
2006; Romero-Franco et al., 2011; Kim et al., 2013). Relatively high concentrations of phthalates
in indoor environments compared to other SVOCs have been reported previously (Rudel et al.,
2003, 2010; Bergh et al., 2011; Dodson et al., 2015; Saini et al., 2015, Ch 4).
HFRs
Ten HFRs had ≥ 90% detection frequency with RSDs of < 35% except for 48 and 64% for EH-
TBB in cotton and polyester, respectively (Table A4.3). Cotton and polyester showed statistically
similar accumulation of HFRs (MWU, p>0.05) except for BDE-99 which was significantly
higher in polyester than cotton (MWU, p<0.05) (Figure 5.1b, Table A4.3). BDE-47 had the
highest concentration accumulated of the 10 HFRs reported, with an average of 46±11 and
53±18 ng/dm2 in cotton and polyester, respectively, constituting 70% of the ∑10HFR mass
measured in both fabrics. BDE-99 contributed ~20% of ∑10HFR with an average of 10±2.9 and
15±4.5 ng/dm2 in cotton and polyester, respectively. The abundance of BDE-47 and -99 among
HFRs indoors has widely been reported (Zhang et al., 2011; Dodson et al., 2012, 2015; Bradman
et al., 2014; Abbasi et al., 2016).
Among NFRs, HBB and EH-TBB were the main contributors with average levels of 0.4–1.3
ng/dm2 fabric. HBB is mainly reported to be used as an additive flame retardant in plastic, wood
and textile goods (Yamaguchi et al., 1988; Covaci et al., 2011). EH-TBB, along with BEH-
TEBP, are the main constituents of Firemaster 550 (FM 550) that is used as major penta-BDE
replacement in foam products (Stapleton et al., 2008, 2012). The low detection of BEH-TEBP
was likely due to relatively high detection limits for this as well as other HFRs (Table A4.2).
OPEs
The detection frequency of the eight OPEs analyzed was ≥ 70% except 50% for TnBP in case of
polyester (Table A4.3). OPE concentrations (except TCEP) were up to seven times higher in
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cotton than polyester (MWU, p<0.03) (Figure 5.1c, Table A4.3). ∑3TCPP (-1,-2 and -3)
dominated the OPEs with average total concentrations of the three isomers of 933±582 and
208±152 ng/dm2, constituting 87 and 72% of ∑8OPEs in cotton and polyester, respectively. OPE
concentrations were highly variable, with RSDs ranging between 35 to 85%, some of which
could be attributed to variable recoveries.
Figure 5.1. Average concentrations of phthalates (a), HFRs (b), and OPEs (c) accumulated by cotton and polyester, expressed as ng/dm2 planar surface area of fabric. Error bars indicate standard deviation. Note: Y-axis is a log scale for HFRs and OPEs but is linear for phthalates. * represents a statistically significant difference between cotton and polyester (p<0.05). Note: TCiPP is referred as TCPP-1.
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Overall, ∑8OPEs in cotton and polyester were 17 and 4 times higher than ∑10HFRs, respectively.
OPEs such as TCPP, TDCiPP are used as replacements for phased out penta-BDE in PUF
products (Stapleton et al., 2009, 2011). High levels of OPEs have been reported indoors, e.g.,
67–140 µg TCPP-1/g dust from US homes (Dodson et al., 2012; Schreder and La Guardia, 2014;
Stapleton et al., 2014), 70 µg TDCiPP/g dust in California early childhood education facilities
(Bradman et al., 2014), 32 µg Σ7OPEs/g dust in German offices (Brommer et al., 2012), 164 µg
Σ9OPEs/g dust collected from the surfaces around electronics in Dutch homes (Brandsma et al.,
2014), and 962 ng Σ8OPEs/g dust in Egyptian homes (Abdallah and Covaci, 2014). TCEP, an
impurity (14% by weight) in the commonly used commercial mixture Antiblaze V6, is reported
to be used in PUF in automotive and furniture applications (European Union, 2007) and has also
been measured in foam collected from baby products with concentrations of V6 as high as 4.6%
of foam mass (Fang et al., 2013). Apart from their uses as flame retardants, OPEs such as TnBP,
TPhP and EHDPP are also used in hydraulic fluids, adhesives, cosmetics and/or as plasticizers
(Van der Veen and de Boer, 2012; Wei et al., 2015).
Chemical accumulation by fabrics normalized to BET specific surface area
Concentrations of higher molecular weight phthalates (BzBP, DEHP and DiNP) and HFRs that
were similar on a per unit planar area of fabric, were significantly lower (6–12 times) in cotton
than polyester per unit BET-SSA (MWU, p<0.05) (Figure A4.1). OPE concentrations that were
significantly higher in cotton than polyester per unit planar area, were either similar (TnBP,
TCPP-1, -2, and -3) or 3–9 times lower in cotton (TCEP, TDCiPP, TPhP and EHDPP) than
polyester (MWU, p<0.05) when normalized to BET-SSA. The factors of 6–12 by which cotton
accumulated lower concentrations than polyester, is similar to the 8-fold difference between
BET-SSA of cotton and polyester.
5.3.2 Chemical release to laundry water (group 2)
The release of chemicals from fabric to laundry water was consistent between cotton and
polyester with some notable exceptions that are discussed below (Figures 5.2 and A4.2; Table
A4.4; Equation A4.1 and A4.2). As expected, the percentage of accumulated chemical released
to laundry water was highest for chemicals with high water solubility.
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Figure 5.2. Percentage distribution of chemicals released to laundry water and remaining sorbed to cotton (top) and polyester (bottom). Percentages are based on concentrations in laundry water (ng/L.dm2) and remaining on fabric (ng/dm2).
Specifically, the percentage of phthalates released to laundry water was up to 100% for DiBP
released with concentrations of 454±79 and 59±20 ng/L.dm2 of cotton and polyester,
respectively. Eighty percent of DnBP and BzBP in cotton (565±137 and 196±52 ng/L.dm2,
respectively) were released to laundry water, whereas 50 to 70% (118±57 and 155±31 ng/L.dm2,
respectively) were released from polyester. For DEHP, ~35% was released in laundry water from
cotton and polyester (362±296 and 339±322 ng/L.dm2, respectively), whereas no release of
DiNP to laundry water was detected for both fabrics. Less than 10% of accumulated HFRs, in
general, were released to laundry water (0–0.67±0.2 ng/L.dm2) and >90% of the mass remained
on laundered cotton (0.06±0.02–33±15 ng/dm2) and polyester (0.10±0.04–61±15 ng/dm2). OPEs
showed very different behaviour than HFRs, with >80% release of chemicals accumulated by
cotton (16±5–1684±77 ng/L.dm2) and polyester (1.5±1.5–168±73 ng/L.dm2). Exceptions to this
high release were TPhP and EHDPP for which 50% and <15% were released, respectively
0%
20%
40%
60%
80%
100% %
Dis
trib
utio
n Cotton Released in laundry water Left on fabric
0%
20%
40%
60%
80%
100%
% D
istr
ibut
ion
Polyester
100
(Figure 5.2, Table A4.4). Schreder and La Guardia (2014) also reported the abundance of
∑3ClOPEs in laundry water with 18 times greater concentrations than ∑9PBDEs.
5.3.3 Effect of drying (group 3)
The mass of chemicals remaining on fabrics was similar for those laundered followed by drying
in a desiccator (group 2) versus those laundered followed by drying in an electric dryer (group 3)
(MWU, p>0.5, Table A4.4) with the notable exception of DBDPE.
Group 3 fabrics showed high concentrations of DBDPE of 106±45 and 211±44 ng/dm2 in cotton
and polyester, respectively, whereas this chemical was not detected in group 1 or 2 fabrics (in
part because of high detection limits). DBDPE in group 3 fabrics appears to have originated from
the electric dryer since field blanks (clean fabrics not deployed) that were also dried for 20
minutes, had similarly high concentrations of DBDPE. We then compared concentrations of
these fabrics with a single sample of dryer lint collected after drying 10 fabric squares of each of
cotton and polyester. DBDPE concentrations in lint were 17000 and 8500 ng/g of lint in cotton
and polyester, respectively, compared with 7 (cotton) to 18 (polyester) ng/g dried fabric (Figure
5.3). We have not interpreted the differences in DBDPE concentrations in cotton versus polyester
fabrics and lint reported here because of the small sample sizes. Stapleton et al. (2005) and
Schecter et al. (2009) reported BDE-209 at levels up to 2890 and 2149 ng/g in dryer lint
collected from homes, respectively.
These results indicate that the dryer was the source of DBDPE, which is a major replacement for
decaBDE and has been found to be used in electrical and electronic equipment, including its
components (Covaci et al., 2011; Abbasi et al., 2016). In this case, DBDPE is likely released
from the dryer’s electrical components such as wiring and possibly plastic parts as well. These
results suggest that clothes dryer can act as a source of DBDPE to dried fabrics and to outdoors
via its ventilated air.
101
Figure 5.3. Concentrations of DBDPE in pre-cleaned and deployed fabrics dried for 20 minutes in an electric dryer (a), and lint collected from the lint trap of dryer (b). Note: Single lint sample was collected separately for each of cotton and polyester.
5.3.4 Chemical accumulation and release as a function of physical-chemical
properties
Factors related to the differences between chemicals accumulated from air by cotton and
polyester from air was investigated by plotting the difference, (Ccotton – Cpolyester)/Ccotton, against
physical-chemical properties. The physical-chemical properties were obtained from EPI Suite
software tools (version 4.11, USEPA, 2012).
On a planar surface area basis, the difference showed a significant inverse relationship with the
octanol-water partition coefficient (KOW) (r2=0.60, p<0.001, Figure 5.4). The difference in
accumulation also showed a weak, inverse relationship with the Henry’s law constant (HLC, Pa-
m3/mol), and a significant positive relationship with solubility (r2=0.32, p=0.005, Figure A4.3),
but was not related to KOA (figure not shown) and polarizability (Stenzel et al., 2013) of eight of
the test chemicals for which we obtained data (Figure A4.4). These relationships between the
difference accumulated by cotton versus polyester and physical-chemical properties (or lack
thereof) were preserved when concentrations were normalized to BET-SSA (Figure A4.5).
0 5
10 15 20 25 30
ng/g
fabr
ic
0
5000
10000
15000
20000
ng/
g lin
t
(a) (b)
102
Figure 5.4. Difference in chemical accumulation from air (Ccotton – Cpolyester)/Ccotton, normalized to planar surface area of fabric, plotted against octanol-water partition coefficient (Log KOW). Red dotted line indicates zero on vertical axis. Note: TCEP, being an outlier, was excluded; if included, gives r2 =0.4, p<0.001).
Next, we investigated the relationship between the percentages of chemicals released to laundry
water versus that remained sorbed to fabrics as a function of physical-chemical properties. The
percentage of total chemical released into laundry water showed an inverse sigmoidal
relationship with log KOW (Figure 5.5a): chemicals with log KOW <4 which were OPEs (TnBP,
TCEP, TCPP and TDCiPP) showed >80% release to laundry water, whereas chemicals (all
HFRs) with log KOW >6 showed <10% release. Phthalates were in the middle of these two
groups. DiBP, DnBP and BzBP with log KOW of 4.5–5 had 50–100% release with increasing
KOW, whereas <30% of DEHP and DiNP with log KOW >8 were released. The shape of this curve
is analogous to gas-particle partitioning of SVOCs as a function of vapour pressure and KOA
shown by Harner and Bidleman (1998). As expected, the percentage released to laundry water
showed a sigmoidal relationship with water solubility and inverse sigmoidal relationship with
HLC (with TnBP, DnBP and DiBP as outliers) (Figures A4.6 and A4.7). Further, a significant
(p<0.05) positive relationship was found between the percentage of accumulated chemical
released to laundry water and the polarizability of eight of the 24 chemicals reported here, with
the exception of DnBP (Figure 5.5b). Overall, the greatest release was measured for the most
highly polarizable long-chain aliphatic OPEs, TDCiPP and TCEP (and presumably TnBP as
well), was less for aromatic TPhP, and was least for the PBDEs that have minimal polarizability.
This relationship merits further investigation with measures of polarizability of more chemicals.
y = -0.19x + 1.34 r² = 0.60, p<0.001
-0.60 -0.40 -0.20 0.00 0.20 0.40 0.60 0.80 1.00
2 4 6 8 10
Diff
eren
ce in
sorp
tion
cott
on v
s pol
yest
er
Log KOW
103
Figure 5.5. Percentage of accumulated chemical released to laundry water from cotton (blue diamonds) and polyester (red squares) as a function of (a) octanol-water partition coefficient (KOW), and (b) polarizability of eight chemicals. Black, purple and green ellipses enclose phthalates, HFRs and OPEs, respectively.
A relationship was not found between the percentage released to laundry water and gas-particle
partitioning of phthalates and HFRs reported for the same location by Saini et al. (2015a, Ch 4)
(Figure A4.8; gas-particle distribution was not available for OPEs). However, this graph clearly
distinguished phthalates with higher release rates to laundry water, from HFRs with lower
release rates, regardless of their gas-particle partitioning. From this we conclude that the release
of chemicals accumulated by fabrics to laundry water was not related to whether the chemicals
were sorbed from the gas phase or accumulated by particle-phase deposition to fabrics.
Finally, we investigated the relationship between the difference in accumulation of cotton versus
polyester and the percentage released to laundry water. We found that most aliphatic OPEs that
sorbed more to cotton than polyester had >80% release to laundry water (Figures 5.6 and A4.9).
HFRs, which showed no difference between accumulation by cotton versus polyester, had <10%
release to laundry water, while chemicals with unsubstituted benzene rings (BzBP, TPhP and
EHDPP) and DEHP and TCEP showed intermediate behaviour.
104
Figure 5.6. The difference of chemical accumulation from air (Ccotton – Cpolyester)/Ccotton, normalized to planar surface area of fabric, plotted against the percentage released to laundry water. The dotted red line indicates zero on horizontal axis.
5.4 Discussion
These results have implications regarding clothing as a sink for chemicals released indoors, for
transferring chemicals from indoors to outdoors, and for human exposure.
In terms of clothing acting as a sink, our results suggest that physical and chemical properties of
fabrics as well as chemicals account for chemical accumulation. We hypothesize that the high
specific surface area of a fabric can ‘dilute’ accumulated chemical during non-equilibrium
uptake, regardless of the physical-chemical properties of the chemical. The data showed that, on
a planar surface area basis, cotton accumulated more or equal concentrations compared to
polyester. Considering BET-SSA, cotton accumulated equal or lower concentrations than
polyester. The hypothesis of chemical dilution was also able to account for comparable
concentrations of HFRs accumulated by cotton and rayon on a planar surface area basis, but
lower concentrations in cotton than rayon on a BET-SSA basis (Saini et al., Ch 4). Both fabrics
consist of cellulose but the BET-SSA of cotton exceeds that of rayon. Previous studies have
noted the importance of the large surface area of natural versus synthetic fabrics in terms of
chemical accumulation (e.g., Petrick et al., 2010).
