Chemosphere 133 (2015) 47–52

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Occurrence of organophosphorus flame retardants in indoor dust in multiple microenvironments of southern China and implications for human exposure Chun-Tao He a, Jing Zheng b, Lin Qiao a, She-Jun Chen c,⇑, Jun-Zhi Yang a, Jian-Gang Yuan a, Zhong-Yi Yang a,⇑, Bi-Xian Mai c a

State Key Laboratory for Biocontrol, School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, China Center for Environmental Health Research, South China Institute of Environmental Sciences, Ministry of Environmental Protection, Guangzhou 510655, China c State Key Laboratory of Organic Geochemistry and Guangdong Key Laboratory of Environmental Resources Utilization and Protection, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China b

h i g h l i g h t s  OPFRs were measured in indoor dust from four microenvironments in southern China.  The OPFR concentrations in indoor dust from the e-waste area were highest.  The OPFR compositions reflected three types of OPFR sources to the indoor dust.  Concerns should be paid to the exposure of toddlers in the e-waste area to OPFRs.

a r t i c l e

i n f o

Article history: Received 6 January 2015 Received in revised form 18 March 2015 Accepted 20 March 2015 Available online 18 April 2015 Handling Editor: J. de Boer Keywords: Organophosphorus flame retardants (OPFRs) Indoor dust E-waste Urban Human exposure

a b s t r a c t Organophosphorus flame retardants (OPFRs) are important alternatives to brominated flame retardants (BFRs), but information on their contamination of the environment in China is rare. We examined the occurrence of 12 OPFRs in indoor dust in four microenvironments of southern China, including a rural electronic waste (e-waste) recycling area, a rural non-e-waste area, urban homes, and urban college dormitory rooms. The OPFR concentrations (with a median of 25.0 lg g 1) were highest in the e-waste area, and the concentrations in other three areas were lower and comparable (7.48–11.0 lg g 1). The levels of OPFRs in the present study were generally relatively lower than the levels of OPFRs found in Europe, Canada, and Japan because BFRs are still widely used as the major FRs in China. The composition profile of OPFRs in the e-waste area was dominated by tricresyl phosphate (TCP) (accounting for 40.7%, on average), while tris(2-chloroethyl) phosphate (TCEP) was the most abundant OPFR (64.4%) in the urban areas (homes and college dormitories). These two distribution patterns represent two OPFR sources (i.e., emissions from past e-waste and from current household products and building materials). The difference in the OPFR profiles in the rural area relative to the OPFR profiles in the urban and e-waste areas suggests that the occurrence of OPFRs is due mainly to emissions from characteristic household products in rural homes. Although human exposures to all the OPFRs were under the reference doses, the health risk for residents in the e-waste area is a concern, considering the poor sanitary conditions in this area and exposure from other sources. Ó 2015 Elsevier Ltd. All rights reserved.

1. Introduction Flame retardants are an important class of additives for a wide range of commercial products to meet rigorous flammability ⇑ Corresponding author. Tel.: +86 20 85291509; fax: +86 2085290706. E-mail addresses: [email protected] (S.-J. Chen), [email protected] (Z.-Y. Yang). http://dx.doi.org/10.1016/j.chemosphere.2015.03.043 0045-6535/Ó 2015 Elsevier Ltd. All rights reserved.

standards. With the phase-out or restriction of brominated flame retardants (BFRs), the consumption of BFRs is declining, while the market demand for alternative flame retardants is growing (Van der Veen and de Boer, 2012). Organophosphorus flame retardants (OPFRs), often used in furniture, building material, and electronic equipment (Stapleton et al., 2014; Takigami et al., 2009), are proposed as alternatives for polybrominated diphenyl ethers (PBDEs). For example, tris(2-chloroethyl) phosphate (TCEP),

