Monitoring indoor exposure to organophosphate flame retardants: hand wipes and house dust

Children's exposure to halogenated flame retardants and organophosphate esters through dermal absorption and hand-to-mouth ingestion in Swedish preschools

Children are exposed to endocrine disrupting chemicals (EDCs) through inhalation and ingestion, as well as through dermal contact in their everyday indoor environments. The dermal loadings of EDCs may contribute significantly to children's total EDC exposure due to dermal absorption as well as hand-to-mouth behaviors. The aim of this study was to measure potential EDCs, specifically halogenated flame retardants (HFRs) and organophosphate esters (OPEs), on children's hands during preschool attendance and to assess possible determinants of exposure in preschool indoor environments in Sweden. For this, 115 handwipe samples were collected in winter and spring from 60 participating children (arithmetic mean age 4.5 years, standard deviation 1.0) and analyzed for 50 compounds. Out of these, 31 compounds were identified in the majority of samples. Levels were generally several orders of magnitude higher for OPEs than HFRs, and 2-ethylhexyl diphenyl phosphate (EHDPP) and tris(2-butoxyethyl) phosphate (TBOEP) were detected in the highest median masses, 61 and 56 ng/wipe, respectively. Of the HFRs, bis(2-ethyl-1-hexyl)-2,3,4,5-tetrabromobenzoate (BEH-TEBP) and 2,2',3,3',4,4',5,5',6,6'-decabromodiphenyl ether (BDE-209) were detected in the highest median masses, 2.8 and 1.8 ng/wipe, respectively. HFR and/or OPE levels were found to be affected by the number of plastic toys, and electrical and electronic devices, season, municipality, as well as building and/or renovation before/after 2004. Yet, the calculated health risks for single compounds were below available reference dose values for exposure through dermal uptake as well as for ingestion using mean hand-to-mouth contact rate. However, assuming a high hand-to-mouth contact rate, at the 95th percentile, the calculated hazard quotient was above 1 for the maximum handwipe mass of TBOEP found in this study, suggesting a risk of negative health effects. Furthermore, considering additive effects from similar compounds, the results of this study indicate potential concern if additional exposure from other routes is as high.

Unlocking the genomic potential of Red Sea coral probiotics

The application of beneficial microorganisms for corals (BMC) decreases the bleaching susceptibility and mortality rate of corals. BMC selection is typically performed via molecular and biochemical assays, followed by genomic screening for BMC traits. Herein, we present a comprehensive in silico framework to explore a set of six putative BMC strains. We extracted high-quality DNA from coral samples collected from the Red Sea and performed PacBio sequencing. We identified BMC traits and mechanisms associated with each strain as well as proposed new traits and mechanisms, such as chemotaxis and the presence of phages and bioactive secondary metabolites. The presence of prophages in two of the six studied BMC strains suggests their possible distribution within beneficial bacteria. We also detected various secondary metabolites, such as terpenes, ectoines, lanthipeptides, and lasso peptides. These metabolites possess antimicrobial, antifungal, antiviral, anti-inflammatory, and antioxidant activities and play key roles in coral health by reducing the effects of heat stress, high salinity, reactive oxygen species, and radiation. Corals are currently facing unprecedented challenges, and our revised framework can help select more efficient BMC for use in studies on coral microbiome rehabilitation, coral resilience, and coral restoration.

Organophosphate triesters and their diester degradation products in the atmosphere-A critical review

Organophosphate triesters (tri-OPEs) have found substantial use as plasticizers and flame retardants in commercial and industrial products. Despite upcoming potential restrictions on use of OPEs, widespread environmental contamination is likely for the foreseeable future. Organophosphate diesters (di-OPEs) are known biotic or abiotic degradation products of tri-OPEs. In addition, direct use of di-OPEs as commercial products also contributes to their presence in the atmosphere. We review the available data on contamination with tri-OPEs and di-OPEs in both indoor and outdoor air. Concentrations of tri-OPEs in indoor air exceed those in outdoor air. The widespread discovery of tri-OPE traces in polar regions and oceans is noteworthy and is evidence that they undergo long-range transport. There are only two studies on di-OPEs in outdoor air and no studies on di-OPEs in indoor air until now. Current research on di-OPEs in indoor and outdoor air is urgently needed, especially in countries with potentially high exposure to di-OPEs such as the UK and the US. Di-OPE concentrations are higher at e-waste dismantling areas than at surrounding area. We also summarise the methods employed for sampling and analysis of OPEs in the atmosphere and assess the relative contribution to atmospheric concentrations of di-OPEs made by environmental degradation of triesters, compared to the presence of diesters as by-products in commercial triester products. Finally, we identify shortcomings of current research and provide suggestions for future research.