0%
20%
40%
60%
80%
100%
-0.60 -0.40 -0.20 0.00 0.20 0.40 0.60 0.80 1.00
% r
elea
sed
to la
undr
y w
ater
Difference
Cotton Polyester
TCEP
BzBP
DEHP
TPhP
EHDPP
DnBP
DiBP OPEs
DiNP
HFRs
105
Overlaid on the physical phenomenon of chemical dilution, is the influence of physical-chemical
properties of the chemical and fabric. Our results showed that when considered on a planar
surface area basis, cotton accumulated more polar chemicals such as OPEs than polyester, and
that the tendency for accumulation by cotton versus polyester was a function of the chemical’s
KOW. This relationship was preserved when concentrations were normalized to BET-SSA,
although the difference was negative (i.e., polyester tended to accumulate more than cotton). The
observation of greater sorption of polar compounds to polar fabrics (such as natural fabrics) has
been noted by others with two explanations offered: polar chemicals bind to reactive polar sites
or dissolve into a water surface film that develops as a function of a fabric’s hygroscopicity
(Piadé et al., 1999; Petrick et al., 2010; Chien et al., 2011). The finding of a significant
relationship between the differences in chemical accumulation by cotton versus polyester as a
function of KOW is consistent with the explanation of dissolution into a surface water film that
could develop on polar fabrics, although this requires further testing. Furthermore, the results
support the expectation that polyester has a greater affinity for non-polar SVOCs, which could be
due to the aromaticity of the chemical and sorbent (e.g., Salloum et al., 2002, Saini et al., Ch 3).
The hypothesis of air-side controlled uptake was inferred based on the similarity of uptake rates
of HFRs and phthalates by cotton and rayon, assuming planar surface area and that equilibrium
had not been reached (reaching 95% of equilibrium was estimated to take >10 years for PBDEs,
Saini et al., Ch 4). But if “chemistry” plays a role in chemical-fabric accumulation, can uptake be
strictly air-side controlled? Results presented here support the hypothesis of air-side controlled
uptake for HFRs and high molecular weight phthalates; the influence of KOW on uptake becomes
evident when considering OPEs. The hypothesis of air-side controlled uptake, independent of the
sorbent characteristics, needs to be tested for the highly soluble OPEs.
During laundering, OPEs, especially those with aliphatic chains, were nearly entirely released
from fabrics to water. Moreover, cotton, which accumulated more OPEs than polyester, is a
particularly efficient conduit for these chemicals from indoors to outdoors via laundry water.
Conversely, non-polar SVOCs remain sorbed to both polar and non-polar fabrics during
laundering, making fabrics a continual sink for these chemicals. Phthalates and aromatic OPEs
(e.g., TPhP and EHDPP) showed intermediate behaviour that depended on their physical-
106
chemical properties. Thus, our results confirm that clothing efficiently conveys polar SVOCs
emitted indoors to outdoor surface waters via laundering (Schreder and La Guardia, 2014).
In waste water treatment plants (WWTPs), OPEs, particularly chlorinated compounds, have
<20% removal rates and partition to the final liquid effluent (rather than biosolids) because of
their high water solubility (e.g., Meyer and Bester, 2004; De Silva et al., 2015). Thus, the release
of OPEs from clothing during laundering provides an explanation for their relatively high
concentrations measured in WWTP and receiving waters, as hypothesized by Schreder and La
Guardia (2014).
In contrast, HFRs are largely retained by fabrics, with minimal release to laundry water.
However, HFRs (notably PBDEs) have been measured at relatively high levels in WWTP
influent and effluent (Melymuk et al., 2014; Schreder and La Guardia, 2014; De Silva et al.,
2015). Since HFRs are found in high concentrations in indoor dust, we suggest that HFRs in the
WWTP stream could originate from the accumulation by, and release of dust from clothing
during laundering, in addition to other cleaning activities (Takigami et al., 2009). This suggestion
is not necessarily at variance with our results that showed the independence of chemical release
to laundry water according to the extent to which a chemical was in the gas or air-borne particle
phase. Rather, clothing comes in contact with coarse dust on surfaces, the accumulation and
release of which was not tested here.
If we assume that one medium load of cotton laundry weighs ~4500 g (estimated by measuring
own laundry bag) and cotton has a density of 120 g/m2 (similar to the cotton fabric used here),
one medium load of cotton laundry would contain about 38 m2 of fabric. Thus, a single load of
laundry would release 6000, 400 and 1000 µg of ∑5phthalates, ∑5PBDEs and ∑8OPEs,
respectively, per litre of laundry water (calculated based on the averaged total of laundry water
concentrations measured here for phthalates, PBDEs and OPEs of 1580, 1.0 and 2670 ng/L.dm2,
respectively). A typical laundry machine that uses about 50 L of water per load (Energy star,
2015) would thus release 300, 2 and 500 mg of phthalates, PBDEs and OPEs, respectively, per
laundry load to waste water. The estimates for PBDEs and OPEs are an order of magnitude
higher than those of Schreder and La Guardia (2014) which could be due to our deployment of
fabrics in an office with higher FR concentrations, in comparison to their estimates for homes
107
with lower FR concentrations (e.g., Zhang et al., 2011; Brommer et al., 2012; Abdallah and
Covaci, 2014; Saini et al., Ch 4).
Although not estimated here, release of chemicals to the outdoor environment is also suggested
via ventilated air from clothes dryers. This release mechanism needs to be considered in addition
to indoor ventilation that has been found to transfer SVOCs from indoors to outdoors (Zhang et
al., 2009; Newton et al., 2015).
In regards to human exposure, we consider two cases. The first case is the accumulation of polar
SVOCs by fabrics. These chemicals are expected to undergo accumulation and loss through
normal wear and wash cycles, regardless of the type of fabric. After laundering, the fugacity
gradient between air and laundered “clean” fabric will favour chemical sorption to fabric.
According to the conceptual model presented by Morrison et al. (2016), frequently laundered
clothing should act as a barrier for the dermal sorption of these polar chemicals from air.
However, the potential for OPEs in clothing to be dissolved into sweat merits investigation,
noting that TCEP, TCPP and TDCPP can be dermally absorbed and that absorption is a function
of water solubility (Abdallah et al., 2016).
The situation is different for the accumulation of non-polar SVOCs where minimal chemical is
lost during laundering. This is consistent with Munk et al. (2001) and McQueen et al. (2014) who
found that odorants chemicals, such as medium-chained carboxylic acids, were incompletely
removed by laundering, even after multiple wash-cycles. They also found that losses during
multiple cycles of laundering were least for polyester and ascribed this to the hydrophobic nature
of polyester that impedes the removal of odorants. Since equilibrium may not be reached
between HFRs in air and cloth for years (Saini et al., Ch 4), these data suggest that non-polar
chemicals could continue to accumulate in clothing over the lifetime of the garment. We suggest
that mechanistic modeling is necessary to assess whether the fugacity gradient between clothing
and skin is sufficient after prolonged chemical accumulation to allow for dermal uptake, given
the very large sorptive capacity of these fabrics and ‘competition’ between this sorptive capacity
and skin oils.
108
Phthalates, especially the lower molecular weight compounds, behave mid-way between the
polar OPEs and non-polar HFRs. Here the empirical evidence of Morrison et al. (2016) is
informative, showing that clean cotton clothing acted as a barrier to dermal uptake of low
molecular weight DEP and DnBP whereas exposed clothing acted as a source to increase dermal
uptake.
5.5 Limitations and Uncertainties
Several limitations need to be considered in this study. First, chemical accumulation was
assessed in a single office. Chemical concentrations of some compounds such as HFRs tend to be
higher in offices than those in residential settings, although the levels present in this office were
comparable to those reported for other offices (Saini et al., Ch 2 and 4). Experiments did not
manipulate relative humidity which has been shown to alter the uptake of polar compounds to
polar fabrics (Piadé et al., 1999; Petrick et al., 2010). The controlled accumulation experiment
with fabrics hanging 1.5 m above ground likely underestimates chemical accumulation by
clothing. In reality, when we wear clothing it comes in contact with surfaces upon which SVOC-
contaminated dust can accumulate and direct chemical transfer could occur from a product to
fabric (e.g., Allen et al., 2008; Gallen et al., 2014; Abbasi et al., 2016). We did not investigate
chemical release during laundering associated with microfibres or microplastics. Browne et al.
(2011) reported the release of >1900 fibres per wash from single garment during laundering
where microfibers are known to contain sorbed chemicals (e.g., Teuten et al., 2007, 2009). We
also did not consider the role played by the chemistry of laundry soaps and detergents on
chemical release. Finally, we did not investigate the role of water temperature during laundering
that could affect the partitioning of accumulated chemicals in fabric-laundry water system, which
is analogous to temperature dependence of KOW and water solubility. Greater release would be
expected at warmer water temperatures than at room temperature (~25oC) tested here.
Uncertainties in the study included those introduced by inconsistencies and human errors that
occurred during manual washing and liquid-liquid extraction, such as squeezing laundry water
out of the fabrics or shaking intensity of fabrics and laundry water samples while laundering and
extraction, respectively. The use of a single dryer and collection of single lint sample for each of
109
cotton and polyester limits the conclusions drawn regarding fabric drying. Chemical release in
ventilated air from the dryer was also not considered.
5.6 Conclusions
Over 30 days, cotton and polyester deployed in an office accumulated concentrations of
∑5phthalates of 3300 and 1730, ∑10HFRs of 65 and 77, and ∑8OPEs of 830 and 290 ng/dm2,
respectively. Concentrations of OPEs and low molecular weight phthalates, normalized to planar
surface area, were greater in cotton than polyester and similar for HFRs and high molecular
weight phthalates. Cotton accumulated equal or lower concentrations relative to polyester when
normalized to BET-SSA. From this we hypothesize that cotton, with its large BET-surface area,
‘diluted’ chemical concentrations relative to polyester or that polyester has a higher capacity for
non-polar chemicals. The results also showed that the differences between chemical
concentrations accumulated by cotton versus polyester, on a planar and BET-SSA basis, were
significantly and inversely correlated with KOW. This is consistent with previous studies that
showed greater sorption of polar compounds to polar fabrics such as cotton and the hypothesis of
chemical dissolution into a surface water film on polar fabrics. Chemical release from cotton and
polyester to laundry water was also a function of KOW, with >80% release of OPEs, especially
polarizable compounds with aliphatic chains such as TCEP and TCPPs. Release of OPEs with
aromatic structures (TPhP and EHDPP) was <50%, lower than the 50–80% release of low
molecular weight phthalates. Release of high molecular weight phthalates and HFRs was 10–
35%. Our results support the hypothesis of Schreder and La Guardia (2014) that clothing acts an
efficient conveyer of soluble SVOCs present indoors to outdoors via laundering. This indoor-to-
outdoor pathway via laundering is accentuated for polar compounds such as OPEs and polar
cotton, which tends to accumulate more than non-polar polyester on a planar surface area basis.
Clothes drying could also contribute to the release of chemicals accumulated from air and
released from electric dryers. The significance of these results for dermal uptake rests on whether
clothing acts as a barrier for uptake of soluble chemicals, such as OPEs, that are released during
laundering, or as a source of chemicals, such as HFRs, that accumulate over time.
110
Acknowledgements
We thank Prof. Nathalie Tufenkji and David Morris (McGill University, Canada) for BET-SSA
measurements. Research funding was provided by the Natural Sciences and Engineering
Research Council of Canada (NSERC) and the Allergy, Genes and Environment Network
(AllerGen NCE) to MD and University of Toronto Scarborough to AS.
111
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Chapter 6: Conclusion
6.1 Summary of the research
The thesis contributes to the overall goal of improving the understanding of the accumulation of
SVOCs to fabrics when exposed to ambient air and SOVC release as a result of laundering.
SVOCs are present indoors and their accumulation by indoor media such as furniture, dust and
window films has been investigated in literature (Butt et al., 2004; Stapleton et al., 2012; Abbasi
et al., 2016 inter alia). In terms of human exposure, the pathways of direct inhalation and
ingestion have been studied most extensively (Jones-Otazo et al., 2005; Shi and Zhao, 2014;
Schreder et al., 2015; Ionas et al., 2016), with increasing attention being devoted to dermal
exposure (e.g., Weschler and Nazaroff, 2012; Abdallah et al., 2015, 2016; Hoffman and
Stapleton, 2015; Weschler et al., 2015). The role of clothing in enhancing or impeding human
exposure has received relatively little attention (e.g., Morrison et al., 2016). To understand the
role played by clothing in terms of human exposure, I needed to understand the propensity of
clothing to accumulate and release of SVOCs. I hypothesize that clothing accumulates SVOCs
from ambient air by gas-phase sorption and particle-phase accumulation, thereby affecting
chemical fate and exposure. The sorbed chemicals may be released to waste water while
laundering, thereby providing a transfer pathway of SVOCs from indoors to outdoors and thus
influencing ecosystem exposure. Accumulation and release are hypothesized to be driven by the
physical-chemical properties of SVOCs and fabrics. Testing these hypotheses involved
characterizing accumulation and release as a function of the physical-chemical properties of
fabrics as well as SVOCs, understanding if uptake kinetics including reaching equilibrium
between air and fabrics, was likely to be achieved, and if laundering reduces the chemical burden
of clothing. Cotton, polyester and rayon served as test fabrics to achieve this goal. The SVOCs of
interest were phthalates and halogenated and organophosphate flame retardants (HFRs and
OPEs, respectively). These compounds were chosen because of their well-documented presence
indoors (e.g., Dodson et al., 2012; Bradman et al., 2014) and because of their toxicological
concern (Eskenazi et al., 2013; Lyche et al., 2015; Zhu et al., 2015).
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To test these hypotheses, measurements and analytical methods were needed. Limited research
had investigated uptake of SVOCs present indoor to sampling media when the Doctoral research
was planned. Therefore, indoor air passive sampling methods were first evaluated, using two
well characterized passive air samplers (PAS). Results from Chapter 2 characterized the uptake
of phthalates and brominated flame retardants (BFRs) indoors by polyurethane foam (PUF) and
sorbent impregnated PUF (SIPs) using fully and partially sheltered housings. This was the first
study to report on phthalate uptake rates by indoor PAS. Based on calibration against gas- and
particle-phase concentrations measured using an active low-volume air sampler, I recommended
generic sampling rates of 3.5±0.9 and 1.0±0.4 m3/day for partially and fully sheltered housing,
respectively. This was recommended for gas-phase phthalates and BFRs as well as particle-phase
DEHP (the latter for the partially sheltered PAS). Results confirmed similar accumulation of gas-
and particle-phase chemicals by passive air sampling media. For phthalates, partially sheltered
SIPs were recommended since phthalates sorbed to PUF showed an ambiguous uptake pattern
over time. Further, I recommended the use of partially sheltered PAS indoors and a deployment
period of one month. The sampling rate for the partially sheltered PUF and SIP of 3.5±0.9
m3/day was similar to that reported for fully sheltered PAS deployed outdoors. These results
were consistent with the interpretation that uptake was air-side controlled and independent of the
sorbent used. The results also indicated that PAS ‘sees’ same amount of air while deployed
outdoors in a fully sheltered housing versus a partially sheltered housing used indoors. Outdoors,
fully sheltered housing minimizes the effect of variable wind velocities and other environmental
factors on chemical uptake, for which it was developed. Indoors, a partially sheltered housing
maximizes chemical uptake where air flow rates are low and hence sampling of more air volume
is needed.
