Indoor Dust Ingestion Research Articles

Bisphenol S and Its Chlorinated Derivatives in Indoor Dust and Human Exposure.

Bisphenol S (BPS), an environmental endocrine disruptor, has been identified in global environmental matrices. Nevertheless, limited studies have investigated the presence of chlorinated analogues of BPS (Clx-BPSs) with potential estrogenic activities in environmental matrices. In this study, the occurrence of BPS and five types of Clx-BPSs was characterized in indoor dust (n = 178) from Hangzhou City. BPS was measurable in 94% of indoor dust samples, with an average level of 0.63 μg/g (<LD-2.4 μg/g). Among the detected Clx-BPSs homologues, Cl1-BPS (2-chloro-4-(4-hydroxyphenyl)sulfonylphenol; detection frequency 70%), Cl2-BPS-2 (2-chloro-4-(3-chloro-4-hydroxyphenyl)sulfonylphenol; 65%), and Cl2-BPS-1 (2,6-dichloro-4-(4-hydroxyphenyl)sulfonylphenol; 61%) were among the frequently detected Clx-BPSs. Cl1-BPS was the most abundant analyte, with an average of 0.048 μg/g (<LD-0.24 μg/g), followed by Cl2-BPS-1 (0.035 μg/g, <LD-0.14 μg/g), and Cl2-BPS-2 (0.031 μg/g, <LD-0.13 μg/g). Significant correlations in indoor dust concentrations were observed between BPS and Cl1-BPS (p < 0.01), as well as between BPS and Cl2-BPS-1 (p < 0.01). Moreover, an estimation was made for the total daily intake of Clx-BPSs via the ingestion of indoor dust by infants, children, and adults. This study presents the first evidence of the existence of Clx-BPSs in indoor dust, concurrently highlighting the necessity to address their potential human exposure risks.

Occurrence of p-phenylenediamine antioxidants (PPDs) and PPDs-derived quinones in indoor dust

The p-phenylenediamine antioxidants (PPDs) have been widely detected in various dust samples. Nevertheless, the knowledge on occurrence of their environmental transformation products, PPD-derived quinones (PPDQs), in indoor dust remains limited. In this study, indoor dust samples (n = 97) were collected from Hangzhou, China, and analyzed for PPDs and PPDQs. Results showed that nine PPDs were detected in indoor dust samples, with the total concentrations of 1.7–223 ng/g. N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine (6PPD, mean 17 ng/g) was the predominant PPDs in indoor dust, followed by N, N′-di(o-tolyl)-p-phenylenediamine (DTPD, 8.6 ng/g) and N-(1,3-dimethylbutyl)-N′-(p-tolyl)-p-phenylenediamine (DMTPD, 4.7 ng/g). Five PPDQs were detected in indoor dust samples. Among detected PPDQs, 6PPDQ (14 ng/g, 0.33–82 ng/g) had the highest mean concentration, followed by DTPDQ (5.9 ng/g, < LOD–31 ng/g) and DPPDQ (2.2 ng/g, < LOD–11 ng/g). We also estimated the daily intake (DI) of PPDs and PPDQs through indoor dust ingestion. Infants had higher mean DIs of PPDs and PPDQs than children and adults. Notably, to our knowledge, this study first reports the occurrence of three novel PPDs and four novel PPDQs in indoor dust samples. More studies are needed to reveal the potential human health risks of exposure to these newly identified chemicals.

Occurrence, time trends, and human exposure of siloxanes and synthetic musk compounds in indoor dust from Korean homes

Siloxanes and synthetic musk compounds (SMCs) have been widely used as additives in household and personal care products. Humans are easily exposed to siloxanes and SMCs originating from these products through ingestion and dermal absorption of indoor dust. In the present study, indoor dust samples were analyzed for 19 siloxanes (cyclic and linear) and 12 SMCs (polycyclic, macrocyclic, and nitro musks) to assess their occurrence, time trends over time, source, and health risks. A total of 18 siloxanes and 10 SMCs were detected in all indoor dust samples obtained from 2011⎯2021, indicating widespread and long-term contamination. Higher detection frequencies and concentrations were associated with siloxanes and SMCs with higher use and strong resistance against degradation processes. Indoor dust samples were dominated by linear siloxanes (L11–L13), 1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta-(g)-2-benzopyran (HHCB), musk ketone (MK), and 7-acetyl-1,1,3,4,4,6-hexamethyl-1,2,3,4-tetrahydronaphthalene (AHTN). The frequent use of household and personal care products is likely an important source of siloxane and SMC contamination in indoor environments. The concentrations of siloxanes and SMCs in indoor dust increased from 2011 to 2021, particularly, those of linear siloxanes, reflecting the impact of regulatory actions addressing cyclic siloxanes. The profiles of siloxanes remained stable throughout the study period, whereas those of SMCs shifted from nitro to polycyclic musks. The estimated daily intakes (EDIs) of siloxanes and SMCs arising from ingestion were greater than from dermal absorption of indoor dust. The EDIs of siloxanes and SMCs associated with indoor dust indicated that children are exposed to these pollutants.

