Pollution profiles, influencing factors, and source apportionment of target and suspect organophosphate esters in ambient air: A case study in a typical city of Northern China

Key genes and microbial ecological clusters involved in organophosphate ester degradation in agricultural fields of a typical watershed in southwest China

Organophosphate esters (OPEs) are widely used as flame retardants and plasticizers, and they have raised global concern due to their persistence, bioaccumulation, and potential toxicity. However, OPE contamination characteristics and microbial degradation mechanisms in agricultural soils remain poorly understood. This study investigated agricultural soils from the riparian zone of the Anning River Basin in southwest China. The concentrations of 12 OPEs were determined using gas chromatography-tandem mass spectrometry. The results revealed that the total OPE concentration was moderate, with triethyl phosphate being the most abundant compound. Metagenomic techniques and Bayesian linear regression analysis were employed in combination with the Kyoto Encyclopedia of Genes and Genomes database to identify potential degradation pathways for triethyl phosphate and tris (2-chloroethyl) phosphate. The phoA, phoB, phoD, and glpQ genes, which encode phosphatases, catalyze ester bond cleavage, thereby facilitating the degradation of OPEs. Further microbial interaction network analysis identified core OPE-degrading microorganisms, including Pimelobacter simplex, Nocardioides sp. JS614, Nocardioides daphniae, and Methylocystis heyeri. Additionally, neutral community models indicated that environmental selection drives microbial community structure. In conclusion, this study provides an in-depth understanding of OPE contamination and its microbial degradation mechanisms in agricultural soils, offering theoretical insights for pollution management and remediation strategies.

Aqueous secondary formation substantially contributes to hydrophilic organophosphate esters in aerosols

Chemicals of emerging concern (CECs), like organophosphate esters (OPEs), are toxic substances threatening human and wildlife health. Yet the atmospheric transformation of CECs remains poorly understood. Here we combine field measurements and partitioning models to reveal that OPEs could be enhanced by aqueous-phase processes in aerosols. We show that hydrophobic OPEs are absorbed favorably into the organic phase, whereas hydrophilic OPEs preferably partition into the aqueous phase. We provide field evidence that enhanced aqueous secondary formation of OPEs occurs in winter, and its magnitude is strongly dependent on aerosol water content. We suggest that dissolved inorganic salts and transition metals in aerosols positively impact the formation of particle-bound hydrophilic OPEs, by facilitating aqueous partitioning and/or oxidation. Our findings highlight the important role of aqueous oxidation chemistry for the fate of CECs in the atmosphere, urging better consideration of transformation products in future risk assessment and chemical management.

Traditional and novel organophosphate esters in atmosphere of greenhouse covered with mulch films: Seasonal variations, partitioning and exposure risks

Mulch films play a critical role in the accumulation of organophosphate esters (OPEs) in greenhouse soils. However, their impact on the occurrence, partitioning and health risks of atmospheric OPEs is unclear. This study fully investigated multi-media distributions of eleven traditional OPEs and four novel OPEs in greenhouses covered with degradable mulch films. The atmospheric concentrations exhibited substantial variability, ranging from 539 to 14821 pg/m³ in the gas phase and from 242 to 8320 pg/m³ in the particle phase, with summer levels higher than winter levels. Significant correlations (p < 0.05) were detected between OPE concentrations in mulch films and in air, indicating mulch films as a major source. First-order kinetic model effectively characterized the release patterns of dominant congeners including triphenyl phosphate and tris(2,4-ditert-butylphenyl) phosphate from degradable films. The Li-Ma-Yang model showed superior predictive capability for gas-particle partitioning than the Harner-Bidleman model. Total concentrations of OPEs in uncoated soils were at a range of 274-955 μg/kg. Soil-air exchange behaviors of OPEs governed by inherent volatility exhibited a seasonal dependence. While non-carcinogenic risks of OPEs for greenhouse farmers via air inhalation and dermal contact were negligible, holistic health assessments should integrate other uptake pathways and consider transformation products of OPEs.

