A critical review of human exposure to organophosphate esters with a focus on dietary intake

Exploring organophosphate ester contamination and distribution in food: A meta-analysis

This study examines the food safety risk of organophosphate esters (OPEs) by analyzing data from 23 studies with 14,915 data points. We found EDP contamination highest in cereals, dairy, and meats, and TEHP most prevalent in vegetables and fruits, with contamination levels reaching 4.54 ng/g and 1.46 ng/g, respectively. Food processing influences OPE contamination through complex and multifaceted, akin to a "double-edged sword.", as meta-analysis and Principal Component Analysis (PCA) revealed. Estimated Dietary Intakes (EDI) identified vegetables and cereals as primary OPE sources, contributing 33.3% and 23.8% of total intake, with EDI values of 44.74 ng/kg bw/day and 32.25 ng/kg bw/day, respectively. Current exposure levels are within U.S. EPA safety thresholds (HQ < < 1), but the heightened risk to infants and children necessitates revising safety standards and ongoing monitoring.

Exposure to organophosphate esters among Inuit adults of Nunavik, Canada

Halogenated organophosphate esters (OPEs) are increasingly used as flame retardants to replace polybrominated diphenyl ethers (PBDEs), which have been phased out due to their confirmed persistence, toxicity, and ability to undergo long range atmospheric transport. Non-halogenated OPEs are primarily used as plasticizers. While human exposure to PBDEs in the Canadian Arctic is well documented, it is not the case for OPEs. To assess the exposure to OPEs in Inuit living in Nunavik (northern Québec, Canada), we measured 16 metabolites of halogenated and non-halogenated OPEs in pooled urine samples from the last population health survey conducted in Nunavik, the Qanuilirpitaa? 2017 Inuit Health Survey (Q2017). Urine samples (n = 1266) were pooled into 30 pools by sex (female; male), age groups (16-19; 20-29; 30-39; 40-59; 60+ years old) and regions (Hudson Bay; Hudson Strait; Ungava Bay). Q2017 geometric means and 95 % confidence intervals were compared with data from the Canadian Health Measures Survey Cycle 6 (2018-2019) (CHMS). Halogenated OPEs were systematically detected and generally found at higher concentrations than non-halogenated OPEs in both Q2017 and CHMS. Furthermore, urinary levels of BCIPP and BDCIPP (halogenated) were lower in Q2017 compared to CHMS while concentrations of DPhP, DpCP and DoCP (non-halogenated) were similar between Q2017 and CHMS. Across the 16 metabolites measured in Q2017, BCIPHIPP (halogenated) had the highest levels (geometric mean: 1.40 μg/g creatinine). This metabolite was not measured in CHMS and should be included in future surveys. Overall, our results show that Inuit in Nunavik are exposed to lower or similar OPEs levels than the rest of the general Canadian population suggesting that the main current exposure to OPEs may be from consumer goods containing flame retardants and imported from the south rather than long-range atmospheric transport to the Arctic.

Occurrence, spatial distribution and ecological risk assessment of Organophosphate Esters in surface water and sediments from the Ravi River and its tributaries

Organophosphate esters (OPEs) are widely used as substitutes for brominated flame retardants and characterized as emerging contaminants. Due to their toxicity and persistent nature, OPEs are becoming a matter of greater concern worldwide. However, information about the pollution profile of OPEs and associated ecological risks is still scarce in environmental matrices of the South Asian region, particularly Pakistan. Hence, the current study was conducted to investigate the occurrence, spatial distribution patterns, ecological risks and riverine flux of 10 organophosphate esters in surface water and sediments of Ravi River and its four tributaries. The concentrations of ∑10OPEs were in the range of 19.2 - 105 ng/L, with the dominance of chlorinated-OPEs (51 %) in surface water, whereas in case of sediments, the ∑10OPEs concentrations ranged from 20.7 to 149 ng/g dw, with high abundance of non - chlorinated alkyl-OPEs, which contributed about 56 % to total OPE concentration. The correlation analysis signified a strong positive relation of OPEs with TOC (p < 0.05, R = 0.76) in sediments; and in addition to this, field-based LogKoc values were estimated to be higher than predicted LogKoc. Moreover, a significantly positive correlation (p < 0.05, R = 0.88) was observed between LogKoc and LogKow, implying that hydrophobicity plays a significant role in OPE distribution in different environmental matrices. The global comparison revealed that contamination status of OPEs in the present study was comparatively lower than other regional findings, furthermore, principal component analysis suggested vehicular emissions, industrial discharges, household supplies and atmospheric deposition as main sources of OPEs occurrence in current study region. Furthermore, the riverine flux of ∑10OPEs was estimated to be 0.68 tons/yr and the ecological risk assessment indicated that all OPEs, except EHDPP and TCrP, showed negligible or insignificant ecological risks for aquatic organisms.

Profiling population-wide exposure to environmental chemicals: A case study of naphthalene

Long-term exposure to environmental chemicals can detrimentally impact human health, and understanding the relationship between age distribution and levels of external and internal exposure is crucial. Nonetheless, existing methods for assessing population-wide exposure across age groups are limited. To bridge this research gap, we introduced a modeling approach designed to assess both chronic external and internal exposure to chemicals at the population level. The external and internal exposure assessments were quantified in terms of the average daily dose (ADD) and steady-state blood concentration of the environmental chemical, respectively, which were categorized by age and gender groups. The modeling process was presented within a spreadsheet framework, affording users the capability to execute population-wide exposure analyses across a spectrum of chemicals. Our simulation outcomes underscored a salient trend: younger age groups, particularly infants and children, exhibited markedly higher ADD values and blood concentrations of environmental chemicals compared to their older counterparts. This observation is due to the elevated basal metabolic rate per unit of body weight characteristic of younger individuals, coupled with their diminished biotransformation kinetics of xenobiotics within their livers. These factors collectively contribute to increased intake rates of environmental chemicals per unit of body weight through air and food consumption, along with heightened bioaccumulation of these chemicals within their bodies (e.g., blood). Furthermore, we augmented the precision of the external and internal exposure assessment by incorporating the age distribution across the population. The simulation outcomes unveiled that, to estimate the central tendency of the population's exposure levels, employing the baseline value group (age group 21-30) or the surrogate age of 25 serves as a simple yet dependable approach. However, for comprehensive population protection, our recommendation aligns with conducting exposure assessments for the younger age groups (age group 0-11). Future studies should integrate individual-level exposure assessment, analyze vulnerable population groups, and refine population structures within our developed model.

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.

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

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

Bioaccessibility of halogenated flame retardants and organophosphate esters in settled dust: Influences of specific dust matrices from informal e-waste and end-of-life vehicle processing areas in Vietnam

Bioaccessibility of halogenated flame retardants (HFRs) and organophosphorus esters (OPEs) is necessarily investigated to provide more accurate risk assessment and information about absorption behavior of these pollutants. In this study, total and bioaccessible concentrations of HFRs (including legacy and alternative substances) and OPEs were determined in settled dust samples collected from Vietnamese e-waste and end-of-life vehicle (ELV) processing areas. Concentrations of both HFRs and OPEs were significantly higher in the e-waste dust than ELV dust. Bioavailability of HFRs and OPEs in dust was determined by using an in vitro assay with human-simulated digestive fluids, dialysis membrane, and Tenax® TA sorptive sink. Bioaccessibility of HFRs was markedly lower than that of OPEs, which could be largely due to higher hydrophobicity of HFRs compared to OPEs. Bioaccessibility of almost hydrophobic compounds were markedly lower in the e-waste dust (containing micronized plastic debris) than in the ELV dust (containing oily materials), suggesting the influence of specific dust matrices on pollutant bioaccessibility. Although the daily uptake doses of selected HFRs and OPEs from dust were markedly higher in the e-waste sites compared to the ELV sites, the direct exposure risk was not significant. Our results suggest that bioaccessibility can partly explain the differences between dust and uptake profiles, which may relate to accumulation profiles of HFRs and OPEs in human samples.

