Occurrence, seasonal variation, potential sources, and risks of organophosphate esters in a cold rural area in Northeast 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.

Underlying mechanisms of metabolic dysfunction-associated steatotic liver disease induced by 2-ethylhexyl diphenyl phosphate and its hydroxylated metabolite in zebrafish (Danio rerio)

2-Ethylhexyl diphenyl phosphate (EHDPHP) is ubiquitous in various environmental media and organisms. Due to its susceptibility to biotransformation, its primary product 2-ethyl-5-hydroxyhexyl diphenyl phosphate (5-OH-EHDPHP) is almost at equal level in organisms. However, their hepatotoxicity remains unclear. In this study, adult zebrafish were exposed to 5, 35, or 245 µg/L of EHDPHP for 28 days. Distinct metabolic dysfunction-associated steatotic liver disease (MASLD) was observed in treated zebrafish, indicated by increased hepatic lipid levels (total cholesterol, triglycerides, nonesterified fatty acids, and fat droplets), steatosis (hepatic ballooning), and inflammation (tnf-α and il-6). Combined the in vitro hepatic cell test, molecular docking and molecular dynamics simulation, it was revealed that peroxisome proliferator-activated receptor gamma (pparγ) was upregulated upon EHDPHP exposure, thereby facilitating lipid synthesis and hepatic lipid accumulation. Notably, its main metabolite 5-OH-EHDPHP induced stronger hepatocyte toxicity and PPARγ transcription. Additionally, serious liver function damage was observed, with aspartate aminotransferase, alanine transaminase, albumin, and γ-glutamyl transferase levels markedly disrupted. This increases the risk of development of cardiovascular disease, hepatic cirrhosis or other chronic conditions. Collectively, the results demonstrate that EHDPHP may cause strong hepatic toxicities, which may be pounded by its hydroxylated metabolites.

Identification and spatial distribution of organophosphorus flame retardants in surface soils from typical petrochemical industry and flame retardant production parks in China

Organophosphorus flame retardants (OPFRs) are widely used as flame retardants and plasticizers in various industries. As for the petrochemical industry, many petrochemical products such as lubricant base oil, gasoline, etc., require the use of OPFRs in their production processes. However, the emission characteristics of OPFRs from the petrochemical industry are limited. Thus, this study investigated the OPFR characteristics from three petrochemical industry parks, as well as one flame-retardant manufacturing park. There were 196 samples collected and thirteen OPFRs were analyzed. The median OPFR concentrations were 5.29-12.3 and 2.62 ng/g in three petrochemical industry parks and the flame-retardant manufacturing park, respectively. The OPFR compositions differed between petrochemical industry parks and flame-retardant production park. Chlorinated-OPFRs (especially TCIPP) accounting for ≥64.2% of the composition of soil OPFRs and alkyl-OPFRs (80.5%) were the respective predominant congeners in the petrochemical industry parks and the flame-retardant manufacturing park. Spatial distribution analysis revealed OPFR pollution within the park's vicinity, extending toward the surrounding areas. Principal component analysis further revealed that OPFRs primarily originated from industrial emissions, polyurethane foam use, and oil-related emissions for the petrochemical industry parks. However, high concentrations were also found in residential areas, farmlands, and populated areas from the flame-retardant manufacturing park and surrounding areas, indicating other potential sources. Summarily, this study provided insight into the contamination characteristics of OPFRs from typical industrial parks and their surroundings.

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.

Source identification and human exposure assessment of organophosphate flame retardants and plasticisers in soil and outdoor dust from Nigerian e-waste dismantling and dumpsites

