Organophosphate (OP) diesters and a review of sources, chemical properties, environmental occurrence, adverse effects, and future directions

Uptake, translocation, and metabolism of organophosphate esters (OPEs) in plants and health perspective for human: A review

Plant uptake, accumulation, and transformation of organophosphate esters (OPEs) play vital roles in their geochemical cycles and exposure risks. Here we reviewed the recent research advances in OPEs in plants. The mean OPE concentrations based on dry/wet/lipid weight varied in 4.80-3,620/0.287-26.8/12,000-315,000 ng g-1 in field plants, and generally showed positive correlations with those in plant habitats. OPEs with short-chain substituents and high hydrophilicity, particularly the commonly used chlorinated OPEs, showed dominance in most plant samples, whereas some tree barks, fruits, seeds, and roots demonstrated dominance of hydrophobic OPEs. Both hydrophilic and hydrophobic OPEs can enter plants via root and foliar uptake, and the former pathway is mainly passively mediated by various membrane proteins. After entry, different OPEs undergo diverse subcellular distributions and acropetal/basipetal/intergenerational translocations, depending on their physicochemical properties. Hydrophilic OPEs mainly exist in cell sap and show strong transferability, hydrophobic OPEs demonstrate dominant distributions in cell wall and limited migrations owing to the interception of Casparian strips and cell wall. Additionally, plant species, transpiration capacity, growth stages, commensal microorganisms, and habitats also affect OPE uptake and transfer in plants. OPE metabolites derived from various Phase I transformations and Phase II conjugations are increasingly identified in plants, and hydrolysis and hydroxylation are the most common metabolic processes. The metabolisms and products of OPEs are closely associated with their structures and degradation resistance and plant species. In contrast, plant-derived food consumption contributes considerably to the total dietary intakes of OPEs by human, particularly the cereals, and merits specifical attention. Based on the current research limitations, we proposed the research perspectives regarding OPEs in plants, with the emphases on their behavior and fate in field plants, interactions with plant-related microorganisms, multiple uptake pathways and mechanisms, and comprehensive screening analysis and risk evaluation.

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.

Prenatal exposure to a mixture of organophosphate flame retardants and infant neurodevelopment: A prospective cohort study in Shandong, China

BACKGROUND

Previous studies have suggested that prenatal exposure to organophosphate flame retardants (OPFRs) may have adverse effect on early neurodevelopment, but limited data are available in China, and the overall effects of OPFRs mixture are still unclear.

OBJECTIVE

This study aimed to investigate the association between prenatal exposure to OPFR metabolites mixture and the neurodevelopment of 1-year-old infants.

METHODS

A total of 270 mother-infant pairs were recruited from the Laizhou Wan (Bay) Birth Cohort in China. Ten OPFR metabolites were measured in maternal urine. Neurodevelopment of 1-year-old infants was assessed using the Gesell Developmental Schedules (GDS) and presented by the developmental quotient (DQ) score. Multivariate linear regression and weighted quantile sum (WQS) regression models were conducted to estimate the association of prenatal exposure to seven individual OPFR metabolites and their mixture with infant neurodevelopment.

RESULTS

The positive rates of seven OPFR metabolites in the urine of pregnant women were greater than 70% with the median concentration ranged within 0.13-3.53 μg/g creatinine. The multivariate linear regression model showed significant negative associations between bis (1-chloro-2-propyl) phosphate (BCIPP), din-butyl phosphate (DnBP), and total OPFR metabolites exposure and neurodevelopment in all infants. Results from the WQS model consistently revealed that the OPFR metabolites mixture was inversely associated with infant neurodevelopment. Each quartile increased in the seven OPFR metabolites mixture was associated with a 1.59 decrease (95% CI: 2.96, -0.21) in gross motor DQ scores, a 1.41 decrease (95% CI: 2.38, -0.43) in adaptive DQ scores, and a 1.08 decrease (95% CI: 2.15, -0.02) in social DQ scores, among which BCIPP, bis (1, 3-dichloro-2-propyl) phosphate (BDCIPP) and DnBP were the main contributors.

CONCLUSION

Prenatal exposure to a mixture of OPFRs was negatively associated with early infant neurodevelopment, particularly in gross motor, adaptive, and social domains.

Universal occurrence of organophosphate tri-esters and di-esters in marine sediments: Evidence from the Okinawa Trough in the East China Sea

Despite numerous data on organophosphate tri-esters (tri-OPEs) in the environment, literatures on organophosphate di-esters (di-OPEs) in field environment, especially marine sediments remain scarce. This study addresses this gap by analyzing 35 abyssal sediment samples from the middle Okinawa Trough in the East China Sea. A total of 25 tri-OPEs and 10 di-OPEs were determined, but 13 tri-OPEs and 2 di-OPEs were nondetectable in any of these sediment samples. The concentrations of ∑12tri-OPE and ∑8di-OPE were 0.108-32.2 ng/g (median 1.11 ng/g) and 0.548-15.0 ng/g (median 2.74 ng/g). Chlorinated (Cl) tri-OPEs were the dominant tri-esters, accounting for 47.5 % of total tri-OPEs on average, whereas chlorinated di-OPEs represented only 19.2 % of total di-OPEs. This discrepancy between the relatively higher percentage of Cl-tri-OPEs and lower abundance of Cl-di-OPEs may be ascribed to the stronger environmental persistence of chlorinated tri-OPEs. Source assessment suggested that di-OPEs were primarily originated from the degradation of tri-OPEs rather than industrial production. Long range waterborne transport facilitated by oceanic currents was an important input pathway for OPEs in sediments from the Okinawa Trough. These findings enhance the understanding of the sources and transport of OPEs in marine sediments, particularly in the Okinawa Trough.

Discovering Novel Organophosphorus Compounds in Wastewater Treatment Plant Effluents through Suspect Screening and Nontarget Analysis

Limited knowledge on the structure of emerging organophosphorus compounds (OPCs) hampers our comprehensive understanding of their environmental occurrence and potential risks. Through suspect and nontarget screening, combining data-dependent acquisition, data-independent acquisition, and parallel reaction monitoring modes, we identified 60 OPCs (17 traditional and 43 emerging compounds) in effluents of 14 wastewater treatment plants (WWTPs) in Beijing and Qinghai, China. These OPCs comprise 26 organophosphate triesters, 17 organophosphate diesters, 6 organophosphonates, 7 organothiophosphate esters, and 4 other OPCs. Notably, 14 suspect OPCs were newly identified in WWTP effluents, and 16 nontarget OPCs were newly discovered in environmental matrices. Specifically, the cyclic phosphonate, (5-ethyl-2-methyl-1,3,2-dioxaphosphorinan-5-yl)methyl dimethyl phosphonate P-oxide (PMMMPn), consistently appeared in all WWTP effluents, with semiquantitative concentrations ranging from 44.4 to 282 ng/L. Its analogue, di-PMMMPn, presented in 93% of wastewater samples. Compositional differences between the WWTP effluents of two cities were mainly attributed to emerging OPCs. Hazard and ecological risk assessment underscored the substantial contribution of chlorinated organophosphate esters and organothiophosphate esters to overall risks of OPCs in WWTP effluents. This study provides the most comprehensive OPC profiles in WWTP effluents to date, highlighting the need for further research on their occurrence, fate, and risks, particularly for chlorinated OPCs.

Organophosphate triesters and their diester degradation products in the atmosphere-A critical review

Organophosphate triesters (tri-OPEs) have found substantial use as plasticizers and flame retardants in commercial and industrial products. Despite upcoming potential restrictions on use of OPEs, widespread environmental contamination is likely for the foreseeable future. Organophosphate diesters (di-OPEs) are known biotic or abiotic degradation products of tri-OPEs. In addition, direct use of di-OPEs as commercial products also contributes to their presence in the atmosphere. We review the available data on contamination with tri-OPEs and di-OPEs in both indoor and outdoor air. Concentrations of tri-OPEs in indoor air exceed those in outdoor air. The widespread discovery of tri-OPE traces in polar regions and oceans is noteworthy and is evidence that they undergo long-range transport. There are only two studies on di-OPEs in outdoor air and no studies on di-OPEs in indoor air until now. Current research on di-OPEs in indoor and outdoor air is urgently needed, especially in countries with potentially high exposure to di-OPEs such as the UK and the US. Di-OPE concentrations are higher at e-waste dismantling areas than at surrounding area. We also summarise the methods employed for sampling and analysis of OPEs in the atmosphere and assess the relative contribution to atmospheric concentrations of di-OPEs made by environmental degradation of triesters, compared to the presence of diesters as by-products in commercial triester products. Finally, we identify shortcomings of current research and provide suggestions for future research.

Curcumin attenuates diphenyl phosphate-induced apoptosis in GC-2spd(ts) cells through activated autophagy via the Nrf2/P53 pathway

Diphenyl phosphate (DPhP) is one of the frequently used derivatives of aryl phosphate esters and is used as a plasticizer in industrial production. Like other plasticizers, DPhP is not chemically bound and can easily escape into the environment, thereby affecting human health. DPhP has been associated with developmental toxicity, reproductive toxicity, neurodevelopmental toxicity, and interference with thyroid homeostasis. However, understanding of the underlying mechanism of DPhP on the reproductive toxicity of GC-2spd(ts) cells remains limited. For the first time, we investigated the effect of DPhP on GC-2spd(ts) cell apoptosis. By decreasing nuclear factor erythroid-derived 2-related factor (Nrf2)/p53 signaling, DPhP inhibited autophagy and promoted apoptosis. DPhP reduced total antioxidant capacity and nuclear Nrf2 and its downstream target gene expression. In addition, we investigated the protective effects of Curcumin (Cur) against DPhP toxicity. Cur attenuated the DPhP-induced rise in p53 expression while increasing Nrf2 expression. Cur inhibited DPhP-induced apoptosis in GC-2spd(ts) cells by activating autophagy via Nrf2/p53 signaling. In conclusion, our study provides new insights into the reproductive toxicity hazards of DPhP and demonstrates that Cur is an important therapeutic agent for alleviating DPhP-induced reproductive toxicity by regulating Nrf2/p53 signaling.