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

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

Association between exposure to chemical mixtures and epigenetic ageing biomarkers: Modifying effects of thyroid hormones and physical activity

Evidence on the effects of internal chemical mixture exposures on biological age is limited. It also remains unclear whether hormone homeostasis and lifestyle factors can modify such a relationship. Based on the Biomarkers for Air Pollutants Exposure (BAPE) study, which involved healthy older adults aged 60-69 years in China, we found that chemical mixture exposures, including metals, polycyclic aromatic hydrocarbons (PAHs), per- and polyfluoroalkyl substances (PFASs), phthalates (PAEs), and organophosphate esters (OPEs), were significantly associated with shortened DNAmTL and accelerated SkinBloodClock, in which PFASs and OPEs in blood were the primary contributors to DNAmTL, while metals and PAEs had relatively higher contributions in urine. Furthermore, lower levels of thyroxin appeared to exacerbate the adverse effects of environmental chemicals on epigenetic ageing but relatively higher levels of physical activity had the beneficial impact. These findings may have important implications for the development of healthy ageing strategy and aged care policy, particularly in light of the global acceleration of population ageing.

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

BACKGROUND

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Emerging organophosphite and organophosphate esters in takeaway food and the implications for human exposure

Takeaway food has become a prominent component of the diet in urban areas of China, especially for young people. Although dietary intake is a major pathway to contaminants for human exposure, studies on emerging organophosphite antioxidants (OPAs) and organophosphate esters (OPEs) in food are scarce. Here, we investigated four OPAs and 19 OPEs in takeaway foods (n = 99) and paired takeaway food packaging (n = 50) in China. AO168=O (mean: 14.9 ng/g ww), TPPO (mean: 1.05 ng/g ww), and TCIPP (mean: 0.579 ng/g ww) were dominant in the takeaway food. Some OPEs had significant correlations in takeaway food. Emerging OPAs and OPEs in takeaway food varied significantly depending on the packaging materials and food types. AO168 and AO168=O were widespread in the paired takeaway food packaging. The migration efficiencies of emerging OPAs and OPEs were low in takeaway food packaged in aluminum foil. Although the actual contamination of emerging OPAs and OPEs in takeaway food significantly differed from those of in food simulants migrated from paired takeaway food packaging, the results imply that food itself and takeaway food packaging are potential contamination sources of emerging OPAs and OPEs in takeaway food. The average estimated dietary intakes of emerging OPAs and OPEs were 465 ng/kg body weight (bw)/day and 91.9 ng/kg bw/day, respectively. The exposure risk of emerging OPAs and OPEs through takeaway food intake is low in China.

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.

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.

Occurrence and Health Risk Assessment of Phthalates in Municipal Drinking Water Supply of a Central Indian City

In this study, the occurrence of phthalates in the municipal water supply of Nagpur City, India, was studied for the first time. The study aimed to provide insights into the extent of phthalate contamination and identify potential sources of contamination in the city's tap water. We analyzed fifteen phthalates and the total concentration (∑15phthalates) ranged from 0.27 to 76.36 µg L-1. Prominent phthalates identified were di-n-butyl phthalate (DBP), di-isobutyl phthalate (DIBP), benzyl butyl phthalate (BBP), di (2-ethylhexyl) phthalate (DEHP), di-n-octyl phthalate (DNOP), and di-nonyl phthalate (DNP). Out of the fifteen phthalates analyzed, DEHP showed the highest concentration in all the samples with the median concentration of 2.27 µg L-1, 1.39 µg L-1, 1.83 µg L-1, 2.02 µg L-1, respectively in Butibori, Gandhibaag, Civil Lines, and Kalmeshwar areas of the city. In 30% of the tap water samples, DEHP was found higher than the EPA maximum contaminant level of 6 µg L-1. The average daily intake (ADI) of phthalates via consumption of tap water was higher for adults (median: 0.25 µg kg-1 day-1) compared to children (median: 0.07 µg kg-1 day-1). The hazard index (HI) calculated for both adults and children was below the threshold level, indicating no significant health risks from chronic toxic risk. However, the maximum carcinogenic risk (CR) for adults (8.44 × 10-3) and children (7.73 × 10-3) was higher than the threshold level. Knowledge of the sources and distribution of phthalate contamination in municipal drinking water is crucial for effective contamination control and management strategies.

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

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

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.

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.

Myriophyllum Biochar-Supported Mn/Mg Nano-Composites as Efficient Periodate Activators to Enhance Triphenyl Phosphate Removal from Wastewater

Transition metals and their oxide compounds exhibit excellent chemical reactivity; however, their easy agglomeration and high cost limit their catalysis applications. In this study, an interpolation structure of a Myriophyllum verticillatum L. biochar-supported Mn/Mg composite (Mn/Mg@MV) was prepared to degrade triphenyl phosphate (TPhP) from wastewater through the activating periodate (PI) process. Interestingly, the Mn/Mg@MV composite showed strong radical self-producing capacities. The Mn/Mg@MV system degraded 93.34% TPhP (pH 5, 10 μM) within 150 min. The experimental results confirmed that the predominant role of IO3· and the auxiliary ·OH jointly contributed to the TPhP degradation. In addition, the TPhP pollutants were degraded to various intermediates and subsequent Mg mineral phase mineralization via mechanisms like interfacial processes and radical oxidation. DFT theoretical calculations further indicated that the synergy between Mn and Mg induced the charge transfer of the carbon-based surface, leading to the formation of an ·OH radical-enriched surface and enhancing the multivariate interface process of ·OH, IO3, and Mn(VII) to TPhP degradation, resulting in the further formation of Mg PO4 mineralization.

Global patterns of human exposure to flame retardants indoors

To fill the knowledge gaps regarding the global patterns of human exposure to flame retardants (FRs) (i.e., brominated flame retardants (BFRs) and organophosphorus flame retardants (OPFRs)), data on the levels and distributions of FRs in external and internal exposure mediums, including indoor dust, indoor air, skin wipe, serum and urine, were summarized and analysed. Comparatively, FR levels were relatively higher in developed regions in all mediums, and significant positive correlations between FR contamination and economic development level were observed in indoor dust and air. Over time, the concentration of BFRs showed a slightly decreasing trend in all mediums worldwide, whereas OPFRs represented an upward tendency in some regions (e.g., the USA and China). The occurrence levels of FRs and their metabolites in all external and internal media were generally correlated, implying a mutual indicative role among them. Dermal absorption generally contributed >60% of the total exposure of most FR monomers, and dust ingestion was dominant for several low volatile compounds, while inhalation was found to be negligible. The high-risk FR monomers (BDE-47, BDE-99 and TCIPP) identified by external exposure assessment showed similarity to the major FRs or metabolites observed in internal exposure mediums, suggesting the feasibility of using these methods to characterize human exposure and the contribution of indoor exposure to the human burden of FRs. This review highlights the significant importance of exposure assessment based on multiple mediums for future studies.

Triphenyl phosphate exposure impairs colorectal health by altering host immunity and colorectal microbiota

Colorectal diseases such as colorectal cancer (CRC) and inflammatory bowel disease (IBD) have become one of the most common public health concerns worldwide due to the increasing incidence. Environmental factors are one of the important causes of colorectal diseases, as they can affect the intestinal barrier function, immune response and microbiota, causing intestinal inflammation and tumorigenesis. Triphenyl phosphate (TPHP), a widely used organophosphorus flame retardant that can leach and accumulate in various environmental media and biota, can enter the human intestine through drinking water and food. However, the effects of TPHP on colorectal health have not been well understood. In this study, we investigated the adverse influence of TPHP exposure on colorectal cells (in vitro assay) and C57BL/6 mice (in vivo assay), and further explored the potential mechanism underlying the association between TPHP and colorectal disease. We found that TPHP exposure inhibited cell viability, increased apoptosis and caused G1/S cycle arrest of colorectal cells. Moreover, TPHP exposure damaged colorectal tissue structure, changed immune-related gene expression in the colorectal transcriptome, and disrupted the composition of colorectal microbiota. Importantly, we found that TPHP exposure upregulated chemokine CXCL10, which was involved in colorectal diseases. Our study revealed that exposure to TPHP had significant impacts on colorectal health, which may possibly stem from alterations in host immunity and the structure of the colorectal microbial community.

