Triphenyl Phosphate Research Articles

Phosphorus Deficiency Promoted Hydrolysis of Organophosphate Esters in Plants: Mechanisms and Transformation Pathways.

The biotransformation of organophosphate esters (OPEs) in white lupin (Lupinus albus) and wheat (Triticum aestivum L.) was investigated in hydroponic experiments with different phosphorus (P)-containing conditions. The hydrolysis rates of OPEs followed the order of triphenyl phosphate (TPHP) > tri-n-butyl phosphate (TnBP) > tris(1,3-dichloro-2-propyl) phosphate (TDCPP). Hydrolysis of OPEs was accelerated at P-deficient conditions, and faster hydrolysis took place in white lupin than in wheat. Coincidingly, the production of acid phosphatase (ACP) in both plants was promoted, and much higher intracellular and extracellular ACPs were observed in white lupin under P-deficient conditions. In vitro experiments revealed that ACP was a key enzyme to hydrolyze OPEs. The hydrolysis rates of OPEs were significantly correlated with the Hirshfeld charges, calculated by density functional theory, of the oxygen atom in the single P-O bond. Using ultra-high-performance liquid chromatography coupled with Orbitrap Fusion mass spectrometer, 30 metabolites were successfully identified. Some of these metabolites, such as sulfate-conjugated products, hydration of cysteine-conjugated products of TPHP, and reductively dechlorinated metabolites of TDCPP, were observed for the first time in plants. It is noteworthy that OPEs may transform into many hydroxylated metabolites, and special attention should be paid to their potential environmental effects.

Pollution Characteristics of Organophosphate Esters in Frozen Soil on the Eastern Edge of Qinghai-Tibet Plateau

In this study, soil samples were collected from the eastern edge of the Qinghai Tibet Plateau in December 2019. The level and distribution characteristics of organophosphate esters (OPEs) in seasonal frozen soil were analyzed, and their sources were discussed. The results showed that the target analytes including tri-n-butyl phosphate (TnBP), tris(2-ethylhexyl) phosphate (TEHP), tributoxyethyl phosphate (TBEP), triphenyl phosphate (TPhP), tri(2-chloroethyl) phosphate (TCEP), trichloropropyl phosphate (TCPP), and tris-(2,3-dichloropropyl) phosphate (TDCPP) were detected with 100% frequency. Levels of Σ7OPEs in topsoil (0-10 cm) and sub topsoil (10-20 cm) were 146.7-348.7 ng·g-1 (mean:231.1 ng·g-1) and 206.5-333.2 ng·g-1 (mean:260.2 ng·g-1), respectively. The Σ7OPEs content level is comparable to that of urban soil,which is worthy of attention. TBEP and TDCPP were the most abundant compounds in the plateau soil. Point source emissions have significant influence on the spatial distribution of OPEs, and regional deposition of OPEs contributes to all sampling sites. The migration ability of different OPE compounds in soil was different. Stronger migration ability was observed for aromatic OPEs (TPhP) than chlorinated OPEs. Principal component analysis showed that the main sources of OPEs in plateau soil were atmospheric wet and dry deposition, manufactured consumer materials, and the release of OPEs from automobile interior decoration.

Characterization of the pyrethroid resistance mechanisms in a Blattella germanica (Dictyoptera: Blattellidae) strain from Buenos Aires (Argentina).

