Organophosphite Antioxidants in Indoor Dust Represent an Indirect Source of Organophosphate Esters

Adverse Effects of Aryl Organophosphate Esters on Reproduction

Aryl organophosphate esters (AOPEs) have been widely detected in environmental media and human samples, and increasing evidence shows that AOPEs induce adverse effects on reproductive health. This Review summarizes the exposure levels, reproductive toxicity data, and underlying mechanisms of three legacy AOPEs, including triphenyl phosphate (TPHP), 2-ethylhexyl diphenyl phosphate (EHDPP), and tricresyl phosphate (TCrP). Reproduction-related nuclear receptors (RrNRs) were concluded to play important roles in the reproductive toxicity induced by AOPEs, as all three typical AOPEs and their hydroxylated metabolites elicit binding affinity to RrNRs. We further investigated the RrNRs binding ability of the other 55 emerging AOPEs (eAOPEs) through molecular docking and found most eAOPEs (54/55) showed potential binding ability to RrNRs, especially to estrogen receptor α. This Review helped us to comprehensively understand the adverse effects of AOPEs on reproduction and predict the potential health risk of eAOPEs. AOPEs are easily metabolized in organisms, and their hydroxylated metabolites even show more potency to bind RrRNs. This Review also highlights the necessity to take the contribution of hydroxylated metabolites into account in future research.

Aqueous secondary formation substantially contributes to hydrophilic organophosphate esters in aerosols

Chemicals of emerging concern (CECs), like organophosphate esters (OPEs), are toxic substances threatening human and wildlife health. Yet the atmospheric transformation of CECs remains poorly understood. Here we combine field measurements and partitioning models to reveal that OPEs could be enhanced by aqueous-phase processes in aerosols. We show that hydrophobic OPEs are absorbed favorably into the organic phase, whereas hydrophilic OPEs preferably partition into the aqueous phase. We provide field evidence that enhanced aqueous secondary formation of OPEs occurs in winter, and its magnitude is strongly dependent on aerosol water content. We suggest that dissolved inorganic salts and transition metals in aerosols positively impact the formation of particle-bound hydrophilic OPEs, by facilitating aqueous partitioning and/or oxidation. Our findings highlight the important role of aqueous oxidation chemistry for the fate of CECs in the atmosphere, urging better consideration of transformation products in future risk assessment and chemical management.

Traditional and novel organophosphate esters in atmosphere of greenhouse covered with mulch films: Seasonal variations, partitioning and exposure risks

Mulch films play a critical role in the accumulation of organophosphate esters (OPEs) in greenhouse soils. However, their impact on the occurrence, partitioning and health risks of atmospheric OPEs is unclear. This study fully investigated multi-media distributions of eleven traditional OPEs and four novel OPEs in greenhouses covered with degradable mulch films. The atmospheric concentrations exhibited substantial variability, ranging from 539 to 14821 pg/m³ in the gas phase and from 242 to 8320 pg/m³ in the particle phase, with summer levels higher than winter levels. Significant correlations (p < 0.05) were detected between OPE concentrations in mulch films and in air, indicating mulch films as a major source. First-order kinetic model effectively characterized the release patterns of dominant congeners including triphenyl phosphate and tris(2,4-ditert-butylphenyl) phosphate from degradable films. The Li-Ma-Yang model showed superior predictive capability for gas-particle partitioning than the Harner-Bidleman model. Total concentrations of OPEs in uncoated soils were at a range of 274-955 μg/kg. Soil-air exchange behaviors of OPEs governed by inherent volatility exhibited a seasonal dependence. While non-carcinogenic risks of OPEs for greenhouse farmers via air inhalation and dermal contact were negligible, holistic health assessments should integrate other uptake pathways and consider transformation products of OPEs.

Detection and screening of organophosphate esters in infant formula from Shanghai, China: distribution characteristics and risk evaluation

Organophosphate esters (OPEs) have raised great concerns in recent years. However, information regarding their occurrence in infant formula remains limited. Thus, thirty-two OPEs were measured in infant formula sold in Shanghai, China in 2023. The results showed that OPE occurrence in infant formula was widespread. The median concentrations of organophosphate diesters, organophosphate triesters, and total OPEs were 2.28, 5.20, and 8.63 ng/g, respectively. Tris(2-chloroisopropyl) phosphate (TCPP) showed the highest median concentration (1.95 ng/g), followed by triethyl phosphate, bis(1-chloro-2-propyl) phosphate (BCPP), tri-isobutyl phosphate, and triphenyl phosphate (0.532-0.581 ng/g). The dominant chloro-OPEs (TCPP and BCPP) were regional-specific. Compared to corresponding triesters, the diester concentrations were often lower, except for bis(2-butoxyethyl) phosphate and tributoxyethyl phosphate. Additionally, five novel OPEs with phenyl groups were identified, showing high detection frequencies and comparable concentrations to TCPP. Raw materials and food processing methods might affect individual OPEs. The estimated daily intakes (EDIs) ranged from 62.3 to 355 ng/kg bw/day. The highest EDI occurred in infants of 0-6 months of age but posed no obvious health risk for infants and toddlers. Further studies are still needed to evaluate the possible health implications arising from the novel OPEs and their metabolites, as well as the potentially synergistic effects.

Strategies to Reduce Uncertainties from the Best Available Physicochemical Parameters Used for Modeling Novel Organophosphate Esters across Multimedia Environments

Organophosphate esters (OPEs) raise growing environmental and human health concerns globally. However, numerous novel OPEs lack data on physicochemical properties, which are essential for assessing environmental fate, exposure, and risks. This study predicted water solubility (Sw), vapor pressure (Vp), octanol-water partition coefficient (Kow), and octanol-air partition coefficient (Koa) at 25 °C for 46 novel OPEs by identifying optimal in silico tools and establishing prediction strategies based on molecular weights (MWs). Prediction discrepancies between in silico tools increased with MWs and structural complexity. Method evaluations for compounds with MWs > 450 g/mol suggest that COSMOtherm is advantageous in predicting Sw and Vp for alkyl-OPEs, while SPARC is better for predicting Vp for aryl- and halogenated-OPEs. For compounds with MWs > 500 g/mol, COSMOtherm and SPARC are recommended for Kow and Koa prediction, respectively. For smaller OPEs, average values from the top three of COSMOtherm, SPARC, EPI Suite, and OPERA, ranked by validation on traditional flame retardants, are recommended. Using improper software could cause deviations in multimedia distribution and overall persistence in the environment by up to 83 and 350%, respectively. The present data and prediction strategy are useful to enhance the reliability of environmental fate, exposure, and risk assessments of various OPEs and emerging contaminants.

Maternal Exposure to Environmentally Relevant Concentrations of Tris(2,4-di-tert-butylphenyl) Phosphate-Induced Developmental Toxicity in Zebrafish Offspring via Disrupting foxO1/ripor2 Signaling

Abnormal development and mortality in early life stages pose significant threats to the growth and continuation of fish populations. Tris(2,4-di-tert-butylphenyl) phosphate (TDtBPP) is a novel organophosphate ester contaminant detected in natural waters. However, the potential effects of maternal exposure to TDtBPP on the early development of offspring embryos in fish remain unknown. Here, 30-day-old zebrafish were exposed to TDtBPP at 0, 50, 500, or 5000 ng/L for 180 days, and the exposed females were spawned with unexposed males. TDtBPP accumulation was detected in offspring embryos, accompanied by an increased malformation rate and mortality. The developmental abnormality of offspring embryos was identified to originate from the gastrula stage. Furthermore, based on transcriptome analysis, the down-regulation of RHO family interacting cell polarization regulator 2 gene (ripor2) was considered as a key toxic event, and this was confirmed in the subsequent knockdown experiment. Moreover, molecular docking studies and forkhead box O1 (foxO1) transcription factor inhibitor (AS1842856) exposure experiments demonstrated that the blockade of foxO1 transcriptional regulation was responsible for the decreased expression of ripor2. The results of this study demonstrated that the occurrence of developmental malformation and mortality in zebrafish offspring embryos following maternal TDtBPP exposure were triggered by the blockade of foxO1 transcriptional regulation and the consequent down-regulation of ripor2.

