Pollution characteristics and risk assessment of organophosphate esters in aquaculture farms and natural water bodies adjacent to the Huanghe River delta

To date,little attention has been paid to the effects of organophosphate esters(OPEs)pollution on aquacultural environment and aquatic product safety.Huanghe(Yellow)River delta area is one of the largest aquaculture centers in China,where ecological security protection is crucial in the national strategy of China.To explore the pollution characteristics,bioaccumulation,and health risks of OPEs in aquaculture farms in the Huanghe River delta and natural water bodies in the adjacent seas,five species of organisms from different farm types nearby the Huanghe River delta,and the corresponding culture water and sediments were sampled in this study.The total concentrations of Σ_(13)OPEs in water,sediments,and organisms were 51.53-272.18 ng/L,52.63-63.17 ng/g dry weight(dw),and 46.82-108.90 ng/g dw,respectively.Among the five types of culture ponds,the water samples from the swimming crab and hairy crab culture ponds exhibited higher OPEs,the concentration of OPEs in the sediments from the few ponds was relatively balanced,and the OPEs in the organism from the holothurian ponds was higher.Tris(1,3-dichloro-2-isopropyl pho sphate)(TDCP)was the main contaminant in water samples and tripropyl phosphate(TPrP)in sediments and organisms.However,trisphenyl phosphate(TPhP)showed the strongest bioaccumulation ability,followed by 2-ethylhexyl diphenyl phosphate(EHDPP)and TPrP.The bioaccumulation capacities of the five species were as follows:prawn>holothurian>hairy crab>swimming crab>carp.These five types of organisms,as main seafood in human consumption,were at low risk of negative impacts of pollution.However,the risk from the mixture of organophosphate flame retardants(OPFRs)still requires more attention due to the increasing consumption and production in the world.

Fate of organophosphate esters from the Northwestern Pacific to the Southern Ocean:Occurrence,distribution,and fugacity model simulation

Eleven organophosphate esters(OPEs)in the air and seawater were investigated from the northwestern Pacific Ocean to the Southern Ocean during the 2018 Chinese 34th Antarctic Scientific Expedition.The concentration of total OPEs ranged from 164.82 to 3501.79 pg/m~3in air and from 4.54 to 70.09 ng/L in seawater.Two halogenated OPEs,tri(chloropropyl)phosphate(TCPP)and tri(2-chloroethyl)phosphate(TCEP),were generally more abundant than the non-halogenated OPEs.A levelⅢfugacity model was developed to simulate the transfer and fate of seven OPEs in the air and seawater regions of the central Ross Sea.The model results indicate that OPEs are transferred from the air to the seawater in the central Ross Sea in summer,during which the Ross Sea acts as a final OPE sink.Dry and wet deposition dominated the processes involving OPE transfer to seawater.The OPE degradation process was also found to be more pervasive in the atmosphere than in the seawater region.These findings highlights the importance of long-range transport of OPEs and their air–seawater interface behavior in the Antarctic.

Developmental toxicity assessment of neonicotinoids and organophosphate esters with a human embryonic stem cell-and metabolism-based fast-screening model

In recent years,neonicotinoids(NEOs)and organophosphate esters(OPEs)have been widely used as substitutes for traditional pesticides and brominated fame-retardants,respectively.Previous studies have shown that those compounds can be frequently detected in environmental and human samples,are able to penetrate the placental barrier,and are toxic to animals.Thus,it is reasonable to speculate that NEOs and OPEs may have potential adverse effects in humans,especially during development.We employed a human embryonic stem cell differentiation-and liver S9 fraction metabolism-based fast screening model to assess the potential embryonic toxicity of those two types of chemicals.We show that four NEO and five OPE prototypes targeted mostly ectoderm specification,as neural ectoderm and neural crest genes were down-regulated,and surface ectoderm and placode markers up-regulated.Human liver S9 fraction's treatment could generally reduce the effects of the chemicals,except in a few specific instances,indicating the liver may detoxify NEOs and OPEs.Our findings suggest that NEOs and OPEs interfere with human early embryonic development.