Single injection by LC-ESI-MS/MS for simultaneous determination of organophosphate tri- and di-esters in plant tissue based on ultrasonic-assisted sequential extraction and single-step purification

A novel methodology based on ultrasonic-assisted sequential extraction, dispersive-SPE purification, and single-injection on liquid chromatography-tandem mass spectrometry (LC-MS/MS) is proposed, for the first time, to simultaneously measure 14 tri-OPEs and 9 di-OPEs in plant tissues. The samples were successively ultrasonicated with a mixture of hexane:dichloromethane (1:1, v/v) and 8% acetic acid in acetonitrile for extracting tri- and di-OPEs purified with graphitized carbon black and quantitated on LC-MS/MS at the same time. The recoveries of targeted tri- and di-OPEs in the matrix spike ranged from 66% to 120% and 71% to 110% respectively. The proposed method was validated by processing eight types of common vegetables including spinach (Spinacia oleracea L.), lettuce (Lactuca sativa), carrot (Daucus carota var. sativa Hoffm.), sweet potato (Solanum tuberosum L.), cucumber (Cucumis sativus L.), tomato (Solanum lycopersicum L.), green beans (Phaseolus vulgaris), and cowpeas (Vigna unguiculata), with the recoveries of surrogates ranging from 84% to 98%.

Unravelling bioaccumulation, depletion and metabolism of organophosphate triesters in laying hens: Insight of in vivo biotransformation assisted by diester metabolites

Organophosphate triesters (tri-OPEs) threaten human health through dietary exposure, but little is known about their feed-to-food transfer and in vivo behavior in farm animals. Herein 135 laying hens were fed with contaminated feed (control group, low-level group and high-level group) to elucidate the bioaccumulation, distribution, and metabolism of the six most commonly reported tri-OPEs. The storage (breast muscle), metabolism and mobilization (liver and blood) and non-invasive (feather) tissues were collected. The exposure-increase (D1∼14) and depuration-decrease (D15∼42) trends indicated that feed exposure caused tri-OPE accumulation in animal tissues. Tissue-specific and moiety-specific behavior was observed for tri-OPEs. The highest transfer factor (TF) and transfer rate (TR) were observed in liver (TF: 14.8%∼82.3%; TR: 4.40%∼24.5%), followed by feather, breast muscle, and blood. Tris(2-chloroisopropyl) phosphate (TCIPP) had the longest half-life in feather (72.2 days), while triphenyl phosphate (TPhP) showed the shortest half-life in liver (0.41 days). Tri-OPEs' major metabolites (organophosphate diesters, di-OPEs) were simultaneously studied, which exhibited dose-dependent and time-dependent variations following administration. In breast muscle, the inclusion of di-OPEs resulted in TF increases of 735%, 1108%, 798%, and 286% than considering TCIPP, tributyl phosphate, tris(2-butoxyethyl) phosphate and tris(2-ethylhexyl) phosphate alone. Feather was more of a proxy of birds' long-term exposure to tri-OPEs, while short-term exposure was better reflected by di-OPEs. Both experimental and in silico modeling methods validated aryl-functional group facilitated the initial accumulation and metabolism of TPhP in the avian liver compared to other moiety-substituted tri-OPEs.

Co-occurrence of organophosphate diesters and organophosphate triesters in daily household products: Potential emission and possible human health risk

Eight paired organophosphate diesters (Di-OPs) and organophosphate triesters (Tri-OPs) were investigated in wipes from analytical instruments and 47 material samples related to household products, including textiles, electrical/electronic devices, building/ decoration materials and children's products. The total concentrations of Di-OPs ranged in 3577-95551 ng/m2 in the wipes and limit of detection-23002 ng/g in the materials. The Tri-OPs concentrations varied significantly in the ranges of 107218-1756892 ng/m2 and 2.13-503149 ng/g, respectively. Four industrial Di-OPs were detected in > 65% of the studied samples suggesting their direct application in the studied materials. Furthermore, we demonstrated for the first time that four non-industrial Di-OPs, e.g., bis(2-chloroethyl) phosphate, bis(1-chloro-2-propyl) phosphate, bis(1,3-dichloro-2-propyl) phosphate, and bis(butoxyethyl) phosphate, identified as degradation products of their respective Tri-OPs were also detected in these studied samples, which might act as important emission sources of Di-OPs in indoor environments. We estimated the burden of Di-OPs and Tri-OPs in a typical residential house and instrumental room, which both exhibited important contributions from furniture, building and decoration materials, and electrical/electronic devices. Limit health risk was posed to local people via air inhalation.

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.

Biotransformation of Organophosphate Diesters Characterized via In Vitro Metabolism and In Vivo Screening

Organophosphate diesters (di-OPEs), as additives in industrial applications and/or transformation products of emerging environmental pollutants, such as organophosphate triesters (tri-OPEs), have been found in the environment and biological matrices. The metabolic fate of di-OPEs in biological media is of great significance for tracing the inherent and precursor toxicity variations. This is the first study to investigate the metabolism of a suite of di-OPEs by liver microsomes and to identify any metabolite of metabolizable di-OPEs in in vitro and in vivo samples. Of the 14 di-OPEs, 5 are significantly metabolizable, and their abundant metabolites with hydroxyl, carboxyl, dealkylated, carbonyl, and/or epoxide groups are tentatively identified. More than half of the di-OPEs are detectable in human serum and/or wild fish tissues, and dibenzyl phosphate (DBzP), bis(2,3-dibromopropyl) phosphate (BDBPP), and isopropyl diphenyl phosphate (ip-DPHP) are first reported at a detectable level in humans and wildlife. Using an in vitro assay and a known biotransformation rule-based integrated screening strategy, 2 and 10 suspected metabolite peaks of DEHP are found in human serum and wild fish samples, respectively, and are then identified as phase I and phase II metabolites of DEHP. This study provides a novel insight into fate and persistence of di-OPE and confirms the presence of di-OPE metabolites in humans and wildlife.

Organophosphate Triesters and Their Transformation Products in Sediments of Mangrove Wetlands in the Beibu Gulf, South China Sea

As emerging pollutants, organophosphate esters (OPEs) have been reported in coastal environments worldwide. Nevertheless, information on the occurrence and ecological risks of OPEs, especially the related transformation products, in mangrove wetlands is scarce. For the first time, the coexistence and distribution of OP triesters and their transformation products in three mangrove wetlands in the Beibu Gulf were investigated using ultrasonication and solid-phase extraction, followed by UHPLC-MS/MS detection. The studied OPEs widely existed in all the sampling sites, with the total concentrations ranging from 6.43 ng/g dry weight (dw) to 39.96 ng/g dw and from 3.33 ng/g dw to 22.50 ng/g dw for the OP triesters and transformation products, respectively. Mangrove wetlands tend to retain more OPEs than the surrounding coastal environment. Pearson correlation analysis revealed that the TOC was not the sole factor in determining the OPEs' distribution, and degradation was not the main source of the transformation products in mangrove sediments in the Beibu Gulf. The ecological risks of selected OPEs for different organisms were also assessed, revealing a medium to high risk posed by OP diesters to organisms. The levels or coexistence of OPEs and their metabolites in mangroves need constant monitoring, and more toxicity data should be further studied to assess the effect on normal aquatic organisms.

Organophosphate flame retardants and their metabolites in the Pearl River Estuary: Occurrence, influencing factors, and ecological risk control strategies based on a mass balance model

Estuaries serve as crucial filters for land-based pollutants to the open sea, but there is a lack of information on the migration and fate of organophosphate flame retardants (OPFRs) within estuaries. This study focused on the Pearl River Estuary (PRE) by examining the co-occurrence of OPFRs and their metabolites and quantifying their transport fluxes using a mass balance model. The seawater concentrations of OPFRs and their metabolites exhibited significant seasonal variations (p < 0.01), while the sediment concentrations of OPFRs reflected the long-term distributional equilibrium in the PRE. The concentration of Σ9OPFRs in seawater showed a relentless dilution from the entrance to the offshore region in the normal and wet seasons, which was significantly in accordance with the gradients of pH, dissolved oxygen (DO), and salinity (p < 0.05). Furthermore, horizontal migration dominated the transport of OPFRs, and the inventory assessment revealed that both the water column and sediment were important reservoirs in the PRE. According to the estimated fluxes from the mass balance model, riverine input emerged as the principal pathway for OPFR entry into the PRE (1.55 × 105, 6.28 × 104, and 9.00 × 104 kg/yr in the normal, dry and wet seasons, respectively), whereas outflow to the open sea predominantly determined the main fates of the OPFRs. The risk quotient (RQ) results showed that EHDPHP (0.835) in water posed medium ecological risk, while other OPFRs and metabolites presented relatively lower risk (RQ < 0.1). The risk control effects were evaluated through scenario simulations of mathematical fitting between controllable source factors and the RQ of risky OPFR. The risk of EHDPHP in the PRE could be effectively reduced by restricting its concentrations in entrance region (<9.31, 8.67, and 12.7 ng/L in the normal, dry and wet seasons, respectively) of the PRE. This research offers foundational insights into environmental management and pollution control strategies for emerging pollutants in estuaries.