GC-MS Analysis of Polysaccharides from an Intergeneric Hybrid of Pleurotus florida and Cordyceps militaris: A Comparative Study

Edible and medicinal mushrooms are valuable sources of polysaccharides, known for their dual roles as immunostimulants and immunosuppressants. This study aimed to enhance polysaccharide content by fusing two mushroom species, P. florida and C. militaris, while exploring their antioxidant and antibacterial potential. These mushrooms have diverse health benefits, including lowering high cholesterol, providing anti-inflammatory effects, supporting diabetes management, aiding in cancer treatment, and enhancing the efficacy of COVID-19 vaccines. Successful hyphal fusion was achieved, and optimal culture conditions were determined using response surface methodology. The hybrids exhibited superior growth compared to the parental strains. Hyphal fusion improved several attributes, resulting in diverse hybrids with increased biomass and metabolite production. FTIR analysis confirmed the presence of exopolysaccharides, with concentrations measured at 28.4 g/L (P1), 31.50 g/L (CD), and 36.74 g/L (F3). GC-MS analysis identified various bioactive metabolites, including a higher concentration of dimethyl palmitamine in the hybrid, a novel compound, butanenitrile, 2-(methoxymethoxy), which was not found in the parental strains. These compounds are likely responsible for the enhanced antimicrobial and antioxidant activities.

Inferring atmospheric sources of gaseous organophosphate esters from spatial patterns

Organophosphate esters (OPEs) have emerged as pervasive environmental contaminants, with concentrations often exceeding those of traditional flame retardants and plasticizers by orders of magnitude. Here, we present concentrations of OPEs in the atmospheric gas phase collected using passive air samplers deployed in the coastal regions of Quebec and British Columbia in southern Canada. Four OPEs, i.e., tri-n-butyl phosphate (TBP), tris(2-chloroethyl) phosphate (TCEP), tris(1-chloro-2-propyl) phosphate (TCPP), and tris (phenyl) phosphate (TPhP) were reliably and ubiquitously detected, with TCPP showing the highest level, followed by TBP. Concentration levels of TCPP and TCEP are correlated with each other and with population, possibly indicating emission from consumer products. Spatial patterns of TBP and TPhP are more indicative of industrial usage, with airports possibly being a major source for TBP. The positive relationships between atmospheric OPEs and population are influenced by ambient temperature, whereby the size of the populated area around a sampling site influencing the air concentration appears to be decreasing at higher temperatures.

Recent Advances in the Synthesis of Commercially Available Phosphite Antioxidants

Phosphite antioxidants exhibit superior anti-aging and color-stabilizing properties when incorporated into polymer materials. Their synergistic antioxidative effects are particularly noteworthy when used in combination with hindered phenol antioxidants and other primary antioxidants, serving as effective secondary antioxidants, displaying noteworthy synergistic antioxidation effects. This review systematically classifies the synthetic methods for phosphite antioxidants into three distinct categories based on the types of starting materials: synthesis from phosphorus trichloride, phosphorus-containing esters, and white phosphorus. Additionally, it delineates the reaction mechanisms associated with these approaches and provides an overview of future potential research directions and applications for organophosphorus antioxidants.

Chemical Dissipation from Outdoor Plastics: The Significant Impact of Transformation Processes Revealed by Adjusted Mass Transfer Modeling

Chemicals in plastics raise significant concerns for potential adverse environmental and health impacts. However, dissipation kinetics and fluxes of chemicals from outdoor plastic products remain largely uncharacterized, hindering the accurate assessment of their environmental exposure. This study quantified outdoor dissipation profiles for 20 "priority" chemicals, including sunscreens (benzophenone, benzophenone-3, octyl salicylate, etc.), phthalates, benzotriazole ultraviolet stabilizers (UV-P, UV-326, UV-327, etc.), and polycyclic aromatic hydrocarbons (PAHs), from 3 types of plastic protective nets over 180 days. Results revealed that levels of sunscreens and PAHs decreased to less than 50% of their initial concentrations within 5 days. Adjusted mass transfer modeling by integrating transformation processes well reproduced the dissipation kinetics (median determination coefficients R2 = 0.82) and revealed synchronous release and transformation in the dissipation. Average dissipation half-lives of the chemicals were 19.7 days and positively correlated with the number of electron lone pairs and carbon atoms in the molecules. Unexpectedly, the transformation contributed 82.1% to the total chemical dissipation, especially for di(2-ethylhexyl) phthalate (DEHP) and UV-326. Suspect screening of formed products in PPNs suggested photolysis, ozone, and hydroxyl radical-induced oxidation as the primary transformation processes, supported by a high concentration of 2-ethylhexyl benzoate product comparable to its parent DEHP. These insights underscore the pivotal role of transformation in chemical dissipation from plastics, informing more precise emission assessment of chemicals and future efforts toward developing environmentally benign plastics.

Target and Nontarget Analysis of Organophosphorus Flame Retardants and Plasticizers in a River Impacted by Industrial Activity in Eastern China

Industrial activities are a major source of organophosphorus flame retardants (OPFRs) and plasticizers in aquatic environments. This study investigated the distribution of 40 OPFRs in a river impacted by major industrial manufacturing plants in Eastern China by target analysis. Nontarget analysis using high-resolution mass spectrometry was further employed to identify novel organophosphorus compounds (NOPs). Thirty-four OPFRs were detected in river water samples, with total concentrations of 62.9-1.06 × 103 ng/L (median: 455 ng/L). Triphenylphosphine oxide and diphenyl phosphoric acid were ubiquitously detected up to 620 and 127 ng/L, respectively. Among 26 identified NOPs, 17 were reported for the first time in the environment, including 14 novel organophosphate esters (especially 4 heterocycles and 3 oligomers), 2 organophosphites, and an organophosphonate. Bis(2,4-di-tert-butylphenyl) hydrogen phosphate and 2,2-dimethylpropoxy(propyl)phosphinic acid with high predicted persistence or toxicity were widely detected, with semiquantified concentrations up to 990 and 1.0 × 103 ng/L, respectively. Structurally similar organophosphorus heterocycles exhibited consistent variation trends, suggesting a common emission source. Estimated annual river discharges to the sea were 20.6-37.0 kg/yr for OPFRs and 30.8-161 kg/yr for NOPs. These findings indicate that industrial activities contribute OPFRs and NOPs to the river catchment and its estuary, posing ecological risks to both terrestrial and marine environments.

A Novel Organophosphate Ester, Tris(2,4-ditert-butylphenyl) Phosphate, Induced Reproductive Toxicity in Male Zebrafish at Environmentally Relevant Concentrations

As a novel organophosphate ester (NOPE), tris(2,4-ditert-butylphenyl) phosphate (TDtBPP) has attracted significant attention due to its unexpectedly high detection in natural environments. However, the ecological toxic effects of environmentally relevant concentrations of TDtBPP in organisms remain entirely unknown. In this study, 1 month old zebrafish were exposed to 0, 50, 500, or 5000 ng/L TDtBPP for 150 days, and the reproductive toxicity in male fish was evaluated. Results demonstrated that TDtBPP exposure significantly inhibited the maturation of spermatozoa and thus decreased spermatogenesis. Furthermore, abnormal sperm morphology and decreased sperm motility were also observed. The decrease in sperm quantity and quality eventually resulted in the declining fecundity. Moreover, TDtBPP exposure downregulated the expression of hsd3b1 in vivo and in vitro and subsequently inhibited the synthesis of androgens in zebrafish testes and Leydig cells. This inhibition of androgen synthesis appeared to be responsible for the observed reproductive toxicity in male fish. Molecular docking and dual-luciferase reporter gene experiments elucidated that TDtBPP inhibited the promotion of vitamin D on hsd3b1 transcription by the vitamin D receptor and thus downregulated the expression of hsd3b1. Our findings provide first time evidence that TDtBPP poses a risk to male fish reproduction at environmentally relevant levels.

