Science of the Total Environment

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Occurrence of phthalate diesters in indoor air from several Northern cities in Vietnam, and its implication for human exposure

Tri Manh Tran

^a,

⁎ , Hanh Thi Le

^a

, Tu Binh Minh

^a

, Kurunthachalam Kannan

^b,c,d,

⁎⁎

aFaculty of Chemistry, VNU University of Science, Vietnam National University, Hanoi, 19 Le Thanh Tong, Hoankiem, Hanoi, Vietnam

bWadsworth Center, New York State Department of Health, Empire State Plaza, P.O. Box 509, Albany, NY 12201-0509, United States

cBiochemistry Department, Faculty of Science and Experimental Biochemistry Unit, King Fahd Medical Research Center, King Abdulaziz University, Jeddah 21589, Saudi Arabia

dDepartment of Environmental Health Sciences, School of Public Health, State University of New York at Albany, Empire State Plaza, P.O. Box 509, Albany, NY 12201-0509, United States

H I G H L I G H T S

•Ten phthalate diesters were determined in 97 indoor air samples.

•Concentrations of phthalates ranged from 106 to 16,000 ng/m³ with the highest levels in hair salons.

•Diethyl phthalate accounted forN38% of phthalate concentrations in indoor air.

•Inhalation exposure to phthalates is higher than that from dust ingestion.

G R A P H I C A L A B S T R A C T

a b s t r a c t a r t i c l e i n f o

Article history:

Received 24 April 2017

Received in revised form 29 May 2017 Accepted 2 June 2017

Available online xxxx Editor: Jay Gan

Phthalates are used as plasticizers to impartﬂexibility of plastics. Because of their toxicity, human exposure to phthalates is a concern. Little is known on the occurrence of and inhalation exposure to phthalates in indoor air. In this study, ten phthalates were measured in 97 indoor air samples collected from Northern Vietnam during September 2016 to January 2017. The mean concentrations of total phthalates (i.e., sum of ten phthalates) in particulate and gas phases ranged from 95.2 to 13,100μg g⁻¹and from 57.0 to 14,900 ng m⁻³, respectively. In bulk indoor air samples (i.e., gas plus particulate phase), the mean concentration of total phthalates ranged from 106 to 16,000 ng m⁻³(mean: 1040 ng m⁻³). Diethyl phthalate (DEP) was found at the highest concentration in indoor air at a concentration range of below the method quantitation limit (MQL) to 12,400 ng m⁻³(mean: 376).

Among various microenvironments, indoor air collected from hair salons contained the highest concentrations of phthalates (range: 596 to 16,000 ng m⁻³). Among the four northern Vietnamese cities studied, the highest concentrations of phthalates were found in indoor air samples from Hanoi. The calculated mean inhalation exposure doses to phthalates for infants, toddlers, children, teenagers, and adults were 780, 485, 416, 292, and 213 ng kg- bw⁻¹d⁻¹, respectively.

Keywords:

Phthalates DEP DEHP Indoor air Inhalation exposure

⁎ Corresponding author.

⁎⁎ Correspondence to: K. Kannan, Department of Environmental Health Sciences, School of Public Health, State University of New York at Albany, Empire State Plaza, P.O. Box 509, Albany, NY 12201-0509, United States.

E-mail addresses:[email protected](T.M. Tran),[email protected](K. Kannan).

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1. Introduction

Phthalates are used in various consumer, household, and industrial products as plasticizers. Phthalates can be found in building materials, clothing, personal care products (PCPs), food packaging, toys, vinyl products, lubricating oils, solvents, and detergents (U.S. EPA, 2008;

Clausen et al., 2012). Di(2-ethylhexyl) phthalate (DEHP) was the major phthalate ester found in foods, with a median concentration of 28 ng g⁻¹in dairy products, 86 ng g⁻¹inﬁsh, and 44.5 ng g⁻¹in meats from the United States (Schecter et al., 2013). Diethyl phthalate (DEP) and dibutyl phthalate (DBP) were found in cosmetics and personal care products at concentration as high as 25,500μg g⁻¹ and 24,300μg g⁻¹, respectively (Buck-Louis et al., 2013; Guo and Kannan, 2013; Guo et al., 2014). These studies suggest the existence of a wide va- riety of sources of human exposure to phthalates.