A Novel Organophosphate Ester, Tris(2,4-ditert-butylphenyl) Phosphate, Induced Reproductive Toxicity in Male Zebrafish at Environmentally Relevant Concentrations

As a novel organophosphate ester (NOPE), tris(2,4-ditert-butylphenyl) phosphate (TDtBPP) has attracted significant attention due to its unexpectedly high detection in natural environments. However, the ecological toxic effects of environmentally relevant concentrations of TDtBPP in organisms remain entirely unknown. In this study, 1 month old zebrafish were exposed to 0, 50, 500, or 5000 ng/L TDtBPP for 150 days, and the reproductive toxicity in male fish was evaluated. Results demonstrated that TDtBPP exposure significantly inhibited the maturation of spermatozoa and thus decreased spermatogenesis. Furthermore, abnormal sperm morphology and decreased sperm motility were also observed. The decrease in sperm quantity and quality eventually resulted in the declining fecundity. Moreover, TDtBPP exposure downregulated the expression of hsd3b1 in vivo and in vitro and subsequently inhibited the synthesis of androgens in zebrafish testes and Leydig cells. This inhibition of androgen synthesis appeared to be responsible for the observed reproductive toxicity in male fish. Molecular docking and dual-luciferase reporter gene experiments elucidated that TDtBPP inhibited the promotion of vitamin D on hsd3b1 transcription by the vitamin D receptor and thus downregulated the expression of hsd3b1. Our findings provide first time evidence that TDtBPP poses a risk to male fish reproduction at environmentally relevant levels.

Potential impact of organophosphate esters on thyroid eye disease based on machine learning and molecular docking

Organophosphate esters (OPEs) are widely used as flame retardants and plasticizers in daily commodities and building materials. Some OPEs, acting as agonists of the thyroid-stimulating hormone receptor (TSHR), may contribute to the development of thyroid eye disease (TED). This study analyzes the serum and urine of patients and control groups, using machine learning and molecular docking to investigate the potential impact of OPEs on TED. Results indicate significantly higher concentrations of OPEs and di-OPEs of TED patients compared to controls (Mann-Whitney U test, p < 0.05). Aryl OPEs exhibit the strongest binding affinity with TSHR. We developed a predictive model for OPE-TSHR affinity to explore the impact of OPE structural features on TSHR activity and effectively capture the complex relationships between changes in OPE side chains and their effects on TSHR. Predictions from the USEPA's database indicate that 28 % of 1011 OPEs have a tendency to bind with TSHR. Furthermore, a high-accuracy classification model successfully identified key substructures associated with high affinity for TSHR. This study not only enhances our understanding of the complex relationship between the structural diversity of OPEs and their thyroid impact but also offers molecular design insights to prevent releasing OPEs with high thyroid harm potential into the environment.

Organophosphate esters in vehicle interior dust from Chinese urban areas: What are the influencing factors of the occurrence?

Organophosphate esters (OPEs) are a class of semi-volatile organic compounds frequently used to various products as flame retardants and plasticizers. As emerging pollutants, OPEs have attracted significant attention due to their potential impacts on human health and ecosystems. This study investigated the occurrence of OPEs in vehicle interior dust across 36 cities in China. The primary aims were to explore the correlations among OPE pollutants, identify potential emission sources, and examine the key factors influencing their distribution. The OPE concentrations ranged from 5450 ng/g to 63,700 ng/g, with the content of three categories of OPEs as follows: ΣChlorinated-OPEs (median: 17420 ng/g) > ΣAlkyl-OPEs (median: 3880 ng/g) > ΣAryl-OPEs (median: 1490 ng/g). In northern China, the aggregate concentration of OPEs in vehicle interior dust demonstrated higher levels compared to those in the western and mid-southeastern region, with the later two appeared to be comparable to each other. Coastal and inland cities displayed variations in OPE levels, with different representative OPEs. The occurrence of OPEs in vehicle interior dust was closely associated with regional economic development levels, motor vehicle parc, and road density. In contrast to other urban areas, first-tier cities showed the highest aggregate levels of OPEs in vehicle interior dust, with a significant increase observed specifically in the concentrations of Alkyl-OPEs and Aryl-OPEs.

A novel hybrid features grey incidence model and its application in identifying key factors influencing air pollution in Jiangsu Province

Accurately assessing the key factors influencing air pollution is crucial for effective air pollution control. To address this need, we propose a novel Hybrid Features Grey Incidence Model (HFGIM), which integrates geometric feature differences from both proximity and similarity perspectives. Firstly, we extract geometric feature difference vectors of proximity and similarity from time series data and measure the overall feature difference degree by calculating vector norms. Secondly, we calculate the relative feature differences and information contribution rates of proximity and similarity to derive the hybrid feature differences coefficient between sequences, thereby obtaining the hybrid features incidence degree. After detailing the model's properties and modelling steps, we introduce the Cross-sectional Data Hybrid Features Grey Incidence Model (C-HFGIM) and the Panel Data Hybrid Features Grey Incidence Model (P-HFGIM) for handling cross-sectional and panel data, respectively. Applying HFGIM, we identified the key pollutants and primary pollution source indicators of air pollution in Jiangsu Province. We also compared HFGIM with other classical grey incidence models to verify the proposed model's effectiveness. Based on the analysis results, we propose policy recommendations for air pollution control in Jiangsu Province.