Novel organophosphate esters and their transformation products in offshore sediment from Eastern China: Occurrence, temporal trend, and risk assessment

Offshore sediment serves as an important sink for traditional organophosphate esters (TOPEs) originating from terrestrial sources. However, the contamination characteristics of novel OPEs (NOPEs) and their hydrolyzed and hydroxylated transformation products (Di- and OH-OPEs) in marine sediment are still unknown. In this study, 34 OPE-associated contaminants were measured in six offshore sediment cores (71 samples) collected from Eastern China. The total concentrations of Σ15TOPEs, Σ3NOPEs, Σ9Di-OPEs, and Σ7OH-OPEs in surface sediments were 3.16-73.4, n.d.-16.3, 4.48-21.4, and 0.14-0.42 ng g-1, respectively. NOPE compounds, such as tris(2,4-di-tert-butylphenyl) phosphate and its diester product, exhibited high contamination levels, primarily due to their high hydrophobicity and extensive industrial applications. Additionally, atmospheric transportation, along with wet and dry deposition and ocean currents, plays a crucial role in their distribution in offshore sediment. The location conditions and historical usage also influenced the vertical distributions of OPE-associated contaminants in sediment cores. Notably, a concentration peak of bis(2,4-di-tert-butylphenyl) phosphate (B2,4DtBPP) was dating back to 1940s, indicating the early usage of antioxidant tris(2,4-di-tert-butylphenyl) phosphite. Furthermore, a risk quotient (RQ) model was employed to assess the ecological risks posed by OPEs. Generally, the acute toxicity-based predicted no-effect concentrations for studied compounds were 1 to 2 orders of magnitude lower than those based on chronic toxicity. NOPEs and B2,4DtBPP exhibited high ecological risks, with maximum RQ values of 1570-4877 based on acute toxicity and 93.4-197 based on chronic toxicity. Notably, ΣRQ values for NOPEs were significantly higher than those of TOPEs (Mann-Whitney U test, p < 0.001), indicating their severe ecological risks in offshore sediment. Therefore, given the continuous input and considerable persistence of NOPEs in offshore sediment, their toxic effects and mechanisms warrant thorough investigation. This study provides the first evidence for the occurrence, temporal trends, and potential risks of NOPEs in marine sediment environment.

First Evidence of Novel Organothiophosphate Esters as Prevalent New Pollutants in Dust from Automotive Repair Shops Discovered by High-Resolution Mass Spectrometry

The occurrence of organophosphorus compounds has garnered global concern due to their widespread production and potential environmental risks. Limited structural information has hindered a comprehensive understanding of their composition. By characteristic fragmentation-based nontarget analysis, the occurrence and composition of organothiophosphate esters (OTPEs), which are antiwear additives in lubricant oils that have received little attention previously, were investigated in dust from automotive repair shops and surrounding buildings. Fourteen OTPEs were tentatively identified, including four triarylphosphorothionates, six O,O-dialkyl phosphorothioates, and four O-alkyl O-alkyl sulfone phosphorothioates, among which four OTPEs were further confirmed by authentic standards or an industrial product. Triphenyl phosphorothioate (TPhPt) and tris(2,4-di-tert-butylphenyl) phosphorothioate (AO168=S) were prevalently detected in automotive repair shops with median concentrations of 230 and 246 ng/g, respectively, closely comparable to triphenyl phosphate (TPhP, median concentration: 302 ng/g). O,O-Dihexyl phosphorothioate (DHPt), O,O-dioctyl phosphorothioate (DOPt), O-hexyl O-hexyl sulfone phosphorothioate (DHSPt), and O-octyl O-octyl sulfone phosphorothioate (DOSPt) were the abundant analogues in automotive repair shops with semiquantitative median concentrations in the range of 119-1.05 × 103 ng/g. Hierarchical cluster analysis showed that OTPEs exhibited similar distribution patterns across automotive repair shops, indicating that these chemicals had similar sources. Moreover, the concentrations of OTPEs were usually higher in automotive repair shops than that in surrounding buildings, suggesting a motor vehicle related emission source. To our knowledge, 12 out of the 14 detected OPTEs were reported in the environment for the first time. The discovery of these OTPEs expanded the scope of known organophosphorus pollutants, highlighting the potential contaminants of OTPEs from lubricant oils for automotive and industrial applications.

Nationwide human biomonitoring strategy in Korea: Prioritization of novel contaminants using GC/TOF-MS with suspect and non-target screening

According to global regulations on hazardous chemicals, numerous alternatives have been manufactured and used in various consumer products. Suspect and non-target analyses are advanced analytical techniques used for identifying novel contaminants. In the present study, suspect and non-target analytical approaches using a gas chromatography coupled to a time-of-flight mass spectrometer were applied to identify novel contaminants in 40 pooled serum samples from a sub-population (n = 400) of the 2015-2017 national biomonitoring program. Suspect screening analysis was performed using an in-house library based on retention times and quantifier and qualifier ions for 222 contaminants, including persistent organic pollutants and emerging contaminants. Non-target analysis was performed by matching deconvoluted mass spectra to the spectral library from the National Institute of Standards and Technology. The suspect screening analysis identified organochlorinated pesticides, organophosphate esters, phthalate esters, and alternative plasticizers. Among the 68 compounds identified in the non-target analysis, siloxanes, novel organophosphate esters, and UV ink photoinitiators were considered candidates for future inclusion in the biomonitoring program based upon significant human exposure. Our findings demonstrate the feasibility of suspect and non-target analysis to identify novel contaminants to prioritize for inclusion within a national human biomonitoring program.

Nationwide profiling and source identification of organophosphate esters in Korean surface waters using target, suspect, and non-target HRMS analysis

Organophosphate esters (OPEs) are emerging contaminants that serve as alternatives to regulated substances in aquatic environments. A nationwide large-scale assessment for OPEs, including point sources, remains insufficient. To address this issue, we aimed to investigate OPEs occurrence and novel OPEs via comprehensive target, suspect and non-target analysis. Among the 11 target OPEs, 10 were detected at sampling sites distributed evenly nationwide. The highest mean concentrations were measured for tris-(2-butoxyethyl) phosphate (TBOEP) and tris(2-chloroisopropyl) phosphate (TCIPP). The multivariate statistical analysis revealed that TBOEP and TCIPP are essential components for assessing total OPEs pollution. The systematic risk assessment results evaluated the overall risk contribution of TBOEP and the significant risk impact of 2-ethylhexyl diphenyl phosphate. Promising suspect and non-target analysis enabled frequent detection and identification of 6 antioxidant transformation products (TPs), as well as the tentative identification of 14 OPEs and TPs, including 3 di-OPEs. Based on sampling site classification, we confirmed that major OPEs are significantly discharged near point sources. We believe that this is the first attempt to assess the nationwide risk and potential sources of OPEs in Korean surface waters, providing insights that could support further prioritization and regulation efforts.

Regulation of Ocean Surface Currents and Seasonal Sea Ice Variations on the Occurrence and Transport of Organophosphate Esters in the Central Arctic Ocean

Organophosphate esters (OPEs) have been observed in the remote Arctic Ocean, yet the influence of hydrodynamics and seasonal sea ice variations on the occurrence and transport of waterborne OPEs remains unclear. This study comprehensively examines OPEs in surface seawater of the central Arctic Ocean during the summer of 2020, integrating surface ocean current and sea ice concentration data. The results confirm significant spatiotemporal variations of the OPEs, with the total concentration of seven major OPEs averaging 780 ± 970 pg/L. Chlorinated OPEs, particularly tris(1-chloro-2-propyl) phosphate (TCPP), were dominant. The significant impact of hydrodynamics on the OPE transport is demonstrated by higher OPE concentrations in regions with strong surface currents, especially at the edge of the Beaufort Gyre and the confluence of the Beaufort Gyre and the Transpolar Drift. Furthermore, OPE levels were generally higher in drifting-ice-covered regions compared to ice-free regions, attributed to the volatilization of dissolved OPEs formerly trapped below the sea ice or newly released from melting snow and sea ice. Notably, TCPP decreased by only 19% in the ice-free area, while the more volatile triphenyl phosphate decreased by 63% compared with the partial ice region.