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tris(1-chloro-2-propyl) phosphate (TCPP) and tris(1,3-dichloroisopropyl)phosphate (TDCP) are used as replacements for penta-BDE (Dodson et al., 2012), and triphenyl phosphate (TPhP) is a potential deca-BDE alternative (USEPA, 2007). Some OPFRs are also used as plasticizers and additives in hydraulic fluids (Ali et al., 2012). The global market for OPFRs was estimated to be 150 000 metric tons in 2010 (Ou, 2011). The physicochemical properties such as octanol-water partition coefficient (KOW), water solubility, and vapor pressure of OPFRs differ greatly (Reemtsma et al., 2008; Van der Veen and de Boer, 2012), and these chemicals are usually mixed into (not chemically bonded to) the polymer. Consequently, the OPFRs may be released into the environment through volatilization, abrasion, or leaching during production, use, and disposal of treated products (Marklund et al., 2005; Van den Eede et al., 2011). There is growing evidence of the extensive occurrence of OPFRs in various environmental media as well as human urine and milk (Cristale and Lacorte, 2013; Hoffman et al., 2014; Marklund et al., 2005; Sundkvist et al., 2010; Van den Eede et al., 2013). Because of their wide application in consumer products and building materials, OPFRs in the indoor environment have received significant attention. A number of studies concerning the occurrence of OPFRs in dust or air in homes, offices, and cars have found that OPFRs show significantly higher levels than BFRs in many countries (Ali et al., 2012; Brommer et al., 2012; Fromme et al., 2014). Indoor dust is a crucial daily exposure source of OPFRs for humans, especially for children. Significant correlations between the metabolite levels in children’s urine and the dust or air concentrations in daycare centers have been observed for some OPFRs by Fromme et al. (2014). OPFRs are reported to be easily absorbed after ingestion and inhalation (EU, 2008, 2009; HSDB, 2013). While evidence of the toxicological effects of OPFRs on human health is rare, animal experiments revealed that TCEP, TPhP and tricresyl phosphate (TCP) are neurotoxic and carcinogenic in animals, and TDCP and tris(2-butoxyethyl) phosphate (TBEP) have adverse effects on the liver and kidneys (ATSDR, 2012; EU, 2008, 2009; UKEA, 2009). These results raise concerns about the health risk of exposure to OPFRs. OPFRs have been used in diverse products for decades, including electrical and electronic equipment (Van der Veen and de Boer, 2012). Therefore, electrical and electronic waste (e-waste) may be a significant potential source of OPFRs. Much of the e-waste generated in developed countries ends up in developing countries, where e-waste is dismantled in a primitive way (Tian et al., 2011). Numerous studies have revealed the serious environmental contamination resulting from BFRs and heavy metals released from dismantling e-waste in developing regions (Chen et al., 2014; Luo et al., 2009; Wu et al., 2008; Zheng et al., 2010). At an e-waste site in China, Bi et al. (2010) found that TPhP was one of the major components of the organic matter found in particles emitted during printed circuit board recycling. To our knowledge, however, little is known about the environmental occurrence of OPFRs associated with e-waste recycling. Moreover, China is a large FR consumer because of its rapid economic development, and the demands for OPFRs are expected to increase approximately 15% annually (Ou, 2011). Nevertheless, limited data on the environmental contamination levels of OPFRs have been reported. In the present study, we measured the concentrations of a number of OPFRs in indoor dust in the rural region (including e-waste and non-e-waste areas) and in the urban region (including homes and college dormitory rooms) in southern China. We compared the distribution patterns of OPFRs in the four microenvironments and explored their sources in indoor dust. Moreover, human exposure to these chemicals through dust ingestion was estimated to understand the health risk to the residents posed by OPFRs.

