Occurrence and fate of organophosphate ester flame retardants and plasticizers in indoor air and dust of Nepal: Implication for human exposure

Organophosphate esters and their specific metabolites in chicken eggs from across Australia: Occurrence, profile, and distribution between yolk and albumin fractions

A substantial increase in the usage of organophosphate esters (OPEs) as flame retardants and plasticizers in rubbers, textiles, upholstered furniture, lacquers, plastics, building materials and electronic equipment has resulted in their increasing concentrations in the environment over time. However, little is known about the concentrations and fate of OPEs and their metabolites (mOPEs) in biota, including chicken eggs. The aim of this study was to understand the spatial variation in the concentrations in chicken eggs and the partitioning between yolk and albumin. In total, 153 chicken eggs were purchased across Australia and analysed for 9 OPEs and 11 mOPE. Most of the compounds were found to be deposited in egg yolk, where diphenyl phosphate (DPHP, 3.8 ng/g wet weight, median) and tris(2-chloroisopropyl) phosphate (TCIPP, 1.8 ng/g wet weight, median) were predominant mOPE and OPE, respectively. Moreover, no spatial differences in concentrations of OPEs and mOPEs in eggs purchased from different locations were found in this study. Although comparable levels of ∑OPEs were detected in egg yolk and albumin, much higher concentrations of ∑mOPEs were found in yolk than albumin. Meanwhile, a negative correlation (R² = 0.964, p = 0.018) was found between the molecular mass of analytes and partitioning coefficient of C_yolk/C_yolk+albumin (defined as chemical concentration in egg yolk divided by the sum of chemical concentrations in both yolk and albumin). These results indicate that n-octanol/water partition coefficients (log K_OW) may not be a crucial factor in the distribution of OPEs and mOPEs between egg yolk and albumin, which is important in understanding distribution of emerging organic contaminants in biota.

Distribution, source apportionment and ecological risks of organophosphate esters in surface sediments from the Liao River, Northeast China

A total of 24 surface sediment samples were collected from Liao River, Northeast China. The concentration, spatial distribution, potential source, and ecological risk of 13 organophosphate esters (OPEs) flame retardants and plasticizers were analyzed. The total concentrations of OPEs varied considerably, ranging from 19.7 to 234 ng g^-1 dry weight (dw), with the mean concentrations of 64.2 ± 52.2 ng g^-1 dw. The OPEs pollution was increasing from upstream to downstream of Liao River. Compared with other sediments of rivers and lakes all over the world, Liao River has been seriously contaminated by OPEs, especially tributyl phosphate (TNBP) and tri-butoxyethyl phosphate (TBOEP). TNBP was the most abundant OPEs, followed by TBOEP and triphenylphosphine oxide. Their mean relative contributions were 26.3%, 12.4% and 11.6%, respectively. Positive matrix factorization indicated that OPEs in sediments from Liao River might be derived from plastic, textile, and polyurethane foam, anti-foam agent, hydraulic fluids, and coatings, indoor release, and chemical process emission. The risk of potential adverse effects of each individually OPEs on aquatic organisms were low (risk quotient less than 0.1). 2-Ethylhexyl diphenyl phosphate was the main substance causing risk.

Organophosphate esters and their metabolites in paired human whole blood, serum, and urine as biomarkers of exposure

Although organophosphate diester (di-OPE) metabolites in urine are usually used to assess human exposure to organophosphate esters (OPEs), whether they can reflect human exposure to all OPEs with great differences in chemical structures and properties is still currently unclear. In this study, we detected sixteen OPEs and ten di-OPEs in 52 paired whole blood, serum, and urine samples collected in Beijing, China to investigate the correlations between different compounds and matrices, thus providing proper biomarkers of human exposure to OPEs. The order of the median concentrations of ∑OPEs was whole blood (8.63 ng/mL) > serum (5.71 ng/mL) > urine (0.396 ng/mL), while those of ∑di-OPEs followed the order of urine (16.6 ng/mL) > whole blood (5.97 ng/mL) > serum (3.70 ng/mL). Ethylhexyl diphenyl phosphate (EHDPP) and cresyl diphenyl phosphate (CDPP) were the dominant OPEs in both whole blood and serum samples and were significantly correlated between these two matrices. The distribution of OPEs in human blood was evaluated according to serum-to-whole blood concentration ratios (S:WB ratios). The median S:WB ratios of triethyl phosphate (TEP), tri-n-butyl phosphate (TnBP), bisphenol-A bis(diphenyl phosphate) (BABP), EHDPP, and CDPP were lower than 1, indicating that these OPEs preferred to accumulated in blood cells rather than in serum/plasma. Bis(2-ethylhexyl) phosphate (BEHP) was the major di-OPEs and was detected in almost all whole blood, serum and urine samples. The median whole blood: urine (WB:UR) ratios of di-OPEs were significantly and positively correlated with their logK_ow values, indicating that di-OPEs with low hydrophobicity were prone to excretion via urine. Based on the relationships between OPEs and di-OPEs in these matrices, the parent OPEs in whole blood can be recommended for use as alternative biomarkers of aryl-OPEs exposure in future human biomonitoring studies, in addition to metabolites in urine.

Elevated occupational exposure to chlorinated phosphate esters at a construction materials manufacturing plant

BACKGROUND

Numerous studies have documented that the general population is widely exposed to organophosphate esters (OPEs), yet studies on the emissions of OPEs in the industrial application processes and their occupational exposure are scarce. The aim of this study was to assess the exposure to OPEs for workers engaged in OPE-retarded construction material manufacturing plant in China.

METHOD

Paired dust samples (12 samples each time) from an OPEs retarded building materials manufacturing plant during the plant uptime and downtime have been analyzed for tris(2-chloroethyl)-phosphate (TCEP), tris(2-chloroisopropyl) phosphate (TCPP), and other commonly used OPEs. Moreover, nine OPEs metabolites (mOPEs) in urine samples (n = 42) from fourteen workers who engaged in this plant were also measured. The daily exposure doses to OPEs were estimated from the measured urinary concentrations of corresponding mOPEs.

RESULTS

Thirteen out of fourteen studied OPEs (except for tri-n-propyl phosphate, TnPP) were determined in all dust samples from the manufacturing plant, and TCEP and TCPP were the predominant compounds in dust collected from the plant uptime and downtime. Overall, the occupationally exposed population had significantly higher (p < 0.01) urinary levels of mOPE, especially for bis (2-chloroethyl) phosphate (BCEP), relative to the reference population. Workshop workers who directly involved in the production of OPEs treated products had higher OPEs exposure. Risk assessment revealed that cancer risk (1.5 × 10^-6-8.5 × 10^-4) for all workers was larger than 1 × 10^-6 when levels of mOPEs in urine from workers were used for estimating OPEs exposure, revealing moderate to high potential cancer risk to workers from OPEs exposure.

CONCLUSION

To our knowledge, this is the first study reporting emissions of OPEs in OPE-treated products manufacturing processes and the potential exposure of the occupationally exposed population. OPEs, especially for TCEP and TCPP, present at elevated levels and pose moderate to high potential health risks to the exposed workers, emphasizing the importance of strengthening occupational exposure prevention in similar industries.

Adipogenic activity of 2-ethylhexyl diphenyl phosphate via peroxisome proliferator-activated receptor γ pathway

Recent studies have shown that exposure to some organophosphates, such as triphenyl phosphate (TPHP) and diphenyl phosphate (DPHP), can affect adipogenesis in preadipocytes. 2-Ethylhexyl diphenyl phosphate (EHDPP), an organophosphate, is frequently detected in various environmental media. However, there is less information about the toxicity effects and the mechanism by which EHDPP affects preadipocytes. In the present study, we investigated whether EHDPP could induce differentiation in 3T3-L1 preadipocytes through the peroxisome proliferator-activated receptor γ (PPARγ) signaling pathway. The fluorescence competitive binding assay and the dual-luciferase reporter gene assay were used to assess the binding affinity and activation of PPARγ, and the results showed that EHDPP can bind to the ligand binding domain of PPARγ (PPARγ-LBD) and activate PPARγ in vitro. Exposure to EHDPP for 10 days extensively induced adipogenesis in 3T3-L1 preadipocytes as assessed by lipid accumulation and gene expression of adipogenic markers of fatty acid binding protein 4 (FABP4), lipoprotein lipase (Lpl), adiponectin (Adip), and fatty acid synthase (Fasn). Furthermore, the preadipocytes differentiation was blocked by the PPARγ-specific antagonist GW9662, indicating that the PPARγ signaling pathway plays an important part in 3T3-L1 cell differentiation induced by EHDPP. Taken together, EHDPP can bind to PPARγ-LBD, activate PPARγ receptor, and induce cell differentiation via the PPARγ signaling pathway in 3T3-L1 preadipocytes.