Emerging investigator series: in-depth chemical profiling of tire and artificial turf crumb rubber: aging, transformation products, and transport pathways

Crumb rubber generated from end-of-life tires (ELTs) poses a threat to environmental and human health based on its widespread use. Of particular concern is the use of ELT crumb rubber as infill for artificial turf fields, as people are unknowingly exposed to complex mixtures of chemicals when playing on these fields. Additionally, there is concern regarding transport of rubber-related chemicals from artificial turf into the environment. However, existing knowledge does not fully elucidate the chemical profile, transformation products, and transport pathways of artificial turf crumb rubber across different ages. To address these knowledge gaps, we utilized a multi-faceted approach that consisted of targeted quantitation, chemical profiling, and suspect screening via ultra-high performance liquid chromatography-high-resolution mass spectrometry (UHPLC-HRMS). We collected and processed 3 tire and 11 artificial turf crumb rubber samples via solvent extraction, leaching, and a bioaccessibility-based extraction. Nineteen rubber-derived chemicals were quantified using parallel reaction monitoring and isotope dilution techniques. In solvent extracts, the most abundant analytes were 1,3-diphenylguanidine (0.18-1200 μg g-1), N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD, 0.16-720 μg g-1), 2-mercaptobenzothiazole (0.47-140 μg g-1), and benzothiazole (0.84-150 μg g-1). Chemical profiling assessed changes in sample diversity, abundance, polarity, and molecular mass. Suspect screening identified 81 compounds with different confidence levels (16 at level 1, 53 with level 2, 7 at level 3, and 5 at level 4). The formation rate of transformation products and clustering analysis results identified time-based trends in artificial turf field samples. We found that the first two years of aging may be critical for the potential environmental impact of artificial turf fields. Our analysis provides insight into the chemical complexity of artificial turf crumb rubber samples ranging from 0-14 years in age.

Organophosphate Esters in Raw Cow Milk and Cow's Drinking Water and Feed from China: Occurrence, Regional Distribution, and Dietary Exposure Assessment

Organophosphate esters (OPEs) have been widely produced and used, while little is known about their occurrence in the food chain and potential sources. In this study, raw cow milk, cow drinking water, and feed were collected from pastures across China, and OPEs were tested to explore the occurrence and transmission of OPEs in the food chain and to further assess daily OPE intakes for cows and humans via certain food consumption. The median level of ∑OPEs (sum of 15 OPEs) in raw milk was 2140 pg/mL, and tris(1-chloro-2-propyl) phosphate (TCIPP) was the most abundant OPE. Levels of OPEs in water were lower than those in raw milk except for triethyl phosphate (TEP), while levels of most OPEs in feed were significantly higher than those in raw milk (adjusted by dry weight). The estimated dietary intake of OPEs via feed for cows was 2530 ng/kg bw/day, which was much higher than that via water (742 ng/kg bw/day), indicating that feed was a more critical exposure source. For liquid milk consumers, the high-exposure (95th) estimated daily intakes (EDIs) of ∑15OPE were 20 and 7.11 ng/kg bw/day for 3-17 years and adults, respectively, and it is obvious that cows had much heavier OPE intake. Finally, the calculated hazard indexes (HIs) suggested that the intake of OPEs via cow milk consumption would not pose significant health risks to the Chinese population.

Integration of Nontarget Screening and QSPR Models to Identify Novel Organophosphate Esters of High Priority in Aquatic Environment

With the development of large numbers of novel organophosphate esters (OPEs) alternatives, it is imperative to screen and identify those with high priority. In this study, surface water, biofilms, and freshwater snails were collected from the flow-in rivers of Taihu Lake Basin, China. Screened by target, suspect, and nontarget analysis, 11 traditional and 14 novel OPEs were identified, of which 5 OPEs were first discovered in Taihu Lake Basin. The OPE concentrations in surface water ranged from 196 to 2568 ng/L, with the primary homologue tris(2,4-ditert-butylphenyl) phosphate (TDtBPP) being newly identified, which was likely derived from the transformation of tris(2,4-ditert-butylphenyl) phosphite. The majority of the newly identified OPEs displayed substantially higher bioaccumulation and biomagnification potentials in the biofilm-snail food chain than the traditional ones. Quantitative structure-property relationship models revealed both hydrophobicity and polarity influenced the bioaccumulation and biomagnification of the OPEs, while electrostatic attraction also had a contribution to the bioaccumulation in the biofilm. TDtBPP was determined as the utmost priority by toxicological priority index scheme, which integrated concentration, bioaccumulation, biomagnification, acute toxicity, and endocrine disrupting potential of the identified OPEs. These findings provide novel insights into the behaviors of OPEs and scientific bases for better management of high-risk pollutants in aquatic ecosystem.

Contamination of dairy products with tris(2,4-di-tert-butylphenyl) phosphite and implications for human exposure

Tris(2,4-di-tert-butylphenyl) phosphite (AO168), an organophosphite antioxidant, can be oxidized to tris(2,4-di-tert-butylphenyl) phosphate (AO168 = O) during the production, processing, and application of plastics. AO168 = O can be further transformed to bis(2,4-di-tert-butylphenyl) phosphate and 2,4-di-tert-butylphenol. Here, we discovered the contamination of AO168 and its transformation products in dairy products for the first time. More samples contained AO168 (mean concentration: 8.78 ng/g wet weight [ww]), bis(2,4-di-tert-butylphenyl) phosphate (mean:11.1 ng/g ww) and 2,4-di-tert-butylphenol (mean: 46.8 ng/g ww) than AO168 = O (mean: 40.2 ng/g ww). The concentrations of AO168 and its transformation products were significantly correlated, and differed with the packaging material and storage conditions of the product. Estimated daily intakes (EDIs) of AO168 and its transformation products were calculated. Although the overall dietary risks were below one, transformation products accounted for 96.7% of the total hazard quotients. The high-exposure EDIs of total AO168 were above the threshold of toxicological concern (300 ng/kg bw/day), and deserve continual monitoring.

Aggravating Pollution of Emerging Aryl Organophosphate Esters in Urban Estuarine Sediments of South China

Emerging aryl organophosphate esters (aryl-OPEs) have been employed as substitutes for organohalogen flame retardants in recent years; however, their environmental occurrence and associated impacts in urban estuarine sediments have not been adequately investigated, impeding regulatory decision-making. Herein, field-based investigations and modeling based on surface sediment and sediment core analysis were employed to uncover the historical pollution and current environmental impacts of aryl-OPEs in the Pearl River Estuary, South China. Our results revealed a substantial increase in aryl-OPE emission, particularly emerging aryl-OPEs, through sediment transport to the estuary since the 2000s. The emerging aryl-OPEs comprised 83% of the total annual input in the past decade, with an average annual input of 155,000 g. Additionally, the emerging-to-traditional aryl-OPE concentration ratios increased with decreasing distance from the shore, peaking in the highly urbanized riverine outlets. These findings indicate that inventories of emerging aryl-OPEs are likely increasing in estuarine sediments and their emissions are surpassing those of traditional aryl-OPEs. Our risk-based priority screening approach indicates that some emerging aryl-OPEs, particularly bisphenol A bis(diphenyl phosphate), can pose a higher environmental risk than traditional aryl-OPEs in estuarine sediments. Overall, our study highlights the importance of recognizing the environmental impacts of emerging aryl-OPEs.