Aromatic amine antioxidants (AAs) and p-phenylenediamines-quinones (PPD-Qs) in e-waste recycling industry park: Occupational exposure and liver X receptors (LXRs) disruption potential

Recently, evidence of aromatic amine antioxidants (AAs) existence in the dust of the electronic waste (e-waste) dismantling area has been exposed. However, there are limited studies investigating occupational exposure and toxicity associated with AAs and their transformation products (p-phenylenediamines-quinones, i.e., PPD-Qs). In this study, 115 dust and 42 hand wipe samples collected from an e-waste recycling industrial park in central China were analyzed for 19 AAs and 6 PPD-Qs. Notably, the median concentration of ∑6PPD-Qs (1,110 ng/g and 1,970 ng/m2) was significantly higher (p < 0.05, Mann-Whitney U test) than that of ∑6PPDs (147 ng/g and 34.0 ng/m2) in dust and hand wipes. Among the detected analytes, 4-phenylaminodiphenylamine quinone (DPPD-Q) (median: 781 ng/g) and 1,4-Bis(2-naphthylamino) benzene quinone (DNPD-Q) (median: 156 ng/g), were particularly prominent, which were first detected in the e-waste dismantling area. Occupational exposure assessments and nuclear receptor interference ability, conducted through estimated daily intake (EDI) and molecular docking analysis, respectively, indicated significant occupational exposure to PPD-Qs and suggested prioritized Liver X receptors (LXRs) disruption potential of PPDs and PPD-Qs. The study provides the first evidence of considerable levels of AAs and PPD-Qs in the e-waste-related hand wipe samples and underscores the importance of assessing occupational exposure and associated toxicity effects.

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

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

Physiologically based toxicokinetic modelling of Tri(2-chloroethyl) phosphate (TCEP) in mice accounting for multiple exposure routes

Exposure routes are important for health risk assessment of chemical risks. The application of physiologically based toxicokinetic (PBTK) models to predict concentrations in vivo can determine the effects of harmful substances and tissue accumulation on the premise of saving experimental costs. In this study, Tri(2-chloroethyl) phosphate (TCEP), an organophosphate ester (OPE), was used as an example to study the PBTK model of mice exposed to different exposure doses by multiple routes. Different routes of exposure (gavage and intradermal injection) can cause differences in the concentration of chemicals in the organs. TCEP that enters the body through the mouth is mainly concentrated in the gastrointestinal tract and liver. However, the concentrations of chemicals that enter the skin into the mice are higher in skin, rest of body, and blood. In addition, TCEP was absorbed and accumulated very rapidly in mice, within half an hour after a single exposure. We have successfully established a mouse PBTK model of the TCEP accounting for multiple exposure Routes and obtained a series of kinetic parameters. The model includes blood, liver, kidney, stomach, intestine, skin, and rest of body compartments. Oral and dermal exposure route was considered for PBTK model. The PBTK model established in this study has a good predictive ability. More than 70% of the predicted values deviated from the measured values by less than 5-fold. In addition, we extrapolated the model to humans. A human PBTK model is built. We performed a health risk assessment for world populations based on human PBTK model. The risk of TCEP in dust is greater through mouth than through skin. The risk of TCEP in food of Chinese population is greater than dust.

Organophosphate ester flame retardants and plasticizers in house dust and mental health outcomes among Canadian mothers: A nested prospective cohort study in CHILD

Organophosphate ester flame retardants and plasticizers (OPEs) are common exposures in modern built environments. Toxicological models report that some OPEs reduce dopamine and serotonin in the brain. Deficiencies in these neurotransmitters are associated with anxiety and depression. We hypothesized that exposure to higher concentrations of OPEs in house dust would be associated with a greater risk of depression and stress in mothers across the prenatal and postpartum periods. We conducted a nested prospective cohort study using data collected on mothers (n = 718) in the CHILD Cohort Study, a longitudinal multi-city Canadian birth cohort (2008-2012). OPEs were measured in house dust sampled at 3-4 months postpartum. Maternal depression and stress were measured at 18 and 36 weeks gestation and 6 months and 1 year postpartum using the Centre for Epidemiologic Studies for Depression Scale (CES-D) and Perceived Stress Scale (PSS). We used linear mixed models to examine the association between a summed Z-Score OPE index and continuous depression and stress scores. In adjusted models, one standard deviation increase in the OPE Z-score index was associated with a 0.07-point (95% CI: 0.01, 0.13) increase in PSS score. OPEs were not associated with log-transformed CES-D (β: 0.63%, 95% CI: -0.18%, 1.46%). The effect of OPEs on PSS score was strongest at 36 weeks gestation and weakest at 1 year postpartum. We observed small increases in maternal perceived stress levels, but not depression, with increasing OPEs measured in house dust during the prenatal and early postpartum period in this cohort of Canadian women. Given the prevalence of prenatal and postpartum anxiety and the ubiquity of OPE exposures, additional research is warranted to understand if these chemicals affect maternal mental health.