Presence of key cholinergic enzymes in human spermatozoa and seminal fluid†

Little is known about the non-neuronal spermic cholinergic system, which may regulate sperm motility and the acrosome reaction initiation process. We investigated the presence of the key acetylcholine (ACh)-biosynthesizing enzyme, choline acetyltransferase (ChAT), and the acetylcholine-degrading enzymes, acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) and two ACh-receptors in human spermatozoa and seminal plasma. Fresh ejaculates were used for intra- and extracellular flow cytometric analysis of ChAT, AChE, BChE, and alpha-7-nicotinic and M1-muscarinic ACh-receptors in sperm. For determining the source of soluble enzymes, frozen seminal samples (n = 74) were selected on two bases: (1) from vasectomized (n = 37) and non-vasectomized (n = 37) subjects and (2) based on levels of alpha-glucosidase, fructose, or zinc to define sample subgroups with high or low fluid contribution from the epididymis and seminal vesicle, and prostate, respectively. Flow cytometric analyses revealed that ChAT was expressed intracellularly in essentially all spermatozoa. ChAT was also present in a readily membrane-detachable form at the extracellular membrane of at least 18% of the spermatozoa. These were also highly positive for intra- and extracellular BChE (>83%) and M1 (>84%) and α7 (>59%) ACh-receptors. Intriguingly, the sperm was negative for AChE. Analyses of seminal plasma revealed that spermatozoa and epididymides were major sources of soluble ChAT and BChE, whereas soluble AChE most likely originated from epididymides and seminal vesicles. Prostate had relatively minor contribution to the pool of the soluble enzymes in the seminal fluid. In conclusion, human spermatozoa exhibited a cholinergic phenotype and were one of the major sources of soluble ChAT and BChE in ejaculate. We also provide the first evidence for ChAT as an extracellularly membrane-anchored protein.

Tissue distribution and trophic transfer of organophosphate triesters and diesters in three marine mammals of the Liaodong Bay and the Northern Yellow Sea

Tissue (muscle, liver, kidney, lung, and heart) distribution and trophic transfer of organophosphate (OP) triesters and diesters in stranded 10 minke whales, 20 spotted seals and 27 East Asian finless porpoises from the Liaodong Bay and the Northern Yellow Sea were evaluated. The OP triesters and diesters were widely found in the tissues of the three marine mammals and their preys, with mean concentrations ranging from below the limits of detection (LOD) to 4342 μg/kg dry weight (dw) and from below the LOD to 1460 μg/kg dw, respectively. Tissue-specific distribution of the OP triesters or diesters were found in the investigated marine mammals with chemical-specific and species-specific. Log Kow negatively affect the accumulation of OP diesters in the marine mammals (p < 0.05), which related to their accumulation pathway in the tissues. The biological traits of the three marine mammals, body length, gender and age could affect the distribution of several OP triesters or diesters. Yet more concern is that significantly biological magnification was found for bis(2-chloroethyl) phosphate (BCEP) with trophic magnification factor (TMF) of 5.36 and for tris(2-ethylhexyl) phosphate (TEHP)(TMF:2.88) along with the finless porpoise food web. These results considerably contribute to expanding understanding of OP triesters or diesters pollution on the organisms in marine ecosystem.

Face mask as an indicator and shield of human exposure to traditional and novel organophosphate esters

Herein, the trapping effectiveness of N95, filter KN95, medical surgical masks (MSMs), and disposable medical masks (DMMs) against 19 airborne traditional and novel organophosphate esters (OPEs) was evaluated. Laboratory simulations (n = 24 for each type of mask) showed that time-dependent accumulation of ∑19OPEs on the four types of masks ranged between 30.1 and 86.6 ng in 24 h, with the highest and lowest median amounts trapped by the N95 masks (53.3 ng) and DMMs (43.2 ng), respectively. The trapping efficiency of the four types of masks for ∑19OPEs decreased over time from 84 % to 39 % in 24 h, with N95 masks showing the highest median efficiency (70 %). Further, field investigations were conducted in five types of microenvironments (train, hospital, bus, supermarket, and canteen), and an analysis of 200 samples showed that ∑19OPEs were accumulated in the masks with a variable amount from 3.7 to 117 ng/mask. Consistent with the laboratory simulations, the N95 masks (29.0 ng/mask) exhibited the highest hourly median amount of trapped OPEs, followed by the KN95 masks (24.5 ng/mask), MSMSs (17.4 ng/mask), and DMMs (15.8 ng/mask). Triethyl phosphate (TEP), tris(1-chloro-2-propyl) phosphate (TCIPP), tri-n-butyl phosphate (TNBP), and cresyl diphenyl phosphate (CDP) as well as 4-isopropylphenyl diphenyl phosphate (4IPPDPP) and 2,4-diisopropylphenyl diphenyl phosphate (24DIPPDPP) were the most commonly detected traditional and novel OPEs. Based on the amount of OPEs trapped on the masks, we estimated the concentration of ∑19OPEs in the train microenvironment to be the highest (222 ng/m3), which is approximately 2-5 times higher than that in the other microenvironments. The results of this study prove that masks can effectively protect humans from exposure to OPEs and act as low-cost indicators of indoor contamination.

An overview of current knowledge on organophosphate di-esters in environment: Analytical methods, sources, occurrence, and behavior

Organophosphate di-esters (di-OPEs) are highly related to tri-OPEs. The presence of di-OPEs in the environment has gained global concerns, as some di-OPEs are more toxic than their respective tri-OPE compounds. In this study, current knowledge on the analytical methods, sources, environmental occurrence, and behavior of di-OPEs were symmetrically reviewed by compiling data published till March 2023. The determination of di-OPEs in environmental samples was exclusively achieved with liquid chromatography mass spectrometry operated in negative mode. There are several sources of di-OPEs, including industrial production, biotic and abiotic degradation from tri-OPEs under environmental conditions. A total of 14 di-OPE compounds were determined in various environments, including dust, sediment, sludge, water, and atmosphere. The widespread occurrence of di-OPEs suggested that human and ecology are generally exposed to di-OPEs. Among all environmental matrixes, more data were recorded for dust, with the highest concentration of di-OPEs up to 32,300 ng g-1. Sorption behavior, phase distribution, gas-particle partitioning behavior was investigated for certain di-OPEs. Suggestions on future studies in the perspective of human exposure to and environmental behavior of di-OPEs were proposed.

Associations of Organophosphate Ester Flame Retardant Exposures during Pregnancy with Gestational Duration and Fetal Growth: The Environmental influences on Child Health Outcomes (ECHO) Program

BACKGROUND

Widespread exposure to organophosphate ester (OPE) flame retardants with potential reproductive toxicity raises concern regarding the impacts of gestational exposure on birth outcomes. Previous studies of prenatal OPE exposure and birth outcomes had limited sample sizes, with inconclusive results.

OBJECTIVES

We conducted a collaborative analysis of associations between gestational OPE exposures and adverse birth outcomes and tested whether associations were modified by sex.

METHODS

We included 6,646 pregnant participants from 16 cohorts in the Environmental influences on Child Health Outcomes (ECHO) Program. Nine OPE biomarkers were quantified in maternal urine samples collected primarily during the second and third trimester and modeled as log 2 -transformed continuous, categorized (high/low/nondetect), or dichotomous (detect/nondetect) variables depending on detection frequency. We used covariate-adjusted linear, logistic, and multinomial regression with generalized estimating equations, accounting for cohort-level clustering, to estimate associations of OPE biomarkers with gestational length and birth weight outcomes. Secondarily, we assessed effect modification by sex.

RESULTS

Three OPE biomarkers [diphenyl phosphate (DPHP), a composite of dibutyl phosphate and di-isobutyl phosphate (DBUP/DIBP), and bis(1,3-dichloro-2-propyl) phosphate] were detected in > 85 % of participants. In adjusted models, DBUP/DIBP [odds ratio (OR) per doubling = 1.07 ; 95% confidence interval (CI): 1.02, 1.12] and bis(butoxyethyl) phosphate (OR for high vs. nondetect = 1.25 ; 95% CI: 1.06, 1.46), but not other OPE biomarkers, were associated with higher odds of preterm birth. We observed effect modification by sex for associations of DPHP and high bis(2-chloroethyl) phosphate with completed gestational weeks and odds of preterm birth, with adverse associations among females. In addition, newborns of mothers with detectable bis(1-chloro-2-propyl) phosphate, bis(2-methylphenyl) phosphate, and dipropyl phosphate had higher birth weight-for-gestational-age z -scores (β for detect vs. nondetect = 0.04 - 0.07 ); other chemicals showed null associations.

DISCUSSION

In the largest study to date, we find gestational exposures to several OPEs are associated with earlier timing of birth, especially among female neonates, or with greater fetal growth. https://doi.org/10.1289/EHP13182.

Establishment of an Integrated Nontarget and Suspect Screening Workflow for Organophosphate Diesters (Di-OPEs) and Identification of Seven Previously Unknown Di-OPEs in Food Contact Plastics

In this study, an innovative, integrated nontarget and suspect screening workflow was developed for identifying organophosphate diesters (di-OPEs) using high-resolution mass spectrometry. The workflow featured the utilization of 0.02% acetic acid as a mobile-phase additive, differentiated screening methods for alkyl and aryl di-OPEs, and a combination of electrospray negative ionization and positive ionization. Using this workflow, 18 di-OPEs were identified in the extracts of 75 food contact plastic (FCP) samples sourced from South China. Among these, six alkyl and one aryl di-OPEs were previously unknown (one unequivocal identification and six probable structures based on diagnostic evidence). (Semi)quantification revealed that bis(2,4-di-tert-butylphenyl) phosphate was the major di-OPE in FCPs, with a median concentration of 1079 ng/g (range: 23.4-158,414 ng/g). The migration efficiencies of di-OPEs from an FCP sample to four kinds of food simulants were between 2.58 and 54.3%. This study offered a useful workflow for the comprehensive profiling of di-OPEs in FCPs.