2. Materials and methods 2.1. Sample collection Indoor dust samples were collected from four microenvironments in two regions: homes and college dormitories in Guangzhou City (urban region) and e-waste recycling workshops and homes in Qingyuan (rural region) in southern China. Guangzhou is a metropolis located in the Pearl River Delta region, an important city cluster of China, and has a population of 13 million. Qingyuan, located north of Guangzhou, is a much less developed region where one of the largest e-waste recycling sites in China is located (Fig. S1). The indoor dust samples (mainly from furniture and floors of the bedroom and living room) were collected between September, 2013, and March, 2014, using a vacuum cleaner. The urban house dust samples (n = 11) were collected from different districts, and dormitory samples (n = 15) were all collected from Sun Yat-sen University. Seventeen dust samples were obtained from the family-run workshops in several villages in Qingyuan, where e-waste recycling has existed for some decades. As a comparison, dust samples (n = 25) were also collected from villages near the e-waste recycling villages (with distance of 2–3 km). 2.2. Sample preparation and analysis The dust samples were sieved through a stainless steel sieve (100-lm mesh) to remove larger debris. Samples of approximately 0.2 g were spiked with surrogate standard (tri-n-butyl phosphate (TnBP-d27)) and Soxhlet-extracted with a mixture of acetone and hexane (1:1 v:v) for 48 h. Extracts were concentrated to 1 mL using a rotary evaporator and then further purified and fractionated by solid-phase extraction on a Florisil cartridge (Supelclean ENVIFlorisil, 3 mL 500 mg 1) from Supelco (Bellefonte, USA). The cartridge was pre-cleaned with 8 mL ethyl acetate and 6 mL hexane separately, and then concentrated extracts were eluted with 10 mL hexane and 8 mL ethyl acetate, respectively. The effluents of ethyl acetate containing OPFRs were then evaporated to near dryness by a gentle nitrogen stream and re-dissolved in 300 lL isooctane. Prior to injection, a quantitative standard (TPhP-d15) was added to each sample. 2.3. Instrumental analysis The analysis of OPFRs was performed with a Shimazu 2010 gas chromatograph coupled to a mass spectrometer (GC/MS) with an electron impact ion source. A DB-5MS (30 m  0.25 mm  0.25 lm) capillary column was used, and injection of 1 lL sample was performed with an automatic sampler using the splitless injection mode. The injection temperature was set at 70 °C and ramped to 300 °C with a sampling time of 1 min. Helium was the carrier gas with a flow rate of 1.0 mL min 1. Dwell times ranged from 20 to 30 ms. The ion source and interface temperatures were set at 200 °C and 290 °C, respectively. In total, 12 OPFRs were determined including triethyl phosphate (TEP), tri-isopropyl phosphate (TiPrP), TPhP, tri-n-butyl phosphate (TnBP), TCEP, TCPP, TDCP, TBEP, tri-npropyl phosphate (TnPP), ethylhexyl diphenyl phosphate (EHDPP), tri-(2-ethylhexyl) phosphate (TEHP), and TCP. 2.4. Quality control A procedural blank (pre-extracted filter) was analyzed with each batch of samples, and only TCEP was found in the five blanks (with a maximum concentration of 4.3 ng, less than 15% of the concentrations in the dust extracts). The concentrations in the sample