An Initial Survey on Occurrence, Fate, and Environmental Risk Assessment of Organophosphate Flame Retardants in Romanian Waterways

Organophosphate ester flame retardants (OPFRs) are ubiquitous organic pollutants in the environment and present an important preoccupation due to their potential toxicity to humans and biota. They can be found in various sources, including consumer products, building materials, transportation industry, electronic devices, textiles and clothing, and recycling and waste management. This paper presents the first survey of its kind in Romania, investigating the composition, distribution, possible sources, and environmental risks of OPFRs in five wastewater treatment plants (WWTPs) and the rivers receiving their effluents. Samples from WWTPs and surface waters were collected and subjected to extraction processes to determine the OPFRs using liquid chromatography with mass spectrometric detection. All the target OPFRs were found in all the matrices, with the average concentrations ranging from 0.6 to 1422 ng/L in wastewater, 0.88 to 1851 ng/g dry weight (d.w.) in sewage sludge, and 0.73 to 1036 ng/L in surface waters. The dominant compound in all the cases was tri(2-chloroisopropyl) phosphate (TCPP). This study observed that the wastewater treatment process was inefficient, with removal efficiencies below 50% for all five WWTPs. The environmental risk assessment indicated that almost all the targeted OPFRs pose a low risk, while TDCPP, TCPP, and TMPP could pose a moderate risk to certain aquatic species. These findings provide valuable information for international pollution research and enable the development of pollution control strategies.

Characterizing azobenzene disperse dyes and related compounds in house dust and their correlations with other organic contaminant classes

Azobenzene disperse dyes are the fastest-growing category of commercial dyestuffs and are implicated in the literature as potentially allergenic. In the indoor environment, these dyes may be shed from various textiles, including clothing and upholstery and accumulate in dust particles potentially leading to exposure in young children who have higher exposure to chemicals associated with dust due to their crawling and mouthing behaviors. Children may be more vulnerable to dye exposure due to their developing immune systems, and therefore, it is critical to characterize azobenzene disperse dyes in children's home environments. Here, we investigate azobenzene disperse dyes and related compounds in house dust samples (n = 124) that were previously analyzed for flame retardants, phthalates, pesticides and per- and polyfluoroalkyl substances (PFAS). High-resolution mass spectrometry was used to support both targeted and suspect screening of dyes in dust. Statistical analyses were conducted to determine if dye concentrations were related to demographic information. Detection frequencies for 12 target dyes ranged from 11% to 89%; of the dyes that were detected in at least 50% of the samples, geometric mean levels ranged from 32.4 to 360 ng/g. Suspect screening analysis identified eight additional high-abundance azobenzene compounds in dust. Some dyes were correlated to numerous flame retardants and several antimicrobials, and statistically higher levels of some dyes were observed in homes of non-Hispanic Black mothers than in homes of non-Hispanic white mothers. To our knowledge, this is the most comprehensive study of azobenzene disperse dyes in house dust to date. Future studies are needed to quantify additional dyes in dust and to examine exposure pathways of dyes in indoor environments where children are concerned.

Gas-particle partitioning of organophosphate esters in indoor and outdoor air and its implications for individual exposure

The extensive utilization of organophosphate esters (OPEs) has resulted in their widespread presence in the environment, raising concerns about potential human health risks. In this study, 13 OPEs were analyzed in both gas and particle phases as well as in indoor and outdoor atmospheric environments. Moreover, human exposure to OPEs were investigated within a university environment, focusing on forehead contact and individual PM2.5 inhalation. The results showed similar distribution patterns of OPEs indoors and outdoors, although higher concentrations were found indoors. The average atmospheric concentration of ∑OPEs (combining particle and gaseous OPEs) was 1575 pg/m3 in the outdoor environment and 6574 pg/m3 ∑OPEs in the indoor microenvironments. The overwhelming majority of OPEs exhibit a pronounced propensity to adsorb onto PM2.5 particles. Notably, the concentration of OPEs on the forehead differed significantly from that in the atmospheric environment, whereas individual PM2.5 exposure was consistent with the concentration of indoor PM2.5. Intriguingly, some OPEs with high octanol-water partition coefficient (log Kow) were not detected in the environment but found on human foreheads. Gas-particle partitioning was predicted using the Harner-Bidleman and Li-Ma-Yang models and the results were in agreement with the monitoring data for approximately half of the OPE monomers. Correlations between OPEs exposure and gas-particle partitioning were found to be more significant for novel OPEs. No non-cancer risk to humans through individual exposure to OPEs was identified via forehead exposure or inhalation. The previously unreported relationship between individual exposure and the environmental occurrence of traditional and novel OPEs demonstrated in this study highlights the importance of evaluating the potential health risks associated with actual OPE exposure.