Evaluation of the oral bioaccessibility of legacy and emerging brominated flame retardants in indoor dust.

Indoor dust is the main source of human exposure to brominated flame retardants (BFRs). In this study, in vitro colon-extended physiologically-based extraction test (CE-PBET) with Tenax as a sorptive sink was applied to evaluate the oral bioaccessibility of twenty-two polybrominated diphenyl ethers (PBDEs) and seven novel BFRs (NBFRs) via indoor dust ingestion. The mean bioaccessibilities of two NBFRs pentabromotoluene (PBT) and 1,2-Bis(2,4,6-tribromophenoxy) ethane (BTBPE) were first proposed, reaching 36.0% and 26.7%, respectively. In order to maintain homeostasis of the gastrointestinal tract, 0.4g Tenax was added in CE-PEBT, which increased BFRs bioaccessibility by up to a factor of 1.4-1.9. The highest bioaccessibility of legacy PBDEs was tri-BDEs (73.3%), while 2-ethylhexyl-tetrabromo-benzoate (EHTBB), one of penta-BDE alternatives, showed the highest (62.2%) among NBFRs. The influence of food nutrients, liquid to solid (L/S) ratio, and octanol-water partition coefficient (Kow) on bioaccessibility was assessed. The oral bioaccessibility of BFRs increased with existence of protein or carbohydrate while lipid did the opposite. The bioaccessibilities of PBDEs and NBFRs were relatively higher with 200:1 L/S ratio. PBDEs bioaccessibility generally decreased with increasing LogKow. No significant correlation was observed between NBFRs bioaccessibility and LogKow. This study comprehensively evaluated the bioaccessibilities of legacy and emerging BFRs via dust ingestion using Tenax-assisted CE-PBET, and highlighted the significance to fully consider potential influencing factors on BFRs bioaccessibility in further human exposure estimation.

Levels and health risk assessments of Phthalate acid esters in indoor dust of some microenvironments within Ikeja and Ota, Nigeria

The levels, profiles of Phthalate acid esters (PAEs) and their associated health risk in children and adults using indoor dust samples were assessed from nine (9) microenvironments in Nigeria. Six PAEs congeners were determined using Gas Chromatography–Mass Spectrometry and the human health risk assessments of PAEs exposure to children and adults were computed using the United States Environmental Protection Agency (USEPA) exposure model. The mean concentrations of the total PAEs (Σ6PAEs) in indoor dust across the study locations ranged from 1.61 ± 0.12 to 53.3 ± 5.27 μg/g with 72.0% of di-n-octyl phthalate (DnOP) as the most predominant contributor of PAEs in sample locations B, C, D, E, F and G. PAEs estimated daily intake results exceeded the USEPA value of 20 and 50 kg/bw/day for children and adults respectively in some locations. Non-carcinogenic risk exposure indicated no risk (HI < 1), while the carcinogenic risk was within the recommended threshold of 1.00 × 10–4 to 1.00 × 10–6 for benzyl butyl phthalate and bis-2-ethylhexyl phthalate. From our findings, lower levels of PAEs were observed in locations with good ventilation system. Also, the human health risk evaluation indicated indoor dust ingestion as the dominant exposure route of PAEs for both children and adults, while the children were at a higher risk of PAEs exposure. To protect children susceptible to these endocrine-disrupting pollutants, soft vinyl children’s toys and teething rings should be avoided. Appropriate policies and procedures on the reduction of PAEs exposure to humans should be enacted by all stakeholders, including government regulatory agencies, industries, school administrators and the entire community.