The use of chemical insecticides is the main control method for Blattella germanica worldwide. The prolonged and frequent use of insecticides produced the selection of insecticide-resistant individuals. The German cockroach is one of the most widespread urban pests in Argentina. In the last decades, resistance monitoring studies in this country demonstrated that there is a high prevalence of pyrethroid-resistant populations of B. germanica in the field. In this work, we studied the resistance mechanisms of a field-collected strain of B. germanica at toxicological, enzymatic, and molecular levels. A resistance ratio of 100 was obtained for the resistant strain when it was exposed to β-cypermethrin. The pretreatment with specific synergists (piperonyl butoxide and triphenyl phosphate) led to a significant increase in the toxicity of the pyrethroid, suggesting an involvement of oxidases and esterases in the detoxification of this insecticide. Moreover, esterase and oxidase activities in the resistant strain were 1.5-fold and 2-fold higher respectively, compared to the susceptible individuals. On the other hand, the voltage-gated sodium channel gene of the resistant cockroaches did not show nucleotidic substitutions in the domain II which are associated to knockdown resistance in this species. These results suggest that the main mechanism of resistance of the studied cockroaches' strain is metabolic, mainly due to an increase in the activity of oxidase and esterase enzymes. The results of this work in addition to other reports found in literature show that the extended use of a single active principle for cockroach control promotes the development of resistance leading to control failure in the field. In contrast, integrated pest management strategies include the use of different control tools in addition to chemical insecticides, which delay the appearance of resistance increasing the efficacy of pest control.

A Data-Driven Transcriptional Taxonomy of Adipogenic Chemicals to Identify White and Brite Adipogens.

Background:Chemicals in disparate structural classes activate specific subsets of the transcriptional programs of peroxisome proliferator-activated receptor- () to generate adipocytes with distinct phenotypes.Objectives:Our objectives were to a) establish a novel classification method to predict ligands and modifying chemicals; and b) create a taxonomy to group chemicals on the basis of their effects on transcriptome and downstream metabolic functions. We tested the hypothesis that environmental adipogens highly ranked by the taxonomy, but segregated from therapeutic ligands, would induce white but not brite adipogenesis.Methods:3T3-L1 cells were differentiated in the presence of 76 chemicals (negative controls, nuclear receptor ligands known to influence adipocyte biology, potential environmental ligands). Differentiation was assessed by measuring lipid accumulation. mRNA expression was determined by RNA-sequencing (RNA-Seq) and validated by reverse transcription–quantitative polymerase chain reaction. A novel classification model was developed using an amended random forest procedure. A subset of environmental contaminants identified as strong agonists were analyzed by their effects on lipid handling, mitochondrial biogenesis, and cellular respiration in 3T3-L1 cells and human preadipocytes.Results:We used lipid accumulation and RNA-Seq data to develop a classification system that a) identified agonists; and b) sorted chemicals into likely white or brite adipogens. Expression of Cidec was the most efficacious indicator of strong activation. 3T3-L1 cells treated with two known environmental ligands, tetrabromobisphenol A and triphenyl phosphate, which sorted distinctly from therapeutic ligands, had higher expression of white adipocyte genes but no difference in Pgc1a and Ucp1 expression, and higher fatty acid uptake but not mitochondrial biogenesis. Moreover, cells treated with two chemicals identified as highly ranked agonists, tonalide and quinoxyfen, induced white adipogenesis without the concomitant health-promoting characteristics of brite adipocytes in mouse and human preadipocytes.Discussion:A novel classification procedure accurately identified environmental chemicals as ligands distinct from known -activating therapeutics.Conclusion:The computational and experimental framework has general applicability to the classification of as-yet uncharacterized chemicals. https://doi.org/10.1289/EHP6886

Characterizing exposures to flame retardants, dioxins, and furans among firefighters responding to controlled residential fires.

