Organophosphorus flame retardants and plasticizers: sources, occurrence, toxicity and human exposure

Abiotic degradations of legacy and novel flame retardants in environmental and food matrices - a review

Flame retardants (FRs) are commonly added to commercial products to achieve flammability resistance. Since most of them are not chemically bonded to the materials, they could be leached to the environment during the production and disposal cycle. These FRs were categorised based on their chemical nature, including brominated, organophosphorus-, mineral- and nitrogen-based. This review summarised the abiotic degradation reactions of these four classes of FRs, with a focus on thermal and photodegradation reactions in environmental and food matrices. Only 24 papers have reported related information on abiotic degradation reactions that could be useful for predicting possible degradation pathways, and most focused on brominated FRs. Most studies also investigated the thermal degradation of FRs under high temperatures (>400 °C), which exceeds the normal cooking temperature at 100-300 °C. For photodegradation, studies have used up to five times the energy typically used in UV radiation during food processing. It is recommended that future studies investigate the fate of these FRs in foods under more realistic processing conditions, to provide a more comprehensive picture of the estimated consumption of FRs and their degradation products from foods, and facilitate a better risk assessment of the use of these novel FRs.

House dust-derived mixtures of organophosphate esters alter the phenotype, function, transcriptome, and lipidome of KGN human ovarian granulosa cells

Organophosphate esters (OPEs), used as flame retardants and plasticizers, are present ubiquitously in the environment. Previous studies suggest that exposure to OPEs is detrimental to female fertility in humans. However, no experimental information is available on the effects of OPE mixtures on ovarian granulosa cells, which play essential roles in female reproduction. We used high-content imaging to investigate the effects of environmentally relevant OPE mixtures on KGN human granulosa cell phenotypes. Perturbations to steroidogenesis were assessed using ELISA and qRT-PCR. A high-throughput transcriptomic approach, TempO-Seq, was used to identify transcriptional changes in a targeted panel of genes. Effects on lipid homeostasis were explored using a cholesterol assay and global lipidomic profiling. OPE mixtures altered multiple phenotypic features of KGN cells, with triaryl OPEs in the mixture showing higher potencies than other mixture components. The mixtures increased basal production of steroid hormones; this was mediated by significant changes in the expression of critical transcripts involved in steroidogenesis. Further, the total-OPE mixture disrupted cholesterol homeostasis and the composition of intracellular lipid droplets. Exposure to complex mixtures of OPEs, similar to those found in house dust, may adversely affect female reproductive health by altering a multitude of phenotypic and functional endpoints in granulosa cells. This study provides novel insights into the mechanisms of actions underlying the toxicity induced by OPEs and highlights the need to examine the effects of human relevant chemical mixtures.

Temporal trends of plastic additive contents in sediment cores of three French rivers (Loire, Meuse and Moselle) over the last decades

Sediment cores from three major French watersheds (Loire, Meuse and Moselle) have been dated by 137Cs and 210Pbxs from 1910 (Loire), 1947 (Meuse) and 1930 (Moselle) until the present in order to reconstruct trajectories of plastic additive contaminants including nine phthalate esters (PAEs) and seven organophosphate esters (OPEs), measured by gas chromatography-mass spectrometer (GC-MS-MS). Historical levels of ∑PAEs were higher than those of ∑OPEs in the Loire and the Moselle sediments, while ∑PAEs and ∑OPEs contents were of the same order of magnitude in the Meuse sediments. Although increases in concentrations do not evolve linearly, our results clearly indicate an increase in OPEs and PAEs concentrations from the 1950-1970 period onwards, compared with the first half of the 20th century. Our results show that, ∑OPE contents increase gradually over time in the Loire and Meuse rivers but evolve more randomly in the Moselle River. Trajectories of ∑PAEs depend on the river and no generality can be established, suggesting sedimentary reworking and/or local contamination. Data from this study allowed comparisons of contents of ∑OPEs and ∑PAEs between rivers, with ∑OPE concentrations in the Moselle River > Meuse River > Loire River, and concentrations of ∑PAEs in the Loire River > Moselle River > Meuse River. Among all PAEs, di(2-ethylhexyl) phthalate (DEHP) was the most abundant in all sediment samples, followed by diisobutyl phthalate (DiBP). Tris (2-chloroisopropyl) phosphate (TCPP) was the most abundant OPE in sediments of the three rivers. In addition, strong positive Pearson correlations were observed between organic matter (OM) parameters and OPE concentrations, and to a lesser extent, between OM parameters and PAE concentrations. This is particularly true for the Moselle River and for the Loire River, but less so for the Meuse River.

Associations between organophosphate esters and bone mineral density in adults in the United States: 2011-2018 NHANES

BACKGROUND

Organophosphate esters (OPEs) are used extensively as flame retardants and plasticizers. Laboratory studies have shown that OPEs exhibit osteotoxicity by inhibiting osteoblast differentiation; however, little is known about how OPEs exposure is associated with bone health in humans.

OBJECTIVES

We conducted a cross-sectional study to investigate the association between OPEs exposure and bone mineral density (BMD) in adults in the United States using data from the 2011-2018 National Health and Nutrition Examination Survey (NHANES).

METHODS

Multivariate linear regression models were used to assess the association between concentrations of individual OPE metabolites and BMDs. We also used the Bayesian kernel machine regression (BKMR) and quantile g-computation (qgcomp) models to estimate joint associations between OPE mixture exposure and BMDs. All the analyses were stratified according to gender.

RESULTS

A total of 3546 participants (median age, 40 years [IQR, 30-50 years]; 50.11% male) were included in this study. Five urinary OPE metabolites with a detection rate of > 50% were analyzed. After adjusting for the potential confounders, OPE metabolite concentrations were associated with decreased total-body BMD and lumbar spine BMD in males, although some associations only reached significance for bis(1-chloro-2-propyl) phosphate (BCPP), dibutyl phosphate (DBUP), and bis(2-chloroethyl) phosphate (BCEP) (β = -0.013, 95% CI: -0.026, -0.001 for BCPP and total-body BMD; β = -0.022, 95% CI: -0.043, -0.0001 for DBUP and lumbar spine BMD; β=-0.018, 95% CI: -0.034, -0.002 for BCEP and lumbar spine BMD). OPE mixture exposure was also inversely associated with BMD in males, as demonstrated in the BMKR and qgcomp models.

CONCLUSIONS

This study provides preliminary evidence that urinary OPE metabolite concentrations are inversely associated with BMD. The results also suggested that males were more vulnerable than females. However, further studies are required to confirm these findings.

Trimester-specific effect of maternal co-exposure to organophosphate esters and phthalates on preschooler cognitive development: The moderating role of gestational vitamin D status

Organophosphate esters (OPEs) and phthalate acid esters (PAEs) are prevalent endocrine-disrupting chemicals (EDCs). Humans are often exposed to OPEs and PAEs simultaneously through multiple routes. Given that fetal stage is a critical period for neurodevelopment, it is necessary to know whether gestational co-exposure to OPEs and PAEs affects fetal neurodevelopment. However, accessible epidemiological studies are limited. The present study included 2, 120 pregnant women from the Ma'anshan Birth Cohort (MABC) study. The concentrations of tris (2-chloroethyl) phosphate (TCEP), 6 OPE metabolites and 7 PAE metabolites were measured in the first, second and third trimester using ultra-performance liquid chromatography-tandem mass spectrometry (LC-MS). Cognitive development of preschooler was assessed based on the Wechsler Preschool and Primary Scale of Intelligence-Fourth Edition (WPPSI-IV) of the Chinese version. Generalized estimating equations (GEEs), restricted cubic spline (RCS) and generalized additive models (GAMs) were employed to explore the associations between individual OPE exposure and preschooler cognitive development. The quantile-based g-computation (QGC) method was used to estimate the joint effect of PAEs and OPEs exposure on cognitive development. GEEs revealed significant adverse associations between diphenyl phosphate (DPHP) (β: -0.58, 95% CI: -1.14, -0.01), bis (2-butoxyethyl) phosphate(BBOEP) (β: -0.44, 95% CI: -0.85, -0.02), bis(1-chloro-2-propyl) phosphate (BCIPP) (β: -0.81, 95%CI: -1.43, -0.20) and full-scale intelligence quotient (FSIQ) in the first trimester; additionally, TCEP and bis(2-ethylhexyl) phosphate (BEHP) in the second trimester, as well as DPHP in the third trimester, were negatively associated with cognitive development. Through the QGC analyses, mixture exposure in the first trimester was negatively associated with FSIQ scores (β: -1.70, 95% CI: -3.06, -0.34), mono-butyl phthalate (MBP), BCIPP, and DPHP might be the dominant contributors after controlling for other OPEs and PAEs congeners. Additionally, the effect of OPEs and PAEs mixture on cognitive development might be driven by vitamin D deficiency.

