Organophosphate Esters Concentrations Research Articles

Inference of Organophosphate Ester Emission History from Marine Sediment Cores Impacted by Wastewater Effluents.

Organophosphate esters (OPEs) have been in use as flame retardants for many decades, with their actual usage varying over time. Knowledge of the emission history of OPEs is valuable for improving our prediction of their environmental loadings and associated risks. In this study, concentrations and compositions of 10 OPEs were measured in three dated sediment cores from the Palos Verdes Shelf (PVS) off the coast of Los Angeles, which has been impacted by wastewater treatment plant (WWTP) effluents for over a century. The total OPE concentrations varied from 0.68 to 1064 ng/g along the sediment profile, with two apparent peaks. The first peak occurred in the 1970s, coinciding with peak emissions from WWTPs. The second peak appeared in the 2000s and was possibly attributed to increased consumption of OPEs as replacement flame retardants. Since downward movement of OPEs in the PVS sediment bed was retarded by their slow desorption, the reconstructed history likely provided an accurate picture of OPE emissions in Southern California and North America. These findings suggest that the near-shore marine sediments affected by WWTP effluents could serve as an environmental proxy documenting history in OPE use and emissions.

Occurrence, Distribution, and Potential Sources of Organophosphate Esters in Urban and Rural Surface Water in Shanghai, China.

In this study, the occurrence and distribution patterns of eight organophosphate esters (OPEs) were investigated in urban and rural surface water in a typical cosmopolitan city: Shanghai, China. In addition, concentration levels and removal efficiencies of seven sewage treatment plants were analyzed. The OPEs concentrations detected in urban rivers were significantly higher than those detected in rural rivers. Total OPEs ranged from 185.4 to 321ngL-1 in rural surface water and from 340 to 1688.7ngL-1 in urban, with an average of 221.8ngL-1 and 850.2ngL-1, respectively. Compared with other studies published in the world, the OPEs contamination in surface river water in Shanghai was at a moderate level. Furthermore, the potential sources of OPEs in urban surface water were investigated, and the results indicated that OPEs in urban surface water mainly came from three potential sources. In rural surface water, the OPE concentrations were uniformly distributed, so OPEs in rural surface water may came from nonpoint source pollution. Last, a preliminary environmental risk assessment and health risk assessment were conducted. The results showed low environmental risks at all sampling sites (except for sampling point R7: medium risk for algae) for the three aquatic organisms (algae, daphnia, and fish). Health risk assessment indicated a noncarcinogenic risk for diverse human groups for ƩOPEs.

Derivation of the predicted no-effect concentration for organophosphate esters and the associated ecological risk in surface water in China.

Organophosphate esters (OPEs), as re-emerging contaminants considered to be a potential health concern, are ubiquitous in the environment and have been widely investigated. However, little is known on the safe OPE concentrations in the water quality criteria for the protection of the aquatic environment, which is an indispensable part of environmental management. In the present study, aquatic acute and chronic predicted no-effect concentrations (PNECs) of six frequently detected OPEs were derived from the hazardous concentrations for 5% of species (HC5s), respectively. The acute PNECs for the selected OPEs ranged from 17.70 to 3562μg/L, while the chronic PNECs ranged from 4.6 × 10-4 to 61.85μg/L. Among these OPEs, tricresyl phosphate (TCrP) exhibited the lowest acute PNEC, while tris(1,3-dichloro-2-propyl) phosphate (TDCPP) presented chronic PNEC, which indicated that it has a higher toxicity effect on the aquatic environment. Furthermore, the aquatic ecological risks of individual OPEs (except for TDCPP) were deemed to be relatively low in Chinese surface water; however, the aquatic ecological risks of TDCPP and ΣOPEs indicated that they have potential adverse effects and should be considered as a potential health concern. The probability of 5% of aquatic organisms being affected by ΣOPEs was in the range of 0.21 to 17.39% based on the joint probability curve method.