Firefighters may encounter items containing flame retardants (FRs), including organophosphate flame retardants (OPFRs) and polybrominated diphenyl ethers (PBDEs), during structure fires. This study utilized biological monitoring to characterize FR exposures in 36 firefighters assigned to interior, exterior, and overhaul job assignments, before and after responding to controlled residential fire scenarios. Firefighters provided four urine samples (pre-fire and 3-h, 6-h, and 12-h post-fire) and two serum samples (pre-fire and approximately 23-h post-fire). Urine samples were analyzed for OPFR metabolites, while serum samples were analyzed for PBDEs, brominated and chlorinated furans, and chlorinated dioxins. Urinary concentrations of diphenyl phosphate (DPhP), a metabolite of triphenyl phosphate (TPhP), bis(1,3-dichloro-2-propyl) phosphate (BDCPP), a metabolite of tris(1,3-dichloro-2-propyl) phosphate (TDCPP), and bis(2-chloroethyl) phosphate (BCEtP), a metabolite of tris(2-chloroethyl) phosphate (TCEP), increased from pre-fire to 3-hr and 6-hr post-fire collection, but only the DPhP increase was statistically significant at a 0.05 level. The 3-hr and 6-hr post-fire concentrations of DPhP and BDCPP, as well as the pre-fire concentration of BDCPP, were statistically significantly higher than general population levels. BDCPP pre-fire concentrations were statistically significantly higher in firefighters who previously participated in a scenario (within the past 12 days) than those who were responding to their first scenario as part of the study. Similarly, firefighters previously assigned to interior job assignments had higher pre-fire concentrations of BDCPP than those previously assigned to exterior job assignments. Pre-fire serum concentrations of 2,3,4,7,8-pentachlorodibenzofuran (23478-PeCDF), a known human carcinogen, were also statistically significantly above the general population levels. Of the PBDEs quantified, only decabromodiphenyl ether (BDE-209) pre- and post-fire serum concentrations were statistically significantly higher than the general population. These results suggest firefighters absorbed certain FRs while responding to fire scenarios.

First Report on the Mechanisms of Insecticide Resistance in Field Populations of the Small Hive Beetle in Florida

The small hive beetle (Aethina tumida Murray) is a serious threat to beekeeping and crops that rely on honeybees for pollination. The small hive beetle not only causes significant damage to honeybees by feeding on pollen and honey, attacking bee brood and causing stored honey to ferment, but also might serve as a vector of diseases. In addition, the small hive beetle has developed resistance to the pyrethroid and organophosphate insecticides registered for control of honeybee pests in the United States. The development of resistance in small hive beetle populations is a great concern to the beekeeping industry; thus, there is an urgent need for strategies to manage that resistance. Therefore, we used synergist probes to determine the mechanisms of resistance in a small hive beetle population to these insecticides. Our studies on the toxicity of insecticides alone or with the synergists piperonyl butoxide (PBO) and S,S,S,-tributyl phosphorotrithionate (DEF) suggested that mixed-function oxidases and esterases were the major resistance factors to these insecticides in a studied population of the small hive beetle. In contrast, there was no synergism with diethyl maleate (DEM), triphenyl phosphate (TPP) and formamidine. Therefore, glutathione-S-transferase, carboxylesterase and target site were not involved in insecticide resistance in the small hive beetle. Rotation of classes of insecticides (with different modes of action) and metabolic synergists were suggested for the development of successful resistance management programs. To the best of our knowledge, this is the first study of the mechanisms of resistance in small hive beetle populations in Florida and suggests an urgent need for alternative control strategies for these serious pests of honeybee colonies.

Unraveling the mechanisms for persulfate-based remediation of triphenyl phosphate-contaminated soils: Complicated soil constituent effects on the formation and propagation of reactive oxygen species

The continuous accumulation of triphenyl phosphate (TPHP) in soil poses a potential threat to human health. Persulfate-based advanced oxidation processes (SR-AOPs) are promising soil remediation technologies. Naturally occurring soil constituents could interact with persulfate (PS) during soil remediation by SR-AOPs. However, the production and transformation of reactive oxygen species (ROS) by synthetic reactions between PS and different soil constituents, as well as their roles in the pollutants degradation, are still largely unknown. This study systematically investigated the generation of ROS and their roles in degradation of TPHP in soil constituents activated PS process and in soil constituents-heat (50 °C) co-activated PS process. Comprehensive studies including ROS identification, electron paramagnetic resonance analysis, and ROS-generated model systems were carried out. An appreciable degradation rate of TPHP (~21.9%) in soil-PS system and the significant discrepancy in degradation rate (69.0–97.0%) in heat-soil-PS systems with three different soils suggested that soil constituents exhibited complex effects on the activation of PS. The Fe/Mn-minerals in soil effectively activated PS and facilitated TPHP degradation. Specially, the iron redox cycle (Fe(II) ↔ Fe(III)) plays a key role in ROS generation. Small molecular soil organic matter (SOM) rapidly consumed the produced ROS which led to their mineralization, while the remaining macromolecular SOM became more hydrophilic by interaction with ROS. SO4•−, •OH, and 1O2 played major roles directly in TPHP degradation, while O2•− could not degrade TPHP directly but might promote TPHP degradation by reducing Fe(III)- to Fe(II)-minerals or converting to other ROS. This study provides new and deeper insights into the interaction between PS and soil constituents and their roles in organic pollutant degradation in contaminated soil using SR-AOPs.