A few studies have reported the occurrence of phthalates in indoor environments, especially in indoor dust (Guo and Kannan, 2011;

Kubwabo et al., 2013; Ma et al., 2014). The total concentrations of seven phthalates in house and dormitory dust samples from China were 672 and 533μg g⁻¹, respectively (Li et al., 2016). Recently, we reported the occurrence of phthalates in indoor dust collected from several Northern cities in Vietnam at a concentration range of 3.4 to 160μg g⁻¹(median: 22.6μg g⁻¹) (Tran et al., 2016). Although studies have reported the occurrence of phthalates in house dust, very few have measured these compounds in airborne particulate and vapor phases of indoor air. Analysis of phthalates in indoor air can provide information related to inhalation exposure to these endocrine disrupting chemicals. Indoor air concentrations of nine phthalates have been reported from the USA, and that study showed the highest levels in air from hair salons (Tran and Kannan, 2015).Fromme et al. (2004)reported the occurrence of DBP in indoor air at median concentrations of 1080 ng m⁻³in apartments and 1190 ng m⁻³in kindergartens in Ber- lin, Germany. The mean concentrations of six individual phthalates in indoor air of homes, daycare centers, and ofﬁces in Stockholm, Sweden, ranged from 4.6 to 1600 ng m⁻³(Bergh et al., 2011). The median concentrations of seven phthalates in indoor air from France were from b0.6 to 326 ng m⁻³(Blanchard et al., 2014).

Studies have reported human exposure doses to phthalates through the ingestion of dust and diet in various countries (Guo and Kannan, 2011, 2012, 2013; Guo et al., 2011a, 2011b; Schecter et al., 2013). The sources of human exposure to phthalates vary depending on the type of phthalates. For instance, diet was the major source of exposure to DEHP, whereas dermal and inhalation pathways were the major sources of exposure to DEP and DBP (Guo et al., 2014; Shi and Zhao, 2014). A previous study reported median total indoor exposure to DiBP, DEHP, and DEP at 1890, 830, and 620 ng kg-bw⁻¹d⁻¹, respectively (Bekö et al., 2015).

Studies have shown that phthalates elicit reproductive and develop- mental toxicities in laboratory animals (Gray et al., 2006; Boberg et al., 2008). Speciﬁcally, phthalate exposure was shown to be associated with endocrine disruption, respiratory effects, and reproductive toxicities (Lin et al., 2011; Buck-Louis et al., 2013). A comprehensive assessment of sources of exposure to phthalates is needed to develop strategies for reducing exposures. In the present survey, ten phthalate diesters were determined in 97 indoor air samples collected from four Northern cities in Vietnam. Partitioning of phthalate esters between particulate and gas phases of indoor air was determined. Further, human exposure dose to phthalates through inhalation of indoor air was estimated.

2. Materials and methods 2.1. Standards and chemicals

Ten phthalate diesters, dimethyl phthalate (DMP), diethyl phthalate (DEP), dipropyl phthalate (DPP), diisobutyl phthalate (DiBP), dibutyl

phthalate (DBP), di-n-hexyl phthalate (DnHP), benzyl butyl phthalate (BzBP), dicyclohexyl phthalate (DCHP), di(2-ethylhexyl) phthalate (DEHP), and di-n-octyl phthalate (DnOP) were analyzed. Sevend₄(deuterated) standards,d4-DMP,d4-DEP,d4-DPP,d4-DiBP,d4-DnHP,d4-BzBP, andd4-DEHP were used as internal standards.

2.2. Sample collection

Polyurethane foam (PUF) plugs (ORBO-1000, PUF dimension: 2.2 cm O.D. × 7.6 cm length) were purchased from Supelco (Bellefonte, PA, USA). The background levels of phthalates present in PUFs have been reported in our earlier study (Tran and Kannan, 2015). All PUF plugs re- quired purification prior to use, as described in our earlier study (Tran and Kannan, 2015). Quartzfiberfilters (Whatman, grade MQ-A, pore size: 2.2μm with a particle retention rating at 98% efficiency, 32 mm di- ameter) were prepared by heating at 400 °C for 24 h, and then kept in a desiccator at room temperature until further use. The quartzfiberfilters were weighed in an analytical balance (to nearest 0.01 mg) before and after collection of air samples for the determination of particle content in air.

Two PUF plugs were packed in tandem in a glass tube (ACE glass, Vineland, NJ, USA; 2,2 cm O.D. × 25 cm length), and the quartzfiberfilter was held on top of the glass tube packed with PUF plugs with a Tef- lon cartridge (Supelco, PUFfilter cartridge assembly). All glassware used for sampling and analysis was rinsed with acetone andn-hexane and heated at 400 °C immediately prior to use.