Polymer chain extenders induce significant toxicity through DAF-16 and SKN-1 pathways in Caenorhabditis elegans: A comparative analysis

Polymer chain extenders, commonly used in plastic production, have garnered increasing attention due to their potential environmental impacts. However, a comprehensive understanding of their ecological risks remains largely unknown. In this study, we employed the model organism Caenorhabditis elegans to investigate toxicological profiles of ten commonly-used chain extenders. Exposure to environmentally relevant concentrations of these chain extenders (ranging from 0.1 µg L-1 to 10 mg L-1) caused significant variations in toxicity. Lethality assays demonstrated the LC50 values ranged from 92.42 µg L-1 to 1553.65 mg L-1, indicating marked differences in acute toxicity. Sublethal exposures could inhibit nematodes' growth, shorten lifespan, and induce locomotor deficits, neuronal damage, and reproductive toxicity. Molecular analyses further elucidated the involvement of the DAF-16 and SKN-1 signaling pathways, as evidenced by upregulated expression of genes including ctl-1,2,3, sod-3, gcs-1, and gst-4. It implicates these pathways in mediating oxidative stress and toxicities induced by chain extenders. Particularly, hexamethylene diisocyanate and diallyl maleate exhibited markedly high toxicity among the chain extenders, as revealed through a comparative analysis of multiple endpoints. These findings demonstrate the potential ecotoxicological risks of polymer chain extenders, and suggest the need for more rigorous environmental safety assessments.

Identification and Prioritization of Organic Pollutants in Human Milk from the Yangtze River Delta, China

Pollutants in human milk are critical for evaluating maternal internal exposure and infant external exposure. However, most studies have focused on a limited range of pollutants. Here, 15 pooled samples (prepared from 467 individual samples) of human milk from three areas of the Yangtze River Delta (YRD) in China were analyzed by gas chromatography quadrupole time-of-flight mass spectrometry. In total, 171 compounds of nine types were preliminarily identified. Among these, 16 compounds, including 2,5-di-tert-butylhydroquinone and 2-tert-butyl-1,4-benzoquinone, were detected in human milk for the first time. Partial least-squares discriminant analysis identified ten area-specific pollutants, including 2-naphthylamine, 9-fluorenone, 2-isopropylthianthrone, and benzo[a]pyrene, among pooled human milk samples from Shanghai (n = 3), Jiangsu Province (n = 6), and Zhejiang Province (n = 6). Risk index (RI) values were calculated and indicated that legacy polycyclic aromatic hydrocarbons (PAHs) contributed only 20% of the total RIs for the identified PAHs and derivatives, indicating that more attention should be paid to PAHs with various functional groups. Nine priority pollutants in human milk from the YRD were identified. The most important were 4-tert-amylphenol, caffeine, and 2,6-di-tert-butyl-p-benzoquinone, which are associated with apoptosis, oxidative stress, and other health hazards. The results improve our ability to assess the health risks posed by pollutants in human milk.

Tris (2-chloroisopropyl) phosphate and Tris (nonylphenyl) phosphite Promote Human Renal Cell Apoptosis through the ERK/CEPBA/Long Non-Coding RNA Cytoskeleton Regulator Axis

Organophosphorus compounds (OPs) are widely used and have the potential to be harmful environmental toxicants to humans. Long non-coding RNA (lncRNA) plays a crucial regulatory role in cytotoxicity. This study aimed to investigate the effects of OPs on the expression of lncRNAs in cells. The effects of the industrial OPs TNPP and TCPP on both CYTOR and cellular viability were examined in the following human renal cell lines: HEK293T and HK-2. Both TCPP and TNPP downregulated CYTOR expression, increased reactive oxygen species levels, and induced apoptosis; the upregulated expression of CYTOR resulted in a reduction in apoptosis. The results of the luciferase reporter assay and the knock-down assay indicate that CEBPA binds to the upstream promoter region of CYTOR and regulates its transcription. Furthermore, TCPP and TNPP were found to downregulate the phosphorylation of ERK in the signaling pathway that is upstream of CEBPA. These results indicate that TCPP and TNPP can decrease the level of CEBPA by reducing ERK phosphorylation; this leads to a decrease in CYTOR expression, which further promotes cellular reactive oxygen species and apoptosis. Therefore, the ERK/CEBPA/CYTOR axis is one of the pathways by which organophosphates produce cytotoxicity, leading to renal cell injury. This study presents evidence for both the abnormal expression of lncRNA that is caused by organophosphates and the regulatory function of lncRNA regarding downstream cellular viability.

Contamination Status of Novel Organophosphate Esters Derived from Organophosphite Antioxidants in Soil and the Effects on Soil Bacterial Communities

The contamination status of novel organophosphate esters (NOPEs) and their precursors organophosphite antioxidants (OPAs) and hydroxylated/diester transformation products (OH-OPEs/di-OPEs) in soils across a large-scale area in China were investigated. The total concentrations of the three test NOPEs in soil were 82.4-716 ng g-1, which were considerably higher than those of traditional OPEs (4.50-430 ng g-1), OPAs (n.d.-30.8 ng g-1), OH-OPEs (n.d.-0.49 ng g-1), and di-OPEs (0.57-21.1 ng g-1). One NOPE compound, i.e., tris(2,4-di-tert-butylphenyl) phosphate (AO168 = O) contributed over 65% of the concentrations of the studied OPE-associated contaminants. A 30-day soil incubation experiment was performed to confirm the influence of AO168 = O on soil bacterial communities. Specific genera belonging to Proteobacteria, such as Lysobacter and Ensifer, were enriched in AO168 = O-contaminated soils. Moreover, the ecological function of methylotrophy was observed to be significantly enhanced (t-test, p < 0.01) in soil treated with AO168 = O, while nitrogen fixation was significantly inhibited (t-test, p < 0.01). These findings comprehensively revealed the contamination status of OPE-associated contaminants in the soil environment and provided the first evidence of the effects of NOPEs on soil microbial communities.

Acute exposure to tris(2,4-di-tert-butylphenyl)phosphate elicits cardiotoxicity in zebrafish (Danio rerio) larvae via inducing ferroptosis

Tris(2,4-di-tert-butylphenyl)phosphate (AO168 =O), a novel organophosphate ester, is prevalent and abundant in the environment, posing great exposure risks to ecological and public health. Nevertheless, the toxicological effects of AO168 =O remain entirely unknown to date. The results in this study indicated that acute exposure to AO168 =O at 10 and 100 μg/L for 5 days obviously impaired cardiac morphology and function of zebrafish larvae, as proofed by decreased heartbeat, stroke volume, and cardiac output and the occurrence of pericardial edema and ventricular hypertrophy. Transcriptomics, polymerase chain reaction, and molecular docking revealed that the strong interaction of AO168 =O and transferrin receptor 1 activated the transportation of ferric iron into intracellular environment. The release of free ferrous ion to cytoplasmic iron pool also contributed to the iron overload in heart region, thus inducing ferroptosis in larvae via generation of excessive reactive oxygen species, glutathione peroxidase 4 inhibition, glutathione depletion and lipid peroxidation. Ferroptosis inhibitor (Fer-1) co-exposure effectively relieved the cardiac dysfunctions of zebrafish, verifying the dominant role of ferroptosis in the cardiotoxicity caused by AO168 =O. This research firstly reported the adverse impact and associated mechanisms of AO168 =O in cardiomyogenesis of vertebrates, underlining the urgency of concerning the health risks of AO168 =O.

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.

Occurrence, potential sources, and ecological risks of traditional and novel organophosphate esters in facility agriculture soils: A case study in Beijing, China

Although traditional organophosphate esters (OPEs) in soils have attracted widespread interest, there is little information on novel OPEs (NOPEs), especially in facility agriculture soils. In this work, we surveyed 11 traditional OPEs, four NOPEs, and four corresponding organophosphite antioxidant precursors (OPAs) for the NOPEs in soil samples collected from facility greenhouses and open fields. The median summed concentrations of traditional OPEs and NOPEs were 14.1 μg/kg (range: 5.38-115 μg/kg) and 702 μg/kg (range: 348-1952 μg/kg), respectively, in film-mulched soils from greenhouses. These concentrations were much higher than those in soils without mulch films, which suggests that OPEs in soils are associated with plastic mulch films. Tris(2,4-di-tert-butylphenyl) phosphate, which is a NOPE produced by oxidation of (2,4-di-tert-butylphenyl) phosphite, was the predominant congener in farmland soils, with concentrations several orders of magnitude greater than those of traditional OPEs. Comparisons of OPEs in different mulch films and the corresponding mulched soils revealed that degradable and black films caused more severe pollution than polyethylene and white films. Traditional OPEs, including tris(2-ethylhexyl) phosphate and tricresyl phosphate, exhibited moderate risks in farmland soils, especially in film-mulched soils. NOPEs, including trisnonylphenol phosphate, posed high ecological risks to the terrestrial ecosystem. Risk evaluations should be conducted for a broad range of NOPEs in the environment.