A real-time assessment of hazardous atmospheric pollutants across cities in China and India

China and India are two of the fastest-growing developing economies covering about 35 % of the world's population. Due to the extensive prevalence of air pollution across cities in China and India, contemporary assessment of atmospheric pollution through real-time and remote sensing observations is inadequate. The study aims to determine the spatial distribution and temporal variation of hazardous atmospheric pollutants across cities in China (Shanghai, Nanjing, Jinan, Zhengzhou and Beijing) and India (Kolkata, Asansol, Patna, Kanpur and Delhi). Ground observation data on CO, O3, PM2.5, PM10, NO2 and SO2 along with remote sensing data on AOD, CO, O3, BC, NO2, SO2 and dust surface mass concentrations are used to assess atmospheric pollution. This study examines daily, zonal and longitudinal pollutant distributions using Sentinel-5 P data and surface mass concentrations over the vertical column evaluated from NASA satellite data. The Mann-Kendall test and relative change methods have been implemented to assess pollutant trends while Sen's Slope identifies the magnitude of change. The similarity test and data validation methods including NRMSE, PC and MBias have been employed to ensure consistency in analysing annual trends for each air pollutant in the datasets. Additionally, multiple correlation matrix analysis has been used to examine the associations among different pollutants from both datasets based on their annual averages. Remote sensing data reveals that eastern China and north-eastern India have the highest aerosol, BC, CO, NO2 and SO2 while western China and southern India lowest. Dust peaks in the west while O3 levels are highest in the northern part of China and India. Ground observation data indicates that Chinese cities have higher annual mean SO2 and O3 concentrations with yearly declines in PM2.5, PM10, NO2, SO2 and CO notably SO2. Indian cities witnessed overall increases in PM2.5, PM10, NO2 and SO2 from 2012 to 2019 with a slight decline in 2020 followed by a resurgence in 2023. The findings provide insights for implementing regional policy measures to reduce air pollution based on changes in pollutant behaviour. The study suggests that addressing atmospheric pollutants, particularly NO2, CO, PM2.5, PM10, and SO2 requires a comprehensive environmental policy framework involving central and state governments and enforcing stringent environmental protection laws.

Organophosphate flame retardants in Romania coastline: Occurrence, faith and environmental risk

This research comprehensively assesses phosphorus-based flame retardants (OPFRs) in seawater, sediment, and algae from the Romanian Black Sea coastline, evaluating their concentrations, distribution patterns, and potential environmental risks. OPFR concentrations ranged from 479 to 2229 ng/L in abiotic samples and 44 to 1953 ng/g dry weight in sediments, while algae samples showed concentrations between 273 and 10,301 ng/g dry weight. The most common OPFRs identified were tri-propyl phosphate (TPP), tri(2-chloroethyl) phosphate (TCEP), and tri(2-chloroisopropyl) phosphate (TCPP) in abiotic samples, with TCEP, diphenyl phosphate (DPHP), TPP, and TCPP dominating in algae. Notably, TPP reached concentrations of 1417 ng/L and 10,062 ng/g dry weight in algae. The environmental risk assessment indicated that these contaminants pose risks ranging from low to medium, highlighting a moderate concern for aquatic organisms. The findings underscore the need for ongoing monitoring and evaluation of OPFR levels in marine environments to inform management strategies and mitigate potential ecological impacts on the Black Sea ecosystem.