Concentration levels and ecological risk assessment of typical organophosphate esters in representative surface waters of a megacity

Organophosphate esters (OPEs) have been widely used as flame retardants and plasticizers in consumer and industrial products. They have been found to have numerous exposure hazards. Recently, several OPEs have been detected in surface waters around the world, which may pose potential ecological risks to freshwater organisms. In this study, the concentration, spatial variation, and ecological risk of 15 OPEs in the Beiyun and Yongding rivers were unprecedentedly investigated by the ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) and risk quotient (RQ) method. The result showed that triethyl phosphate (TEP), tri (2-chloroisopropyl) phosphate (TCPP) were the most abundant OPEs with average concentrations of 55.53 ng/L and 42.29 ng/L, respectively. The concentrations of OPEs in the Beiyun River are higher than in the Yongding River, and their levels were higher in densely populated and industrial areas. The risk assessment showed that there was insignificant from OPEs to freshwater organisms in these rivers (RQs <0.1). The risk was higher downstream than upstream, which was related to human-intensive industrial activities downstream in the Yongding River. The ecological risk of OPEs in surface waters worldwide was estimated by joint probability curves (JPCs), and the result showed that there was a moderate risk for tri (2-chloroethyl) phosphate (TCEP), a low risk for trimethyl phosphate (TMP), and insignificant for other OPEs. In addition, the QSAR-ICE-SSD model was used to calculate the hazardous concentration for 5% (HC5). This result validated the feasibility and accuracy of this model in predicting acute data of OPEs and reducing biological experiments on the toxicity of OPEs. These results revealed the ecological risk of OPEs and provided the scientific basis for environmental managers.

Occurrence, distribution, and sources of organophosphate esters (OPEs) in the air of the Indo-China Peninsula Based on a Passive Air Monitoring Network

Organophosphate esters (OPEs) are a class of emerging and ubiquitous contaminants that are attracting increasing attention, and their large-scale use as flame retardants and plasticizers has led to their pervasive presence in the environment, although their broader impacts remain unknown. In this study, 11 OPEs were measured in the atmosphere of Southeast Asia and Southwest China during 2016. The ∑11OPEs were higher in this region (78.0-1670 pg/m3, mean 458 pg/m3) than in many remote areas, lower than in developed regions, and comparable to levels in many developing country cities. Generally, the ∑11OPEs were higher in urban (105-1670 pg/m3, mean 538 pg/m3) than in suburban (78.0-1350 pg/m3, mean 388 pg/m3). Seasonal variations of OPEs in the air were more pronounced in Cambodia and Laos, especially for Triphenyl Phosphate (TPHP). Seasonal variations of ∑11OPEs in most regions correspond to changes in temperature and rainfall. Biomass burning may be also a factor in facilitating OPE emissions from biomass materials or soil into the atmosphere of Southeast Asia. The random forest analysis showed that among these, rainfall had the greatest effect on the seasonal variation of atmospheric OPE concentrations, followed by biomass burning and temperature. The inter-regional variation of ∑11OPEs in Southeast Asia was related to population and economic development in each region. Airflow trajectories indicated that the OPEs in this region were mainly from local sources. The health risk assessment revealed that the inhalation exposure risks of OPEs to the residents in the study areas were very low during the sampling period, but may be increasing.

Distribution, traceability, and risk assessment of organophosphate flame retardants in agricultural soils along the Yangtze River Delta in China

Severe pollution threatens the ecosystem and human health in the Yangtze River Delta (YRD) in China because of the rapid development of industry in this area. This study examines the types, distribution, concentration, and origin of fourteen typical organophosphate flame retardants (OPFRs) in agricultural soils within the YRD region to offer insights for pollutant control and policy-making. The total concentration of OPFRs (ΣOPFRs) varied between 79.19 and 699.58 μg/kg dry weight (dw), averaging at 209.61 μg/kg dw. Among the OPFRs detected, tributoxyethyl phosphate (TBEP) was identified as the main congener, followed by tri-n-butyl phosphate (TnBP), tris(2-chloroisopropyl) phosphate (TCPP), and trimethyl phosphate (TMP). Source analysis, conducted through correlation coefficients and PCA, indicated that OPFRs in agricultural soils within the YRD region mainly originate from emissions related to plastic products and transportation. The health risk exposure to ΣOPFRs in agricultural soil was considered negligible for farmers, with values below 1.24 × 10-2 and 1.76 × 10-9 for noncarcinogenic and carcinogenic risks, respectively. However, the ecological risk of ΣOPFRs in all the samples ranged from 0.08-1.08, indicating a medium to high risk level. The results offer a comprehensive understanding of OPFR pollution in agricultural soils in the YRD region and can be useful for pollution control that mitigates ecological and health risks in this region.

Synergistic degradation of Tris (2-Chloroethyl) Phosphate (TCEP) by US/Fenton system: Experimental, DFT calculation and toxicity evaluation

Organophosphorus esters (OPEs), exemplified by tris (2-chloroethyl) phosphate (TCEP), find extensive application in diverse industries such as construction materials, textiles, chemical manufacturing, and electronics, consequently resulting in an increased concentration of these compounds in industrial wastewater. The fundamental objective of this investigation was to examine the degradation of TCEP through the implementation of US/Fenton oxidation techniques in a solution. The findings revealed that the US/Fenton system effectively facilitated the degradation of TCEP, with the Chan kinetic model precisely elucidating the degradation process. Under optimized reaction conditions, the degradation efficiency of TCEP reached an impressive 93.18%. However, the presence of common co-existing aqueous substrates such as Cl-, HCO3-, H2PO4-, and HA hindered the degradation process. Bursting tests and electron paramagnetic resonance (EPR) studies affirmed ∙OH oxidation as the principal mechanism underlying TCEP degradation. Detailed degradation pathways for TCEP were established through the utilization of density-functional theory (DFT) calculations and GC/MS tests. Moreover, the ecotoxicological evaluation of TCEP and its intermediates was conducted using the Toxicity Estimation Software Tool (T.E.S.T.).

Investigation of alkyl, aryl, and chlorinated OPFRs in sediments from estuarine systems: Seasonal variation, spatial distribution and ecological risks assessment

Estuaries in South Africa are very important for biodiversity conservation and serve as focal points for leisure and tourism activities. The organophosphate flame retardants (OPFRs) levels in these aquatic systems haven't been documented in any studies as of yet. Due to the negative effects of persistent organic pollutants in South African estuaries, we examined the occurrence of eight OPFRs in sediments of two estuaries by studying their spatiotemporal distribution, season variation, and ecological risks. The Sundays Estuary (SDE), a semi-urbanized agricultural surrounding system, recorded an ∑8OPFR concentration in sediments that ranged from 0.71 to 22.5 ng/g dw, whereas Swartkops Estuary, a largely urbanized system, recorded a concentration that ranged from 0.61 to 119 ng/g dw. Alkyl-OPFRs were the prevalent homologue in both estuaries compared to the chlorinated and aryl groups. While TBP, TCPP, and TCrP were the most abundant compounds among the homologue groups. There was no distinct seasonal trend of ∑8OPFR concentration in either estuary, with summer and autumn seasons recording the highest concentrations in SDE and SWE, respectively. Ecological risks in the majority of the study sites for the detected compounds were at low (RQ < 0.1) and medium levels (0.1 ≤ RQ < 1) for certain species of fish, Daphnia magna and algae. However, the cumulative RQs for all the compounds had ∑RQs ≥1 for most sites in both estuaries, indicating that these organisms, if present in both estuaries, may be exposed to potential ecological concerns due to accumulated OPFR chemicals. The scope of future studies should be broadened to include research areas that are not only focus on the bioaccumulation patterns of these compounds but also find sustainable ways to reduce them from these estuarine environments.

Organophosphate esters (OPEs) in corals of the South China Sea: Occurrence, distribution, and bioaccumulation

Organophosphate esters (OPEs) have garnered significant attention in recent years. In view of the enormous ecosystem services value and severe degradation of coral reefs in the South China Sea, this study investigated the occurrence, distribution, and bioaccumulation of 11 OPEs in five coral regions: Daya Bay (DY), Weizhou Island (WZ), Sanya Luhuitou (LHT), Xisha (XS) Islands, and Nansha (NS) Islands. Although OPEs were detected at a high rate, their concentration in South China Sea seawater (1.56 ± 0.89 ng L-1) remained relatively low compared to global levels. All OPEs were identified in coral tissues, with Luhuitou (575 ± 242 ng g-1 dw) showing the highest pollution levels, attributed to intense human activities. Coral mucus, acting as a defense against environmental stresses, accumulated higher ∑11OPEs (414 ± 461 ng g-1 dw) than coral tissues (412 ± 197 ng g-1 dw) (nonparametric test, p < 0.05), and their compositional characteristics varied greatly. In the case of harsh aquatic environments, corals increase mucus secretion and then accumulate organic pollutants. Tissue-mucus partitioning varied among coral species. Most OPEs were found to be bioaccumulative (BAFs >5000 L kg-1) in a few coral tissue samples besides Triphenyl phosphate (TPHP). Mucus' role in the bioaccumulation of OPEs in coral shouldn't be ignored.