New insights into the mechanism of hepatocyte apoptosis induced by typical organophosphate ester: An integrated in vitro and in silico approach

Apoptosis is one of the typical features of liver diseases, therefore molecular targets of hepatic apoptosis and regulatory mechanisms need to be further investigated. The caspases play important functions in the execution of apoptosis and many studies have focused on classical caspase-dependent cell death pathways. However, other types of cell death pathways (such as mitochondrial poly (ADP-ribose) polymerase-1 (PARP1) pathway) are suggested to be also as important as the caspase-mediated pathways in reflection of early toxic effects in hepatocytes, which requires additional research. In this work, an approach integrated in silico and in vitro was used to investigate the underlying toxicological mechanisms of hepatocyte apoptosis through the PARP1 dependent cell death pathway induced by triphenyl phosphate (TPP). Docking view showed that TPP could interact with helix αJ to affect the activation of PARP1 as a molecular initial event. In vitro assays suggested some biochemical events downstream of PARP1 activation, such as mitochondrial injury, apoptosis inducing factor (AIF) release, reactive oxygen species (ROS) production, and DNA damage. Moreover, the apoptosis was alleviated when cells were pretreated with PJ34 hydrochloride (PARP1 inhibitor), suggesting the mitochondrial PARP1 dependent pathway played a pivotal role in L02 cells apoptosis. This study indicated that PARP1 was an important molecular target in this process. And it also helped to understand the mechanism of hepatocytes apoptosis, early hepatic toxicity, and even liver diseases.

Identification and Toxicity Prediction of Biotransformation Molecules of Organophosphate Flame Retardants by Microbial Reactions in a Wastewater Treatment Plant.

Organophosphate flame retardants (OPFRs) are substances added to plastics, textiles, and furniture, and are used as alternatives to brominated flame retardants. As the use of OPFRs increases in the manufacturing industry, the concentration in the aquatic environment is also increasing. In this study, OPFRs introduced into a wastewater treatment plant (WWTP) were identified, and the toxicity of biotransformation molecules generated by the biological reaction was predicted. Tris(2-butoxyethyl) phosphate, tris(2-butoxyethyl) phosphate, and triphenyl phosphate were selected as research analytes. Chemicals were analyzed using high-resolution mass spectrometry, and toxicity was predicted according to the structure. As a result, tris(1-chloro-2-propyl) phosphate showed the highest concentration, and the removal rate of OPFRs in the WWTP was 0–57%. A total of 15 biotransformation products were produced by microorganisms in the WWTP. Most of the biotransformation products were predicted to be less toxic than the parent compound, but some were highly toxic. These biotransformation products, as well as OPFRs, could flow into the water from the WWTP and affect the aquatic ecosystem.

Neurodevelopmental toxicity assessment of flame retardants using a human DNT in vitro testing battery