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extracts were blank-corrected using the corresponding blank values. The method limits of quantification (LOQs) were defined as the mean blank mass plus three standard deviations. The recoveries of surrogate standard (mean ± standard deviation) were 76.2 ± 9%. 2.5. Exposure assessment Human daily exposure doses to the OPFRs via house dust ingestion in the study area were assessed. The median and 95th percentile values of the OPFR concentrations in the dust samples were used in our assessment for plausible average and high-end exposure scenarios, respectively. Mean dust ingestion rates of 20 and 50 mg day 1 and high dust ingestion rates of 50 and 200 mg day 1 were used for adults and toddlers, respectively (Van den Eede et al., 2011). The absorption efficiency was assumed to be 100% due to the lack of information on human absorption efficiency (Jones-Otazo et al., 2005; Van den Eede et al., 2011). The average body weight (bw) of adults and toddlers (14 years old) were 63 and 13.8 kg, respectively, according to the 2010 National Physique Monitoring Bulletin in China. 3. Results and discussion 3.1. Concentrations The concentrations of OPFRs in the indoor dust are summarized in Table 1. The specific OPFR concentrations are given in Table S2 in the Supplementary material. OPFRs were found in all the samples of the areas studied. The OPFR concentrations were highest in the e-waste area, ranging from 3.30 to 70.0 lg g 1 with a median of 25.0 lg g 1. The concentrations in indoor dust in the rural homes (with a median of 7.48 lg g 1), urban homes (9.34 lg g 1), and college dormitories (11.0 lg g 1) were significantly lower than the levels in the e-waste area (p < 0.001, Mann–Whitney rank sum test). There were no statistically significant differences in the OPFR levels among these three areas (p > 0.199). The OPFR levels in the four microenvironments are also illustrated in Fig. S2. The results evidenced that e-waste recycling is a source of OPFRs in the surrounding environment. Most of the OPFRs detected in the present study are non-halogenated (Table S1). Their indoor concentrations in the e-waste area were, on average, 2.8 times higher than the indoor concentrations of the halogenated OPFRs (TCEP, TCPP, and TDCP). In the e-waste area, the highest concentrations were observed for TCP (median 9.51 lg g 1), which has a long history of applications mainly as a flame retardant in products such as wire and cable insulation, connectors, and automotive interiors as well as an additive in

Table 1 Summary of OPFRs levels in the house dust (lg g OPFRs

TEP TiPrP TnPP TnBP TCEP TCPP TDCP TBEP TPhP EHDPP TEHP TCP Total

hydraulic fluids (EU, 2009; HSDB, 2013). In the rural homes, the concentrations of halogenated and non-halogenated OPFRs were very close, with the highest concentration observed for TCEP (1.93 lg g 1). Compared to the e-waste area, there was an obvious increase in the halogenated OPFR levels and a decrease in the nonhalogenated levels in the urban homes and college dormitories, where the mean concentrations of halogenated OPFRs (5.35 lg g 1 and 8.29 lg g 1) were approximately 3 and 5 times higher than the non-halogenated OPFRs (1.95 lg g 1 and 1.74 lg g 1), respectively. The difference in the OPFR profiles between the e-waste recycling and the urban areas may indicate that different OPFR products were applied overseas and in southern China because a considerable proportion of the e-waste came from overseas. In the urban area, elevated levels as well as detection frequencies of TCEP were found, consistent with this flame retardant typically being added in flexible foams used in automobiles and furniture and in rigid foams used for building insulation rather than electronic equipment (IARC, 1990). In addition, the much lower levels of TCP in the urban indoor dust (especially in college dormitory dust where no TCP was detected) indicated that TCP is not currently used widely in household appliances in southern China. The OPFR levels in the college dormitories, where the quantities of electronic equipment and furniture are usually smaller than in homes, were similar to the OPFR levels in the urban homes. This result suggests that emissions from electronic equipment and furniture may be not a significant source of these OPFRs. Instead, other indoor products or building materials are possible potential emission sources. The smaller space of dormitory rooms (i.e., higher indoor air OPFR levels) leads to elevated levels in the indoor dust. The OPFR concentrations in the present study except for the ewaste area were lower than most values (medians) currently reported in home dust from other locations such as Sweden (27.1 lg g 1), Spain (33.0 lg g 1, mean), Belgium (13.1 lg g 1), US (22.3 lg g 1), Canada (41.2 lg g 1), and Japan (32.5 lg g 1) (Dodson et al., 2012; Fan et al., 2014; Garcia et al., 2007a; Marklund et al., 2003; Tajima et al., 2014;Van den Eede et al., 2011). Considerably higher levels of TBEP, which is released mainly from floor polishes, have been observed in indoor dust in daycare centers from Sweden (1600 lg g 1, median) and Germany (225 lg g 1) (Bergh et al., 2011; Fromme et al., 2014). Our levels were a little lower than the levels in the offices with mean values of 17.2–128 lg g 1 in Beijing, China (Cao et al., 2014), but higher than the levels in home dust from Kuwait (4.15 lg g 1), Pakistan (0.35 lg g 1), and New Zealand (2.42 lg g 1) (Ali et al., 2012, 2013). However, the mean levels of TCEP (5.18 lg g 1 in homes and 8.42 lg g 1 in college dormitories) in the urban dust in this study were higher than most values (0.04–5.6 lg g 1) in the

1

) from the four microenvironments of South China.