"Cocktail" of environmental chemicals and early reproductive outcomes of IVF: The insight from paternal and maternal exposure

BACKGROUND

Humans are exposed to various chemicals, including organophosphate esters (OPEs), phthalates (PAEs), and phenols. The effects on early reproductive outcomes of in vitro fertilization (IVF) remain unclear.

METHODS

We recruited 192 women and 157 men who underwent IVF treatment. A total of forty-nine urinary chemicals were detected, including six OPEs, fifteen PAEs, six parabens, two chlorophenols, nine bisphenols, five benzophenones, and six synthetic phenolic antioxidants. We examined the individual and joint effects of parental chemical exposure on early reproductive outcomes.

RESULTS

We found that certain chemicals were associated with early reproductive outcomes in Poisson regression models. For example, urinary diphenyl phosphate was negatively associated with high-quality embryos in both female (β: -0.12, 95%CI: -0.17, -0.07) and male partners (β: -0.09, 95%CI: -0.15, -0.03). A negative association was found between mixed chemicals and high-quality embryos in Bayesian kernel machine regression, weighted quantile sum regression (β: -0.34, 95%CI: -0.60, -0.07), and quantile-based g-computation model (β: -0.69, 95%CI: -1.34, -0.05) among female partners. Paternal mixture exposure was not associated with early reproductive outcomes.

CONCLUSIONS

Our results indicated that increased exposure to environmental chemicals was associated with adverse early reproductive outcomes of IVF, especially female partners.

Indirect Emissions from Organophosphite Antioxidants Result in Significant Organophosphate Ester Contamination in China

Organophosphite antioxidants (OPAs) have been seriously neglected as potential sources of organophosphate esters (OPEs) in environments. This study utilizes a modeling approach to quantify for the first time national emissions and multimedia distributions of triphenyl phosphate (TPHP)─a well-known flame retardant─and three novel OPEs: tris(2,4-ditert-butylphenyl) phosphate (AO168═O), bis(2,4-ditert-butylphenyl) pentaerythritol diphosphate (AO626═O2), and trisnonylphenol phosphate (TNPP). Emphasis is on the quantitative assessment of OPA source in China. TPHP has 1.1-9.7 times higher emission (300 Mg/year in 2019 with half from OPA sources) than AO168═O (278 Mg/year), AO626═O2 (53 Mg/year), and TNPP (32 Mg/year), but AO168═O is predominant in environments (63-79%) except freshwaters. About 72-99% of the studied OPEs are emitted via air, with 88-99% ultimately distributed into soils as the major sink. OPA-source emissions contribute 9.5-57% and 4.7-56% of TPHP masses and concentrations (except in sediments) in different media, respectively. Both AO168═O and AO626═O2 exhibit high overall persistence ranging between 2 and 11 years. Source emissions and environmental concentrations are elevated in economically developed areas, while persistence is higher in northern areas, where precipitation and temperature are lower. This study shows the significance of the sources of OPA to OPE contamination, which supports chemical management of these substances.

Endoplasmic reticulum stress participates in apoptosis of HeLa cells exposed to TPHP and OH-TPHP via the eIF2α-ATF4/ATF3-CHOP-DR5/P53 signaling pathway

Purpose

Triphenyl phosphate (TPHP) is a widely used organophosphate flame retardant, which can be transformed in vivo into diphenyl phosphate (DPHP) and 4-hydroxyphenyl phosphate (diphenyl) ester (OH-TPHP) through biotransformation process. Accumulation of TPHP and its derivatives in biological tissues makes it necessary to investigate their toxicity and molecular mechanism.

Methods

The present study evaluated the cellular effects of TPHP, DPHP, and OH-TPHP on cell survival, cell membrane damage, oxidative damage, and cell apoptosis using HeLa cells as in vitro model. RNA sequencing and bioinformatics analysis were conducted to monitor the differently expressed genes, and then RT-qPCR and Western bolt were used to identify potential molecular mechanisms and key hub genes.

Results

Results showed that OH-TPHP had the most significant cytotoxic effect in HeLa cells, followed by TPHP; and no significant cytotoxic effects were observed for DPHP exposure within the experimental concentrations. Biological function enrichment analysis suggested that TPHP and OH-TPHP exposure may induce endoplasmic reticulum stress (ERS) and cell apoptosis. The nodes filtering revealed that ERS and apoptosis related genes were involved in biological effects induced by TPHP and OH-TPHP, which may be mediated through the eukaryotic translation initiation factor 2α/activating transcription factor 4 (ATF4)/ATF3- CCAAT/ enhancer-binding protein homologous protein (CHOP) cascade pathway and death receptor 5 (DR5) /P53 signaling axis.

Conclusion

Above all, these findings indicated that ERS-mediated apoptosis might be one of potential mechanisms for cytotoxicity of TPHP and OH-TPHP.

Postbiotics as Potential Detoxification Tools for Mitigation of Pesticides

Pesticides possess a pivotal role in the realm of agriculture and food manufacturing, as they effectively manage the proliferation of weeds, insects, plant pathogens, and microbial contaminations. They are valuable in some ways, but if misused, they can cause health issues like cancer, reproductive toxicity, neurological illnesses, and endocrine system disturbances. In this regard, practical methods for reducing pesticide residue in food should be used. For reducing pesticide residue in food processing, some strategies have been suggested. Recent research has been done on detoxification processes, including microorganisms like probiotics and their metabolites. The term "postbiotics" describes soluble substances, such as peptides, enzymes, teichoic acids, muropeptides generated from peptidoglycans, polysaccharides, proteins, and organic acids that are secreted by living bacteria or released after bacterial lysis. Due to their distinct chemical makeup, safe dosage guidelines, lengthy shelf lives, and presence of various signaling molecules that may have antioxidant, anti-inflammatory, anti-obesogenic, immunomodulatory, anti-hypertensive, and immunomodulatory effects, these postbiotics have attracted interest. They also can detoxify heavy metals, mycotoxins, and pesticides. Hydrolytic enzymes have been proposed as a potential mechanism for pesticide degradation. Postbiotics can also reduce reactive oxygen species production, enhance gastrointestinal barrier function, reduce inflammation, and modulate host xenobiotic metabolism. This review highlights pesticide residues in food products, definitions and safety aspect of postbiotics, as well as their biological role in detoxification of pesticides and the protective role of these compounds against the adverse effects of pesticides.

Review on typical organophosphate diesters (di-OPEs) requiring priority attention: Formation, occurrence, toxicological, and epidemiological studies

The impact of primary metabolites of organophosphate triesters (tri-OPEs), namely, organophosphate diesters (di-OPEs), on the ecology, environment, and humans cannot be ignored. While extensive studies have been conducted on tri-OPEs, research on the environmental occurrence, toxicity, and health risks of di-OPEs is still in the preliminary stage. Understanding the current research status of di-OPEs is crucial for directing future investigations on the production, distribution, and risks associated with environmental organophosphate esters (OPEs). This paper specifically reviews the metabolization process from tri-OPEs to di-OPEs and the occurrence of di-OPEs in environmental media and organisms, proposes typical di-OPEs in different media, and classifies their toxicological and epidemiological findings. Through a comprehensive analysis, six di-OPEs were identified as typical di-OPEs that require prioritized research. These include di-n-butyl phosphate (DNBP), bis(2-butoxyethyl) phosphate (BBOEP), bis(1,3-dichloro-2-propyl) phosphate (BDCIPP), bis(2-chloroethyl) phosphate (BCEP), bis(1-chloro-2-propyl) phosphate (BCIPP), and diphenyl phosphate (DPHP). This review provides new insights for subsequent toxicological studies on these typical di-OPEs, aiming to improve our understanding of their current status and provide guidance and ideas for research on the toxicity and health risks of di-OPEs. Ultimately, this review aims to enhance the risk warning system of environmental OPEs.

Established and emerging organophosphate esters (OPEs) and the expansion of an environmental contamination issue: A review and future directions

The list of organophosphate esters (OPEs) reported in the environment continues to expand as evidenced by the increasing number of OPE studies in the literature. However, there remains a general dearth of information on more recently produced and used OPEs that are proving to be emerging environmental contaminants. The present review summarizes the available studies in a systematic framework of the current state of knowledge on the analysis, environmental fate, and behavior of emerging OPEs. This review also details future directions to better understand emerging OPEs in the environment. Firstly, we make recommendations that the current structural/practical abbreviations and naming of OPEs be revised and updated. A chemical database (CDB) containing 114 OPEs is presently established based on the suspect list from the current scientific literature. There are 12 established OPEs and a total of 83 emerging OPEs that have been reported in human and/or biota samples. Of the emerging OPEs more than 80% have nearly 100% detection frequencies in samples of certain environmental media including indoor air, wastewater treatment plants, sediment, and fish. In contrast to OPEs considered established contaminants, most emerging OPEs have been identified more recently due to the more pervasive use of high-resolution mass spectrometry (HRMS) based approaches and especially gas or liquid chromatography coupled with HRMS-based non-target analysis (NTA) of environmental sample fractions. Intentional/unintentional industrial use and non-industrial formation are sources of emerging OPEs in the environment. Predicted physical-chemical properties in silico of newer, molecularly larger and more oligomeric OPEs strongly suggest that some compounds such as bisphenol A diphenyl phosphate (BPA-DPP) are highly persistent, bioaccumulative and/or toxic. Limited information on laboratory-based toxicity data has shown that some emerging OPEs elicit harmful effects such as cytotoxicity, development toxicity, hepatotoxicity, and endocrine disruption in exposed humans and mammals. Established, and to a much lesser degree emerging OPEs, have also been shown to transform and degrade in biota and possibly alter their toxicological effects. Research on emerging OPE contaminants is presently limited and more study is warranted on sample analysis methods, source apportionment, transformation processes, environmental behavior, biomarkers of exposure and toxicity.