Personal environmental exposure to plasticizers and organophosphate flame retardants using silicone wristbands and urine: Patterns, comparisons, and correlations

Plasticizers (PLs) and organophosphate flame retardants (OPFRs) are ubiquitous in the environment due to their widespread use and potential for leaching from consumer products. Environmental exposure is a critical aspect of the human exposome, revealing complex interactions between environmental contaminants and potential health effects. Silicone wristbands (SWBs) have emerged as a novel and non-invasive sampling device for assessing personal external exposure. In this study, SWBs were used as a proxy to estimate personal dermal adsorption (EDdermal) to PLs and OPFRs in Belgian participants for one week; four morning urine samples were also collected and analyzed for estimated daily intake (EDI). The results of the SWBs samples showed that all the participants were exposed to these chemicals, and the exposure was found to be highest for the legacy and alternative plasticizers (LP and AP), followed by the legacy and emerging OPFRs (LOPFR and EOPFR). In urine samples, the highest levels were observed for metabolites of diethyl phthalate (DEP), di-isobutyl phthalate (DiBP) and di-n-butyl phthalate (DnBP) among LPs and di(2-ethylhexyl) terephthalate (DEHT) for APs. Outliers among the participants indicated that there were other sources of exposure that were not identified. Results showed a significant correlation between EDdermal and EDI for DiBP, tris (2-butoxyethyl) phosphate (TBOEP) and triphenyl phosphate (TPhP). These correlations indicated their suitability for predicting exposure via SWB monitoring for total chemical exposure. The results of this pilot study advance our understanding of SWB sampling and its relevance for predicting aggregate environmental chemical exposures, while highlighting the potential of SWBs as low-cost, non-invasive personal samplers for future research. This innovative approach has the potential to advance the assessment of environmental exposures and their impact on public health.

Prenatal organophosphate esters exposure and neurodevelopment trajectory in infancy: Evidence from the Shanghai Maternal-Child Pairs Cohort

BACKGROUND

Concerns remain about the neurotoxic properties of the ubiquitous organophosphate esters (OPEs), the replacement of the toxicant polybrominated diphenyl ethers.

OBJECTIVES

We examined the associations of prenatal exposure to OPEs and their mixtures with early-life neurodevelopment trajectories.

METHODS

Totally 1276 mother-child pairs were recruited from the Shanghai Maternal-Child Pairs Cohort. A high-performance liquid chromatography-triple quadrupole mass spectrometer was used to measure the levels of 7 OPEs in cord serum. Ages and Stages Questionnaires was used to examine children's neuropsychological development at 2, 6, 12, and 24 months of age. Group-based trajectory models were applied to derive the neurodevelopmental trajectories. Multiple linear regression and logistic regression model were performed to assess the relationships between OPEs exposure and neurodevelopment and trajectories. Mixtures for widely detected OPEs (n = 4) were investigated using quantile-based g-computation.

RESULTS

Tributyl phosphate (TBP), tris (2-butoxy ethyl) phosphate (TBEP), tris(1,3-dichloro-2-propyl) phosphate (TDCPP), and 2-ethylhexyl diphenyl phosphate (EHDPP), had detection rates >50 %. TDCPP had the highest median concentration (1.02 μg/L) in cord serum. EHDPP concentrations were negatively associated with scores in most domains at 12 months of age, with effect values (β) ranging from -1.89 to -0.57. EHDPP could negatively affect the total ASQ (OR = 1.07, 95 % CI: 1, 1.15) and gross-motor (OR = 1.09, 95 % CI: 1.02, 1.17) trajectory in infancy. Joint exposure to OPEs was associated with decreased scores in the total ASQ, gross-motor, fine-motor and problem-solving domain of 12-month-old infants, with β ranging from -5.93 to -1.25. In addition, the qgcomp models indicated significant positive associations between the concentrations of OPEs mixtures and risks of the persistently low group of the total ASQ, gross-motor and fine-motor development in early childhood. The impact of OPEs was more pronounced in boys.

DISCUSSION

Our findings suggested OPEs, especially EHDPP, had a persistently negative effect on neurodevelopment during the first 2 years.

Global responses to tris(1-chloro-2-propyl) phosphate and tris(2-butoxyethyl) phosphate in Escherichia coli: Evidences from biomarkers, and metabolic disturbance using GC-MS and LC-MS metabolomics analyses

Tris(1-chloro-2-propyl) phosphate (TCPP) and tris(2-butoxyethyl) phosphate (TBEP) as pollutants of emerging concern have aroused the rising attention due to their potential risks on aquatic ecosystem and public health. Nevertheless, there is a lack of toxicological mechanisms exploration of TCPP and TBEP at molecular levels. Herein, the toxicity effects and molecular mechanism of them were fully researched and summarized on Escherichia coli (E.coli). Acute exposure to them significantly activated antioxidant defense system and caused lipid peroxidation, as proved by the changes of antioxidant enzymes and MDA. The ROS overload resulted in the drop of membrane potential as well as the downregulated synthesis of ATPase, endorsing that E. coli cytotoxicity was ascribed to oxidative stress damage induced by TCPP and TBEP. The combination of GC-MS and LC-MS based metabolomics validated that TCPP and TBEP induced metabolic reprogramming in E.coli. More specifically, the responsive metabolites in carbohydrate metabolism, lipids metabolism, nucleotide metabolism, amino acid metabolism, and organic acids metabolism were significantly disturbed by TCPP and TBEP, confirming the negative effects on metabolic functions and key bioprocesses. Additionally, several biomarkers including PE(16:1(5Z)/15:0), PA(17:1(9Z)/18:2(9Z,12Z)), PE(19:1(9Z)/0:0), and LysoPE(0:0/18:1(11Z)) were remarkably upregulated, verifying that the protection of cellular membrane was conducted by regulating the expression of lipids-associated metabolites. Collectively, this work sheds new light on the potential molecular toxicity mechanism of TCPP and TBEP on aquatic organisms, and these findings using GC-MS and LC-MS metabolomics generate a fresh insight into assessing the effects of OPFRs on target and non-target aquatic organisms.

EGFR and Hippo signaling pathways are involved in organophosphate esters-induced proliferation and migration of triple-negative breast cancer cells

The widespread application of organophosphate flame retardants has led to pervasive exposure to organophosphate esters (OPEs), prompting considerable concerns regarding their potential health risk to humans. Despite hints from previous research about OPEs' association with breast cancer, their specific effects and underlying mechanisms of triple-negative breast cancer (TNBC) remain unclear. In this study, we investigated the effects of four representative OPEs on cell proliferation, cell cycle regulation, migration, and the expression of genes and proteins associated with the epidermal growth factor receptor (EGFR) and Hippo signaling pathways in TNBC (MDA-MB-231) cells. Our findings revealed that treatment with 1-25 μM triphenyl phosphate (TPHP) and tris(1,3-dichloro-2-propyl) phosphate (TDCIPP) induced TNBC cell proliferation and accelerated cell cycle progression, with upregulation in MYC, CCND1, and BRCA1 mRNA. Moreover, exposure to 1-25 μM TPHP, 10-25 μM TDCIPP, and 1-10 μM tris (2-chloroethyl) phosphate (TCEP) induced MMP2/9 mRNA expression and enhanced migratory capacity, except for 2-ethylhexyl diphenyl phosphate (EHDPP). Mechanistically, four OPEs treatments activated the EGFR-ERK1/2 and EGFR-PI3K/AKT signaling pathways by increasing the transcript of EGFR, ERK1/2, PI3K, and AKT mRNA. OPEs treatment also suppressed the Hippo signaling pathway by inhibiting the expression of MST1 mRNA and phosphorylation of LATS1, leading to the overactivation of YAP1 protein, thereby promoting TNBC cell proliferation and migration. In summary, our study elucidated that activation of the EGFR signaling pathway and suppression of the Hippo signaling pathway contributed to the proliferation, cell cycle dysregulation, and migration of TNBC cells following exposure to OPEs.

