The Occurrence of Bisphenol A, Phthalates, Parabens and Other Environmental Phenolic Compounds in House Dust: A Review

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2182 Current Organic Chemistry, 2014, 18, 2182-2199

The Occurrence of Bisphenol A, Phthalates, Parabens and Other Environmental Phenolic Compounds in House Dust: A Review

Wan-Li Ma

^{a, b}

, Bikram Subedi

^b

and Kurunthachalam Kannan

^a,b,c

*

aInternational Joint Research Center for Persistent Toxic Substances, State Key Laboratory of Urban Water Resource and Environ- ment, Harbin Institute of Technology, Harbin 150090, China; ^bWadsworth Center, New York State Department of Health, and Department of Environmental Health Sciences, School of Public Health, State University of New York at Albany, Empire State Plaza, P.O. Box 509, Albany, New York 12201-0509, United States; ^cBiochemistry Department, Faculty of Science and Experimental Biochemistry Unit, King Fahd Medical Research Center, King Abdulaziz University, Jeddah, Saudi Arabia

Abstract: Dust from indoor environments can contain significant amounts environmental contaminants and is an important source of human exposure to several toxicants. In this article, studies on the occurrence of several emerging environmental contaminants, namely bisphenol A (BPA), tetrabromobisphenol A (TBBPA), phthalates, parabens, and other environmental phenolic compounds in indoor dust from various countries, were reviewed. Issues associated with sampling of dust and the uncertainties introduced in the analytical proce- dures were also summarized. Finally, exposure to environmental phenolic compounds through dust ingestion was evaluated, and the contribution of indoor dust to the total daily exposure of toxicants was estimated. Overall, the reported concentrations of target chemicals in dust were found, in decreasing order, as phthalates (overall mean: 949 ± 669 μg/g, range: 0.9-10,900 μg/g) >>> nonylphenol (8.9 ± 6.8 μg/g, 2.6-29.2 μg/g) > BPA (3.6 ± 4.5 μg/g, 0.35-16.6 μg/g) > parabens (1.53 ± 0.52 μg/g, 0.03-125 μg/g) > pentachlorophenol (1.39 ± 2.31 μg/g, 0.050- 5.76 μg/g) > triclosan (0.65 ± 0.23 μg/g, 0.38-0.93 μg/g) > TBBPA (0.18 ± 0.14 μg/g, 0.049-0.505 μg/g). Despite the elevated levels of the target phenolic compounds reported in indoor dust, exposure of humans through dust ingestion was minor. Never- theless, dust can be a significant source of exposure to phenolic compounds for infants and toddlers. Elevated levels of phenolic compounds were found in dust collected from certain microenvironments such as offices and laboratories.

Keywords: BPA, environmental phenolic compounds, house dust, human exposure, phthalates.

1. INTRODUCTION

People spend most of their time (approximately 90%) indoors.

In the last few decades, the quality of indoor environments (indoor air and indoor dust) has received considerable attention among regulatory and public health agencies because of its significance in terms of public health. The quality of air that we breathe in our homes, schools, and offices is directly related to our health [1, 2].

Exposure to contaminants in indoor environments has been shown to elicit a variety of adverse health effects [3]. Poor indoor air quality can result from contaminants such as volatile organic compounds (VOCs) and industrial chemicals released by outgassing of building materials [4]. Further, the use of a wide range of chemicals in consumer products contributes to the contamination of the indoor environments. For example, introduction of several new chemicals in commerce and in consumer products contributes to the occurrence of these chemicals in indoor dust [5]. Indoor air and indoor dust are the most frequently used matrixes for the assessment of the quality of indoor environments [6-8].

For VOCs, measurements in indoor air provide a direct estimate of exposure levels [3]. However, episodic measurements of contaminants in indoor air cannot integrate exposures for a long period of time. Further, non-volatile chemicals tend to adsorb to dust particles [2]. Thus, indoor dust is a sink and a repository for many indoor environmental contaminants, and the contaminants in indoor dust can be considered as a marker of indoor exposure [3]. Indoor dust integrates contamination that occurs over a long period of time

*Address correspondence to this author at the Wadsworth Center, Empire State Plaza, P.O. Box 509, Albany, NY 12201-0509, USA; Tel: 1-518-474-0015;

Fax: 1-518-473-2895; E-mail: [email protected]

in the indoor environment, and thus, levels of contaminants in indoor dust are useful for retrospective exposure assessment [2].

The composition, methods of sampling and analysis for organic and inorganic contaminants (e.g., polybrominated diphenyl ethers [PBDEs], polychlorinated biphenyls [PCBs], polycyclic aromatic hydrocarbons [PAHs], pesticides, heavy metals) in dust, and human exposures through dust ingestion have been previously reviewed [2- 4, 6, 9, 10]. Two reviews have documented the occurrence of emerging environmental chemicals such as bisphenol A (BPA), phthalates, and phenolic contaminants in house dust [3, 4]. Many novel compounds that are widely used in building materials and consumer products are known to possess hormonally active properties [3, 11]. Some contaminants, such as BPA, are reported as endocrine disrupting chemicals (EDCs) [12-14]. Recent studies have shown the significance of house dust as a source of human exposure to EDCs [15-19].

The aim of this review is to provide a comprehensive summary of the available literature on the occurrence and human exposure of BPA, tetrabromobisphenol A (TBBPA), phthalates, parabens, and other environmental phenolic compounds such as nonylphenol, octylphenol, chlorophenols, bromophenols, triclosan (TCS), and benzophenone in indoor dust. Due to the wide range of physicochemical properties of the target compounds, each chemical class is described separately in this review. The structure, chemical formula, and select physicochemical properties of the target compounds are listed in Table 1.

2. INTRODUCTION OF TARGET COMPOUNDS 2.1. Bisphenol A

BPA (4,4´-dihydroxy-2,2-diphenylpropane) is an industrial chemical synthesized by condensation of two phenol groups and

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The Occurrence of Bisphenol A, Phthalates, Parabens and Other Environmental Phenolic Current Organic Chemistry, 2014, Vol. 18, No. 17 2183

Table 1. Structures and physicochemical properties of target compounds in this review.