Rural e-waste workshop (n = 17)

Rural home (n = 25)

Range

Mean

Median

Range

Mean

Median

Urban home (n = 11) Range

Mean

Median

Urban college dormitory (n = 15) Range

Mean

Median

0.02–0.50 0.005–0.15 0.30–1.18 0.02–0.50 0.18–1.56 0.11–22.3 0.11–7.02 0.04–0.81 0.09–27.4 0.15–2.39 0.05–1.09 0.52–46.6 3.30–70.0

0.20 0.03 0.76 0.30 0.90 7.18 0.85 0.27 6.70 0.78 0.33 15.3 33.6

0.17 0.02 0.71 0.28 0.93 4.77 0.41 0.24 4.27 0.58 0.25 9.51 25.0

0.03–0.41 0.01–0.18 0.21–2.03 0.04–1.46 0.05–9.36 0.24–10.7 nd 2.77 0.03–1.76 0.26–5.34 0.06–1.28 0.08–1.85 nd 3.65 2.26–20.7

0.10 0.03 1.06 0.32 2.19 1.87 0.33 0.35 1.42 0.42 0.35 0.61 9.03

0.06 0.02 0.93 0.14 1.93 1.22 0.15 0.20 1.09 0.31 0.19 nd 7.48

0.02–0.24 0.004–0.02 0.50–1.00 0.03–0.15 1.55–9.70 0.16–2.93 nd 9.63 nd 3.05 0.01–0.80 0.03–3.47 0.03–1.37 nd 7.74 4.45–27.5

0.12 0.01 0.71 0.08 5.18 0.83 1.26 0.58 0.28 0.76 0.27 0.84 10.9

0.11 0.01 0.65 0.08 3.78 0.75 0.13 0.32 0.15 0.36 0.14 nd 9.34

0.03–0.94 0.01–0.09 0.35–2.75 0.06–0.14 2.78–20.8 0.06–2.30 0.06–3.71 0.04–0.77 0.02–0.94 nd 0.57 nd 0.32 nd 4.08–25.7

0.29 0.03 0.68 0.10 8.42 0.66 0.44 0.27 0.20 0.26 0.16 nd 11.50

0.17 0.02 0.52 0.10 7.94 0.48 0.13 0.28 0.12 0.27 0.16 nd 11.0

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literature, possibly suggestive of its large-scale use in southern China. The generally relatively lower levels of OPFRs in China may be a result of the continuous use of BFRs (such as deca-BDE and alternative decabromodiphenyl ethane products), which remain the major FRs in China with annual consumption of 150 000 tones (Ou, 2011; Xiao, 2006). As a comparison, the consumption of BFRs in Europe decreased from 56 000 tons in 2005 to 45 000 tones in 2008 (Ou, 2011). To our knowledge, data from other e-waste recycling sites have not been published. The median OPFR concentrations (25.0 lg g 1) in the e-waste area were higher than the median OPFR concentrations found in electronics stores and other stores (16.5 lg g 1) in Belgium (Van den Eede et al., 2011).