Indoor air samples were collected for 12 to 24 h by a low-volume air sampler (LP-7 230 V pump kit, A.P. Buck Inc., Orlando, FL, USA) at aflow rate of 4 L per minute. The total volume of air collected from each location ranged from 2.88 to 5.76 m³. Air samples (both PUFs and glassfiber filters) were kept at−18 °C until analysis. The samples were kept for no longer than 2 weeks for extraction and analysis. Ninety-seven samples were collected from September 2016 to January 2017 in four Northern cities in Vietnam (Table S1, Supporting Information). The sampling locations in Hanoi city were grouped into six categories: homes (n = 19), cars (n = 8), kindergartens (n = 7), laboratories (n = 19), offices (n = 9), and hair salons (n = 13). For other cities, air samples were only collected at homes: Bacninh (n = 8), Thaibinh (n = 6), and Tuyenquang (n = 8).

2.3. Analytical procedure

Prior to analysis, samples (both PUFs andfilters) were spiked with 500 ng each ofd4-labeled surrogate standards. The extraction procedure was similar to that described earlier (Tran and Kannan, 2015) with slight modifications. Two PUF plugs were extracted by shaking in an or- bital shaker (Stuart, Japan) with dichloromethane (DCM) andn-hexane (3:2, v:v) for 30 min. The extraction was performed twice, with 100 mL solvent mixture for thefirst extraction and 80 mL for the second. The ex- tracts were concentrated in a rotary evaporator (IKA RV 05, Staufen, Germany) at 40 °C to approximately 5 mL. The solution was then transferred into a 12-mL glass tube and concentrated by a gentle stream of nitrogen to exactly 1 mL and transferred into a GC vial. The particulate fraction was extracted by shaking the quartzfiberfilters with a 5 mL mixture of DCM andn-hexane (3:2, v:v) each time for 5 min, which was performed three times. The extract was concentrated under a gentle stream of nitrogen to exactly 1 mL and transferred into a GC vial.

An Agilent Technologies 7890B gas chromatograph (GC) interfaced with a 5977A mass spectrometer (MS) was used for the analysis of phthalates. Chromatographic separation of phthalates was achieved by a DB-5MS capillary column. Further details of the analysis are provided in the Supporting Information and elsewhere (Guo and Kannan, 2012, 2013; Guo et al., 2014; Tran and Kannan, 2015).

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2.4. Quality assurance and quality control

A major challenge in the analysis of low levels of phthalates is background contamination in laboratory materials. Methods to eliminate contamination in laboratory materials, including solvents used in extraction, have been studied in our laboratory (Guo and Kannan, 2012, 2013; Guo et al., 2012, 2014; Tran and Kannan, 2015; Tran et al., 2016). Procedural blanks were analyzed with every batch of samples.

Trace levels of DEP (2.3–15.7 ng), DiBP (2.6–14.5 ng), DBP (4.2– 18.9 ng), BzBP (2.5–6.2 ng), and DEHP (5.5–30.2 ng) were found in procedural blanks (n = 16) involving new PUFs, and DiBP (1.5–5.9 ng), DBP (2.0–8.8 ng), and DEHP (3.3–12.8 ng) were found in procedural blanks (n = 8) for quartzﬁberﬁlters. All reported concentrations in indoor air samples were subtracted from the mean value found in procedural blanks. The calibration curve was linear over a concentration range of 0.4 to 1000 ng mL⁻¹for individual phthalates (R²N0.995).

An amount of 500 ng each of native and surrogate standards (d4- phthalates) was spiked into a blank PUF and quartzfiberfilter and passed through the entire analytical procedure. The recoveries of target compounds spiked into PUFs andfilters are shown inTable 1. The concentrations of phthalates in samples (both PUFs andfilters) were calculated based on the responses of corresponding deuterated surrogate standards (except for BBP, DCHP, and DnOP, which were calculated based on the responses ofd4-DiBP,d4-DnHP, andd4-DEHP, respectively). The method detection limit (MDL) and the method quantification limit (MQL) were determined from an average volume of air collected (4.46 m³), average weight of airborne particles collected (0.35 mg), and the lowest point in the calibration standard with a signal-to-noise ratio of 3 and 10, respectively. The MQLs ranged from 0.1 to 0.3 ng m⁻³for the gas phase and from 1.5 to 4.5μg g⁻¹for the particulate phase (Table 1). For values below the MQL, the concentrations were assigned a value at one-half of the MQL for statistical analysis, which was performed by Microsoft Excel (Microsoft Office 2010) and GraphPad Prism version 7.0. The equations used in the calculation of partitioning coefficients are provided in the Supporting Information.