Short term temporal variability of selected organophosphate esters among healthy adults living in the National Capital Region of Canada

Organophosphate esters(OPEs)are used primarily as flame-retardants and plasticizers.OPEs are commonly detected in various environmental matrices,food and drinking water,and their metabolites are frequently found and quantified in urine.Potential adverse impacts on human health,including carcinogenicity,neurotoxicity,developmental and reproductive toxicity have been well documented.Urinary concentration of OPE metabolites can vary in the same individual,depending on the sampling time,thus introducing significant uncertainty in exposure assessment.The current study focusses on the assessment of short term temporal variability in adult men and women residing in Canada's Capital Region.Fifteen OPE metabolites were analyzed in 562 daily urine samples,collected every three days for five weeks from 11 volunteers.Sample extraction procedure was performed on an automated SPE and extracts analyzed using UPLC-MS/MS.In spot urine samples as well as first morning void(FMV),the detection frequency was greater than 50%for bis(2-chloroethyl)hydrogen phosphate(BCEP),bis(1-chloro-2-propyl)phosphate(BCIPP),bis(1,3-dichloro-2-propyl)phosphate(BDCIPP),diphenyl phosphate(DPHP)and bis(2,4-ditert-butylphenyl)hydrogen phosphate(B2,4DtBPP).Significant difference was observed in males and females for BCEP and BCIPP.Intra-class correlation coefficient(ICC)for creatinine corrected data for the spot urine samples ranged from 0.37 to 0.69.Good reproducibility was observed for creatinine corrected DPHP and BCIPP in both spot urine and FMV samples.More variation was observed between study participants in the spot urine samples when compared to the FMV samples.However,when considering diurnal difference there was a considerable inter-day variation in the FMV samples compared to the spot samples.The strength of the study is that the participants belonged to the same geographical location and working in the same facility,hence spatial variability did not influence the outcome of the results.

Convenient Self-Heating Instant Food Causes Significant Increasing Human Exposure to Organophosphate Esters

The self-heating lunch box(SHLB)is a kind of popular instant food in China,yet little is known about the associated chemical release risk during its heating process.In this study,we investigated organophosphate esters(OPEs)in original unheated food(UF),SHLB-heated processed food(HF)and potential OPE release from SHLB packaging materials.Significantly higher concentrations of OPEs were observed in HF(267±246 ng/g dry weight(dw))than in UF(163±211 ng/g dw)(p<0.001),suggesting an introduction of additional OPEs during heating processes.Tris(2-chloroethyl)phosphate,triethyl phosphate,and tris(2-chloroisopropyl)phosphate exhibited the highest absolute increased amounts,with 137,48.8,and 149%growth in HF than in UF,respectively.Migration testing revealed that packaging materials were rich in OPEs and can release considerable OPEs into food simulates(range,14.7-90.8 ng/g;mean,47.9±21.8).Influencing factors(temperature,contact time,oily food)on OPE migration from packaging materials to food were assessed.Higher temperature and longer contact time increased OPE contents in food simulates.Moreover,the presence of abundant OPEs in UF and significant correlations among different OPEs(p<0.05)suggested contamination happened during food processing and storage.With one SHLB meal a day,a 12-fold increase of OPE intake was observed for humans compared to those following a traditional dietary habit.In the high-exposure(95th percentile)scenario,hazard quotients of nine OPEs ranged from 0.00005 to 0.05.Our results suggested that the SHLB exposure pathway of OPEs should be particularly paid attention to in specific subpopulations that prefer this dietary habit.