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

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

The hidden diet: Synthetic antioxidants in packaged food and their impact on human exposure and health

Synthetic antioxidants (AOs) are commonly used in everyday items and industrial products to inhibit oxidative deterioration. However, the presence of AOs in food packaging and packaged foods has not been thoroughly documented. Moreover, studies on human exposure to AOs through skin contact with packaging or ingesting packaged foods are limited. In this study, we analyzed twenty-three AOs-including synthetic phenolic antioxidants (SPAs) and organophosphite antioxidants (OPAs)-along with six transformation products in various food samples and their packaging materials. We found AOs in food products at concentrations ranging from 1.30 × 103 to 1.77 × 105 ng/g, which exceeded the levels in both outer packaging (6.05 × 102-3.07 × 104 ng/g) and inner packaging (2.27 × 102-1.09 × 105 ng/g). The most common AOs detected in foodstuffs were tris(2,4-di-tert-butylphenyl) phosphate (AO168O), butylated hydroxytoluene (BHT), and octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (AO1076), together constituting 95.7 % of the total AOs found. Our preliminary exposure assessment revealed that dietary exposure-estimated at a median of 2.55 × 104 ng/kg body weight/day for children and 1.24 × 104 ng/kg body weight/day for adults-is a more significant exposure route than dermal contact with packaging. Notably, four AOs were identified in food for the first time, with BHT making up 76.8 % and 67.6 % of the total BHT intake for children and adults, respectively. These findings suggest that food consumption is a significant source of BHT exposure. The estimated daily intakes of AOs via consumption of foodstuffs were compared with the recommended acceptable daily intake to assess the risks. This systematic investigation into AOs contributes to understanding potential exposure and health risks associated with AOs in packaged foods. It emphasizes the need for further evaluation of human exposure to these substances.

Identification, semi-quantification and risk assessment of contaminants of emerging concern in Flemish indoor dust through high-resolution mass spectrometry

Indoor dust can contribute substantially to human exposure to known and contaminants of emerging concern (CECs). Novel compounds with high structural variability and different homologues are frequently discovered through screening of the indoor environment, implying that constant monitoring is required. The present study aimed at the identification and semi-quantification of CECs in 46 indoor dust samples collected in Belgium by liquid chromatography high-resolution mass spectrometry. Samples were analyzed applying a targeted and suspect screening approach; the latter based on a suspect list containing >4000 CECs. This allowed the detection of a total of 55 CECs, 34 and 21 of which were identified with confidence level (CL) 1/2 or CL 3, respectively. Besides numerous known contaminants such as di(2-ethylhexyl) phthalate (DEHP), di(2-ethylhexyl) adipate (DEHA) or tris(2-butoxyethyl) phosphate (TBOEP) which were reported with detection frequencies (DFs) > 90%, several novel CECs were annotated. These included phthalates with differing side chains, such as decyl nonyl and decyl undecyl phthalate detected with DFs >80% and identified through the observation of characteristic neutral losses. Additionally, two novel organophosphate flame retardants not previously described in indoor dust, i.e. didecyl butoxyethoxyethyl phosphate (DDeBEEP) and bis(butoxyethyl) butyl phosphate (BBEBP), were identified. The implementation of a dedicated workflow provided semi-quantitative concentrations for a set of suspects. Such data obtained for novel phthalates were in the same order of magnitude as the concentrations observed for legacy phthalates indicating their high relevance for human exposure. From the semi-quantitative data, estimated daily intakes and resulting hazard quotients (HQs) were calculated to estimate the exposure and potential health effects. Neither of the obtained HQ values exceeded the risk threshold, indicating no expected adverse health effects.

OPEs-ID: A software for non-targeted screening of organophosphate esters based on liquid chromatography-high-resolution mass spectrometry

Organophosphate esters (OPEs) are widely used as flame retardants and plasticizers, presenting a potential threat to the environment and human health. To date, no automatic software exists for the nontargeted screening of OPEs. In this study, OPEs-ID, a user-friendly software, was developed for the identification of OPEs using liquid chromatography-high-resolution mass spectrometry. The main workflow of OPEs-ID included fragments-dependent precursor ion screening, elemental composition determination, extracted ion chromatograms (EIC) comparison, and molecular structure identification via MetFrag strategy. A mixture of 17 OPE standards was identified with an identification rate of 100% by OPEs-ID. OPEs-ID demonstrated a rate of 94.1% for correctly ranking within the top 1 candidate in a local database (41.2% in PubChem) for the 17 OPE standards, which remarkably improved the identification when compared to conventional in silico fragmentation algorithms. Using a pooled airborne fine particle sample (PM2.5), OPEs-ID could automatically retrieve 22 valid molecules with structure candidates. The detection frequencies of 9 newly identified OPEs were between 13% and 100% in the 32 PM2.5 samples. Their semi-quantification concentrations were comparable to those of some traditional OPEs. Overall, OPEs-ID offers a powerful tool to significantly enrich our understanding of the OPEs present in the environment.

A critical review on organophosphate esters in drinking water: Analysis, occurrence, sources, and human health risk assessment

Organophosphate esters (OPEs) are ubiquitous in the environment. Copious studies assessed OPEs in various environmental media. However, there is limited summative information about OPEs in drinking water. This review provides comprehensive data for the analytical methods, occurrence, sources, and risk assessment of OPEs in drinking water. In general, liquid-liquid extraction and solid-phase extraction are the most common methods in the extraction of OPEs from drinking water, while gas chromatography and liquid chromatography are the most commonly used instrumental methods for detecting OPEs in drinking water. On the basis of these techniques, a variety of methods on OPEs pretreatment and determination have been developed to know the pollution situation of OPEs. Studies on the occurrence of OPEs in drinking water show that the total concentrations of OPEs vary seasonally and regionally, with tris(1-chloro-2-isopropyl) phosphate and tris(2-chloroethyl) phosphate dominant among different kinds of drinking water. Source identification studies show that there are three main sources of OPEs in drinking water: 1) source water contamination; 2) residual in drinking water treatment process; 3) leakage from device or pipeline. Besides, risk assessments indicate that individual and total OPEs pose no or negligible health risk to human, but this result may be significantly underestimated. Finally, the current knowledge gaps on the research of OPEs in drinking water are discussed and some suggestions are provided for future environmental research.

Disposable Plastic Waste and Associated Antioxidants and Plasticizers Generated by Online Food Delivery Services in China: National Mass Inventories and Environmental Release

China's online food delivery (OFD) services consume enormous amounts of disposable plastics. Here, we investigated and modeled the national mass inventories and environmental release of plastics and chemical additives in the plastic. The extra-tree regression identified six key descriptors in determining OFD sales in Chinese cities. Approximately 847 kt of OFD plastic waste was generated in 2021 (per capita 1.10 kg/yr in the megacities and 0.39 kg/yr in other cities). Various additives were extensively detected, with geomean concentrations of 140.96, 4.76, and 0.25 μg/g for ∑8antioxidants, ∑21phthalates, and bisphenol A (BPA), respectively. The estimated mass inventory of these additives in the OFD plastics was 164.7 t, of which 51.1 t was released into the atmosphere via incineration plants and 51.0 t was landfilled. The incineration also released 8.07 t of polycyclic aromatic hydrocarbons and 39.1 kt of particulate matter into the atmosphere. Takeout food may increase the dietary intake of phthalates and BPA by 30% to 50% and raise concerns about considerable exposure to antioxidant transformation products. This study provides profound environmental implications for plastic waste in the Chinese OFD industry. We call for a sustainable circular economy action plan for waste disposal, but mitigating the hazardous substance content and their emissions is urgent.