Chemicals Abbreviation Molecular Structure Formula CAS Molecular Weight

Water Solubility^a

Log Koab

Log Kowc

bisphenol A BPA C15H16O2 80-05-7 228.29 172.7 12.747 3.64

bis(2-ethylhexyl) phtha-

late DEHP C24H38O4 117-81-7 390.56 1.132E-03 12.557 8.39

di-methyl phthalate DMP C10H10O4 131-11-3 194.18 2014 6.694 1.66

di-ethyl phthalate DEP C12H14O4 84-66-2 222.24 287.2 7.023 2.65

di-propyl phthalate DPP C14H18O4 131-16-8 250.29 37.99 8.053 3.63

di-n-butyl phthalate DBP C16H22O4 84-74-2 278.34 2.351 8.631 4.61

di-n-hexyl phthalate DNHP C20H30O4 84-75-3 334.45 0.012 9.799 6.57

di-n-octyl phthalate DNOP C24H38O4 117-84-0 390.56 4.236E-04 12.079 8.54

di-iso-butyl phthalate DiBP C16H22O4 84-69-5 278.34 5.061 8.412 4.46

di-iso-nonyl phthalate DiNP C₂₆H₄₂O₄ 28553-

12-0 418.61 2.317E-05 13.585 9.37

di-iso-decyl phthalate DiDP C28H46O4

26761-

40-0 446.66 2.239E-06 14.703 10.36

benzyl-butyl phthalate BBP C19H20O4 85-68-7 312.36 0.9489 9.018 4.84

di-cyclo-hexyl phthalate DCHP C20H26O4 84-61-7 330.42 0.04098 11.588 6.20

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Table 1. Contd…….

Chemicals Abbreviation Molecular Structure Formula CAS Molecular Weight

Log K_oa^b

Log K_ow^c

tetrabromobisphenol A TBBPA C15H12Br4O2 79-94-7 543.87 0.001 18.225 7.20

methyl paraben MeP C8H8O3 99-76-3 152.15 5981 8.791 1.96

ethyl paraben EtP C9H10O3 120-47-8 166.17 1894 9.178 2.49

propyl paraben PrP C10H12O3 94-13-3 180.08 529.3 9.624 2.98

butyl paraben BuP C11H14O3 94-26-8 194.23 159 10.032 3.47

benzyl paraben BzP C14H12O3 94-18-8 228.24 107.8 11.483 3.70

heptyl paraben HeP C14H20O3

1085-12-

7 236.30 8.0 10.922 4.94

4-hydroxybenzoic acid 4-HB C7H6O3 99-96-7 138.12 14500 10.915 1.39

triclosan TCS C₁₂H₇Cl₃O₂ 3380-34-

5 289.54 4.621 11.450 4.66

4-octylphenol 4-OP C₁₄H₂₂O 1806-26-

4 206.32 3.114 9.235 5.50

4-nonylphenol 4-NP C15H24O 104-40-5 220.35 1.57 8.617 5.99

2,4-dichlorophenol - C₆H₄Cl₂O 120-83-2 163.00 614.2 7.108 2.80

3,4-dichlorophenol - C6H4Cl2O 95-77-2 163.00 361.2 8.230 2.80

2,4,5-trichlorophenol - C6H3Cl3O 95-95-4 197.45 114.1 7.899 3.45

2,4,6-trichlorophenol - C6H3Cl3O 88-06-2 197.45 121 7.66 3.45

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Table 1. Contd…….

Chemicals Abbreviation Molecular Structure Formula CAS Molecular Weight

Log K_oa^b

Log K_ow^c

3,4,5-trichlorophenol - C6H3Cl3O 609-19-8 197.45 64.49 9.041 3.45

2,3,4,5-tetrachlorophenol - C6H2Cl4O 4901-51-3 231.89 28.69 9.371 4.09

2,3,4,6-tetrachlorophenol - C₆H₂Cl₄O 58-90-2 231.89 17.9 7.892 4.09

2,3,5,6-tetrachlorophenol - C₆H₂Cl₄O 935-95-5 231.89 54.9 9.041 4.09

pentachlorophenol PCP C6Cl5OH 87-86-5 266.34 3.09 11.119 4.74

2,4,6-tribromophenol - C6H3Br3O 118-79-6 330.80 9.127 9.968 4.18

4-hydroxybenzophenone 4-OH-BP C₁₃H₁₀O₂ 1137-42-4 198.22 405.8 11.153 2.67

2,4-

dihydroxybenzophenone 2,4-2OH-BP C13H10O3 131-56-6 214.22 413.4 11.925 2.96

2-hydroxy-4-

methoxybenzophenone BP-3 C14H12O3 131-57-7 228.24 68.56 10.002 3.52

2,2'-dihydroxy-4- methoxybenzophenone

2,2'-2OH-4-

MEO-BP C14H12O4 131-53-3 224.24 52.73 10.914 3.82

2,2',4,4'- tetrahydroxybenzophenone

2,2',4,4'-4OH-

BP C13H10O5 131-55-5 246.22 398.5 16.611 2.78

a Water solubility (mg/L, 25^oC) estimated from Log Kow using the US Environmental Protection Agency’s EPISuite™, [WSKOWWIN v1.41];

b Log octanol-air partition coefficient (25 ^oC) estimated using the US Environmental Protection Agency’s EPISuite™, [KOAWIN v1.10];

c Log octanol-water partition coefficient (25 ^oC) estimated using the US Environmental Protection Agency’s EPISuite™, [KOWWIN v1.67].

one acetone molecule [20]. BPA is used primarily as an intermedi- ary in the production of polycarbonate plastics and epoxy resins [21, 22], which are widely used in consumer products, including feeding bottles, adhesives, protective coatings, powder paints, automotive lenses, protective window glazing, dental fillings, com- pact disks, optical lenses, and thermal receipt papers [23-25]. BPA is a weak estrogen receptor agonist. Emerging evidence suggests that BPA can influence multiple endocrine pathways [20, 26, 27].