Nationwide profiling and source identification of organophosphate esters in Korean surface waters using target, suspect, and non-target HRMS analysis

Organophosphate esters (OPEs) are emerging contaminants that serve as alternatives to regulated substances in aquatic environments. A nationwide large-scale assessment for OPEs, including point sources, remains insufficient. To address this issue, we aimed to investigate OPEs occurrence and novel OPEs via comprehensive target, suspect and non-target analysis. Among the 11 target OPEs, 10 were detected at sampling sites distributed evenly nationwide. The highest mean concentrations were measured for tris-(2-butoxyethyl) phosphate (TBOEP) and tris(2-chloroisopropyl) phosphate (TCIPP). The multivariate statistical analysis revealed that TBOEP and TCIPP are essential components for assessing total OPEs pollution. The systematic risk assessment results evaluated the overall risk contribution of TBOEP and the significant risk impact of 2-ethylhexyl diphenyl phosphate. Promising suspect and non-target analysis enabled frequent detection and identification of 6 antioxidant transformation products (TPs), as well as the tentative identification of 14 OPEs and TPs, including 3 di-OPEs. Based on sampling site classification, we confirmed that major OPEs are significantly discharged near point sources. We believe that this is the first attempt to assess the nationwide risk and potential sources of OPEs in Korean surface waters, providing insights that could support further prioritization and regulation efforts.

Organophosphate flame retardants in air from formal e-waste recycling workshops in China: Size-distribution, gas-particle partitioning and exposure assessment

In order to understand the organophosphate flame retardants (OPFRs) pollution and evaluate the inhalation exposure risk in formal e-waste recycling facilities, the air concentrations, particle size distribution and gas-particle partitioning of OPFRs in four typical workshops were investigated. The total Σ15OPFR concentrations inside workshops were in the range of 64.7-682 ng/m3, with 5.80-23.4 ng/m3 in gas phase and 58.8-658 ng/m3 in particle phase. Triphenyl phosphate (TPHP) and tris(2-chloroisopropyl) phosphate (TCIPP) were main analogs, both of which contributed to 49.0-85.7% of total OPFRs. In the waste printed circuit boards thermal treatment workshop, the OPFRs concentration was the highest, and particle-bound OPFRs mainly distributed in 0.7-1.1 μm particles. The proportions of TPHP in different size particles increased as the decrease of particle size, while TCIPP presented an opposite trend. The gas-particle partitioning of OPFR analogs was dominated by absorption process, and did not reach equilibrium state due to continuous emission of OPFRs from the recycling activities. The deposition fluxes of OPFRs in respiratory tract were 65.7-639 ng/h, and the estimated daily intake doses of OPFRs were 8.52-76.9 ng/(kg·day) in four workshops. Inhalation exposure was an important exposure pathway for e-waste recycling workers, and deposition fluxes of size-segregated OPFRs were mainly in head airways region.

Mechanistic insights into tris(2-chloroisopropyl) phosphate biomineralization coupled with lead (II) biostabilization driven by denitrifying bacteria

The ubiquity and persistence of organophosphate esters (OPEs) and heavy metal (HMs) pose global environmental risks. This study explored tris(2-chloroisopropyl)phosphate (TCPP) biomineralization coupled to lead (Pb2+) biostabilization driven by denitrifying bacteria (DNB). The domesticated DNB achieved synergistic bioremoval of TCPP and Pb2+ in the batch bioreactor (efficiency: 98 %).TCPP mineralized into PO43- and Cl-, and Pb2+ precipitated with PO43-. The TCPP-degrading/Pb2+-resistant DNB: Achromobacter, Pseudomonas, Citrobacter, and Stenotrophomonas, dominated the bacterial community, and synergized TCPP biomineralization and Pb2+ biostabilization. Metagenomics and metaproteomics revealed TCPP underwent dechlorination, hydrolysis, the TCA cycle-based dissimilation, and assimilation; Pb2+ was detoxified via bioprecipitation, bacterial membrane biosorption, EPS biocomplexation, and efflux out of cells. TCPP, as an initial donor, along with NO3-, as the terminal acceptor, formed a respiratory redox as the primary energy metabolism. Both TCPP and Pb2+ can stimulate phosphatase expression, which established the mutual enhancements between their bioconversions by catalyzing TCPP dephosphorylation and facilitating Pb2+ bioprecipitation. TCPP may alleviate the Pb2+-induced oxidative stress by aiding protein phosphorylation. 80 % of Pb2+ converted into crystalized pyromorphite. These results provide the mechanistic foundations and help develop greener strategies for synergistic bioremediation of OPEs and HMs.