Uptake mechanism, translocation, and transformation of organophosphate esters in water hyacinth (Eichhornia crassipes): A hydroponic study

Owing to their dominant wastewater origin, bioavailability, and toxicity, the occurrence and behavior of organophosphate esters (OPEs) in aquatic systems have attracted considerable attention over the past two decades. Aquatic plants can accumulate and metabolize OPEs in water, thereby playing an important role in their behavior and fate in waterbodies. However, their uptake, translocation and transformation mechanisms in plants remain incompletely characterized. We investigated the accumulation and transformation of OPEs in water hyacinth (Eichhornia crassipes) through a series of hydroponic experiments using three representative OPEs, tris(2-chloroethyl) phosphate (TCEP), tris(2-butoxyethyl) phosphate (TBEP), and triphenyl phosphate (TPP). These OPEs can not only be adsorbed onto and enter plant roots via passive diffusion pathways, which are facilitated by anion channels and/or aquaporins, but also can return to the solution when concentration gradients exist. After entry, hydrophilic TCEP showed a dominant distribution in the cell sap, strong acropetal transportability, and rapid translocation rate, whereas hydrophobic TPP was mostly retained in the root cell wall and therefore demonstrated weak acropetal transportability; TBEP with moderate hydrophilicity remained in the middle. All these OPEs can be transformed into diesters, which presented higher proportions in the cell sap and therefore have stronger acropetal transferability than their parent OPEs. TCEP exhibits the lowest biodegradability, followed by TPP and TBEP. These OPEs exerted apparent effects on plant growth, photosynthesis, and the diversity and composition of the rhizosphere microbial community.

Perinatal triphenyl phosphate exposure induces metabolic dysfunctions through the EGFR/ERK/AKT signaling pathway: Mechanistic in vitro and in vivo studies

Triphenyl phosphate (TPhP), a widely used organophosphate-flame retardant, is ubiquitously found in household environments and may adversely affect human health. Evidence indicates that TPhP exposure causes metabolic dysfunctions in vivo; however, the underlying mechanism of such adverse effects has not been comprehensively investigated. Herein, we utilized two in vitro models including mouse and human preadipocytes to delineate adipogenic mechanisms of TPhP. The results revealed that both mouse and human preadipocytes exposed to TPhP concentration-dependently accumulated more fat through a significant upregulation of epidermal growth factor receptor (EGFR). We demonstrated that TPhP significantly promoted adipogenesis through the activation of EGFR/ERK/AKT signaling pathway as evident by a drastic reduction in adipogenesis of preadipocytes cotreated with inhibitors of EGFR and its major effectors. Furthermore, we confirmed the mechanism of TPhP-induced metabolic dysfunctions in vivo. We observed that male mice perinatally exposed to TPhP had a significant increase in adiposity, hepatic triglycerides, insulin resistance, plasma insulin levels, hypotension, and phosphorylated EGFR in gonadal fat. Interestingly, an administration of a potent and selective EGFR inhibitor significantly ameliorated the adverse metabolic effects caused by TPhP. Our findings uncovered a potential mechanism of TPhP-induced metabolic dysfunctions and provided implications on toxic metabolic effects posed by environmental chemicals.

Accumulation of organophosphorus pollutants in adipose tissue of obese women - metabolic alterations

Organophosphorus pesticides (OPPs) and organophosphate esters (OPEs) are organophosphorus compounds created as substitutes for persistent environmental pollutants, namely organochlorines pesticides and brominated flame retardants, respectively. However, there is evidence that organophosphorus compounds are also widespread across the environment and have adverse effects on biota. In humans, OPPs and OPEs were reported to be carcinogenic, neurotoxic, hepatotoxic, nephrotoxic, amongst others. As lipophilic compounds, these accumulate in fat tissues as adipose tissue. Yet biomonitoring studies and analytical methodologies to assess these compounds in the human body are scarce, particularly in adipose tissue. In this study, the presence of six OPPs and seven OPEs was determined in samples of subcutaneous adipose tissue (scAT) and visceral adipose tissue (vAT) from 188 adult obese women. OPPs and OPEs were quantified by gas chromatography (GC) flame photometric detection and confirmed in GC tandem mass spectrometry. The detection frequencies ranged between 0.5-1.6% and 48-53%, respectively for OPPs and OPEs. Organophosphorus pollutants were present in both adipose tissues and median concentrations were 0.008 ± 0.020 μg/g scAT and 0.009 ± 0.020 μg/g vAT. A total of 32 Spearman's correlations were found between organophosphorus pollutants concentrations in adipose tissue and several biochemical parameters (18 positive and 14 negative). Our results show that anthropometric and hormonal parameters, cholesterol, glycaemia, macrominerals, urea and sedimentation velocity might be influenced by the presence of these compounds. The presence of organophosphorus pollutants in the environmental and their possible effect on female metabolic processes is concerning. Particularly because presently OPEs usage is not controlled or limited by any regulation. More studies are needed to fully understand these pollutants behaviour and hazard effects on human health, biota, and the environment so control regulations can be drawn to prevent and lessen their effects.

Triphenyl phosphate disrupts placental tryptophan metabolism by activating MAOA/ROS/NFκB

Triphenyl phosphate (TPhP) is an organophosphate flame retardant widely distributed in the environment. The neurodevelopmental toxicity of TPhP has been observed in animals and humans. Previously, we found that prenatal TPhP exposure disturbed placental tryptophan metabolism, impaired neurodevelopment in male offspring, and induced abnormal neurobehavior; however, the underlying mechanisms are unknown. In this study, using the trophoblast cell line JEG-3, we found that TPhP altered gene and protein expression in the tryptophan metabolism pathway, inhibited the tryptophan-serotonin pathway, and activated the tryptophan-kynurenine pathway. Meanwhile, TPhP induced oxidative stress by activating monoamine oxidase A (MAOA), promoting inflammatory factors including nuclear factor kappa-B (NFκB), interleukin-6, and tumor necrosis factor α. The NFκB inhibitor sulfasalazine could alleviate the effects of TPhP on tryptophan metabolism disturbance. The MAOA inhibitor clorgyline or the antioxidant N-acetylcysteine can mitigate oxidative stress and eliminate TPhP-induced inflammatory factors and tryptophan metabolism disturbances. The data above suggest that TPhP disturbed tryptophan metabolism by activating NFκB through MAOA-mediated oxidative stress. Finally, using the mouse intrauterine exposure model, the results confirmed that TPhP induced oxidative stress, activated inflammatory factors, disturbed tryptophan metabolism, and increased the levels of the tryptophan metabolites serotonin, kynurenine, 3-hydroxykynurenine, and 3-hydroxyanthranilic acid in the placenta during the second trimester of pregnancy. Overall, TPhP can disturb placental tryptophan metabolism by activating the inflammatory factor NFκB, which was induced by MAOA-induced oxidative stress. The results of this study confirm that indirect exposure to xenobiotic compounds at an early life stage can impair offspring development and provide a novel perspective on the neurodevelopmental toxicity of TPhP.