Review on typical organophosphate diesters (di-OPEs) requiring priority attention: Formation, occurrence, toxicological, and epidemiological studies

The impact of primary metabolites of organophosphate triesters (tri-OPEs), namely, organophosphate diesters (di-OPEs), on the ecology, environment, and humans cannot be ignored. While extensive studies have been conducted on tri-OPEs, research on the environmental occurrence, toxicity, and health risks of di-OPEs is still in the preliminary stage. Understanding the current research status of di-OPEs is crucial for directing future investigations on the production, distribution, and risks associated with environmental organophosphate esters (OPEs). This paper specifically reviews the metabolization process from tri-OPEs to di-OPEs and the occurrence of di-OPEs in environmental media and organisms, proposes typical di-OPEs in different media, and classifies their toxicological and epidemiological findings. Through a comprehensive analysis, six di-OPEs were identified as typical di-OPEs that require prioritized research. These include di-n-butyl phosphate (DNBP), bis(2-butoxyethyl) phosphate (BBOEP), bis(1,3-dichloro-2-propyl) phosphate (BDCIPP), bis(2-chloroethyl) phosphate (BCEP), bis(1-chloro-2-propyl) phosphate (BCIPP), and diphenyl phosphate (DPHP). This review provides new insights for subsequent toxicological studies on these typical di-OPEs, aiming to improve our understanding of their current status and provide guidance and ideas for research on the toxicity and health risks of di-OPEs. Ultimately, this review aims to enhance the risk warning system of environmental OPEs.

The environmental burden on endocrine neoplasia: a review on the documented impact of endocrine disrupting chemicals

INTRODUCTION

Endocrine-disrupting chemicals (EDCs) have gained more importance in the past decade, mostly due to their role in the pathogenesis of disease, especially in carcinogenesis. However, there is limited literature on the environmental burden on some of the less common endocrine neoplasia.

AREAS COVERED

This review focuses on both observational and experimental studies linking exposure to EDCs and endocrine neoplasia specifically pituitary, thyroid, adrenal and neuroendocrine tumors. Following PRISMA guidelines, a search of English peer-reviewed literature was performed using Medline and Google Scholar, giving preference to recent publications.

EXPERT OPINION

Exposure to EDC occurs not only in the household but also at work, whether it is in the office, factory, or farm and during transport from one location to another. Many studies have evaluated the effect of single environmental agents; however, humans are rarely exposed to only one EDC. Different EDCs and different levels of exposure may interact together to provide either a synergistic and/or an antagonistic disruption on human health, and hence a complex mechanism to elucidate. The ultimate adverse effect is difficult to predict, as it is not only influenced by the degree of exposure, but also by genetics, lifestyle, comorbidities, and other stressors.

Serum Organophosphate Flame retardants and plasticizers in Chinese females of childbearing age: Association with serum reproductive and thyroid hormones

Organophosphate flame retardants (OPFRs) are extensively used as flame retardants and plasticizers, but their endocrine disrupting potentials have raised concerns. However, the impacts of OPFR exposures on reproductive and thyroid hormones in females remains unclear. In this study, serum concentrations of OPFRs were investigated, and levels of reproductive and thyroid hormones, including follicle-stimulating hormone (FSH), luteinizing hormone (LH), estradiol, anti-Müllerian hormone, prolactin (PRL), testosterone (T), and thyroid stimulating hormone, were analyzed in childbearing-age females undergoing in-vitro fertilization treatment from Tianjin, a coastal city in China (n = 319). Tris (2-chloroethyl) phosphate (TCEP) was the predominant OPFR, with a median concentration of 0.33 ng/mL and a detection frequency of 96.6%. In the whole population, tris(1,3-dichloro-2-propyl) phosphate (TDCIPP) and tris(2-chloroisopropyl) phosphate (TCIPP) were positively associated with T (p < 0.05), while triethyl phosphate (TEP) was negatively associated with LH (p < 0.05) and LH/FSH (p < 0.01). Particularly, TCIPP was negatively associated with PRL in the younger subgroup (age≤30, p < 0.05). Moreover, TCIPP was negatively associated with diagnostic antral follicle counting (AFC) in the mediation analysis by a dominating direct effect (p < 0.01). In conclusion, serum levels of OPFRs were significantly associated with reproductive and thyroid hormone levels and a risk of decreased ovarian reserve in childbearing-age females, with age and body mass index being significant influencing factors.

Organophosphate Esters Disrupt Steroidogenesis in KGN Human Ovarian Granulosa Cells