Occurrence and ecological implications of organophosphate triesters and diester degradation products in wastewater, river water, and tap water

The occurrence and composition profiles of 13 triester organophosphate flame retardants and their three diester metabolites in river water, wastewater, and tap water in China were studied. Most target organophosphate esters (OPEs) were found in water samples, with average concentrations of 787 ng/L for triethyl phosphate (TEP) and 0.1 ng/L for tripropyl phosphate (TPP) in wastewater, 1.48 × 10³ ng/L for TEP and 0.12 ng/L for tripentyl phosphate (TPeP) in river water, and 15.5 ng/L for tris(2-chloroethyl) phosphate (TCEP) and 0.08 ng/L for tritolyl phosphate (TMPP) in tap water. TEP was the most abundant compound among the detected OPEs in all water types. The exposure of zebrafish embryos showed negligible effects of TEP, triphenyl phosphate (TPHP), and diphenyl phosphate (DPHP), while mixed solutions that mimic river water and wastewater composition disturbed the development of embryos and led to the altered transcription of genes relating to the hypothalamic-pituitary-thyroid (HPT) axis. In addition, the binding affinity between OPEs and a thyroid hormone receptor (TRβ) protein was further investigated by molecular docking modeling, which helped to estimate the effects of OPEs on TRβ. This research provides experimental and theoretical evidence for the ecotoxicological effects of OPEs in aquatic environments.

Airborne brominated, chlorinated and organophosphate ester flame retardants inside the buildings of the Indian state of Bihar: Exploration of source and human exposure

Since many household products used by individuals contain flame retardants (FRs), there is more chance that these chemicals may be present in the various exhibit of the indoor environment. Despite being one of the fastest-growing economies worldwide, the contamination level, sources, products, and pathways of FRs in India, is either not known or limited. This inspired us to investigate the level, profile, spatial distribution, and sources of different classes of FRs in the indoor air. For this purpose, 15 brominated, 2 chlorinated, and 8 organophosphate FRs (OPFRs) were investigated in indoor air samples from urban and suburban sites of an Indian state of Bihar. Additionally, inhalation health risk exposure to children and the adult was estimated to predict the risk of these chemicals. Overall, ∑₈OPFRs (median 351 pg/m³) was the most prominent in air, followed by novel brominated FR (∑₆NBFRs) (median 278 pg/m³), polybrominated diphenyl ether (∑₉PBDE) (median 5.05 pg/m³), and dechlorane plus (∑₂DPs) (median 2.52 pg/m³), and accounted for 55%, 44%, 0.8% and 0.4% of ∑FRs, respectively. Generally, ∑₉PBDEs (median 6.29 pg/m³) and ∑₈OPFRs (median 355 pg/m³) were measured high at sub-urban sites, while urban sites had the highest level of ∑₂DPs (median 2.81 pg/m³) and ∑₆NBFRs (median 740 pg/m³). BDE-209 was most abundant among ∑₉PBDEs, while syn-DP dominated in ∑₂DPs. Likewise, DBDPE was most prevalent in ∑₆NBFRs, while TMPP topped among ∑₈OPFRs. The principal component analysis revealed contribution from household items, food packaging and paints, hydraulic fluid, a gasoline additive, and de-bromination of BDE-209 as the primary sources of FRs. The estimated daily inhalation exposure (DIE) indicated a relatively high risk to children than the adult. The DIE of individual FR was several folds lower than their corresponding oral reference dose (RfDs), suggesting minimal risk. However, exposure risk, especially to children, may still need attention because other routes of intake may always be significant in the case of Bihar.

Organophosphate Flame Retardants in Soils of Zhejiang Province, China: Levels, Distribution, Sources, and Exposure Risks

Organophosphate flame retardants (OPFRs) are an emerging class of pollutants. In this study, 62 soil samples were collected from Zhejiang Province China, and screened for 8 typical OPFRs. All compounds were detected in soil at 100% detection frequency, except for triethyl phosphate (TEP) compounds (93.6%). The sum of the eight OPFR concentrations ranged from 9.15 to 132 ng/g dry weight (dw), with mean and median values of 24.9 and 19.0 ng/g dw, respectively. Triphenyl phosphate (TPHP) was identified as the most abundant analog, with a median concentration of 9.94 ng/g dw, followed by tris(2-ethylhexyl)phosphate (TEHP). Significantly higher OPFR concentrations were detected in northern Zhejiang; concentrations decreased sharply from the north to the south. OPFR concentrations in soils from cities or economically developed counties were much higher than those from rural areas. OPFR sources in Zhejiang Province mainly originated from PVC-made products and traffic emissions.  Dermal absorption of OPFRs via soil was the primary pathway for human exposure. Health risks due to exposure to OPFRs through soil ingestion were found to be negligible.

Organophosphate di- and tri-esters in indoor and outdoor dust from China and its implications for human exposure

Organophosphate (OP) esters are emerging environmental contaminants, but little is known about their occurrence in dust. In this study, 19 OP triesters and their 11 diester degradation products were measured in indoor dust and outdoor dust collected from China. ∑OP triester concentrations in indoor dust (median: 2380 ng/g dry weight [dw]) were an order of magnitude higher than those in outdoor dust (446 ng/g dw). The median concentrations of ∑OP diesters in indoor and outdoor dust were 260 and 96.8 ng/g dw, respectively. Dust samples collected from eastern and southern China contained higher concentrations of ∑OP di- and tri-esters than those from the other regions. Dust from the most urbanized areas in China including Beijing, Shanghai, and Guangzhou exhibited the highest concentrations of ∑OP di- (>1000 ng/g dw) and triesters (>4000 ng/g dw). We also found notable concentrations of emerging aryl-OP triesters in dust (3.85-10.6 ng/g dw). Significant correlations existed between the concentrations of bis(2-ethylhexyl) phosphate (BEHP) and tris(2-ethylhexyl) phosphate (TEHP) (rho = 0.672-0.691, p < 0.01), as well as DPHP and triphenyl phosphate (TPHP) (rho = 0.537-0.766, p < 0.01) in dust samples, indicating that OP diesters originated from the degradation of triesters. High molar concentration ratios of DEP to triethyl phosphate (TEP) and DPHP to TPHP/ethylhexyl diphenyl phosphate (EHDPP) suggested that these OP triesters degrade readily. Significant correlations were found between the concentrations of ∑OP di- (R² = 0.390, p < 0.05) and tri-esters (R² = 0.475, p < 0.01) in paired indoor-outdoor dust samples, which suggested that indoor dust was the source of OP esters to the outdoor environment. The estimated daily intake (EDI) of ∑OP diesters through dust ingestion was 0.21 ng/kg bw/d for adults and 2.59 ng/kg bw/d for children. The exposure levels of OP diesters, DEP and DPHP, were comparable to those of their parent triester compounds.

Geographical distributions and human exposure of organophosphate esters in college library dust from Chinese cities

Organophosphate esters (OPEs) in indoor dust were closely related to human health. However, OPE contamination in college library dust remained unknown at present. In this study, OPEs were first investigated in 78 indoor dust samples and 26 field blanks of 26 college libraries from 13 prefecture-level cities across China between October and December 2017. The total OPEs fell in the range of 8706-34872 ng/g, and were dominated by tris(2-chloroisopropyl) phosphate (TCIPP), tris(2-chloroethyl) phosphate (TCEP) and tris(2-butoxyethyl) phosphate (TBOEP). OPEs exhibited geography-specific distributions, with high levels in Beijing, Shanghai and Guangzhou. OPEs significantly correlated with population density and gross domestic product (p < 0.01), indicating the distinct effect of these two indicators on OPE pollution. Analysis of pollution source indicated volatilization and abrasion as main emission pathways of OPEs from OPEs-added products to dust. The daily exposure doses (DEDs) of OPEs via dust ingestion, inhalation and dermal contact were similar for male and female students, ranging from 1.35 to 5.92 ng/kg-bw/day during study time in libraries (25% of day). High DEDs were found in Beijing, shanghai and Guangzhou, indicating high exposure risk of OPEs to college students in large cities. The non-carcinogenic and carcinogenic risks of OPEs to college students were quantitatively evaluated based on the oral reference dose and cancer slope factor of OPEs recently updated by USEPA, and all much lower than the threshold risk values. However, the potential risk may occur if exposure to OPEs is high in other microenvironments over remaining hours of the day.