3. Results and discussion

3.1. Concentration of phthalates in particulate phase

The concentrations of individual phthalates in particulate fraction of indoor air (Table S2, Supporting Information) were calculated based on

the weight of the airborne particles collected on the quartzﬁberﬁlter (that ranged from 0.12 to 0.61 mg). DBP was found in all samples.

DEP, DiBP, and DEHP were found in 98% of the samples, whereas DMP was found in 48.5% of the samples. DEHP was found at the highest concentration that ranged between below MQL and 7950μg g⁻¹(mean:

1790 and median: 1240). The distribution proﬁles of phthalates in particulate phase are shown inFig. 1a.

The sum concentrations of ten phthalates in particulate phase ranged from 95.2 to 13,100μg g⁻¹(mean: 3570, i.e., approximately 0.36% by weight). The highest concentrations of phthalates were found in particulate fraction of indoor air from hair salons. The concentrations of phthalates in airborne particles were hundred times higher than the concentrations reported in indoor dust from Vietnam (Tran et al., 2016). These results suggest that phthalates tend to be bound to aerosols. Personal care products (PCPs) are the major sources for phthalates in the indoor environment (Guo and Kannan, 2013; Guo et al., 2014; Ma et al., 2014), and elevated concentrations found in hair salons can be explained by the high use of PCPs in that setting.

3.2. Concentration of phthalates in vapor phase

The measured concentrations of phthalates in gas (vapor) phase of indoor air are shown in Table S4 (Supporting Information). The sum concentrations of phthalates in gas phase ranged from 57.0 to 14,900 ng m⁻³. Similar to that found for the particulate fraction, phthalate concentrations were elevated in the gaseous fraction of air from hair salons. The distribution proﬁles of phthalates in gas phase of indoor air samples collected from various locations are presented inFig. 1b. DEP was found at the highest levels in the vapor phase (range:bMQL to 12,400; mean: 367 and median: 27.3 ng m⁻³), while DEHP predominat- ed the particulate fraction. These results suggest a difference in the distribution of DEP and DEHP between vapor and particulate phases (Fig.

2). The mean concentration of DEP was 37 times higher in gas phase than in particulate phase. Nevertheless, the ratio of DEP concentrations between the gas and particulate phases was lower in this study than that reported from France (Blanchard et al., 2014) (157 times), but 6 times higher than that reported from the USA (Tran and Kannan, 2015). Similarly, the mean concentration of DiBP measured in the vapor phase (172 ng m⁻³) was 3.5 times greater than that measured in the particulate phase (52.2 ng m⁻³). The mean concentrations of individual phthalates in the gas phase ranged from 0.58 ng m⁻³(DnHP)

Table 1

The method detection limit (MDL), quantiﬁcation limit (MQL) and recoveries (%) of phthalates and d4-phthalates through the analytical method used in this study.

Target compounds Particulate phase Gas phase

Recoveries (%) Recoveries (%)

MDL (μg g⁻¹) MQL (μg g⁻¹) Range Mean STDEV MDL (ng m⁻³) MQL (ng m⁻³) Range Mean STDEV