Electronic waste (e-waste) dismantling and dumpsite processes are major sources of organophosphate flame retardant and plasticiser emissions and may pose potentially adverse effects on environment and human health. In 20 outdoor dust and 49 soil samples collected from four e-waste dismantling and three e-waste dumpsites in two States of Nigeria (Lagos and Ogun), we identified 13 alternative plasticisers (APs), 7 legacy phthalate plasticisers (LPs), and 17 organophosphorus flame retardants (OPFRs) for the first time in African e-waste streams. In the samples from dismantling sites, the range (median) concentrations of ∑13APs, ∑7LPs, and ∑17OPFRs were 11-2747 μg/g (144 μg/g), 11-396 μg/g (125 μg/g), and 0.2-68 μg/g (5.5 μg), in dust respectively and 1.8-297 μg/g (55 μg/g), 1.3-274 μg/g (48.5 μg/g), and 1.6-62 μg/g (1.6 μg/g), in soil respectively. Results for soil samples from e-waste dumpsites were (6.6-195 μg/g (23.7 μg/g), 6.0-295 μg/g (54.8), and 0.4-42.3 μg/g (9.0 μg/g) for ∑13APs, ∑7LPs, and ∑17OPFRs respectively. Overall, concentrations of APs were significantly higher at the dismantling sites (p = 0.005) compared to dumpsites, levels of LPs were higher at dismantling sites but not significant, while OPFR concentrations were significantly higher in dumpsite samples (p = 0.005). Plasticisers were found to be major contributors to pollution at e-waste dismantling sites, while OPFRs were associated with both automobile dismantling and e-waste dumpsite processes. Following particle size fractionation of selected soil samples, higher concentrations of targeted compounds were observed in the smaller mesh (180 μm) soil sieve fraction. For dust, the total median estimated daily intake via ingestion and dermal adsorption (EDIing and EDIderm) ranged from 43 to 74 ng/kg bw/day and 0.4-0.7 ng/kg bw/day, respectively. Correspondingly, 4.6-45 ng/kg bw/day and 0.015-0.57 ng/kg bw/day were the values found for soil, respectively. According to these results, the targeted chemicals do not appear to pose a non-carcinogenic risk to e-waste workers through ingestion or dermal contact of bio-accessible fractions of the chemicals. Human biomonitoring campaigns are recommended in the Nigerian e-waste environment considering the elevated concentration levels found for the majority of targeted compounds and that risk parameters required for exposure assessment were only available for a limited number of compounds.

Construction and validation of a risk prediction model for soldiers with frostbite in northeast China: a cross-sectional study

BACKGROUND

One of the challenges of physical training in extreme condition is frostbite, especially in Northeast China. In this study, we aimed to construct a risk prediction model for frostbite among soldiers in Northeast China, and verify its effect.

METHODS

698 participants were selected via convenience sampling from Northeast China from December 2021 to January 2022 (winter). They were randomly divided into a training set (N = 479) and a testing set (N = 202) in a ratio of 7:3. All participants completed a researcher-made questionnaire on frostbite. The prediction model was constructed through the use of Logistic regression analysis, which was used to predict the independent risk factors for frostbite formation and screen significant indicators. The model's performance was assessed using the receiver operating characteristic (ROC) curve and decision curve analysis (DCA) to evaluate the prediction efficiency and goodness of fit.

RESULTS

The incidence of frostbite in the training set was 19.83% (95 people), all of which were first-degree frostbite. Among them, frostbite in multiple parts was the most common (58.95%), followed by singular body parts like hands (24.21%), ears (11.58%) and feet (5.26%). Single factor logistic regression analyses showed that ambient temperature, ambient wind speed, outdoor stationary time, stationary status, and history of frostbite are independent risk factors that affect the occurrence of frostbite. Furthermore, we constructed the frostbite risk prediction model for soldiers in the northeastern region of China. The area under the receiver operating characteristic curve (AUC) for the risk of frostbite in the training set and testing set was 0.816 (95% CI, 0.770 ~ 0.862) and 0.787 (95% CI, 0.713 ~ 0.860), respectively. The Hosmer-Lemeshow test of the model showed χ2 = 11.328 and P = 0.184 (> 0.05). The DCA curve indicated that most of the clinical net benefits of the model are greater than 0, demonstrating good clinical usefulness.

CONCLUSION

The constructed frostbite prediction model can effectively identify soldiers with a higher risk of frostbite. It provided theoretical support for commanders to take preventive measures to reduce the incidence of frostbite among soldiers and was of great clinical guiding significance.