Due to their neurodevelopmental toxicity, flame retardants (FRs) like polybrominated diphenyl ethers are banned from the market and replaced by alternative FRs, like organophosphorus FRs, that have mostly unknown toxicological profiles. To study their neurodevelopmental toxicity, we evaluated the hazard of several FRs including phased-out polybrominated FRs and organophosphorus FRs: 2,2′,4,4′-tetrabromodiphenylether (BDE-47), 2,2′,4,4′,5-pentabromodiphenylether (BDE-99), tetrabromobisphenol A, triphenyl phosphate, tris(2-butoxyethyl) phosphate and its metabolite bis-(2-butoxyethyl) phosphate, isodecyl diphenyl phosphate, triphenyl isopropylated phosphate, tricresyl phosphate, tris(1,3-dichloro-2-propyl) phosphate, tert-butylphenyl diphenyl phosphate, 2-ethylhexyl diphenyl phosphate, tris(1-chloroisopropyl) phosphate, and tris(2-chloroethyl) phosphate. Therefore, we used a human cell–based developmental neurotoxicity (DNT) in vitro battery covering a large variety of neurodevelopmental endpoints. Potency according to the respective most sensitive benchmark concentration (BMC) across the battery ranked from <1 μM (5 FRs), 1<10 μM (7 FRs) to the >10 μM range (3 FRs). Evaluation of the data with the ToxPi tool revealed a distinct ranking (a) than with the BMC and (b) compared to the ToxCast data, suggesting that DNT hazard of these FRs is not well predicted by ToxCast assays. Extrapolating the DNT in vitro battery BMCs to human FR exposure via breast milk suggests low risk for individual compounds. However, it raises a potential concern for real-life mixture exposure, especially when different compounds converge through diverse modes-of-action on common endpoints, like oligodendrocyte differentiation in this study. This case study using FRs suggests that human cell–based DNT in vitro battery is a promising approach for neurodevelopmental hazard assessment and compound prioritization in risk assessment.Graphical abstract

Quantification of the organophosphate flame retardant triphenylphosphate and its main metabolite in whole blood by liquid–liquid micro-extraction and liquid chromatography-tandem mass spectrometry

This work proposes a rapid, simple and accurate analytical method for quantification of the organophosphate flame retardant triphenylphosphate (TPhP) and the biomarker diphenylphosphate (DPhP) in whole blood by a simple and effective sample preparation followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) quantification. A liquid–liquid microextraction (µLLE) from 250 µL of mouse whole blood was developed and validated to quantify TPhP and DPhP. Nature of extraction solvent, grinding for cell lysis and purification step were investigated. The use of distilled solvents proved necessary to reduce and control the contamination of the ubiquitous target compounds throughout the analytical process and to maintain a stable and repeatable signal in the analytical controls.The validation was performed by matrix-matched calibration with a correction by labelled internal standards: the limit of quantification was 1 ng/mL for DPhP and 2 ng/mL for TPhP with good linearity over the range up to 48 ng/mL for each compound. Accuracy was between 92.5% and 106.7% with relative standard deviation < 20%. The µLLE-LC-MS/MS method was successfully tested during short exposures of mice to DPhP or TPhP via drinking water or by intravenous injection.

Identification of biotransformation products of organophosphate ester from various aquatic species by suspect and non-target screening approach

Organic pollutants that are introduced into the aquatic ecosystem can transform by various mechanisms. Biotransformation is an important process for predicting the remaining structures of pollutants in the ecosystem, and their toxicity. This study focused on triphenyl phosphate (TPHP), which is a commonly used organophosphate flame retardant and plasticizer. Since TPHP is particularly toxic to aquatic organisms, it is essential to understand its biotransformation in the aquatic environment. In the aquatic ecosystem, based on consideration of the producer-consumer-decomposer relationship, the biotransformation products of TPHP were identified, and their toxicity was predicted. Liquid chromatography-high resolution mass spectrometry was used for target, suspect, and non-target analysis. The obtained biotransformation products were estimated for toxicity based on the prediction model. As a result, 29 kinds of TPHP biotransformation products were identified in the aquatic ecosystem. Diphenyl phosphate was detected as a common biotransformation product through a hydrolysis reaction. In addition, products were identified by the biotransformation mechanisms of green algae, daphnid, fish, and microorganism. Most of the biotransformation products were observed to be less toxic than the parent compound due to detoxification except some products (hydroquinone, beta-lyase products, palmitoyl/stearyl conjugated products). Since various species exist in a close relationship with each other in an ecosystem, an integrated approach for not only single species but also various connected species is essential.