Assessment of Daily Exposure to Organophosphate Esters through PM2.5 Inhalation, Dust Ingestion, and Dermal Contact

Inhalation of airborne fine particulate matter (PM2.5), dust ingestion, and dermal contact with dust are important pathways for human exposure to different contaminants, such as organophosphate esters (OPE), compounds that are widely used as flame retardants and plasticizers. There are limited studies assessing the extent of the contamination of OPE in indoor airborne PM2.5. This study offers a novel approach by examining various indoor environments, such as homes, workplaces, and means of transport, where people typically spend their daily lives. The goal is to provide a comprehensive assessment of daily exposure to these pollutants. Both PM2.5 and dust samples were collected in order to determine the concentration levels of 17 different OPEs. Fifteen OPEs in PM2.5 and 16 in dust samples were detected. Concentration levels in indoor air ranged from 4.37 to 185 ng/m3 (median 24.4 ng/m3) and from 3.02 to 36.9 μg/g for the dust samples (median 10.2 μg/g). Estimated daily intakes (EDIs) of OPEs were calculated for adults, yielding median values of 3.97 ng/(kg bw × day) for EDIInhalation, 5.89 ng/(kg bw × day) for EDIDermal, and 1.75 ng/(kg bw × day) for EDIIngestion. Such levels lie below human health threshold risk limits, although in some cases they could be only 2 times below the threshold for carcinogenic risk, with a main contribution from tris(2-chloroethyl) phosphate (TCEP). Given this threshold proximity, additional exposure to these chemicals from other pathways, such as food ingestion, gas phase exposure, and/or inhalation of coarser particles (PM10-2.5), could therefore lead to health limit exceedances.

Assessing human internal exposure to chemicals at different physical activity levels: A physiologically based kinetic (PBK) model incorporating metabolic equivalent of task (MET)

Physical activity levels have the potential to impact human internal exposure to environmental chemicals. However, the current lack of simple modeling approaches hinders the high-throughput screening of chemical exposure at different physical activity levels. To address this gap, this study proposes a straightforward model for assessing human internal exposure to chemicals. Our approach is based on the physiologically based kinetic (PBK) model and utilizes the metabolic equivalent of task (MET) to characterize internal exposure to chemicals at varying activity levels. To facilitate the application of this model, we have developed an Excel-based operation tool, allowing users to easily modify the MET value and generate simulation results for different physical activity levels. The simulation results demonstrate that as physical activity levels increase, the biotransfer factors (BTFs) of chemicals decrease, suggesting that higher physical activity levels reduce the bioaccumulation potential of chemicals. The intensified physical activity enhances the overall elimination kinetics of chemicals from the human body. However, the simulated concentrations of chemicals in the human body increase with higher physical activity levels, due to the significantly increased external exposure to chemicals, such as through inhalation. Our proposed modeling approach, along with the operational tool, enables high-throughput simulation of human chronic internal exposure to chemicals at different physical activity levels, where the findings can assist in screening chemicals for further health risk assessment. To accomplish this, the model incorporates certain assumptions and utilizes generic model input values. However, due to the intricate nature of the interaction between external and internal exposures at different physical activity levels, validating the simulation through experimental studies becomes challenging and is not performed in this study. For future studies, we recommend incorporating more MET-related physiological input variables, improving energy balance estimates, comprehending external exposure estimates, and conducting cohort studies to enhance and validate the proposed modeling approach.

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

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

Anti-androgenic activity of novel flame retardants in mixtures: Newly identified contribution from tris(2,3-dibromopropyl) isocyanurate (TDBP-TAZTO)

In recent decades, male infertility has been on the rise, largely attributed to exposure to chemicals with endocrine-disrupting properties. The adverse effects of disrupting androgen actions on the development and reproductive health of children and adolescents have been extensively studied. Flame retardants (FRs), used in consumer products to delay flammability, have been identified as antagonists of the androgen receptor (AR), potentially leading to adverse outcomes in male reproductive health later in life. This study examined the interaction of eight novel FRs with the AR, employing an in vitro AR-dependent luciferase reporter gene assay utilizing MDA-kb2 cells. The investigation revealed the anti-androgenic activity of tris(2,3-dibromopropyl) isocyanurate (TDBP-TAZTO), a frequently detected FR in the environment. Furthermore, TDBP-TAZTO contributed to anti-androgenic activity when combined with six other anti-androgenic FRs. The mixture effects were predicted by three commonly employed models: concentration addition (CA), generalized CA, and independent action, with the CA model showcasing the highest accuracy. This suggests that all FRs act through a similar mechanism, as further confirmed by in silico molecular docking, indicating limited synergy or antagonism. Importantly, in the mixtures, each FR contributed to the induction of anti-androgenic effects at concentrations below their individual effective concentrations in single exposures. This raises concern for public health, especially considering the co-detection of these FRs and their potential co-occurrence with other anti-androgenic chemicals like bisphenols. Therefore, our findings, along with previous research, strongly support the incorporation of combined effects of mixtures in risk assessment to efficiently safeguard population health.

Urinary phosphate is associated with cardiovascular disease incidence

INTRODUCTION

Elevated phosphate (P) in urine may reflect a high intake of inorganic P salts from food additives. Elevated P in plasma is linked to vascular dysfunction and calcification.

OBJECTIVE

To explore associations between P in urine as well as in plasma and questionnaire-estimated P intake, and incidence of cardiovascular disease (CVD).

METHODS

We used the Swedish Mammography Cohort-Clinical, a population-based cohort study. At baseline (2004-2009), P was measured in urine and plasma in 1625 women. Dietary P was estimated via a food-frequency questionnaire. Incident CVD was ascertained via register-linkage. Associations were assessed using Cox proportional hazards regression.

RESULTS

After a median follow-up of 9.4 years, 164 composite CVD cases occurred (63 myocardial infarctions [MIs] and 101 strokes). Median P (percentiles 5-95) in urine and plasma were 2.4 (1.40-3.79) mmol/mmol creatinine and 1.13 (0.92-1.36) mmol/L, respectively, whereas dietary P intake was 1510 (1148-1918) mg/day. No correlations were observed between urinary and plasma P (r = -0.07) or dietary P (r = 0.10). Urinary P was associated with composite CVD and MI. The hazard ratio of CVD comparing extreme tertiles was 1.57 (95% confidence interval 1.05, 2.35; P trend 0.037)-independently of sodium excretion, the estimated glomerular filtration rate, both P and calcium in plasma, and diuretic use. Association with CVD for plasma P was 1.41 (0.96, 2.07; P trend 0.077).

CONCLUSION

Higher level of urinary P, likely reflecting a high consumption of highly processed foods, was linked to CVD. Further investigation is needed to evaluate the potential cardiovascular toxicity associated with excessive intake of P beyond nutritional requirements.

Organophosphate esters in source, finished, and tap water in Wuhan, China

As important plasticizers and flame retardants, organophosphate esters (OPEs) have resulted in the contamination of various water bodies worldwide. However, their removal efficiency by different tap water treatment processes and seasonal variations in drinking water in China are not fully understood. In this study, source (n = 20), finished (n = 20), and tap (n = 165) water samples sourced from the Hanshui and the Yangtze River were collected in Wuhan, central China from July 2018 to April 2019 to measure selected OPE concentrations. The OPE concentrations in the source water samples ranged 10.5-113 ng/L (median: 64.6 ng/L). Most OPEs were not removed effectively by conventional tap water treatment, except for tris(2-chloroisopropyl) phosphate (TCIPP). Interestingly, trimethyl phosphate content was found to increase significantly during chlorination for water sourced from the Yangtze River. The OPEs could be removed more effectively by advanced processes with ozone and activated carbon (maximum removal efficiency of specific OPE was 91.0%). Similar cumulative OPE concentrations (ΣOPEs) values were found for the finished water and tap water in February rather than in July. The ΣOPEs (ng/L) in the tap water ranged 21.2-365 (median: 45.1). TCIPP and tris(2-chloroethyl) phosphate were the predominant OPEs in the studied water samples. Significant seasonal variations in the OPE residues in tap water were observed in this study. OPE exposure via tap water ingestion posed low health risks to human beings. This is the first study reporting the removal efficiencies of OPEs and the seasonal variations in tap water from central China. This is also the first study documenting the occurrence of cresyl diphenyl phosphate and 2,2-bis(chloromethyl)propane-1,3-diyltetrakis (2-chloroethyl) bisphosphate in tap water. Based on currently available data, the contamination of tap water by OPEs is in the order of Korea > eastern China > central China > New York State, the United States. Additionally, this study provides a method involving a trap column, to eliminate OPE contamination from the liquid chromatography system.