Advancing Methodologies Used in Trace Element-Based Mass Balance Studies to Separately Estimate Soil and Dust Ingestion Rates for Children

Historically, soil ingestion rate estimates were based on trace element-based mass balance (MB) study results. These were used in assessing exposures and health risks for children residing in Superfund or chemically contaminated communities. However, soil and dust can have considerable differences with respect to their sources, chemical, physical, and toxicological characteristics. Unfortunately, the MB approach is incapable of disentangling dust ingestion rates from soil ingestion rates. Alternative methods, such as activity pattern and biokinetic modeling techniques, have also been used to predict soil and dust ingestion rates. The results from these studies differed from those obtained from the MB studies. This research evaluated the MB methodology and formulated a physical model which characterized the environmental and behavioral determinants of soil and dust ingestion exposures by children. This new approach explicitly separates outdoor soil exposures from the indoor tracked-in soil portion of the dust and total dust exposures by utilizing information from five key MB studies along with new information derived from the SHEDS-Soil/Dust time-activity pattern-based modeling runs. Application of this new hybrid methodology showed that the predicted mean soil ingestion rates are 30%-70% less than the “total soil” ingestion rates obtained from the selected MB studies. In contrast, most of the predicted dust ingestion rate estimates were typically greater than the predicted soil ingestion rates. Moreover, the predicted total soil plus dust ingestion rates were found to be mostly higher (by ≤ 60%) than the MB-based “total soil” ingestion rates. Except for one study these results were higher than the results produced by the stand-alone SHEDS-Soil/Dust model runs. Across the MB studies analyzed, predicted outdoor soil ingestion rate contributions to “total soil” ingestion rates varied between 29% and 70% while the tracked-in soil portion of the indoor dust ingestion rates varied between 30% and 71%.

Presence, source attribution, and human exposure to organophosphate esters in indoor dust from various microenvironments in Nigeria

Very few studies have reported the presence of the organophosphate esters (OPEs) in African indoor microenvironments. We therefore document here, the concentrations, profiles, and human exposure to eight organophosphate esters (OPEs) for the first time in indoor dust from various microenvironments in Nigeria, specifically: cars/buses (n = 10), homes (n = 20), offices (n = 20), and medical centres (n = 14). The concentrations of OPEs in these indoor dust samples were among the lowest reported internationally. Concentrations of ∑8OPEs varied substantially between individual samples and the predominant OPEs were: tris(2-butoxyethyl) phosphate (TBOEP) (detection frequency (DF) = 90–100%), tris(1-chloro-2-propyl) phosphate (TCIPP) (DF = 100%), and 2-ethylhexyl-diphenyl phosphate (EHDPP) (DF = 100%). There were no significant differences (P˃0.05) between ∑8OPEs concentrations in dust samples from cars/buses (average = 295 ng/g), offices (231 ng/g), homes (277 ng/g), and medical centres (127 ng/g). Concentrations of chlorinated OPEs: tris(2-chloroethyl) phosphate (TCEP), TCIPP, and tris(1,3-dichloro-2-propyl) phosphate (TDCIPP) were significantly correlated with those of triphenyl phosphate (TPhP), EHDPP, and TBOEP. Estimated daily intakes (EDI) of target OPEs via indoor dust ingestion and dermal absorption were lower than the corresponding reference dose (RfD) values, indicating that exposure to the studied OPEs in the indoor environment does not pose a significant health risk for the general population in Nigeria, even under a high-end exposure scenario.

Concentrations of organophosphate esters in drinking water from the United Kingdom: Implications for human exposure