Organophosphate esters (OPEs) in Chinese foodstuffs: Dietary intake estimation via a market basket method, and suspect screening using high-resolution mass spectrometry

Despite of the ubiquity of organophosphate esters (OPEs) in various environmental matrices, information regarding the dietary intakes of OPEs is currently limited. To better understand dietary exposure and intake, the present study investigated 11 OPE flame retardants (FRs) in 105 composite food samples divided into 9 food categories, collected in 2018 and based on the contents of a typical Chinese food market basket. Nine OPEs, including triethyl phosphate (TEP), tributyl phosphate (TNBP), tris(2-chloroethyl) phosphate (TCEP), tris(2-chloroisopropyl) phosphate (TCIPP), triphenyl phosphate (TPHP), 2-ethylhexyl-diphenyl phosphate (EHDPP), tris(2-butoxyethyl) phosphate (TBOEP), tris(2-ethylhexyl) phosphate (TEHP) and tris(methyl-phenyl) phosphate (TMPP), were measurable above the method limits of quantifications (MLOQs) in at least one of the analyzed samples. Among the 9 food categories, sweets were contaminated most severely with a mean sum (Σ) OPE concentration of 10.34 ng/g wet weight (ww). Regardless the food categories, EHDPP and TEP were the predominant OPEs with mean concentrations of 1.12 and 0.95 ng/g ww, respectively. In addition, the levels of OPEs in “processed foods” were significantly (unpaired t-test, p < 0.01) higher than those in “non-processed foods”. Based on the measured OPE concentrations, we estimated daily per capita dietary intakes of ΣOPEs for Chinese adult population to be 44.3 ng/kg bw/day, that was mainly contributed by TCEP (14.3 ng/kg bw/day), TEP (12.7 ng/kg bw/day) and EHDPP (8.4 ng/kg bw/day). In addition to these 9 detected OPEs, further suspect screening in the combined extracts of foodstuffs by use of high-resolution spectrometry revealed a novel OP-FR, triphenyl phosphine oxide (TPPO). The highlight findings in this study were: 1) the amount of OPE via dietary intakes for the Chinese population is generally in the same order of magnitude as for other countries, i.e. the Swedish, Belgian and Australian adult population, and far less than the reference dosage value of each OPE (hazard index ≪ 1); 2) the total dietary intakes of OPEs were dominated by cereals, approximately accounting for 52.2%; and 3) the first reported detection of the novel OP-FR, TPPO, in foodstuff samples.

Concentrations, sources and human exposure implications of organophosphate esters in indoor dust from South Africa

The concentrations of four organophosphate esters (OPEs) were measured in 50 dust samples from homes (n = 10), offices (n = 9), university computer laboratories (n = 12) and cars (n = 19) in Durban, South Africa. The median concentrations Σn=4 OPEs were 22940, 26930, 19565 and 49010 ng g⁻1 in homes, offices, university computer laboratories and cars respectively. OPEs were detected in all samples with the exception of one car and one computer laboratory sample in which TDCIPP was not detected. Significant association of indoor characteristics with OPE concentrations was observed. OPEs positively correlated (r = 0.22, p value = 0.4862) with electronics and correlated (r = 0.522, p value = 0.0675) with foams and furniture in homes. By employing the median concentrations and an average dust intake rate, the exposure doses (ng d−1) were found to be 169 (TCEP), 74 (TCIPP), 162 (TDCIPP) and 55 (TPHP) for adults; 159 (TCEP), 70 (TCIPP), 108 (TDCIPP) and 57 (TPHP) for teenagers; 317 (TCEP), 152 (TCIPP), 334 (TDCIPP) and 94 (TPHP) for toddlers. The predominance and exposure magnitude of OPEs in the South African environment require further investigations to determine cumulative human health effects arising from mixtures of these compounds through multiple exposure routes.