Global Trends and Hotspots in Research on the Health Risks of Organophosphate Flame Retardants: A Bibliometric and Visual Analysis

BACKGROUND

Organophosphate flame retardants (OPFRs) are compounds with a wide range of industrial and commercial applications and are mainly used as flame retardants and plasticizers. The global consumption of OPFRs has risen rapidly in recent decades, and they have been widely detected in environmental media. Unfortunately, OPFRs have been associated with many adverse health outcomes. The issue of the health risks of OPFRs is attracting increasing attention. Therefore, there is a need to review the current state of research and trends in this field to help researchers and policymakers quickly understand the field, identify new research directions, and allocate appropriate resources for further development of the OPFR health risk research field.

METHODS

This study statistically analyzed 1162 relevant publications included in the Web of Science Core Collection from 2003-2023. The internal and external features of the literature, such as publication trends, countries, authors, journals, and keywords, were quantitatively analyzed and visually presented to identify the research hotspots, compositions, and paradigms of the field and to horizontally and vertically analyze the development trends and structural evolution of the field.

RESULTS

The development of the field can be divided into three stages, and the field entered a period of rapid development in 2016. China (649 papers) is the most prolific country, followed by the United States (188 papers). The authors STAPLETON HM and WANG Y have the highest combined impact. International collaboration between countries and researchers still needs to be strengthened. Science of The Total Environment is the most frequently published journal (162 papers), and Environmental Science and Technology is the most frequently cited journal (5285 citations). Endocrine disruption, developmental toxicity, and neurotoxicity are the health effects of greatest interest.

CONCLUSIONS

Future research is expected to be multidisciplinary, and research hotspots may involve a comprehensive assessment of OPFR exposure in the population, exploration of the mechanisms of endocrine-disrupting effects and in vivo metabolic processes, and examination of the health effects of OPFR metabolites.

Flame Retardant Exposure in Vehicles Is Influenced by Use in Seat Foam and Temperature

Flame retardants (FRs) are added to vehicles to meet flammability standards, such as US Federal Motor Vehicle Safety Standard FMVSS 302. However, an understanding of which FRs are being used, sources in the vehicle, and implications for human exposure is lacking. US participants (n = 101) owning a vehicle of model year 2015 or newer hung a silicone passive sampler on their rearview mirror for 7 days. Fifty-one of 101 participants collected a foam sample from a vehicle seat. Organophosphate esters (OPEs) were the most frequently detected FR class in the passive samplers. Among these, tris(1-chloro-isopropyl) phosphate (TCIPP) had a 99% detection frequency and was measured at levels ranging from 0.2 to 11,600 ng/g of sampler. TCIPP was also the dominant FR detected in the vehicle seat foam. Sampler FR concentrations were significantly correlated with average ambient temperature and were 2-5 times higher in the summer compared to winter. The presence of TCIPP in foam resulted in ∼4 times higher median air sampler concentrations in winter and ∼9 times higher in summer. These results suggest that FRs used in vehicle interiors, such as in seat foam, are a source of OPE exposure, which is increased in warmer temperatures.

Chronic exposure to tris(1,3-dichloro-2-propyl) phosphate: Effects on intestinal microbiota and serum metabolism in rats

Tris(1,3-dichloro-2-propyl) phosphate (TDCIPP) is a widely used organophosphate ester that can adversely affect animal or human health. The intestinal microbiota is critical to human health. High-dose exposure to TDCIPP can markedly affect the intestinal ecosystem of mice, but the effects of long-term exposure to lower concentrations of TDCIPP on the intestinal flora and body metabolism remain unclear. In this study, TDCIPP was administered to Sprague-Dawley rats by gavage at a dose of 13.3 mg/kg bw/day for 90 days. TDCIPP increased the relative weight of the kidneys (P = 0.017), but had no effect on the relative weight of the heart, liver, spleen, lungs, testes, and ovaries (P > 0.05). 16 S rRNA gene sequencing revealed that long-term TDCIPP exposure affected the diversity, relative abundance, and functions of rat gut microbes. The serum metabolomics of the rats showed that TDCIPP can disrupt the serum metabolic profiles, result in the up-regulation of 26 metabolites and down-regulation of 3 metabolites, and affect multiple metabolic pathways in rat sera. In addition, the disturbed genera and metabolites were correlated. The functions of some disturbed gut microbes were consistent with the affected metabolic pathways in the sera, and these metabolic pathways were all associated with kidney disease, suggesting that TDCIPP may cause kidney injury in rats by affecting the intestinal flora and serum metabolism.

Organophosphate toxicity patterns: A new approach for assessing organophosphate neurotoxicity

Organophosphorus compounds or organophosphates (OPs) are widely used as flame retardants, plasticizers, lubricants and pesticides. This contributes to their ubiquitous presence in the environment and to the risk of human exposure. The persistence of OPs and their bioaccumulative characteristics raise serious concerns regarding environmental and human health impacts. To address the need for safer OPs, this study uses a New Approach Method (NAM) to analyze the neurotoxicity pattern of 42 OPs. The NAM consists of a 4-step process that combines computational modeling with in vitro and in vivo experimental studies. Using spherical harmonic-based cluster analysis, the OPs were grouped into four main clusters. Experimental data and quantitative structure-activity relationships (QSARs) analysis were used in conjunction to provide information on the neurotoxicity profile of each group. Results showed that one of the identified clusters had a favorable safety profile, which may help identify safer OPs for industrial applications. In addition, the 3D-computational analysis of each cluster was used to identify meta-molecules with specific 3D features. Toxicity was found to correspond to the level of phosphate surface accessibility. Substances with conformations that minimize phosphate surface accessibility caused less neurotoxic effect. This multi-assay NAM could be used as a guide for the classification of OP toxicity, helping to minimize the health and environmental impacts of OPs, and providing rapid support to the chemical regulators, whilst reducing reliance on animal testing.

Occurrence and seasonal variations of organophosphate flame retardants in air and dust from college microenvironments at Qingdao, China: Implications for student's exposure and risk assessment

Organophosphate flame retardants (OPFRs) are widely used as alternatives to brominated flame retardants in a variety of consumer products and their consumption has continuously increased in recent years. However, their concentrations and human exposures in indoor microenvironments, particularly in a university environment, have received limited attention. In this study, the concentrations and seasonal variations of 15 OPFRs were assessed in typical microenvironments of two universities, including dormitories, offices, public microenvironments (PMEs: classroom, dining hall, gymnasium and library), and laboratories on the northern coast of China. Analysis of the OPFRs in both air and dust samples indicated widespread distribution in college campuses. The average concentration of ∑15OPFRs in the winter (12,774.4 ng/g and 5.3 ng/m3 for dust and air, respectively) was higher than in the summer (2460.4 ng/g and 4.6 ng/m3 for dust and air, respectively). The dust and air samples collected from PMEs and laboratories exhibited higher concentrations of OPFRs, followed by offices and dormitories. An equilibrium was reached between dust and air in all collected microenvironments. The daily intakes of OPFRs were significantly lower than the reference dose. Dust ingestion was the primary intake pathway in the winter, while inhalation and dust ingestion were the main intake pathways in the summer. The non-carcinogenic hazard quotients fell within the range of 10-7-10-3 in both the summer and winter, which are below the theoretical risk threshold. For the carcinogenic risk, the LCR values ranged from 10-10 to 10-8, indicating no elevated carcinogenic risk due to TnBP, TCEP, and TDCP in indoor dust and air.

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

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

Occurrence, bioaccumulation and trophodynamics of organophosphate esters in the marine biota web of Laizhou Bay, Bohai Sea

The trophodynamic of organophosphate esters (OPEs) has not been known well despite their widespread occurrence in the aquatic environments. In this study, ten species of crustacean, seven species of mollusk, and 22 species of fish were collected in the Laizhou Bay (LZB) to examine the occurrence, bioaccumulation, and trophic transfer, and health risk of eight traditional OPEs and three emerging oligomeric OPEs. The results showed that total concentration of OPEs was 2.04 to 28.6 ng g-1 ww in the muscle of crustacean, mollusk, and fish and 2.62 to 60.6 ng g-1 ww in the fish gill. Chlorinated OPEs averagely contributed to over 85% of total OPEs while oligomeric OPEs averagely accounted for approximate 4%. The average log apparent bioaccumulation factor (ABAF) ranged from - 0.4 L kg-1 ww for triethyl phosphate to 2.4 L kg-1 ww for resorcinol-bis (diphenyl) phosphate. Apparent trophic magnification factors (ATMF) of individual OPE were generally less than 1, demonstrating the biodilution effect of the OPEs in the organism web of LZB. Additionally, the log ABAF and ATMF of OPEs were significantly positively correlated to their log Kow but negatively correlated to their biotransformation rate constant (BRC). Therefore, the OPEs with high Kow and low BRC tend to more accumulate in the marine organisms. The health risks associated with OPEs through the consumption of the seafood from the bay were low, even at high exposure scenario.