Data on the presence of organophosphate esters (OPEs) in drinking water and its significance as a pathway of exposure are limited. In this study, we measure for the first time, concentrations of eight OPEs in 50 UK drinking water samples. Arithmetic mean concentrations of ∑8OPEs were: 6.4 and 11 ng/L in bottled (n = 25) and tap water samples (n = 25), respectively. Concentrations of ∑8OPEs in tap water (mean: 11 ng/L) exceed significantly those in bottled water (mean: 6.4 ng/L) (p ˂ 0.01). Moreover, UK tap water is more contaminated with chlorinated, aryl-, and alkyl-OPEs than bottled water. The predominant OPEs detected were: tris (butoxyethyl) phosphate (TBOEP), tris (2-chloroethyl) phosphate (TCEP), and tris(2-chloroisopropyl) phosphate (TCIPP) with arithmetic mean concentrations in the two water sample types ranging between (3.5–3.8 ng/L), (0.60–3.0 ng/L), and (1.02–2.9 ng/L), respectively. Estimated daily intakes (EDIs) (mean and high-end exposure) via drinking water for different sectors of the UK population were: infants (0.93 and 6.4 ng/kg bw/day) ˃ toddlers (0.46 and 3.1 ng/kg bw/day) ˃ children (0.35 and 2.3 ng/kg bw/day) ˃ adults (0.28 and 2.1 ng/kg bw/day). Based on these data, exposure to Σ8OPEs via drinking water is much lower than via: food, indoor dust ingestion, inhalation, and dermal uptake for adults and toddlers. Reassuringly, our EDIs were lower than relevant reference dose (RfD) values. However, combining our drinking water ingestion data with exposure via other pathways revealed overall exposure to 2-ethylhexyl diphenyl phosphate (EHDPP) and TCIPP to approach health-based limit values for UK toddlers under a high-end exposure scenario.

Determination of glyphosate and AMPA in indoor settled dust by hydrophilic interaction liquid chromatography with tandem mass spectrometry and implications for human exposure

The widespread application of glyphosate leads to significant contamination of outdoor environmental compartments, notably air and soil, which can contaminate indoor air and dust. This study assessed the contamination of indoor household dust for the first time in France and potential exposure to glyphosate through the inadvertent ingestion of dust. A specific and new analytical method was developed using HILIC MS/MS (hydrophilic interaction liquid chromatography with tandem mass spectrometry) to measure polar pesticides, such as glyphosate, aminomethylphosphonic acid, and glufosinate, in indoor dust, with a low quantification limit (25 ng/g). The dust from vacuum cleaner bags of 60 rural and urban households (Brittany, France) was analyzed. All samples contained glyphosate (median 1675 ng/g for rural dwellings (n = 29), 457 ng/g for urban dwellings (n = 31)), more than 90 % contained aminomethylphosphonic acid, and none contained glufosinate. Concentrations were influenced by the rural or urban setting, the proximity of crops, and the use of weed killers on driveways or lawns. Glyphosate exposure via indoor dust ingestion was < 1 % of both acceptable daily intake and dietary intake. However, the high quantification limit of the glyphosate concentration in the food analysis method probably leads to overestimation of the dose from food.

Polyhalogenated carbazoles in indoor dust from Hangzhou, China

Carbazoles (CZ) and polyhalogenated carbazoles (PHCZs), showing dioxin-like toxicity, have gained increasing attention in recent years as novel persistent organic pollutants. However, the occurrence of these chemicals in indoor dust from China remains not well known. In this study, CZ and 11 chloro/bromo CZs were analyzed in indoor dust samples collected from residential houses in rural (n = 51) and urban (n = 55) regions of Hangzhou, China. CZ was detected in all indoor dust samples, with the concentrations of 0.81–18 ng/g (mean 5.4 ng/g). All 11 measured PHCZs were detected in indoor dust samples, showing the detection frequency of 7.3–96 %. This means that general populations had wide exposure to CZ and PHCZs through indoor dust ingestion. 3,6-dichlorocarbzole (36-CCZ) and 3,6-dibromocarbazole (36-BCZ) were the predominant PHCZs in indoor dust, having comparable mean concentrations of 1.2 ng/g, followed by 3-monobromocarbazole (3-BCZ; mean 0.66 ng/g, range < LOD–2.1 ng/g) and 1,3,6-tribromocarbazole (136-BCZ; 0.36 ng/g, < LOD–1.0 ng/g). Indoor dust concentrations of 3-BCZ, 36-BCZ, and 1,3,6,8-tetrabromocarbazole in urban regions were significantly (p ≤ 0.01–0.035) higher than that in rural regions. Daily intakes (DIs) of CZ and PHCZs through indoor dust ingestion were estimated for general Chinese population. Among PHCZs, 36-CCZ and 36-BCZ (mean 1.4–3.4 pg/kg bw/day) had the highest mean DIs, followed by 3-BCZ (0.77–1.9 pg/kg bw/day) and 136-BCZ (0.42–1.0 pg/kg/day). To our knowledge, this is the first study reporting the concentrations of CZ and PHCZs in indoor dust from China, which contributes to the better understanding of the sources of human exposure to CZ and PHCZs.