Bringing the emerging organophosphate flame retardants (eOPFRs) into view: A hidden ecological and human health threat

The production and usage of organophosphate flame retardants (OPFRs) in textiles, plastics, and electronics have surged, with phosphorus-based flame retardants constituting over 30 % of the global consumption of flame retardants. Meanwhile, concerns regarding the potential hazards of OPFRs to ecosystems and human health including disruptions in the endocrine system, inhibition of reproduction, and manifestation of developmental defects have intensified. However, our comprehensive data analysis has unveiled a pronounced and critical knowledge gap, as at present, a majority of studies emphasize the attributes of traditional OPFRs, such as triphenyl phosphate (TPHP), while emerging OPFRs (eOPFRs) remain undeservedly overlooked. We elaborated on the current advancements and challenges regarding eOPFRs research and demonstrated that eOPFRs exhibit considerable diversity in terms of their chemical structures, substantial residue levels, broad sources of occurrence, and limited understanding of their potent (eco)toxicological implications. In light of these attributes, it becomes evident that the environmental and health risks of eOPFRs can be comparable to, if not surpass, those attributed to traditional OPFRs. This compelling observation underscores an imperative need for heightened research focus and extensive research efforts dedicated to the study of eOPFRs, rather than still focusing on the realm of their traditional counterparts. Despite the challenges ahead, the emphasized environmental surveillance and toxicological assessment are imperative to prevent the potential evolution of these compounds into a significant ecological and human health threat.

Discovery and occurrence of organophosphorothioate esters in food contact plastics and foodstuffs from South China: Dietary intake assessment

A recent study revealed the presence of non-pesticide organothiophosphate esters (OTPEs) - precursors to organophosphate esters (OPEs) contaminants - in river water. Since OPEs have demonstrated adverse reproductive outcomes in humans, this accentuates the urgency to explore the prevalence of non-pesticide OTPEs in other potential human exposure matrices. In this study, a nontarget screening method based on high-resolution mass spectrometry was used to identify OTPEs in food contact plastic (FCP) samples collected from South China. O,O,O-triphenyl phosphorothioate (TPhPt) and O,O,O-tris(2,4-di-tert-butylphenyl) phosphorothioate (AO168 = S) were unequivocally identified (Level 1), while O,O-di(di-butylphenyl) O-methyl phosphorothioate (BDBPMPt) was tentatively identified (Level 2b, indicating probable structure based on diagnostic evidence). Among n = 70 FCP samples, AO168 = S emerged with the highest detection frequency and median concentration of 74 % and 111 ng/g, respectively. Significant Pearson correlations were observed in log-transformed peak areas of AO168 = S and TPhPt in FCPs with their respective oxons, respectively. Occurrences of AO168 = S and TPhPt were further investigated in n = 100 foodstuff samples using a market basket method. AO168 = S and TPhPt exhibited detection frequencies of 43 % and 44 % in all food items with mean concentrations of 2.17 ng/g wet weight (ww) (range: <0.53-67.8 ng/g ww) and 0.112 ng/g ww (range: <0.006-2.39 ng/g ww), respectively. The highest mean concentrations for AO168 = S and TPhPt were found in vegetables (4.62 ng/g ww) and oil (3.00 ng/g ww), respectively. The median estimated daily intakes (EDIs) of AO168 = S and TPhPt via diet were calculated as 10.4 and 1.51 ng/kg body weight/day, respectively. For AO168 = S, only meat and vegetables contributed to the median EDI, whereas for TPhPt, oil was identified as the principal contributor to the median EDI. This study for the first time evaluated human exposure to OTPEs via diet, providing new insights to overall human exposure to OPEs.

Synthetic Antioxidants as Contaminants of Emerging Concern in Indoor Environments: Knowns and Unknowns

Synthetic antioxidants, including synthetic phenolic antioxidants (SPAs), amine antioxidants (AAs), and organophosphite antioxidants (OPAs), are essential additives for preventing oxidative aging in various industrial and consumer products. Increasing attention has been paid to the environmental contamination caused by these chemicals, but our understanding of synthetic antioxidants is generally limited compared to other emerging contaminants such as plasticizers and flame retardants. Many people spend a significant portion (normally greater than 80%) of their time indoors, meaning that they experience widespread and persistent exposure to indoor contaminants. Thus, this Perspective focuses on the problem of synthetic antioxidants as indoor environmental contaminants. The wide application of antioxidants in commercial products and their demonstrated toxicity make them an important family of indoor contaminants of emerging concern. However, significant knowledge gaps still need to be bridged: novel synthetic antioxidants and their related transformation products need to be identified in indoor environments, different dust sampling strategies should be employed to evaluate human exposure to these contaminants, geographic scope and sampling scope of research on indoor contamination should be broadened, and the partition coefficients of synthetic antioxidants among different media need to be investigated.

Screening of Indoor Transformation Products of Organophosphates and Organophosphites with an in Silico Spectral Database

Numerous transformation products are formed indoors, but they are outside the scope of current chemical databases. In this study, an in silico spectral database was established to screen previously unknown indoor transformation products of organophosphorus compounds (OPCs). An R package was developed that incorporated four indoor reactions to predict the transformation products of 712 seed OPCs. By further predicting MS2 fragments, an in silico spectral database was established consisting of 3509 OPCs and 28,812 MS2 fragments. With this database, 40 OPCs were tentatively detected in 23 indoor dust samples. This is the greatest number of OPCs reported to date indoors, among which two novel phosphonates were validated using standards. Twenty-four of the detected OPCs were predicted transformation products in which oxidation from organophosphites plays a major role. To confirm this, the in silico spectral database was expanded to include organophosphites for suspect screening in five types of preproduction plastics. A broad spectrum of 14 organophosphites was detected, with a particularly high abundance in polyvinyl chloride plastics and indoor end-user goods. This demonstrated the significant contribution of organophosphites to indoor organophosphates via oxidation, highlighting the strength of in silico spectral databases for the screening of unknown indoor transformation products.

High-resolution mass spectrometry-based screening and dietary intake assessment of organophosphate esters in foodstuffs from South China

Organophosphate esters (OPEs) are a group of emerging contaminants with widespread environmental occurrence, yet research on their occurrence in foodstuffs is limited. We collected 100 foodstuff samples in South China using a market basket method, and analyzed food extracts for the presence of OPEs and organophosphite antioxidants (OPAs) by suspect and nontarget screening through high-resolution mass spectrometry. Our analysis resulted in the identification of 30 OPEs, comprised of 25 OPEs with a confidence level (CL) of 1 (unequivocal identification using standards) and five OPEs with CL = 2b (probable structure based on diagnostic evidence). Interestingly, 11 of these identified OPEs had not been previously reported in food. No OPA was identified. The occurrence of identified OPEs within the food samples was further investigated. The highest median concentration of OPEs in all food samples was reached by tris(2-chloroisopropyl) phosphate (TCPP) (1.55 ng/g ww, range < 0.74-12.0 ng/g wet weight (ww)). Cereals demonstrated the highest median concentration of the cumulative 30 OPEs. Tris(2-chloroethyl) phosphate (TCEP), TCPP, and triethyl phosphate (TEP) predominantly contributed to OPEs contamination in most food categories. Eight OPEs, namely TEP, tris(2-ethylhexyl) phosphate (TEHP), TCEP, triphenyl phosphate (TPhP), 2-ethylhexyl diphenyl phosphate (EHDPP), bis(2-ethylhexyl) phenyl phosphate (BEHPP), resorcinol bis(diphenyl phosphate) (RDP), and methyl diphenyl phosphate (MDPP) exhibited significantly higher concentrations in the processed group as compared to non-processed group, suggesting that food processing may result in contamination of these OPEs. The median sum of estimated dietary intake (ΣEDI) of all OPEs was determined to be 161 ng/kg body weight/day. Cereals (38.5 %) and vegetables (23.5 %) were the predominant food categories contributing to ΣEDI, and TEP (29.0 %), TCEP (20.2 %), and TCPP (18.3 %) were three major OPEs contributing to ΣEDI. This study for the first time offered a comprehensive overview of OPE species and revealed their occurrence in foodstuffs from South China.