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

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

The dissipation of organophosphate esters mediated by ryegrass root exudate oxalic acid in soil: Analysis of enzymes activities, microorganism

Complex rhizoremediation is the main mechanism of phytoremediation in organic-contaminated soil. Low molecular weight organic acids (LMWOAs) in root exudates have been shown to increase the bioavailability of contaminants and are essential for promoting the dissipation of contaminants. The effects of root exudates on the dissipation of organophosphate esters (OPEs) in soil are unclear. Consequently, we studied the combined effects of root exudates, soil enzymes and microorganisms on OPEs (tri (1-chloro-2-propyl) phosphate (TCPP) and triphenyl phosphate (TPP)) dissipation through pot experiments. Oxalic acid (OA) was confirmed to be the main component of LMWOAs in root exudates of ryegrass. The existence of OA increased the dissipation rate of OPEs by 6.04%-25.50%. Catalase and dehydrogenase activities were firstly activated and then inhibited in soil. While, urease activity was activated and alkaline phosphatase activity was inhibited during the exposure period. More bacteria enrichment (e.g., Sphingomonas, Pseudomonas, Flavisolibacter, Pontibacter, Methylophilus and Massilia) improved the biodegradation of OPEs. In addition, the transformation paths of OPEs hydrolysis and methylation under the action of root exudates were observed. This study provided theoretical insights into reducing the pollution risk of OPEs in the soil.

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

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

The association between urinary organophosphate insecticide metabolites and erectile dysfunction in the United States

Organophosphate (OP) insecticides are the main chemicals used in agriculture for pest elimination, and they have been linked with many diseases. However, there is no literature regarding the impacts of organophosphate insecticide metabolite exposure on erectile dysfunction (ED). We aimed to evaluate the correlation between 4 urinary organophosphate insecticide metabolites and the presence of ED in a representative sample of men aged 20 and older. The dataset including a total of 555 subjects was obtained from the National Health and Nutrition Examination Survey (NHANES) 2003-2004. ED was assessed by a question from a self-report questionnaire. Weighted proportions and multivariable logistic regression analysis were utilized to examine the relationship between organophosphate insecticide metabolite exposure and ED. In multivariable logistic regression analysis, diethylphosphate (DEP) was positively correlated with ED (OR 1.07; 95% CI 1.01-1.14; P = 0.033) after full adjustment. Men in DEP tertile 4 had a significant 33% higher risk of ED than those in tertile 1. Furthermore, in a subgroup analysis, our results showed that higher DEP levels were significantly associated with ED in the young age group (20 ≤ age ≤ 39). Our study revealed a significant association between organophosphate insecticide metabolite exposure and an increased risk of ED. Moreover, the correlations were more evident in the young age group. The evaluation of urinary organophosphate insecticide metabolite exposure should be included in the risk assessment of ED. Further study to investigate the underlying mechanism, such as how long the urinary metabolite is present, whether ED is reversible in this population by lowering DEP concentrations, and how exposure to this metabolite affects erectile tissue, is warranted.

Temporal evolution of plastic additive contents over the last decades in two major European rivers (Rhone and Rhine) from sediment cores analyses

Although global plastic distribution is at the heart of 21st century environmental concerns, little information is available concerning how organic plastic additives contaminate freshwater sediments, which are often subject to strong anthropogenic pressure. Here, sediment core samples were collected in the Rhone and the Rhine watersheds (France), dated using 137Cs and 210Pbxs methods and analysed for nine phthalates (PAEs) and seven organophosphate esters (OPEs). The distribution of these organic contaminants was used to establish a chronological archive of plastic additive pollution from 1860 (Rhine) and 1930 (Rhone) until today. Sediment grain size and parameters related to organic matter (OM) were also measured as potential factors that may affect the temporal distribution of OPEs and PAEs in sediments. Our results show that OPE and PAE levels increased continuously in Rhone and Rhine sediments since the first records. In both rivers, ∑PAEs levels (from 9.1 ± 1.7 to 487.3 ± 27.0 ng g-1 dry weight (dw) ± standard deviation and from 4.6 ± 1.3 to 65.2 ± 11.2 ng g-1 dw, for the Rhine and the Rhone rivers, respectively) were higher than ∑OPEs levels (from 0.1 ± 0.1 to 79.1 ± 13.7 ng g-1 dw and from 0.6 ± 0.1 to 17.8 ± 2.3 ng g-1 dw, for Rhine and Rhone rivers, respectively). In both rivers, di(2-ethylhexyl) phthalate (DEHP) was the most abundant PAE, followed by diisobutyl phthalate (DiBP), while tris (2-chloroisopropyl) phosphate (TCPP) was the most abundant OPE. No relationship was found between granulometry and additives concentrations, while organic matter helps explain the vertical distribution of PAEs and OPEs in the sediment cores. This study thus establishes a temporal trajectory of PAEs and OPEs contents over the last decades, leading to a better understanding of historical pollution in these two Western European rivers.

Tris(2-chloroethyl) phosphate (TCEP) exposure inhibits the epithelial-mesenchymal transition (EMT), mesoderm differentiation, and cardiovascular development in early chicken embryos

Tris(2-chloroethyl) phosphate (TCEP) is an organophosphorus flame retardant used worldwide and has been detected in the tissues and eggs of wild birds. Our previous study reported that exposure to TCEP induced developmental delay and cardiovascular dysfunction with attenuated heart rate and vasculogenesis in early chicken embryos. This study aimed to investigate the molecular mechanisms underlying the cardiovascular effects of TCEP on chicken embryos using cardiac transcriptome analysis and to examine whether TCEP exposure affects epithelial-mesenchymal transition (EMT) and mesoderm differentiation during gastrulation. Transcriptome analysis revealed that TCEP exposure decreased the expression of cardiac conduction-related genes and transcription factors on day 5 of incubation. In extraembryonic blood vessels, the expression levels of genes related to fibroblast growth factor (FGF) and vascular endothelial growth factor (VEGF) were significantly reduced by TCEP exposure and vasculogenesis was suppressed. TCEP exposure also attenuated Snail family transcriptional repressor 2 (SNAI2) and T-box transcription factor T (TBXT) signaling in the chicken primitive streak, indicating that TCEP inhibits EMT and mesoderm differentiation during gastrulation at the early developmental stage. These effects on EMT and mesoderm differentiation may be related to subsequent phenotypic defects, including suppression of heart development and blood vessel formation.

Assessing developmental neurotoxicity of emerging environmental chemicals using multiple in vitro models: A comparative analysis

Newly synthesized chemicals are being introduced into the environment without undergoing proper toxicological evaluation, particularly in terms of their effects on the vulnerable neurodevelopment. Thus, it is important to carefully assess the developmental neurotoxicity of these novel environmental contaminants using methods that are closely relevant to human physiology. This study comparatively evaluated the potential developmental neurotoxicity of 19 prevalent environmental chemicals including neonicotinoids (NEOs), organophosphate esters (OPEs), and synthetic phenolic antioxidants (SPAs) at environment-relevant doses (100 nM and 1 μM), using three commonly employed in vitro neurotoxicity models: human neural stem cells (NSCs), as well as the SK-N-SH and PC12 cell lines. Our results showed that NSCs were more sensitive than SK-N-SH and PC12 cell lines. Among all the chemicals tested, the two NEOs imidaclothiz (IMZ) and cycloxaprid (CYC), as well as the OPE tris(1,3-dichloro-2-propyl) phosphate (TDCIPP), generated the most noticeable perturbation by impairing NSC maintenance and neuronal differentiation, as well as promoting the epithelial-mesenchymal transition process, likely via activating NF-κB signaling. Our data indicate that novel NEOs and OPEs, particularly IMZ, CYC, and TDCIPP, may not be safe alternatives as they can affect NSC maintenance and differentiation, potentially leading to neural tube defects and neuronal differentiation dysplasia in fetuses.

Distribution and Risk Assessment of Organophosphate Esters in Agricultural Soils and Plants in the Coastal Areas of South China

Organophosphate esters (OPEs) are frequently used as flame retardants and plasticizers in various commercial products. While initially considered as substitutes for brominated flame retardants, they have faced restrictions in some countries due to their toxic effects on organisms. We collected 37 soil and crop samples in 20 cities along the coast of South China, and OPEs were detected in all of them. Meanwhile, we studied the contamination and potential human health risks of OPEs. In soil samples, the combined concentrations of eight OPEs varied between 74.7 and 410 ng/g, averaging at 255 ng/g. Meanwhile, in plant samples, the collective concentrations of eight OPEs ranged from 202 to 751 ng/g, with an average concentration of 381 ng/g. TDCIPP, TCPP, TCEP, and ToCP were the main OPE compounds in both plant and soil samples. Within the study area, the contaminants showed different spatial distributions. Notably, higher OPEs were found in coastal agricultural soils in Guangdong Province and crops in the Guangxi Zhuang Autonomous Region. The results of an ecological risk assessment show that the farmland soil along the southern coast of China is at high or medium ecological risk. The average non-carcinogenic risk and the carcinogenic risk of OPEs in soil through ingestion and dermal exposure routes are within acceptable levels. Meanwhile, this study found that the dietary intake of OPEs through food is relatively low, but twice as high as other studies, requiring serious attention. The research findings suggest that the human risk assessment indicates potential adverse effects on human health due to OPEs in the soil-plant system along the coast of South China. This study provides a crucial foundation for managing safety risks in agricultural operations involving OPEs.