Bioremediation of triphenyl phosphate by Pycnoporus sanguineus: Metabolic pathway, proteomic mechanism and biotoxicity assessment

So far, no information about the biodegradability of TPhP by white rot fungi has previously been made available, herein, Pycnoporus sanguineus was used as the representative to investigate the potential of white rot fungi in TPhP bioremediation. The results suggested that the biodegradation efficiency of 5 mg/L TPhP by P. sanguineus was 62.84% when pH was adjusted to 6 and initial glucose concentration was 5 g/L. Seven biodegradation products were identified, indicating that TPhP was biotransformed through oxidative cleavage, hydroxylation and methylation. The proteomic analysis revealed that cytochrome P450s, aromatic compound dioxygenase, oxidizing species-generating enzymes, methyltransferases and MFS general substrate transporters might occupy important roles in TPhP biotransformation. Carboxylesterase and glutathione S-transferase were induced to resist TPhP stress. The biotreatment by P. sanguineus contributed to a remarkable decrease of TPhP biotoxicity. Bioaugmentation with P. sanguineus could efficiently promote TPhP biodegradation in the water-sediment system due to the cooperation between P. sanguineus and some putative indigenous degraders, including Sphingobium, Burkholderia, Mycobacterium and Methylobacterium. Overall, this study provided the first insights into the degradation pathway, mechanism and security risk assessment of TPhP biodegradation by P. sanguineus and verified the feasibility of utilizing this fungus for TPhP bioremediation applications.

Separation and recovery of rare earth from waste nickel-metal hydride batteries by phosphate based extraction-precipitation

A novel type of extraction-precipitation strategy based on phosphate was developed to recover rare earth (RE, i.e., La, Ce, Nd, and Pr) from waste nickel-metal hydride (NiMH) batteries. This method does not require saponification and organic solvents. The novel phosphates, i.e., dibenzyl phosphate (DBP), diphenyl phosphate (DPP), triphenyl phosphate (TPP) were studied as extraction-precipitants. DBP has high precipitation efficiencies for RE3+, which can reach 97.84%, 100%, 100% and 99.77%, respectively. In addition, the precipitation efficiencies of Mn2+, Co2+ and Ni2+ are less than 1.75%. DBP-RE has the largest particle size (D10 = 52.6 μm, D50 = 135.35 μm, D90 = 296.08 μm), which is much larger than the precipitations formed by NH4HCO3, H2C2O4, CaO and MgO. The larger precipitation particle sizes contribute to improving the solid-liquid separation efficiency. With 3 mol/L hydrochloric acid, the stripping efficiency of DBP-RE reaches 98.60%, and the purity of recovered RE is 99.85%. The regenerated DBP can be directly used for the recycling extraction. Therefore, the novel extraction-precipitation strategy is a green and sustainable separation method.

Organophosphorus flame retardants (OPFRs) in the seawater and sediments of the Qinzhou Bay, Northern Beibu Gulf: Occurrence, distribution, and ecological risks

The occurrence, distributions, and ecological risks of 11 organophosphate flame retardants (OPFRs) were investigated in the seawater and sediment samples from the Qinzhou Bay. The Σ11OPFRs in the surface seawater and sediments ranged from 150 to 885 ng/L and from <the limit of quantification (LOQ) to 32.2 ng/g dw, respectively, with high levels of OPFRs in the industrialized and port areas. Tris (2-chloro-propyl) phosphate (TCIPP), tris (2-chloroethyl) phosphate (TCEP), and tri-n-butyl phosphate (TNBP) were the dominant OPFRs in the surface seawater and sediments. The Σ11OPFRs concentrations in the sediment core ranged 1.2–18.6 ng/g dw and the vertical trends showed a recent increase of OPFRs emissions, especially for TNBP and triphenyl phosphate (TPHP). Risk assessment revealed that individual OPFR could pose low to medium ecological risks, but the risk from the mixture of OPFRs on aquatic organisms requires more attention.