Organophosphorus flame retardant (tricresyl phosphate) trigger apoptosis in HepG2 cells: Transcriptomic evidence on activation of human cancer pathways

Tricresyl phosphate (TCP) is one of the organophosphorus flame retardants (OPFRs) used as plasticizer in consumer products and mixed as a lubricant in commercial jet engine oil, reportedly induce neurotoxicity and aerodynamic syndrome. No studies have been attempted so far on TCP to induce hepatotoxicity in human cells. This study for the first time confirms the hepatotoxic potential and activation of cancer pathways in TCP treated human hepatocellular cells (HepG2). MTT and NRU data showed 39.3% and 49.85% decline in HepG2 survival when exposed to the highest concentration of TCP (400 μM) for 3 days. Comet assay showed 27.1-fold greater DNA damage in cells treated with TCP (400 μM). Flow cytometric analysis revealed an upsurge in the intracellular reactive oxygen species (ROS) and nitric oxide (NO) production in cells, affirming oxidative stress. TCP (400 μM) exposure resulted in 27% reduction in Rh123 fluorescence, indicating dysfunction of mitochondrial membrane potential (ΔΨm). Cell cycle analysis exhibited 62.53% cells in the subG1 apoptotic phase after TCP (400 μM) treatment, also a massive increase in Ca²⁺ influx validate the on-set of apoptosis in cells. Immunofluorescence of TCP exposed cells showed activation of p53, caspase3, caspase9 reaffirming the involvement of mitochondrial-dependent intrinsic apoptotic signaling. qPCR array of 84 genes unravel the transcriptomic alterations in HepG2 cells after TCP treatment. mRNA transcripts of ATP5A1, GADD45A, IGFBP5, SOD1, STMN1 genes were prominently upregulated providing candid evidence on TCP mediated activation of human cancer pathways to orchestrate the apoptotic death of HepG2 cells, specifying hepatotoxic potential of TCP.

Occurrence, distribution and human exposure to 20 organophosphate esters in air, soil, pine needles, river water, and dust samples collected around an airport in New York state, United States

Organophosphate esters (OPEs) are used in aircraft lubricating oil and hydraulic fluids, and, thus, airplane emissions are thought to be an important source of these chemicals in the environment. In this study, concentrations of 20 OPEs, comprising seven alkyl-OPEs, three chlorinated (Cl)-OPEs, seven aryl-OPEs, and three oligomeric-OPEs, were determined in outdoor air, soil, pine needles, river water, and outdoor dust samples collected around an airport in Albany, New York, in 2018. Elevated ∑OPE concentrations were found in outdoor air, soil, pine needles, outdoor dust, and river water in the ranges of 1320-20,700 pg/m³ (median: 3880), 1.16-73.1 (14.3) ng/g dry weight (dw), 23.2-534 (102) ng/g (dw), 153-2140 (824) ng/g (dw), and 174-24,600 (1250) ng/L, respectively. The total OPE concentrations in air, soil, water, and outdoor dust samples in the study area were dominated by Cl-OPEs, whereas those in pine needles were dominated by aryl-OPEs. The spatial distribution of OPEs in air, soil, and pine needles showed a gradual decreasing trend with increasing distance from the airport. A significant correlation was observed between ∑OPE concentrations in air and soil, and the fugacity ratio showed the flux of OPEs from air to soil. The spatial distribution of OPEs between air and pine needles was similar and highly correlated, suggesting that pine needles are suitable indicators of atmospheric OPE concentrations. In addition to urban activities, aircraft hydraulic/lubricant oils are a major source of OPEs in the vicinity of the airport. The average daily intake of OPEs via air inhalation and outdoor dust ingestion in the vicinity of the airport was up to 1.53 ng/kg bw/day for children and 0.73 ng/kg bw/day for adults.

Occurrence, distribution and health risk assessment of organophosphate esters in outdoor dust in Nanjing, China: Urban vs. rural areas

With increasing use of organophosphate esters (OPEs) largely due to the phasing out of various brominated flame retardants, much more attention has been paid to their occurrence, distribution and potential health risks. In this study, we investigated the occurrence and distribution characteristics associated to their potential health risks of selected 13 OPEs in outdoor dust with a comparison between urban and rural areas in Nanjing, China as well as seasonal variations. Ten out of 13 OPEs showed higher concentrations in urban dust than those in rural dust (p < 0.05). Six OPEs congeners exhibited significantly different concentrations with seasonal variations (p < 0.01) in rural dust. Halogenated OPEs were the dominant group in both urban (median: 56.8%) and rural (median: 45.9%) dust, and tris(2-chloroisopropyl) phosphate (TCPP) was found to be the most abundant OPE in both urban (median: 48.7%) and rural (median:26.4%) dust. Principal component analysis with multiple linear regression (PCA-MLR) and spearman correlations showed the different sources of OPEs in urban and rural dust. The non-carcinogenic (Hazard Index, HI < 1.62 × 10^-5) and carcinogenic risks (CR < 2.28 × 10^-9) of ΣOPEs were much lower than the theoretical threshold of risk, revealing a negligible risk to local residents from the exposure of OPEs in outdoor dust.

Occurrence, distribution, and risk assessment of organophosphate esters in urban street dust in the central province of Henan, China

In this study, nine OPEs were measured in 60 street dust samples collected from the central province of Henan, China. The total concentrations of OPEs (∑₉OPEs) in street dust range from 2.77 to 505 μg/kg (median 59.3 μg/kg). Chlorinated OPEs are dominant in street dust with median concentration of 33.5 μg/kg, followed by aryl OPEs (median 9.05 μg/kg), and alkyl OPEs (median 6.19 μg/kg). No significant correlations are found between ∑₉OPEs and parameters, such as population (p = 0.931), population density (p = 0.602), car ownership (p = 0.618), and gross domestic product (p = 0.863). Principal component analysis (PCA) result reveals that road traffic could be a major source of OPEs in street dust because of their extensive use in various vehicles. The total average (median) and high-level exposure (95th percentile) of OPEs are 1.01 × 10^-2, 7.17 × 10^-2 ng/kg bw/d for adults and 6.03 × 10^-2, 0.43 ng/kg bw/d for children, respectively. Hazard quotient (HQ) values are 5-6 orders of magnitude lower than the acceptable risk level (HQ < 0.1), indicating there is still a low risk to local residents at current levels.

A comprehensive risk assessment of human inhalation exposure to atmospheric halogenated flame retardants and organophosphate esters in an urban zone

Inhalation exposure to flame retardants used as additives to minimize fire risk and plasticizers is ubiquitous in human daily activities, but has not been adequately assessed. To address this research gap, the present study conducted an assessment of human health risk for four age groups through inhalation exposure to size fractionated particle-bound and gaseous halogenated flame retardants (polybrominated diphenyl ethers (PBDEs) and alternative halogenated flame retardants (AHFRs)) and organophosphate esters (OPEs) at indoor and outdoor environments (school, office, and residence) in three districts of a megacity (Guangzhou, China). Results demonstrated that OPEs were the dominant components among all targets. Indoor daily intakes of PBDEs and OPEs were 13-16 times greater than outdoor levels for all age groups. Gaseous OPEs contributed significantly greater than particle-bound compounds to daily intakes of all target compounds. Based on the different life scenarios, hazard quotient (HQ) and incremental life cancer risk (ILCR) from adults exposure to PBDEs and OPEs in indoor and outdoor settings were the greatest, followed by adolescents, children, and seniors. The estimated HQ and ILCR for all age groups both indoors and outdoors were lower than the safe level (HQ = 1 and ILCR = 10^-6), indicating that the potential health risk for local residents in Guangzhou via inhalation exposure to atmospheric halogenated flame retardants and OPEs was low.

Data relating to fate and transport of organophosphate ester flame retardants in indoor air and dust from Nepal

The ubiquitous occurrence of organophosphate ester flame retardants (OPFRs) may pose a threat to human health. Most of the OPFRs are suspected to be carcinogenic, neurotoxic and can cause fertility and reproductive effects (World Health Organization, 2000) and (Van der Veen and De Boer, 2012). Although a number of researches have detailed high level of organophosphate ester flame retardant worldwide, unfortunately Nepal has never been part of any global/regional monitoring campaign. This data article presents the concentration of eight different compounds of organophosphate ester flame retardants (OPFRs) measured in indoor air and house dust. Thirty four indoor air and 28 house dust samples were collected from four major cities (Kathmandu, Pokhara, Birgunj, and Biratnagar) of Nepal to investigate the contamination level and distribution pattern of OPFR. The median concentration and relative contribution of individual OPFR has been also discussed (Yadav et al., 2017).

Semi-volatile organic compounds in infant homes: Levels, influence factors, partitioning, and implications for human exposure

While infants are developing, they are easily affected by toxic chemicals existing in their environments, such as semi-volatile organic compounds (SVOCs): phthalates, polycyclic aromatic hydrocarbons (PAHs), polybrominated diphenyl ethers (PBDEs), and organophosphate esters (OPEs). However, the specific living environment of infants, including increased plastic products and foam floor mats, may increase the presence of these chemicals. In this study, 68 air, dust, and window film samples were collected from homes, with 3- to 6-month-old infant occupants, to analyze phthalates, PAHs, PBDEs, and OPEs. High detection rates and concentrations suggest that these SVOCs are widespread in infant environments and are associated with cooking methods, smoking habits, the period of time after decoration, and room floors. The partitioning behavior of SVOCs indicates that the logarithms of the dust/gas-phase air partition coefficient (logK_D) and the window film/gas-phase air partition coefficient (logK_F) in homes are not at an equilibrium state when the logarithm of the octanol/air partition coefficient (logK_OA) is less than 8 or greater than 11. Considering the 3 exposure routes, ingestion and dermal absorption have become the main routes of infant exposure to phthalates and OPEs, and ingestion and inhalation have become the dominant routes of exposure to PAHs and PBDEs. The total carcinogenic risk of SVOCs, which have carcinogenic toxicities, via ingestion and dermal absorption for infants in homes exceeds the acceptable value, suggesting that the current levels of these SVOCs in homes might pose a risk to infant health.