Contamination Status of Novel Organophosphate Esters Derived from Organophosphite Antioxidants in Soil and the Effects on Soil Bacterial Communities

The contamination status of novel organophosphate esters (NOPEs) and their precursors organophosphite antioxidants (OPAs) and hydroxylated/diester transformation products (OH-OPEs/di-OPEs) in soils across a large-scale area in China were investigated. The total concentrations of the three test NOPEs in soil were 82.4-716 ng g-1, which were considerably higher than those of traditional OPEs (4.50-430 ng g-1), OPAs (n.d.-30.8 ng g-1), OH-OPEs (n.d.-0.49 ng g-1), and di-OPEs (0.57-21.1 ng g-1). One NOPE compound, i.e., tris(2,4-di-tert-butylphenyl) phosphate (AO168 = O) contributed over 65% of the concentrations of the studied OPE-associated contaminants. A 30-day soil incubation experiment was performed to confirm the influence of AO168 = O on soil bacterial communities. Specific genera belonging to Proteobacteria, such as Lysobacter and Ensifer, were enriched in AO168 = O-contaminated soils. Moreover, the ecological function of methylotrophy was observed to be significantly enhanced (t-test, p < 0.01) in soil treated with AO168 = O, while nitrogen fixation was significantly inhibited (t-test, p < 0.01). These findings comprehensively revealed the contamination status of OPE-associated contaminants in the soil environment and provided the first evidence of the effects of NOPEs on soil microbial communities.

Distribution patterns and origins of organophosphate esters in soils from different climate systems on the Tibetan Plateau

Organophosphate esters (OPEs) are extensively applied in various materials as flame retardants and plasticizers, and have high biological toxicity. OPEs are detected worldwide, even in distant polar regions and the Tibetan Plateau (TP). However, few studies have been performed to evaluate the distribution patterns and origins of OPEs in different climate systems on the TP. This study investigated the distribution characteristics, possible sources, and ecological risks of OPEs in soils from the different climate systems on the TP and its surroundings. The total concentrations of OPEs in soil varied from 468 to 17,451 pg g-1 dry weight, with greater concentrations in southeast Tibet (monsoon zone), followed by Qinghai (transition zone) and, finally, southern Xingjiang (westerly zone). OPE composition profiles also differed among the three areas with tri-n-butyl phosphate dominant in the westerly zone and tris(2-butoxyethyl) phosphate dominant in the Indian monsoon zone. Correlations between different compounds and altitude, soil organic carbon, or longitude varied in different climate zones, indicating that OPE distribution originates from both long-range atmospheric transport and local emissions. Ecological risk assessment showed that tris(2-chloroethyl) phosphate and tri-phenyl phosphate exhibited medium risks in soil at several sites in southeast Tibet. Considering the sensitivity and vulnerability of TP ecosystems to anthropogenic pollutants, the ecological risks potentially caused by OPEs in this region should be further assessed.

Tris(2-ethylhexyl) phosphate induces cytotoxicity in TM3 Leydig cells by modulating autophagy and endoplasmic reticulum stress

Tris (2-ethylhexyl) phosphate (TEHP) is a frequently used organophosphorus flame retardant with significant ecotoxicity and widespread human exposure. Recent research indicates that TEHP has reproductive toxicity. However, the precise cell mechanism is not enough understood. Here, by using testicular mesenchymal stromal TM3 cells as a model, we reveal that TEHP induces apoptosis. Then RNA sequencing analysis, immunofluorescence, and western blotting results show that THEP inhibits autophagy flux and enhances endoplasmic reticulum (ER) stress. Moreover, the activation of the ER stress is critical for TEHP-induced cell injury. Interestingly, TEHP-induced ER stress is contributed to autophagic flux inhibition. Furthermore, pharmacological inhibition of autophagy aggravates, and activation of autophagy attenuates TEHP-induced apoptosis. In summary, these findings indicate that TEHP triggers apoptosis in mouse TM3 cells through ER stress activation and autophagy flux inhibition, offering a new perspective on the mechanisms underlying TEHP-induced interstitial cytotoxicity in the mouse testis.

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.

Co-occurrence of organophosphate esters and phosphorus fractions in river sediments: Implications for pollution prediction and environment risk assessment

Organophosphate esters (OPEs) and phosphorus (P) are widespread pollutants in aquatic ecosystems, presenting potential ecological risks. However, there is still a lack of comprehensive understanding of their relationships in sediments. In this study, we investigated the co-occurrence and behaviors of the OPEs and P in urban river sediments. The results indicated serious OPE and P pollution in the study area, with substantial spatial variations in the contents and compositions. The OPE congeners and P fractions exhibited different correlations, particularly more significant linear relationships (R = 0.455 - 0.816, p < 0.05) were observed between the aryl-OPEs and P fractions, potentially due to the influence from sources, physicochemical properties, and total organic carbon. About 56 to 71% of variability in predicting the concentrations of aryl-OPE can be explained by the multiple linear regression model using the Fe/Al- and Ca-bound P contents. The study regions exhibited greater aryl-OPEs ecological risks were consistent with the regions with more serious Total P pollution levels. This study represents the first report demonstrating the potential of Fe/Al-P and Ca-P contents in predicting aryl-OPE contents in heavily polluted sediments, providing a useful reference to comprehensively assess the occurrence and environmental behaviors of aryl-OPEs in anthropogenic polluted sediments.