2.2. Phthalates

Phthalates (phthalic acid esters) are dialkyl or aryl alkyl esters of 1,2 benzene dicarboxylate [28] and have a broad range of appli- cations in industry and commerce [29]. Phthalates are used mainly as plasticizers and stabilizers in food processing and medical appli- cations, personal care products, building materials, household furnishings, nutritional supplements, toys, and insecticides [29-32].

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Phthalates can enter the environment through manufacturing proc- esses and leaching from consumer products [24]. Epidemiological studies have found associations between exposure to phthalates and reproductive toxicity, asthma/allergies, and hepatotoxicity [33-35].

Kolarik et al. (2008) reported a significant association between wheezing among preschool children and urinary concentration of di-2-ethylhexyl phthalate (DEHP) [34]. The health risks of phthalates are still unclear and debatable [13], but there is unequivocal evidence that humans are exposed to high levels of phthalates on a daily basis, and urinary concentrations can range from several tens to hundreds of nanograms per milliliter [36].

2.3. Tetrabromobisphenol A

TBBPA is a phenolic and hydrophobic compound, which is used primarily as a reactive flame retardant in epoxy and polycarbonate resins [37]. The industrial production process involves bro- mination of BPA in the presence of a solvent, such as methanol, 50% hydrobromic acid, or aqueous alkyl monoethers [38]. TBBPA is the most widely used brominated flame retardant in epoxy resin printed circuit boards and acrylonitrile-butadiene-styrene plastics [39]. TBBPA has a low acute toxicity in humans but is toxic to aquatic organisms [40]. Rodent exposure study indicated that TBBPA was both a thyroid hormone and an estrogen agonist [38].

2.4. Parabens

Parabens are esters of para-hydroxybenzoic acid and are widely used singly, or in combination of several homologues, as broad spectrum antimicrobial preservatives in foods, cosmetics, and pharmaceutical products [41, 42]. Six commonly known parabens are methyl-paraben (MeP), ethyl-paraben (EtP), propyl-paraben (PrP), butyl-paraben (BuP), heptyl-paraben (HeP) and benzyl- paraben (BzP). Laboratory animal studies have shown that parabens can elicit estrogenic activity [43-47].

2.5. Other Phenolic Compounds

Other target phenolic compounds considered in this review are triclosan (TCS), 4-octylphenol (OP), 4-nonylphenol (NP), chlorophenols (di-, tri-, tetra- and penta- or PCP), tribromophenol, benzotriazoles (BTRs), benzothiazoles (BTHs), and benzophenones.

These phenolic compounds are widely used in building materials and consumer products, including household cleaners and deter- gents (e.g., alkylphenols, benzotriazoles), paints, paper coatings, corrosion inhibitors (e.g., benzothiazoles), biocides (e.g., TCS), and wood preservatives [4, 48]. These phenolic compounds have been found at high levels in indoor dust and in samples of human serum and urine [48-51].

3. HOUSE DUST SAMPLING METHODS

Indoor dust, in general, consists of inorganic and organic matter, and the relative proportions of these components vary consid- erably. Indoor dust varies greatly in composition depending on the season, ventilation, building characteristics, and the materials used in the building. The “true” concentration of contaminants in indoor dust is difficult to obtain due to the heterogeneous and complex nature of the matrix. To achieve homogeneity and comparability of results between studies, it is important to collect a representative fraction of dust, and the concentration can be dependent on the sampling method. Further, standard methods for the collection of indoor dust are not available, and the optimal method can depend on the surface to be sampled and the goal of the study [9]. A comprehensive description as well as the advantages and disadvantages

of different dust sampling methods and strategies can be found in earlier reviews [3, 4, 52]. In general, indoor dust can be collected by passive and active sampling methods. Passive sampling is performed using beakers or non-electrostatic plates that are placed in a stationary position and that allow the dust to accumulate on the surface. This method requires a long time to obtain a sufficient quantity of dust, thus, this method is rarely used [3, 4]. Active sampling of dust includes the use of vacuum cleaners, surface wiping, press sampling, or sweeping/brushing [3]. The advantage of the active sampling method is its cost effectiveness and that this method can integrate contamination in several rooms/areas over a specific period of time [53].

Two metrics have been used in the determination of contami- nant levels in dust. The first is the loading of contaminants on a surface in units of micrograms per square centimeter of the surface per unit time, and the second is the “concentration of contaminants in the collected dust” in units of micrograms per gram [52]. The former is usually used for the passive sampling method and the latter for the active sampling method. An overview of the sampling methods used in the analysis of the select target compounds of this review is presented (See details in Table S1 of Supporting Informa- tion). Except for some Asian countries, where house dust samples were collected by sweeping the floors and furniture surfaces with a brush [16, 54], the most common method of dust sampling was through use of a vacuum cleaner in several other countries. Collec- tion of dust by a vacuum cleaner can permit compositing of samples from several rooms in a house and can eliminate the need for an in- home visit by the investigator, thereby minimizing the invasiveness of home sampling [2]. In addition to household vacuum cleaners, some commercial vacuum cleaners were also used in dust sampling [39, 55-58]. For example, a high-volume small-surface sampler (HVS3), which is a modified vacuum cleaner for the collection of particles greater than 5 m using various cyclones, has been rec- ommended by the American Society for Testing and Materials (ASTM) [59].

To avoid contamination from vacuum cleaners during sampling, prior to each use, the vacuum’s hose and nozzle assemblies are cleaned. For phthalates, phthalate-free materials were used during sampling [60], and sampling on plastic surfaces and textiles was avoided [61]. House dust was collected primarily by study partici- pants, residents, and volunteers with conventional vacuum cleaners, whereas trained field staff were involved in sampling when commercial vacuum cleaners were used [18]. In most of the studies discussed in this review, the vacuum cleaners were fitted with cellu- lose filters, paper bags, and nylon socks to collect the dust [62-64].