Organophosphorus flame retardants in fish from the middle reaches of the Yangtze River: Tissue distribution, age-dependent accumulation and ecological risk assessment

Two fish species from the middle reaches of the Yangtze River, China, were sampled to investigate the occurrence, tissue distribution, age-dependent accumulation and ecological risk assessment of 24 organophosphorus flame retardants (OPFRs). Seventeen OPFRs were detected in tissue samples with a total concentration ranging from not detected (ND) to 1092 ng g-1 dw. Cl-OPFRs were predominant in all tissues (mean: 145 ng g-1 dw, median: 72.9 ng g-1 dw) and the concentrations of OPFRs in brain were the greatest (crucian carp: 525 ng g-1 dw, silver carp: 56.0 ng g-1 dw) compared with the other three organs (e.g., liver, muscle and gonad). Furthermore, the total concentrations of OPFRs in crucian carp tissues were significantly greater than those in silver carp (P < 0.01). Age-dependent accumulation of OPFRs was observed in the two fish species, but the accumulation profiles in the two fish species were different. Ecological risk assessment demonstrated that both fish species were at medium to high risk, and TDCIPP was a main contributor (>50%).

Organophosphate ester additives and microplastics in benthic compartments from the Loire estuary (French Atlantic coast)

We report the first empirical confirmation of the co-occurrence of organophosphate esters (OPEs) additives and microplastics (MPs) in benthic compartments from the Loire estuary. Higher median concentrations of MPs (3387 items/kg dw), ∑13tri-OPEs (12.0 ng/g dw) and ∑4di-OPEs (0.7 ng/g dw) were measured in intertidal sediments with predominance of fine particles, and under higher anthropogenic pressures, with a general lack of seasonality. Contrarily, Scrobicularia plana showed up to 4-fold higher ∑tri-OPE concentrations in summer (reaching 37.0 ng/g dw), and similar spatial distribution. Polyethylene predominated in both compartments. Tris(2-ethylhexyl) phosphate (TEHP), its degradation metabolite (BEHP) and tris-(2-chloro, 1-methylethyl) phosphate (TCIPP) were the most abundant OPEs in sediments, while TCIPP predominated in S. plana. The biota-sediment accumulation factors suggest bioaccumulation potential for chlorinated-OPEs, with higher exposure in summer. No significant correlations were generally found between OPEs and MPs in sediments suggesting a limited role of MPs as in-situ source of OPEs.

Distribution and adsorption-desorption of organophosphate esters from land to sea in the sediments of the Beibu Gulf, South China Sea: Impact of seagoing river input

Organophosphate esters (OPEs) have been a class of emerging environmental contaminants. However, studies on their environmental behavior, specifically their adsorption-desorption behavior between sediment and seawater in estuarine and coastal areas, remain limited. To address this gap, our study focused on investigating the levels and behavior of 11 OPEs in sediment samples collected from the Beibu Gulf, South China Sea, encompassing estuaries and coastal regions. The total concentrations of 11 OPEs (Σ11OPEs) in the sediments exhibit a significant decrease in summer, both in seagoing rivers (4.67 ± 2.74 ng/g dw) and the coastal zone (5.11 ± 3.71 ng/g dw), compared to winter levels in seagoing rivers (8.26 ± 4.70 ng/g dw) and the coastal zone (7.71 ± 3.83 ng/g dw). Chlorinated OPEs dominated the sediments, constituting 63 %-76 % of the total. Particularly, port and mariculture areas showed the highest levels of OPEs. Through load estimation analysis, it was revealed that the sedimentary OPEs in Qinzhou Bay (221 ± 128 kg) had the highest load, with input from the Qin River identified as a significant source. Chlorinated OPEs showed a trend of desorption from sediments to the water column with increasing salinity, emphasizing the crucial role of land-based OPEs input through suspended particulate matter in rivers as a pathway to the ocean. The impact of strong flow in estuarine environments was highlighted, as it can scour sediments, generate suspended sediments, and release OPEs into the water bodies. Additionally, the results of the ecological risk assessment indicated that most of the OPEs posed low-risk levels. However, attention is warranted for the contamination levels of some chlorinated OPEs, emphasizing the need for ongoing monitoring and assessment.

Do the same chlorinated organophosphorus flame retardants that cause cytotoxicity and DNA damage share the same pathway?

Organophosphorus flame retardants (OPFRs) have been frequently detected with relatively high concentrations in various environmental media and are considered emerging environmental pollutants. However, their biological effect and underlying mechanism is still unclear, and whether chlorinated OPFRs (Cl-OPFRs) cause adverse outcomes with the same molecular initial events or share the same key events (KEs) remains unknown. In this study, in vitro bioassays were conducted to analyze the cytotoxicity, mitochondrial impairment, DNA damage and molecular mechanisms of two Cl-OPFRs. The results showed that these two Cl-OPFRs, which have similar structures, induced severe cellular and molecular damages via different underlying mechanisms. Both tris(2-chloroethyl) phosphate (TCEP) and tris(1-chloro-2-propyl) (TCPP) induced oxidative stress-mediated mitochondrial impairment and DNA damage, as shown by the overproduction of intracellular reactive oxygen species (ROS) and mitochondrial superoxide. Furthermore, the DNA damage caused by TCPP resulted in p53/p21-mediated cell cycle arrest, as evidenced by flow cytometry and real-time PCR. At the cellular and molecular levels, TCPP increased the sub-G1 apoptotic peak and upregulated the p53/Bax apoptosis pathway, possibly resulted in apoptosis associated with its stronger cytotoxicity. Although structurally similar to TCPP, TCEP did not induce mitochondrial impairment and DNA damage by the same KEs. These results provide insight into the toxicity of Cl-OPFRs with similar structures but different mechanisms, which is of great significance for constructing adverse outcome pathways or determining intermediate KEs.

Organophosphate esters in edible marine fish: Tissue-specific distribution, species-specific bioaccumulation, and human exposure

Although growing evidences have proved the wide presence of organophosphate esters (OPEs) in marine environments, information on the tissue- and species-specific accumulation characteristics of these emerging pollutants in wild marine fish and the associated human exposure risks are currently lacking. Eleven OPEs were comprehensively investigated for their occurrence and tissue accumulation in 15 marine fish species and their living environment matrices (seawater and sediment) from the Beibu Gulf. The OPE concentrations were statistically higher in the liver (17.6-177 ng/g ww, mean 90.9 ± 52.1 ng/g ww) than those of muscle tissues (2.04-22.9 ng/g ww, mean 10.6 ± 5.6 ng/g ww). Tris (phenyl) phosphate (TPHP) was the most predominant OPE congeners in fish liver, and tris(2-chloropropyl) phosphate (TCIPP) and tris(2-chloroethyl) phosphate (TCEP) were dominant OPEs in the muscle. The results suggested different OPE profiles occurred between the tissues. The median logarithmic bioaccumulation factors (BAFs) of TPHP in the muscle and liver, and TCEP in muscle were higher than the regulatory benchmark value (BCF >3.7), indicating very strong bioaccumulation. Carnivorous benthic fish appear to potentially accumulate TPHP, while pelagic and omnivory fish tend to accumulate TCIPP and TCEP. Except for proteins and phospholipids, no significant relationships were found between OPE levels and other biological properties of the studied fish. The results implied that the species-specific accumulation of OPEs mainly attributed to habitat and feeding habit rather than the difference of biochemical composition among species. Metabolism may have a significant effect on the bioaccumulation of OPEs in marine fish. The dietary risks of OPEs for consumers in different age groups ranged from 2.02 × 10-4 to 3.01 × 10-3, indicating relatively low human exposure risks from fish consumption.