Occurrence of organophosphate esters and their diesters degradation products in industrial wastewater treatment plants in China: Implication for the usage and potential degradation during production processing

Influent, effluent and sludge samples were collected from eight industrial wastewater treatment plants (WWTPs) in the Pearl River Delta, China. Samples were investigated for the occurrence of 10 organophosphate esters (OPEs) and 7 organophosphate diesters (Di-OPs). Most of the 10 OPEs were detected at total concentrations of OPEs (∑OPEs) ranging from 65.8 to 2842 ng L−1 in influent samples and exhibited different composition profiles. The results indicated that OPEs were widely used with different proportions in versatile OPE-containing products. Meanwhile, ∑OPEs in effluent were found in the range of 6.37–2710 ng L−1; these residuals were subsequently transported to municipal WWTPs for further treatment and posed extra pressure on the plants. Seven Di-OPs, possible degradation products of the OPEs, were also detected in influent, effluent and sludge. The results suggested that OPEs underwent degradation during rigorous industrial manufacturing procedures, such as thermal processes, highly alkaline pH, or processes that involved metal/metal oxide. In addition, high levels of dibutyl phosphate, di(2-ethylhexyl) phosphate and diphenyl phosphate were found in influent suggesting their possible industrial application.

Organophosphate flame retardants in total suspended particulates from an urban area of zhengzhou, China: Temporal variations, potential affecting factors, and health risk assessment

Organophosphate esters (OPEs) are widely used as flame retardants and plasticizers in industry and daily life, but the partition of OPEs to particles is still unclear because of the wide range of their physicochemical properties. In this study, six target OPEs with different vapor pressures (log PL) were measured from 30 total suspended particulate (TSP) samples collected from an urban area of Zhengzhou from June to November in 2018. The total concentration of OPEs ranged from 0.30 to 3.46 ng/m3, with average concentration of 1.04 ng/m3. Tris (chloroethyl) phosphate (TCEP), tris(2-chloroisopropyl) phosphate (TCPP), and tributyl phosphate (TnBP) were most abundant in TSP, accounting for approximately 86.0% to the total OPEs. The temporal variations showed a specific trend that OPE concentrations in TSP were much higher in autumn than those of summer. Significant positive correlations were observed between TSP concentration in air and the total concentration of OPEs in TSP, with r up to 0.596. Particle concentrations caused major changes on OPE concentrations in TSP with octanol-air partition coefficient (log KOA) between 7.7 and 10 but had no significant influence on the OPEs with log KOA higher than 12. Temperature had significant influence on the total and individual OPEs with high vapor pressures (log PL > −4.0), indicating that log KOA and log PL had significant influence on the OPE concentrations in TSP and may be one of the key factors on their temporal variations. Temperature had significant influence on OPE concentrations in TSP due to the strong temperature dependency of log KOA and log PL. No significant relationships were found between the wind speed and OPE concentrations in TSP, suggesting that OPEs detected in TSP might be emitted from the local sources. The hazards quotient (HQ) values were 6–8 orders of magnitude lower than 1, indicating that there was a low risk to local residents from the exposure to OPEs in TSP. This study preliminarily illuminates the potential affecting factors on the temporal variations of OPEs in TSP. It would be helpful for investigating the gas-particle partitioning behaviors and human health risks of OPEs in air.

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.

Pollution Characteristics of OPEs in the Surface Water and Sediment of the Jinjiang River in Chengdu City