My next step was to determine sorption behaviour of fabrics. I began with characterizing
sorption of gas-phase PBDE to cotton and polyester fabrics under controlled chamber conditions.
The goal of this study (Chapter 3) was to investigate the role of physical-chemical properties of
fabrics as well as SVOCs in their sorption. Cotton and polyester were chosen for investigation as
they differ in both chemical and physical properties. Scanning electron microscopic (SEM)
images and BET specific surface area (BET-SSA) analysis showed differences in their physical
structures; NMR analysis showed the richness of hexose- and aromatic-carbon in cotton and
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polyester, respectively. Hence polyester was expected to have higher affinity towards
hydrophobic PBDEs because of the aromatic moiety. Greater sorption of lower molecular weight
PBDEs was consistently measured due to higher chamber air concentrations that were caused by
greater volatilization from a PBDE-impregnated filter placed in the chamber as a source. Both
fabrics showed statistically similar sorption per unit planar surface area. When normalized to per
unit mass and BET-SSA, polyester showed statistically higher sorption compared to cotton,
which could be due to dilution of chemical mass by cotton because of its greater density and
BET-SSA or greater affinity of PBDEs to polyester than cotton. Results from this experiment did
not allow us to distinguish between these two hypotheses. The results from this study were
discussed in terms of the importance of fabrics (e.g., clothing, draperies, and upholstery) as a
sink for PBDEs and other non-polar compounds indoors. The results were also discussed in the
context of dermal exposure.
I then moved to investigate the accumulation of SVOCs by fabrics under ambient indoor
conditions (Chapter 4). Here, the analytes were phthalates and HFRs, and cotton and rayon were
used as test fabrics. Both fabrics are comprised of cellulose with glucose monomers. However
rayon, which is synthetically spun cellulose, had four times lower BET-SSA than cotton used in
this study. Both gas- and particle-phase accumulation of phthalates and HFRs was seen. Being
chemically similar and having similar density, cotton and rayon showed statistically similar
accumulation of SVOCs in bedrooms, living rooms and offices when normalized to planar
surface area. Offices had significantly higher concentration of HFRs than homes, indicating
potentially greater exposure to these chemicals from office environments, which has been shown
Watkins et al. (2011). When the results were normalized to BET-SSA, rayon had significantly
greater accumulation compared to cotton, consistent with the hypothesis of dilution of mass
accumulated by cotton. Both cotton and rayon showed linear uptake at the rate of 0.4–0.9 m3 air
equivalent/day.dm2 fabric and mass transfer coefficients of 1.5–3.8 m/h for eight HFRs during a
56 day deployment. Again, these results, which are similar to uptake rates and mass transfer
coefficients of PAS media indoors, suggested air-side controlled uptake. These rates imply that 2
m2 of typical clothing worn by a person would sequester chemical in the equivalent of 100 m3 of
air per day. The estimated sampling rates and mass transfer coefficients represent the lower
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limits because of stationary experiment conditions. In reality, uptake of these chemicals by
clothing while worn will constantly change with the movement of a person.
Since chemical uptake was still in the linear phase after 56 days, fabric-air distribution
coefficients, K’fabric-air, were calculated. These values were similar, regardless of fabric or a
chemical’s KOA. The values of log K’fabric-air of 6.5–7.1 were less than equilibrium partition
coefficients, log Kfabric-air, estimated using pp-LFER of Holmgren et al. (2012) of 9–12 and the
COSMO-RS model of 7–9 for HFRs ranging in log KOA from 9–11.5. Parameters and descriptor
values used in pp-LFER and COSMO-RS models were derived for the pure form of cellulose and
hence are considered to be a reasonable representation of cotton and rayon fabrics. Based on the
Kfabric-air estimated using the COSMO-RS model, the time to reach 95% of the equilibrium value
was estimated as >10 years for PBDEs. This result shows that fabrics can be an important sink of
these chemicals indoors.
Finally, Chapter 5 again investigated SVOC accumulation from indoor air as well as release to
laundry water and the role played by clothes dryers. This experiment used cotton and polyester
of similar density. The results showed distinct patterns of SVOC accumulation by fabrics and
release to laundry water based on physical-chemical properties of the accumulated chemicals.
First, non-polar HFRs and phthalates showed statistically similar accumulation by cotton and
polyester but polar OPEs showed greater affinity and hence accumulation by cotton when
concentrations were normalized to planar surface area. A significant relationship was found
between the difference in sorption to cotton versus polyester and octanol-water partition
coefficient, KOW, and water solubility. OPE results were contrary to the presumed air-side
controlled sorption of chemicals hypothesized in Chapter 4. Rather, these results are consistent
with reports in the literature of greater sorption of polar compounds to polar fabrics (e.g., Piadé
et al., 1999; Petrick et al., 2010). More water soluble OPEs showed >80% release of accumulated
mass to laundry water, whereas hydrophobic HFRs showed <10% release of the accumulated
mass. Phthalates showed intermediate results with ≥ 50% of lower molecular weight phthalates
released into laundry water while ≥ 65% of higher molecular weight phthalates remained on
fabrics. The release behaviour from fabric to laundry water was a function of KOW and water
solubility but not the chemistry of the fabric. Release to laundry water was also independent of
whether the chemical was in the gas or particle phase in indoor air. The results from a single
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dryer investigation revealed that the dryer acted as a significant source of DBDPE to laundered
fabrics, which was not detected otherwise in the fabrics exposed indoors. The role of dryers in
the transfer of flame retardants to fabrics needs further investigation.
The results from Chapter 5 have several implications. First, the results support the view that our
clothing acts as a collector and transporter of these chemicals from indoors to outdoors, as
hypothesized by Schreder and La Guardia (2014). It also provides an explanation for greater
levels of OPEs in WWTPs and receiving waters given that OPEs are nearly entirely released to
water during laundering. Thus, clothing acts as a conveyer of OPEs from indoors to outdoors,
with estimated loadings of 500 mg of OPEs per laundry load to waste water. Contrary to OPEs,
laundered clothing retained ≥ 90% HFRs and high molecular weight phthalates which indicates
clothing's ability accumulate SVOCs and tendency to act as a continuous sink of these chemicals
with the potential to enhance exposure. If we follow the journey of the chemicals released in
laundry water such as OPEs to outdoors, they end up reaching our water bodies, thus causing
exposure at the ecosystem level.
6.2 Major findings
Major findings of the accumulation and release behaviour of SVOCs by cotton, rayon and
polyester fabrics observed in the experiments in this thesis are summarized in Table 6.1.
Polyester, cotton and rayon accumulated similar concentrations of non-polar HFRs on per
unit planar surface area basis. These results, and the similarity of uptake rates to indoor
passive sampling media, suggest air-side controlled update, independent of the chemical or
sorbent fabric.
The sorption of non-polar SVOCs to fabrics increased as a function of vapour pressure and
was inversely related to KOA.
Distribution coefficients between fabrics and air of non-polar SVOCs were estimated at 6.5-
7.1 (log values) after 56 days. Estimated equilibrium partition coefficients were 8.4-12 (log
values). Thus, fabrics have a very high sorptive capacity indicating that they will be a
significant sink for indoor SVOCs.
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Cotton accumulated more polar OPEs and lower molecular weight phthalates than polyester
on a planar area basis but accumulated less non-polar HFRs, OPEs and phthalates when
considering BET-SSA.
Three hypotheses were presented to account for these differences: (i) greater affinity of polar
SVOCs for polar fabrics and non-polar SVOCs for non-polar polyester, (ii) dissolution of polar
SVOCs in a surface water film accumulated by cotton given its polarity, and (iii) chemical
dilution by cotton due to its 4–10 times greater BET-SSA than polyester and rayon.
The major findings from this research regarding chemical release were as follows:
SVOCs accumulated by cotton and polyester showed similar percentages of release to
laundry water.
Release of more water soluble OPEs was >80% whereas, minimal release of HFRs occurred
during laundering. Phthalates showed mixed release based on chemical molecular weight
and solubility.
SVOC release from fabrics to laundry water was consistent with KOW and water solubility.
Release also appeared to be a function of chemical polarizability, although more data is
needed to test this hypothesis
SVOC release to laundry water was not related to the extent of gas versus particle-sorption.
These results have implications for the fate of SVOCs and raise several questions regarding
dermal uptake of SVOCs accumulated by fabrics.
Fate of chemicals present indoors
• Clothing acts as a sink of polar and non-polar SVOCs present indoors. This was
exemplified by estimating that 2 m2 of clothing typically worn by a person could
sequester chemicals present in 100 m3 of equivalent air per day and >10 years would
be required to reach equilibrium.
• Clothing also acts as a conduit for polar SVOCs from indoors to outdoors due to
accumulation followed by efficient release during laundry. In contrast, clothing is
hypothesized to act as a continuous sink for non-polar SVOCs due to their negligible
release during laundering. It is noted that this conclusion is limited to clothing that
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accumulates SVOCs from gas- and particle-phase compounds in air only and not dust
from surfaces.
The following questions regarding human exposure to SVOCs have emerged from this
research:
• Can dermal exposure be enhanced by sorption of SVOCs from air ambient air and
then release due to higher temperatures in the clothing-skin air pocket?
• Although polar SVOCs are efficiently released from fabrics when laundered, in
which case clothing should provide a barrier for uptake (e.g, Morrison et al., 2016),
could dermal uptake be enhanced by dissolution into sweat?
• Can clothing enhance exposure to non-polar SVOCs that are not released by
laundering, particularly as the chemicals sorb to skin oils?
Table 6.1. Summary of findings of fabric experiments reported in Chapters 3, 4 and 5.
Polyester Cotton Rayon
OPES
Sorption - Planar - + (1.5–7×) n/a
Sorption - BET ~ or + (3–9×) ~ or - n/a
Wash 100% 100% n/a
HFRs
Sorption - Planar ~ ~ ~
Sorption - BET + (Chamber 20–50×) (Indoor 6–12×) - + (3–10×)
Wash <10% <10% n/a
Phthalates
Sorption - Planar LMW - HMW ~
LMW + (5–9×) HMW ~ ~
Sorption - BET LMW ~ HMW + (6–9×)
LMW ~ HMW - n/a
Wash LMW >50% HMW <35%
LMW >80% HMW<35% n/a
Note: + indicates greater, - indicates lower and ~ indicates statistically similar concentrations.
LMW phthalates: DiBP and DnBP; HMW phthalates: BzBP, DEHP and DiNP. n/a: not
applicable.
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6.3 Recommendations for future work
Along with providing new insights into SVOC accumulation by and release from fabrics, this
thesis has raised areas for future investigation.
I published uptake rates of predominantly gas-phase chemicals using two PAS (Ch 2). Due
to lack of detection of more particle-phase chemicals, the data were not reported. Uptake
kinetics of particle-bound chemicals indoors should be investigated.
In chamber and ambient indoor experiments (Ch 3 and 4), accumulation of SVOCs to fabrics
was in the linear uptake phase and had not attained equilibrium. The findings here show the
role of physical and chemical properties of fabrics in SVOC accumulation. Additional
experimentation under controlled conditions, such as longer duration of chamber
experiments and manipulation of relative humidity, and mechanistic modeling are needed to
elucidate the sorptive capacity and affinity of different types of fabrics under linear uptake
and equilibrium conditions for a broader range of chemicals. The recommendation for
conducting experiments under controlled conditions is presented because of the very long
time required for hydrophobic chemicals to attain equilibrium under ambient conditions.
In chapter 3, I confirmed absence and abundance of aromaticity in cotton and polyester
fabrics, respectively, that could affect sorption. The literature has shown that aromaticity
should not be taken as a sole criterion to determine sorption (Simpson et al., 2003; Wang
and Xing, 2007). Glassy and rubbery states of the sorbent can also determine the availability
of moieties for sorption. Hence, I recommend investigating the glassy and rubbery state of
various fabrics to thoroughly understand their sorption behaviour.
Our experiments in chapters 3, 4 and 5 did not assess the effect of relative humidity on the
accumulation of SVOCs by fabrics. Relative humidity is known to alter the physical-
chemical conditions of fabrics such as the swelling of hygroscopic fibres and water
molecules filling sorption sites or even acting as a medium to dissolve soluble chemicals
such as OPEs. As such, role of relative humidity in enhancing or hindering sorption in
natural versus a range of synthetic fabrics should be investigated.
Similarly to the point raised above, I hypothesized air-side controlled uptake based on
similarities in sorption of SVOCs to fabrics on planar surface area basis, assuming
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equilibrium had not been reached. However, the significant relationship between KOW and
the difference in the accumulation of OPEs by cotton versus polyester indicates the
possibility of OPEs dissolution into surface water film that could develop on polar fabrics.
As such, it raises the question of role of the physical-chemical properties of fabrics in
chemical accumulation for highly soluble OPEs, which is contrary to air-side control uptake.
In chapter 5, I found only a single dryer as a large source of the flame retardant DBDPE for
laundered fabrics. This is a source of concern regarding exposure to flame retardants from
dryers, such as for children who could be zipped up head-to-toe in DBDPE contaminated
sleepwear. In this case, children could be subject to exposure by dermal transfer or ingestion
by chewing on contaminated, dried fabrics. The preliminary results from this study can be
used to devise a detailed investigation to assess the role of dryers in contaminating ‘clean’
clothing and also if the outgoing dryer air carries a substantial amount of flame retardants
outdoors, similarly to indoor air ventilation.
I tested cotton, rayon and polyester in our experiments; however these studies should be
extended to broader range of fabrics such as nylon, fleece and spandex that vary in their
physical and chemical properties. Also, I used untreated fabrics. Studies are required to
investigate the fate of chemicals intentionally added to fabrics and if these chemicals, such
as perfluorinated compounds, change the accumulation behaviour of fabrics for other
SVOCs. Thus, it is recommended to also test treated fabrics for SVOC uptake and release.
I studied the partitioning of chemicals of interest in air-cloth-laundry system using
experimental methods (Ch 3, 4 and 5). Mechanistic modeling is suggested to further
investigate pathways that transfer chemical from indoors to outdoors through this system.
Also, implications for dermal transfer, considering variables such as temperature and relative
humidity, and assessing various classes of chemicals for which it could be an important
exposure route, deserve further attention.
Numerous students have shown the protective effect of clothing in occupational settings
(Macfarlane et al., 2013; Moore et al., 2014 inter alia). As noted above, the results presented
here raise numerous questions regarding the role of clothing for dermal uptake under non-
occupational settings and which could also inform occupational settings. A next step would
be to conduct experiments to answer these questions by investigating air-cloth-skin transfer
of SVOCs, similarly to those done by Morrison et al. (2016). These studies should assess a
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variety of fabrics, a variety of polar and non-polar SVOCs in gas and particle phases, length
of time fabric is worn, and length of time fabrics are exposed to ambient indoor
concentrations of SVOCs.