3.2. Compositions, correlations, and sources The composition profiles of the 12 OPFRs in indoor dust in the four microenvironments are depicted in Fig. 1. In the e-waste area, TCP (40.7 ± 16.9%), TCPP (21.0 ± 11.4%), and TPhP (18.9 ± 13.9%) dominated the OPFRs, and this profile clearly differed from the profiles of the other three areas because the obsolete electronic products recycled in this area are largely imported from overseas and had been used in the past. For instance, TCPP is an important OPFR in Europe, representing approximately 80% of the chlorinated PFR (Leisewitz et al., 2000). The production/usage volumes of TPhP were 20 000–30 000 t in Europe in 2000 and 4500–22 700 t in the US in 2004 (Van der Veen and de Boer, 2012). The figures for TCP in the US in 1998–2006 were 454–4500 t (Van der Veen and de Boer, 2012). All the three OPFRs have been used for decades in various products. In the urban areas, the OPFR profiles in homes and college dormitories were generally similar. TCEP was the most abundant OPFR in both indoor environments, accounting for 55.2 ± 22.6% and 71.2 ± 12.8% of the total OPFRs, respectively. Nevertheless, dust in urban homes has a higher contribution from TCP (4.5 ± 9.0%) than dormitory dust, where TCP was not detected. Reported applications of TCP in China include use in polyvinyl chloride polymer, thermoplastic resin, and lubricating oil. This finding implies that TCP is not used in large quantities in household products in southern China. The composition profiles in the rural homes, where TCEP, TnPP, TCPP, and TPhP constituted the majority of OPFRs (71.9%), were different from the composition profile in both the e-waste and urban areas (Fig. 1). TCP probably has similar applications in the rural and urban areas (with comparable average contributions), whereas TCEP is obviously used less extensively in the rural area than in the urban area, both of which released TCEP mainly from indoor products. The percentage contributions of TPhP (15.5 ± 6.0%) and TCPP (18.3 ± 9.2%) in the rural area were comparable to the percentage contributions in the e-waste area and much higher than those

Fig. 1. The composition profiles of OPFRs in indoor dust in e-waste workshops, rural homes, urban homes, and urban college dormitories in southern China.

in the urban area. Their occurrence in the rural indoor dust may originate from e-waste recycling, with TPhP and TCPP subsequently transported to the surroundings. The results indicated that indoor dust OPFRs in the rural area may be derived both from the nearby e-waste area via atmospheric transport and from household products in homes. However, the profile in the rural area could be characteristic of OPFRs used in the rural areas. The differences in the furniture, interior decoration, and building materials between the urban and rural areas are likely the main reason for the different profiles. Distinct OPFR profiles have been reported in indoor dust in previous studies. TPhP was found to be the dominant OPFR in Boston indoor dust in the US (Stapleton et al., 2009). TBEP was the most abundant OPFR in some European countries (Garcia et al., 2007b; Marklund et al., 2003; Tajima et al., 2014; Van den Eede et al., 2011) but shows minor contributions in all the dust in the present study. Cao et al. (2014) found that TCCP and TCEP dominated the OPFRs in the office dust in Beijing, China (Cao et al., 2014). The diverse applications of TCCP and TCEP in household products and building materials in different regions are responsible for the different distribution patterns. In general, most of the OPFRs in the present study showed no significant correlations with one another (Table S3), possibly due to their diverse applications in commercial products (i.e., different sources) as well as their different physicochemical properties (i.e., different environmental behavior). For example, TPhP and TCPP with vapor pressures of 3.87 and 0.027 Pa, respectively, are much more volatile than TCP (with vapor pressure of 2.4  10 5 Pa) (Brozena et al., 2014; EU, 2009). In the e-waste area, the predominant TCP had no correlation with TBEP, TCEP, and TnPP (r < 0.245, p > 0.344), suggesting different sources for these chemicals in the area, as discussed above. Significant correlations were found between TCP and TnBP, TPhP, and TCPP (r > 0.699, p < 0.002) and moderate correlations with others. These OPFRs with moderate correlations may have similar sources, but their different environmental behaviors may have hindered good correlations. Of the five major OPFRs in the rural dust, significant correlations were observed among TCEP, TCPP, and TPhP (r > 0.444, p < 0.026). These correlations imply that TCPP and TPhP may be derived more from household products than from e-waste recycling, as TCEP could be an indicator pollutant from household products. Significant correlations existed for only a few OPFRs in the urban dust. 3.3. Assessment of daily intake The estimated daily intakes (EDIs) of the OPFRs for adults and toddlers under different scenarios in the four areas are shown in Table 2. The EDIs for adults and toddlers in the e-waste area were 7.02 and 80.2 ng kg 1 bw-day, respectively, substantially higher than the EDIs for people in the urban area (2.06 and 23.5 ng kg 1 bw-day) and rural area (1.98 and 22.6 ng kg 1 bw-day) estimated by the mean dust ingestion rates and the median OPFR concentrations. The EDIs for people in college dormitories were estimated only for adults (3.23 ng kg 1 bw-day). However, considering the poor sanitary conditions in the rural area, local people are very likely to have high dust ingestion rates. Thus, EDIs of 4.95– 17.6 ng kg 1 bw-day for average adults and 90.5–321 ng kg 1 bw-day for toddlers in this rural area are suggested. People’s EDIs of OPFRs via indoor dust ingestion in the study areas were all under the reference doses (RfDs) of daily oral OPFR exposure (Table 2), suggesting a low risk of exposure to OPFRs. However, some toddlers may have high intakes of TCP (614 ng kg 1 bw-day, nearly half of the RfD). TCP is considered to have possible adverse effects on fertility (Fang et al., 2003; NTP, 1990), and it is toxic to the central nervous system (Bolgar et al.,