Organophosphate esters (OPEs) are used extensively as flame retardants and plasticizers and are found ubiquitously in the environment and human matrices. Previous studies suggested that exposure to some of these chemicals may disrupt the homeostasis of female sex hormones and have detrimental effects on female fertility. Here, we determined the effects of OPEs on the function of KGN ovarian granulosa cells. We hypothesized that OPEs alter the steroidogenic ability of these cells by dysregulating the expression of transcripts involved in steroid and cholesterol biosynthesis. KGN cells were exposed for 48 hours to 1 of 5 OPEs (1-50μM): triphenyl phosphate (TPHP), tris(methylphenyl) phosphate (TMPP), isopropylated triphenyl phosphate (IPPP), tert-butylphenyl diphenyl phosphate (BPDP), and tributoxyethyl phosphate (TBOEP), or to a polybrominated diphenyl ether flame retardant, 2,2',4,4' tetrabromodiphenyl ether (BDE-47), in the presence or absence of Bu2cAMP. OPEs increased the basal production of progesterone (P4) and 17β-estradiol (E2) and had either no effect or inhibited Bu2cAMP-stimulated P4 and E2 synthesis; exposure to BDE-47 had no effect. Quantitative real-time polymerase chain reaction (qRT-PCR) analyses revealed that OPEs (≥5μM) increased the basal expression of critical genes (STAR, CYP11A1, CYP19A1, HSD3B2, and NR5A1) involved in steroidogenesis; upon stimulation, the expression of all genes tested was downregulated. An overall inhibition in cholesterol biosynthesis was induced by OPEs, characterized by a downregulation in HMGCR and SREBF2 expression. TBOEP consistently showed the least effect. Therefore, OPEs perturbed steroidogenesis in KGN granulosa cells by targeting the expression of steroidogenic enzymes and cholesterol transporters; these effects may have an adverse impact on female reproduction.

Electronic-waste-associated pollution of per- and polyfluoroalkyl substances: Environmental occurrence and human exposure

Occupational exposure to per- and polyfluoroalkyl substances (PFASs) is of serious concern because their adverse health effects. Nevertheless, knowledge regarding contamination in e-waste dismantling regions is rather scarce. We therefore analysed seven neutral PFASs (n-PFASs) and forty ionized PFASs (i-PFASs) in dust and hand wipes collected from an e-waste dismantling plant and homes. Both dust (1370 ng/g) and workers' hand wipe (1100 ng/m²) in e-waste dismantling workshops contained significantly higher median levels of ∑PFASs than those from homes (684 ng/g and 444 ng/m²) (p < 0.01). ∑PFAS concentrations in dust and on workers' hand wipes from workshops were significantly higher than those from storage area. 8:2 fluorotelomer alcohol was the dominant n-PFAS in workshop dust (70.7%) and on worker's hand wipes (46.6%). Perfluoroalkyl carboxylic acids (C2 -C3) were the significant components (based on concentration) of i-PFASs in dust (57.9%) and on hand wipes (89.6%). A significant positive correlation (p < 0.001) of ∑PFAS concentrations between workshop dust and workers' hand wipes was observed, indicating that they come from common sources. Compared to dust ingestion, hand-to-mouth contact was highlighted as a vital exposure route, accounting for 68.8% for workers and 72.2% for residential population, respectively, of the sum of two exposure doses.

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.

Occurrence and treatment effect assessment of organophosphorus flame retardants in source and drinking water, Jinan, China

The occurrence and removal efficiencies of organophosphorus flame retardants (OPFRs) by traditional treatment processes (pre-flocculation, sand filtration, and post-chlorination processes) and advanced treatment processes (i.e., ozone and granular activated carbon (GAC), ultraviolet/hydrogen peroxide (UV/H₂O₂), GAC alone, ultrafiltration membrane, nanofiltration membrane) were examined in two municipal plants and a pilot plant in Jinan, China. The concentrations of six OPFRs in raw waters were at levels of 16.8-100.0 ng/L, and three OPFRs were below the detection limits. The traditional treatment processes could not effectively remove the OPFRs (the removal efficiency was - 12.0-15.4%). The advanced oxidation with ozone and GAC (the removal efficiency was 35.6-60.3%) or UV/H₂O₂ and GAC processes (the removal efficiency was 68.0-86.7%) were more effective than the traditional water treatment processes. The removal efficiencies of ultrafiltration process for the OPFRs was 11.2-69.8% which were positively correlated with the logKow values of OPFRs. The nanofiltration membrane process with ultrafiltration membrane process as the pretreatment was the most effective process (the removal efficiencies were almost to 100%). These results imply that the combination of ultrafiltration membrane and nanofiltration membrane is an effective measure in the treatment of OPFRs in municipal drinking water plants.

High density polyethylene (HDPE) and thermoplastic polyurethane (TPU) wristbands as personal passive samplers monitoring per- and polyfluoroalkyl substances (PFASs) exposure to postgraduate students

Per- and polyfluoroalkyl substances (PFASs) present adverse effects for human health, which result in strong needs for reliable tools monitoring personal exposure to PFASs. This study manufactured two wristbands of high density polyethylene (HDPE) and thermoplastic polyurethane (TPU), and used the wristbands to monitor PFASs personal exposure. The analytical method was developed to measure 32 PFASs in the paired HDPE and TPU wristbands worn by 60 postgraduates. Twenty-nine of 32 PFASs were detected and hexafluoropropylene oxide dimer acid (HFPO-DA) was predominant individual PFASs with median concentrations of 337 and 554 pg/g for HDPE and TPU wristbands respectively. The gender and grade of students had moderate effects on PFASs distribution in the wristbands. Higher PFASs levels were determined in the two wristbands worn by the male students compared to the females, and the greatest PFASs concentration was observed in the wristbands worn by the first-year postgraduates, follow by second- and third-year postgraduates. Additionally, significant correlations between paired HDPE and TPU wristbands were observed for perfluorobutanoic acid (PFBA), perfluorohexane sulfonic acid (PFHxS), perfluoroheptane sulfonic acid (PFHpS), perfluorooctane sulfonic acid (PFOS), and HFPO-DA. These results suggest that HDPE and TPU wristbands can be used as effective tools for monitoring personal PFAS exposure.