Determination of Bisphenol in Indoor Dust Samples by Liquid Chromatography in Combination with Quadrupole Mass Spectrometry (LC-MS/MS)

This study has focused on the development of the method LC-MS/MS to determine 2,2-bis(4-hydroxyphenyl)propane (bisphenol A: BPA) and 4,4’-dihydroxydiphenylmethane (bisphenol F: BPF) in indoor samples by using ultrasonication extraction and solid-phase extraction for preparation. The chromatographic procedure was performed on Kinetex C18 2.1 x 150 mm, 2.6 µm column with mobile phases: 2 mM HCOONH4 in MeOH and H2O:MeOH (90:10,…). The method quantification limits (MQL) of BPA and BPF were 15.0 and 12.0 ng/g, respectively. The mean recoveries were 80.4% for BPA and 93.8% for BPF (RSD&lt;15%). The calibration curve for both BPA and BPF was linear over a concentration range of 1.0 to 500 ng/mL (R2 ≥ 0.999). Twenty-one samples were collected from private houses, laboratories, drug stores, and plastic recycling factories in Hanoi. BPA and BPF were found in dust samples with frequencies of 85.7 and 100%, respectively. Concentrations of BPA and BPF in dust samples were in the ranges of &lt;MQL–2230 ng/g (mean: 626) and &lt;MQL–149,000 ng/g (mean: 14,700), respectively. Based on the measured concentration, the human exposure to bisphenol via indoor dust ingestion was estimated for various age groups. The estimated exposure dose for people working at plastic recycling factories was the highest level (23.6 ng/kg-bw/day) but lower than the oral reference dose by the EPA and the European Food Safety Authority (50 µg/kg-bw/day).

Profiling of multiple classes of flame retardants in house dust in China: Pattern analysis and human exposure assessment

Legacy [e.g., brominated- (BFRs)] and alternative [e.g., organophosphate- (OPFRs) and nitrogenous- (NFRs)] flame retardants have a propensity to migrate out of consumer products, and thus are dispersed in indoor microenvironments. In this study, simultaneous presence of 11 BFRs, 18 OPFRs and 11 NFRs were measured in house dust collected from Tianjin, China. OPFRs were found at the highest concentrations, with a median value of 3200 ng/g, followed by NFRs (2600) and BFRs (1600). Tris(2-butoxyethyl) phosphate (median: 1800 ng/g), melamine (1100), and BDE-209 (870) were the top three most abundant chemicals in the respective groups. Location-specific patterns of flame retardant concentrations were found with 30%, 20% and 10% of samples were predominated by OPFRs, NFRs and BFRs, respectively, and the remaining samples contained by two or more of the chemical groups occurring concurrently. Network and cluster analysis results indicated the existence of multiple sources of flame retardants in the indoor microenvironment. Estimated human daily intakes via indoor dust ingestion were approximately several tens of ng/kg bw/day and were below their respective reference dose values. Our results indicate widespread occurrence of multiple flame retardant families in indoor dust and suggest need for continued monitoring and efforts to reduce exposures through dust ingestion.

Perfluoroalkyl and polyfluoroalkyl substances, bisphenol and paraben compounds in dust collected from residential homes in Klang Valley, Malaysia

Endocrine disrupting chemicals (EDCs) are a growing global concern due to their widespread use and potential harm to human and animal health. Several EDCs have been linked to cancer, obesity, and diabetes in children and adults. EDCs come from manufacturers or everyday products like cookware, textile, cosmetic, furniture, and plastic. Some EDCs are volatile and may be inhaled by the inhabitants where indoor exposure to EDCs is considered worse than outdoor exposure due to the limited and confined area allowing dermal contact and ingestion of EDCs. During the COVID-19 pandemic in 2020–2021, all Malaysians were confined to their homes, prompting the goal of this study to investigate EDCs in household dust collected from Klang Valley homes. A total of 57 dust samples were collected, filtered, and extracted using methanol. EDCs including perfluoroalkyl and polyfluoroalkyl substances (PFAS), bisphenol and parabens were identified and quantified in dust samples by liquid chromatography mass tandem spectrometry (LCMS/MS). The presence of perfluorooctanoic acid (PFOA), perfluorooctane sulfonic acid (PFOS), butylparaben (BuP), methylparaben (MeP), ethylparaben (EtP), and propylparaben (PrP) was detected in 50–100% of dust samples, with range of concentration of 0.31–3693.96 ng/g, indicating that these compounds are common in indoor dust. Methylparaben was the most prevalent EDC in collected dust samples with mean concentration at 148. 18 ng/g, accounting for 54% of the concentration distribution, followed by BuP and PFOA. There were regional differences in EDC profiles, with higher PFAS and paraben levels in urban areas such as Putrajaya, Kuala Lumpur, and Petaling. The estimated daily intake (EDI) of EDCs from indoor dust ingestion varied by age, with infants having a significantly higher EDI (p < .01) than children and adults. Despite safe for consumption (Hazard Quotient, HQ < 1), these findings provide a baseline for assessing PFAS, bisphenol, and paraben in indoor dust from Malaysian homes.