New GC-MS methods were developed for seven typical organophosphate esters (OPEs) including tri-n-butyl phosphate (TnBP), tris (2-ethylhexyl) phosphate (TEHP), tributoxyethyl phosphate (TBEP), triphenyl phosphate (TPhP), tri (2-chloroethyl) phosphate (TCEP), trichloropropyl phosphate (TCPP) and tridichloropropyl phosphate (TDCPP). These methods were used to quantify their concentrations in the surface water and sediment from the Jinjiang River, Chengdu. The recoveries of the target substances were 76%-119% (surface water)and 83%-126% (sediments). Total OPEs (Σ7OPEs) ranged from 689.09 to 10623.94 ng·L-1, with the mean of 3747.58 ng·L-1 in the surface water. The pollution level of each monomer was in the order TBEP > TCEP > TPhP > TEHP > TCPP > TnBP. TBEP was the predominant pollutant, accounting for 36.50%-95.90% of the Σ7OPEs concentrations. The contents (dw) of the Σ7OPEs ranged from 25.52 to 296.00 ng·g-1 in sediments, and TBEP was also the main pollutant in these samples. No significant correlation existed between the concentrations of OPEs in the surface water and sediments. Alkyl OPEs were the main pollutants in the surface water and sediments. The distribution of OPEs was influenced by the source of emissions and environmental attributes. The pairs TCPP and TnBP, TBEP and TEHP, and TCEP and TPhP might have common sources in the surface water.

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 1600ng/g dry weight, with a median of 292, 476, 203, and 48.8ng/gdw 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 (90-150μm) (340ng/gdw) and F5 (< 75μm) (305ng/gdw), 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.

Threats of organophosphate esters (OPEs) in surface water to ecological system in Haihe River of China based on species sensitivity distribution model and assessment factor model.

Organophosphate esters (OPEs) are a kind of emerging contaminants, but the information about their pollution profile and ecological risk are still scarce in China. In this study, 31 surface water samples of Haihe River (China) were collected in November 2017, and 11 OPEs were measured, and the ecological risk of OPEs was assessed by means of species sensitivity distribution (SSD) method and assessment factor method. Additionally, Pearson correlation analysis and an international comparison with other rivers in the world were conducted. The results showed that total OPEs ranged from 23.98 to 824.72ngL-1, and the mean value was 228.70ngL-1. The concentration of OPEs decreased as follows: Tri(2-chloroisopropyl) phosphate (TCPP) > Tri(2-chloroethyl) phosphate (TCEP) > Triethyl phosphate (TEP) > Tributoxyethyl phosphate (TBEP) > Triphenyl phosphate (TPhP) > Tripropyl phosphate (TPrP) > Tri(2-ethylhexyl) phosphate (TEHP) > 2-ethylhexyl diphenyl phosphate (EHDPP) > Tri(1,3-dichloro-2-propyl)phosphate (TDCPP) > Tri-n-butyl phosphate (TnBP) > Tri-m-cresyl phosphate (TMPP). TCPP (19.54-160.82ngL-1) and TCEP (N.D.-151.99ngL-1) with the mean value of 76.67 and 53.13ngL-1 respectively were identified as the richest OPEs in Haihe River. The concentration of OPEs slowly increased in the upper reaches of Haihe River, and it tended to be stable in the middle reaches of Haihe River and decreased rapidly from the downstream to the outer sea. Significantly positive correlations occurred among three chlorinated alkyl OPEs (TCEP, TCPP, and TDCPP), suggesting that they might come from the same source. Based on the comparison, the pollution condition of OPEs in Haihe River was low, and TCEP was found to be the most abundant OPEs in China but it was not that in Europe. The ecological risk assessment on the basis of assessment factor method suggested that the risk of OPEs in Haihe River for algae, crustacean, and fish was limited. In addition, the results of SSD method suggested that the combined ecological risk of four OPEs in Haihe River was also low. This study provides information about the pollution status of OPEs in the surface water of China to some extents and a project for the risk estimation based on SSD for prior and emerging flame retardants.

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.

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

BackgroundExposure to organophosphate ester (OPE) flame retardants and plasticizers is widespread and is of concern due to their toxicity. ObjectivesTo 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. MethodsWomen 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. ResultsFive-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. ConclusionsHandheld electronic devices, notably cell phones, may either be sources or indicators of OPE exposure through hand-to-mouth and/or dermal uptake.