Handwipes as indicators to assess organophosphate flame retardants exposure and thyroid hormone effects in e-waste dismantlers

Dermal exposure is increasingly recognized as an important pathway for organic pollutant exposure. However, data on dermal exposure are limited, particularly with respect to the health effects. This study evaluated association between organophosphorus flame retardants (OPFRs) in handwipes and internal body burden on workers and adult residents in an electronic waste (e-waste) dismantling area. The impact of dermal exposure to OPFRs on thyroid hormones (THs) served as a biomarker for early effects. Triphenyl phosphate (TPhP) was the most detected compound in handwipes, with median levels of 1180, 200, and 24.0 ng in people identified as e-waste bakers, e-waste dismantlers, and adult residents. Among e-waste dismantlers, TPhP levels in handwipes were positively correlated with paired serum TPhP and urinary diphenyl phosphate (DPhP) levels. In multiple linear regression models controlling for sex, age and smoking, TPhP levels in handwipes of e-waste dismantlers were significantly negatively correlated with three THs used to evaluate thyroid function: serum reverse 3,3',5-triiodo-L-thyronine (rT3), 3,3'-diiodo-L-thyronine (3,3'-T2), and 3,5-diiodo-L-thyronine (3,5-T2). These findings suggest that handwipes can act as non-invasive exposure indicators to assess body burden of dermal exposure to TPhP and health effects on THs of e-waste dismantlers. This study highlights importance of OPFR effect on human THs through dermal exposure.

Developmental exposure to the flame retardant, triphenyl phosphate, causes long-lasting neurobehavioral and neurochemical dysfunction

BACKGROUND

Human exposures to organophosphate flame retardants result from their use as additives in numerous consumer products. These agents are replacements for brominated flame retardants but have not yet faced similar scrutiny for developmental neurotoxicity. We examined a representative organophosphate flame retardant, triphenyl phosphate (TPP) and its potential effects on behavioral development and dopaminergic function.

METHODS

Female Sprague-Dawley rats were given low doses of TPP (16 or 32 mg kg^-1  day^-1 ) via subcutaneous osmotic minipumps, begun preconception and continued into the early postnatal period. Offspring were administered a battery of behavioral tests from adolescence into adulthood, and littermates were used to evaluate dopaminergic synaptic function.

RESULTS

Offspring with TPP exposures showed increased latency to begin eating in the novelty-suppressed feeding test, impaired object recognition memory, impaired choice accuracy in the visual signal detection test, and sex-selective effects on locomotor activity in adolescence (males) but not adulthood. Male, but not female, offspring showed marked increases in dopamine utilization in the striatum, evidenced by an increase in the ratio of the primary dopamine metabolite (3,4-dihydroxyphenylacetic acid) relative to dopamine levels.

CONCLUSIONS

These results indicate that TPP has adverse effects that are similar in some respects to those of organophosphate pesticides, which were restricted because of their developmental neurotoxicity.

Associations of gestational exposure to organophosphate esters with gestational age and neonatal anthropometric measures: The HOME study

Organophosphate esters (OPEs) are developmental toxicants in experimental studies of animals, but limited evidence is available in humans. We included 340 mother-infant pairs in the Health Outcomes and Measures of the Environment (HOME) Study (Cincinnati, Ohio, USA) for the analysis. We evaluated gestational exposure to OPEs with gestation age at birth and newborn anthropometric measures. We quantified four OPE urinary metabolites at 16 weeks and 26 weeks of gestation. We extracted gestational age at birth, newborn weight, length, and head circumference from the chart review. We calculated z-scores for these anthropometric measures and the ponderal index. We used multiple informant models to examine the associations between repeated OPE measurements and the outcomes. We used modified Poisson regression to estimate the association of gestational exposure to OPEs with preterm birth. We also explored effect modification by infant sex and the potential mediation effect by the highest maternal blood pressure and glucose levels. We found that bis(2-chloroethyl) phosphate (BCEP) at 16 weeks and diphenyl phosphate at 26 weeks of pregnancy were positively associated with gestational age and inversely associated with preterm birth. In female newborns, BCEP at 16 weeks was inversely related to birth weight and length z-scores. In male newborns, we observed negative associations of 26-week di-n-butyl phosphate with the ponderal index at birth. No mediation by the highest maternal blood pressure or glucose levels during pregnancy was identified. In this cohort, gestational exposure to some OPEs was associated with gestational age, preterm birth, and neonatal anthropometric measures. Certain associations tended to be window- and infant sex-specific.