Fate of organophosphate flame retardants (OPFRs) in the "Cambi® TH + AAD" of sludge in a WWTP in Beijing, China

Organophosphate flame retardants (OPFRs) are emerging environmental pollutants that cause endocrine disruption, neurotoxicity, and reproductive toxicity. Sewage sludge is an important source of tri-OPFRs that are released into the environment. The occurrence, distribution, and ecological risk of OPFRs in the full-scale "Cambi® thermal hydrolysis (TH) + advanced anaerobic digestion (AAD) + plate-frame pressure filtration" sludge treatment process is closely related to the application of sewage sludge. We tested sludge samples from a wastewater treatment plant in Beijing, China. Nine tri-OPFRs were detected in the sludge samples collected at different treatment units during four seasons. The ΣOPFRs decreased from 1,742.65-2,579.68 ng/g to 971.48-1,702.22 ng/g. The mass flow of tri-OPFRs in treated sludge decreased by 61.4%, 48.9%, 42.4%, and 63.9% in spring, summer, autumn and winter, respectively, effectively reducing the corresponding ecological risk. The ecological risk of tri-OPFRs in sludge in forestland utilization mainly lies in chlorinated tri-OPFRs, especially TCPP and TCEP. No >42.20 t/hm2 of sludge could be used continuously for one year to prevent tri-OPFRs from exceeding the low ecological risk level, indicating that the current commonly applied proportion of sludge (1.6-30 t/hm2) will likely not raise the ecological risk of tri-OPFRs.

Nontarget Identification of Novel Organophosphorus Flame Retardants and Plasticizers in Rainfall Runoffs and Agricultural Soils around a Plastic Recycling Industrial Park

Plastic recycling and reprocessing activities may release organophosphate ester (OPE) flame retardants and plasticizers into the surrounding environment. However, the relevant contamination profiles and impacts remain not well studied. This study investigated the occurrence of 28 OPEs and their metabolites (mOPEs) in rainfall runoffs and agricultural soils around one of the largest plastic recycling industrial parks in North China and identified novel organophosphorus compounds (NOPs) using high-resolution mass spectrometry-based nontarget analysis. Twenty and twenty-seven OPEs were detected in runoff water and soil samples, with total concentrations of 86.0-2491 ng/L and 2.53-199 ng/g dw, respectively. Thirteen NOPs were identified, of which eight were reported in the environment for the first time, including a chlorine-containing OPE, an organophosphorus heterocycle, a phosphite, three novel OPE metabolites, and two oligomers. Triphenylphosphine oxide and diphenylphosphinic acid occurred ubiquitously in runoffs and soils, with concentrations up to 390 ng/L and 40.2 ng/g dw, respectively. The downwind areas of the industrial park showed elevated levels of OPEs and NOPs. The contribution of hydroxylated mOPEs was higher in soils than in runoffs. These findings suggest that plastic recycling and reprocessing activities are significant sources of OPEs and NOPs and that biotransformation may further increase the ecological and human exposure risk.

New Perspective to Understand and Prioritize the Ecological Impacts of Organophosphate Esters and Transformation Products in Urban Stormwater and Sewage Effluents

Due to their prevalence in urban contaminated water, the driving factors of organophosphate esters (OPEs) need to be well examined, and their related ecological impacts should include that of their transformation products (TPs). Additionally, a robust framework needs to be developed to integrate multiple variables related to ecological impacts for improving the ecological health assessment. Therefore, OPEs and TPs in urban stormwater and wastewater in Hong Kong were analyzed to fill these gaps. The results revealed that the total concentrations of OPEs in stormwater were positively correlated with the area of transportation land. Individual TP concentrations and the mass ratios of individual TPs/OPEs were somewhat higher in sewage effluents than that in stormwater. OPEs generally showed relatively higher risk quotients than TPs; however, the total risk quotients increased by approximately 38% when TPs were factored in. Moreover, the molecular docking results suggested that the investigated TPs might cause similar endocrine disruption in marine organisms as their parent OPEs. This study employed the Toxicological-Priority-Index scheme to successfully integrate the ecological risks and endocrine-disrupting effects to refine the ecological health assessment of the exposure to OPEs and their TPs, which can better inform the authority on the prioritization for regulating these contaminants of emerging concern in urban built environments.

Organophosphate esters in soils of Beijing urban parks: Occurrence, potential sources, and probabilistic health risks

Organophosphate esters (OPEs) are an emerging contaminant widely distributed in the soil. OPEs have drawn increasing attention for their biological toxicity and possible threat to human health. This research investigated the pollution characteristics of two typical OPEs, organophosphate triesters (tri-OPEs) and organophosphate diesters (di-OPEs), in soils of 104 urban parks in Beijing. The median concentrations of Σ₁₁tri-OPEs and Σ₈di-OPEs were 157 and 17.9 ng/g dw, respectively. Tris(2-chloroisopropyl) phosphate and bis(2-ethylhexyl) phosphate were the dominant tri-OPE and di-OPE, respectively. Consumer materials (such as building insulation and decorative materials), traffic emissions, and reclaimed water irrigation may be critical sources of tri-OPEs in urban park soils. Di-OPEs mainly originated from the degradation of parent compounds and industrial applications. Machine learning models were employed to determine the influencing factors of OPEs and predict changes in their concentrations. The predicted OPEs concentrations in Beijing urban park soils in 2025 and 2030 are three times and five times those in 2018, respectively. According to probabilistic health risk assessment, non-carcinogenic and carcinogenic risks of OPEs can be negligible for children and adults. Our results could inform measures for preventing and controlling OPEs pollution in urban park soils.

Lipid metabolic disturbance induced by triphenyl phosphate and hydroxy metabolite in HepG2 cells

Triphenyl phosphate (TPHP) has been widely used as flame retardants and been detected with increasing frequency in environment. TPHP can transform into mono-hydroxylated phosphate (OH-TPHP) and diester diphenyl phosphate (DPHP) through biotransformation. So far, information on the cytotoxicity and molecular regulatory mechanisms of TPHP metabolites are still limit. This study investigated the adverse effects of TPHP, OH-TPHP, and DPHP in HepG2 cells in terms of cell proliferation, lactate dehydrogenase release, reactive oxygen species generation, and mitochondrial membrane potential. The transcriptomic changes were measured using RNA sequencing, and bioinformatics characteristics including biological functions, signal pathways and protein-protein interaction were analyzed to explore the potential molecular mechanisms. Results displayed that the order of cytotoxicity was OH-TPHP> TPHP> DPHP. The prioritized biological functions changes induced by TPHP and OH-TPHP were correlated with lipid metabolism. Significant lipid accumulation was observed as confirmed by increased total cholesterol and triglycerides contents, and enhanced oil red O staining. Enrichment of PPARα/γ and down-stream genes suggested the participation of PPARs signal pathway in lipid metabolism disorder. In addition, TPHP and OH-TPHP induced endoplasmic reticulum stress (ERS), which was further confirmed by the ERS inhibitor experiment. In general, TPHP and OH-TPHP had obvious cytotoxic effects in HepG2 cells. PPARs signal pathway and endoplasmic reticulum stress may be involved in the lipid metabolism disorder induced by TPHP and OH-TPHP.

Co-occurrence and distribution of organophosphate tri- and di-esters in dust and hand wipes from an e-waste dismantling plant in central China

Electronic waste (e-waste) dismantling facilities are a well-known source of emerging contaminants including organophosphate esters (OPEs). However, little information is available regarding the release characteristics and co-contaminations of tri- and di-esters. This study, therefore, investigated a broad range of tri- and di-OPEs in dust and hand wipe samples collected from an e-waste dismantling plant and homes as comparison. The median ∑tri-OPE and ∑di-OPE levels in dust and hand wipe samples were approximately 7- and 2-fold higher than those in the comparison group, respectively (p < 0.01). Triphenyl phosphate (median: 11,700 ng/g and 4640 ng/m²) and bis(2-ethylhexyl) phosphate (median: 5130 ng/g and 940 ng/m²) were the dominant components of tri- and di-OPEs, respectively. The combination of Spearman rank correlations and the determinations of molar concentration ratios of di-OPEs to tri- OPEs revealed that apart from the degradation of tri-OPEs, di-OPEs could originate from direct commercial application, or as impurities in tri-OPE formulas. Significant positive correlations (p < 0.05) were found for most tri- and di-OPE levels between the dust and hand wipes from dismantling workers, whereas this was not observed in those from the ordinary microenvironment. Our results provide robust evidence that e-waste dismantling activities contribute to OPEs contamination in the surroundings and further human exposure pathways and toxicokinetics are needed to be elucidated.