In some studies, filters were cleaned in a Soxhlet apparatus with a hexane-dichloromethane mixture prior to sampling [65]. In addition, the vacuum cleaner bags were changed after each sample collection [66].

The sampling procedure used in some studies involved the collection of “fresh settled dust” and “old dust” concurrently. In general, ‘‘old dust’’ is expected to contain high levels of contaminants [67]. Fan et al. (2010) compared two sampling methods for the determination of parabens and triclosan in dust: “fresh” or “active”

dust (FD) collected using a Pullman Holt vacuum sampler and “old dust” (HD) from a household vacuum cleaner. They found that the concentrations of chemicals in HD samples were higher than those in FD samples [68].

Depending on the study objectives, specific protocols can be established for dust sampling, which include height, area, and time of sampling. For sampling at different heights, dust was collected from

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the tops of bookshelves, cupboards, desks, and/or casings of win- dows and doors, at least 0.8 m above the floor, in a previous study [63]. There is no consensus on the sampling area and length needed to be vacuumed and as such there are wide variations in the literature. In regard to the sampling area, D'Hollander et al. (2010) established a standard protocol for houses (20 or 24 m²), offices (10 m²), living rooms (8 m²), bedrooms (8 m²), kitchens (4 m²), and work areas (4 m²) [69]. However, Geens et al. (2009) reported that house dust was collected from the living room (8 m²), bedroom (4 m²), and kitchen (4 m²) [64]. Dust samples were also collected from air- conditioner filters or from the inside of electronic devices [66, 70].

In regard to the sampling time, Abdallah et al. (2008) established a protocol for 1 m² area of carpet wit h2 min and 4 m²concrete floors with 4 min [39]. However, Nilsson et al. (2005) suggested that dust sampling should be performed until the amount of dust collected was sufficient for analysis [71].

4. HOUSE DUST TREATMENT AND ANALYSIS

The treatment, extraction, and purification (clean-up) methods applied in the analysis of each class of target compounds in dust are presented in Table S2-S6 (SI), and a brief summary of the methods is presented in Table 2. Usually, a fine fraction of the indoor dust is used for chemical analysis (with an aerodynamic diameter <500 m) because the fine fraction is inhalable by humans and can repre- sent a source of human exposure [72]. Further, the fine fraction adsorbs significant quantities of organic contaminants [72]. Human exposure varies with the sizes of the particulate matter [4]. For example, Cao et al. (2012) reported that human exposure to toxic chemicals varied by over 10-fold between different size fractions of dust [73]. The size fraction of dust used in analysis varied among studies and was <63 m, <75 m, <80 m, <100 m, <150 m,

<250 m, <300 m, <425 m, <500 m, <2 mm (Table 2). Quan- tity and homogeneity are important factors to be considered in the analysis of contaminants in dust [4]. A size fraction of 63m was suggested for dust analysis because this fraction was free of sand/soil minerals and enriched with organic contaminants [3].

Prior to extraction, surrogate and/or internal standards were added to the dust sample for the evaluation of extraction efficiency

and method performance [74]. The spiked samples were allowed to equilibrate at room temperature before extraction [16, 61]. The most widely applied extraction method is sonication/ultrasonica- tion, followed by solid-liquid and liquid-liquid extraction (Table 2).

Soxhlet extraction and pressurized liquid extraction were also used.

House dust was mostly extracted with organic solvents, individually or in combination. The commonly used solvents include methanol, acetone, dichloromethane, hexane, toluene, diethyl ether, and/or ethyl acetate. In some studies, water was also used for the extraction of organic chemicals through pressurized hot water extraction [47].

Following extraction, various purification steps, including solid phase extraction (SPE) with adsorbent packed cartridges (e.g., Florisil SPE cartridge, Oasis MCX cartridge) and chromatographic gravity columns that involved silica gel and alumina, were used.

The most common detection techniques employed in the analysis of the target compounds in dust were gas chromatography (GC) with mass spectrometry (MS), flame ionization detector (FID), electron capture detector (ECD), and UV spectrometry. Aside from GC, liquid chromatography-tandem mass spectrometry (LC-MS/MS) was also commonly used in the analysis of several phenolic compounds such as BPA, TBBPA, parabens, chlorophenols, BTRs, BTHs, benzophenones, and TCS.

5. OCCURRENCE OF ENVIRONEMTAL PHENOLIC COMPOUNDS IN HOUSE DUST

5.1. BPA

Given the widespread use of BPA in consumer products [75, 76], elevated levels found in indoor dust are expected (See details in Table 3 [48, 56, 57, 60, 64, 70, 77-79]). BPA concentrations of up to ~10 000 ng/g were found in dust samples from Belgium [64].

BPA concentrations in house dust from Japan (mean: 3720 ng/g) and Korea (2210 ng/g) were similar to those from Belgium (2000 ng/g) and 3-5 times higher than those from the US (500-600 ng/g), China (347 ng/g), and Germany (661 ng/g) [64, 70, 77, 78]. In the US, two studies reported the mean BPA concentrations of 1520 and 1650 ng/g in dust samples collected from the states of North Caro- lina and Massachusetts, respectively [56, 60].

Table 2. Summary of treatment and analysis methods for phenolic compounds in house dust.