Comprehensive dietary exposure assessment of the Chinese population to organophosphate esters (OPEs): Results of the sixth China total diet study

Organophosphate esters (OPEs) are emerging pollutants, while data on their occurrence in foods and human dietary intake are limited. Based on the 6th China total diet study conducted in 2016-2019, this study implemented a comprehensive survey of OPEs in plant-derived foods of cereals, potatoes, legumes, fruits, vegetables, and further assessed dietary exposure from both plant- and animal-derived food. The sum concentrations of 15 OPEs in the plant-derived samples ranged from 0.567 to 106 ng/g ww. 2-Ethylhexyl diphenyl phosphate (EHDPP) (median: 1.14 ng/g ww) had the highest level in plant-derived foods, with a proportion of 35.6% in the total median OPEs. Regional distribution analysis showed a higher contamination of OPEs in plant-derived food from northern area of China. Estimated dietary intakes (EDIs) of ∑OPEs for Chinese population were from 109 ng/kg bw/day in Beijing to 1164 ng/kg bw/day in Gansu province, with mean and median of 296 and 222 ng/kg bw/day, respectively. Although animal-derived foods had higher levels of OPEs, plant-derived foods, specifically cereals, was the major source of dietary OPE intake. The EDIs were much lower than reference doses, which suggested the intakes of OPEs via food consumption could not cause significant health risks to the Chinese population at present.

Organophosphate esters and their metabolites in silver pomfret (Pampus argenteus) of the Vietnamese coastal areas: Spatial-temporal distribution and exposure risk

A large number of studies on organophosphate esters (tri-OPEs) in marine organisms have not assessed the simultaneous occurrence of tri-OPEs and their metabolites (di-OPEs) in these species. This research investigated the concentration and geographical distribution of 15 tri-OPEs and 7 di-OPEs in 172 samples of Pampus argenteus that were collected annually from 2021 to 2023 at three distinct locations along the Vietnamese coast. As a result, tri-OPEs and di-OPEs were detected in numerous fish samples, indicating their widespread spatial and temporal occurrence in marine fish and pointing out the importance of monitoring their levels. The tri-OPEs and di-OPEs ranged within 2.1-38.9 ng g-1 dry weight (dw) and 3.2-263.4 ng g-1 dw, respectively. The mean concentrations of tri-OPEs ranged from 0.4 (TIPrP) to 5.4 ng g-1 dw (TBOEP), with TBOEP and TEHP having the highest mean values. In addition, the profiles of tri-OPEs in fish exhibited a descending order: Σalkyl OPEs > ΣCl-alkyl OPEs > Σaryl OPEs. The di-OPEs, namely BEHP and DMP, had the highest mean levels, measuring 33.4 ng g-1 dw and 23.8 ng g-1 dw, respectively. Furthermore, there have been significant findings of strong positive correlations between di-OPEs and tri-OPE pairs (p < 0.05). It is worth noting that there is a noticeable difference in the composition of tri-OPEs between the North and other regions. Despite these findings, the presence of OPE-contaminated fish did not pose any health risks to Vietnam's coastal population.

Occurrence, spatial distribution and ecological risk assessment of Organophosphate Esters in surface water and sediments from the Ravi River and its tributaries

Organophosphate esters (OPEs) are widely used as substitutes for brominated flame retardants and characterized as emerging contaminants. Due to their toxicity and persistent nature, OPEs are becoming a matter of greater concern worldwide. However, information about the pollution profile of OPEs and associated ecological risks is still scarce in environmental matrices of the South Asian region, particularly Pakistan. Hence, the current study was conducted to investigate the occurrence, spatial distribution patterns, ecological risks and riverine flux of 10 organophosphate esters in surface water and sediments of Ravi River and its four tributaries. The concentrations of ∑10OPEs were in the range of 19.2 - 105 ng/L, with the dominance of chlorinated-OPEs (51 %) in surface water, whereas in case of sediments, the ∑10OPEs concentrations ranged from 20.7 to 149 ng/g dw, with high abundance of non - chlorinated alkyl-OPEs, which contributed about 56 % to total OPE concentration. The correlation analysis signified a strong positive relation of OPEs with TOC (p < 0.05, R = 0.76) in sediments; and in addition to this, field-based LogKoc values were estimated to be higher than predicted LogKoc. Moreover, a significantly positive correlation (p < 0.05, R = 0.88) was observed between LogKoc and LogKow, implying that hydrophobicity plays a significant role in OPE distribution in different environmental matrices. The global comparison revealed that contamination status of OPEs in the present study was comparatively lower than other regional findings, furthermore, principal component analysis suggested vehicular emissions, industrial discharges, household supplies and atmospheric deposition as main sources of OPEs occurrence in current study region. Furthermore, the riverine flux of ∑10OPEs was estimated to be 0.68 tons/yr and the ecological risk assessment indicated that all OPEs, except EHDPP and TCrP, showed negligible or insignificant ecological risks for aquatic organisms.