DMP 1.0 3.0 63.6–132 87.2 13.4 0.07 0.2 71.0–129 93.1 17.6

DEP 0.5 1.5 70.9–125 98.7 12.8 0.03 0.1 64.6–118 85.5 14.5

DPP 0.5 1.5 72.2–107 94.4 16.5 0.03 0.1 67.9–122 89.5 13.5

DiBP 0.5 1.5 71.5–129 89.9 14.7 0.03 0.1 69.8–125 104 14.0

DBP 0.5 1.5 80.8–122 101 9.2 0.03 0.1 70.3–121 89.6 13.5

DnHP 1.0 3.0 77.0–118 90.5 12.4 0.07 0.2 74.4–109 92.2 11.8

BzBP 1.0 3.0 63.7–111 95.6 13.5 0.05 0.15 75.9–116 94.5 13.9

DCHP 1.5 4.5 75.5–117 102 14.3 0.1 0.3 72.1–120 97.7 14.5

DEHP 0.5 1.5 64.5–128 103 16.1 0.03 0.1 67.9–130 105 17.2

DnOP 1.5 4.5 61.9–121 95.6 13.8 0.1 0.3 66.6–124 84.5 14.5

Surrogate standards

d4-DMP – – 66.2–111 88.2 12.6 – – 69.0–120 89.8 15.6

d4-DEP – – 66.4–115 90.1 13.8 – – 67.8–119 94.4 14.8

d4-DPP – – 68.2–120 95.3 15.8 – – 66.4–123 96.6 14.0

d4-DiHP – – 70.5–117 90.3 13.4 – – 65.6–119 92.7 13.4

d4-DnHP – – 68.9–118 92.3 13.1 – – 67.5–116 93.4 14.3

d4-BzBP – – 68.8–120 93.2 15.3 – – 64.7–121 91.2 15.5

d4-DEHP – – 74.1–119 98.2 13.2 – – 70.4–120 93.9 14.0

Method detection limit (MDL) and method quantiﬁcation limit (MQL) were calculated on the basis of average volume of air collected which was 4.46 m³and the average weight of air borne particles collected, which was 0.35 mg. STDEV: standard deviation.

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to 367 ng m⁻³(DEP), and those in the particulate phase ranged from 0.75 ng m⁻³(DnHP) to 129 ng m⁻³(DEHP) (Fig. 2).

3.3. Gas-particle and octanol-air partition coefﬁcients of phthalates

The gas-particle partition coefﬁcient (KP) and the octanol-air partition coefﬁcient (KOA) of phthalate diesters were estimated based on the concentrations measured in the gas and particulate phases of indoor air (Tran and Kannan, 2015). The theories and equations for calculating log(KP) and log(KOA) of phthalates have been described in previous studies (Finizio et al., 1997; Fromme et al., 2005; Weschler and Nazaroff, 2010; Schossler et al., 2011; Tran and Kannan, 2015) and are further described in the Supporting Information.

We determined K_Pand log(K_P) based on the ratio of the mean concentrations of individual phthalates between particulate and gas phases (Tables S2 and S3, Supporting Information). The equation: log(KOA)= log(KP) + 12.40 was used in the calculation of log(KOA) (Table 2). The measured log(KP) and the log(KOA) values of low molecular weight phthalates were lower than those of high molecular weight phthalates.

The log(KOA) value ranged from 8.92 for DEP (lowest) to 10.9 for DEHP (highest) (Table 2). Overall, our results indicate that the low molecular weight phthalates, such as DEP and DMP, partition preferentially toward the vapor phase, whereas the high molecular weight phthalates, such as DEHP, tend to partition more toward the particulate phase in air. The results of this model are supported by the data presented above (Fig. 2).

3.4. Phthalates in bulk (particulate plus gas phase) indoor air

The total concentrations of phthalates in bulk of indoor air were determined by the summation of concentrations measured in particulate and gas phases on a volumetric (m³) basis (Table 3). The mean concentration of phthalates was the highest in indoor air collected from hair salons (3590 ng m⁻³) and the lowest in homes from Tuyenquang (mean:

231 ng m⁻³). DBP was found in all samples, which was followed by DiBP (99%), DEP and DEHP (97.9%). DEP was found at the highest concentration in bulk air samples (mean: 376 ng m⁻³), followed by DiBP (mean: 224 ng m⁻³) and DEHP (mean: 187 ng m⁻³).

The highest mean concentration of phthalates was found in hair salons (3590 ng m⁻³), which was followed by indoor air samples from kindergartens (867 ng m⁻³) and homes (846 ng m⁻³) in Hanoi. The mean total concentration of phthalates in hair salons was 5 times higher than the lowest value of 715 ng m⁻³found in laboratories in Hanoi. The total mean concentration of phthalates found in indoor air from Viet- nam was similar to that reported from Albany, New York, USA (Tran and Kannan, 2015) and Sapporo, Japan (Kanazawa et al., 2010). Howev- er, the concentrations of phthalates in indoor air from Vietnam were ten times lower than those reported from Hangzhou, China (Pei et al., 2013) (Table 4). These results suggest country-speciﬁc differences in the pro- ﬁles of phthalates in indoor air, which may be due to the differences in the use of personal care products/cosmetics, life style and indoor environment (e.g., ventilation, temperature, furniture) in each country.

Among the four cities surveyed, the total concentrations of phthalates were the highest in indoor air in homes of Hanoi (mean:

846 ng m⁻³and median: 756 ng m⁻³) (Fig. 3). The mean concentrations of phthalates in homes in Bacninh, Thaibinh, and Tuyenquang were approximately 4-fold lower than those in Hanoi. These results were similar to those reported for indoor dust from homes in various Fig. 1.Distribution proﬁles of phthalates in particulate phase (1a) and gas phase (1b) of indoor air samples collected from various locations in Northern Vietnam. HN, BN, TB, and TQ refer respectively to Hanoi, Bacninh, Thaibinh, and Tuyenquang. Values inparenthesesrefer to the number of samples analyzed.