Occurrence and exposure assessment of microplastics in indoor dusts of buildings with different applications in Bushehr and Shiraz cities, Iran

The increase in annual usage of plastics for different purposes has led to an increase in microplastics (MPs) particles in various environments including inside of buildings. In the present study, levels and characteristics of MPs in the indoor dust of buildings with different uses including residential house, mosque, hospital, kindergarten, and university in two cities, Bushehr port and Shiraz in Iran, were determined. Thirty dust samples from various buildings were collected. The average numbers of MPs in the indoor dust of buildings of Shiraz and Bushehr were 90.8 and 80.8 items/mg, respectively. Fiber and polyethylene (PE) were the most common shape and polymer types of identified MPs, respectively. The highest number of MPs was observed in the indoor dust of kindergartens with a mean number of 121 items/mg in Bushehr and 104 items/mg in Shiraz. Except for mosques, a significant difference (p-value <0.05) were not observed between the MPs levels of buildings with similar applications in Bushehr and Shiraz cities. In addition, the high daily intake to MPs via indoor dust ingestion and inhalation were found for infants in kindergartens and mosques. The results of this study showed that MPs are present in high concentrations in indoor environments and may pose a high exposure risk for different age groups.

A review of organophosphate esters in soil: Implications for the potential source, transfer, and transformation mechanism.

Organophosphate esters (OPEs) are widely used around the world as flame retardants and plasticizers with a growing production in the last 15 years due to the phase-out of polybrominated diphenyl ethers. Multiple papers reported the occurrences of OPEs in various environmental matrices and elevated concentrations of OPEs (0.1-10,000ng/g dry weight) were documented in different types of soils which were regarded as both the "sink" and "source" of OPEs. In this study, the source, transfer, and transformation mechanisms of OPEs are systematically reviewed from the perspective of the soil environment. The wet/dry deposition, air-soil exchange, sewage irrigation, sludge application, and indirect oxidization of organophosphate antioxidants are the possible sources of OPEs in soil. Meanwhile, the OPEs in the soil environment may also migrate into other environmental media via plant uptake, air-soil exchange, desorption, and infiltration to cause relevant ecological risk, which depends much on the chemical properties of these compounds. The trimethylphenyl phosphate (TMPP) (mixture of isomers) and triphenyl phosphate (TPHP), which have strong hydrophobicity, pose a higher ecological risk for the soil environment than other OPEs. Further, the hydrolysis, indirect photolysis, and biodegradation of OPEs in the soil environment may be affected by the soil pH, organic acid, dissolved metals and metal oxides, active oxygen species, and microorganisms significantly. Besides that, the human exposure risks of OPEs from the soil are limited compared to those via indoor dust and food ingestion pathways. Finally, this study identifies the knowledge gaps and generated the future perspectives of the OPEs in soil.

Profiles of parabens, benzophenone-type ultraviolet filters, triclosan, and triclocarban in paired urine and indoor dust samples from Chinese university students: Implications for human exposure