Nontarget Identification of Novel Organophosphorus Flame Retardants and Plasticizers in Indoor Air and Dust from Multiple Microenvironments in China

The indoor environment is a typical source for organophosphorus flame retardants and plasticizers (OPFRs), yet the source characteristics of OPFRs in different microenvironments remain less clear. This study collected 109 indoor air samples and 34 paired indoor dust samples from 4 typical microenvironments within a university in Tianjin, China, including the dormitory, office, library, and information center. 29 target OPFRs were analyzed, and novel organophosphorus compounds (NOPs) were identified by fragment-based nontarget analysis. Target OPFRs exhibited the highest air and dust concentrations of 46.2-234 ng/m3 and 20.4-76.0 μg/g, respectively, in the information center, where chlorinated OPFRs were dominant. Triphenyl phosphate (TPHP) was the primary OPFR in office air, while tris(2-chloroethyl) phosphate dominated in the dust. TPHP was predominant in the library. Triethyl phosphate (TEP) was ubiquitous in the dormitory, and tris(2-butoxyethyl) phosphate was particularly high in the dust. 9 of 25 NOPs were identified for the first time, mainly from the information center and office, such as bis(chloropropyl) 2,3-dichloropropyl phosphate. Diphenyl phosphinic acid, two hydroxylated and methylated metabolites of tris(2,4-ditert-butylphenyl) phosphite (AO168), and a dimer phosphate were newly reported in the indoor environment. NOPs were widely associated with target OPFRs, and their human exposure risk and environmental behaviors warrant further study.

Occurrence, potential sources, and ecological risks of traditional and novel organophosphate esters in facility agriculture soils: A case study in Beijing, China

Although traditional organophosphate esters (OPEs) in soils have attracted widespread interest, there is little information on novel OPEs (NOPEs), especially in facility agriculture soils. In this work, we surveyed 11 traditional OPEs, four NOPEs, and four corresponding organophosphite antioxidant precursors (OPAs) for the NOPEs in soil samples collected from facility greenhouses and open fields. The median summed concentrations of traditional OPEs and NOPEs were 14.1 μg/kg (range: 5.38-115 μg/kg) and 702 μg/kg (range: 348-1952 μg/kg), respectively, in film-mulched soils from greenhouses. These concentrations were much higher than those in soils without mulch films, which suggests that OPEs in soils are associated with plastic mulch films. Tris(2,4-di-tert-butylphenyl) phosphate, which is a NOPE produced by oxidation of (2,4-di-tert-butylphenyl) phosphite, was the predominant congener in farmland soils, with concentrations several orders of magnitude greater than those of traditional OPEs. Comparisons of OPEs in different mulch films and the corresponding mulched soils revealed that degradable and black films caused more severe pollution than polyethylene and white films. Traditional OPEs, including tris(2-ethylhexyl) phosphate and tricresyl phosphate, exhibited moderate risks in farmland soils, especially in film-mulched soils. NOPEs, including trisnonylphenol phosphate, posed high ecological risks to the terrestrial ecosystem. Risk evaluations should be conducted for a broad range of NOPEs in the environment.

Pollution characteristics and risk assessment of organophosphate esters (OPEs) in typical industrial parks in Southwest China