Analysis and subcellular distribution of organophosphate esters (OPEs) in rice tissues

Recent studies have identified the ability of plants to uptake and translocate organophosphate esters (OPEs) within cells. In response to the increasing interest in OPEs and their occurrence in paddy fields and rice, the current study aimed to present an effective and sensitive GC-MS based methodology for quantitative determination of 11 OPEs with octanol-water coefficients ranging from 1.6 to 10. Rice was sonicated with hexane and dichloromethane, and fractionated on two columns: one consisting of neutral alumina, and neutral silica, and the other consisting of graphitized carbon black. Method precision was validated using spiked rice (n = 30) and procedural blanks (n = 9). The mean recovery of matrix spikes for all target OPEs were within 78-110% with relative standard deviation lower than 25%, with a few exceptions. This method was applied to process the wild rice (O. sativa) in which tri-n-propyl phosphate was the dominant targeted OPE. The recoveries of surrogate standards were 81 ± 17% for d₁₂- tris(2-chloroethyl) phosphate and 95 ± 8.8% for ¹³C₁₂- triphenyl phosphate. The developed method was further used to examine the recoveries of target OPEs in the subcellular structure of rice tissues, including cell wall, cell organelles, cell water-soluble fractions, and cell residue. Recoveries of most target OPEs were in the range of 50-150%; however, ion enhancement was observed for four OPEs in root and shoot tissues. Hydrophobic OPEs accumulated in the cell wall, cell residue, and cell organelles while chlorinated OPEs mainly distributed in the cell water-soluble fraction. These results provide new insight for the ecological risk assessment of OPEs in an important food staple.

Occurrence and risk assessment of organophosphate esters in global aquatic products

Organophosphate esters (OPEs), as an important class of new pollutants, have been pervasively detected in global aquatic products, arousing widespread public concern due to their potential bioaccumulative behavior and consequent risks. With the continuous improvement of living standards of citizens, there have been constant increment of the proportion of aquatic products in diets of people. The levels of OPEs exposed to residents may also be rising due to the augmented consumption of aquatic products, posing potential hazards on human health, especially for people in coastal areas. The present study integrated the concentrations, profiles, bioaccumulation, and trophic transfer of OPEs in global aquatic products, including Mollusca, Crustacea, and fish, evaluated health risks of OPEs through aquatic products in daily diets by Mont Carol Simulation (MCS), and found Asia has been the most polluted area in terms of the concentration of OPEs in aquatic products, and would have been increasingly polluted. Among all studied OPEs, chlorinated OPEs generally showed accumulation predominance. It is worth noting that some OPEs were found bioaccumulated and/or biomagnified in aquatic ecosystems. Though MCS revealed relative low exposure risks of residents, sensitive and special groups such as children, adolescents, and fishermen may face more serious health risks than the average residents. Finally, knowledge gaps and recommendations for future research are discussed encouraging more long-term and systematic global monitoring, comprehensive studies of novel OPEs and OPEs metabolites, and more toxicological studies to completely evaluate the potential risks of OPEs.

Degradation and phosphorus immobilization treatment of organophosphate esters hazardous waste by Fe-Mn bimetallic oxide

Organophosphate esters (OPEs) waste is difficult to dispose effectively because of its stability and the potential risk of P element. In this study, taking one typical organic extractant of tributyl phosphate (TBP) as an example, we proposed a strategy to treat OPEs inspired by chemical looping combustion (CLC) technology-oxygen carrier immobilization process (OCIP), aiming at efficient TBP degradation and simultaneous P immobilization. Adopting Fe-Mn bimetallic oxide (FMBO) as oxygen carrier, an almost 100% P immobilization efficiency was achieved under recommended conditions which were obtained by response surface methodology. Meanwhile, gaseous products released from TBP degradation, e.g., non-methane hydrocarbon, was lower than the maximum allowable emission concentration limit. Further characterizations implied that P-species released from reaction process were mainly immobilized as stable inorganic forms of metaphosphate, phosphate and pyrophosphate. On the basis of identifying degradation intermediates, we proposed a possible degradation pathways. FMBO as an oxygen carrier provided sufficient oxygen molecules for flameless combustion of OCIP process. Electron paramagnetic resonance measurement confirmed the existence of oxygen vacancies on FMBO surface, which contributed to the formation of •O₂^-. Oxidation by oxygen molecules and •O₂^- attack resulted in the degradation and mineralization of TBP, with simultaneously achieving P stabilization.

Organophosphate tri- and diesters in source water supply and drinking water treatment systems of a metropolitan city in China

The water contaminations with organophosphate triesters (tri-OPEs) and diesters (di-OPEs) have recently provoked concern. However, the distributions of these compounds in natural water sources and artificial water treatment facilities are poorly characterized. A comprehensive study was therefore performed to measure their concentrations in a water source, a long-distance water pipeline, and a drinking water treatment plant (DWTP). Eight tri-OPEs and 3 di-OPEs were found to be widely distributed, with total concentrations in source water and pipelines ranging from 290.6 to 843.9 ng/L. The most abundant pollutants were tris(1-chloro-2-propyl) phosphate (TCPP), triethyl phosphate, tri-n-butyl phosphate (TnBP), and diphenyl phosphate (DPhP). Di-OPEs appeared to be removed less efficiently in the DWTP than the parent tri-OPEs, and the elimination efficiencies of tri-OPEs were structure-dependent. Long-distance pipeline transportation had no significant effect on the distributions of tri- and di-OPEs. Statistical analysis suggested that the sources of di-OPEs and the corresponding tri-OPEs differed, as did those of DPhP and di-n-butyl phosphate. A risk analysis indicated that tri-OPEs present limited ecological risks that are mainly due to TnBP and TCPP, and that the human health risks of tri-OPEs are negligible. However, di-OPEs (especially DPhP) may increase these risks. Further studies on the risks posed by di-OPEs in aquatic environments are therefore needed.

Occurrence and ecological risk assessment of organophosphate esters in surface water from rivers and lakes in urban Hanoi, Vietnam

In this study, an investigation on the pollution status, distribution, and ecological risk to the aquatic organisms of six organophosphate tri-esters (tri-OPEs) and two organophosphate tri-esters (di-OPEs) in surface water in urban Hanoi, Vietnam were conducted. In 37 surveyed water samples (6 rivers and 17 lakes), all eight targeted OPEs were discovered with a detection frequency (DF) of 41-100% and the concentration varied largely from below the method detection limit (<MDL) to 6138 ng L^-1. The total concentrations of six tri-OPEs (Ʃ₆tri-OPEs) were 46-3644 ng L^-1 (average 1409 ng L^-1) and the total concentrations of two di-OPEs (Ʃ₂di-OPEs) ranged from 2.6 to 6138 ng L^-1 (average 351 ng L^-1). In general, the Ʃ₆tri-OPEs in water samples collected in rivers (average 2262 ng L^-1) were higher than those in lakes (average 1000 ng L^-1). The most dominant chemical was tris(2-chloro-1-methyl ethyl) phosphate (TCPP) with a DF of 100% and took up 75% (on average) of Ʃ₆tri-OPEs. Principal component analysis showed that most of the tri- and di-OPEs in lakes may come from similar emission sources. While, there were at least four different origins of organophosphate esters (OPEs) in rivers in urban Hanoi. The risk quotient (RQ) was estimated for the detected concentration of tri- and di-OPEs in water samples and the toxicological relevant concentration for three trophic groups of algae, crustaceans, and fish. The RQs and the total of RQs for each group were lower than 1, indicating that the effects of each OPE and their OPEs' combined effects on the aquatic environment in Hanoi were at low to medium levels.

Exposures to Organophosphate Esters and Respiratory Morbidity among School-Aged Children with Asthma

Organophosphate esters (OPEs) are an emerging class of chemicals used in a variety of consumer products as flame retardants, plasticizers, and additives. While prior epidemiologic studies suggest that OPEs may impact respiratory health, results remain inconclusive. We examined associations between urinary biomarkers of OPEs and symptoms of respiratory morbidity in a panel study of 147 predominantly Black school-aged children with asthma living in Baltimore City, Maryland. The study consisted of up to four seasonal, week-long, in-home visits where urine samples and self-reported asthma symptoms were collected on days 4 and 7 (n_samples = 438). We quantified concentrations of nine urinary OPE biomarkers: bis(2-chloroethyl) phosphate (BCEtp), bis(1-chloro-2-propyl) phosphate (BCPP), bis(1,3-dichloro-2-propyl) phosphate (BDCIPP), di-n-butyl phosphate (DBuP), di-benzyl phosphate (DBzP), di-o-cresylphosphate (DOCP), di-p-cresylphosphate (DPCP), di-(2-propylheptyl) phthalate (DPHP), and 2,3,4,5-tetrabromo benzoic acid (TBBA). We estimated prevalence odds ratios (POR) of respiratory morbidity symptoms using logistic regression with generalized estimating equations to account for our repeated measure design. We assessed BDCIPP and DPHP as continuous (log₂) concentrations and dichotomized exposure of BCEtP, DBuP, and DPCP (detect vs non-detect) based on their lower detection frequencies. We adjusted models for season, visit day, age, gender, caregiver education, health insurance type, exposure to household smoking, atopy, and PM_2.5. Higher DPHP concentrations were significantly associated with odds of daytime symptoms (POR: 1.26; 95% CI: 1.04-1.53; p = 0.02) where daytime symptoms consisted of trouble breathing due to asthma, reporting bother caused by asthma, and/or limitation in activities due to asthma. DBuP detection was associated with use of rescue medication on the day of sample collection (POR: 2.36; 95% CI: 1.05-5.29; p = 0.04). We also observed several consistent, albeit non-significant (p > 0.05), positive associations for BCEtP and DPCP and respiratory morbidity measures. This is the first study to evaluate the relationship between OPE biomarkers and respiratory morbidity symptoms in children with asthma, and findings suggest that further studies are warranted to confirm whether these associations are causal.