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Appendices
Appendix 1: Supporting Information for chapter 2
Calibration of two passive air samplers for monitoring phthalates and
brominated flame-retardants in indoor air.
Compounds of Interest:
Table A1.1. Details of compounds investigated in this study.
Abbreviation Compound name CAS no. Molecular weight
New flame-retardants (NFRs) ATE Tribromophenyl allyl ether 3278-89-5 370 PBBz Pentabromobenzene 608-90-2 472 PBT Pentabromotoluene 87-83-2 486 PBEB Pentabromoetheyl benzene 85-22-3 501 HBB Hexabromobenzene 87-82-1 551 EH-TBB Ethylhexyl-tetrabromobenzene 183658-27-7 550 BEH-TEBP Bis(2-ethlyhexyl) tetrabromophthalate 26040-51-7 706 s-DP Dechlorane plus
13560-89-9 653
a-DP Dechlorane plus OBIND Brominated trimethylphenyl indane 155613-93-7 867 DBDPE Decabromodiphenylethane 84852-53-9 971
Polybrominated diphenyl ether (PBDEs) BDE-17 2,2',4-Tribromodiphenyl ether 147217-75-2 407 BDE-28 2,4,4'-Tribromodiphenyl ether 41318-75-6 407 BDE-71 2,3',4',6-Tetrabromodiphenyl ether 189084-62-6 486 BDE-47 2,2',4,4'-Tetrabromodiphenyl ether 5436-43-1 486 BDE-66 2,3',4,4'-Tetrabromodiphenyl ether 189084-61-5 486 BDE-100 2,2',4,4',6-Pentabromodiphenyl ether 189084-64-8 565 BDE-99 2,2',4,4',5-Pentabromodiphenyl ether 60348-60-9 565 BDE-85 2,2',3,4,4'-Pentabromodiphenyl ether 182346-21-0 565 BDE-154 2,2',4,4',5,6'-Hexabromodiphenyl ether 207122-15-4 644 BDE-153 2,2',4,4',5,5'-Hexabromodiphenyl ether 68631-49-2 644 BDE-138 2,2',3,4,4',5'-Hexabromodiphenyl ether 182677-30-1 644 BDE-183 2,2',3,4,4',5',6-Heptabromodiphenyl ether 207122-16-5 722 BDE-190 2,2',3',4,4',5',6-Heptabromodiphenyl ether 83992-70-5 722
130
BDE-209 Decabromodiphenyl ether 1163-19-5 959 Phthalates
DEP Diethyl Phthalate 84-66-2 222 DiBP Di isobutyl phthalate 84-69-5 278 DnBP Di-n-butyl phthalate 84-74-2 278
BzBP Benzyl butyl phthalate 85-68-7 312 DEHP Di (2-ethylhexyl) phthalate 117-81-7 391 DiNP Di isononyl phhalate 68515-48-0 419
Housing designs:
Figure A1.1. Diagrammatic representation of double bowl (top left) fully sheltered, single bowl (top right) partially sheltered housing and tripod stand (bottom) partially sheltered housing. Note: Dotted lines indicate movement of air within the housing.
131
Standards: (Accustandard, USA and Wellington laboratories, Canada): DEP-d4 was used as
surrogate standard for phthalates and mass-labelled PBBZ, HBB and F-BDE 100, F-BDE 154, F-
BDE 208 (fluorinated BDEs) were used as surrogate standards for flame-retardants
(Accustandard, USA and Wellington laboratories, Canada). For phthalates, recoveries were
between 60-100% whereas recoveries for flame-retardants were 70-130%. The data were
quantified using an internal standard Fluoranthene-d10 and BDE-118 for phthalates and flame-
retardants, respectively, which were added to final volume of the extract before injection onto the
GC-MS. Quantification was done using 6-point calibration curve for GC-MS/EI analysis of
phthalates and 5-point calibration curve for GC-MS/NCI analysis of NFRs and PBDEs.
Laboratory and field blanks were extracted and analysed (spiked with surrogate standards and
internal standard) in every batch of 10 samples.
Surrogate standards:
• NFRs (13C12-labelled, 20 ng each): m-PBBz and m-HBB
PBDEs (Fluorinated BDEs, 20 ng each): F-BDE 100; F-BDE 154 and F-BDE 207
• Phthalates (deuterated, 100 ng): DEP-d4
Internal standards:
• NFRs/PBDEs (50 ng): BDE-118
• Phthalates (150 ng): Flouranthene-d10
Extraction and analysis: SIPs, PUFs, PUF plugs, XAD resin and filters were extracted by
accelerated solvent extraction on Dionex ASE 350 using hexane and DCM (1:1,v/v) solvents at
following operating conditions: temperature: 80°C, pressure: 1500 psi, heat time: 5 min, static
time: 4 min, flush volume: 60%, purge time: 60 s, and static cycles: 3.
Before usage, stainless steel bodies of ASE cells were baked at 250°C and rinsed thoroughly
along with cell caps with three solvents (Hexane, DCM and Methanol). Two filters (cellulose
and glass fibre filters) were place at the bottom of the cell. For clean-up of the extract, a layer of
5g pre-cleaned alumina (80-200 mesh, Fischer Scientific) and 10 g anhydrous sodium sulfate
132
(Fischer Scientific) was added to each ASE cell before adding the sample (Figure A1.2). The
extract was then reduced to 0.1 mL under gentle stream of nitrogen in a Turbo-vap followed by
reconstituting the final volume to 0.5 ml in GC vials using isooctane. Samples were analysed
using Agilent 6890N Gas chromatograph coupled with Agilent 5975 inert mass-spectrometer
(GC-MS). Phthalates analysis was performed using 30 m DB-5 MS column (Agilent
technologies, 0.25 mm i.d. and 0.25 µm film thickness) on EI source at following oven
temperature program: initial at 75°C hold for 3 mins, 10°C min-1 to 320° C and hold for 3 min.
PBDEs and NFRs analysis was performed using 15 m DB-5 MS column (Agilent technologies,
0.25 mm i.d. and 0.25 µm film thickness) on NCI source at following oven temperature program:
initial at 100° C hold for 1.5 min, 12°C min-1 to 250°C, then 60 C min-1 to 290°C, hold for 3 min
and finally 40°C min-1 to 320°C, hold for 11 min.
Figure A1.2: In-cell (ASE) extraction and clean up configuration.
QA/QC: Analytical methods for flame-retardants and phthalates were validated for their
reproducibility using certified reference material (NIST SRM-2585-organic contaminants in
house dust). Five CRM/SRM replicates were included in sample analysis and the measured
values for PBDEs were compared to certified values of SRM. Except BDE-209, PBDE
congeners showed good reproducibility with relative standard deviation (RSD) of individual
congener ranging from 2 to 12% as compared to RSD range of 1-13% for certified values. The
analysis also showed good accuracy with average RSD of 7% between measured and certified
133
values (Figure A1.3). Since SRM does not have reported certified values of phthalates, the
measured values were compared to the SRM phthalates concentrations reported by Bergh et al.
(2012). Measured phthalates concentrations showed good reproducibility with RSD of 3-10%
compared to the RSD range of 2-5% of Bergh et al. (2012) (Figure A1.4). Phthalates also showed
good accuracy with average RSD of 13% between measured and reported values. NIST SRM has
neither certified nor reported values of NFRs, thus the method was validated by assessing
recoveries reproducibility of the spiked samples only (Figure A1.5). Except for OBIND and
DBDBE, spike recoveries of NFRs were >75% and reproducibility with RSD ranging between 7-
15%. The high recovery of PBEB was due to contamination issues observed in laboratory blanks;
the reason for high recoveries of TDCiPP and TBB was unknown. Hence, laboratory and field
blanks were processed along with real samples to monitor for contamination and blank
corrections were applied.
Detection frequencies of each compound are given in Table A1.2. Data for NFRs ATE, HBB,
EH-TBB, BEH-TEBP, DP, OBIND and DBDPE were discarded either due to very low detection
(comparable to their blank levels) or inconsistent accumulation by AAS and/or and PAS. Among
PBDEs, although BDE-71, -85, -154, -138, and -183 had up to 100% detection in either AAS or
PAS, however their concentrations were too low to show clear uptake patterns and accumulation
on AAS and PAS. Laboratory contamination was observed for PBEB and DiNP; as such, results
for these compounds were not included for further discussion. All samples were blank corrected
using the following criteria:
• Blank concentration < 5% of sample concentrations, no correction applied.
• 5% < blank concentration < 35% of sample concentration, blank correction applied.
• Blank concentration > 35% of sample concentration, sample results discarded.
The new in-cell extraction and clean-up procedure produced laboratory blanks that were
consistently low (<35% of sample), particularly for phthalates. DEP, which is frequently
elevated in blanks, had blank concentrations ≤ 10% and 10-35% of the sample values for 50%
and 35% of AAS and PAS samples, respectively. DnBP and BzBP had blank concentrations ≤
10% of the sample values for 70% and 67%, of the total samples, respectively. For DEHP, 33%
134
of samples had blank concentrations ≤ 10% and 33% had blank concentrations between 10-35%
of sample values. The remaining percentage of samples was discarded due to low detection.
Figure A1.3. Comparison of measured and certified PBDE values of NIST-SRM 2585 (error bars indicate standard deviation).
Figure A1.4. NIST-SRM 2585 phthalate concentration measured here and reported by Bergh et al. (2012) (error bars indicate standard deviation). *value not reported.
1
10
100
1000
10000 C
once
ntra
tion
(ng/
g)
Congener
Measured values
Certified values
1
10
100
1000
DEP DiBP DnBP BzBP DEHP DiNP*
Con
cent
ratio
n (µ
g/g)
Phthalates
Measured values
Reported values (Bergh et al.,2012)
135
Figure A1.5. Average spike recoveries of NFRs (dotted line indicate 100% recovery; error bars indicate standard deviation).
Table A1.2. Instrument detection limits (IDL) and detection frequencies of the studied compounds active and passive air samplers (AAS, PAS).
Compound IDL (pg)
or (ng)
Detection frequencies (%)
AAS (bulk) PAS
Partially sheltered Fully sheltered ATE 1.9 100 29 14 PBBz 0.8 100 100 100 PBT 1.4 100 100 100 PBEB 1.1 14 100 0 HBB 0.9 -- 71 14 EH-TBB 15 71 86 14 BEH-TEBP 15 -- 100 -- s-DP 9.3 -- -- -- a-DP 9.2 -- -- -- OBIND 10 29 14 -- DBDPE 34 14 29 -- BDE-17 0.5 100 100 100 BDE-28 3.2 100 100 100 BDE-71 4.5 29 86 14 BDE-47 4.6 100 100 100 BDE-66 3.2 100 100 100 BDE-100 5.0 100 100 100 BDE-99 6.8 100 100 100
0% 25% 50% 75%
100% 125% 150% 175% 200% 225%
Ave
rage
rec
over
ies
136
BDE-85 3.2 57 100 100 BDE-154 5.3 100 100 100 BDE-153 8.5 100 100 100 BDE-138 6.6 100 71 29 BDE-183 24 100 86 14 BDE-190 12 -- 14 -- BDE-209 4.1 43 100 43 DEP* 0.04 100 100 100 DiBP* 0.04 100 100 80 DnBP* 0.03 100 100 80 BzBP* 0.06 100 80 -- DEHP* 0.07 100 80 -- DiNP* 0.70 100 -- -- -- Values discarded due to detection problems
* IDL= ng
Theory: The detailed theory of gas-phase uptake by PAS has been explained by Shoeib and
Harner (2002) and Bartkow et al. (2005) using two-film diffusion model (Lewis and Whitman,
1924) assuming a uniform distribution of chemical within PAS media. Briefly, the movement of
gas-phase chemicals from air to sampling medium is driven by the concentration gradient
between air and the sampling medium as described in following equation:
𝑉𝑆𝑑𝐶𝑆𝑑𝑡
= 𝑘𝐴AS �CA −CS𝐾SA
�..........................................(A1.1)
where VS is the volume of sampler (cm3), CS and CA is concentration of compound (pg/m3) in the
sampler and air respectively , kA is air-side mass transfer coefficient, MTC (cm/s) which is the
inverse of the resistance posed by air-side boundary layer and is assumed to be equivalent to
overall mass transfer coefficient for non-polar compounds with high octanol-air partition
coefficient (KOA), AS is surface area is sampler (cm2), KSA is sampler/air partition coefficient that
can be determined from KOA (Shoeib and Harner, 2002). For SVOCs, the term CS / KSA is very
small when the sampler is in linear uptake phase with a low concentration in the sampler and
thus uptake is mainly driven by air-side mass transfer rate i.e. kO α kA (Shoeib and Harner, 2002;
Wania et al., 2003; Bartkow et al., 2005).
137
However, Zhang et al. (2011) and Zhang and Wania (2012) determined through experimental
evidence and modelling that SVOC concentrations are non-uniformly distributed in PAS media,
which is contradictory to the assumptions of current passive sampling theory. Their study
revealed that apart from chemical diffusion across stagnant air boundary layer, diffusion within
macro-pores and reversible sorption between air in the pore space and PAS media are also
important aspects of chemical mass transfer processes in passive sampling (Zhang and Wania,
2012). This finding is contrary to the assumption that mass transfer is air-side controlled only
(i.e. kO = kA). However, due to lack of quantitative information such as diffusion length or
sorption rate constant, a complete understanding of the role of PAS-side kinetic resistance and
application of their uptake model is limited (Zhang et al., 2011; Zhang and Wania, 2012).
Therefore, the current theory of passive sampling is used here with modification by including
particle phase to total ambient air concentrations for derivation of sampling rates.
The sampling rate of a PAS can be determined from bulk air concentrations derived from time
integrated active sampling and mass accumulated on co-deployed passive air samplers. The
equivalent air volume (𝑉𝑒𝑞) in m3 is calculated to determine the uptake rate using the following
equation (derived from equation A1.1):
𝑉𝑒𝑞 = 𝑀𝐶𝐴
............................................................(A1.2)
where, M is the mass of compound accumulated in the PAS (ng) and CA is the running average
of ambient bulk air concentration (ng/m3) measured with, for example, a low-volume active air
sampler over sampling period. The slope of the line of best fit between 𝑉𝑒𝑞 and deployment time
(days) provides the sampling rate, R m3/day (i.e. 𝑉𝑒𝑞= RΔt). According to Shoeib and Harner
(2002), uptake of PAS can be described in three phase: linear, curvilinear and equillibrium
partitioning phases. The sampling rate is derived from the linear uptake phase of the compound
as in this stage the rate of loss of compound from passive sampler is considered insignificant
relative to the rate of uptake (Shoeib and Harner, 2002; Wania et al., 2003).
138
Results:
Figure A1.6. Average bulk (gas + particles) air concentrations of phthalates (ng/m3, black circles) and BFRs (pg/m3, blue diamonds) determined by low-volume active air sampling (AAS). Circles and diamonds indicate average concentrations and error bars indicate ± standard deviation.