Compounds Pretreatment Extraction Method Extraction Solvent Clean-up and Final

Treatment Detector

BPA

sieved to 63 m, 150 m, 425 m, 500 m,

2 mm

sonicate/ultrasonicate, solid-liquid

methanol, water, dichloromethane, hexane, acetic acid, diethyl ether,

acetone, ethyl acetate

distilled water, Florisil SPE cartridge, Oasis MCX cartridge, nylon filter

GC-MS;

LC-MS/MS

Phthalates

sieved to 63 m, 100 m, 150 m, 250 m, 300 m, 500 m, 2 mm

sonicate/ultrasonicate, solid-liquid, Soxhlet, accelerated solvent, pressur-

ized liquid (fluid), solid phase micro extraction

methanol, diethyl ether, hexane, acetone, toluene, dichloromethane,

ethyl acetate, cyclohexane car- boxen/polymethylsilyl adsorbent

Florisil SPE cartridge, silica column, alumina column,

filtrated

GC/GC-MS;

LC-MS/MS

TBBPA sieved to 63 m, 150 m, 500 m

sonicate/ultrasonicate, liquid-liquid, Soxhlet, pressurized liquid (fluid)

hexane, acetone, toluene, dichloromethane,

silica column, GPC column, Florisil SPE cartridge, nylon

filter

GC-HRMS;

LC-MS/MS

Parabens

sieved to 60 m, 75 m, 80 m, 100 m, 150 m,

2 mm

sonicate, solid-liquid, the matrix solid phase dispersion, pressurized

liquid

acetonitrile, ethyl acetate, ultrapure and/or Milli-Q water, methanol

filtrated and derivatized, thermal desorption, SPE

cartridge

GC-MS;

LC-MS/MS

Other phe-

nols sieved to 150 m, 2 mm sonicate, solid-liquid, accelerated solvent

methanol, water, dichloromethane, diethyl ether, hexane, acetone

water wash, derivatized, Florisil SPE cartridge, Oasis

MCX cartridge

GC-MS;

LC-MS/MS

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Several factors can affect the concentrations of BPA in house dust (including floor type, room furnishings, and ventilation).

Higher concentrations were generally found in dust from offices and laboratories than in homes. The highest concentrations of BPA were found in office dust collected from Japan and Korea (Table 3).

Liao et al. (2012) reported that in Korea, BPA concentrations in dust collected from offices were similar to those from laboratories, but they were significantly higher than those in homes [77]. Simi- larly, Geens et al. (2009) found 5- to 10-fold higher concentrations of BPA in dust samples collected from offices than those from homes [64]. Studies also have reported the occurrence of BPA in daycare centers, suggesting the exposure of children to BPA from such facilities [48, 56, 79]. As discussed above, the wide variation in BPA concentrations reported between studies can be related to the size fraction of the dust used in the analysis. Studies have used dust fractions ranging in size from 63 m to 2 mm. Thus, caution should be exercised in the comparison of concentrations between studies.

5.2. Phthalates

More than 10 phthalate esters are used in commerce, and the US Environmental Protection Agency (EPA) has identified 8 as

environmental and human health concerns. A summary of phthalate concentrations reported in indoor dust from several countries and the global distribution of selected phthalates in indoor dust are presented in Table 4 [16, 17, 31, 32, 55-57, 60-63, 66, 71, 74, 80-88]

and Fig. 1, respectively. Overall, phthalates were found in dust from houses, apartments, daycare centers, offices, schools, hospi- tals, and shopping malls worldwide. The commonly reported phthalates in house dust were dimethyl phthalate (DMP), diethyl phthalate (DEP), di-n-butyl phthalate (DBP), butyl benzyl phthalate (BBP), bis(2-ethylhexyl) phthalate (DEHP), di-n-octyl phthalate (DNOP), and di-iso-nonyl phthalate (DiNP). In addition, occur- rences of di-methyl-propyl phthalate (DMPP), di-n-propyl phthalate (DNPP), di-n-hexyl phthalate (DNHP), di-cyclo-hexyl phthalate (DCHP), and other phthalate esters containing substituted branched alkyl groups, such as di-iso-butyl phthalate (DiBP) and di-iso-decyl phthalates (DiDP), have also been reported in dust.

DEHP was the major phthalate in indoor dust. Langer et al.

(2010) reported that concentrations of DEHP in dust were an order of magnitude higher than those of other phthalate esters in dust from daycare centers in the Island of Fyn, Denmark [61]. The concentrations of DEHP in dust from school buildings were ~6 times higher than those reported for daycare centers in Denmark [61, 86].

Table 3. Summary of BPA concentrations (ng/g) reported in house dust from several countries. DR= Detection rate; MDL = Method detection limit;

N/A= Not available; NY= New York; KY = Kentucky

Site Location Sample Size DR (%) Mean Median Range Reference

North Carolina, US home 119 25 N/A <MDL <MDL-707 [48]

Ohio, US home 116 47 N/A <MDL <MDL-589 [48]

North Carolina, US home 9 N/A 1520 - 707-1890 [56]

Flanders, Belgium home 18 100 2001 1461 535-9729 [64]

Murray, KY, US home 7 100 520 242 172-2130 [70]

Albany, NY, US home 28 93 620 701 <0.5-1690 [70]

Albany, NY, US home 9 100 836 881 135-2320 [70]

Four cities, China home 19 89 347 75 ND-2550 [77]

Five cities, Japan home 20 100 3720 2270 496-12300 [77]

Two cites, Korea home 16 100 2210 2040 980-4190 [77]

Massachusetts, US home 118 86 1650 821 <MDL-17600 [60]

Bavaria, Germany home 12 100 661 553 117-1486 [78]

Flanders, Belgium office 2 100 6533 6533 4685-8380 [64]

Three cities, China office 7 100 1220 787 117-3490 [77]

Two cities, Japan office 2 100 16600 16600 11400-21800 [77]

Two cities, Korea office 14 100 13200 8540 2310-39100 [77]

Massachusetts, US home and office 6 50 393 - 250-480 [57]

North Carolina, US daycare center 19 53 - 30.8 <MDL-156 [48]

Ohio, US daycare center 23 70 - 28.3 <MDL-123 [48]

North Carolina, US daycare center 4 - 1950 - 567-3260 [56]

North Carolina, US daycare center - - 2260 - 1040-4510 [79]

Murray, KY, US laboratory 5 100 1280 1140 445-2950 [70]

Albany, NY, US laboratory 1 100 10200 - - [70]

Three cities, China laboratory 6 100 1680 732 57-5540 [77]

Two cities, Korea laboratory 11 100 6400 4430 1070-25900 [77]

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The Occurrence of Bisphenol A, Phthalates, Parabens and Other Environmental Phenolic Current Organic Chemistry, 2014, Vol. 18, No. 17 2189

Table 4. Summary of phthalates concentrations (g/g) reported in house dust from several countries.