Examining the role of total organic carbon and black carbon in the fate of legacy persistent organic pollutants (POPs) in indoor dust from Nepal: Implication on human health

Despite the fact that the consumption and import of legacy persistent organic pollutants (POPs) have been stopped in Nepal since 2001, they are still of worry for human prosperity and the environment because of their persistence behavior and constant release from sources that are presently being used. The essential objective of this study was to assess the concentration and spatial distribution of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) in residential dust from Nepal keeping in mind the end goal to evaluate the importance of total organic carbon (TOC) and black carbon (BC) in the fate of legacy POPs. Additionally, health risk exposure via dust ingestion and dermal absorption was estimated to evaluate the significance of dust media for human exposure. Results demonstrated that ∑OCPs in dust was 37 times greater than ∑PCBs. DDT was mostly dominated in the dust, and contributed 90% of the ∑OCPs, while hexa-CBs predominated among PCBs and represented 34% of ∑PCBs. Birgunj and Biratnagar had a relatively higher level of ∑OCPs and ∑PCBs than those of Kathmandu and Pokhara. TOC and BC showed a poor connection with OCPs, recommending little or no role. However, PCB in the dust, especially low congeners was strongly linked with TOC but not BC indicating the significant role of TOC. The daily risk exposure estimation indicated dermal absorption through dust as the principal means of OCPs/PCBs intake to both adult and children population. These estimated exposures were 2-4 orders of magnitude inferior to their corresponding reference dose showing insignificant risk.

A nationwide survey of 19 organophosphate esters in soils from China: Spatial distribution and hazard assessment

Organophosphate esters (OPEs) are ubiquitous in the environment, but little is known about their distribution in soils. In this study, we measured 19 OPEs in soil samples collected nationwide in China for the first time. Concentrations of 19 OPEs (∑OPEs) in soils ranged from 4.50 to 430 ng/g dry weight (dw), with a median value of 36.6 ng/g dw. ∑OPE concentrations in soils were significantly higher in Northeastern (90.6, 19.1-180 ng/g dw; median, range) and Eastern/Southern China (57.4, 7.23-430 ng/g dw), areas with high population density and economic development, than those in Central (35.8, 4.80-417 ng/g dw) and Western China (29.7, 4.50-228 ng/g dw). High concentrations of ∑OPEs were found in soils collected from sites located in the most urbanized areas of China including Beijing (126 ng/g dw), Shanghai (388 ng/g dw), and Guangzhou (430 ng/g dw). Chlorinated (Cl-) OPEs were the predominant compounds, accounting for over 74.0% of ∑OPE concentrations in soils from China. In soil samples from Northeastern and Eastern/Southern China, Cl-OPEs accounted for 84.3% and 92.1% of ∑OPE concentrations, respectively. Cresyl diphenyl phosphate (CDPP) and isodecyl diphenyl phosphate (IDDP), which have been less studied thus far, were also found at measurable concentrations (0.15-0.40 ng/g dw) in soils. The Spearman's rank correlations among major aryl-OPEs in soils were significant (Rho = 0.582-0.747, p < 0.01), which suggested similar sources of environmental release of these compounds. Total organic carbon (TOC) content was not correlated with the concentrations of ∑OPE in soils (Rho = 0.036, p > 0.05). A hazard assessment for ten OPEs in soils suggested a notable risk from tris(2-ethylhexyl) phosphate (TEHP) and trimethylphenyl phosphate (TMPP). Further studies are needed to elucidate the fate of TMPP in soils.

Temporal variations of PM2.5-bound organophosphate flame retardants in different microenvironments in Beijing, China, and implications for human exposure

In the present study, the temporal distribution of PM_2.5-bound organophosphate flame retardants (OPFRs) was comprehensively investigated in various indoor environments as well as outdoor air in Beijing, China over a one-year period. The mean concentrations of Σ₉OPFRs were 22.7 ng m^-3 and 1.40 ng m^-3 in paired indoor and outdoor PM_2.5, respectively. The concentrations of tri-n-butyl phosphate (TNBP), tris (2-chloroethyl) phosphate (TCEP) and tris (2-chloroisopropyl) phosphate (TCIPP) in indoor PM_2.5 were significantly correlated with those in outdoor PM_2.5. For different indoor microenvironments, mean concentrations of Σ₉OPFRs were in the order of office (29.0 ± 11.7 ng m^-3) > home (24.0 ± 9.4 ng m^-3) > dormitory (19.4 ± 4.9 ng m^-3) > activity room (14.4 ± 3.1 ng m^-3). TCIPP was the most abundant compound in the indoor PM_2.5, followed by TCEP. Significantly higher concentrations of OPFRs were observed in indoor environments with more furnishing, electronics or other materials (p < 0.05). Moreover, lower levels of OPFRs in indoor air were observed at well-ventilated (with higher air exchange rate) indoor sampling sites. Concentrations of Σ₉OPFRs in the activity room, dormitory, homes and outdoor sites generally increased in summer and heating seasons (November 2016 to February 2017). Significant correlations (p < 0.05) were observed between temperatures and mass concentrations of OPFRs with higher vapor pressures, i.e. TNBP, TCEP and TCIPP in all indoor and outdoor samples. Seasonal differences in human exposure were observed and the highest daily exposure dose occurred in summer. Toddlers may suffer the highest exposure risk of PM_2.5-bound OPFRs via inhalation among all age groups. This is one of the very few studies that have revealed the seasonal variation and human exposure of PM_2.5-bound OPFRs in different microenvironments, which shed light on emission sources and fate of OPFRs and potential human exposure pathway.

Impacts of texture properties and airborne particles on accumulation of tobacco-derived chemicals in fabrics

Vapor-phase constituents of tobacco smoke are known to accumulate on clothing surfaces; however, the significance of texture properties, such as specific surface area, porosity, and surface roughness, and airborne particles to the sorption capacity of fabrics has not been adequately addressed. In the present study, cotton (t-shirt) and polyester (pajama and lab coat) fabrics were exposed to cigarette smoke containing gaseous and particulate tobacco-derived compounds (e.g., N-nitrosamines). Fabric-air distribution coefficients and particle deposition fluxes were then determined to evaluate the accumulation of the target analytes. Appreciable amounts of N'-nitrosoanabasine (NAB) and 4'-(nitrosomethylamino)-1-(3-pyridyl)-1-butanone (NNK) were detected in all three fabric types although particle-bound NAB and NNK were found only in cigarette smoke. In addition, the root mean square surface roughness heights for three types of clothes were within the same order of magnitude. As such, the deposition fluxes of particle-bound N'-nitrosonornicotine (NNN) and NNK to fabric surface may have contributed to 6-20% and 56-100% of total NNN and NNK in fabrics, respectively, estimated based on the assumed deposition velocity of 0.65 m h^-1. Apparently, the sorption capacity of fabrics can be greatly influenced by particle-bound compounds on clothing surfaces, resulting in either over- or under-estimation of fabric-air distribution/partitioning coefficients.

Organophosphate Esters in Road Dust from a Suburban Area of Chongqing, China: Characterization of Particle Size Distribution and Human Exposure

Four types of road dust, including main road, industrial road, campus road, and campus walking street dust, were analyzed in a suburban area of Chongqing, western China. The organophosphate esters (OPEs) concentrations varied from 3.69 to 1600 ng/g dry weight, with a median of 292, 476, 203, and 48.8 ng/g dw in main road, industrial road, campus road, and campus walking street dust, respectively. The industrial sources should be responsible for the elevated OPEs concentrations in industrial road dust, while the vehicle emissions may play a role in the OPEs distribution in main road dust. Semblable OPEs composition patterns were observed among different types of road dust; tributyl phosphate predominated followed by tris(methylphenyl) phosphate. Significantly positive correlations were obtained between industrial road dust and campus road dust and main road dust, respectively, and statistical correlations also were found between main road dust and other road dust. An increasing trend of OPEs was displayed with the descending particle size in industrial road dust, whereas highest values were at F3 (90-150 μm) (340 ng/g dw) and F5 (< 75 μm) (305 ng/g dw), with a peak value at F3 in main road dust. This result may suggest that OPEs are prone to accumulate in finer particles. The estimated daily intake values for toddlers were approximately two times greater than those for adults in each region, implying that toddlers may be more vulnerable to OPEs intake via road dust.