Occurrence, distribution, potential sources, and risks of organophosphate esters in fresh snow on Urumqi Glacier No. 1, eastern Tien Shan, China

Organophosphate esters (OPEs), extensively used as flame retardants, are widely detected in various regions and environments. The potential toxicity of OPEs has caused great concern in recent years. Based on the global distillation model, the Tien Shan glaciers, such as Urumqi Glacier No. 1, could be as a potential "sink" for OPEs. However, little is known about the concentration, distribution, potential sources, and ecological risks of OPEs in Tien Shan glaciers. In this study, fresh snow samples were collected at various altitudes on the Urumqi Glacier No. 1, eastern Tien Shan, China. The total concentrations of ten OPEs (Σ10OPEs) ranged from 116 to 152 ng/L. The most abundant OPE was tris-(2-chloroisopropyl) phosphate (TCIPP), contributing to 74 % of the total OPEs. Σ10OPEs, tri-n-butyl phosphate (TnBP), and TCIPP concentrations showed positive correlations with altitude, indicating the effect of cold condensation on OPEs deposition. Based on air mass back-trajectory analysis and principal component analysis, we found that emissions from both traffic and household products in indoor environment were the important sources, and OPEs on the Urumqi Glacier No. 1 might mainly originate from Europe. Our assessment also showed triphenyl phosphate (TPhP) posed a low ecological risk in snow. This is the first systematic study of OPEs on the Tien Shan glaciers.

Occurrence, source apportionment, and ecological risk assessment of organophosphate esters in surface sediment from the Ogun and Osun Rivers, Southwest Nigeria

Organophosphate esters (OPEs) are synthetic chemicals widely used as e.g., flame retardants and plasticisers in various consumer products. Due to the toxicity of OPEs in aquatic ecosystems, exposure of fauna and flora to these compounds is of potential concern. In this study, the concentrations, profiles, sources, and ecological risk of eight OPEs were investigated in the sediments from the two major rivers in southwest Nigeria. Concentrations of ∑OPEs in surface sediments were in the range 13.1 - 2110 ng/g dry weight (dw) (median: 378 ng/g dw) in the Ogun River and 24.7-589 ng/g dw (median: 174 ng/g dw) in the Osun River. These concentrations are broadly within the range of those reported in surface sediment in previous studies conducted in other locations around the world. Tris (2-butoxyethyl) phosphate (TBOEP) was the dominant OPE in the sediment samples with a median concentration of 337 and 126 ng/g dw for the Ogun and Osun Rivers respectively, while tri-n-butyl phosphate (TnBP) was not detected in any sample. Excluding TBOEP, the chlorinated organophosphate esters: tris(2-chloroethyl) phosphate (TCEP), tris(2-chloro-propyl) phosphate (TCIPP), and tris(1,3-dichloro-2-propyl) phosphate (TDCIPP) were the dominant OPEs in the Osun River, while the aryl-OPEs: triphenyl phosphate (TPHP), 2-ethylhexyl diphenyl phosphate (EHDPP), and tri-m-tolyl phosphate (TMTP) were dominant in the Ogun River. Under a median exposure scenario, moderate ecological risk was predicted from exposure to TCIPP in the Osun River. In contrast, under a high exposure scenario, concentrations of TDCIPP (risk quotient, RQ = 5.33-5.37) constituted a high ecological risk in both rivers, with moderate risks observed for TBOEP (RQ = 0.022-0.18) and TCIPP (RQ = 0.097 - 0.16). Therefore, the risk to aquatic organisms from concomitant exposure to mixtures of OPEs in freshwater ecosystems requires further investigation.