Organophosphate Esters in Air and Seawater of the South China Sea:Spatial Distribution,Transport,and Air−Sea Exchange

Organophosphate esters(OPEs)have become one group of chemicals with emerging concern in the marine environment.In this work,we investigated OPEs in the air and seawater of the South China Sea in summer 2019.The concentrations of∑_(10)OPEs in the atmosphere ranged from 66 to 550 pg/m^(3),with TCIPP,TNBP,TPhP,and TEP predominating in the air.The total dissolved OPE concentrations(∑_(10)OPEs without TEP)measured in high-volume water samples ranged from 300 to 3600 pg/L,with a mean concentration of 1180±910 pg/L.TEP was measured with liquid−liquid extraction(LLE),and it showed the highest concentration(average 2000±1450 pg/L)among the selected OPEs.Total suspended matter associated OPEs accounted for less than 4.7%of the sum of OPE concentrations in seawater.Fugacity fractions and air−sea exchange fluxes showed that TCEP,TCIPP,TIBP,TEHP,TPhP,and EHDPP were favored to volatilize,TEP dominated the deposition,while TPrP and TNBP varied between volatilization and deposition.Atmospheric particle deposition fluxes ranged from 5 to 71 ng/m^(2)/day with an average of 17±15 ng/m^(2)/day.The input of∑OPEs to the entire South China Sea via atmospheric particle deposition was estimated to be 22±19 tons/year,while the net air−sea exchange fluxes of OPEs were volatilization from seawater to air with an average of 44±33 tons/year.This work suggests that air−sea exchange and atmospheric particle deposition are significant processes interfering with the transport of OPEs in the marine environment.

Organophosphate esters in sediment from Taihu Lake,China:Bridging the gap between riverine sources and lake sinks

Surface sediment samples from Taihu Lake in China and its inflow rivers,along with two lake sediment core samples,were collected and analyzed for organophosphate esters(OPEs).The concentrations of total OPEs varied from 28.60 ng/g to 158.72 ng/g(median:54.25 ng/g)in river surface sediment and from 62.57 ng/g to 326.84 ng/g(median:86.37 ng/g)in lake sediment.Tributyl phosphate(TnBP)was the predominant compound in river surface sediment,and tris(2-butoxyethyl)phosphate was predominant in lake sediment.High contamination occurred in the north-west region,which was related to the high level of urbanization and high usage of OPEs.The sediment–water partition coefficients of OPEs(log_(Koc))were calculated,showing a significant correlation with logKow(p<0.05).The concentration and composition of OPEs in two sediment cores varied due to the different sampling locations,with more OPE species found in the northern region than in the southern one.Principal component analysis and positive matrix factorization indicated that sewage discharges,vehicle emissions,and atmospheric deposition were the possible sources of OPEs in Taihu Lake sediments.Tris(1-chloro-2-propyl)phosphate,tris(2-chloroethyl)phosphate,and TnBP were the main OPEs causing ecological risks.

Organophosphate esters in water,suspended particulate matter(SPM)and sediments of the Minjiang River,China

As organic pollutants of emerging concern,organophosphate esters(OPEs)have shown toxicity to organisms after entering the water environment.However,research on OPEs in freshwater in Southwest China is very limited.The levels,distribution and partitioning behavior of OPEs in the Minjiang River and their influencing factors is still unknown.In this study,six OPEs,tri-n-butyl phosphate(Tn BP),tri(2-chloroethyl)-phosphate(TCEP),trichloropropyl phosphate(TCPP),triphenyl phosphate(TPh P),tributoxyethyl phosphate(TBEP),and tris(2-ethylhexyl)-phosphate(TEHP),were determined in surface water,suspended particle matter(SPM)and sediments of the Minjiang River.The results showed that the average concentrations of∑_(6)OPEs in surface water,SPM and sediments of the Minjiang River were 199.32±124.95 ng/L,38463.79±45641.89 ng/g dry weight(dw)and 76.45±28.00 ng/g dw,respectively.High concentrations of OPEs were detected in SPM samples,indicating that more attention should be paid to pollution in SPM.It is worth noting that the variation trend of OPEs in SPM was almost opposite to that in water but basically similar to that in sediment.The proportions of alkyl OPEs in∑_(6)OPEs increased from surface water to SPM and sediments.Alkyl OPEs were the main pollutants in SPM(10.44%–80.88%of∑_(6)OPEs,mean of 54.52%)and sediments(59.08%–81.30%of∑_(6)OPEs,mean of 68.91%),whereas chlorinated OPEs were the most abundant components in surface water(43.16%–75.99%ofδ∑_(6)OPEs,mean of 55.50%).The water-sediment partition coefficient(logKOC)of OPEs was 4.97–7.58,while the water-SPM partition coefficient was 6.71–10.00.No significant correlations were found between log KOW and logKOC.KOW was not the main factor affecting the distribution of OPEs in the Minjiang River,China.