Insights into the occurrence, spatial distribution, and ecological implications of organophosphate triesters in surface sediments from polluted urban rivers across China

Organophosphate triesters (tri-OPEs) are a kind of widespread contaminants in the world, particularly in China, which is a major producer and user of tri-OPEs. However, tri-OPE pollution in urban river sediments in China remains unclear. In current work, we carried out the first nationwide investigation to comprehensively monitor 10 conventional and five emerging tri-OPEs in sediments of 173 black-odorous urban rivers throughout China. Concentrations of 10 conventional and five emerging tri-OPEs were 3.8-1240 ng/g dw (mean: 253 ng/g dw) and 0.21-1107 ng/g dw (68 ng/g dw), respectively, and significantly differed among the cities sampled but generally decreased from Northeast and East China to Central and West China. These spatial patterns suggest that tri-OPE pollution was mainly from local sources and was controlled by the industrial and economic development levels in these four areas, as indicated by the significant correlations between tri-OPE concentrations and gross domestic production, gross industrial output, and daily wastewater treatment capacity. Although the tri-OPE composition varied spatially at different sites, which indicated different tri-OPE input patterns, it was commonly dominated by tris(2-chloroethyl) phosphate, tris(2-ethylhexyl) phosphate, and tris(1-chloro-2-propyl) phosphate (conventional tri-OPEs) and bisphenol A-bis(diphenyl phosphate) and isodecyl diphenyl phosphate (emerging tri-OPEs). A risk assessment indicated that tri-OPEs in most sampling sediments had a low to moderate risk to aquatic organisms.

Association between organophosphate flame retardant exposure and lipid metabolism: data from the 2013-2014 National Health and Nutrition Examination Survey

Organophosphate flame retardants (OPFRs) are emerging environmental pollutants that can be detected in water, dust, and biological organisms. Certain OPFRs can disrupt lipid metabolism in animal models and cell lines. However, the effects of OPFRs on human lipid metabolism remain unclear. We included 1,580 participants (≥20 years) from the 2013-2014 National Health and Nutrition Examination Survey (NHANES) to explore the relationship between OPFR exposure and lipid metabolism biomarkers. After adjusting for confounding factors, results showed that one-unit increases in the log levels of diphenyl phosphate (DPhP) (regression coefficient = -5.755; S.E. = 2.289; p = 0.023) and log bis-(1-chloro-2-propyl) phosphate (BCPP) (regression coefficient = -4.637; S.E. = 2.019; p = 0.036) were negatively associated with the levels of total cholesterol (TC) in all participants. One-unit increases in the levels of DPhP (regression coefficient = -2.292; S.E. = 0.802; p = 0.012), log bis (1,3-dichloro-2-propyl) phosphate (BDCPP) (regression coefficient = -2.046; S.E. = 0.825; p = 0.026), and log bis-2-chloroethyl phosphate (BCEP) (regression coefficient = -2.604; S.E. = 0.704; p = 0.002) were negatively associated with the levels of high-density lipoprotein cholesterol (HDL-C). With increasing quartiles of urine BDCPP levels, the mean TC levels significantly decreased in all participants (p value for trend = 0.028), and quartile increases in the levels of DPhP (p value for trend = 0.01), BDCPP (p value for trend = 0.001), and BCEP (p value for trend<0.001) were negatively corelated with HDL-C, with approximately 5.9, 9.9, and 12.5% differences between the upper and lower quartiles. In conclusion, DPhP, BDCPP, and BCEP were negatively related to HDL-C concentration, whereas DPhP and BCPP levels were negatively associated with TC level. Thus, exposure to OPFRs may interfere with lipid metabolism.

The transport and distribution of novel brominated flame retardants (NBFRs) and organophosphate esters (OPEs) in soils and moss along mountain valleys in the Himalayas

Although the Himalayas act as a natural barrier, studies have demonstrated that certain traditional persistent organic pollutants (POPs) can be transported into the Tibetan Plateau (TP) through the mountain valleys. Herein, we selected five mountain valleys in the Himalayas to investigate novel flame retardants (NFRs), as representative novel POPs, their concentration, distribution, transport behavior, potential sources and ecological risk. The results revealed that total concentrations of 7 novel brominated flame retardants (NBFRs) ranged from 4.89 to 2853 pg/g dry weight (dw) in soil and from not detected (ND) to 4232 pg/g dw in moss. Additionally, total concentrations of 10 organophosphate esters (OPEs) ranged from ND to 84798 pg/g dw in soil. Among the NFRs, decabromodiphenylethane (DBDPE) and tri-phenyl phosphate (TPhP) were the predominant compounds. NBFRs and OPEs concentrations were slightly higher than those in the polar regions. The correlation between different compounds and altitude varies in different areas, indicating that the NFRs distribution in the mountain valleys result from a combination of long-range transport and local sources. The ecological risk assessment using risk quotient (RQs) revealed that TPhP and tris (2-chloroisopropyl) phosphate (TCIPP) exhibited medium or high risks at some sites. This study sheds light on the transport pathways and environmental behaviors of the NFRs in the valleys and highlights the need for increased attention to the ecological risks posed by OPEs in the TP.

Tracing Organophosphate Ester Pollutants in Hadal Trenches─Distribution, Possible Origins, and Transport Mechanisms

Unraveling the mysterious pathways of pollutants to the deepest oceanic realms holds critical importance for assessing the integrity of remote marine ecosystems. This study tracks the transport of pollutants into the depths of the oceans, a key step in protecting the sanctity of these least explored ecosystems. By analyzing hadal trench samples from the Mariana, Mussau, and New Britain trenches, we found the widespread distribution of organophosphate ester (OPE) flame retardants but a complex transport pattern for the OPE in these regions. In the Mariana Trench seawater column, OPE concentrations range between 17.4 and 102 ng L-1, with peaks at depths of 500 and 4000 m, which may be linked to Equatorial Undercurrent and topographic Rossby waves, respectively. Sediments, particularly in Mariana (422 ng g-1 dw), showed high OPE affinity, likely due to organic matter serving as a transport medium, influenced by "solvent switching", "solvent depletion", and "filtering processes". Amphipods in the three trenches had consistent OPE levels (29.1-215 ng g-1 lipid weight), independent of the sediment pollution patterns. The OPEs in these amphipods appeared more linked to surface-dwelling organisms, suggesting the influence of "solvent depletion". This study highlights the need for an improved understanding of deep-sea pollutant sources and transport, urging the establishment of protective measures for these remote marine habitats.

Exposure of male adult zebrafish (Danio rerio) to triphenyl phosphate (TPhP) induces eye development disorders and disrupts neurotransmitter system-mediated abnormal locomotor behavior in larval offspring

Triphenyl phosphate (TPhP) is a widely used organophosphorus flame retardant, which has become ubiquitous in the environment. However, little information is available regarding its transgenerational effects. This study aimed to investigate the developmental toxicity of TPhP on F1 larvae offspring of adult male zebrafish exposed to various concentrations of TPhP for 28 or 60 days. The findings revealed significant morphological changes, alterations in locomotor behavior, variations in neurotransmitter, histopathological changes, oxidative stress levels, and disruption of Retinoic Acid (RA) signaling in the F1 larvae. After 28 and 60 days of TPhP exposure, the F1 larvae exhibited a myopia-like phenotype with pathological alterations in the lens and retina. The genes involved in the RA signaling pathway were down-regulated following parental TPhP exposure. Swimming speed and total distance of F1 larvae were significantly reduced by TPhP exposure, and long-term exposure to environmental levels of TPhP had more pronounced effects on locomotor behavior and neurotransmitter levels. In conclusion, TPhP induced histological and morphological alterations in the eyes of F1 larvae, leading to visual dysfunction, disruption of RA signaling and neurotransmitter systems, and ultimately resulting in neurobehavioral abnormalities. These findings highlight the importance of considering the impact of TPhP on the survival and population reproduction of wild larvae.

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

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

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.

The influence of emerging atmospheric organophosphorus flame retardants from land source emissions on the East China Sea

Organophosphate flame retardants (OPFRs) pose a new challenge to the marine environment due to their toxicity and persistence. This study explores the contributions of OPFR emissions from different land sources and sectors to its contamination of the East China Sea (ECS) using a novel atmospheric transport model（ChnMETOP）for POPs and a marine food web model. The results show that the major land sources causing OPFR pollution in the ECS were situated in Yangtze River Delta (YRD) and middle reach areas of China's Yangtze River, confirming that source proximity made most significant contributions to OPFR pollution in the ECS. Among those OPFR emission sectors, industrial emissions accounted for the highest modeled OPFR levels in the seawaters, followed by the OPFR usage process in textile, plastic, and rubber products. Assessment of bioaccumulation of OPFR in the marine food web of the ECS and the potential risk in commercial fish consumers reveals lower exposure risk via dietary fish ingestion. However, the risk might increase if OPFRs are continuously bioaccumulated in the biotic and released into the abiotic marine environment. This study simultaneously identified both the source locations and emission sectors, thereby providing important policy implications in mitigating OPFR pollution in the ECS marine environment.

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

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

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.