Comprehensive analysis of the fates and risks of veterinary antibiotics in a small ecosystem comprising a pig farm and its surroundings in Northeast China

This study investigated the behavior of veterinary antibiotics (VAs) in a small farm ecosystem. Manure and environmental samples were collected around a large pig farm in northeast China. Thirty-four VAs in six categories were analyzed. Then, a multimedia fugacity model was used to estimate the fates of VAs in the environment. The results showed that VAs were prevalent in manure, soil, water, and sediment, but not in crops. Compared with fresh manure, VA levels were significantly lower in surface manure piles left in the open air for 3-6 months. The main VAs, tetracyclines and quinolones, decreased by 427.12 and 158.45 µg/kg, respectively. VAs from manure piles were transported to the surroundings and migrated vertically into deep soil. The concentrations of ∑VAs detected in agricultural soils were 0.03-4.60 µg/kg; > 94% of the mass inventory of the VAs was retained in soil organic matter (SOM), suggesting that SOM is the main reservoir for antibiotics in soil. Risk assessment and model analysis indicated that the negative impact of mixed antibiotics at low concentrations in farmland on crops may be mediated by indirect effects, rather than direct effects. Our findings highlight the environmental fates and risks of antibiotics from livestock farms.

First Insight into the Formation of In Vivo Transformation Products of 2-Ethylhexyl diphenyl phosphate in Zebrafish and Prediction of Their Potential Toxicities

As a frequently detected organophosphorus flame retardant in the environment, 2-ethylhexyl diphenyl phosphate (EHDPHP) is vulnerable to biotransformation, while the transformation mechanisms and potential toxicities of its transformation products remain unclear. In the present study, in vivo transformation products of EHDPHP in exposed zebrafish for 21d were analyzed by suspect screening and identified by mass spectrometry. Fifteen metabolites were identified, including 10 phase I and 5 phase II products with monohydroxylated products being primary, among which 5-OH-EHDPHP was the most predominant. Two sulfation products and one terminal desaturation metabolite of EHDPHP were reported for the first time. A density functional calculation coupled with molecular docking disclosed that the specific conformation of EHDPHP docked in the protein pockets favored the primary formation of 5-OH-EHDPHP, which was fortified to be a more suitable biomarker of EHDPHP exposure. The in vitro tests suggested that EHDPHP transformation took place not only in liver but also in intestine, where gut microbes played an important role. Due to lack of standards, in silico toxicity prediction combined with molecular docking indicated that several metabolites potentially cause higher toxicities than EHDPHP. The results provide deep insight into the potential health risks due to specific in vivo transformation of EHDPHP.

Non-target screening and risk assessment of organophosphate esters (OPEs) in drinking water resource water, surface water, groundwater, and seawater

By use of an integrated target, suspect, and non-target screening strategy, we investigated occurrence and spatial distribution of organophosphate esters (OPEs) in four types of water (drinking water resource water, surface water, groundwater, and seawater) collected from Jiangsu Province (China) in 2021 (n = 111). Eighteen out of 23 target OPEs were detectable at least once in these analyzed samples, and the total concentrations (Σ18OPEs) of OPEs in various water samples exhibited a descending order following as: groundwater (67026 ng/L) > surface water (35803 ng/L) > drinking water resource water (21055 ng/L) > seawater (17820 ng/L). The highest concentration detected in groundwater may be ascribed to pollution from surrounding factories. Among the target OPEs, triethyl phosphate (TEP), tris(chloroethyl) phosphate (TCEP), and tris (1-chloro-2-propyl) phosphate (TCIPP) were the most abundant congeners with the average concentrations of 407 ng/L, 143 ng/L, and 475 ng/L, respectively. Besides of 18 target OPEs, we further identified 17 suspect OPEs (3 of them were fully identified by authentic standards) on the basis of in-house suspect screening OPE database, and 2 non-target organophosphates (OPs) on the basis of feature fragments. One of these 2 non-target OPs was fully identified as bis(2-chloroethyl) 2-chloroethylphosphonate (B2CE2CEPP) by matching the retention time and MS/MS data with authentic standard, and the other one was preliminarily identified as 2,4,8,10-tetra-tert-butyl-6-methoxydibenzo[d,f][1,3,2]dioxaphosphepin-6-one (TTBMDBDOPPO). We also observed that B2CE2CEPP shared a similar structure with TCEP, suggesting that they may have similar toxicological characteristics and commercial sources. The ecological and human health risk assessments indicated that all OPEs posed a low or negligible ecological risk to aquatic organisms (algae, crustacean, and fish), and negligible risk to human health except for trimethyl phosphate (TMP) in drinking water resource water.