Parabens, benzophenone (BP)-type UV filters, triclosan (TCS), and triclocarban (TCC) are commonly used in personal care products. Human exposure to these compounds has received increasing concern because of their adverse health effects. However, the levels of these chemicals in paired urine and indoor samples have never been simultaneously measured. In this work, eight parabens, eight BP-type UV filters, TCS, and TCC were measured in paired urine and indoor dust samples collected from university students and their dormitories in South China. The target analytes were commonly measured in urine (71%–100%) and indoor dust (30%–98%), with median concentrations ranging from 0.16 ng/mL to 19.3 ng/mL in urine and from <0.01 ng/g to 3700 ng/g in indoor dust samples. Females had high levels of most of these target compounds, and gender-related differences were found in the levels of most target analytes. Positive correlations were found in the levels of methylparaben, ethyl paraben, benzophenone-3, and TCS between urine and indoor dust samples. This finding suggested that indoor dust is an important source for human exposure to these compounds. The estimated daily intake (EDI) of these analytes in paired samples was also evaluated. The median EDI-urine values of target analytes varied in the range of 4.02–59,280 ng/kg bw/day. Females had higher median EDI-urine values for most of target analytes than males. In addition, the median EDI-indoor dust values of most target analytes in dust from female dormitories were higher than those in dust from male dormitories. Indoor dust ingestion only had minor contribution (<0.5%) to the total exposure. To the best of the authors' knowledge, this study is the first to simultaneously analyze the concentrations of parabens, BP-type UV filters, TCS, and TCC in the paired urine and indoor samples from university students in South China.

Occurrence of parabens, triclosan and triclocarban in paired human urine and indoor dust from two typical cities in China and its implications for human exposure

Parabens, triclosan (TCS) and triclocarban (TCC) are emerging endocrine disrupting chemicals, which are commonly used in personal care products and household applications in daily life. Due to their adverse health effects, human exposure to these chemicals has been a public concern. Despite evidence showing different exposure pathways of these chemicals, few studies have examined contribution of certain exposure to total human exposure. In this study, we measured six parabens, TCS and TCC in 129 indoor dust samples and these chemicals plus four paraben metabolites in 203 urine samples from two different cities in China (Suizhou, a typical small city in central China and Beijing, the capital of China). The median concentrations of ∑6Parabens (1050 ng/g) and ∑TCS + TCC (565 ng/g) in dusts from Beijing were 1.9–3.3 times higher than those from Suizhou (∑6Parabens: 314, ∑TCS + TCC: 294 ng/g). The ∑6Parabens in urines from Suizhou and Beijing were in the range of 0.208–645 and 0.455–2300 μg/g Creatinine (Cr), respectively. The ∑TCS + TCC concentrations in urine were 1–2 orders of magnitude lower than those found for ∑6Parabens. Comparatively, women had relatively higher body burden of parabens than men, which was more noticeable when considering the use of skin care products. In this regard, relatively higher levels of parabens were also found in women in couples. Positive correlations were found between concentrations of methyl-paraben (MeP) and ethyl-paraben (PrP) in paired dust and urine samples (p < 0.05). Human exposure to such chemicals was evaluated. Based on the measured concentrations in paired human urine and indoor dust samples, our results provided direct evidence that the contribution of indoor dust ingestion to the total exposure was minor. These findings are essential for clarifying the sources and potential exposure routes of these chemicals in humans.

Contamination status, emission sources, and human health risk of brominated flame retardants in urban indoor dust from Hanoi, Vietnam: the replacement of legacy polybrominated diphenyl ether mixtures by alternative formulations.

This study investigated the occurrence, distribution of several additive brominated flame retardants (BFRs) such as polybrominated diphenyl ethers (PBDEs) and some novel brominated flame retardants (NBFRs) in urban indoor dust collected from ten inner districts of Hanoi, Vietnam to assess the contamination status, emission sources, as well as their associated human exposure through indoor dust ingestion and health risks. Total concentrations of PBDEs and NBFRs in indoor dust samples ranged from 43 to 480 ng g-1 (median 170 ng g-1) and from 56 to 2200 ng g-1 (median 180 ng g-1), respectively. The most abundant PBDE congener in these dust samples was BDE-209 with concentrations ranging from 29 to 360 ng g-1, accounting for 62.6-86.5% of total PBDE levels. Among the NBFRs analyzed, decabromodiphenyl ethane (DBDPE) was the predominant compound with a mean contribution of 98.6% total NBFR amounts. Significant concentrations of DBDPE were detected in all dust samples (median 180 ng g-1, range 54-2200 ng g-1), due to DBDPE as a substitute for deca-BDE. Other NBFRs such as 1,2-bis(2,4,6-tribromophenoxy) ethane (BTBPE), pentabromoethylbenzene (PBEB) and 2,2',4,4',5,5'-hexabromobiphenyl (BB-153) were found at very low levels. Based on the measured BFR concentrations, daily intake doses (IDs) of PBDEs and NBFRs via dust ingestion at exposure scenarios using the median and 95th percentile levels for both adults and children were calculated for risk assessment. The results showed that the daily exposure doses via dust ingestion of all compounds, even in the high-exposure scenarios were also lower than their reference dose (RfD) values. The lifetime cancer risks (LTCR) were much lower than the threshold level (10-6), which indicated the acceptable health risks resulting from indoor BFRs exposure for urban residents in Hanoi.