Independent and combined effects of exposure to organophosphate esters on thyroid hormones in children and adolescents

Toxicological studies suggest that organophosphate esters (OPEs) may impair thyroid function. Epidemiological evidence, related to children and adolescents, has not been reported, and little is known about the combined effects of exposure to OPE mixtures. In this study, we collected information of 1156 children and adolescents (aged 6-18 years, 48.4% males) from a cross-sectional study in Liuzhou, China, and measured the levels of 15 urinary OPE metabolites and 5 serum thyroid hormones. Multivariate linear regression and quantile g-computation (QGC) approach were used to examine the associations which adjusted for demographic and lifestyle characteristics. Few participants had levels of triiodothyronine (T3) and free thyroxine (FT4) outside age-specific pediatric ranges. QGC analyses showed that individuals in the second, third, and fourth quartiles (Q2-Q4) of exposure had 3.93% (2.14%, 5.75%), 8.01% (4.32%, 11.8%), and 12.3% (6.54%, 18.3%) higher T3 than those in the first quartile (Q1), with similar pattern for free triiodothyronine (FT3). Individuals in Q2 and Q3 had higher thyroid-stimulating hormone (TSH) than those in Q1, but no differences were observed in TSH between Q1-Q4. In contrast, compared to the lowest quartile, FT4 was lower for those in Q2 (- 1.54%; 95% CI: - 3.02%, -0.04%), Q3 (-3.07%; 95% CI: -5.95%, -0.09%), and Q4 (-4.56%; 95% CI: - 8.80%, - 0.13%). These associations were consistent with the results from multivariate linear regression. When stratified by sex, OPE exposure (individual or mixtures) was associated with increased T3 and FT3 in males and decreased FT4 in females. This study provides the first evidence to characterize the thyroid-disrupting effects of OPE exposure in children and adolescents.

A modified QuEChERS method for determination of organophosphate esters in milk by GC-MS

Organophosphate esters (OPEs) are substances that have been detected in several matrices due to their use as flame retardants and plasticizers. Human exposure to OPEs can cause endocrine disruption, hormonal problems, and reproductive disturbance. Ingestion of contaminated food can be a significant route of exposure to OPEs. Food can be contaminated by OPEs in the food chain, during cultivation, and by contact with plasticizers during the production chain of processed foods. In this study, a method for the determination of 10 OPEs in commercial bovine milk was developed. The procedure was based on QuEChERS extraction and gas chromatography coupled to mass spectrometry (GC-MS) analysis. QuEChERS modification included a freezing-out step after the extraction followed by the concentration of the entire acetonitrile phase before the clean-up step. Calibration linearity, matrix effects, recovery, and precision were evaluated. Significant matrix effects were observed, which could be compensated by the isotopically labeled internal standard quantification and matrix-matched calibration curves. Recoveries ranged from 77 to 105%, with a relative standard deviation ranging from 3 to 38%. The method detection limits (MDLs) were in the range of 0.031-6.7 ng mL^-1, while the method quantification limits (MQLs) were within the range from 0.27 to 20 ng mL^-1. The proposed method was successfully validated and applied to determine the concentrations of OPEs in bovine milk. The 2-ethylhexyl diphenyl phosphate (EHDPHP) was detected in the analyzed milk samples but at levels below the MQL.

Occurrences and migration of organophosphite and organophosphate esters into food simulants from single-use food packaging in China

Organophosphite antioxidants (OPAs) and organophosphate esters (OPEs) are used as additives in food packaging. Because these chemicals have been found in various foods, they have caused increasing concern about potential health risks through food intake. Little information is available about the migration behaviors of OPAs and OPEs from single-use food packaging into food. In the present study, four OPAs and 23 OPEs were analyzed in paper and plastic single-use food packaging (n = 312), which are widely used for take-out food in China. The total concentrations of OPAs and OPEs in the packaging samples were 1966 and 189 ng/g, respectively. Tris (2,4-di-tert-butylphenyl) phosphite (AO168) was the dominant compound. OPAs and OPEs were present at higher concentrations in the plastic packaging than in the paper packaging. In a migration test, four OPAs and 15 OPEs were found in food simulants (4% acetic acid, 10% ethanol, and hexane). Higher levels of individual and total OPAs were found in hexane than the other food simulants, especially for AO168 migration from plastic packaging. The amounts of OPEs in the food simulants increased from the aqueous simulants (4% acetic acid and 10% ethanol) to the fatty food simulant (hexane). The migration efficiencies of the OPAs were higher than those of the OPEs. Preliminary calculations suggest that dietary exposure to OPAs and OPEs because of migration will be low for the population in China.

Discovery of Three Organothiophosphate Esters in River Water Using High-Resolution Mass Spectrometry

Records of the environmental occurrence of organothiophosphate esters (OTPEs), which are used as flame retardants and food and industrial additives, are unavailable. In this study, we discovered three OTPEs, namely O,O,O-tris(2,4-di-tert-butylphenyl) phosphorothioate (AO168═S), O-butyl O-(butyl-methylphenyl) O-(di-butylphenyl) phosphorothioate (BBMDBPt)/O,O-bis(dibutylphenyl) O-methyl phosphorothioate (BDBPMPt), and O-butyl O-ethyl O-hydrogen phosphorothioate (BEHPt), in the surface water of the Yangtze River Basin by applying a characteristic phosphorothioate fragment-directed high-resolution mass spectrometry method. Among the 17 water samples tested, the detection frequencies of AO168═S and BEHPt were 100% and that of BBMDBPt/BDBPMPt was 29%. The mean concentration of AO168═S was 56.9 ng/L (30.5-148 ng/L), and semi-quantitative analysis revealed that the mean concentrations of BEHPt and BBMDBPt/BDBPMPt were 17.2 ng/L (5.5-65.4 ng/L) and 0.8 ng/L (<the limit of quantification, LOQ, to 6.3 ng/L), respectively. Twelve organophosphate esters were also detected, of which the highest mean concentration was found for tris(2,4-di-tert-butylphenyl) phosphate (AO168═O, 366 ng/L), followed by triphenyl phosphate (84.3 ng/L), triethyl phosphate (19.3 ng/L), and tributyl phosphate (15.7 ng/L). The Spearman's correlation coefficient between AO168═S and AO168═O was 0.547 (p < 0.05), suggesting that AO168═S commonly transforms into AO168═O or that these chemicals have a similar source and behavior in the environment. Future studies are warranted to assess the potential toxicity, environmental behavior, and health risks posed by OTPEs.

Human exposure to organophosphate esters in water and packed beverages

Drinks are an essential part of human diet, which makes them a source of human exposure to plasticizers such as organophosphate esters (OPEs). The current study provides new information about sixteen OPE levels in 75 different samples (tap water, packed water, cola drinks, juice, wine and hot drinks). Tap water mean levels (40.9 ng/L) were statistically higher than packed water mean levels (4.82 ng/L), mainly due to the contribution of tris(2-chloroisopropyl) phosphate (TCIPP) and tris(2-butoxyethyl) phosphate (TBOEP) that may come from PVC water pipes. Over 90% of samples presented at least one OPE, where regular cola drinks had the highest mean concentrations (2876 ng/L). There was a significantly higher presence of OPEs in added sugar beverages than sugar free drinks, especially for 2-ethylhexyl diphenyl phosphate (EHDPP), which might be related not only to packaging materials but to the added sugar content. Estimated daily intakes (EDIs) in normal and high-exposure scenarios were 2.52 ng/kg bw/day and 7.43 ng/kg bw/day, respectively. Human risk associated with beverages ingestion showed regular cola drinks, juice and tap water as the groups with the highest hazard quotients (HQs). Although OPE exposure was below to safety limits, it should be noted that EHDPP values for regular cola group must be cause of concern, and other routes of exposure such as food ingestion or air inhalation should be also considered.