Fig. 2.Concentrations of individual phthalates in gas and particulate phases of indoor air (n = 97) from four Northern cities in Vietnam.

Table 2

Estimated log(Kp) and log(Kow) values for phthalate diesters (on the basis of the concentration measured in particulate and gas phases of indoor air from four Northern cities in Vietnam, n = 97).

Phthalates log(Kp) log(Kow)

Range Mean Range Mean

DMP −3.67 to−2.98 −3.34 8.73 to 9.42 9.06 DEP −3.65 to−2.61 −3.48 8.74 to 9.78 8.92 DPP −3.01 to−1.61 −2.37 9.39 to 10.8 10.0 DiBP −3.13 to−1.91 −2.40 9.27 to 10.5 10.0 DBP −2.50 to−1.72 −2.23 9.90 to 10.7 10.2 DnHP −1.97 to−1.51 −1.72 10.4 to 10.9 10.7 BzBP −3.11 to−1.81 −2.77 9.28 to 10.6 9.63 DCHP −1.91 to−1.00 −1.81 10.5 to 11.4 10.6 DEHP −2.07 to−0.98 −1.51 10.3 to 11.4 10.9 DnOP −2.17 to−1.32 −1.62 10.2 to 11.1 10.8

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cities in Vietnam (Tran et al., 2016). Hanoi is the most populous urban center in Vietnam (7.2 million), followed by Thaibinh (1.8 million), Bacninh (1.2 million), and Tuyenquang (0.76 million) (Vietnam Government, General Statistics Ofﬁce, 2015). Our results suggest that homes in urban areas contain elevated concentrations of phthalates.

The correlations of concentrations of several phthalate pairs in individual indoor air samples were considered (Fig. S1, Supporting Informa- tion). A signiﬁcant correlation existed between DiBP and DBP as well as DiBP and DEHP in indoor air (Pb0.0001).

3.5. Human exposure to phthalates via inhalation

On the basis of the average inhalation rate of 4.5 m³d⁻¹for infants, 7.0 m³d⁻¹for toddlers, 10.0 m³d⁻¹for children, and 13.5 m³d⁻¹for

teenagers and adults (U.S. EPA, 2008), we calculated the inhalation exposure to phthalates by multiplying the measured concentrations in indoor air (ng m⁻³) with the volume of air inhaled (m³). The average body weights (bw) for Vietnamese was applied as: infants (6– 12 months): 8 kg, toddlers (1–5 yrs): 15 kg, children (6–11 yrs):

25 kg, teenagers (12–18 yrs): 48 kg, and adults (≥19 yrs): 66 kg (Vietnam encyclopedic knowledge, 2014).

The calculated inhalation exposure doses of total phthalates for infants, toddlers, children, teenagers, and adults were 780, 485, 416, 292, and 213 ng kg-bw⁻¹d⁻¹, respectively (Table 5). Overall, these results suggest that exposure doses to phthalates through inhalation de- crease with age. These values were 8–15 times higher than that estimated for dust ingestion (Tran et al., 2016), which suggests that inhalation is an important pathway of exposure to phthalates.

Table 3

Total concentrations of individual phthalates in bulk indoor air (ng m⁻³) (sum of particulate and gas phases) from Northern Vietnam.

Categories DMP DEP DPP DiBP DBP DnHP BzBP DCHP DEHP DnOP ∑Phthalates

Homes HN (n = 19) Range n.d.–58.2 n.d.–1910 0.58–267 11.6–478 1.34–517 n.d.–4.22 n.d.–149 n.d.–169 5.88–405 n.d.–61.6 210–2400

Mean 16.1 267 44.3 201 127 1.61 36.8 31.7 112 8.43 846

Median 10.6 57.6 3.96 137 67.0 1.33 3.57 8.23 56.0 5.46 756

DR% 89.5 94.7 100 100 100 68.4 94.7 89.5 100 79.0

Cars HN (n = 8) Range 4.12–367 7.0–506 2.9–36.0 9.36–208 2.22–145 n.d.–2.93 3.59–121 3.94–45.4 81.4–670 n.d.–29.0 277–1080

Mean 85.1 136 12.4 83.0 57.1 2.06 31.0 19.0 313 12.0 751

Median 28.6 43.6 8.08 78.6 46.7 2.28 5.20 9.72 241 11.4 781

DR% 100 100 100 100 100 87.5 100 100 100 87.5

Kindergartens HN (n = 7) Range n.d.–40.8 1.91–208 0.75–69.5 11.0–1170 2.91–509 n.d.–2.40 n.d.–25.5 n.d.–10.3 39.1–529 1.22–17.8 135–1600