Reproductive and developmental toxicity following exposure to organophosphate ester flame retardants and plasticizers, triphenyl phosphate and isopropylated phenyl phosphate, in Sprague Dawley rats

Two organophosphate esters used as flame retardants and plasticizers, triphenyl phosphate (TPHP) and isopropylated phenyl phosphate (IPP), have been detected in environmental samples around the world. Human exposure primarily occurs via oral ingestion with reported higher concentrations in children. Currently, there are no data to evaluate potential risk from exposure to either TPHP or IPP during fetal development. These short-term perinatal studies in rats provide preliminary toxicity data for TPHP and IPP, including information on transfer to fetus/offspring and across the pup blood-brain barrier. In separate experiments, TPHP or IPP were administered via dosed feed at concentrations 0, 1000, 3000, 10 000, 15 000, or 30 000 ppm to time-mated Hsd:Sprague Dawley SD rats from gestation day (GD) 6 through postnatal day (PND) 28; offspring were provided dosed feed at the same concentration as their dam (PND 28-PND 56). TPHP- and IPP-related toxicity resulted in removal of both 30 000 ppm groups on GD 12 and 15 000 ppm IPP group after parturition. Body weight and organ weights were impacted with exposure in remaining dams. Reproductive performance was perturbed at ≥10 000 ppm TPHP and all IPP exposure groups. In offspring, both TPHP- and IPP-related toxicity was noted in pups at ≥10 000 ppm as well as reduction in bodyweights, delays in pubertal endpoints, and/or reduced cholinesterase enzyme activity starting at 1000 ppm TPHP or IPP. Preliminary internal dose assessment indicated gestational and lactational transfer following exposure to TPHP or IPP. These findings demonstrate that offspring development is sensitive to 1000 ppm TPHP or IPP exposure.

Silicone wristband- and handwipe-based assessment of exposure to flame retardants for informal electronic-waste and end-of-life-vehicle recycling workers and their children in Vietnam

Measuring personal exposure to flame retardants (FRs) is crucial for assessing and controlling human health risks posed by FRs during the recycling of electronic waste (e-waste) and end-of-life vehicles (ELVs). Here, we examined the use of handwipes and silicone wristbands to measure personal FR exposure for e-waste and ELV recycling workers and their children in Vietnam. On the handwipes from the e-waste recycling workers, the predominant five FRs detected were TBBPA (median concentration: 3700 ng/wipe), BDE-209 (1700 ng/wipe), TPHP (500 ng/wipe), DBDPE (410 ng/wipe), and BPA-BDPP (360 ng/wipe). On the handwipes from ELV recycling workers, TPHP (60 ng/wipe), IPPDPP (47 ng/wipe), BIPPPP/DIPPDPP (33 ng/wipe), BDE-209 (26 ng/wipe), and TCIPP (23 ng/wipe) were detected as the five predominant FRs. On the wristbands from the e-waste recycling workers, the five predominant FRs detected were TBBPA (median concentration: 340 ng/g), BDE-209 (330 ng/g), DBDPE (65 ng/g), TPHP (50 ng/g), and TMPP (34 ng/g). On the wristbands from the ELV recycling workers, TPHP (34 ng/g), IPPDPP (18 ng/g), TCIPP (14 ng/g), TDMPP (13 ng/g), BIPPPP/DIPPDPP (9.3 ng/g) and TMPP (9.3 ng/g) were detected as the predominant FRs. The data obtained with the wristbands were comparable to those obtained with the handwipes. Similar FR profiles were found in between the workers and their children. The profiles indicate that the informal e-waste and ELV recycling caused FR exposure not only for workers but also for their children who live in the workshops. By using the handwipe and wristband sampling approaches, we determined types and concentrations of FRs to which the workers and their children were dominantly exposed. Silicone wristband- and handwipe-based assessment is expected to be effective means of measuring personal FR exposure for the informal e-waste and ELV recycling workers and their children.

Widespread formation of toxic nitrated bisphenols indoors by heterogeneous reactions with HONO

With numerous structurally diverse indoor contaminants, indoor transformation chemistry has been largely unexplored. Here, by integrating protein affinity purification and nontargeted mass spectrometry analysis (PUCA), we identified a substantial class of previously unrecognized indoor transformation products formed through gas-surface reactions with nitrous acid (HONO). Through the PUCA, we identified a noncommercial compound, nitrated bisphenol A (BPA), from house dust extracts strongly binding to estrogen-related receptor γ. The compound was detected in 28 of 31 house dust samples with comparable concentrations (ND to 0.30 μg/g) to BPA. Via exposing gaseous HONO to surface-bound BPA, we demonstrated it likely forms via a heterogeneous indoor chemical transformation that is highly selective toward bisphenols with electron-rich aromatic rings. We used 15N-nitrite for in situ labeling and found 110 nitration products formed from indoor contaminants with distinct aromatic moieties. This study demonstrates a previously unidentified class of chemical reactions involving indoor HONO, which should be incorporated into the risk evaluation of indoor contaminants, particularly bisphenols.