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C.-T. He et al. / Chemosphere 133 (2015) 47–52 Table 2 Summary of estimated OPFRs intakes (ng kg China.

1

bw-day) of adults and toddlers via house dust ingestion in the e-waste, rural, urban areas, adults in college dormitories in southern

E-waste area OPFRs

a b

RfDa

Rural area

Urban area

College dormitory

Toddler

Adult

Toddler

Adult

Toddler

Adult

Adult

median 95th percentile

median 95th percentile

median 95th percentile

median 95th percentile

median 95th percentile

median 95th percentile

median 95th percentile

(Mean dust ingestion, 20 mg day 1 for adult and 50 mg day 1 for toddler)b TEP n.a 0.61 1.67 0.05 0.15 0.21 1.34 TiPrP n.a 0.06 0.33 0.01 0.03 0.06 0.30 TnPP n.a 2.56 3.89 0.23 0.34 3.39 6.37 EHDPP n.a 2.10 6.95 0.18 0.61 1.11 4.22 TEHP n.a 0.89 3.77 0.08 0.33 0.69 4.84 TnBP 2400 1.00 1.73 0.09 0.15 0.51 2.34 TCEP 2200 3.36 5.33 0.29 0.47 7.00 19.1 TCPP 8000 17.3 75.4 1.51 6.61 4.43 16.6 TBEP 1500 0.87 1.78 0.08 0.16 0.71 4.67 TPhP 7000 15.5 74.9 1.36 6.57 3.96 10.4 TDCP 1500 1.49 9.08 0.13 0.80 0.56 3.55 TCP 1300 34.5 154 3.02 13.5 0.00 11.9 Total 80.2 338 7.02 29.7 22.6 85.6