In vitro assessment of thyroid hormone receptor activity of four organophosphate esters

Previous animal experiments have implied that organophosphate esters（OPEs） have a disruption effect on the thyroid endocrine system. However, knowledge of the toxicological mechanism remains limited. In this study, the activities of four OPEs have been characterized against the thyroid hormone（TH） nuclear receptor（TR） using two in vitro models, with the aim of evaluating their toxicity mechanisms towards the TR. The results of a TH-dependent cell proliferation assay showed that tris（2-chloro-1-（chloromethyl）ethyl）phosphate（TDCPP） could induce cell growth, while the other three OPEs had no effect. The results of a luciferase reporter gene assay revealed that all four of the OPEs tested in the current study showed agonistic activity towards TRβ, with TDCPP being the most potent one. Moreover, molecular docking revealed that all the tested OPEs could fit into the ligand binding pocket of TRβ, with TDCPP binding more effectively than the other three OPEs. Taken together, these data suggest that OPEs might disrupt the thyroid endocrine system via a mechanism involving the activation of TR.

Organophosphate esters cause thyroid dysfunction via multiple signaling pathways in zebrafish brain

Organophosphate esters(OPEs)are widespread in various environmental media,and can disrupt thyroid endocrine signaling pathways.Mechanisms by which OPEs disrupt thyroid hormone(TH)signal transduction are not fully understood.Here,we present in vivo-in vitro-in silico evidence establishing OPEs as environmental THs competitively entering the brain to inhibit growth of zebrafish via multiple signaling pathways.OPEs can bind to transthyretin(TTR)and thyroxine-binding globulin,thereby affecting the transport of TH in the blood,and to the brain by TTR through the blood-brain barrier.When GH3 cells were exposed to OPEs,cell proliferation was significantly inhibited given that OPEs are competitive inhibitors of TH.Cresyl diphenyl phosphate was shown to be an effective antagonist of TH.Chronic exposure to OPEs significantly inhibited the growth of zebrafish by interfering with thyroperoxidase and thyroglobulin to inhibit TH synthesis.Based on comparisons of modulations of gene expression with the Gene Ontology and Kyoto Encyclopedia of Genes and Genomes databases,signaling pathways related to thyroid endocrine functions,such as receptor-ligand binding and regulation of hormone levels,were identified as being affected by exposure to OPEs.Effects were also associated with the biosynthesis and metabolism of lipids,and neuroactive ligand-receptor interactions.These findings provide a comprehensive understanding of the mechanisms by which OPEs disrupt thyroid pathways in zebrafish.

Water temperature governs organophosphate ester dynamics in the aquatic food chain of Poyang Lake

Organophosphate esters(OPEs)are increasingly recognized as pervasive environmental contaminants,primarily from their extensive application in flame retardants and plasticizers.Despite their widespread presence,the intricacies of OPE bioaccumulation within aquatic ecosystems remain poorly understood,particularly the environmental determinants influencing their distribution and the bioaccumulation dynamics across aquatic food chains.Here we show that water temperature plays a crucial role in modulating the dispersion of OPE in the aquatic environment of Poyang Lake.We quantified OPE concentrations across various matrices,uncovering levels ranging from 0.198 to 912.622 ng L^(-1) in water,0.013e493.36 ng per g dry weight(dw)in sediment,0.026e41.92 ng per g wet weight(ww)in plankton,0.13e2100.72 ng per g dw in benthic invertebrates,and 0.31e3956.49 ng per g dw in wild fish,highlighting a pronounced bioaccumulation gradient.Notably,the intestines emerged as the principal site for OPE absorption,displaying the highest concentrations among the seven tissues examined.Among the various OPEs,tris(chloroethyl)phosphate was distinguished by its significant bioaccumulation potential within the aquatic food web,suggesting a need for heightened scrutiny.The propensity for OPE accumulation was markedly higher in benthic invertebrates than wild fish,indicating a differential vulnerability within aquatic biota.This study lays a foundational basis for the risk assessment of OPEs as emerging contaminants and underscores the imperative to prioritize the examination of bioaccumulation effects,particularly in benthic invertebrates,to inform future environmental safeguarding strategies.