Sites DMP DEP DiBP DBP BBP DEHP DOP/NP/DP Ref.

US - 2.15^a (1.01-3.58)

1.32^a (1.05-2.05)

27.4^a (11.1-59.4)

117^a (12.1-524)

315^a (69.4-524)

- [57]

Massachusetts, US -

4.98^b (up to 111)

1.91^b (up to 39.1)

20.1^b 352

45.4^b (3.87-1310)

340^b (16.7-7700)

- [60]

North Carolina, US - - -

1.87^a (0.058-5.85) 1.21^a (0.384-3.03)

3.72^a (0.022-7.43) 5.86^a (0.496-15.6)

- - [56]

California, US

- - - - 50-1290 104-2050 - [74]

Albany, New York US

0.08^b (up to 3.3)

2^b (0.7-11.8)

3.8^b (0.7-34.4)

13.1^b (4.5-94.5)

21.1^b (3.6-393)

304^b (37.2-9650)

0.4^b,c (up to 14.1)

China 0.2^b

(up to 8.2)

0.4^b (up to 45.5)

17.2^b (2.6-299)

20.1^b (1.5-1160)

0.2^b (up to 12)

228^b (9.9-8400)

0.2^b,c (up to 45.7)

[16]

Guangzhou, China

up to 2.18 (0.038-4.54)

up to 1.76 (0.03-6.78)

up to 57.6 (7.04-165)

up to 77.6 (11.1-210)

up to 2.2 ( up to 4.07)

up to 1429 (100-2837)

up to1.01 (up to 6.84)

[80]

Several sites, China

0.40^b (0.2-0.62) 0.24^b (0.02-0.34) 0.43^b (0.07-3.35) 1.33^b (0.15-3.67) 0.31^b (0.05-25.4) 1.49^b (0.82-6.35) 0.05^b (up to 0.55)

2.17^b (0.83-6.64) 2.49^b (1.0-3.15) 1.06^b (0.27-1.81) 1.69^b (0.46-6.99) 1.69^b (1.32-2.81) 2.32^b (1.33-35.6) 1.50^b (0.03-13.8)

19.8^b (17.7-62.5) 40.4^b (24.2-107) 24.7^b (5.11-113) 32.3^b (13.4-79.2) 57.1^b (16.5-78.9) 30.9^b (19.1-50.8) 34.1^b (0.63-401)

55.6^b (52-78.6) 82^b (63.6-109) 51.79^b (17.8-88.9)

69.2^b (26.7-138) 51.8^b (42-73.7) 82.4^b (58.6-133) 77^b (3.11-878)

10.70^b (3.32-26.1) 23.6^b (8.18-33.4) 10.6^b (4.93-328) 14.7^b (2.13-175) 10.1^b (4.58-32.8) 24.2^b (10.7-284) 4.63^b (up to 157)

597^b (286-799) 918^b (277-1450) 707^b (165-1020) 721^b (82.3-1490) 819^b (372-952) 958^b (9029-1050) 1190^b (175-8680)

2.09^b (0.67-10.4)^b,d 5.27^b (0.16-5.74)^b,d 2.70^b (0.39-10.5)^b,d 3.47^b (0.17-22)^b,d 3.44^b (1.10-5.40)^b,d 6.49^b (1.77-24.6)^b,d 2.90^b (0.16-63.3)^b,d

[66]

Nanjing, China

0.4^a (up to 24)

0.9^a (up to 33.9)

-

52.3^a (up to 2150)

2.9^a (up to 38.7)

462^a (0.3-9950)

1.6^a,c (up to 39.5)^c

[62]

multi-surface dust (up to 1.01)

0.35^b (up to 6.3)

2.4^b (0.5-21.8)

22.3^b (5.1-549)

2.4^b ( up to 35.8)

1200^b (220-10,200)

- Sapporo,

Japan

floor dust (up to 4.9)

0.33^b (up to 1.9)

2.9^b (0.6-31.1)

19.8^b (1.8-1476)

4.2^b (up to 52.1)

880^b (98.2-5850)

-

[81]

Kuwait

0.03^b (up to 0.1)

1.8^b (0.1-16)

-

45^b (8.3-160)

8.6^b (up to 160)

2256^b (380-7800)

- [82]

Taiwan

0.1^b (0.1-1.0)

1^b (1.0-1.0)

-

20.2^b (13.3-39.8)

1.0^b (1.0-3.9)

753^b (487-1315)

- [31]

Halle/Saale, Germany - - - 87.4^b 15.2^b 604^b 162.6^b,e [83]

Steglitz, Germany

10.8^a (up to 158)

44.6^a (up to 632)

-

55.6^a (up to 141)

86.1^a (up to 816)

775.5^a (up to 1763)

- [17]

Berlin, Germany

- - - - -

508^f (22-5330)

- [84]

Stockholm, Sweden

0.1â 0.3â 0.4â

11â 6.9â 37â

6â 9.1â 34â

130â 190â 150â

31â 47â 19â

980â 2000â 1500â

- [63]

Värmland, Sweden - 31â 97â 226â 319â 1310â - [85]

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Table 4. Contd……

Sites DMP DEP DiBP DBP BBP DEHP DOP/NP/DP Ref.