Assessing the threats of organophosphate esters (flame retardants and plasticizers) to drinking water safety based on USEPA oral reference dose (RfD) and oral cancer slope factor (SFO)

As one group of emerging pollutants, the threat of organophosphate esters (flame retardants and plasticizers, OPEs) to drinking water safety is not well recognized. Now, the oral reference dose (RfD) and oral cancer slope factor (SFO) of OPEs have been updated by USPEA, therefore the threat of OPEs to drinking water safety could be assessed. In this study, occurrence, health risk and key impact factor of OPEs in drinking water of China were analyzed covering 79 cities, whose population and gross domestic product (GDP) accounted for 28.8% and 44.1% of them in China, respectively. Total concentration of 14 common OPEs in drinking water was 13.42-265.48 ng/L. The exposure level of OPEs via ingestion of drinking water was much lower than that of food ingestion but was comparable with dust ingestion, inhalation and dermal absorption. A health assessment for OPEs via ingestion of drinking water suggested that the potential cancer risk occurred (>1.00E-6) but no obvious non-carcinogenic effects occurred (<1). Tris-(2,3-dibromopropyl) phosphate (TDBPP) contributed to about 72.4% of carcinogenic risk, which should be treated as "prior monitoring OPEs" in further studies. The occurrence and distribution of OPEs in drinking water of China have a good corresponding relationship with the Aihui-Tengchong Line, and drinking water treatment technology (DWTT) was found to be a key factor. Total OPEs, halogeno-OPEs and alkyl-OPEs in drinking water from advanced DWTT cities were much lower than those of conventional DWTT cities. Compared with conventional DWTT, advanced DWTT could reduce about 65.6% and 36.5% of carcinogenic risk and non-carcinogenic risk of OPEs, respectively. Considering the annual growth of OPEs consumption in China and world, further studies regarding the environmental threat of OPEs are required.

Organophosphate flame retardants emitted from thermal treatment and open burning of e-waste

Organophosphate flame retardants (OPFRs) have been increasingly produced and consumed since the gradual phase-out of polybrominated diphenyl ethers. Primitive recycling of e-waste can be a significant input source of OPFRs to the environment. Thermal treatment and open burning of typical e-wastes were conducted in a closed chamber to examine the emissions and the size distribution patterns of particle-bound OPFRs from these processes. The sum emission factors of OPFRs were 3.70 × 10⁴-3.65 × 10⁵ ng g^-1 by thermal treatment and 5.22 × 10³-9.27 × 10⁴ ng g^-1 by open burning. The output-input mass ratios of OPFRs for plastic casings were 0.030-116 and 0.012-7.1 by thermal treatment and open burning, respectively, and were 0.11-40 and 0.0014-6.7 for printed circuit boards. The size distribution patterns of OPFRs were characterized by one unimodal peak (0.56-1.0 μm) for thermal treatment and bimodal peaks (0.56-1.0 or 1.0-1.8 and 10-18 μm) for open burning. Particle-bound OPFRs appeared to form in affiliation with particles rather than by adsorption or deposition from the gaseous phase to particulate organic matter. With increasing amounts of OPFRs used in a variety of consumer products, the emissions of OPFRs to the environment are expected to increase continuously in the future.

OPFRs and BFRs induced A549 cell apoptosis by caspase-dependent mitochondrial pathway

Organophosphate flame retardants (OPFRs) and brominated flame retardants (BFRs) are frequently detected in indoor environment at high levels, posing health risks to humans. However, the potential cytotoxicity mediated by OPFRs and BFRs in relevant human cell models is limited. In current study, non-small cell lung cancer A549 cell was employed to investigate toxicity mechanisms of typical OPFRs (i.e., tris (2-chloroethyl) phosphate (TCEP), tris-(2-chloropropyl) phosphate (TCPP), tricresy phosphate (TCP), triphenyl phosphate (TPHP) and BFRs (i.e., 2,2',4,4'-tetrabromodiphenyl ether (BDE-47), 3,3', 5,5'-tetrabromobisphenol A (TBBPA)). It was found that BDE-47 exhibited the strongest cytotoxicity, followed by TBBPA, TPHP, TCP, TCPP and TCEP. OPFRs and BFRs could cause the reduction of cell viability of A549 cell in both dose- and time-dependent manner after exposure for 24 and 48 h. Simultaneously, excessive generation of reactive oxygen species (ROS), mitochondrial membrane potential (MMP) dysfunction, cell apoptosis and overload of intracellular free Ca²⁺ demonstrated that cytotoxicity induced by OPFRs and BFRs were mediated by oxidative stress. Of note, the survival rate of cell significantly increased when pretreated with Ac-DEVD-CHO, suggesting that caspase-3 dependent mitochondrial pathway may have played a primary role in the process of A549 cell apoptosis.

A nationwide survey of 31 organophosphate esters in sewage sludge from the United States

Organophosphate esters (OPEs) are used as flame retardants and plasticizers in a wide range of consumer products. Nevertheless, studies on the occurrence and inventory of OPEs in sewage sludge are limited. In this study, 20 OP triesters and 11 diesters were measured in 75 archived sewage sludge samples collected from 67 wastewater treatment plants (WWTPs) across the United States (US). The median concentrations of ∑20OP-triesters and ∑11OP-diesters in sludge were 1290 and 78.4 ng/g dry weight (dw), respectively. Sludge samples originating from the Western and Northeastern US contained higher concentrations of OP triesters than did those from the Midwestern and Southern US. Sludge samples from WWTPs with larger treatment capacity (>38 million liters per day) contained higher concentrations of OP diesters (p < 0.05). OP diesters in sludge originated from two sources, triester degradation and direct inputs. Land application of sludge to US soils was estimated to result in annual mass inputs of 12,400-14,900 kg/year of OP triesters and 663-796 kg/year of OP diesters. A hazard assessment was performed for 14 OPEs found in sludge, which suggested a low level of risk at the current land application practices of sludge.

Grain size distribution and exposure evaluation of organophosphorus and brominated flame retardants in indoor and outdoor dust and PM10 from Chengdu, China

To investigate overall pollution and potential risk of 32 targets (11 PBDEs, 8 NBFRs, and 13 OPFRs) in indoor and outdoor environments, dust and PM10 samples were sampled from non-occupational and occupational zones in Chengdu, China. ∑Cl-OPFRs, BDE-209, and DBDPE were the dominant constitutes in both the non-occupational and occupational dust. Regarding the PM10, no significant differences were found between the kitchen and the living room for studied OPFRs except TDCIPP, and TCEP, TCPP, TEHP, and TCP displayed significant correlation among the kitchen, the living room and personal samples. Profiles of the OPFRs in the PM10 from occupational areas presented great variation and ranked as: ∑Aryl-OPFRs < ∑Alkyl-OPFRs < ∑Cl-OPFRs. The estimated daily intakes (EDIs) of the investigated FRs via dust suggested dust ingestion and inhalation were the main exposure route to FRs, and the total of EDIs were at least one order of magnitude lower than reference data, indicating a low risk for the general public in Chengdu. However, with increasing usage of FRs in daily goods, a long-term monitoring should be conducted.

Presence and human exposure assessment of organophosphate flame retardants (OPEs) in indoor dust and air in Beijing, China

In this study, levels of 14 organophosphate flame retardants (OPEs) were measured in 101 indoor dust samples collected from dormitories, residential homes, and offices in Beijing, China. In addition, paired air samples were also analyzed to evaluate any correlation between OPE levels in air and that in corresponding dust samples. The Σ₁₄OPEs levels substantially varied between individual samples. Thereinto, significantly higher OPE levels were found in dust samples from office (mean value: 14 μg g^-1), comparing to that in dust samples from residential homes (mean value: 5.9 μg g^-1) and dormitories (mean value: 6.9 μg g^-1). Congener profiles of OPEs in dust samples from different microenvironments indicated that tris (2-chloroethyl) phosphate (TCEP) was the dominant OPE in the office samples, followed by tris (2-chloroisopropyl) phosphate (TCPP). In contrast, TCPP was the dominant OPE in the residential home and dormitory samples, followed by TCEP. The mean concentration (range) of Σ₁₄OPEs in the 15 air samples was 5.2 (1.0-20) ng m^-3, and TCPP was the dominated congener in these samples. The concentration of TCEP and TCPP in air was positively correlated with that in corresponding indoor dust, and OPEs with highly saturated vapor pressures have higher fractions in the air than that in the dust. The estimated daily intakes through dust ingestion, dermal absorption, and inhalation indicated that the exposure to OPEs in indoor environments do not result in significant health risk for the general population in Beijing.