Sex-specific effects of organophosphate ester exposure on child growth trajectories in the first two years

The connections between urinary organophosphate ester(OPE)metabolites and child growth have been identified in prior research,but there is currently a dearth of epidemiological evidence regarding the sex-specific impact of OPEs on child growth trajectories.This study enrolled 804 maternal-child pairs,and five OPE congeners were quantified in maternal serum during pregnancy.In this study,the impact of prenatal OPE exposure on child growth trajectories was assessed using linear mixed-effect models and a group-based trajectory model(GBTM),with consideration given to sex-specific effects.Fetuses were frequently exposed to OPEs in utero,and tris(2-butoxyethel)phosphate(TBEP)exhibited the highest concentration levels in maternal serum.Among male children,an increase of 2.72 ng/g lipid in TBEP concentration was associated with a 0.11-unit increase in head circumference-for-age z-score(HCAZ),and the effect was mainly concentrated at 1 and 2 months of age.Among female children,an increase of 2.72 ng/g lipid in tris(2-chloro-1-(chloromethyl)ethyl)phosphate(TDCPP)concentration was associated with a 0.15-unit increase in length-for-age z-score(LAZ)and a 0.14-unit increase in weight-for-age z-score(WAZ),and the effects were mainly concentrated at 9 months of age.For HCAZ trajectories,higher prenatal TBEP exposure was associated with higher odds for the fast growth group in male children.For the LAZ and WAZ trajectories,higher prenatal TDCPP exposure was associated with higher odds for the fast growth group in female children.The trajectory analysis approach provided insight into the complex associations between OPE exposure and child growth.

Novel biomonitoring method for determining five classes of legacy and alternative flame retardants in human serum samples

Flame retardants(FRs)are ubiquitous in environment and biota and may pose harm to human health.In recent years,concern regarding legacy and alternative FRs has been intensified due to their widespread production and increasing contamination in environmental and human matrices.In this study,we developed and validated a novel analytical method for simultaneous determination of legacy and alternative FRs,including polychlorinated naphthalenes(PCNs),short-and middle-chain chlorinated paraffins(SCCPs and MCCPs),novel brominated flame retardants(NBFRs),and organophosphate esters(OPEs)in human serum.Serum samples were prepared by liquid-liquid extraction using ethyl acetate,and purified with Oasis®HLB cartridge and Florisil–silica gel columns.Instrumental analyses were carried out using gas chromatography-triple quadrupole mass spectrometry,highresolution gas chromatography coupled with high-resolution mass spectrometry,and gas chromatography coupled with quadrupole time-of-flight mass spectrometry,respectively.The proposed method was validated for linearity,sensitivity,precision,accuracy,and matrix effects.Method detection limits for NBFRs,OPEs,PCNs,SCCPs,and MCCPs were 4.6×10^(–4)–8.6×10^(–2),4.3×10^(–3)–1.3,1.1×10^(–5)–1.0×10^(–4),1.5,and 9.0×10–1 ng/mL,respectively.Matrix spike recoveries ranged from 73%–122%,71%–124%,75%–129%,92%–126%,and 94%–126%for NBFRs,OPEs,PCNs,SCCPs,and MCCPs,respectively.The analytical method was applied for detection of real human serum.CPs were the dominant FRs in serum,indicating CPs were widely presented in human serum and should be pay more attention for their health risk.