0.02 0.01 0.30 0.10 0.06 0.04 0.61 0.39 0.06 0.35 0.05 0.00 1.98

0.12 0.03 0.56 0.37 0.42 0.21 1.68 1.46 0.41 0.91 0.31 1.04 7.50

0.40 0.04 2.37 1.32 0.50 0.28 13.7 2.71 1.15 0.53 0.47 0.00 23.5

0.85 0.05 3.42 11.0 3.28 0.54 34.6 7.32 7.01 2.64 23.5 15.4 110

0.03 0.00 0.21 0.12 0.04 0.02 1.20 0.24 0.10 0.05 0.04 0.00 2.06

0.07 0.00 0.30 0.97 0.29 0.05 3.03 0.64 0.61 0.23 2.06 1.35 9.61

0.06 0.01 0.16 0.09 0.05 0.03 2.52 0.15 0.09 0.04 0.04 0.00 3.23

0.28 0.02 0.44 0.16 0.09 0.04 4.79 0.51 0.16 0.21 0.61 0.00 7.32

(High dust ingestion, 50 mg day 1 for adult and TEP n.a 2.42 6.68 0.13 TiPrP n.a 0.24 1.30 0.01 TnPP n.a 10.3 15.6 0.56 EHDPP n.a 8.40 27.8 0.46 TEHP n.a 3.55 15.1 0.19 TnBP 2400 4.00 6.92 0.22 TCEP 2200 13.5 21.3 0.74 TCPP 8000 69.1 302 3.79 TBEP 1500 3.48 7.10 0.19 TPhP 7000 61.9 300 3.39 TDCP 1500 5.97 36.3 0.33 TCP 1300 138 614 7.55 Total 321 1353 17.6

0.05 0.01 0.74 0.24 0.15 0.11 1.53 0.97 0.16 0.87 0.12 0.00 4.95

0.29 0.06 1.39 0.92 1.06 0.51 4.19 3.64 1.02 2.27 0.78 2.61 18.8

1.59 0.15 9.47 5.26 2.00 1.10 54.8 10.8 4.58 2.12 1.89 0.00 93.8

3.39 0.22 13.7 44.1 13.1 2.17 138 29.3 28.1 10.6 94.0 61.7 439

0.09 0.01 0.52 0.29 0.11 0.06 3.00 0.59 0.25 0.12 0.10 0.00 5.14

0.19 0.01 0.75 2.41 0.72 0.12 7.57 1.60 1.54 0.58 5.15 3.38 24.0

0.14 0.02 0.41 0.21 0.13 0.08 6.30 0.38 0.22 0.09 0.11 0.00 8.08

0.69 0.05 1.10 0.40 0.23 0.10 12.0 1.28 0.41 0.54 1.52 0.00 18.3

200 mg day 0.37 0.07 0.85 1.52 0.83 0.38 1.17 16.5 0.39 16.4 1.99 33.6 74.1

1

for toddler) 0.83 5.37 0.26 1.19 13.5 25.5 4.42 16.9 2.74 19.4 2.02 9.37 28.0 76.6 17.7 66.5 2.85 18.7 15.8 41.4 2.23 14.2 0.00 47.6 90.5 343

Reference doses (ng kg 1 bw-day), calculated by Van den Eede et al. (2011). Data from Van den Eede et al. (2011).

2008). Although the EDIs of most of the OPFRs studied in the current study were under their RfDs, the risk of exposure of children to OPFRs in the e-waste area is still a concern, considering additional intake from other sources such as food and air inhalation and the potential high dust ingestion of children in this area.

Supplementary data associated with this article can be found, in the online version, at http://dx.doi.org/10.1016/j.chemosphere. 2015.03.043.

4. Conclusions

References

The concentrations and compositions of OPFRs were investigated in indoor dust from four microenvironmental categories in southern China. The OPFR concentrations in the e-waste area were significantly higher than the OPFR concentrations in the other three areas. The levels of OPFRs in southern China were generally lower than most values in other locations because of the ongoing wide use of BFRs in China. The composition profiles of OPFRs in the e-waste, urban, and rural areas generally reflected three different OPFR sources to the indoor environment (i.e., e-waste recycling, household products/building materials in urban areas, and household products in rural areas). Human exposures to the OPFRs via dust ingestion were all under the reference doses, suggesting a low risk for the population in southern China. However, the exposure of young children in the e-waste area may be substantially high if considering exposure from all sources, and an assessment of the overall health risk in this area is needed. Acknowledgments This study was financially supported by the National Science Foundation of China (Nos. 41230639, 21307037, and 41273115) and the Science and Technology Planning Project of Guangdong Province (2010B080703035).

Appendix A. Supplementary material

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