Mean 16.1 72.8 15.8 334 145 1.02 7.55 4.54 261 9.35 867

Median 13.9 58.9 2.91 166 99.5 0.89 3.41 4.52 244 9.31 1000

DR% 85.7 100 100 100 100 57.1 85.7 85.7 100 100

Laboratories HN (n = 19) Range n.d.–86.1 n.d.–398 0.71–70.0 24.1–350 1.54–487 n.d.–3.88 n.d.–107 n.d.–371 n.d.–529 n.d.–60.5 112–1470

Mean 30.4 42.9 10.4 164 143 1.22 12.2 82.7 213 15.7 716

Median 18.3 11.1 38.8 138 2.64 1.83 4.29 76.6 46.1 86.4 582

DR% 89.5 94.7 100 100 100 79.0 94.7 94.7 94.7 73.7

Ofﬁces HN (n = 9) Range n.d.–163 2.41–1010 0.91–55.2 19.5–346 2.86–279 n.d.–4.65 n.d.–51.6 1.27–138 26.9–501 n.d.–56.6 152–1460

Mean 32.5 242 15.5 121 75.0 1.80 13.1 22.6 210 11.2 745

Median 13.8 176 5.37 98.3 67.1 1.39 2.83 4.14 219 5.55 759

DR% 88.9 100 100 100 100 88.9 88.9 100 100 77.8

Hair salons HN (n = 13) Range 4.97–771 62.5–12,400 n.d.–200 28.6–2580 2.60–1360 n.d.–3.04 n.d.–68.7 n.d.–398 38.1–598 n.d.–101 569–16,000

Mean 125 2030 18.2 731 348 1.19 11.0 35.2 272 17.7 3590

Median 34.7 488 2.62 666 162 1.21 2.32 3.05 257 11.3 1760

DR% 100 100 92.3 100 100 53.9 92.3 92.3 100 84.6

Homes BN (n = 8) Range n.d.–5.79 9.48–43.4 n.d.–4.30 37.5–75.7 23.6–81.7 n.d.–1.53 n.d.–3.42 n.d.–9.05 55.6–262 n.d.–8.82 164–426

Mean 2.95 19.6 3.01 55.9 53.7 0.63 2.22 3.40 147 4.75 293

Median 3.11 16.5 3.45 55.0 54.2 0.60 2.28 3.11 137 4.82 294

DR% 75.0 100 87.5 100 100 37.5 87.5 75.0 100 75.0

Homes TB (n = 6) Range 0.86–66.4 4.02–58.5 0.73–34.8 13.1–141 4.47–215 n.d.–3.62 n.d.–21.8 1.64–41.2 4.54–140 n.d.–9.56 106–456

Mean 18.7 28.8 15.0 63.0 45.7 1.89 10.2 13.1 51.6 3.96 252

Median 3.95 26.2 17.0 55.3 6.11 1.46 6.15 9.36 25.3 2.17 214

DR% 100 100 100 100 100 83.3 83.3 100 100 83.3

Homes TQ (n = 8) Range n.d.–32.2 5.18–34.3 n.d.–4.18 28.9–76.0 22.9–64.3 n.d.–0.75 n.d.–3.16 n.d.–3.51 11.8–180 n.d.–11.1 181–311

Mean 13.6 15.9 2.38 46.3 45.9 0.55 2.25 2.53 95.8 5.94 231

Median 13.7 14.5 2.60 39.4 52.4 0.64 2.32 2.50 95.5 5.71 223

DR% 87.5 100 87.5 100 100 50.0 87.5 87.5 100 75.0

Total (n = 97) Range n.d.–771 n.d.–12,400 n.d.–267 n.d.–2580 1.34–1360 n.d.–4.65 n.d.–149 n.d.–398 n.d.–670 n.d.–101 106–16,000

Mean 39.5 376 18.1 224 133 1.34 16.4 32.4 187 10.9 1040

Median 12.0 34.3 2.97 114 66.1 0.97 3.02 4.54 144 6.51 596

DR% 90.7 97.9 93.8 90.0 100 67.0 90.7 86.6 97.9 76.3

HN, BN, TB, and TQ refer respectively to Hanoi, Bacninh, Thaibinh, and Tuyenquang. Values in parentheses (next to categories) refer to the number of samples analyzed. DR%: percent detection rates. n.d.: not detectable.