Sweden - 10^a (0.1-100)

- - - - - [71]

bedrooms 3.1^f 16.6^f 8.1^f 4.2^f 220^f -

Island of Fyn, Denmark

daycare centers 1.9^f 18.1^f 30^f 16.4^f 540^f -

[61]

Denmark - - - - - 3214^a - [86]

Austria - - - - - 790-3000 - [87]

Burgas, Bulgaria

260^f (210-320)

350^f (290-420)

-

7860^f (6590-9360)

320^f (280-380)

960^f (790-1170)

250^f (200-300)

[32]

Oslo, Norway

sedimented dust suspended particulates

organic fractions

10â (0-110) 80â (0-240) 10â (0-170)

10^a (0-300) - 10^a (0-450)

100â (10-1030) 370â (103-690) 120â (10 -1170)

110â (0-440) 140â (0-750) 140â (0-480)

640â (100-1610) 600â (240-940) 820â (110-2100)

100^a (up to 1380)^d - 120^a (0-1610)

[55]

UK Finland Denmark Sweden France Spain

0.12^a (up to 1.1) 0.4-2.2

- - - 0.4

12.2^a (0.6-115) 2-136.6 0.7-1.5 2.5 & 20.3

43.6 9.5

52^a (0.2-157.4) 6.1-25.3 6.1-13.2 10.8 & 31

68.4 37.6

50.2^a (0.1-106.4) 37.8-140.9

8.5-79 21.9 & 102

22.1 119.9

56.5^a (up to 238.9) 27-38.5 13.6-67.1 60.2 & 97.4

9.3 141.8

191.5^a (0.5-416.4) 148-579.3 45.5-183.6 207 & 239.2

185.4 194.4

69.3^a,e (up to 494) 4.3-248.2

- 88.9 & 71.1

312.4 117.8

[88]

amean.

bmedian.

cDOP.

dsum of DNP and DiDP.

esum of DiNP and DiDP.

fgeometric mean.

DEHP accounted for 24-92% of the total phthalate concentrations in dust from Kuwait [82], Germany [83], Norway [55], the UK, Finland, Denmark, France, and Spain [88]. It was reported that DEHP concentrations were 2-4 orders of magnitude higher than the concentrations of other phthalates in dust from homes in Japan [81], and 1-3 orders of magnitude higher than those of other phthalates in homes in China and the US [16, 62, 80]. Hutter et al. (2006) reported that dust samples from a new office building contained up to

~3% DEHP by weight [87]. Overall, DEHP was found in all dust samples (detection frequencies of ~100%) in all studies worldwide.

The high concentrations of DEHP reported in most of these studies are due to its high production volume (~3.5 million metric tons per year globally) and usage (~30% by weight in PVC) [89].

In addition to DEHP, other frequently reported phthalate esters in indoor dust were DBP, DiBP, and BBP, which were found at higher concentrations than those of the relatively more volatile DMP and DEP. In some countries, DBP was the major phthalate found in house dust. For example, dust samples from Bulgaria were dominated by DBP (geometric mean concentration: 7860 g/g) [32]. The concentrations of DEHP were followed by those of DBP in dust from homes in Asian countries [16, 62, 66, 80]. The concentrations of DEHP in dust from European countries, however, were followed by those of DBP and BBP [17, 55, 63, 85]. The variation in the profiles of phthalate concentrations in dust from different

countries can be attributed to the different usage patterns of phthalates in consumer products.

The volatile esters, DMP and DEP, were reported less frequently and/or at lower concentrations than those of other phthalate esters in dust. DMP is used in plastics, rubber coating agents, insect repellants, and pesticides. DEP is used in many commercial and consumer products such as fragrances, nail polishes, hair care products, adhesives and sealants, rubber and plastic products, and soaps.

In the US, DMP was reported at a mean concentration of 0.08 g/g, and DEP at 3.04 g/g [16, 57, 60]. The average concentration of DMP in dust from homes in Asian countries was 0.56 g/g and that for DEP was 1.20 g/g [16, 31, 62, 66, 81, 82]. In European countries, the average concentration of DMP in dust was 2.9 g/g and, for DEP, was 18.2 g/g [17, 35, 61, 63]. The highest concentrations of DMP and DEP in house dust were found in Bulgaria (260 and 350g/g, respectively) [32].

Occurrence of octyl-, nonyl-, decyl-phthalates and other branched isomers has also been reported in indoor dust. DNHP (up to 11.4 g/g), DCHP (up to 0.3 g/g), and DNOP (up to 45.7 g/g) were reported in indoor dust from China and the US [16]. DMPP (up to 161.3 g/g) was reported in dust from Germany [17]. DiNP was a dominant compound (1, 312.4 g/g) in house dust from France [88]. DNHP (up to 30.6 g/g), DCHP (up to 62.7 g/g), and

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bis-(2-ehtylhexyl) adipate (up to 391 g/g) were also reported in house dust from the US [57, 60].

Phthalate concentrations in indoor dust have been correlated with the types of building materials and/or consumer products.

Bornehag et al. (2004) reported that dust collected from bedrooms with PVC floorings contained higher concentrations (p < 0.001) of DEHP and BBP than those from bedrooms without PVC floorings [35]. However, the concentrations of other phthalate esters in dust were not correlated with PVC floorings [35]. Zhang et al. (2013) reported that concentrations of DBP, BBP, and DNOP in dust from houses with solid-wood flooring were significantly higher (p < 0.05) than concentrations in houses without solid-wood flooring [62]. However, some studies did not find any correlations between phthalate concentrations in dust and PVC flooring [32], carpet [83], or floor coatings [87].

Zhang et al. (2013) reported that concentrations of DEP in dust collected from houses where children lived with their grandparents were significantly lower (p < 0.01) than those in dust from the houses where children lived with their young parents (0.31 ± 0.004 g/g vs. 0.11 ± 0.005 g/g) [62]. The difference was attributed to the use of large amounts of DEP-containing products, such as fragrances, nail polishes, deodorants, lotions, skin cleaners, body products, and hair products, by younger parents [62]. Kolarik et al.

(2008) did not find any significant relationship between the concentrations of phthalates in indoor dust and temperature or relative humidity [32]. Fromme et al. (2004) found elevated concentration of DBP in dust and related that to poor air exchange rate in a room [17].