As alternative substances of PBDEs, organophosphate esters (OPEs), an emerging organic pollutant, were increasingly produced and used in many kinds of industries and consumer products. However, OPEs also have various adverse toxic effects. Information on the pollution levels and exposure to OPEs in related industries is still limited. This study presented data on OPE contamination in the soil, leaf, and river water samples from seven typical industrial parks in Southwest China. Total concentration of seven OPEs (Σ7OPE) including tri-n-butyl phosphate (TnBP), tris-(2-ethylhexyl) phosphate (TEHP), tris-(2-butoxyethyl) phosphate (TBEP), tris-(2-carboxyethyl) phosphine (TCEP), triphenyl phosphate (TPhP), tris-(1,3-dichloro-2-propyl) ester (TDCPP), and tris-(chlorisopropyl) phosphate (TCPP) in the soil samples (36.2 ~ 219.7 ng/g) and the surrounding river water samples (118.9 ~ 287.7 ng/L) were mostly lower than those in other studies, while the Σ7OPE level in the leaves (2053.3 ~ 8152.7 ng/g) was relatively high. There were significant differences in the concentration and distribution of OPEs in the surrounding environment of different industrial parks. TDCPP, TnBP, and TCPP could be used as the characteristic compound in soil samples from auto industrial park, river samples from shoe making industrial park, and leaf samples from logistics park, respectively. The parameter m (the content ratio of chlorinated OPEs to alkyl OPEs) was suggested to distinguish the types of industrial park preliminary. When m ≥ 1, it mainly refers to heavy industries sources such as automobiles, electronics, and machinery, etc. When m<1, it mainly for the light industrial sources such as textile industry, transportation services, and resources processing, etc. For logistics park, furniture park and Wuhou comprehensive industrial park, the volatilization of materials was the main sources of OPEs in the surrounding environment, while more effort was required to strengthen the pollution control and management of the waste water and soil in the pharmacy industrial park, shoe making industrial park and auto industrial park. Risk assessment showed that there was a negligible non-cancer and carcinogenic risk in the soil, while high attention should be paid to the non-cancer risk for children.

Occurrence of organophosphorus flame retardants in Xiangjiang River: Spatiotemporal variations, potential affecting factors, and source apportionment

The environmental occurrence of organophosphorus flame retardants (OPFRs) is receiving increasing attention. However, their distribution in the Xiangjiang River, an important tributary in the middle reaches of the Yangtze River, is still uncharacterized, and the potential factors influencing their distribution have not been adequately surveyed. In this study, the occurrence of OPFRs in the Xiangjiang River was comprehensively investigated from upstream to downstream seasonally. Fourteen OPFRs were detected in the sampling area, with a total concentration (∑OPFRs) ranging from 3.16 to 462 ng/L, among which tris(1-chloro-2-propyl) phosphate was identified as the primary pollutant (ND - 379 ng/L). Specifically, ∑OPFRs were significantly lower in the wet season than in the dry season, which may be due to the dilution effect of river flow and enhanced volatilization caused by higher water temperatures. Additionally, Changsha (during the dry season) and Zhuzhou (during the wet season) exhibited higher pollution levels than other cities. According to the Redundancy analysis, water quality parameters accounted for 35.7% of the variation in the occurrence of OPFRs, in which temperature, ammonia nitrogen content, dissolved oxygen, and chemical oxygen demand were identified as the potential influencing factors, accounting for 28.1%, 27.2%, 24.1%, and 11.5% of the total variation, respectively. The results of the Positive Matrix Factorization analysis revealed that transport and industrial emissions were the major sources of OPFRs in Xiangjiang River. In addition, there were no high-ecological risk cases for any individual OPFRs, although tris(2-ethylhexyl) phosphate and tributoxyethyl phosphate presented a low-to-medium risk level. And the results of mixture risk quotients indicated that medium-risk sites were concentrated in the Chang-Zhu-Tan region. This study enriches the global data of OPFRs pollution and contributes to the scientific management and control of pollution.

Organophosphate esters in water and air: A minireview of their sources, occurrence, and air-water exchange

Organophosphate esters (OPEs) have received considerable attention in environmental research due to their extensive production, wide-ranging applications, prevalent presence, potential for bioaccumulation, and associated ecological and health concerns. Low efficiency of OPE removal results in the effluents of wastewater treatment plants emerging as a significant contributor to OPE contamination. Their notable solubility and mobility give OPEs the potential to be transported to coastal ecosystems via river discharge and atmospheric deposition. Previous research has indicated that OPEs have been widely detected in the atmosphere and water bodies. Atmospheric deposition across air-water exchange is the main input route for OPEs into the environment and ecosystems. The main processes that contribute to air-water exchange is air-water diffusion, dry deposition, wet deposition, and the air-water volatilization process. The present minireview links together the source, occurrence, and exchange of OPEs in water and air, integrates the occurrence and profile data, and summarizes their air-water exchange in the environment.