Table A1.3. Comparison of phthalates air concentrations (Average ± SD, ng/m3) measured in this study and reported in literature. Gas-phase distribution (%) is given in parenthesis.
Phthalates This study Fromme et al. (2004), Germany
Rudel et al. (2003), US
Rudel et al. (2010), US
Average± SD Min Max Min Max Min Max Min Max
DEP 60 ±7.6 (98) 49 70 -- 1860 130 4300 110 2500
DnBP 85 ±14 (95) 64 101 -- 2453 52 1100 28 1100
BzBP 17 ±2.4 (67) 14 20 -- 75 <RL 480 -- 80
DEHP 46 ±10 (2) 32 58 -- 390 <RL 1000 -- 200
(--minimum concentrations not provided in the paper; <RL: below reporting limit)
1
10
100
1000 D
EP
DnB
P
BzBP
DEH
P
PBBZ
PBT
BDE-
17
BDE-
28
BDE-
47
BDE-
66
BDE-
100
BDE-
99
BDE-
153
Phthalates Flame retardants
Aver
age
air c
once
ntra
tion
(gas
+par
ticle
s)
Phth
alat
es=
ng/m
3 ; BF
Rs=
pg/
m3
139
Table A1.4. Comparison of actively measured BFRs air concentrations measured in this study (Average ± SD, pg/m3) and reported in literature. Gas-phase distribution (%) is given in parenthesis.
This study Zhang et al (2011),* Canada
Abdallah and Harrad (2010), UK
Bohlin et al (2014), Czech Republic
PBBz 5.1 ±2.6 (100)
PBT 7.0 ±1.4 (83) 12 ±4.4 (97)
BDE-17 23 ±19 (100) 27 (100)
BDE-28 65 ±9.5 (100) 55 (100) 2.5 ±0.5 (100)
BDE-47 809 ±102 (96) 712 (97) 46 ±8.8 (83) 3.0 ±0.9 (94)
BDE-66 14 ±4.0 (81) 9.4 (96)
BDE-100 45.0 ±8.0 (99) 33 (86) 6.7 ±4.1 (61) 0.3 ±0.1 (88)
BDE-99 111 ±20 (74) 83 (77) 37 ±11 (63) 0.9 ±0.4 (66)
BDE-153 22 ±16 (30) 6.0 (67) 7.9 ±4.1 (42)
BDE-183 ND 0.9 (0) 2.3 ±1.2 (17)
BDE-209 ND 66 ±15 (0)
*SD not reported; ND= Non detect
Table A1.5. Summary of linear regression analysis of comparison of compound profiles in PAS versus active air sampler (Bulk and gas phase).
Bulk Gas Phthalates
PS r2 0.62 0.47 slope 0.96 1.05
FS* r2 0.62 0.39 slope 0.63 0.88
BFR**
PS r2 0.94 0.96 slope 0.94 0.96
FS r2 0.96 0.90 slope 0.94 0.94
PS: partially sheltered; FS: fully sheltered *Only for DEP and DnBP **Excluding BDE-47 because of its very high concentration.
140
Table A1.6. Comparison of indoor sampling rates measured in this study and reported in the literature for Phthalates, PBDEs and NFRs.
Compounds Phthalates PBDEs NFRs
Sampling rates (m3/day)
This study 2.1-5.9 (PS) 0.8-1.2 (FS)
2.7-3.4 (PS) 0.6-1.1 (FS)
4.3 (PS) 1.7-1.9 (FS)
Bohlin et al. (2014) 0.9-2.9 (FS) 1.2-4.6 (FS)
Wilford et al., (2004) 2.5 (PS)
Hazrati and Harrad, (2007) 1.1-1.9 (FS)
Abdallah and Harrad, (2010)
0.6-1.5 (FS)
(PS: partially sheltered; FS: fully sheltered)
Table A1.7. Group specific sampling rates (m3/day) of SIPs and PUFs derived for phthalates and BFRs, respectively.
Compound Grouping criteria Sampling rate (m3/day) Phthalates
Partially sheltered SIP Fully sheltered SIP DEP Log KOA =7.6 2.1 0.8 DnBP Log KOA ≈ 8-9 4.7 1.2 BzBP DEHP Log KOA = 10.5 2.8 -
Brominated flame-retardants Partially sheltered PUF Fully sheltered PUF PBBZ 5-Br NFR 4.3
1.8 PBT BDE-17 3-Br BDE 3.3 0.9 BDE-28 BDE-47 4-Br BDE 2.8 0.7 BDE-66 BDE-100 5-Br BDE 3.1 1.1 BDE-99 BDE-153 6-Br BDE 0.6 -
Mass transfer coefficient (MTC): The air side mass transfer coefficient (kA, cm/s) represents
the velocity at which a compound is deposited on to PAS and it is equivalent to the overall mass
141
transfer of the compound (Shoeib and Harner, 2002). The MTC is calculated as kA= R/AreaPAS,
where AreaPAS is the area of PUF or SIP-PAS disk (360 cm2). Sampling rates, calculated using
bulk-phase air concentrations, were used for calculating MTC. Values of MTC ranged from 0.07
to 0.19 cm/sec for partially sheltered PAS (excluding 0.02 cm/s for BDE-153) and 0.02 to 0.06
cm/s for fully sheltered PAS (Figure A1.7), which is in good agreement with the range of 0.02-
0.06 cm/s reported by Hazrati and Harrad (2007) for PCBs and PBDEs for fully sheltered PUF-
PAS. Again, the effect of housing can be clearly seen from kA values as the partially sheltered
housing reduces the air side boundary resistance at the PUF-air interface or allowed for increased
particle deposition and hence increases mass transfer of the chemicals. Similar differences were
seen for PCBs (average MTC 0.03 cm/s) sampled by fully sheltered PUFs by Hazrati and Harrad
(2007) in comparison to the values reported by Shoeib and Harner (2002) for unsheltered PUFs
(average MTC 0.11 cm/s).
Figure A1.7. Air-side mass transfer coefficient (kA, cm/sec) calculated from (bulk) sampling rates of phthalates and BFRs.
0.00
0.02
0.04
0.06
0.08
0.10
0.12
0.14
0.16
0.18
0.20
DEP
DnB
P
BzBP
DEH
P
PBBZ
PBT
BDE-
17
BDE-
28
BDE-
47
BDE-
66
BDE-
100
BDE-
99
BDE-
153
SIPs PUFs
Air
-sid
e M
TC
(cm
/sec
)
Partially shletered
Fully sheltered
142
References Abdallah, M. A.-E., Harrad, S. 2010. Modification and calibration of a passive air sampler for
monitoring vapor and particulate phase brominated flame retardants in indoor air: application to car interiors. Environmental Science and Technology, 44(8), 3059–3065. doi:10.1021/es100146r
Bartkow, M. E., Booij, K., Kennedy, K. E., Müller, J. F., Hawker, D. W. 2005. Passive air sampling theory for semivolatile organic compounds. Chemosphere, 60(2), 170–176. doi:10.1016/j.chemosphere.2004.12.033
Bergh, C., Luongo, G., Wise, S., Ostman, C. 2012. Organophosphate and phthalate esters in standard reference material 2585 organic contaminants in house dust. Analytical and Bioanalytical Chemistry, 402(1), 51–59. doi:10.1007/s00216-011-5440-2
Bohlin, P., Audy, O., Skrdlíková, L., Kukučka, P., Vojta, S., Přibylová, P., Klánová, J. 2014. Evaluation and guidelines for using polyurethane foam (PUF) passive air samplers in double-dome chambers to assess semi-volatile organic compounds (SVOCs) in non-industrial indoor environments. Environmental Science. Processes and Impacts, 16(11), 2617–2626. doi:10.1039/c4em00305e
Fromme, H., Lahrz, T., Piloty, M., Gebhart, H., Oddoy, A.,Ruden, H. 2004. Occurrence of phthalates and musk fragrances in indoor air and dust from apartments and kindergartens in Berlin (Germany). Indoor Air, 14, 188–195. doi:10.1046/j.1600-0668.2003.00223.x
Hazrati, S., Harrad, S. 2007. Calibration of polyurethane foam (PUF) disk passive air samplers for quantitative measurement of polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs): factors influencing sampling rates. Chemosphere, 67(3), 448–455. doi:10.1016/j.chemosphere.2006.09.091
Lewis, W. K., Whitman, W. G. 1924. Principles of Gas Absorption. Industrial and Engineering Chemistry, 16(12), 1215–1220.
Rudel, R. a, Camann, D., Spengler, J. D., Korn, leo r, Brody, J. G. 2003. Phthalates, alkylphenols, pesticides, polybrominated diphenyl ethers, and other endocrine-disrupting compounds in indoor air and dust. Environmental Science and Technology, 37, 4543–4553. doi:10.1021/es0264596
Rudel, R. a, Dodson, R. E., Perovich, L. J., Morello-Frosch, R., Camann, D. E., Zuniga, M. M., Brody, J. G. 2010. Semivolatile endocrine-disrupting compounds in paired indoor and outdoor air in two northern California communities. Environmental Science and Technology, 44(17), 6583–6590. doi:10.1021/es100159c
Shoeib, M., Harner, T. 2002. Characterization and comparison of three passive air samplers for persistent organic pollutants. Environmental Science and Technology, 36(19), 4142–4151. doi:10.1021/es020635t
Wania, F., Shen, L., Lei, Y. 2003. Development and calibration of a resin-based passive sampling system for monitoring persistent organic pollutants in the atmosphere. Environmental Science and Technology, 37(7), 1352–1359.
Wilford, B. H., Harner, T., Zhu, J., Shoeib, M., Jones, K. C. 2004. Passive sampling survey of polybrominated diphenyl ether flame retardants in indoor and outdoor air in Ottawa, Canada: implications for sources and exposure. Environmental Science and Technology, 38(20), 5312–5318. doi:10.1021/es049260x
Zhang, X., Diamond, M. L., Robson, M., Harrad, S. 2011. Sources, emissions, and fate of polybrominated diphenyl ethers and polychlorinated biphenyls indoors in Toronto, Canada. Environmental Science and Technology, 45(8), 3268–3274. doi:10.1021/es102767g
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Zhang, X., Wania, F. 2012. Modeling the uptake of semivolatile organic compounds by passive air samplers: importance of mass transfer processes within the porous sampling media. Environmental Science and Technology, 46(17), 9563–9570. doi:10.1021/es302334r
144
Appendix 2: Supporting information for chapter 3
Characterizing the sorption of polybrominated diphenyl ethers (PBDEs) to
cotton and polyester fabrics under controlled conditions.
Introduction
Figure A2.1. Repeating cellulose unit of cotton (left) and polyester (right) structure (Mather and Wardman, 2011).
Methods
Figure A2.2. Diagram illustrating chamber used in sorption experiments. Chamber was developed and described by Rauert et al. (2015).
145
Extraction and analysis
ASE conditions: temperature 90°C, pressure 1500 psi, heat time 5 min, static time 4 min, flush
volume 50%, purge time 90 s, and static cycles 3. Hexane and DCM solvents (1:1, v/v) were
used for extraction.
LC-MS conditions: Analysis was conducted on a dual pump Shimadzu LC-20AB Prominence
liquid chromatograph (Shimadzu, Kyoto, Japan) coupled to Sciex API 2000 triple quadruple
mass spectrometer (Applied Biosystems, Foster City, CA) equipped with an APPI ion source was
used for separation and analysis. LC was also equipped with a SIL-20A autosampler and a DGU-
20A3 vacuum degasser and MS was operated in negative ion mode. Native PBDEs were
quantified using m/z 420.8/78.8, 500.8/78.8, 578.8/78.8, 658.6/78.8, 486.6/78.8 whereas, 13C-
labelled standards were determined based on m/z 432.4/78.8, 512.4/78.8, 590.6/78.8, and
494.7/78.8.
Results
Total recoveries: Figures A2.3-A2.5 show the recoveries of PBDEs from chamber experiments
conducted at room temperature, 40°C and 60°C temperature. The filter paper was spiked with
100 ng of each of BDE and placed in the chambers to act as a source followed by partition to
different chamber compartments, notably the chamber wall, cotton and polyester, PUF (air-flow
experiments only). Recoveries were highest at room temperature (~25°C) (although not
statistically significant) which is likely due to less volatilization of analytes from the filter paper
source at lower temperature and thus less PBDE loss in air while opening the chamber.
146
Figure A2.3. Sum of average recoveries of spiked PBDEs from filter paper, chamber walls, fabrics and PUF (with air flow only) obtained in chamber experiments without air flow (top) and with air flow (bottom). Error bars show maximum and minimum recovery.
0
20
40
60
80
100
BDE-47 BDE-85 BDE-99 BDE-100 BDE-153 BDE-154 BDE-183
Ave
rage
reco
veri
es (%
) 40° C (n=8) 60° C (n=6)
0
20
40
60
80
100
120
BDE-47 BDE-85 BDE-99 BDE-100 BDE-153 BDE-154 BDE-183
Ave
rage
reco
veri
es (%
)
Room temperature ̴25° C (n=2) 40° C (n=4) 60° C (n=6) with air flow
without air flow
147
Figure A2.4. Distribution of PBDEs amongst spiked filter paper, rinse of chamber walls, cotton and polyester fabric squares in experiments without air flow at 40oC and 60oC.
Figure A2.5. Distribution of PBDEs amongst spiked filter paper, rinse of chamber walls, PUF that collected outflowing air, cotton and polyester fabric squares in experiments with air flow at room temperature, 40oC and 60oC.
0
20
40
60
80
100 A
vera
ge %
dis
rtib
utio
n of
PB
DE
s in
cham
ber
com
pone
nts Filter Paper Chamber Rinse Cotton Polyester
40°C; 24 hours 60°C; 24 hours
without air flow
0
20
40
60
80
100
120
Ave
rage
% d
isrt
ibut
ion
of P
BD
Es i
n ch
ambe
r co
mpo
nent
s
Filter paper Chamber Rinse PUF Cotton Polyester
Room temp; 1 week 40ºC; 72 hours
with air flow
60º C; 72 hours
148
Figure A2.6. Planar area normalized distribution of PBDEs amongst fabrics and chamber wall in experiments with air flow at room temperature, 40oC and 60oC.
Figure A2.7. PBDE mass per unit area (ng/cm2, at 25°C) sorbed to cotton and polyester and air concentrations (ng/m3) as a function of (a) octanol-air partition coefficient (log KOA) and (b) vapour pressure (Pa) in chambers with air flow conditions. Values of log KOA and log vapour pressure (at 25°C) were estimated using EPISuite 4.1 software models KOAWIN v1.10 and MPBPVP v1.43, respectively (USEPA, 2012).
0%
20%
40%
60%
80%
100% D
istr
ibut
ion/
cm2 of
com
pone
nt
Polyester Cotton Chamber Rinse
0.001
0.01
0.1
1
10 11 12 13 14 15
ng/c
m2
Log KOA
Cotton Polyester Air conc.