Exposure of children to phthalates is of great concern due to the potential health (reproductive) effects. Several countries (including the US) have banned the use of phthalates in children’s products, such as toys. The concentrations of DBP and BBP in indoor dust from daycare centers in the US were ~6.6 and ~10.5 times, respectively, lower than those found in dust from homes [16, 56, 57, 60, 74]. However, in Sweden, mean concentrations of DMP, DBP, DiBP, BBP, and DEHP in dust from children’s bedrooms and daycare centers were 1.2 to 7.3 times higher than the concentrations measured in homes/offices [63, 85]. Similarly, in Denmark, mean concentrations of DBP, DiBP, BBP, and DEHP in dust from daycare centers were 1.1 to 3.9 times higher than those found in children’s bedrooms; however, the mean DEP concentration was ~1.6 times higher in dust from children’s bedrooms than daycare centers [61].

5.3. TBBPA

Concentrations of TBBPA in indoor dust are much lower than those reported for BPA (See Table 5). In general, concentrations of TBBPA in house dust were below 500 ng/g, which were approximately an order of magnitude lower than BPA concentrations.

Geens et al. (2009) found no correlation between TBBPA and BPA concentrations in dust samples [64]. Most studies have reported mean TBBPA concentrations below 200 ng/g in house dust (Table 5) [18, 39, 40, 58, 64, 65, 69, 90]. However, Takigami et al. (2009) reported that concentrations of up to500 ng/g in house dust from Japan [90]. Two studies reported the concentrations of TBBPA in office dust [39, 64], which were similar to those in home dust. Har- rad et al. (2010) reported that the concentrations of TBBPA in dust from schools and daycare centers were higher than those in homes Fig. (1). Global distribution of concentrations of select phthalates in house dust (g/g).

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[58]. Abdallah et al. (2008) reported that concentrations of TBBPA in dust from pubs and restaurants were higher than those in homes and offices [39]. Limited dust samples analyzed in some studies (N = 2 to 45) preclude drawing further conclusions.

5.4. Parabens

Limited data are available in regard to paraben concentrations in house dust [47, 60, 68, 91, 92]. Several homologues of parabens are used in commerce, and the most widely studied are MeP, EtP, PrP, BuP, and BzP. MeP and PrP were the predominant paraben analogues found in house dust, with a detection rate of 100%. It is expected since MeP and PrP are the most commonly used antimicrobial preservatives in consumer products [68, 93]. The reported concentrations of MeP and PrP, overall, ranged from 226 to 1670 ng/g and from 123 to 761 ng/g, respectively (See Table 6) [47, 60, 68, 91, 92, 94]. Concentrations of EtP, BuP, and BzP were 1-2 orders of magnitude lower than those of MeP and PrP. Among several countries, no significant difference was observed for paraben concentrations in dust, indicating a comparable degree of contamination in indoor dust worldwide.

5.5. Other Phenolic Compounds

The mean PCP concentration in dust from childcare centers in the US was ~87 ng/g (maximum: 712 ng/g) (See Table 7) [19, 48, 56, 57, 60, 67, 68, 71, 79, 81, 88, 91, 94-99]. PCP concentrations in dust from homes (135 ng/g) were similar to those for childcare

centers in the US [56]. PCP concentrations in house dust from the US (576 ng/g) were ~2 times higher than those reported from Ger- many and ~5760 times higher than those reported from Japan [57, 67, 95]. Similarly, tetrachlorophenols (2,3,4,5-tetrachlorophenol, 2,3,5,6-tetrachlorophenol, and 2,3,4,6-tetrachlorophenol), trichloro- phenols (2,4,5-trichlorophenol, 2,4,6-trichlorophenol, and 3,4,5-trichlorophenol), and tribromophenols have been reported in dust from homes and offices in Japan at concentrations of up to 79, 1600, and 620 ng/g, respectively [95]. Rudel et al. (2003) reported some other substituted phenols in indoor dust from the US: 2,4-dichlorophenol, 4-nitrophenol, 4-t-butylpenol, 3-biphenylol, 4,4-bi- phenyldiol, 4,4’-methylenediphenol, 4-cumylphenol, and p-phenyl- phenol, at concentrations of up to 3890 ng/g [60]. The mean concentration of TCS in house dust from Spain (820 ng/g) was 2 times higher than that from Canada [68, 91, 94].

Alkylphenols and their ethoxylates are high-production volume chemicals and are widely distributed in the environment (Table 7).

The mean concentration of 4-n-nonylphenol (NP) in dust from childcare centers was 18.8 g/g, which was higher than that found in homes (4.69 g/g) in the US [56, 57, 60, 79]. The mean NP concentration in dust from the US was similar to that reported from Japan (3.7 g/g) but 2 times lower than that reported from Euro- pean countries [81, 88]. Rudel et al. (2003) reported that the concentration of NP ethoxylates were up to 49.3 g/g, while 4-n-octylphenol (OP) and its ethoxylates were at the concentrations of up to 2.12 g/g in house dust in the US [60].

Table 5. Summary of TBBPA concentrations (ng/g) reported in house dust from several countries.

Site House Type Sample Size DR (%) Mean Median Range Reference

West Midlands,

UK home 35 97 87 62 <MQL-382 [39]

California, US home 16 94 NA 260 <10-3400 [18]

California, US home 16 100 NA 200 22-2000 [18]

Germany & US home 26 77 86 48 ND-470 [40]

Flanders, Belgium

home 18 100 146 10 0.85-1481 [64]

Hokkaido, Japan

home 2 100 505 505 490-520 [90]

Flanders,

Belgium home 45 NA ^b NA 12 <3-419 [69]

West Midlands, UK

office 28 86 49 36 <MQL-140 [39]

Flanders, Belgium

office 2 100 73 73 45-100 [64]

West Midlands, UK

primary school and daycare center

classrooms

43 100 200 110 17-1400 [58]

West Midlands, UK

pubs and

restaurant 4 100 220 230 52-350 [39]

Michigan, US

several ^a 12 100 223 134 20-938 [65]

a equipment sales/service room (2 samples), university building (2 samples), computer server room and office (3 samples), medical equipment manufacturer (2 samples), art museum (2 samples), tire store (1 sample).

b NA: not available.

ND= not detected; MQL = method quantification limit