Organophosphate esters in biota, water, and air from an agricultural area of Chongqing, western China: Concentrations, composition profiles, partition and human exposure

We measured the concentrations of organophosphate esters (OPEs) in some biotic samples which can serve as human foodstuffs and ambient environments including air and river water from an agricultural area of Chongqing, western China. Fish samples exhibited highest OPEs levels (960 ng/g lipid weight) among the biota, followed by chicken (676 ng/g lw), cattle (545 ng/g lw) and pigs (535 ng/g lw). Tributyl phosphate (TNBP), tris (2-methylpropyl) (TIBP) and chlorinated OPEs were the major analogs in biotic samples, which appeared similar with the patterns from river water and outdoor air, but apparently different from indoor air. To further investigate the influence of ambient environment on the distribution of OPEs in biota, we analyzed the correlation between OPEs concentrations in ambient environment and biological samples, and the results revealed that most of the samples (except for pig samples) heavily correlated with outdoor air, whereas only fish and cattle samples were strongly correlated with river water. The partitioning behaviors of OPEs among biota, air and river water were also studied through calculating the biota-water accumulation factors (BWAFs), biota-air accumulation factors (BAAFs) and air-water partitioning factor (AWPFs). Significantly linear correlations (P < 0.05) were observed between log (BWAFs) and log (KOW) values, and between log (AWPFs) and log H (Henry's law constants), nevertheless log (BAAFs) was increasing along with the log (KOA) values. The daily intake (DI) values were estimated via foodstuffs ingestion and environmental exposure. The estimated DI values of OPEs from food and ambient environments were 1.78 ng/kg-bw/day, 1.23 ng/kg-bw/day and 1.42 ng/kg-bw/day in toddlers, children and adults, respectively, which lay at the low end of the reported data and well below the reference dose (RfD).

Temporal variations and potential sources of organophosphate esters in PM2.5 in Xinxiang, North China

We monitored the concentrations of 10 organophosphate esters (OPEs) in 52 fine particulate matter (PM2.5) samples in Xinxiang, Henan Province, North China, in 2015. During the sampling period, the OPE concentrations in most samples (n = 47) differed minimally and were relatively stable (mean: 2.02 ± 0.93 ng m−3), although several samples (n = 5) had high total OPE (Ʃ10OPE) concentrations (mean: 9.99 ± 5.69 ng m−3), which may have been influenced by high PM2.5 levels. Meanwhile, some samples had high PM2.5 concentrations but low Ʃ10OPE concentrations (i.e. low OPE/PM2.5 ratios) or low PM2.5 concentrations but high Ʃ10OPE concentrations, which might have been influenced by air mass sources. Therefore, we assessed air mass sources using the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model and wind direction frequency data, and subsequently analysed PM2.5 and OPE sources using a potential source contribution function (PSCF) model. The results revealed that air mass sources couldn't represent the source of specific pollutants, including PM2.5 and OPEs. Generally, both PM2.5 and OPEs were from Henan and Shandong Provinces; however, the major source areas differed, which may have resulted from diverse pollution characteristics in various source areas. The principal component analysis and PSCF results revealed that the 10 OPEs could be segmented into three groups, which were associated with different source areas. These results suggested that pollution characteristics of contaminants in source areas should be considered in source apportionment.

Concentrations of Organophosphate Esters and Their Specific Metabolites in Food in Southeast Queensland, Australia: Is Dietary Exposure an Important Pathway of Organophosphate Esters and Their Metabolites?