Meta-omics elucidates key degraders in a bacterial tris(2-butoxyethyl) phosphate (TBOEP)-degrading enrichment culture

Organophosphate esters (OPEs) are emerging contaminants of growing concern, and there is limited information about the bacterial transformation of OPEs. In this study, we investigated the biotransformation of tris(2-butoxyethyl) phosphate (TBOEP), a frequently detected alkyl-OPE by a bacterial enrichment culture under aerobic conditions. The enrichment culture degraded 5 mg/L TBOEP following the first-order kinetics with a reaction rate constant of 0.314 h^-1. TBOEP was mainly degraded via ether bond cleavage, evidenced by the production of bis(2-butoxyethyl) hydroxyethyl phosphate, 2-butoxyethyl bis(2-hydroxyethyl) phosphate, and 2-butoxyethyl (2-hydroxyethyl) hydrogen phosphate. Other transformation pathways include terminal oxidation of the butoxyethyl group and phosphoester bond hydrolysis. Metagenomic sequencing generated 14 metagenome-assembled genomes (MAGs), showing that the enrichment culture primarily consisted of Gammaproteobacteria, Bacteroidota, Myxococcota, and Actinobacteriota. One MAG assigned to Rhodocuccus ruber strain C1 was the most active in the community, showing upregulation of various monooxygenase, dehydrogenase, and phosphoesterase genes throughout the degradation process, and thus was identified as the key degrader of TBOEP and the metabolites. Another MAG affiliated with Ottowia mainly contributed to TBOEP hydroxylation. Our results provided a comprehensive understanding of the bacterial TBOEP degradation at community level.

Associations of urinary organophosphate esters metabolites with asthma and lung function in adolescents

BACKGROUND

Organophosphate esters (OPEs) are ubiquitously detected in environments and their exposure may affect respiratory health. However, epidemiological evidence, particularly among adolescents, is very limited.

OBJECTIVE

We aimed to investigate the associations of urinary OPEs metabolites with asthma and lung function among adolescents and to identify potential effect modifiers.

METHODS

Included were 715 adolescents aged 12-19 years old participating in the National Health and Nutrition Examination Survey (NHANES) 2011-2014. Multivariable binary logistic regression and linear regression were used to assess associations with asthma and lung function, respectively. Stratified analyses were conducted to assess the effect modifications of serum sex hormones, vitamin D levels, and body mass index (BMI).

RESULTS

After multivariable adjustment, we found that bis(2-chloroethyl) phosphate (BCEP) (3rd tertile [T3] vs 1st tertile [T1], OR = 1.87, 95% CI: 1.08, 3.25; P-trend=0.029) and diphenyl phosphate (DPHP) (T3 vs T1, OR = 2.52, 95%CI: 1.25, 5.04; P-trend=0.013) were associated with elevated odds of asthma in all adolescents. Sex-stratified analyses revealed that associations of these two OPEs metabolites tended to be stronger in males. Meanwhile, BCEP and the molecular sum of OPEs metabolites (∑OPEs) were significantly associated with declined lung function, either in all adolescents or by sex. Furthermore, stratified analyses revealed that positive associations of OPEs metabolites with asthma tended to be stronger among adolescents with insufficient levels of Vitamin D (VD < 50 nmol/L), relatively high levels of total testosterone (≥356 ng/dL and ≥22.5 ng/dL for males and females, respectively), or low levels of estradiol (<19.1 pg/mL and <47.3 pg/mL for males and females, respectively).

SIGNIFICANCE

Certain urinary OPEs metabolites, especially DPHP and BCEP, were associated with elevated odds of asthma and declined lung function in adolescents. Such associations might be partly modified by levels of VD and sex steroid hormones.

IMPACT STATEMENT

The observed associations of urinary OPEs metabolites with increased risk of asthma and declined lung function highlight the potential hazard of OPEs exposure to respiratory health among adolescents.

Regional Distribution of Atmospheric Organophosphate Tri-/Diesters in the Pearl River Delta: Possible Emission, Photo-degradation, and Atmospheric Transportation

The regional characteristics of atmospheric organophosphate triesters (OPEs) and organophosphate diesters (Di-OPs) in the Pearl River Delta (PRD) were investigated by passive air samplers mounting quartz fiber filters. The analytes were found on a regional scale. Atmospheric OPEs, semi-quantified using sampling rates of particulate-bonded PAHs, were in the range of 537-2852 pg/m³ in spring and in the range of 106-2055 pg/m³ in summer, with tris(2-chloroethyl)phosphate (TCEP) and tris(2-chloroisopropyl)phosphate as the main components. While atmospheric Di-OPs were semi-quantified using sampling rates of SO₄^2-, in the range of 22.5-5576 pg/m³ in spring and in the range of 66.9-1019 pg/m³ in summer, with di-n-butyl phosphate and diphenyl phosphate (DPHP) being the main Di-OPs. Our results indicated that OPEs were mainly distributed in the central part of the region, which might be ascribed to the distribution of industry related to OPE-containing products. In contrast, Di-OPs were scattered in the PRD, suggesting local emission from their direct industrial application. Significantly lower levels of TCEP, triphenyl phosphate (TPHP), and DPHP were detected in summer than in spring, implying that these compounds might be partitioned off particles as the temperature increased and due to possible photo-transformation of TPHP and DPHP. The results also suggested the long-distance atmospheric transportation potential of Di-OPs.

Bioaccumulation and Trophic Transfer of Organophosphate Flame Retardants and Their Metabolites in the Estuarine Food Web of the Pearl River, China

The accumulation and trophodynamics of organophosphate flame retardants (OPFRs) and their metabolites were investigated in the estuarine food web of the Pearl River, China. The mean ∑OPFR concentration among the investigated species increased in the following order: fish [431 ± 346 ng/g lipid weight (lw)] < snail (1310 ± 621 ng/g lw) < shrimp (1581 ± 1134 ng/g lw) < crab (1744 ± 1397 ng/g lw). The di-alkyl phosphates (DAPs) of di-(n-butyl) phosphate (DNBP), bis(2-butoxyethyl) phosphate (BBOEP), and diphenyl phosphate (DPHP) were the most abundant metabolites, with concentrations same as or even higher than their corresponding parent compounds. The log bioaccumulation factors for most OPFRs were lower than 3.70, and significant biomagnification was only found for trisphenyl phosphate [TPHP, with the trophic magnification factors (TMFs) > 1]. The TMFs of OPFRs, except for TPHP and tributyl phosphate had a positive correlation with lipophilicity (log K_OW, p ≤ 0.05) and a negative correlation with the biotransformation rate (log K_M, p ≤ 0.05). The mean TMF > 1 was observed for all of the OPFR metabolites based on the bootstrap regression method. The "pseudo-biomagnification" of OPFR metabolites might be attributed to the biotransformation of OPFRs in organisms at high trophic levels.

Unveiling the Occurrence and Potential Ecological Risks of Organophosphate Esters in Municipal Wastewater Treatment Plants across China

Organophosphate esters (OPEs) discharged from wastewater treatment plants (WWTPs) have attracted increasing concerns because of their potential risks to aquatic ecosystems. The identification of the structures of OPEs is a prerequisite for subsequent assessment of their environmental impacts, which could hardly be accomplished using traditional target analytical methods. In this study, we describe the use of suspect and nontarget screening techniques for identification of organophosphate triesters and diesters (tri-OPEs and di-OPEs) in the influent and effluent samples acquired from 25 municipal WWTPs across China. There are totally 33 different OPE molecules identified, 11 of which are detected in wastewater for the first time and 4 are new to the public. In all tested samples, di-OPEs account for a significant portion (53% on average) of the total OPEs (ng/L-μg/L). More importantly, most of the OPEs could not be eliminated after treatment in these WWTPs, while some of the di-OPEs even accumulate. The research priority of OPEs in the effluent based on ecological risk was also analyzed, and the results reflected a previously unrecognized exposure risk of emerging OPEs for aquatic living organisms. These findings present a holistic understanding of the environmental relevance of OPEs in WWTPs on a country scale, which will hopefully provide guidance for the upgrade of treatment protocols in WWTPs and even for the modification of governmental regulations in the future.

Source Identification of Organophosphate Esters through the Profiles in Proglacial and Ocean Sediments from Ny-Ålesund, the Arctic

Little is known about the sources and environmental behavior of organophosphate esters (OPEs) in the Arctic, especially their transformation products. The present study unprecedentedly investigated both 16 tri-OPEs and 8 di-OPEs in proglacial and ocean sediments from Ny-Ålesund, the Arctic. Mean concentrations of tri-OPEs and di-OPEs in proglacial sediments were 487 and 341 pg/g dry weight (dw), respectively, which were significantly lower than those in ocean sediments (1692 and 525 pg/g dw). Ocean sediments might be simultaneously influenced by long-range atmospheric transport (LRAT), oceanic transport, and human activities, whereas proglacial sediments, since they are isolated from human settlements, may be dominantly affected by LRAT. Such source difference was evidenced by the contamination profile of OPEs: chlorinated tri-OPEs with high environmental persistence and high LRAT were dominant in proglacial sediments (66%); however, weakly environmentally persistent and highly hydrophobic aryl tri-OPEs were dominant in ocean sediments (47%), which were plausibly from local emission sources due to their low LRAT potential. Di-OPEs in proglacial and ocean sediments were dominated by groups of parent tri-OPEs with strong photodegradability, such as alkyl (75%) and aryl (58%). A higher mean molar ratio of di-OPE/tri-OPE in the proglacial sediment (14) than that in the ocean sediment (2.2) may be related to its higher photodegradation than that of the ocean sediment.