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

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

Organophosphate esters (OPEs) in a heavily polluted river in South China: Occurrence, spatiotemporal trends, sources, and phase distribution

In the past decade, organophosphate esters (OPEs) undergo rapid increase in production and use. Meanwhile, owing to their additive property, OPEs exhibit liability to escape from related products and therefore ubiquity in various environments. Moreover, numerous researches verify their bioavailability and negative effects on biota and human, hence their occurrence and associated risks have caught much concern, particularly those in aquatic systems. So far, however, OPEs in water are generally investigated as a whole, their phase distribution and behavior in waterbodies are incompletely characterized. We examined 25 OPEs in water (including dissolved and particulate phases), sediment, and sediment core samples from the Lian River, which flows through the Guiyu e-waste recycling zone and Shantou specific economic zone in South China. Compared to most global waterbodies, the Lian River showed high or ultrahigh OPE levels in both water and sediments, particularly in the reaches surrounded by e-waste recycling and plastic-related industries, which were the top two greatest OPE sources. Non-industrial and agriculture-related anthropogenic activities also contributed OPEs. Sediment core data suggested that OPEs have been present in waters in Guiyu since the 1960s and showed a temporal trend consistent with the local waste-recycling business. The phase distribution of OPEs in the Lian River was significantly correlated with their hydrophobicity and solubility. Owing to their wide range of physicochemical properties, OPE congeners showed significant percentage differences in the Lian River water and sediments. Generally, OPEs in water reflect their dynamic real-time inputs, while those in sediment signify their accumulative deposition, which is another cause of their phase distribution disparities in the Lian River. The physicochemical parameters of OPEs first imposed negative and then positive influences on their dissolved phase-sediment distribution, indicating the involvement of both the adsorption of dissolved OPEs and the deposition of particle-bound OPEs.

PM2.5-Bound Organophosphate Flame Retardants in Hong Kong: Occurrence, Origins, and Source-Specific Health Risks

Organophosphate flame retardants (OPFRs) are emerging organic pollutants in PM2.5, which have caused significant public health concerns in recent years, given their potential carcinogenic and neurotoxic effects. However, studies on the sources, occurrence, and health risk assessment of PM2.5-bound OPFRs in Hong Kong are lacking. To address this knowledge gap, we characterized 13 OPFRs in one-year PM2.5 samples using gas chromatography-atmospheric pressure chemical ionization tandem mass spectrometry. Our findings showed that OPFRs were present at a median concentration of 4978 pg m-3 (ranging from 1924 to 8481 pg m-3), with chlorinated OPFRs dominating and accounting for 82.7% of the total OPFRs. Using characteristic source markers and positive matrix factorization, we identified one secondary formation and five primary sources of OPFRs. Over 94.0% of PM2.5-bound OPFRs in Hong Kong were primarily emitted, with plastic processing and waste disposal being the leading source (61.0%), followed by marine vessels (14.1%). The contributions of these two sources to OPFRs were more pronounced on days influenced by local pollution emissions (91.9%) than on days affected by regional pollution (44.2%). Our assessment of health risks associated with human exposure to PM2.5-bound OPFRs indicated a low-risk level. However, further source-specific health risk assessment revealed relatively high noncarcinogenic and carcinogenic risks from chlorinated OPFRs emitted from plastic processing and waste disposal, suggesting a need for more stringent emission control of OPFRs from these sources in Hong Kong.

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

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

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

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

Occurrence and Release of Organophosphite Antioxidants and Novel Organophosphate Esters from Plastic Food Packaging

Organic phosphite antioxidants (OPAs) are widely added in plastic products and can be oxidized to generate oxidized derivatives (OPAs = O), namely organic phosphate esters (OPEs), during production and use processing. Herein, the occurrence of OPEs and OPAs in five plastic food packages was detected by liquid chromatography-tandem mass spectrometry. Three OPEs (TPhP, TCEP, and AO168 = O) and three OPAs (TPhPi, TCEPi, and AO168) were found in the plastic packages, with concentrations of <MQL-124 ng/g (∑₃OPAs) and 196-831 ng/g (∑₃OPEs), respectively. The migration potential of OPAs and OPEs to food was measured by simulation experiments. OPAs and OPEs in plastic can efficiently migrate to oily simulants, alkaline simulants, and acidic simulants. After 14 days, the total concentration of all OPAs and OPEs in the food simulants reached <MQL-1.21 (acidic food simulants), <MQL-0.32 (alkaline food simulants), and 11.4-31.4 ng/mL (oily food simulants), respectively. OPAs and OPEs in 12 kinds of plastic-packaged foods were detected, with high concentrations in dairy food (∑₃OPAs + ∑₃OPEs: 18.3-28.9 ng/mL) and in oils (∑₃OPAs + ∑₃OPEs: 32.7-60.9 ng/mL). Accordingly, the estimated ingestion of OPAs and OPEs through plastic-packaged food can reach 2.6 and 32.7 ng/kg in children and 1.1 and 6.5 ng/kg in adults, indicating a non-negligible exposure risk of organic phosphorus pollutants.

Screening of organophosphate esters in different indoor environments: Distribution, diffusion, and risk assessment

of air conditioner (AC) filter dust can reveal the level of organophosphate ester (OPE) pollution in indoor environments, but comprehensive research on this topic remains lacking. This study combined non-targeted and targeted analysis to screen and analyze 101 samples of AC filter dust, settled dust, and air obtained in 6 indoor environments. Phosphorus-containing organic compounds account for a large proportion of the organic compounds found in indoor environments, and OPEs might be the main pollutants. Using toxicity data and traditional priority polycyclic aromatic hydrocarbons for toxicity prediction of OPEs, 11 OPEs were prioritized for further quantitative analysis. The concentration of OPEs in AC filter dust was highest, followed in descending order by that in settled dust and that in air. The concentration of OPEs in AC filter dust in the residence was two to seven times greater than that in the other indoor environments. More than 56% of the OPEs in AC filter dust showed significant correlation, while those in settled dust and air were weakly correlated, suggesting that large amounts of OPEs collected over long periods could have a common source. Fugacity results showed that OPEs were transferred easily from dust to air, and that dust was the main source of OPEs. The values of both the carcinogenic risk and the hazard index were lower than the corresponding theoretical risk thresholds, indicating low risk to residents through exposure to OPEs in indoor environments. However, it is necessary to remove AC filter dust in a timely manner to prevent it becoming a pollution sink of OPEs that could be rereleased and endanger human health. This study has important implications for comprehensive understanding of the distribution, toxicity, sources, and risks of OPEs in indoor environments.

Organophosphate esters (OPEs) in plastic food packaging: non-target recognition, and migration behavior assessment

Organophosphate esters (OPEs) are widely used as plasticizers in plastic food packaging; however, the migration of OPEs from plastic to food is largely unstudied. We do not even know the specific number of OPEs that exist in the plastic food packaging. Herein, an integrated target, suspect, and nontarget strategy for screening OPEs was optimized using ultrahigh-performance liquid chromatography-high-resolution mass spectrometry (UHPLC-HRMS). The strategy was used to analyze 106 samples of plastic food packaging collected in Nanjing city, China, in 2020. HRMS allowed full or tentative identification of 42 OPEs, of which seven were reported for the first time. Further, oxidation products of bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphite (AO626) in plastics were identified, implying that the oxidation of organophosphite antioxidants (OPAs) could be an important indirect source of OPEs in plastics. The migration of OPEs was examined with four simulated foods. Twenty-six out of 42 OPEs were detected in at least one of the four simulants, particularly isooctane, in which diverse OPEs were detected at elevated concentrations. Overall, the study supplements the list of OPEs that humans could ingest as well as provides essential information regarding the migration of OPEs from plastic food packaging to food.

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.