0.001
0.01
0.1
1
1.E-08 1.E-06 1.E-04
ng/c
m2
Vapour pressure
Cotton Polyester Air conc. (b) (a)
149
Figure A2.8. Log K’D (planar area normalized) as a function of Log KOA and VP.
y = 0.021x + 4.0 r² = 0.06, p>0.05
4.1
4.2
4.3
4.4
4.5
10 12 14 16
Log
K'c
otto
n-ai
r y = -0.024x + 4.13 r² = 0.07, p>0.05
4.1
4.2
4.3
4.4
4.5
-8 -6 -4 -2
y = 0.106x + 3.13 r² = 0.44, p>0.05
4.0
4.5
5.0
10 12 14 16
Log
K'p
olye
ster
-air
y = -0.114x + 3.80 r² = 0.41, p>0.05
4.0
4.5
5.0
-8 -6 -4 -2
y = 0.216x + 1.42 r² = 0.62, p<0.05
3.0
3.5
4.0
4.5
5.0
10 12 14 16
Log
K'st
eel-a
ir
Log KOA
y = -0.2161x + 2.8922 r² = 0.4975, p>0.05
3.0
3.5
4.0
4.5
5.0
-8 -6 -4 -2 Log VP
150
Table A2.1. PBDEs sorbed to cotton and polyester in without air flow experiments at 40oC and 60oC after 24 hours
40°C; 24 hours
60°C; 24 hours
BDE-47 BDE-100
BDE-99 BDE-85 BDE-153
BDE-154
BDE-183
BDE-47
BDE-100
BDE-99
BDE-85
BDE-153
BDE-154
BDE-183
ng/cm2 fabric Cotton 0.50 0.19 0.12 0.06 0.04 0.06 0.02
0.47 0.12 0.19 0.26 0.06 0.11 0.02
Polyester 0.47 0.20 0.17 0.13 0.11 0.13 0.02
0.63 0.10 0.18 0.27 0.04 0.07 0.02 ng/g fabric Cotton 35 4.4 8.4 13 4.4 2.5 1.2 35 9.3 14 19 7.9 4.4 1.6 Polyester 1340 380 475 567 375 303 44 1720 275 502 733 205 102 58 ng/cm2 BET-SSA Cotton 0.0035 0.0004 0.0008 0.0013 0.0004 0.0003 0.0001 0.0035 0.0009 0.0014 0.0019 0.0008 0.0004 0.0002 Polyester 0.13 0.04 0.05 0.06 0.04 0.03 0.004 0.17 0.03 0.05 0.07 0.02 0.01 0.006
Table A2.2 PBDEs sorbed to cotton and polyester in experiments with air flow at 25oC, 40oC and 60oC after 72 hours
Room temperature (~25°C); 72 hours 40°C; 72 hour 60°C; 72 hours
BDE-47
BDE-100
BDE-99
BDE-85
BDE-153
BDE-154
BDE-183
BDE-47
BDE-100
BDE-99
BDE-85
BDE-153
BDE-154
BDE-183
BDE-47
BDE-100
BDE-99
BDE-85
BDE-153
BDE-154
BDE-183
ng/cm2 fabric
Cotton 0.28 0.05 0.10 0.17 0.03 0.01 0.01
0.26 0.04 0.07 0.11 0.04 0.03 0.04 0.19 0.09 0.13 0.16 0.10 0.06 0.03 Polyester 0.34 0.08 0.12 0.19 0.05 0.02 0.02
0.11 0.04 0.05 0.05 0.03 0.03 0.04 0.12 0.11 0.10 0.08 0.06 0.09 0.06
ng/g fabric Cotton 16 2.8 6.0 9.8 1.9 0.9 0.4
16 2.6 4.2 6.6 2.4 2.0 2.5 9.7 4.4 6.8 8.4 4.9 3.2 1.4
Polyester 70 17 25 40 9.7 4.7 3.6
22 8.2 10 10 6.6 6.5 7.7 27 24 21 17 13 19 13 ng/cm2 BET-SSA Cotton 0.0023 0.0004 0.0008 0.0014 0.0003 0.0001 0.0000
0.0022 0.0004 0.0006 0.0009 0.0003 0.0003 0.0003 0.0013 0.0006 0.0009 0.0012 0.0007 0.0004 0.0002
Polyester 0.098 0.023 0.035 0.056 0.014 0.007 0.005
0.031 0.012 0.014 0.015 0.009 0.009 0.011 0.038 0.033 0.029 0.024 0.018 0.026 0.018
151
Table A2.3. BET-SSA-normalized distribution coefficients (pg/m2-BET fabric to pg/m3 air concentration; K’cotton-air, and K’polyester-air, m) at room temperature (one week), and 40°C and 60°C (72 hours).
BDE-47 BDE-85 BDE-99 BDE-100 BDE-153 BDE-154 BDE-183
K’cotton-air (m) Room temp. (~25°C) 64 370 160 139 689 231 701 40°C 54 69 66 68 110 24 40 60°C 20 8 8 10 11 5 61
K’polyester-air (m) Room temp. (~25°C) 1799 20311 4994 2842 18410 13687 66057 40°C 2319 4075 2808 2810 5625 1305 4145 60°C 283 265 203 163 313 169 1884
References
Mather, R. R., Wardman, R. H. 2011. The Chemistry of Textile Fibres. Royal Society of chemistry.
Rauert, C., Harrad, S., Stranger, M., Lazarov, B. 2015. Test chamber investigation of the volatilization from source materials of brominated flame retardants and their subsequent deposition to indoor dust. Indoor Air, 25, 393–404. doi:doi:10.1111/ina.12151
USEPA 2012. http://www.epa.gov/tsca-screening-tools/epi-suitetm-estimation-program-interface
152
Appendix 3: Supporting information for chapter 4 Chemicals of Interest:
Table A3.1. Details of chemicals investigated in this study. Practical abbreviations (PRABs) are
given in parenthesis as reported by Bergman et al., (2012).
Abbreviation (PRABs) Compound name CAS no. Molecular weight
New flame-retardants (NFRs) ATE (TBP-AE) Tribromophenyl allyl ether 3278-89-5 370 PBBz Pentabromobenzene 608-90-2 472 PBT Pentabromotoluene 87-83-2 486 HBB Hexabromobenzene 87-82-1 551 EH-TBB (TBB) Ethylhexyl-tetrabromobenzene 183658-27-7 550 BEH-TEBP (TBPH) Bis(2-ethlyhexyl)tetrabromophthalate 26040-51-7 706 s-DP (s-DDC-CO) Dechlorane plus
13560-89-9 653
a-DP(a-DDC-CO) Dechlorane plus 653 OBIND (OBTMPI) Brominated trimethylphenyl indane 155613-93-7 867 DBDPE Decabromodiphenylethane 84852-53-9 971
Polybrominated diphenyl ether (PBDEs) BDE-17 2,2',4-Tribromodiphenyl ether 147217-75-2 437 BDE-28 2,4,4'-Tribromodiphenyl ether 41318-75-6 407 BDE-71 2,3',4',6-Tetrabromodiphenyl ether 189084-62-6 486 BDE-47 2,2',4,4'-Tetrabromodiphenyl ether 5436-43-1 486 BDE-66 2,3',4,4'-Tetrabromodiphenyl ether 189084-61-5 486 BDE-100 2,2',4,4',6-Pentabromodiphenyl ether 189084-64-8 565 BDE-99 2,2',4,4',5-Pentabromodiphenyl ether 60348-60-9 565 BDE-85 2,2',3,4,4'-Pentabromodiphenyl ether 182346-21-0 565 BDE-154 2,2',4,4',5,6'-Hexabromodiphenyl ether 207122-15-4 644 BDE-153 2,2',4,4',5,5'-Hexabromodiphenyl ether 68631-49-2 644 BDE-138 2,2',3,4,4',5'-Hexabromodiphenyl ether 182677-30-1 644 BDE-183 2,2',3,4,4',5',6-Heptabromodiphenyl ether 207122-16-5 722 BDE-190 2,2',3',4,4',5',6-Heptabromodiphenyl ether 83992-70-5 722 BDE-209 Decabromodiphenyl ether 1163-19-5 959
Phthalates DEP Diethyl Phthalate 84-66-2 222 DiBP Di isobutyl phthalate 84-69-5 278 DnBP Di-n-butyl phthalate 84-74-2 278
153
BzBP Benzyl butyl phthalate 85-68-7 312 DEHP Di (2-ethylhexyl) phthalate 117-81-7 391 DiNP Di isononyl phthalate 68515-48-0 419
QA/QC: Instrument detection limit was calculated from lowest calibration standard as amount of
chemical that gives a signal to noise ratio of 3:1. Limit of detection (LOD) was calculated as the
average of the laboratory blanks (n=7) run with each batch of samples. The non-detects
(chromatographic peaks not quantifiable) or the sample values <LOD were substituted with the
value of LOD divided by square root of two for statistical calculations.
Table A3.2. Instrument detection limit (IDL) and limit of detection (LOD) of chemicals
Chemical IDL (pg) or (*ng)
LOD (pg or *ng/dm2 fabric)
ATE 3.8 1.2 PBBz 1.6 2.7 PBT 2.8 3.6 HBB 1.7 17 EH-TBB 29 1.3 BEH-TEBP 30 1.7 s-DP 18 2.2 a-DP 18 2.4 OBIND 20 1.7 DBDPE 68 8 BDE-17 8 1.3 BDE-28 1 3.8 BDE-71 6.4 3.5 BDE-47 8.9 16 BDE-66 9.2 10 BDE-100 6.4 16 BDE-99 10 13 BDE-85 13 4.1 BDE-154 6.4 1.4 BDE-153 10 6.9 BDE-138 17 3.5
154
BDE-183 13 4.2 BDE-190 48 4.9 BDE-209 23 28 DEP* 0.04 10 DiBP* 0.04 1.5 DnBP* 0.03 5.4 BzBP* 0.06 0.6 DEHP* 0.07 1.8 DiNP* 0.70 11
Results:
Figure A3.1. SEM images of cotton and rayon’s fabric weave (top) under 30× magnification and single strand structure (bottom) under 2000× magnification.
155
Table A3.3. Descriptive statistics for halogenated flame retardants and phthalates measured in cotton samples after 28 day deployment in Greater Toronto Area homes and offices in summer 2013.
Chemical Bedroom (n=17) Living room (n=14) Office (n=5) Average GM Range Average GM Range Average GM Range NFRs (pg/dm2 of fabric) ATE 38 7.0 <LOD -333 11 4.1 <LOD -55 10 7.5 <LOD -22 PBBz 59 38 7.3-247 52 38 13 -248 63 45 <LOD -180 PBT 156 92 16.3-742 145 98 19-429 145 126 39-203 HBB 134 87 <LOD -851 119 67 <LOD --467 637 233 60-2530 EH-TBB 265 67 4.1-1930 370 76 4.9-3840 208 93 8.2-398 BEH-TEBP 6.5 2.5 <LOD -74 4.8 2.4 <LOD -40 11 4.8 <LOD -36 s-DP 6.7 4.0 <LOD -51 5.5 4.0 <LOD -16 36 5.5 <LOD -167 a-DP 16 7.6 <LOD -65 7.5 5.7 <LOD -19 64 7.4 <LOD -304 OBIND 2.0 1.7 <LOD -4.1 2.7 2.1 <LOD -9.0 126 71 <LOD -157 DBDPE nd nd nd 96 11 <LOD -1230 nd nd nd PBDEs (pg/dm2 of fabric) BDE-17 67 47 12-311 102 42 5.7-855 254 16 49-674 BDE-28 308 131 22-1586 277 107 16-2290 689 252 8.7-1927 BDE-71 113 59 14-633 162 45 <LOD --1104 512 387 118-1162 BDE-47 2430 1560 477-12290 2980 1204 276-22480 19150 13810 3625-44738 BDE-66 28 19 <LOD -116 37 25 <LOD -193 193 128 38-415 BDE-100 138 113 <LOD -373 183 118 <LOD -885 934 658 140-2264 BDE-99 397 310 114-1290 440 255 <LOD -2022 2774 1850 480-7037 BDE-85 9.0 5.4 <LOD -37 12 5.9 <LOD -64 68 47 17-168 BDE-154 10 5.0 <LOD -51 15 6.7 <LOD -74 84 73 38-168 BDE-153 18 13 <LOD -57 23 15 <LOD -84 59 56 34-90 BDE-138 6.0 5.0 <LOD -19 5.7 4.5 <LOD -16 11 7.5 <LOD -25 BDE-183 9.0 5.5 <LOD -70 19 11 <LOD -74 58 44 nd BDE-190 4.0 3.2 <LOD -9.2 12 4.4 <LOD -96 22 11 <LOD -52 BDE-209 250 125 <LOD -780 4140 199 <LOD -54854 nc nc nc
156
Phthalates (ng/dm2 of fabric) DEP 79 27 <LOD -503 118 52 <LOD -341 99 94 66-159 DiBP 274 29 <LOD -1730 333 42 <LOD -2400 816 215 4.1-3056 DnBP 238 44 <LOD -1008 341 59 <LOD -1870 1493 444 <LOD -4756 BzBP 9.3 2.3 <LOD -68 13 2.4 <LOD -131 75 20 <LOD -319 DEHP 175 23 <LOD -1203 156 22 <LOD -1232 482 166 2.4-1025 DiNP 65 20 <LOD -316 52 26 <LOD -165 207 133 <LOD -438
(LOD=limit of detection; nd=non-detectable in all samples; nc= non-calculable as data discarded due to contamination issue)
Table A3.4. Descriptive statistics for halogenated flame retardants and phthalates measured in rayon samples after 28 day deployment in Greater Toronto Area homes and offices in summer 2013.