Table 4

Comparison of concentration of phthalates in indoor air from different countries (ng m⁻³).

Reference n Range Mean Median Phthalates Country Cities

Present study 97 106–16,000 1040 596 DMP, DEP, DPP, DiBP, DBP, DnHP, BzBP, DCHP, DEHP, DnOP Vietnam Hanoi, Bacninh, Thaibinh, Tuyenquang Tran and Kannan, 2015 60 53.6–4850 778 390 DMP, DEP, DiBP, DBP, DnHP, BzBP, DCHP, DEHP, DnOP USA Albany

Pei et al., 2013 30 9740–17,400 12,100 n.a. DMP, DEP, DBP, BzBP, DEHP China Hangzhou

Bergh et al., 2011 31 740–7400 2430 2030 DMP, DEP, DiBP, DBP, BzBP, DEHP Sweden Stockholm

Kanazawa et al., 2010 41 139–3330 n.a. 531 DMP, DEP, DiBP, DBP, BzBP, DEHP, DnNP Japan Sapporo

Rudel et al., 2003 120 193–7200 n.a. 948 DMP, DEP, DPP, DiBP, BzBP, DCHP, DEHP USA Massachusetts

n refer the number of samples; n.a.: not available.

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Furthermore, the inhalation exposure doses calculated for Vietnamese were two times higher than those reported for Americans (Tran and Kannan, 2015).

Based on the mean measured concentrations, the human exposure doses to individual phthalate through inhalation were also estimated for various age groups (Table S5, Supporting Information). The exposure doses to DEP were the highest and ranged from 77.0 ng kg-bw⁻¹d⁻¹ for adults to 282 ng kg-bw⁻¹d⁻¹for infants, followed by DiBP (45.8– 168 ng kg-bw⁻¹d⁻¹), and DEHP (38.3–141 ng kg-bw⁻¹d⁻¹). These results were similar those found in a previous study, that showed an average inhalation exposure dose to DEHP (gas plus particulate phase) in China at 119 ng kg-bw⁻¹d⁻¹(Shi and Zhao, 2014). The inhalation exposure to phthalates varies depending on the duration people stay in various micro-environments. The highest exposure doses to phthalates were through inhalation at hair salons, followed by kindergartens and homes. However, people spend most of the times at homes and there- fore the exposure doses calculated here may overestimate actual values.

4. Conclusions

This is theﬁrst study to report the occurrence of phthalates in indoor air from Vietnam. The measured concentrations of phthalates in indoor air from Vietnam were comparable to those reported in the USA and other western countries. Indoor air samples from hair salons contained the highest concentrations of phthalates. Furthermore, indoor air samples from homes in metropolitan cities such as Hanoi contained higher concentration of phthalates than those in suburban areas.

Acknowledgment

This study was funded by Vietnam National Foundation for Science and Technology Development (NAFOSTED) under the grant number 104.01-2015.24.

Appendix A. Supplementary data

Supplementary data to this article can be found online athttp://dx.

doi.org/10.1016/j.scitotenv.2017.06.016.

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Fig. 3.Total mean and range of concentrations of phthalates in indoor air from different sampling locations in Northern Vietnam. HN, BN, TB, and TQ refer respectively to Hanoi, Bacninh, Thaibinh, and Tuyenquang. Values inparenthesesrefer to the number of samples analyzed.

Table 5

Human exposure doses to total phthalates through indoor air inhalation in four Northern cities in Vietnam (ng kg-bw⁻¹d⁻¹).^a

Categories Infants Toddlers Children Teenagers Adults

Homes HN 634 395 338 238 173

Cars HN 563 350 300 211 154

Kindergartens HN 651 405 347 244 177

Laboratories HN 537 334 286 201 146

Ofﬁces HN 559 348 298 210 152

Hair salons HN 2690 1680 1440 1010 734

Homes BN 220 137 117 82.5 60.0

Homes TB 189 118 101 70.9 51.5

Homes TQ 173 108 92.5 65.0 47.3

Total 780 485 416 292 213

HN, BN, TB, and TQ refer respectively to Hanoi, Bacninh, Thaibinh, and Tuyenquang. Infants (6–12 months) = 6 kg-bw; toddlers (1–5 yrs) = 15 kg-bw; children (6–10 yrs) = 25 kg- bw; teenagers (11–17 yrs) = 48 kg-bw; adults (N18 yrs) 66 kg-bw (Vietnam encyclopedic knowledge, 2014).

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