Descriptive analysis of organophosphate ester metabolites in a pan-Canadian pregnancy cohort

Organophosphate esters (OPEs) are widely used in numerous consumer products for their flame retardant and plasticizing properties. Despite potential widespread exposure, biomonitoring data during critical windows of development are scarce and limited to the most widely studied metabolites. We quantified urinary concentrations of multiple OPE metabolites in a vulnerable Canadian population. Using data and biobanked specimens from the Maternal-Infant Research on Environmental Chemicals (MIREC) study (2008-2011), we measured first trimester urinary concentrations of 15 OPE metabolites as well as one flame retardant metabolite and quantified associations with sociodemographic and sample collection characteristics in 1865 pregnant participants. We applied 2 different analytical methods to quantify OPEs, one using UItra-Performance Liquid Chromatography coupled to tandem mass spectrometry (UPLC-MS/MS) and the other using Atmospheric Pressure Gas Chromatography coupled to mass spectrometry (APGC-MS/MS) with sensitive limits of detection (0.008-0.1 μg/L). We modelled associations between sociodemographic and sample collection characteristics and specific gravity-standardized chemical concentrations. Six OPE metabolites were detected in the majority (68.1-97.4 %) of participants. Bis-(2-chloroethyl) hydrogen phosphate had the highest detection rate (97.4 %). Diphenyl phosphate had the highest geometric mean concentration (0.657 μg/L). Metabolites of tricresyl phosphate were detected in few participants. Associations between sociodemographic characteristics varied according to each OPE metabolite. Pre-pregnancy body mass index tended to be positively associated with OPE metabolite concentrations whereas age tended to be inversely associated with OPE concentrations. OPE concentrations were, on average, higher in urine samples collected in the summer than other seasons the winter. We present the largest biomonitoring study of OPE metabolites in pregnant people to date. These findings demonstrate widespread exposure to OPEs and their metabolites and identify subpopulations who may experience heightened exposure.

Associations of urinary organophosphate esters metabolites and diet quality with nonalcoholic/metabolic dysfunction-associated fatty liver diseases in adults

Whether exposure to organophosphate esters (OPEs) is associated with metabolic dysfunction-associated fatty liver disease (MAFLD) and nonalcoholic fatty liver disease (NAFLD) remains unclear. A healthy diet is crucial to metabolic health and dietary intake is also an important route for OPEs exposure. However, the joint associations of OPEs, diet quality, and the effect modification by diet quality remain unknown. This study comprised 2618 adults with complete data on 6 urinary OPEs metabolites, 24 h dietary recalls, and definitions of NAFLD and MAFLD from the 2011-2018 National Health and Nutrition Examination Survey cycles. Multivariable binary logistic regression was applied to assess the associations of OPEs metabolites with NAFLD, MAFLD, and components of MAFLD. We also adopted the quantile g-Computation method to examine the associations of OPEs metabolites mixture. Our results revealed that OPEs metabolites mixture and three individual metabolites [i.e., bis(1,3-dichloro-2-propyl) phosphate (BDCIPP), bis(2-chloroethyl) phosphate, and diphenyl phosphate] were significantly and positively associated with NAFLD and MAFLD (P-trend<0.001), with BDCIPP being identified as the dominant metabolite, whereas the 4 diet quality scores were monotonically and inversely associated with both MAFLD and NAFLD (P-trend<0.001). Of note, 4 diet quality scores were by and large negatively associated with BDCIPP, but not with other OPEs metabolites. Joint association analyses revealed that individuals with higher diet quality and lower BDCIPP concentration tend to have lower odds of having MAFLD and NAFLD in comparison with people in the low diet quality and high BDCIPP group, but the associations of BDCIPP were not modified by diet quality. Our findings suggest that certain OPEs metabolites and diet quality exhibited opposing associations with both MAFLD and NAFLD. Individuals adherent to a healthier diet may have a lower level of certain OPEs metabolites, and thus could have lower odds of having NAFLD and MAFLD.

Organophosphate esters in Chinese rice: Occurrence, distribution, and human exposure risks

Dietary intake is a crucial pathway of organophosphate esters (OPEs) exposure for human. However, information about the exposure risk of OPEs via rice consumption is still largely unknown. In the present study, a total of 234 rice samples from 25 provinces or city of China were collected and the concentrations of 24 OPEs were determined. Sixteen OPEs were detected in these rice samples and each rice sample was contaminated with at least 5 OPEs, indicating a ubiquitous occurrence of OPEs in Chinese rice. Moreover, the concentrations of Σ16 OPEs ranged from 1.46 to 552.65 μg/kg dry weight (dw), with a mean value of 64.74 μg/kg dw. For the composition profile of OPEs, three Cl-OPEs, including tris(2-chloroethyl) phosphate (TCEP), tri(2-chloroisopropyl) phosphate (TCIPP) and tris(1,3-dichloro-2-propyl) phosphate (TDCIPP), accounted for the highest proportion of Σ16 OPEs. For the spatial distribution of OPEs, although obvious spatial variations were observed among the 25 provinces or city, no obvious variations were found among the six rice-cultivating regions of China. Additionally, estimated dietary intakes (EDI) values of the 16 OPEs for adults and children were 1105.24 and 1399.13 ng/kg bw/day, respectively, under the high intake scenario. The hazard indexes of the 10 OPEs were 0.108 and 0.137 for adults and children, respectively. The risk assessment results indicated that Chinese adults and children did not suffer significant adverse effects from OPEs via rice intake.

Emissions and fate of organophosphate esters in outdoor urban environments

Cities are drivers of the global economy, containing products and industries that emit many chemicals. Here, we use the Multimedia Urban Model (MUM) to estimate atmospheric emissions and fate of organophosphate esters (OPEs) from 19 global mega or major cities, finding that they collectively emitted ~81,000 kg yr^-1 of ∑₁₀OPEs in 2018. Typically, polar "mobile" compounds tend to partition to and be advected by water, while non-polar "bioaccumulative" chemicals do not. Depending on the built environment and climate of the city considered, the same compound behaves like either a mobile or a bioaccumulative chemical. Cities with large impervious surface areas, such as Kolkata, mobilize even bioaccumulative contaminants to aquatic ecosystems. By contrast, cities with large areas of vegetation fix and transform contaminants, reducing loadings to aquatic ecosystems. Our results therefore suggest that urban design choices could support policies aimed at reducing chemical releases to the broader environment without increasing exposure for urban residents.

Armour G, Horman BM, Rock KD, Witchey SK, Greenbaum A, Patisaul HB. Maternal organophosphate flame retardant exposure alters the developing mesencephalic dopamine system in fetal rat

Organophosphate flame retardants (OPFRs) have become the predominant substitution for legacy brominated flame retardants but there is concern about their potential developmental neurotoxicity (DNT). OPFRs readily dissociate from the fireproofed substrate to the environment, and they (or their metabolites) have been detected in diverse matrices including air, water, soil, and biota, including human urine and breastmilk. Given this ubiquitous contamination, it becomes increasingly important to understand the potential effects of OPFRs on the developing nervous system. We have previously shown that maternal exposure to OPFRs results in neuroendocrine disruption, alterations to developmental metabolism of serotonin (5-HT) and axonal extension in male fetal rats, and potentiates adult anxiety-like behaviors. The development of the serotonin and dopamine systems occur in parallel and interact, therefore, we first sought to enhance our prior 5-HT work by first examining the ascending 5-HT system on embryonic day 14 using whole mount clearing of fetal heads and 3-dimensional (3D) brain imaging. We also investigated the effects of maternal OPFR exposure on the development of the mesocortical dopamine system in the same animals through 2-dimensional and 3D analysis following immunohistochemistry for tyrosine hydroxylase (TH). Maternal OPFR exposure induced morphological changes to the putative ventral tegmental area and substantia nigra in both sexes and reduced the overall volume of this structure in males, whereas 5-HT nuclei were unchanged. Additionally, dopaminergic axogenesis was disrupted in OPFR exposed animals, as the dorsoventral spread of ventral telencephalic TH afferents were greater at embryonic day 14, while sparing 5-HT fibers. These results indicate maternal exposure to OPFRs alters the development trajectory of the embryonic dopaminergic system and adds to growing evidence of OPFR DNT.