Chemical Bedroom (n=17) Living room (n=14) Office (n=5)
Average GM Range Average GM Range Average GM Range NFRs (pg/dm2 of fabric) ATE 120 36 <LOD -535 31 12 <LOD -200 21 7.5 <LOD -89 PBBz 410 272 80- 2199 472 259 87-3645 375 191 <LOD -1294 PBT 351 228 27- 1267 357 240 35- 1278 354 223 20- 581 HBB 209 126 <LOD -1229 176 100 <LOD -711 917 390 120- 3615 EH-TBB 59 17 <LOD -280 307 32 <LOD -1411 114 13 <LOD -478 BEH-TEBP 1.9 1.5 <LOD -9.0 11 3.1 <LOD -93 17 2.9 <LOD -78 s-DP 9.2 3.6 <LOD -73 4.0 2.4 <LOD -20 22 4.6 <LOD -100 a-DP 17 6.8 <LOD -93 6.2 3.7 <LOD -15 36 5.8 <LOD -169 OBIND 23 6.7 <LOD -254 10 4.3 <LOD -52 1213 306 <LOD -2975 DBDPE 26 14 <LOD -160 430 18 <LOD -5810 257 110 <LOD -873 PBDEs (pg/dm2 of fabric) BDE-17 120 69 18- 837 131 47 <LOD -932 465 372 88- 824 BDE-28 303 122 14- 2487 330 86 <LOD -2752 1277 980 220- 2244
157
BDE-71 100 53 <LOD -514 67 27 <LOD -298 638 502 99- 942 BDE-47 2958 1685 452- 15758 2810 1059 154- 19550 23843 17710 2643- 37250 BDE-66 35 24 <LOD -166 30 15 <LOD -185 181 124 18- 364 BDE-100 156 118 34- 565 148 104 27- 465 1248 926 219- 2766 BDE-99 414 303 116- 1363 384 240 32- 1290 2778 2115 345- 4103 BDE-85 10 8.3 <LOD -46 10 5.9 <LOD -69 45 25 <LOD -72 BDE-154 7.6 5.2 <LOD -32 10 5.1 <LOD -49 90 76 32- 177 BDE-153 20 16 <LOD -58 26 22 <LOD -74 70 61 20- 103 BDE-138 Nd Nd Nd 7.1 6.1 <LOD -11 18 12 <LOD -- 35 BDE-183 7.6 5.4 <LOD -29 11 7.6 <LOD -36 93 46 <LOD -251 BDE-190 Nd Nd Nd Nd Nd Nd 155 55 <LOD -546 BDE-209 2260 96 <LOD -15188 8350 74 <LOD -99000 nc nc nc Phthalates (ng/dm2 of fabric) DEP 104 56 <LOD-329 80 46 <LOD-280 140 127 48-193 DiBP 14 3.9 <LOD-105 67 5.7 <LOD-741 96 7.6 <LOD -471 DnBP 32 4.8 <LOD-295 80 5.9 <LOD-934 220 16 <LOD -1080 BzBP 2.7 1.3 <LOD-13 18 1.6 <LOD-210 1.8 1.3 <LOD-4.9 DEHP 23 3.0 <LOD-156 96 5.0 <LOD-775 109 8.7 <LOD-503 DiNP 29 24 1.6-43 71 35 3.3-426 33 23 <LOD-100
(LOD=limit of detection; nd=non-detectable in all samples; nc= non-calculable as data discarded due to contamination issue)
158
0.1
1
10
100
1000
10000
100000 pg
/dm
2 C_H1BR C_H2BR C_H3BR C_H6BR C_H7BR C_H8BR C_H9BR C_H11BR C_H12BR C_H14BR C_H16BR C_H17BR C_H18BR1 C_H18BR2 C_H19BR C_H20BR C_H22BR
0.1
1
10
100
1000
10000
100000
pg/d
m2
C_H1LR C_H2LR C_H3LR C_H4LR C_H5LR C_H6LR C_H7LR C_H11LR C_H14LR C_H15LR C_H16LR C_H17LR C_H20LR C_H21LR
0.1
1
10
100
1000
10000
100000
pg/d
m2
R_H1BR R_H2BR R_H3BR R_H6BR R_H7BR R_H8BR R_H9BR R_H11BR R_H12BR R_H14BR R_H16BR R_H17BR R_H18BR1 R_H18BR2 R_H19BR R_H20BR R_H22BR
159
Figure A3.2. Concentration (pg/dm2 fabric) of flame retardants in cotton and rayon fabrics at each home location. Legend: C= cotton, R= rayon, H= home, BR= bedroom, LR= Living room.
0.1
1
10
100
1000
10000
100000
pg/d
m2
R_H1LR R_H2LR R_H3LR R_H4LR R_H5LR R_H6LR R_H7LR R_H11LR R_H14LR R_H15LR R_H16LR R_H17LR R_H20LR R_H21LR
160
Figure A3.3. Concentration (ng/dm2 fabric) of phthalates in cotton and rayon fabrics at each home location. Legend: C= cotton, R= rayon, H= home, BR= bedroom, LR= Living room.
0.1
1
10
100
1000
10000
ng/d
m2
C_H1BR C_H2BR C_H3BR C_H6BR C_H7BR C_H8BR C_H9BR C_H11BR C_H12BR C_H14BR C_H16BR C_H17BR C_H18BR1 C_H18BR2 C_H19BR C_H20BR C_H22BR
0.1
10
1000
ng/d
m2
C_H1LR C_H2LR C_H3LR C_H4LR C_H5LR C_H6LR C_H7LR C_H11LR C_H14LR C_H15LR C_H16LR C_H17LR C_H20LR C_H21LR
0.1
10
1000
ng/d
m2
R_H1BR R_H2BR R_H3BR R_H6BR R_H7BR R_H8BR R_H9BR R_H11BR R_H12BR R_H14BR R_H16BR R_H17BR R_H18BR1 R_H18BR2 R_H19BR R_H20BR R_H22BR
0.1
1
10
100
1000
DEP DIBP DNBP BzBP DEHP DiNP
ng/d
m2
R_H1LR R_H2LR R_H3LR R_H4LR R_H5LR R_H6LR R_H7LR R_H11LR R_H14LR R_H15LR R_H16LR R_H17LR R_H20LR R_H21LR
161
Figure A3.4. Uptake profiles of phthalates as shown by cotton (blue diamonds) and rayon (red squares) over 56 days of deployment expressed according to planar surface area.
Table A3.5. Mass sequestered by cotton and rayon fabrics on day 56th used for estimating distribution coefficients, K’cotton-air or K’rayon-air.
Chemical Ccotton (pg/dm2) C’cotton (pg/m3 fabric) Crayon (pg/dm2) C’rayon (pg/m3 fabric)
PBBz 85 1.7 x107 241 4.8x 107 PBT 204 4.1 x107 238 4.8 x 107 BDE-17 450 9.0 x107 510 1.0 x 108 BDE-28 1530 3.1 x108 1993 4.0 x 108 BDE-47 29900 6.0 x109 24098 4.8 x 109 BDE-66 465 9.3 x107 428 8.6 x 107 BDE-100 1704 3.4 x108 1155 2.3 x 108 BDE-99 4475 8.9 x108 3383 6.8 x 108
162
Table A3.6. Mass sequestered by cotton and rayon fabrics on day 56 of sampling (reported in Table A3.5) normalized to BET-SSA of cotton and rayon fabrics (pg/dm2-BET).
Chemical Ccotton (pg/dm2-BET) Crayon (pg/dm2-BET) PBBz 0.72 7.5 PBT 1.7 7.4 BDE-17 3.8 16 BDE-28 13 62 BDE-47 254 745 BDE-66 3.9 13 BDE-100 14 36 BDE-99 38 105
Table A3.7. Mass transfer coefficients calculated for halogenated flame retardants based on 56 day uptake (MTC, m/h), calculated according to planar surface area of fabric.
Chemical MTC-cotton MTC-rayon
PBBz 1.5 3.8
PBT 2.6 3.1
BDE-17 1.5 1.8
BDE-28 1.9 2.3
BDE-47 2.6 2.6
BDE-66 2.0 2.1
BDE-100 2.2 2.6
BDE-99 2.7 2.8
163
Figure A3.5. Mass transfer coefficients (MTC m/h) as a function of (a) Log KOA and (b) vapour pressure (Pa).
Table A3.8. Measured distribution coefficients (K’cotton-air or K’rayon-air), modeled partition coefficients (Kpp-LFER and KCOSMO-RS ) predicted using pp-LFER model reported by Holmgren et al. (2012) and COSMO-RS model of Eckert and Klamt (2002) and estimated time to 95% of equilibration (t95) (Equation 5 in Shoeib and Harner (2002).
Chemical Log K’cotton-air (C’cotton/Cair;
unitless)
Log K’rayon-air (C’rayon/ Cair;
unitless)
K’area-cotton (m)
K’area -rayon (m)
Log Kpp-
LFER
Log KCOSMO-
RS
t95 (years)
PBBz 6.5 6.9 1548 4400 - 6.1 -
PBT 6.9 6.9 3792 4427 9.9 6.1 -
BDE-17 6.6 6.6 1881 2135 - 8.4 14
BDE-28 6.6 6.8 2197 2862 10.3 8.4 12
BDE-47 6.8 6.8 3516 2834 11.3 9.4 82
BDE-66 7.1 7.0 5768 5322 - 9.4 98
BDE-100 7.0 6.9 4917 3717 12.2 10 388
BDE-99 6.8 6.7 3294 2233 12.5 10 347
Note: t95 was calculated using KCOSMO-RS (not reported for PBBz and PBT).
1.5
2.0
2.5
3.0
3.5
4.0
8 10 12 14
MT
C (m
/h)
Log KOA
Cotton Rayon
1.5
2.0
2.5
3.0
3.5
4.0
1.E-06 1.E-05 1.E-04 1.E-03 1.E-02 Vapour pressure (Pa)
(a) (b)
164
References
Bergman, A., Andreas, R., Law, R.J., Boer, J. de, Covaci, A., Alaee, M., Birnbaum, L., Patreas, M., Rose, M., Sakai, S., Van den Eede, N., Van der Veen, I. 2012. A novel abbreviation standard for organobromine, organochlorine and organophosphorus flame retardants and some characteristics of the chemicals. Environment International, 42(2), 57–82. doi:10.1016/j.envint.2012.08.003
Eckert, F., Klamt, A. 2002. Fast Solvent Screening via Quantum Chemistry: COSMO-RS Approach. AIChE Journal, 48(2), 369–385. doi:10.1002/aic.690480220
Holmgren, T., Persson, L., Andersson, P. L., Haglund, P. 2012. A generic emission model to predict release of organic substances from materials in consumer goods. The Science of the Total Environment, 437, 306–314. doi:10.1016/j.scitotenv.2012.08.020
Shoeib, M., Harner, T. 2002. Characterization and comparison of three passive air samplers for persistent organic pollutants. Environmental Science and Technology, 36(19), 4142–4151. doi:10.1021/es020635t
165
Appendix 4: Supporting information for chapter 5
From clothing to laundry water: Investigating the fate of semi-volatile organic
compounds sorbed to fabrics.
Methods
Table A4.1. Details of chemicals analyzed. Values of water solubility and log KOW were estimated using USEPA EPI Suite’s WSKOWWIN v. 1.42 and KOWWIN v.1.68 models.
Full name CAS number Molecular weight (g/mol)
Water solubility
mg/L at 25°
Log Kow
Organophosphate esters (OPEs) TnBP Tributyl phosphate 126-73-8 266 7.4 3.8 TCEP Tris(2-chloroethyl) phosphate 115-96-8 285 878 1.6 TCPP-1 (TCiPP)
Tris(2-chloroisopropyl) phosphate 13674-84-5 328 52 2.9
TCPP-2 76025-05-6 328 52 2.9 TCPP-3 76649-15-5 328 52 2.9 TPhP Triphenyl phosphate 115-86-6 326 1.0 4.7 TDCiPP Tris(1,3-dichloro-2-propyl)
phosphate 13674-87-8 431 1.5 3.7
EHDPP 2-Ethylhexyl diphenyl phosphate 1241-94-7 362 0.07 6.3 New flame-retardants (NFRs)
ATE (TBP-AE) Tribromophenyl allyl ether 3278-89-5 370 7.8x10-2 5.6 PBBz Pentabromobenzene 608-90-2 472 3.4x10-3 6.4 PBT Pentabromotoluene 87-83-2 486 9.3x10-4 7.0 PBEB 85-22-3 501 2.9x10-4 7.5 HBB Hexabromobenzene 87-82-1 551 2.2x10-3 7.3 TBB (EH-TBB) Ethylhexyl-tetrabromobenzene 183658-27-27 550 1.1x10-5 8.8 TBPH (BEH-TEBP)
Bis(2-ethlyhexyl)tetrabromophthalate 26040-51-7 706 1.9x10-9 12.0
s-DP (s-DDC-CO)
Syn-Dechlorane plus
13560-89-9 653 1.7x10-8 11.27 a-DP(a-DDC-CO)
Anti-Dechlorane plus
OBIND (OBTMPI)
Brominated trimethylphenyl indane 155613-93-7 867 1.9x10-11 13.0
DBDPE Decabromodiphenylethane 84852-53-9 971 1.2x10-12 13.64 Polybrominated diphenyl ether (PBDEs)
BDE-17 2,2',4-Tribromodiphenyl ether 147217-75-2 407 2.6x10-2 5.88 BDE-28 2,4,4'-Tribromodiphenyl ether 41318-75-6 407 2.6x10-2 5.88
166
BDE-71 2,3',4',6-Tetrabromodiphenyl ether
189084-62-6 486 1.5 x10-3 6.77
BDE-47 2,2',4,4'-Tetrabromodiphenyl ether
5436-43-1 486 1.5 x10-3 6.77
BDE-66 2,3',4,4'-Tetrabromodiphenyl ether
189084-61-5 486 1.5 x10-3 6.77
BDE-100 2,2',4,4',6-Pentabromodiphenyl ether
189084-64-8 565 7.9 x10-5 7.66
BDE-99 2,2',4,4',5-Pentabromodiphenyl ether
60348-60-9 565 3.9 x10-4 7.66
BDE-85 2,2',3,4,4'-Pentabromodiphenyl ether
182346-21-0 565 7.9 x10-5 7.66
BDE-154 2,2',4,4',5,6'-Hexabromodiphenyl ether
207122-15-4 644 4.2 x10-6 8.55
BDE-153 2,2',4,4',5,5'-Hexabromodiphenyl ether
68631-49-2 644 4.2 x10-6 8.55
BDE-138 2,2',3,4,4',5'-Hexabromodiphenyl ether
182677-30-1 644 4.1 x10-6 8.55
BDE-183 2,2',3,4,4',5',6-Heptabromodiphenyl ether
207122-16-5 722 2.1 x10-7 9.44
BDE-190 2,2',3',4,4',5',6-Heptabromodiphenyl ether
83992-70-5 722 2.1 x10-7 9.44
BDE-209 Decabromodiphenyl ether 1163-19-5 959 2.8 x10-11 12.11 Phthalates
DiBP Di isobutyl phthalate 84-69-5 278 5.1 4.46 DnBP Di-n-butyl phthalate 84-74-2 278 2.3 4.61 BzBP Benzyl butyl phthalate 85-68-7 312 0.9 4.84 DEHP Di (2-ethylhexyl) phthalate 117-81-7 391 1.1x10-3 8.39 DiNP Di isononyl phthalate 68515-48-0 419 2.3x10-5 9.37
Table A4.2. Instrument detection limits (IDL) and limits of quantification (LOQ) of chemicals analyzed.
IDL (pg or *ng)
LOQ (pg or *ng)
TnBP 20 67 TCEP 234 779 TCPP-1 94 314 TCPP-2 112 375 TCPP-3 115 385 TPhP 76 253 TDCiPP 14 48 EHDPP 83 276 ATE 1.1 3.8
167
PBBz 2.1 6.9 PBT 2.5 8.5 PBEB 3.0 9.9 HBB 3.7 12 TBB (EH-TBB) 13 44 TBPH (BEH-TEBP) 33 111 s-DP (s-DDC-CO) 2.3 7.7 a-DP(a-DDC-CO) 3.4 11 OBIND (OBTMPI) 11 38 DBDPE 209 696 BDE-17 2.8 9.3 BDE-28 2.1 6.9 BDE-71 5.1 17 BDE-47 5.5 18 BDE-66 5.8 19 BDE-100 13 44 BDE-99 5.6 19 BDE-85 11 36 BDE-154 6.8 22 BDE-153 7.6 25 BDE-138 12 42 BDE-183 5.8 19 BDE-190 16 55 BDE-209 36 119 DiBP* 0.15 0.50 DnBP* 0.15 0.49 BzBP* 0.27 0.89 DEHP* 0.24 0.79 DiNP* 1.9 6.5
IDL= calculated as amount of chemical that gives a signal to noise ratio of 3:1
LOQ= calculated as amount of chemical that gives a signal to noise ratio of 10:1
Details of extraction and analysis
ASE operating conditions:- temperature: 70°C, pressure: 1500 psi, heat time: 5 min, static time:
4 min, flush volume: 60%, purge time: 60 s, and static cycles: 3.