Relationship between flame retardants and respiratory health- A systematic review and meta-analysis of observational studies

Chronic respiratory diseases are a dealing cause of death and disability worldwide. Their prevalence is steadily increasing and the exposure to environmental contaminants, including Flame Retardants (FRs), is being considered as a possible risk factor. Despite the widespread and continuous exposure to FRs, the role of these contaminants in chronic respiratory diseases is yet not clear. This study aims to systematically review the association between the exposure to FRs and chronic respiratory diseases. Searches were performed using the Cochrane Library, MEDLINE, EMBASE, PUBMED, SCOPUS, ISI Web of Science (Science and Social Science Index), WHO Global Health Library and CINAHL EBSCO. Among the initial 353 articles found, only 9 fulfilled the inclusion criteria and were included. No statistically significant increase in the risk for chronic respiratory diseases with exposure to FRs was found and therefore there is not enough evidence to support that FRs pose a significantly higher risk for the development or worsening of respiratory diseases. However, a non-significant trend for potential hazard was found for asthma and rhinitis/rhinoconjunctivitis, particularly considering urinary organophosphate esters (OPEs) including TNBP, TPHP, TCEP and TCIPP congeners/compounds. Most studies showed a predominance of moderate risk of bias, therefore the global strength of the evidence is low. The limitations of the studies here reviewed, and the potential hazardous effects herein identified highlights the need for good quality large-scale cohort studies in which biomarkers of exposure should be quantified in biological samples.

Occurrence, distribution, sources, and risk assessment of organophosphate esters in typical coastal aquaculture waters of China

This study monitored 20 organophosphate esters (OPEs) in water and sediment from three typical mariculture bases (Yunxi Marine Ranching (YX), Hangzhou Bay (HZB), and Zhelin Bay (ZLB)) and Meiliang Bay (MLB) of Taihu Lake in China, focusing on the spatial distribution and sources of OPEs. Moreover, the occurrence and risk of OPEs in fishes from ZLB were evaluated. The ∑OPE concentrations in waters followed the order MLB (591 ng/L) > YX (102 ng/L) > HZB (70.0 ng/L) > ZLB (37.4 ng/L), with tri(1-chloro-2-propyl) phosphate (TCIPP), triethyl phosphate (TEP), and tri(2-chloroethyl) phosphate (TCEP) being the dominant OPEs. Significantly higher ∑OPE concentrations were found in sediment in MLB compared to the other three areas with similar levels. The decreasing concentrations of OPEs from nearshore to offshore areas in HZB and MLB indicated that terrigenous input is the main source of OPEs. The even distribution of OPEs in YX and ZLB combined with PCA analysis suggested ship traffic or aquaculture activities are also potential sources. The ∑OPE concentrations in fishes ranged from 0.551-2.45 ng/g wet weight, with TCIPP, tri-phenyl phosphate (TPHP), and TCEP being the main OPEs. Hydrophobicity was a key factor affecting the sediment-water distribution coefficients and the bioaccumulation factors of OPEs. The human exposure to OPEs through consumption of fishes from ZLB had a low health risk.

Influence of watershed characteristics and human activities on the occurrence of organophosphate esters related to dissolved organic matter in estuarine surface water

Organophosphate esters (OPEs) are widespread in aquatic environments and pose potential threats to ecosystem and human health. Here, we profiled OPEs in surface water samples of heavily urbanized estuaries in eastern China and investigated the influence of watershed characteristics and human activities on the spatial distribution of OPEs related to dissolved organic matter (DOM). The total OPE concentration ranged from 22.3 to 1201 ng/L, with a mean of 162.6 ± 179.8 ng/L. Chlorinated OPEs were the predominant contaminant group, accounting for 27.4-99.6 % of the total OPE concentration. Tris(2-chloroisopropyl) phosphate, tris(1,3-dichloro-2-propyl) phosphate, and tributyl phosphate were the dominant compounds, with mean concentrations of 111.2 ± 176.0 ng/L, 22.6 ± 21.5 ng/L, and 14.8 ± 14.9 ng/L, respectively. Variable OPE levels were observed in various functional areas, with significantly higher concentrations in industrial areas than in other areas. Potential source analysis revealed that sewage treatment plant effluents and industrial activities were the primary OPE sources. The total OPE concentrations were negatively correlated to the mean slope, plan curvature, and elevation, indicating that watershed characteristics play a role in the occurrence of OPEs. Individual OPEs (triisobutyl phosphate, tris(2-butoxyethyl) phosphate, tris(2-chloroethyl) phosphate, and tricresyl phosphate) and Σalkyl-OPEs were positively correlated to the night light index or population density, suggesting a significant contribution of human activity to OPE pollution. The co-occurrence of OPEs and DOM was also observed, and the fluorescence indices of DOM were found to be possible indicators for tracing OPEs. These findings can elucidate the potential OPE dynamics in response to DOM in urbanized estuarine water environments with intensive human activities.