Establishment of a Target, Suspect, and Functional Group-Dependent Screening Strategy for Organophosphate Esters (OPEs): "Into the Unknown" of OPEs in the Sediment of Taihu Lake, China.

Current environmental monitoring studies are generally confined to several target organophosphate esters (OPEs), and there is a lack of strategies for comprehensively screening all potential OPEs in environmental samples. Here, an effective and accurate strategy was developed for the target, suspect, and functional group-dependent screening of OPEs by the use of ultrahigh-performance liquid chromatography-Q Exactive hybrid quadrupole-Orbitrap high-resolution mass spectrometry (UHPLC-Q-Orbitrap HRMS), and this strategy was applied for the analysis of n = 74 sediment samples (including 23 surface sediment samples and 51 sediment core samples) collected from Taihu Lake (eastern China) in 2019. In these analyzed samples, we successfully identified n = 35 OPEs, and 23 of them were reported in this region for the first time. In addition, this strategy also presented other interesting findings, i.e., (1) OPE concentrations decreased with increasing distance from the coast of the lake; (2) the newly identified 3-hydroxyphenyl diphenyl phosphate (meta-OH-TPHP) was not statistically significantly correlated with triphenyl phosphate (TPHP; r = 0.02494, p = 0.9101) but with resorcinol bis(diphenyl phosphate) (RDP) (r = 0.9271, p < 0.0001) and three other OPEs; and (3) the summed concentrations of aryl OPEs (∑arylOPEs) in sediment core samples exhibited significantly increasing trends as the depth decreased. Collectively, this study provided an effective strategy that was successfully applied for comprehensive screening of OPEs in the sediments of Taihu Lake, and this strategy could have promising potential to be extended to other environmental matrices or samples.

Pollution Characteristics and Risk Assessment of Organophosphate Esters in Rivers and Water Body Around Taihu Lake

To explore the pollution characteristics, potential sources, and ecological and health risk of organophosphate eaters (OPEs) in the surface water of Taihu Lake, water samples from 18 surrounding rivers were collected, as well as 11 water samples from Taihu Lake. The concentrations of 13 OPEs in the water were determined using UPLC-MS/MS, and the spatial distribution of the OPEs in surface water of Taihu Lake basin was further analyzed. The results indicate that, in addition to tripropyl phosphate (TPrP), 2-ethylhexyl diphenyl phosphate (EHDPP), and tricresyl phosphate (TCrP), ten OPEs were detected in all the water samples, the total concentration (ΣOPEs) ranged from 152.5 ng·L-1 to 2524 ng·L-1, and the concentration median value was 519.2 ng·L-1. Tri(chloropropyl) phosphate (TCPP) and tri(2-chloroethyl) phosphate (TCEP) were the dominant OPEs, with the concentration ranges of 73.7-1753.9 ng·L-1 (medium value:204.6 ng·L-1) and 43.9-313.5 ng·L-1 (medium value:131.3 ng·L-1), respectively. The ΣOPEs decreased from the northwest region to the southeast, which corresponds to the economic and industrial development. The results of the source identification reveal that the wastewater discharge from electronics and textile enterprises, construction materials, and vehicular and marine traffic emissions may be the principal sources of the OPEs in Taihu Lake. The ecological risk assessment results indicate that only TCPP, tri(dichloropropyl) phosphate (TDCP), and triphenyl phosphate (TPhP) in some sites had a low risk. The health risk assessment reveals that there were no risks based on water intake, but the long-term risk of OPEs to the aquatic ecosystem and surrounding residents still need attention.