Spatial distribution, source analysis, and health risk assessment of heavy metals contamination in house dust and surface soil from four major cities of Nepal

Raising population, deteriorating environmental conditions and limiting natural resources to handle the key environmental health problems have critically affected human health and the environment. Policy makers and planners in Nepal are more concerned today than at any other time in the past about the deterioration of the environmental condition. Therefore, understanding the connection between pollution and human wellbeing is fundamental endeavors to control pollution exposures and secure human wellbeing. This ability is especially critical for countries like Nepal where the issues of environmental pollution have customarily taken a second place to request for economic development. In this study, spatial distribution and sources of 12 heavy metals (HMs) were investigated in surface soils (n = 24) and house dust (n = 24) from four major urban areas of Nepal in order to mark the pollution level. Additionally, a health risk was estimated to establish the link between HMs pollution and human health. Results showed that the median concentration of Ag, Cd, Co, Cr, Cu, Ni, Pb, Sb, Mn and Zn in soil and dust were 2-13 times greater than the background value. The As, Zn, Cu, Cd, and Pb showed a relatively higher spatial variability in soil and dust. Zn was the most abundant metal measured in dust and soil and accounted for 59% and 55% of ∑₇HMs, respectively. The HMs in soil and dust were poorly correlated with total organic carbon (TOC) and black carbon (BC), suggesting little or no influence on HMs contamination. Source analysis study indicated the distribution of Cr, Ni, Sb, Ag, Pb, Cu, and Zn in soil and dust are mainly affected by anthropogenic sources, particularly traffic emissions, industrial source, and domestic households materials, while Co, Fe, As, Mn and Cd were from natural sources. The estimated carcinogenic risk (CR) of HMs in soil and dust exceeded the acceptable level of human exposure, recommending significant CR to the local population.

Organophosphate esters in the water, sediments, surface soils, and tree bark surrounding a manufacturing plant in north China

Emission from manufacturing facilities to the surrounding environment is one of the important input source of pollutants. However, no information on the levels of organophosphate esters (OPEs) contamination in the environmental media around the manufacturing facility is available to date. In this study, samples from various environmental media, including sediments, water, surface soils, and tree bark, were obtained near an OPE manufacturing plant in Hengshui, Hebei Province, North China. The three main congeners, detected were tris(2-chloroethyl) phosphate (TCEP), tris(2-chloroisopropyl) phosphate (TCIPP), and triphenyl phosphate (TPHP), with the summed OPE concentrations (∑OPEs) ranging from 340 to 270,000 μg kg^-1 dry weight (d.w.), 7100 to 33,000 ng L^-1, not detected (N.D.) to 14,000 ng kg^-1 d.w., and 5300 to 19,000 ng g^-1 lipid weight in the sediments, water, soils, and tree bark, respectively. These findings suggest that point sources of OPEs could have widespread effects on its surrounding environments. Sediment and water concentrations of TCEP and TCIPP measured in this study were among the highest concentrations yet reported in the world. Meanwhile, the concentration ranges of TCEP and TCIPP in surface soils were significantly lower than those in the sediment and water, and among the lowest concentrations yet reported in soil data worldwide. This suggests that the manufacturing facility influenced the OPE distribution in different environmental media in different ways. Furthermore, TCEP and TCIPP might have been transported within the water stream from roots into the aboveground plants and then accumulated in tree barks.

Distributions of organophosphate flame retardants (OPFRs) in three dust size fractions from homes and building material markets

The distributions of organophosphate flame retardants (OPFRs) in various size fractions of indoor dust samples from homes (H; n = 18) and building material markets (B; n = 7) in the Rhine/Main region of Germany were investigated. Three particle size fractions (F1: 150-200 μm, F2: 63-150 μm, and F3: <63 μm) and bulk dust (BD) subsamples (<200 μm) of each sample were analyzed for 10 OPFRs. On average, the total OPFR concentrations (∑₁₀OPFR) in bulk dust and all three size fractions from building material markets were 133, 153, 196, and 88.0 μg/g in subsamples B-BD, B-F1, B-F2, and B-F3. These concentrations were at least five times higher than those in bulk dust and all three size fractions from homes, with values of 19.3, 17.2, 19.5, and 18.7 μg/g for subsamples H-BD, H-F1, H-F2, and H-F3, respectively. Tris(2-chloroisopropyl)phosphate (TCIPP) was the dominant congener in dust from building material markets, contributing over 91% to the ∑₁₀OPFR of B-BD and all particle size fractions. Meanwhile, both tris(2-butoxyethyl)phosphate (TBOEP) and TCIPP were abundant in dust from homes, respectively contributing 28%-41% and 31%-43% to the ∑₁₀OPFR of H-BD and all particle size fractions. Most of the OPFR concentrations showed no consistent trend with particle size. However, TCIPP was more likely to be enriched in F2. Microscopic examination indicated that TCIPP in indoor dust mainly originated from abraded fragments of commercial products. In contrast, TBOEP accumulated in F3, related to direct transfer of floor-care products to fine dust particles. The concentrations of OPFRs were not significantly correlated with total organic carbon contents in any particle size fraction. However, evaluation of their mass contributions showed that more than 85% of OPFRs accumulated in particles smaller than 150 μm, indicating that this particle size fraction is most suitable for monitoring of OPFRs.

Measurement of legacy and emerging flame retardants in indoor dust from a rural village (Kopawa) in Nepal: Implication for source apportionment and health risk assessment

Under the Stockholm Convention, signatory countries are obliged to direct source inventories, find current sources, and provide ecological monitoring evidence to guarantee that the encompassing levels of persistent organic pollutants (POPs) are declining. However, such monitoring of different types of POPs are to a great degree constrained in most developing countries including Nepal and are primarily confined to suspected source area/ densely populated regions. In this study, 9 polybrominated diphenyl ethers (PBDEs), 2 dechlorane plus (DPs), 6 novel brominated flame retardants (NBFRs) and 8 organophosphate ester flame retardants (OPFRs) were investigated in indoor dust from a rural area (Kopawa) in Nepal in order to evaluate their occurrence/level, profile, spatial distribution and their sources. Additionally, health risk exposure was estimated to anticipate the possible health risk to the local population. The results showed that OPFRs was the most abundant FR measured in the dust. The concentration of ∑₈OPFRs was about 2, 3 and 4 orders of magnitude higher than the ∑₆NBFRs, ∑₉PBDEs, and ∑₂DPs, respectively. Tris (methylphenyl) phosphate (TMPP) and Tris (2-ethylhexyl) phosphate (TEHP) were the most abundant OPFRs analyzed in the dust; while decabromodiphenyl ethane (DBDPE) exceeded among NBFRs. Likewise, 2,2',3,3',4,4',5,5',6,6'-decabromodiphenylether (BDE-209) was the most identified chemical among PBDEs. The total organic carbon (TOC) content in dust was significantly and positively connected with octa-BDEs (Rho = 0.615, p < 0.01), BTBPE (Rho = 0.733, p < 0.01), TPHP (Rho = 0.621, p < 0.01), TEHP (Rho = 0.560, p < 0.01) and TMPPs (Rho = 0.550, p < 0.01), while black carbon (BC) was either weakly related or not related, suggesting little or no impact of BC in the distribution of FRs. Principal component analysis indicated the contribution from commercial penta-, octa- and deca-BDEs formulation, the adhesive substance, food packaging and paints, and degradation of BDE-209 as the essential sources of FRs. Health risk exposure estimates showed that dermal absorption via dust as the primary route of FRs intake. The estimated daily exposure of PBDEs, NBFRs and OPFRs were 2-10 orders of magnitude lower than their corresponding reference dose (RfD), suggesting insignificant risk. However, other routes such as inhalation and dietary intake might still be significant in the case of Kopawa which should be tested in future.

Occurrence of organic phosphates in particulate matter of the vehicle exhausts and outdoor environment - A case study

The occurrence and concentrations of a wide range of organic phosphates (OPEs) in vehicle's exhaust (VPM), ambient air particulate matter (APM), and soil of various urban environments were researched. VPM comes from passenger cars, commercial vehicles, marine and bus engines emitted in New European Driving Cycle tests whereas APM was sampled in several sites of the Upper Silesia region (Poland). APM and VPM collected on filters and soil from the same locations as APM sampling sites were extracted with dichloromethane and extracts analyzed by gas chromatography-mass spectrometry. The OPEs found include aryl phosphates such as triphenyl phosphate (TPhP) and tricresyl phosphate (TCP), alkyl phosphates - triethyl phosphate (TEP), tripropyl phosphate (TPP), tributyl phosphate (TBP) and tri(butoxyethyl)phosphate (TBEP), and alkylchlorinated phosphates including tris-(2-chloroisopropyl) phosphate (TCiPP) and tris(2-chloroethyl) phosphate (TCEP). Occurrence and concentrations of these compounds in the PM investigated are highly variable. It was found that total concentrations in APM are directly related to traffic density in particular sites of the urban environment and a style of a vehicle driving. The highest emission of OPEs was found at a crossroad and city center sites where traffic is the densest and vehicles stops and starts are frequent. Village and residential areas were less exposed to OPEs emission. Since OPEs concentrations show exponential correlations to each other also human exposure to these compounds increases exponentially with increasing traffic density. High TEP and TBP level is tentatively proposed as an indicator of emission from petrol-fueled cars. Concentrations of OPEs in some soil are related to their emission to the air and resistance to degradation of a particular compound since only the most resistant TCiPP and TPhP were identified in soil extracts.

Are cell phones an indicator of personal exposure to organophosphate flame retardants and plasticizers?

BACKGROUND

Exposure to organophosphate ester (OPE) flame retardants and plasticizers is widespread and is of concern due to their toxicity.