Organophosphate esters (OPEs) in a coral reef food web of the Xisha Islands, South China Sea: Occurrence, trophodynamic, and exposure risk

Despite organophosphate esters (OPEs) are widely prevalent in the environment, however, limited information is available regarding their occurrence, trophodynamics, and exposure risks in coral reef ecosystems. In this study, 11 OPEs were investigated in a tropical marine food web (7 fish species and 9 benthos species) from the Xisha (XS) Islands, South China Sea (SCS). The ∑₁₁OPEs were 1.52 ± 0.33 ng/L, 2227 ± 2062 ng/g lipid weight (lw), 1024 ± 606 ng/g lw, and 1800 ± 1344 ng/g lw in seawater, fish, molluscs, and corals, respectively. Tris (2-chloroisopropyl) phosphate (TCIPPs) were the dominant OPEs in seawater, fish, and molluscs, while tris (2-butoxyethyl) phosphate (TBOEP) predominated in coral tissues. Abiotic and biotic factors jointly affect the OPEs enrichment in marine organisms. Trophic magnification factors (TMFs) (range: 1.31-39.2) indicated the biomagnification potency of OPEs. A dietary exposure risk assessment indicated that OPEs at current levels in coral reef fish posed a low risk to human health but were not negligible. Overall, this study contributes to a further understanding of the environmental behaviors of OPEs in coral reef ecosystems.

Gestation and lactation triphenyl phosphate exposure disturbs offspring gut microbiota in a sex-dependent pathway

Triphenyl phosphate (TPhP) is an Organophosphate flame retardant (OPFR) that has been widely used in many commercial products. Following its widely usage, its health risk has been concerned. In this study, mice were exposed to TPhP (1 mg/kg) during pregnancy and lactation (E0-PND21), the effect of TPhP on gut microbiota and its role in TPhP mediated lipid metabolism disturbance of offspring was investigated. Our results showed that TPhP disturbed the gut microbiota in dam or offspring at different extent, with male offspring experiencing major effects. Both the composition, abundance or network of gut microbiome was affected in male offspring. In male offspring, expression of genes along gut-liver axis including FXR, CYP7A1, SREBP-1c and ChREBP was significantly up-regulated, and expression of SHP, FGF15 and ASBT was significantly down-regulated. Consistent with this, lipid accumulation in the liver, and increased level of triglyceride, total cholestrol and total bile acid in the serum was observed. The changed abundance of Ruminococcaceae, Clostridiaceae, and Bacteroidaceae shows strong correlation with disturbed lipid metabolism in male offspring. Our research showed that indirect TPhP exposure during early life stage could affect the gut microbiota and gene expression along gut-liver axis in offspring at sex-dependent pathways, with males experiencing more effects.

Integrating Physiologically Based Pharmacokinetic Modeling-Based Forward Dosimetry and in Vitro Bioassays to Improve the Risk Assessment of Organophosphate Esters on Human Health

The ability to accurately assess the health risks of contaminants is limited by the shortcomings of toxicological standards. Using organophosphate esters (OPEs) as an example, this study attempted to integrate physiologically based pharmacokinetic (PBPK)-based forward dosimetry and in vitro bioassays to assess the likelihood of contaminants inducing biological effects in humans. The total exposure level of OPEs for Chinese residents was 19.5 ± 8.71 ng/kg/day with inhalation being the main exposure pathway. Then, human PBPK models were developed for individual OPEs to predict their steady-state concentrations in human tissues, and the predicted median levels in blood were close to the measurements. The reference doses (RfDs) of OPEs based on in vitro bioassays were comparable to in vivo animal-derived RfDs, demonstrating the reliability of in vitro bioassays. Therefore, the likelihood of OPEs inducing bioactivities in humans (RQ_in-vitro) was calculated using in vitro toxicity data and OPE levels in human tissues. The RQ_in-vitros of tris(2-chloroisopropyl) phosphate, tris(1,3-dichloropropyl) phosphate, and triphenyl phosphate (7.68 × 10^-5-3.18 × 10^-3) were comparable to the risks assessed using traditional RfDs (5.22 × 10^-5-1.94 × 10^-3), indicating the credibility of the method proposed in this study. This study establishes a new framework to improve the health risk assessment of contaminants without sufficient toxicity data and minimize the need for animal experimentation.

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

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

Dietary intake assessment of known and unknown organophosphate esters (OPEs) in foodstuffs via high-resolution mass spectrometry

We applied an integrated target, suspect, and non-target screening strategy to analyze known and unknown organophosphate esters (OPEs) in 107 foodstuffs collected from Nanjing City, China, in 2020. Twelve out of 19 target OPEs were detectable in at least one of the analyzed samples. Among the nine food categories, meat samples were contaminated the most severely with a mean ΣOPEs concentration of 68.5 ng/g wet weight (ww). In most food categories, tris(2,4-di-tert-butylphenyl) phosphate was the predominant OPE with a mean concentrations of 2.26 ng/g ww. In the food extract samples, suspect and non-target analysis identified other 6 suspect OPEs and 1 non-target OPE, of which two were fully identified as tri-m-cresyl phosphate, and trihexyl phosphate. Based on the measured OPE concentrations, we estimated the daily per capita dietary intakes of ΣOPEs for Nanjing residents to be 423 ng/kg bw/day, which is less than the reference dosage value of each OPE. Collectively, this study provides new information regarding the comprehensive identification of OPEs in foodstuffs, and revealed the importance of dietary risk assessment of this emerging class of contaminants.

Aryl-, halogenated- and alkyl- organophosphate esters induced oxidative stress, endoplasmic reticulum stress and NLRP3 inflammasome activation in HepG2 cells

Organophosphate esters (OPEs) are a group of extensively used man-made chemicals with diverse substituents that are ubiquitously detected in human-related samples including serum, breastmilk, food and house dust. The understanding of their toxicological effects and potential mechanisms on hepatocytes is still limited. In this study, nine most frequently detected OPEs were selected and divided into three subgroups (aryl-, halogenated- and alkyl-OPEs) based on their substituents. The cytotoxicity, apoptosis, oxidative stress, endoplasmic reticulum (ER) stress and NLRP3 inflammasome activation induced by OPEs were evaluated in human hepatocellular carcinomas HepG2 cells. All OPEs induced apoptosis likely through a caspase-dependent apoptotic pathway. The activities of anti-oxidative enzyme SOD and CAT exhibited sensitive responses after OPEs treatment for 6 h. The OPEs induced ROS overproduction, DNA damage, endoplasmic reticulum (ER) stress and NLRP3 inflammasome activation varied among aryl-, halogenated- and alkyl-OPEs. Halogenated- and alkyl- OPEs induced overproduction of ROS and DNA damage, and elevated ER stress and NLRP3 inflammasome activation are observed aryl-OPEs induced cytotoxicity.