There were several studies that measured organophosphate esters (OPEs) in foods to assess the dietary intake of OPEs but none has measured OPE metabolites (mOPEs) in the same samples. In this study, we measured the concentrations of OPEs and mOPEs in 87 food samples and in five tap water samples collected in Queensland, Australia belonging to eight food groups. Tris(2-chloroisopropyl) phosphate (TCIPP) (detection frequency (DF), 77%) and tributyl phosphate (TBP) (DF, 71%), were the most frequently detected OPEs, while dibutyl phosphate (DBP) (DF, 84%) and diphenyl phosphate (DPhP) (DF, 86%) were the most frequently detected mOPEs. Vegetables had the highest concentrations of both ∑9OPEs and ∑11mOPEs, with the mean concentrations of 2.6 and 17 ng/g wet weight. Compared with dust ingestion and inhalation, dietary intake was the most important exposure pathway for tris(2-chloroethyl) phosphate (TCEP) (4.1 ng/kg bw/day), TCIPP (25 ng/kg bw/day), and TBP (6.7 ng/kg bw/day), accounting for >75% of total intake. Furthermore, we found that the intakes of some mOPEs, that is, bis(1,3-dichloroisopropyl) phosphate (BDCIPP) and DPhP from diet were typically higher than that of their parent OPEs. Such high levels of mOPE intakes could interfere with the utilization of mOPEs as biomarkers for assessing OPE exposure and warrant further investigation.

Spatial and temporal distribution of organophosphate esters in the atmosphere of the Beijing-Tianjin-Hebei region, China

High volume air samples were collected from April 2016 to March 2017 at five locations across the Beijing-Tianjin-Hebei (BTH) region, to investigate the atmospheric occurrence of organophosphate esters (OPEs). The mean atmospheric concentrations of ∑8OPEs (gas and particle phases) varied from 531 ± 393 pg/m3 to 2180 ± 1490 pg/m3 with the highest level observed at the urban sampling site in Tianjin City. ∑8OPEs were predominated by the chlorinated OPEs (TCEP, TCPP, and TDCIPP), which accounted for 60% ± 16% of the OPE concentrations across the BTH region. Generally, higher levels of gaseous OPEs were found in summer, while higher levels of particle-bound OPEs were observed in winter. The concentrations of gaseous OPEs were positively and significantly correlated with local temperatures (p < 0.05) and relative humidity (p < 0.01), while significantly positive correlations were found between concentrations of particle-bound OPEs and total suspended particulates (TSP) (p < 0.01). These findings confirmed that temperatures, relative humidity and levels of TSP are the main drivers for OPE distributions in different seasons and areas. Gas/particle partitioning of OPEs was also investigated based on the absorption-partitioning model (octanol–air partitioning coefficient (Koa) -based model) and Junge–Pankow adsorption-partitioning model (J-P model). Koa-based model generally showed a better performance in comparison with the measured results. The assessment of inhalation exposure risks indicated that relatively higher exposure risks were found in the urban areas, in particular, in Tianjin City (a median value of the estimated daily intake (EDI) of 106 pg/kg body weight/day), suggesting that more attention should be drawn to OPE distributions in the heavily industrialized megacities.

Size-dependent concentrations and bioaccessibility of organophosphate esters (OPEs) in indoor dust: A comparative study from a megacity and an e-waste recycling site

Indoor dust ingestion is an important pathway in human exposure to environmental pollutants, and the bioaccessibility of pollutants can largely influence human exposure risk assessment. In the present study, the concentrations and compositions of organophosphate esters (OPEs) were investigated for different sizes (50 μm to 2 mm) of indoor dust collected from a megacity, Guangzhou, and an e-waste recycling site. The concentrations of total OPEs were 5360 to 6830 ng/g and 560 to 20,500 ng/g across all sizes of dust from Guangzhou and the e-waste site, respectively. The levels and compositions of OPEs were consistent in different fractions of dust from Guangzhou. The highest concentrations of OPEs were found in the finest fraction of dust from the e-waste site. OPEs in Guangzhou dust showed decreasing bioaccessibility when the log KOW of FRs increased from 4 to 11. The bioaccessibility of most OPEs in dust from the e-waste site was much lower than those in Guangzhou dust, indicating low bioaccessibility in the components of dust, such as e-waste debris, from the e-waste site. The human exposure risks of OPEs in dust from Guangzhou were generally higher than those in dust from the e-waste site. Chitosan and montmorillonite could significantly decrease the bioaccessibility of all OPEs, except for tri-ethyl phosphate (TEP) and tris‑(2‑butoxyethyl) phosphate (TBOEP) in dust (p < 0.05), indicating chitosan and montmorillonite as promising food additives to enhance the elimination of OPEs.