OBJECTIVES

To investigate relationships between and within OPE concentrations in air, dust, hands, electronic product wipes and urinary metabolites with the goal of identifying product sources and exposure pathways.

METHODS

Women in Toronto and Ottawa, Canada, provided a urine sample, two sets of hand wipes, access to their homes for air and dust sampling, and completed a questionnaire. OPE concentrations were obtained for air and floor dust in the bedroom (n = 51) and most used room (n = 26), hand wipes (n = 204), and surface wipes of handheld (n = 74) and non-handheld electronic devices (n = 125). All air, dust and wipe samples were analyzed for 23 OPE compounds; urine samples (n = 44) were analyzed for 8 OPE metabolites.

RESULTS

Five-8 OPEs were detected in >80% of samples depending on the sample type. OPE median concentrations in hand wipes taken 3 weeks apart were not significantly different. Palms had higher concentrations than the back of hands; both were significantly correlated. Concentrations of 9 OPEs were significantly higher in surface wipes of handheld than non-handheld electronic devices. Six OPEs in hand wipes were significantly correlated with cell phone wipes, with two to four OPEs significantly correlated with tablet, laptop and television wipes. Multiple regression models using hand wipes, cell phone wipes and dust explained 8-33% of the variation in creatinine-adjusted urinary metabolites; air concentrations did not have explanatory power. OPEs in cell phone wipes explained the greatest variation in urinary metabolites.

CONCLUSIONS

Handheld electronic devices, notably cell phones, may either be sources or indicators of OPE exposure through hand-to-mouth and/or dermal uptake.

Concentrations and Dietary Exposure to Organophosphate Esters in Foodstuffs from Albany, New York, United States

Organophosphate esters (OPEs) are ubiquitous contaminants in the environment, but little is known about their occurrence in foodstuffs, an important source of human exposure. In this study, 15 OPEs were measured in foodstuffs and food-packing materials collected from local markets in Albany, New York, United States, for the first time. Among the foodstuffs analyzed, median concentrations of ∑OPEs (sum of 15 OPEs) in meat (6.76 ng/g wet weight; ww) and fish/seafood (7.11 ng/g ww) were higher than those in other food categories. ∑OPEs were found in food packaging at a median concentration of 132 ng/g. The estimated daily dietary intakes (EDIs) of OPE were of 37.9, 135, 56.6, 32.2, and 25.1 ng/kg body weight (bw)/day for infants, toddlers, children, teenagers, and adults, respectively. Meat was a major source (47%) of dietary OPEs exposure in adults, whereas dairy products accounted for 52% of OPE exposures in toddlers.

Organophosphorus esters (OPEs) in PM2.5 in urban and e-waste recycling regions in southern China: concentrations, sources, and emissions

Organophosphate esters (OPEs) are novel ubiquitous contaminants that are attracting growing concern, but their emissions into the environment are still poorly understood. In this study, 12 OPEs were measured in fine particulate matter (PM_2.5) at 20 industrial sites in an urban region and four e-waste recycling facilities in a rural region in southern China. There was no significant difference in the concentrations of ∑OPEs between the urban region (519-62,747 pg/m³, median = 2854 pg/m³) and the rural e-waste region (775-13,823 pg/m³, 3321 pg/m³). High OPE concentrations in urban PM_2.5 were generally associated with the electrical, electronic, plastic, and chemical industries. There were no significant correlations between most OPEs in these two regions, suggesting different emission mechanisms. The average emissions of ∑OPEs estimated using a simplified dispersion model were 73.0 kg/yr from the urban industrial point sources and 33.2 kg/yr from the e-waste recycling facilities. The estimated emission inventory from industrial activities in the whole city (3228-4452 kg/yr) was approximately 30-fold higher than that from the e-waste recycling (133 kg/yr) facilities because urban region has a much larger industrial scale. To the best of our knowledge, this is the first effort to model the emissions of OPEs from industrial and e-waste recycling activities to the atmosphere.

Occurrences, sources, and transport of hydrophobic organic contaminants in the waters of Fildes Peninsula, Antarctica

As a pristine continent, Antarctica provides a good opportunity to study the spatial transport and temporal accumulation of environmental contaminants and the impacts of anthropogenic activities, both of which have given rise to ongoing public concern. In this research, an approach of coupling aquatic time-integrated passive sampling with chemical analysis and bioassays was used to assess pollution by hydrophobic organic contaminants in Antarctic waters. Passive samplers were deployed in waters of Fildes Peninsula, Antarctica, and their extracts were used for chemical analyses of sixty-six hydrophobic organic contaminants belonging to five groups [organophosphorus flame retardants (PFRs), phthalic acid esters (PAEs), polycyclic aromatic hydrocarbons (PAHs), organochlorine pesticides (OCPs), and polychlorinated biphenyls (PCBs)] and in vitro bioassays for endocrine disruption and genotoxicity. In total, twenty pollutants (six PFRs, one PAE, two PAHs, six OCPs, and five PCBs) were quantified, and six PFRs had concentrations that ranged from ND (not detected) to 44.37 ng L^-1 in Antarctic waters. The concentrations detected in the waters were generally low and insufficient to have significant in vitro endocrine disruption potential or genotoxicity. The source and transport pathways of PFRs and PAE in Fildes Peninsula were studied, and multiple local sources (wastewater, air traffic, research stations, and animal feces) for different PFRs were proposed. A spatial and temporal analysis showed slight changes in the exposure of OCPs and PCBs in Antarctic waters. Furthermore, a comparison among a variety of Antarctic water sampling cases revealed that passive sampling can be a tool for aquatic time-integrated investigations in polar regions.

Occurrence, distribution and risk assessment of organophosphate esters in surface water and sediment from a shallow freshwater Lake, China

Organophosphate esters (OPEs) are ubiquitous in the environment and pose a potential threat to ecosystem and human health. This study investigated the concentrations, distributions and risk of 12 OPEs in surface water and sediment from Luoma Lake, Fangting River and Yi River. Solid-phase extraction (SPE) method were used to extract OPEs from water samples, ultrasonic process and SPE method were used to extract OPEs from sediment samples, and the extracts were finally analyzed using the HPLC-MS/MS. The results revealed that the median and maximum concentrations of ΣOPEs were 73.9 and 1066 ng/L in surface water, and were 28.7 and 35.9 ng/g in sediment, respectively. Tris(2-chloroethyl) phosphate (TCEP) and trimethyl phosphate (TMP) were the most abundant OPEs in the surface water with median concentrations of 24.3 and 16.4 ng/L in Luoma Lake, respectively. Triethyl phosphate (TEP) was the most abundant OPE in the sediment with a median concentrations of 28.9 ng/g. However, tricresyl phosphate (TCrP) and ethylhexyl diphenyl phosphate (EHDPP) predominantly contributed to the ecological risk with respective median risk quotients 0.07 and 0.01 for surface water in Luoma Lake. TEP and TCrP were the most significant contributors to the ecological risk with respective median risk quotients of 6.4 × 10^-4 and 5.6 × 10^-4 for sediment. It was also found that inflowing Fangting River could be the major pollution source to Luoma Lake. The no-cancer and carcinogenic risks of OPEs were lower than the theoretical threshold of risk. The study found that the ecological and human health risks due to the exposure to OPEs were currently acceptable. In other words, the Luoma Lake was relatively safer to use as a drinking water source in urban areas in the context of OPEs pollution.

Exposure to brominated and organophosphate ester flame retardants in U.S. childcare environments: Effect of removal of flame-retarded nap mats on indoor levels

We assessed exposure to 39 brominated and 16 organophosphate ester flame retardants (FRs) from both dust and indoor air at seven childcare centres in Seattle, USA, and investigated the importance of nap mats as a source of these chemicals. Many childcare centres serving young children use polyurethane foam mats for the children's naptime. Until recently, the vast majority of these mats sold in the United States contained flame-retarded polyurethane foam to meet California Technical Bulletin 117 (TB117) requirements. With the 2013 update of TB117, allowing manufacturers to meet flammability standards without adding FRs to filling materials, FR-free nap mats have become widely available. We conducted an intervention study by actively switching out FR-treated nap mats with FR-free nap mats and measuring FR levels in indoor air and dust before and after the switch-out. The predominant FRs found in dust and indoor air were 2-ethylhexyl tetrabromobenzoate (EHTBB) and tris(1-chloro-2-propyl) phosphate (TCIPP), respectively. Nap mat samples analysed from four of the six centres contained a Firemaster^® mixture, while one mat was predominantly treated with tris(1,3-dichloroisopropyl) phosphate (TDCIPP) and the other contained no detectable target FRs. After replacement, there was a significant decrease (p = 0.03-0.09) in median dust concentrations for bis(2-ethylhexyl) tetrabromophthalate (BEHTBP), EHTBB, tris(4-butylphenyl) phosphate (TBPP), and TDCIPP with reductions of 90%, 79%, 65%, and 42%, respectively. These findings suggest that the nap mats were an important source of these FRs to dust in the investigated childcare environments and that a campaign of swapping out flame-retarded mats for FR-free ones would reduce exposure to these chemicals. While calculated exposure estimates to the investigated FRs via inhalation, dust ingestion, and dermal absorption were below established reference dose values, they are likely underestimated when considering the toddlers' direct contact to the mats and personal cloud effects.