Exploratory analysis of the association between organophosphate ester mixtures with high blood pressure of children and adolescents aged 8-17 years: cross-sectional findings from the National Health and Nutrition Examination Survey

Epidemiological studies on the effect of organophosphate esters (OPEs) on high blood pressure (BP) among children and adolescents are scant. Therefore, the main objective of the present study was to explore the effect of exposure to OPEs on high BP among children and adolescents. A total of 1340 participants were included in the current analyses. Multivariable logistic regression models were implemented to calculate odds ratios (ORs) and corresponding 95% confidence intervals (CIs) to examine the association between OPE metabolites and high BP. We also assessed the modified effect of sex, age, and overweight/obesity on this association. Furthermore, quantile g-computation (Qgcomp) and Bayesian kernel machine regression (BKMR) were exhibited to analyze the association between multiple OPE metabolite mixtures and high BP. After adjusting for covariates, the highest (vs. lowest) tertiles of bis (1-choloro-2-propyl) phosphate (BCPP), bis-2-chloroethyl phosphate (BCEP), and di-n-butyl phosphate (DBUP) were associated with 1.23 (95% CI: 0.83, 1.83), 1.27 (95% CI: 0.85, 1.92), and 1.01 (95% CI: 0.67, 1.53) odds ratios for high BP, respectively. In the Qgcomp, a quartile increase in OPE metabolite mixtures was weakly associated with an elevated risk of high BP (adjusted OR: 1.06, 95CI%: 0.81, 1.37). The results from BKMR showed a positive trend of association between OPE metabolite mixture on the risk of high BP. In conclusion, our study demonstrated that higher levels of BCPP, BCEP, and DBUP were weakly associated with high BP among US children and adolescents. Moderate evidence suggested OPE metabolite mixtures had positive joint effects on high BP. Consequently, longitudinal studies with repeated measurements are warranted to examine the relationships between multiple OPE metabolites and high blood pressure among children and adolescents.

A global survey of organophosphate esters and their metabolites in milk: Occurrence and dietary intake via milk consumption

The first global survey of organophosphate esters (OPEs) and their metabolites (mOPEs) in milk was carried out in this study. Concentrations of 21 OPEs and 9 mOPEs were measured in 178 milk samples collected from 30 countries located on 5 continents, and the ubiquity of both OPEs and mOPEs was observed in milk. Concentrations of ∑₂₁OPEs ranged from 53.3 pg/mL to 4270 pg/mL, with a median level of 367 pg/mL. The median level of ∑₉mOPEs was 153 pg/mL, with a range of 15-7440 pg/mL. No difference was observed among the levels of both ∑₂₁OPEs and ∑₉mOPEs in milk from the five continents. For the relationship between mOPEs and their parent OPEs, some pairs presented significant and positive correlations, which indicated that they shared similar sources. Estimated daily intakes (EDIs) of OPEs/mOPEs via milk consumption were calculated. Asian countries presented relatively low EDIs, and European and American countries, especially Denmark, the Netherlands, Finland and Argentina, presented high EDIs. Current daily OPE intake via milk consumption for global adult populations was far lower than the corresponding reference dose; however, considering that human intake of OPEs occurs via multiple sources, it is too early to conclude that the intake of OPEs were unable to cause health concerns.

Exposure to flame retardants in European children - Results from the HBM4EU aligned studies

Many legacy and emerging flame retardants (FRs) have adverse human and environmental health effects. This study reports legacy and emerging FRs in children from nine European countries from the HBM4EU aligned studies. Studies from Belgium, Czech Republic, Germany, Denmark, France, Greece, Slovenia, Slovakia, and Norway conducted between 2014 and 2021 provided data on FRs in blood and urine from 2136 children. All samples were collected and analyzed in alignment with the HBM4EU protocols. Ten halogenated FRs were quantified in blood, and four organophosphate flame retardants (OPFR) metabolites quantified in urine. Hexabromocyclododecane (HBCDD) and decabromodiphenyl ethane (DBDPE) were infrequently detected (<16% of samples). BDE-47 was quantified in blood from Greece, France, and Norway, with France (0.36 ng/g lipid) having the highest concentrations. BDE-153 and -209 were detected in <40% of samples. Dechlorane Plus (DP) was quantified in blood from four countries, with notably high median concentrations of 16 ng/g lipid in Slovenian children. OPFR metabolites had a higher detection frequency than other halogenated FRs. Diphenyl phosphate (DPHP) was quantified in 99% of samples across 8 countries at levels ∼5 times higher than other OPFR metabolites (highest median in Slovenia of 2.43 ng/g lipid). FR concentrations were associated with lifestyle factors such as cleaning frequency, employment status of the father of the household, and renovation status of the house, among others. The concentrations of BDE-47 in children from this study were similar to or lower than FRs found in adult matrices in previous studies, suggesting lower recent exposure and effectiveness of PBDE restrictions.

Association of organophosphate ester exposure with cardiovascular disease among US adults: Cross-sectional findings from the 2011-2018 National Health and Nutrition Examination Survey

Organophosphate esters (OPEs) are widely used as flame retardants and plasticizers worldwide. Therefore, the potentially deleterious effect of OPE on human beings deserves extensive attention. The primary objective of this present study was to untangle the relationship between OPE exposure and cardiovascular disease (CVD) among general population. Detailed information about participants' baseline characteristics, involving socioeconomic data, demographic data and key covariates was obtained from National Health and Nutrition Examination Survey (NHANES) 2011-2018. Multivariate logistic regression models with adjustment for prior-determined covariates were utilized to examine the relationship between various OPEs and CVD among US adults and calculate odd ratios (ORs) and corresponding confidence intervals (CIs). Two multi-pollutant statistical strategies (weighted quantile sum regression and Bayesian kernel machine regression) were employed to investigate the joint effect of OPE mixture on CVD. A total of 5067 participants were included in this study. In completely-adjusted logistic model, the highest tertiles of OPE metabolites were positively associated with CVD risk, while the relationships did not reach statistical significance. The weighted quantile sum (WQS) index was significantly correlated with increased prevalence of CVD (adjusted OR: 1.25; CI: 1.02, 1.53, p value = 0.032) and Diphenyl phosphate (DPHP) was the greatest contributor (31.38%). The BKMR also indicated that mixed OPE exposure associated with an increased risk of CVD. Taken together, the present study demonstrated that there were possible links between OPE exposures and increased risk of CVD, while the relationships did not reach statistical significance. Our study provided the suggestive evidence that cumulative effect of OPE mixtures on CVD. DPHP may be a major driver of this positive association. Given the limitation of cross-sectional design and relatively limited kinds of OPE metabolites, further studies are warranted to longitudinally evaluate the potential effect of a wider range of OPEs on CVD or cardiac metabolism.

The associations between renal disease severity and exposure to organophosphate flame retardants in patients with chronic kidney disease

Organophosphate flame retardants (OPFRs) are emerging and widespread environmental pollutants with potential health hazards, including nephrotoxicity. However, the exposure patterns and nephrotoxic potential of OPFRs are yet to be investigated in patients with chronic kidney disease (CKD). We conducted a cross-sectional study involving 166 patients with CKD stratified by estimated glomerular filtration rate (eGFR) and severity of proteinuria. The urinary concentrations of 10 OPFR compounds were measured to evaluate the exposure patterns. Clinical and urinary OPFR profiles were compared among subgroups to identify whether the OPFR compounds were independently correlated with eGFR and proteinuria. Additionally, lifestyle factors were compared among subgroups stratified by median concentrations of urinary OPFR compounds associated with renal disease severity. This study revealed universal exposure to OPFRs in the CKD population, with an overall urinary detection rate of 98.80 %. Furthermore, after adjusting for covariates, the urinary concentration of bis(2-chloroethyl) phosphate (BCEP) was identified as an independent predictor of lower eGFR (low vs high eGFR, odds ratio (OR) (95 % confidence interval (CI)), 1.761 (1.032-3.005) per log μg/g creatinine, p = 0.038), and the urinary concentration of bis(2-butoxyethyl) phosphate (BBOEP) was independently correlated with overt proteinuria in CKD patients (with vs without overt proteinuria, OR (95 % CI), 1.813 (1.065-3.086) per log μg/g creatinine, p = 0.028). Moreover, frequent seafood consumption was negatively correlated with urinary BCEP concentration (high vs low BCEP, OR (95 % CI), 0.455 (0.228-0.908), p = 0.025), and age was inversely associated with urinary BBOEP concentration (high vs low BBOEP, OR (95 % CI), 0.968 (0.937-0.999) per year, p = 0.048). In conclusion, our investigation highlights the extensive exposure to OPFRs and the independent association between renal disease severity and urinary BCEP/BBOEP concentrations in the CKD population, indicating the nephrotoxic potential of these pollutants.

Organophosphate tri-esters and di-esters in drinking water and surface water from the Pearl River Delta, South China: Implications for human exposure

Some organophosphate di-esters (di-OPEs) have been found to be more toxic than their respective tri-esters. The environmental occurrence of di-OPEs remains largely unclear. A total of 106 water samples, including 56 drinking water (bottled, barreled, and tap water) and 50 surface water (lake and river) samples were collected and analyzed for 10 organophosphate tri-esters (tri-OPEs) and 7 di-OPEs. The concentrations (range (median)) of ∑₇di-OPE were 2.8-22 (9.7), 1.1-5.8 (2.6), 3.7-250 (120), 13-410 (220), and 92-930 (210) ng/L in bottled water, barreled water, tap water, lake water, and river water, respectively. In all types of water samples, tris(1-chloro-2-propyl) phosphate was the dominant tri-OPE compound. Diphenyl phosphate was the predominant di-OPE compound in tap water and surface water, while di-n-butyl phosphate and bis(2-ethylhexyl) phosphate was the dominant compound in bottled water and barreled water, respectively. Source analysis suggested diverse sources of di-OPEs, including industrial applications, effluents of municipal wastewater treatment plants, degradation from tri-OPEs during production/usage and under natural environmental conditions. The non-carcinogenic and carcinogenic risks of OPEs were lower than the theoretical threshold of risk, indicating the human health risks to OPEs via drinking water consumption were negligible. More studies are needed to explore environmental behaviors of di-OPEs in the aquatic environment and to investigate ecological risks.