Differences of bisphenol analogue concentrations in indoor dust between rural and urban areas

Bisphenol analogues (BPs) are widely applied in varying consumer products. Many studies have reported their presence in indoor dust samples from China. However, the differences in occurrence and concentration profiles of BPs in indoor dust between rural and urban areas are still not well characterized. In this study, eight BPs were measured in 60 indoor dust samples collected from rural and urban districts of Hangzhou, China. Bisphenol A (BPA; mean 1.8 μg/g, range 0.20–7.2 μg/g) was the predominant BP in indoor dust samples, accounting for mean 57% of the total BP (∑BP) concentration, followed by bisphenol S (BPS; 0.58 μg/g, <LOD–2.4 μg/g) and bisphenol AF (0.43 μg/g, <LOD–2.6 μg/g). Indoor dust samples from the urban areas (n = 27) contained significantly (p < 0.05) higher levels of ∑BPs, BPA, and BPS than that from the rural areas (n = 33). Comparatively, bisphenol F and bisphenol AP were more frequently detected in urban indoor dust samples. Daily intakes (DIs) of BPs through the indoor dust inhalation were estimated for infants, children, and adults. Infants had much higher (p < 0.01) DIs of BPs than children and adults, mainly owing to their lower body weights and higher indoor dust ingestion rates. To our knowledge, this is one of the first studies examining the regional differences of BP concentrations in indoor dust from China, which could contribute to the more accurate evaluation of human BP exposure through indoor dust intake.

Organophosphate flame retardants and diesters in the urine of e-waste dismantling workers: associations with indoor dust and implications for urinary biomonitoring.

Indoor dust ingestion is one of the main pathways for human exposure to organophosphate flame retardants (PFRs). The urinary concentrations of diesters (DAPs) are usually used as biomarkers to assess human exposure to PFRs. In this study, the PFR and DAP levels were measured in morning and evening urine samples of 30 workers from an e-waste dismantling site in southern China. The indoor dust samples were also collected from workshops and houses for analyzing associations between PFR and DAP levels in urine and dust. Tris(1-chloro-2-propyl) phosphate (TCIPP) and triphenyl phosphate (TPHP) were the dominant PFRs in dust, while bis(2-chloroethyl) phosphate (BCEP) and diphenyl phosphate (DPHP) were the major DAPs in dust. A significant positive correlation was observed between TPHP and DPHP concentrations in dust (p < 0.001), suggesting their potentially same source and the degradation of TPHP to form DPHP. TCIPP and tris(1,3-dichloro-2-propyl) phosphate (TDCIPP) were the predominant PFRs, and BCEP, bis(1,3-dichloro-2-propyl) phosphate (BDCIPP), and DPHP were the main DAPs in both the morning and evening urine samples. The DPHP levels in evening urine samples were significantly correlated with TPHP and DPHP levels (p < 0.01) in dust. A similar correlation was found for the BCEP levels in the evening urine samples and the TCEP and BCEP levels (p < 0.01) in dust. These results indicated that in addition to being biotransformed from their respective parent PFRs, direct ingestion from indoor dust could also be the potential source for urinary DPHP and BCEP. Since relatively low detection frequencies were observed for bis(1-chloro-2-propyl) phosphate (BCIPP) and bis(butoxyethyl) phosphate (BBOEP) in urine, they may not be the major metabolites of TCIPP and tris(2-butoxyethyl) phosphate (TBOEP), respectively, in the human body. However, BDCIPP can be considered a useful biomarker because it is a unique metabolite of TDCIPP and has high detection frequencies in urine samples. The results of this study indicated the limitations of solely using urinary DAPs as biomarkers for the evaluation of human exposure to PFRs, and certain PFRs as well as hydroxylated PFRs (OH-PFRs) should also be considered for urinary biomonitoring in future studies.