Exposure to Organophosphate Esters and Brominated Flame Retardants: What Does Your Cell Phone Tell You?

BackgroundWidespread exposure to organophosphate esters (OPEs), used as flame retardants and plasticizers, is of concern due to emerging data on toxicity. We aimed to identify OPE concentrations and pathways of exposure to Canadian pre-menopausal women, and to compare that with brominated flame retardants (BFRs).MethodsFrom 51 women in Toronto and Ottawa, we measured concentrations of OPEs in air and floor dust in their homes, and on their hands and their electronic devices. 557 samples were analyzed for 23 OPEs, 9 &amp;#8220;novel&amp;#8221; brominated flame retardants and 14 PBDE congeners. Also, urine samples from 44 participants were analyzed for 8 OPE metabolites.Results and DiscussionOPE air and dust concentrations were in the low ng/m3 and µg/g ranges, respectively, for 5-8 OPEs with &amp;gt;80% detection frequency. BFRs were ~100X lower. Eight OPEs also had &amp;gt;80% detection frequency on hands (up to µg/cm2 levels) that were similar in samples taken 3 weeks apart. Handheld electronic devices (e.g., cell phone, tablet) had significantly higher OPE (but not BFR) concentrations than non-handheld devices (e.g., TV, desk top). OPE concentrations on hands were most frequently correlated with those on cell phones, whereas BFRs on hands were correlated with laptops. Moreover, we found a significant correlation between total &amp;#8721;OPE concentrations on cell phones and those in the corresponding urine sample, driven mostly by Triphenyl Phosphate (TPhP). We also found a significant correlation between the parent compound TDCPP in dust and cell phones and the corresponding urinary metabolite. Only TCPP on hands was correlated with its urinary metabolite.ConclusionsOur study confirmed widespread exposure to OPEs among Canadian women. We found that OPE exposure could in part be explained by levels found on a woman&amp;#8217;s cell phone and secondarily by concentrations in her residential floor dust and her hands. It is not clear whether the cell phones are acting as a source or indicator of exposure to OPEs.

Levels, distribution, and sources of organophosphate flame retardants and plasticizers in urban soils of Shenyang, China.

Seventy-four soil samples from the road greenbelts, residential areas, drylands, waste grasslands, education lands, industrial areas, city parks, and rural homesteads of Shenyang city, China, were collected and analyzed for 13 organophosphate esters (OPEs). OPEs were detected in all analyzed soil samples, which indicate that OPEs are ubiquitously environmental contaminants. The ∑13OPEs concentrations ranged from 0.039 to 0.95mg/kg dry weight (dw), with the mean and median concentrations of 0.23 and 0.16mg/kg dw, respectively. The pollution levels of OPEs in different land use types were different; the concentrations of OPEs in dryland soils were maximum and in city park soils were minimum. Of 13 OPEs, tri-iso-butyl phosphate (TiBP), tris-(1-chloro-2-propyl) phosphate (TCPP), tri-butoxyethyl phosphate (TBEP), and tris[2-chloro-1-(chloromethyl) ethyl] phosphate (TDCP) were the most abundant OPEs, contributing 42.0 ± 12.8, 12.4 ± 2.32, 6.31 ± 1.88, and 5.76 ± 1.86% of ∑13OPEs, respectively. Principal component analysis (PCA) and absolute principal component score-multiple linear regression (APCS-MLR) suggested that OPE pollution in soils may be derived from atmospheric deposition, road runoff and vehicular traffic emission, and wastewater/reclaimed water irrigation and sludge application, their contributions were accounting for 62.4, 17.6, and 20.0%, respectively. As compared to the results from other studies, the pollution of OPEs in the urban soils of Shenyang is relatively serious.