GC-MS operating conditions: OPE (except TDCiPP) and phthalate analysis was performed using
a 30 m DB-5 MS column (Agilent technologies, 0.25 mm i.d. and 0.25 µm film thickness) with
an EI source. For OPEs, the oven temperature program was: initial at 75°C hold for 1 min, 15°C
168
min-1 to 180°C and hold for 1 min, 6°C min-1 to 270°C, 20°C min-1 to 310°C and hold for 4 min.
For phthalates, the oven temperature program was: initial at 75°C hold for 3 mins, 10°C min-1 to
320°C and hold for 3 min. HFRs (PBDEs and NFRs) and TDCiPP analysis was performed using
15 m DB-5 MS column (Agilent technologies, 0.25 mm i.d. and 0.25 µm film thickness) with a
NCI source with the following oven temperature program: initial at 100°C hold for 1.5 min,
12°C min-1 to 250°C, then 60°C min-1 to 290°C, hold for 3 min and finally 40°C min-1 to 320°C,
hold for 11 min.
Laundry soap ingredients (as obtained from http://www.seventhgeneration.com/natural-laundry-
detergent?v=31): water, laureth-6 (plant-derived cleaning agent), sodium lauryl sulfate (plant-
derived cleaning agent), sodium citrate (plant-derived water softener), glycerin (plant-derived
enzyme stabilizer), sodium chloride (mineral-based viscosity modifier), oleic acid (plant-derived
anti-foaming agent), sodium hydroxide (mineral-based pH adjuster), calcium chloride (mineral-
based enzyme stabilizer), citric acid (plant-derived pH adjuster), protease, amylase, and
mannanase (plant-derived enzyme blend soil removers), and benzisothiazolinone and
methylisothiazolinone (synthetic preservatives).
Results
For mass balance: Group 1= Total mass accumulated on cotton and polyester fabrics that were
directly extracted on ASE after deployment.
Group 2= Mass released in laundry water + mass left on fabrics after laundering and drying in
desiccator
Group 3= Mass released in laundry water + mass left on fabrics after laundering and drying in
electric dryer
169
Table A4.3. Average concentrations of chemicals (ng/dm2 fabric planar surface area) accumulated by cotton and polyester fabrics after 30 day deployment (group 1).
Chemicals Cotton Polyester Average ± Standard deviation (Detection frequency)
DiBP 650±157 (100%) 70±14 (70%) DnBP 914±312 (100%) 179±38 (90%) BzBP 370±53 (100%) 421±125 (100%) DEHP 1363±492 (90%) 1091±460 (90%) DiNP 178±95 (90%) 187±62 (70%)
PBBz 0.1±0.05 (100%) 0.2±0.05 (100%) PBT 0.4±0.1 (90%) 0.4±0.1 (90%) HBB 1±0.2 (90%) 0.9±0.3 (90%) EH-TBB 1±0.5 (100%) 1.3±0.8 (100%) BDE-17 1±0.3 (100%) 0.84±0.1 (100%) BDE-28 2.2±0.6 (100%) 2.3±0.8 (100%) BDE-47 46±11 (100%) 53±18 (100%) BDE-66 0.7±0.2 (100%) 0.8±0.3 (100%) BDE-100 2.6±0.7 (100%) 3.5±1.2 (100%) BDE-99 10±2.9 (100%) 15±4.5 (100%)
TnBP 22±9 (90%) 3.2±1.3 (50%) TCEP 57±49 (70%) 62±41 (70%) TCPP-1 588±422 (80%) 109±88 (100%) TCPP-2 347±191 (80%) 80±55 (100%) TCPP-3 115±91 (80%) 19±7.8 (100%) TPhP 32±13 (90%) 21±7.5 (100%) TDCiPP 36±25 (100%) 13±7.6 (90%) EHDPP 9.3±5.5 (100%) 3.8±1.7 (100%)
170
Table A4.4. Average concentrations of chemicals ± standard deviation transferred to laundry water (ng/L.dm2 fabric) and remaining sorbed to cotton and polyester fabrics (ng/dm2 fabric). Note: group 2 fabrics were dried in desiccator whereas, group 3 fabrics were dried in an electric dryer. All concentrations normalized to planar surface area.
Group 2 Group 3 Cotton Polyester Cotton Polyester
In laundry water
Sorbed to fabric
In laundry water
Sorbed to fabric
In laundry water
Sorbed to fabric
In laundry
water Sorbed to
fabric DiBP 454±79 <LOQ 59±20 <LOQ 322±51 154±54 37±15 <LOQ DnBP 565±137 113±57 118±57 46±15 418±139 149±36 68±28 108±47 BzBP 196±52 60±26 155±31 144±30 194±83 69±16 169±97 37±34 DEHP 362±296 757±345 339±322 641±205 348±114 709±139 168±91 591±317 DiNP <LOQ 141±62 <LOQ 200±67 <LOQ 239±54 <LOQ 272±268 PBBz <LOQ 0.06±0.02 <LOQ 0.10±0.04 <LOQ 0.08±0.02 <LOQ 0.26±0.09 PBT <LOQ 0.24±0.1 <LOQ 0.23±0.08 <LOQ 3.1±2.5 <LOQ 4.5±2.5 HBB <LOQ 0.56±0.17 <LOQ 0.59±0.15 <LOQ 0.62±0.12 <LOQ 1.2±0.38 EH-TBB <LOQ 0.84±0.3 <LOQ 1.1±0.05 <LOQ 0.71±0.19 <LOQ 0.9±0.45 BDE-17 0.05±0.02 0.50±0.2 0.01±0.0 0.69±0.3 0.04±0.01 0.60±0.17 <LOQ 0.99±0.16 BDE-28 0.06±0.02 1.3±0.6 0.02±0.01 2.3±0.78 0.08±0.05 1.5±0.32 <LOQ 3.1±0.69 BDE-47 0.67±0.2 33±15 0.81±0.8 61±15 0.66±0.34 33±7.4 0.24±0.13 84±18 BDE-66 <LOQ 0.57±0.3 0.02±0.01 0.86±0.23 <LOQ 0.33±0.10 <LOQ 1.3±0.69 BDE-100 0.04±0.04 1.8±0.85 0.29±0.27 3.7±1.1 0.06±0.03 1.5±0.29 0.11±0.04 5.0±1.0 BDE-99 0.22±0.12 7.4±3.8 1.1±0.8 18±6.4 <LOQ 6.0±1.2 0.44±0.4 21±6.8 TnBP 16±5 <LOQ 1.5±1.5 <LOQ 17±5.0 0.95±0.39 1.1±0.34 <LOQ TCEP 439±197 <LOQ 118±65 28±13 338±137 2.6±2 110±59 <LOQ TCPP-1 1684±771 1.9±1.5 168±73 6.2±2.5 1517±729 3.1±1.5 155±68 0.6±0.9 TCPP-2 694±301 3.0±4.3 106±39 4.5±2.8 636±286 2.5±1.2 93±38 0.8±1.2 TCPP-3 104±42 2.2±1.6 26±7.3 1.1±0.8 100±42 5.9±2.3 24±14 0.3±0.08 TDiCPP 18±11 <LOQ 9.6±7.0 <LOQ 11±4.7 5.0±2.7 6.6±7.7 <LOQ TPhP 10±4 10±6 12±7.3 12±2.8 11±3.8 5.1±1.3 9.7±2.5 0.8±0.55 EHDPP 0.4±0.2 5.9±4.2 0.4±0.1 2.9±1.6 0.29±0.10 4.1±1.4 0.29±0.15 4.2±6.3
171
Figure A4.1. Averaged concentration of phthalates (a), HFRs (b), and OPEs (c) accumulated expressed as ng/dm2 BET-SSA of fabric. Error bars indicate standard deviation. Note: Y-axis uses a log scale for HFRs and OPEs but is linear for phthalates. * represents a significant difference between cotton and polyester (p<0.05). Note: TCiPP is referred as TCPP-1.
Chemical release to laundry water (group 2)
% 𝑅𝑒𝑙𝑒𝑎𝑠𝑒 = 𝐶𝑜𝑛𝑐𝑒𝑛𝑡𝑟𝑎𝑡𝑖𝑜𝑛 𝑜𝑓 𝑐ℎ𝑒𝑚𝑖𝑐𝑎𝑙𝑠 𝑖𝑛 𝑙𝑎𝑢𝑛𝑑𝑟𝑦 𝑤𝑎𝑡𝑒𝑟𝐶𝑜𝑛𝑐𝑒𝑛𝑡𝑟𝑎𝑡𝑖𝑜𝑛𝑠 𝑜𝑓 𝑐ℎ𝑒𝑚𝑖𝑐𝑎𝑙𝑠 ( 𝑖𝑛 𝑙𝑎𝑢𝑛𝑑𝑟𝑦 𝑤𝑎𝑡𝑒𝑟 + 𝑙𝑒𝑓𝑡 𝑜𝑛 𝑓𝑎𝑏𝑟𝑖𝑐)
× 100 ................(A4.1)
172
% 𝐿𝑒𝑓𝑡 𝑜𝑛 𝑓𝑎𝑏𝑟𝑖𝑐 = 𝐶𝑜𝑛𝑐𝑒𝑛𝑡𝑟𝑎𝑡𝑖𝑜𝑛 𝑜𝑓 𝑐ℎ𝑒𝑚𝑖𝑐𝑎𝑙𝑠 𝑙𝑒𝑓𝑡 𝑜𝑛 𝑓𝑎𝑏𝑟𝑖𝑐𝐶𝑜𝑛𝑐𝑒𝑛𝑡𝑟𝑎𝑡𝑖𝑜𝑛 𝑜𝑓 𝑐ℎ𝑒𝑚𝑖𝑐𝑎𝑙𝑠 (𝑖𝑛 𝑙𝑎𝑢𝑛𝑑𝑟𝑦 𝑤𝑎𝑡𝑒𝑟 + 𝑙𝑒𝑓𝑡 𝑜𝑛 𝑓𝑎𝑏𝑟𝑖𝑐)
× 100.......(A4.2)
Figure A4.2. Average concentrations of SVOCs released in laundry water (ng/L.dm2) and remaining on cotton (top) and polyester (bottom) (ng/dm2).
0.0001
0.01
1
100
10000 Cotton Released in laundry water Left on fabric
0.0001
0.01
1
100 Polyester
Ave
rage
con
cent
ratio
ns re
leas
ed to
laun
dry
wat
er
(ng/
L dm
2 fabr
ic) a
nd re
mai
ning
sorb
ed to
fabr
ic
(ng/
dm2 )
173
Figure A4.3. Difference in chemical accumulation, (Ccotton – Cpolyester)/Ccotton, normalized to planar surface area plotted against the (a) Henry Law constant (HLC, Pa-m3/mol), and (b) solubility (mg/L). TCEP, being an outlier, was excluded from solubility graph. In (a), green and purple ellipses indicate OPEs (except TCEP and TnBP) and HFRs, respectively, whereas remaining markers are phthalates. Red dotted line indicates zero on vertical axis.
Figure A4.4. Difference in chemical accumulation, (Ccotton – Cpolyester)/Ccotton, normalized to planar surface area, plotted against polarizability (latter values not available for all chemicals). Red dotted line indicates zero on vertical axis.
-0.60 -0.40 -0.20 0.00 0.20 0.40 0.60 0.80 1.00
1 1.2 1.4 1.6 1.8 2 2.2
Diff
eren
ce in
sorp
tion
cott
on
vs p
olye
ster
Polarizability
DnBP
BDEs
TPhP
TDCiPP
TCEP
174
Figure A4.5. Difference in chemical accumulation, (Ccotton – Cpolyester)/Ccotton, normalized to BET-SSA plotted against the (a) Henry Law constant (HLC, Pa-m3/mol), (b) solubility (mg/L) and (c) octanol-water partition coefficient (Log KOW). TCEP, being an outlier, excluded from solubility and Log KOW graphs. In (a), green and purple ellipses indicate OPEs (except TCEP and TnBP) and HFRs, respectively, whereas remaining markers are phthalates. Red dotted line indicates zero on vertical axis.
y = -1.4x + 3.4 r² = 0.59, p<0.001
-12
-10
-8
-6
-4
-2
0
2
2 4 6 8 10
Diff
eren
ce in
sorp
tion
cott
on
vs p
olye
ster
Log KOW
(c)
175
Figure A4.6. Percentage of accumulated chemical released to laundry water as a function of water solubility (mg/L). Black, green and purple ellipses indicate phthalates, OPEs and HFRs, respectively.
Figure A4.7. Percentage of accumulated chemical released to laundry water as a function of Henry’s law constant (HLC, Pa-m3/mol).
0%
20%
40%
60%
80%
100%
120%
1.00E-05 1.00E-03 1.00E-01 1.00E+01 1.00E+03
% r
elea
se it
o la
undr
y w
ater
Solubility
Cotton Polyester
EHDPP
TPhP DEHP
BzBP DnBP
OPEs (TnBP, TCEP, TCPP, TDCiPP)
HFRs
DiNP
0%
20%
40%
60%
80%
100%
120%
1.E-04 1.E-03 1.E-02 1.E-01 1.E+00 1.E+01
% r
elea
se to
laun
dry
wat
er
HLC
Cotton Polyester
TnBP
EHDPP
DnBP, DiBP
DEHP TPhP
TDCiPP, TCEP, TCPP
HFRs
BzBP
176
Figure A4.8. Percentage released of accumulated chemical to laundry water as a function of percentage in the gas phase measured by Saini et al. (Ch 2 and 4).
Figure A4.9. The difference in chemical accumulation, (Ccotton – Cpolyester)/Ccotton, normalized to BET-SSA plotted against the percentage released to laundry water. The dotted red line indicates zero on horizontal axis.
0%
20%
40%
60%
80%
100%
120%
20% 40% 60% 80% 100%
% r
elea
seto
laun
dry
wat
er
Gas-phase distribution
Cotton Polyester
HFRs
Phthalates
0%
20%
40%
60%
80%
100%
120%
-12.00 -10.00 -8.00 -6.00 -4.00 -2.00 0.00 2.00
% r
elea
sed
in la
undr
y w
ater
Difference
Cotton Polyester
TCEP
BzBP
DEHP
TPhP
EHDPP
DnBP
DiBP OPEs
DiNP HFRs