Occurrence, spatial variation, seasonal difference, and ecological risk assessment of organophosphate esters in the Yangtze River, China: From the upper to lower reaches

A comprehensive contamination profile of organophosphate esters (OPEs) in the Yangtze River in China has not yet been characterized. In this study, we investigated the occurrence, spatial variation, and seasonal difference of 18 selected OPEs in surface water samples of the Yangtze River mainstream. To characterize the contamination profile of the OPEs, we collected 144 Yangtze River water samples from 72 sampling sites in December 2020 and June 2021. Four alkyl-OPEs [trimethyl phosphate, triethyl phosphate (TEP), tributyl phosphate, and tris(2-butoxyethyl) phosphate (TBOEP)] and three halogenated OPEs [tris(2-chloroethyl) phosphate (TCEP), tris(1-chloro-2-propyl) phosphate (TCIPP), and tris(1,3-dichloro-2-propyl) phosphate] were the most frequently detected target compounds (>95%). TCIPP (median: 34.6 ng/L), TEP (median: 26.2 ng/L), and TCEP (median: 17.9 ng/L) were the most abundant compounds, while the median values of the others were below 10 ng/L. Additionally, the concentrations of most OPEs gradually/dramatically increased from upstream to downstream Yangtze River. Notably, the median concentration of summed OPEs in Shanghai (415 ng/L; downstream) was approximately ten times higher than that in Qinghai (45.7 ng/L; upstream). Urban sampling sites had significantly or slightly higher concentrations of most OPEs than rural sampling sites. Moreover, the OPE concentrations in the river water differed between the winter and summer. The concentrations of summed OPEs (median: 117 vs. 106 ng/L), summed alkyl-OPEs (67.0 vs. 45.8 ng/L; p < 0.05), and summed aryl-OPEs (0.48 vs. 0.17 ng/L; p < 0.05) were slightly or significantly higher in December than those in June; nevertheless, summed halogenated OPEs were slightly higher in June (62.2 vs. 50.2 ng/L) than that in December. Compared with previously reported data for OPEs in other major rivers worldwide, the Yangtze River water had relatively lower concentrations of the OPEs than those in the rivers of developed countries and regions. Ecological risk assessment suggested that tris(2-ethylhexyl) phosphate and TCEP posed relatively high risks (RQ: 1.01 and 0.98, respectively) at the maximum concentration, and TBOEP posed a moderate risk (RQ: 0.25). This is the first study to comprehensively characterize the contamination profile of the Yangtze River by the OPEs.

Associations between organophosphate esters concentrations and markers of liver function in US adolescents aged 12-19 years: A mixture analysis

Liver disease has become a growing health burden, and little is known about the impairment of liver function caused by exposure to organophosphate esters (OPEs) in adolescents aged 12-19 years in the United States. To investigate the relationship between urinary metabolites of OPEs including diphenyl phosphate (DPHP), bis(1,3-dichloro-2-propyl) phosphate (BDCPP), bis(1-chloroethyl) phosphate (BCPP), bis(2-chloroethyl) phosphate (BCEP), and dibutyl phosphate (DBUP) and liver function in US adolescents aged 12-19 years. Liver function tests (LFTs) include aspartate aminotransferase (AST), albumin (ALB), alanine aminotransferase (ALT), alkaline phosphatase (ALP), gamma-glutamyl transferase (GGT), total bilirubin (TBIL), total protein (TP), and AST/ALT. Meanwhile, potential confounding and interaction effects were assessed. The study sample included 592 adolescents aged 12-19 from two consecutive NHANES cycles (2011-2012, 2013-2014). A composite statistical strategy combining traditional linear regression with advanced multi-pollutant models quantile based g-computation (QGC) and eXtreme Gradient Boosting (XGBoost) regression was used to analyze the joint effects of multiple OPEs on liver function indicators, and to describe the interaction between different OPEs in detail. 592 adolescent participants were 15 (14-17) years old, with similar numbers of males and females (304 vs. 288). The analysis results showed that (1) in the linear regression model, individual DPHP, BCEP exposure and ALP changes, BCEP and AST/ALT changes were positively associated. DPHP, BDCPP were negatively associated with TP changes. (2) The combined effects of various OPEs on ALB, ALT, ALP, GGT, TBIL, TP, and AST/ALT were statistically significant. (3) There is no potential interaction between different OPEs. Several OPEs and their combinations are closely related to the 8 LFT indicators. In addition, data suggest that exposure to OPEs in adolescents may be associated with liver damage. Due to limited evidence in the literature and potential limitations of the current study, our findings require more studies to confirm.

Exposure to organophosphorus compounds of Japanese children and the indoor air quality in their residences

Several organophosphorus compounds such as organophosphate pesticides (OPPs) and trialkylphosphates (TAPs) are suspected to inhibit cholinesterase activities, to affect endocrine systems or to possibly be carcinogenic. To evaluate their adverse effects on health with chronic exposure in the general population, especially in children, we measured the household exposure to OPPs and TAPs by Japanese children via all exposure pathways and the contribution of indoor air quality. First-morning void urine was collected from subjects aged 6 to 15 years (n = 132), and airborne organophosphorus compounds were sampled in the subject's bedroom for 24 h. Airborne levels of nine OPPs and three TAPs and their urinary metabolites were determined. No significant correlations were detected for any compounds between their airborne concentrations and the urinary excretion amounts of their corresponding metabolites. The estimated daily intakes were as follows (median, μg/kg b.w./d): chlorpyrifos, 0.042; diazinon, 0.067; tri-n-butylphosphate, 0.094. The 95th percentiles of the intakes for fenthion, fenitrothion and the above three compounds did not exceed their reference limit values, although one subject had a daily intake of tri-n-butylphosphate that was about twice its reference limit value. The concentration levels of the urinary metabolite of tri-n-butylphosphate in our subjects tended to be higher than those for children in many other countries. The fractions of the amounts absorbed by inhalation to the amounts absorbed via all of the exposure pathways was only 2.3 % (median) for tri-n-butylphosphate. Inhalation did not seem to contribute very much as an absorption pathway of the organophosphorus compounds in these Japanese children while they were at home. The exposure amounts of OPPs were not suggested to be high enough to adversely affect the health of these children at present on the basis of their daily intakes compared to their reference limit values.

Organophosphate esters in UK diet; exposure and risk assessment

Food ingestion has been established as an important human exposure route to many environmental contaminants (brominated flame retardants, dioxins, organochlorine pesticides etc). However, information regarding dietary exposure to organophosphate esters (OPEs) in the UK remains limited. This study provides the first comprehensive dataset on OPEs in the UK diet by measuring concentrations of eight OPEs in 393 food samples, divided into 15 food groups, collected from Birmingham, UK. All target OPEs were measured above the limit of quantification in at least one of the food groups analysed. Concentrations were highest (mean ∑₈OPEs = 18.4 ng/g wet weight (ww)) in milk and milk products, followed by those in cereal and cereal products (mean ∑₈OPEs = 15.9 ng/g ww), with concentrations lowest in chickens' eggs (mean ∑₈OPEs = 1.61 ng/g ww). Interestingly, concentrations in animal-derived foods (mean ∑₈OPEs = 44.2 ng/g ww) were statistically indistinguishable (p˃0.05) from plant-derived foods (mean ∑₈OPEs = 36.8 ng/g ww). Estimated daily dietary intakes (EDIs) of ∑₈OPEs under mean and high-end exposure scenarios for the four age groups considered were: toddlers (420 and 1547 ng/kg bw/day) ˃ children (155 and 836) ˃ elderly (74.3 and 377) ˃ adults (62.3 and 278) ng/kg bw/day, respectively. Baby food contributed 39 % of ∑₈OPEs exposure for toddlers, with non-alcoholic beverages contributing 27 % of exposure for children, while cereal and cereal products (25 %) and fruits (22 %) were the main contributors for adults and the elderly. The concentrations of OPEs in UK foodstuffs were generally of the same order of magnitude as those reported for other countries and our estimates of dietary exposure were well below the corresponding health-based limit values.