Organophosphate esters and phthalate esters in human hair from rural and urban areas, Chongqing, China: Concentrations, composition profiles and sources in comparison to street dust

Human hair and street dust from rural and urban areas in Chongqing were collected to analyze Organophosphate esters (OPEs) and phthalate esters (PAEs). Concentrations of OPEs in urban hair were significantly higher than those in rural hair, whereas PAEs concentrations in rural hair were significantly higher than those in urban hair. Different composition patterns of OPEs were observed in rural and urban hair, where tris (2-chloroisopropyl) phosphate (TCIPP), tris (butyl) phosphate (TNBP) and triphenyl phosphate (TPHP) were the dominating analogues in rural hair, accounting for 62.1% of the OPEs burden, and tris (methylphenyl) phosphate (TMPP) exhibited a high contribution in urban hair, responsible for 51.3% of total OPEs, which differed from the composition profiles in corresponding street dust. Analogous composition patterns of PAEs were found in hair of both areas. Di-(2-ethylhexyl) phthalate (DEHP), dibutyl phthalate (DNBP), diisobutyl phthalate (DIBP) and diethyl phthalate (DEP) were the most abundant analogues in hair samples, while DEHP was the predominant analogue in dust samples. No clear tendency was obtained between the increasing ages and the concentrations of both compounds. Most OPEs and PAEs congeners showed significantly positive correlation with one another in rural hair. On the contrary, different correlation patterns were observed in urban hair for OPEs and PAEs, indicating multiple or additional sources existed in urban areas. Significant correlations of OPEs and PAEs were found between hair and corresponding street dust samples, but poor correlations of OPEs and PAEs were observed between rural hair and rural indoor dust, suggesting that street dust may be a predominant exogenous source for human exposure to OPEs and PAEs in this area.

Polycyclic aromatic hydrocarbons in house dust and surface soil in major urban regions of Nepal: Implication on source apportionment and toxicological effect

Urban centers have turned to be the provincial store for resource consumptions and source releases of different types of semi-volatile organic compounds (SVOCs) including polycyclic aromatic hydrocarbons (PAHs), bringing about boundless environmental pollutions, among different issues. Human prosperity inside urban communities is unambiguously dependent on the status of urban soils and house dusts. However, environmental occurrence and sources of release of these SVOCs are challenging in Nepalese cities, as exceptionally very limited data are accessible. This motivated us to explore the environmental fate, their source/sink susceptibilities and health risk associated with PAHs. In this study, we investigated the contamination level, environmental fate and sources/sink of 16 EPA's priority pollutants in surface soil and house dusts from four major cities of Nepal. Additionally, the toxicological effect of individual PAH was studied to assess the health risk of PAHs. Generally, the concentrations of ∑₁₆PAHs in surface soil were 1.5 times higher than house dust, and ranged 767-6770ng/g dry weight (dw) (median 1810ng/g dw), and 747-4910 dw (median 1320ng/g dw), respectively. High molecular weight-PAHs both in soil and dust were more abundant than low molecular weight-PAHs, suggesting the dominance of pyrogenic source. Moderate to weak correlation of TOC and BC with PAHs in soil and dust suggested little or no role of soil organic carbon in sorption of PAHs. Source diagnostic ratio and principal component analysis indicated fossil fuel combustion, traffic/vehicular emissions and combustion of biomass are the principal sources of PAHs contamination in Nepalese urban environment. The high average TEQ value of PAHs in soil than dust suggested high risk of soil carcinogenicity compared to dust.

Environmental concentration and atmospheric deposition of halogenated flame retardants in soil from Nepal: Source apportionment and soil-air partitioning

While various investigations have been driven on polybrominated diphenyl ethers (PBDEs) and other flame retardants (FRs) in different framework around the world, information about contamination and fate of PBDEs and other FRs in developing countries especially in the Indian subcontinent is uncommon. Nepal being located in the Indian subcontinent, very little is known about contamination level of semi-volatile organic pollutants discharged into the environment. This motivated us to investigate the environmental fate of halogenated flame retardant (HFRs) in Nepalese condition. In this study, we investigated the concentration, fate, and sources of 9 PBDEs, 2 dechlorane plus isomers (DPs), and 6 novel brominated flame retardants (NBFRs). Moreover, air-soil exchange and soil-air partitioning were also evaluated to characterize the pattern of air-soil exchange and environmental fate. In general, the concentrations of NBFRs in soil were more prevalent than PBDEs and DPs, and accounted 95% of ∑HFRs. By and large, the concentrations of NBFRs and DPs were measured high in Kathmandu, while PBDEs level exceeded in Pokhara. Principal component analysis (PCA) study suggested contributions from commercial penta-, octa-, and deca-BDEs products and de-bromination of highly brominated PBDEs as the significant source of PBDEs. Likewise, low f_anti ratio suggested DPs in soil might have originated from long-range atmospheric transport from remote areas, while high levels of decabromodiphenyl ethane (DBDPE) in soil were linked with the use of wide varieties of consumer products. The estimated fugacity fraction (ff) for individual HFR was quite lower (<0.05) than equilibrium value, suggesting that deposition and net transport from air to the soil is overwhelming. Soil-air partitioning study revealed neither octanol-air partition coefficient (K_OA) nor black carbon partition coefficient (K_BC-A) is an appropriate surrogate for soil organic matter (SOM), subsequently, absorption by SOM has no or little role in the partitioning of HFRs.

Concentration and spatial distribution of organophosphate esters in the soil-sediment profile of Kathmandu Valley, Nepal: Implication for risk assessment

Despite the fact that soil and sediments, which act as a sink or potential source of organic pollutants, have been polluted with organophosphate esters (OPEs) around the globe, extremely constrained data is accessible on environmental concentration and fate of OPEs in solid matrices in whole of the South Asia particularly if there should be an occurrence in Nepal. In this study, surface soil (N=19) and sediments samples (N=20) were analyzed for eight different OPE in Kathmandu Valley during October 2014. The concentration of ∑₈OPE measured in sediments samples was 12 times higher than soil and ranged 983-7460ng/g dw (median 2210ng/g dw) and 65-27,500ng/g dw (186ng/g dw), respectively. TMPP was most abundant in soil followed by TCIPP, TEHP and EHDPHP and ranged 17-25,300ng/g dw (41.3ng/g dw), 11.2-911ng/g dw (31.7ng/g dw), 8.52-858ng/g dw (26.1ng/g dw) and 10.2-114ng/g dw (25.6ng/g dw), respectively. TEHP was most prevalent in sediments followed by TMPP and EHDPHP and were in the range of 657-3020ng/g dw (median 1140ng/g dw), 267-2630ng/g dw (median 815g/g dw), 34-418ng/g (median 131ng/g dw), respectively. The sources of the high level of OPEs in soil was related to the end point use of consumer materials, traffic emission, and close proximity to commercial and industrial areas; while domestic sewage discharges and effluents from carpet industry were identified as the possible entry of OPE in sediments. Total organic carbon (TOC) and black carbon (BC) content in soil were moderately and positively correlated with ∑₈OPE indicating more or less influence of soil organic carbon. The health risk assessment suggested dermal absorption of OPEs via soil is the primary pathway of human exposure to the general population. The significantly high-risk quotient (RQ) estimated for ∑₈OPEs especially TMPP and TPHP suggested significant potential adverse risk for aquatic organisms.

Organophosphate ester flame retardants in Nepalese soil: Spatial distribution, source apportionment and air-soil exchange assessment

Despite soil being the major terrestrial environmental reservoir and one of the significant sinks for many hydrophobic organic compounds including organophosphate ester flame retardants (OPFRs), limited information is available about concentration and fate of OPFRs contamination in urban soil in general and especially in case of Nepal. This study investigates the environmental concentration, spatial distribution and source apportionment of eight OPFRs in surface soil (n = 28) from four major cities of Nepal with special interest on air-soil exchange. Overall, significantly high concentrations of ∑₈OPFR were measured in soil ranging from 25-27,900 ng/g dw (median 248 ng/g dw). In terms of compositional pattern, tris(methyl phenyl) phosphate (TMPP) was the most abundant phosphorus chemical in soil, followed by tris(2-chloroisopropyl) phosphate (TCIPP), and accounted for 35-49% and 8-25% of ∑₈OPFRs, respectively. The high level of these OPFRs was attributed to local sources as opposed to transboundary influence from remote areas. A Spearman's rank correlation analysis exhibited weak correlation of ∑₈OPFRs with TOC (Rho = 0.117, p < 0.05) and BC (Rho = 0.007, p < 0.05), suggesting little or no influence of TOC and BC on the concentration of ∑₈OPFRs. The fugacity fraction (ff) results indicated a strong influence of soil contamination on atmospheric level of OPFRs via volatilization.