Organophosphate esters in the urban atmosphere of Thessaloniki city, Greece

The occurrence of organophosphate esters (OPEs) in the atmosphere of the urban area of Thessaloniki city, Greece was studied. OPEs were determined in particulate matter (PM2.5) and precipitation during the period 2020-2021. ∑OPEs in rainwater ranged from 520 to 4719 ng L-11 (mean: 1662 ng L-1) with tris (2-butoxyethyl) phosphate (TBOEP) and tris (1-chloro-2-propyl) phosphate (TClPP) being the most abundant compounds. TBOEP and TClPP as well as triphenylphosphine oxide (TPPO) and tris (chloroethyl) phosphate (TCEP) were the dominant OPEs in PM2.5. Concentrations of ∑OPEs in PM2.5ranged from 2.82 to 13.3 ng m-3 (mean: 5.93 ng m-3). Wet deposition fluxes of OPEs were estimated and air mass back trajectories were used to elucidate possible source profiles. An overall low health risk for local population via inhalation of OPEs was revealed.

Tris(1,3-dichloro-2-propyl) phosphate induces endoplasmic reticulum stress and mitochondrial-dependent apoptosis in mouse spermatocyte GC-2 cells

Tris(1,3-dichloro-2-propyl) phosphate (TDCIPP) is a frequently detected organophosphorus flame retardants (OPFRs) in various environmental media, and has been evidenced as reproductive toxicity. However, its adverse effects on spermatogenic cells are unknown. In this study, mouse spermatocyte GC-2spd (GC-2) cells were selected as an in vitro model, and the impact of mitochondrial structure and function, endoplasmic reticulum (ER) stress, cell apoptosis and the related molecular mechanisms were investigated. Our study indicated that cell viability was decreased significantly in a dose-dependent manner after TDCIPP treatment with the half lethal concentration (LC50) at 82.8 μM, 50.0 μM and 39.6 μM for 24 h, 48 h and 72 h, respectively. An apoptosis was observed by Annexin V-FITC/PI stain. In addition, fragmentation of mitochondrial structure, an increase of mitochondrial membrane potential (MMP), reduction of cellular adenosine triphosphate (ATP) content, release of cytochrome c and activation of Caspase-3 and Caspase-9 activity implicated that Caspase-3 dependent mitochondrial pathway might play a key role in the process of GC-2 cell apoptosis. Furthermore, ER stress induction was convinced by altered morphology of ER and up-regulation of ER targeting genes, including (Bip, eIF2α, ATF4, XBP1, CHOP, ATF6 and Caspase-12). Taken together, these results demonstrate that both mitochondrial apoptotic pathways and ER stress apoptotic pathways might play important roles in the process of apoptosis in GC-2 cells induced by TDCIPP treatment. Therefore, the potential reproductive toxicity of TDCIPP should not be ignored.

Role of inflammatory lipid and fatty acid metabolic abnormalities induced by plastic additives exposure in childhood asthma

Lipid metabolism play an essential role in occurrence and development of asthma, and it can be disturbed by phthalate esters (PAEs) and organophosphate flame retardants (OPFRs). As a chronic inflammatory respiratory disease, the occurrence risk of childhood asthma is increased by PAEs and OPFRs exposure, but it remains not entirely clear how PAEs and OPFRs contribute the onset and progress of the disease. We have profiled the serum levels of PAEs and OPFRs congeners by liquid chromatography coupled with mass spectrometry, and its relationships with the dysregulation of lipid metabolism in asthmatic, bronchitic (acute inflammation) and healthy (non-inflammation) children. Eight PAEs and nine OPFRs congeners were found in the serum of children (1 - 5 years old) from Shenzhen, and their total median levels were 615.16 ng/mL and 17.06 ng/mL, respectively. Moreover, the serum levels of mono-methyl phthalate (MMP), tri-propyl phosphate (TPP) and tri-n-butyl phosphate (TNBP) were significant higher in asthmatic children than in healthy and bronchitic children as control. Thirty-one characteristic lipids and fatty acids of asthma were screened by machine-learning random forest model based on serum lipidome data, and the alterations of inflammatory characteristic lipids and fatty acids including palmitic acids, 12,13-DiHODE, 14,21-DiHDHA, prostaglandin D2 and LysoPA(18:2) showed significant correlated with high serum levels of MMP, TPP and TNBP. These results imply PAEs and OPFRs promote the occurrence of childhood asthma via disrupting inflammatory lipid and fatty acid metabolism, and provide a novel sight for better understanding the effects of plastic additives on childhood asthma.

Patterns of urinary organophosphate ester metabolite trajectories in children: the HOME Study

BACKGROUND

Organophosphate esters (OPEs) have replaced flame retardant polybrominated diphenyl ethers as flame retardants in consumer products, but few longitudinal studies have characterized childhood OPE exposure.

OBJECTIVE

We aimed to examine the exposure pattern of urinary OPE metabolites in children.

METHODS

We quantified three urinary OPE metabolites five times in children (1, 2, 3, 5, 8 years) from 312 mother-child pairs in the Health Outcomes and Measures of the Environment (HOME) Study, a prospective pregnancy and birth cohort in Cincinnati, Ohio, USA. We examined the associations of average maternal OPE metabolite concentrations with OPE metabolite concentrations in childhood, characterized childhood OPE trajectories with latent class growth analysis (LCGA), and examined factors related to trajectory membership.

RESULTS

Bis(2-chloroethyl) phosphate (BCEP) had the lowest median concentrations over time (0.66-0.97 mg/L) while the median concentrations of bis(1,3-dichloro-2-propyl) phosphate (BDCIPP) increased with age (1.44-3.80 mg/L). The median concentrations of diphenyl phosphate (DPHP) fluctuated between 1.96 and 2.69 mg/L. Intraclass correlation coefficients for urinary metabolites measured at five time points indicated high variability within individuals (0.13-0.24). Average maternal urinary BCEP and BDCIPP were associated with concentrations in early childhood. Maternal education, the birth year of the child, and having a carpet in the main activity room were associated with BCEP and BDCIPP trajectory while none of the factors were associated with DPHP trajectory.

SIGNIFICANCE

The trajectory analysis showed different patterns of urinary OPE metabolite concentrations, suggesting the need to collect multiple samples to adequately reflect OPE exposure.

IMPACT STATEMENT

In this well-established cohort, we evaluated the patterns of urinary OPE metabolites in children ages 1-8 years. The number of repeated measures over childhood has not been achieved in prior studies. Our results suggested the high variability of urinary OPE metabolites within individuals. Maternal metabolite concentrations during pregnancy were related to child concentrations at ages 1-3 years. BCEP, BDCIPP, and DPHP demonstrated different trajectories in children, which suggests that multiple samples may be required to capture OPE exposure patterns in childhood.

Mechanism of interaction between ascorbic acid and soil iron-containing minerals for peroxydisulfate activation and organophosphorus flame retardant degradation

Soil constituents may play an important role in peroxydisulfate (PDS)-based oxidation of organic contaminants in soil. Iron-containing minerals (Fe-minerals) have been found to promote PDS activation for organics degradation. Our study found that ascorbic acid (H2A) could enhance PDS activation by soil Fe-minerals for triphenyl phosphate (TPHP) degradation. Determination and characterization analyses of Fe fractions showed that H2A could induce the reductive dissolution of solid Fe-minerals and the increasing of oxygen vacancies/hydroxyl groups content on Fe-minerals surface. The increasing of divalent Fe (Fe(II)) accelerated PDS activation to generate reactive oxygen species (ROS). Electron paramagnetic resonance (EPR) and quenching studies showed that sulfate radicals (SO4•-) and hydroxyl radicals (HO•) contributed significantly to TPHP degradation. The composition and content of Fe-minerals and soil organic matter (SOM) markedly influenced ROS transformations. Surface-bond and structural Fe played the main role in the production of Fe(II) in reaction system. The high-concentration SOM could result in ROS consumption and degradation inhibition. Density functional theory (DFT) studies revealed that H2A is preferentially adsorbed at α-Fe2O3(012) surface through Fe-O-C bridges rather than hydrogen bonds. After absorption, H atoms on H2A may further be migrated to adjacent O atoms on the α-Fe2O3(012) surface. With the transformation of H atoms to the α-Fe2O3(012) surface, the Fe-O-C bridge is broken and one electron is transferred from the O to Fe atom, inducing the reduction of trivalent Fe (Fe(III)) atom. MS/MS2 analysis, HPLC analysis, and toxicity assessment demonstrated that TPHP was transformed to less toxic 4-hydroxyphenyl diphenyl phosphate (OH-TPHP), diphenyl hydrogen phosphate (DPHP), and phenyl phosphate (PHP) through phenol-cleavage and hydroxylation processes, and even be mineralized in reaction system.