Occurrence and spatio-seasonal distribution of organophosphate tri- and di-esters in surface water from Dongting Lake and their potential biological risk

In this study, 24 surface water samples were collected from Dongting Lake, China, in the wet and dry seasons, then the concentrations, composition profiles and spatio-seasonal variations of nine organophosphate triesters (OPEs) and five organophosphate diesters (Di-OPs) were determined. Significantly higher total OPE concentrations (∑OPEs) were observed in the wet season (49.5–148 ng L−1) than in the dry season (5.00–45.7 ng L−1) suggesting higher input via tributaries discharge as well as wet deposition in the studied region. Whereas lower levels of TnBP and (triphenyl phosphate (TPHP) in wet season reflected their possible degradation under solar irradiation. Comparable levels of total Di-OPs (∑Di-OPs) were found in the wet season (3.41–13.9 ng L−1) and dry season (1.01–12.3 ng L−1). Tri(2-chloroethyl) phosphate and tris(2-chloroisopropyl) phosphate were the main OPE components, while diphenyl phosphate, di-n-butyl phosphate and bis(1,3-dichloro-2-propyl) phosphate were the main Di-OP components. High levels of OPEs and Di-OPs were found in Datong Lake suggesting possible local emissions potentially related to fishery activity in the land-locked lake. Samples at river mouths to the lake also have higher levels of target OPEs and Di-OPs, the results disclosed obvious discharges from tributaries in Hunan Province. Negligible non-carcinogenic and carcinogenic risks were determined based on the measured concentrations in source waters. A limited ecological risk aquatic organisms in the Dongting Lake was identified, with most risk from TPHP.

Full components recovery of organic matter and indium from discarded liquid crystal display panels

In the present study, organic matter and indium were fully recycled from discarded LCD panels by microwave extraction - nitrogen pyrolysis - vacuum reduction. Triphenyl phosphate, an environmentally friendly halogen-free flame retardant, was extracted from the polarizing film using microwave extraction technology. The extraction rate under optimized conditions (acetone, 55 °C, 20 min, 1:50) was 95.89%. After the microwave extraction process, the polarizing film was treated with nitrogen pyrolysis. Uncondensed pyrolysis gas/oil (mainly acetic acid) was used to prepare an environmentally friendly snow melting agent. In addition, 26.42 wt% of the pyrolytic carbon residue was obtained under the optimized conditions (350 °C, 2 °C·min−1, 0.05 L min−1, 120 min), which could be used as a reductant to recycle indium from waste LCD panels. In the vacuum reduction process, the indium conversion rate could reach 99.92% without the addition of reductant. The reaction dynamics results show that the reduction process of pyrolytic carbon and In2O3 is initially controlled by a chemical reaction, followed by a mixed control that transitions to a diffusion control. Moreover, the results of the contrast experiment show that the conversion efficiency of pyrolytic carbon to indium was comparable to that of activated carbon, and both were better than that of coke. This study can be used as a practical reference for the recycling of major components of LCD panels.

Exposure of children and mothers to organophosphate esters: Prediction by house dust and silicone wristbands

Ubiquitous human exposure to organophosphorus tri-esters (tri-OPEs) has been reported worldwide. Previous studies investigated the feasibility of using house dust and wristbands to assess human OPE exposure. We hypothesized that these two approaches could differ in relative effectiveness in the characterization of children and adult exposure. In the participants recruited from Guangzhou, South China, urinary levels of major OPE metabolites, including diphenyl phosphate (DPHP) and bis(butoxyethyl) phosphate (BBOEP), were significantly higher in children than their mothers (median 6.6 versus 3.7 ng/mL and 0.11 versus 0.06 ng/mL, respectively). The associations of dust or wristband-associated OPEs with urinary metabolites exhibited chemical-specific patterns, which also differed between children and mothers. Significant and marginally significant associations were determined between dust concentrations of triphenyl phosphate (TPHP), tris(2-butoxyethyl) phosphate (TBOEP), trimethylphenyl phosphate (TMPP), or tris(1-chloro-2-propyl) phosphate (TCIPP) and their metabolites in children urine and between dust tris(1,3-dichloroisopropyl) phosphate (TDCIPP), TPHP or TMPP and urinary metabolites in mothers. By contrast, wristbands exhibited better efficiency of predicting internal exposure to TDCIPP. While both house dust and wristbands exhibited the potential as a convenient approach for assessing long-term OPE exposure, their feasibility requires better investigations via larger-scale studies and standardized sampling protocols.