Evaluating the blank contamination and recovery of sample pretreatment procedures for analyzing organophosphorus flame retardants in waters

Organophosphate esters（OPEs）, used as flame retardants and plasticizers, are widely present in environmental waters. Development of accurate determination methods for trace OPEs in water is urgent for understanding the fate and risk of this class of emerging pollutants. However, the wide use of OPEs in experimental materials results in blank interference, which influences the accuracy of analytical results. In the present work, blank contamination and recovery of pretreatment procedures for analysis of OPEs in water samples were systematically examined for the first time. Blank contaminations were observed in filtration membranes, glass bottles, solid phase extraction cartridges, and nitrogen blowing instruments. These contaminations could be as high as 6.4–64 ng/L per treatment. Different kinds of membranes were compared in terms of contamination levels left after common glassware cleaning, and a special wash procedure was proposed to eliminate the contamination from membranes. Meanwhile, adsorption of highly hydrophobic OPEs on the inside wall of glass bottles was found to be 42.4%–86.1%, which was the primary cause of low recoveries and was significantly reduced by an additional washing step with acetonitrile. This work is expected to provide guidelines for the establishment of analysis methods for OPEs in aqueous samples.

Current-use halogenated and organophosphorous flame retardants:A review of their presence in Arctic ecosystems

Since the ban of polybrominated diphenyl ethers(PBDEs)and hexabromocyclododecane(HBCDD),other flame retardants may be increasingly used.Thirty-one current-use halogenated(HFRs)and 24 organophosphorous flame retardants(PFRs)have been sought in Arctic ecosystems so far.Air measurements provide evidence of long-range atmospheric transport for the majority of these compounds,with much higher concentrations for PFRs than for HFRs.Some HFRs,i.e.bis(2-ethylhexyl)-tetrabromophthalate(BEH-TEBP),2-ethylhexyl-2,3,4,5-tetrabromobenzoate(EH-TBB)and hexabromobenzene(HBBz),had air concentrations comparable to those of PBDEs in some studies.Complementary data for seawater and ice indicate dry deposition of HFRs,while net volatilization from seawater was observed for some PFRs.Studies in the marine environment indicate a wide presence of HFRs in marine biota,but generally at low levels,i.e.typically lower than those of PBDEs.Exceptions exist,namely 2,4,6-tribromophenyl 2,3-dibromopropyl ether(TBP-DBPE)and decabromodiphenyl ethane(DBDPE),which were found in concentrations comparable to PBDEs in some species.The same was the case for 2,4,6-tribromophenyl allyl ether(TBP-AE)in a study from the terrestrial environment.PFRs generally had low concentrations in biota,probably due to metabolic transformation of PFR triesters,as suggested by in vitro studies.Elevated PFR concentrations occurred in some individuals,generally indicating a larger variability of PFRs in biota than found for HFRs.The commercially important tetrabromobisphenol A(TBBPA)was only detected sporadically,and only in abiotic matrices.

The utility of X-Ray fluorescence spectrometry as a tool for monitoring compliance with limits on concentrations of halogenated flame retardants in waste polymers:A critical review

This study reviews current knowledge about the presence of brominated and chlorinated organophosphate flame retardants(BFRs and Cl-OPFRs)in plastic consumer articles,with particular reference to the potential as a result of recycling,for such chemicals to unintentionally contaminate articles in which flame retardants are not required.To minimize such unintentional contamination,jurisdictions such as the EU(European Union)have introduced limits on concentrations of some BFRs in waste plastics,with articles exceeding such limits prevented from being recycled.Substantial technical and economic constraints associated with the conventional methods for determining compliance with such limit values exist,leading to less specific,but simpler,more rapid,and less expensive methods such as portable X-ray fluorescence(XRF)spectrometry being identified as possible alternatives.This paper thus examines the evidence that XRF offers a viable method for checking compliance with existing and possible future limits on BFRs and Cl-OPFRs in waste plastics and identifies future research priorities.