Distribution of flame retardants among indoor dust, airborne particles and vapour phase from Beijing: spatial-temporal variation and human exposure characteristics

The occurrence and distribution of 10 brominated flame retardants (BFRs) and 10 organophosphate flame retardants (OPFRs) were investigated in indoor dust, total suspended particles (TSP), and vapour phase from offices (n = 10), homes (n = 9), and day-care centres (n = 10) in Beijing, China. Three types of samples were collected biweekly from one office and one home over a year to examine temporal trends. BFRs in dust significantly correlated with those in TSP, while OPFRs significantly correlated among all three matrices. In addition, BFRs in dust (ng/g) and TSP (pg/m³) exhibited similar temporal trends with higher levels in the cold season, whereas OPFRs in TSP and vapour phase (pg/m³) showed similar temporal trends with higher levels in the warm season. The geometric mean concentrations of BFRs and OPFRs in the three matrices from the above mentioned three types of indoor microenvironments were used for exposure and health risk estimation, and ∑₇OPFRs showed much higher hazard index (HI) values than ∑₁₀BFRs for all subpopulations, and inhalation of OPFRs was a major risk source. With the volatility of flame retardants (FRs) decreasing, the contribution of dust ingestion and dermal absorption showed an increasing trend, and the contribution of inhalation exhibited a gradual decreasing trend, which implied the dominant exposure pathway to FRs is strongly related to the vapour pressure (25 °C, Pa) of these substances. Using a single type of microenvironment or the collection of samples at a single point in time can lead to overestimation or underestimation of overall exposure and risk for people to some extent. The correlations of FRs in dust, TSP, and vapour phase from indoor microenvironments, as well as their temporal trends were first reported in this study, which will provide a basis for more accurate FR exposure assessments in the future.

An overview of organophosphate esters and their metabolites in humans: Analytical methods, occurrence, and biomonitoring

With the strict regulation of brominated flame retardants, organophosphate esters (OPEs) have been extensively used as replacements. Increasing concerns on OPEs have aroused due to their extensive distribution in the environment and humans, as well as their potential toxicities. Recent studies have demonstrated that some organophosphate di-esters are even more toxic than their respective tri-esters. This review summarized the current state of knowledge on the analytical methodologies (including sample collection and preparation, instrumental analysis, and the feasibility of each potential human matrix), as well as the occurrences of OPEs and/or their metabolites (m-OPEs) in various human matrices. Organophosphate esters are readily metabolized in human thus only limited studies reported their occurrences in blood and breast milk, whereas abundant studies are available regarding the occurrences of m-OPEs rather than OPEs in urine. Since none of the matrix is suitable all the time, appropriate matrix should be selected depending on the aims of biomonitoring studies, e.g., high throughput screening or body burden estimation. Biomonitoring with non-invasive matrices such as hair and/or nail is useful to screen specific populations that might be under high exposure risks while urine is more suitable to provide valuable information on body burden. In terms of urinary monitoring, specific biomarkers have been identified for some OPE compounds, including tri(2-butoxyethyl) phosphate, tri(1,3-dichloro-2-propyl) phosphate, tri(2-chloroethyl) phosphate and tri(1-chloro-2-propyl) phosphate. Further studies are required to identify suitable urinary biomarkers for other OPE compounds, especially the emerging ones.

Silicone wristbands as personal passive sampling devices: Current knowledge, recommendations for use, and future directions

Personal chemical exposure assessment is necessary to determine the frequency and magnitude of individual chemical exposures, especially since chemicals present in everyday environments may lead to adverse health outcomes. In the last decade, silicone wristbands have emerged as a new chemical exposure assessment tool and have since been utilized for assessing personal exposure to a wide range of chemicals in a variety of populations. Silicone wristbands can be powerful tools for quantifying personal exposure to chemical mixtures in a single sample, associating exposure with health outcomes, and potentially overcoming some of the challenges associated with quantifying the chemical exposome. However, as their popularity grows, it is crucial that they are used in the appropriate context and within the limits of the technology. This review serves as a guide for researchers interested in utilizing silicone wristbands as a personal exposure assessment tool. Along with briefly discussing the passive sampling theory behind silicone wristbands, this review performs an in-depth comparison of wristbands to other common exposure assessment tools, including biomarkers of exposure measured in biospecimens, and evaluates their utility in exposure assessments and epidemiological studies. Finally, this review includes recommendations for utilizing silicone wristbands to evaluate personal chemical exposure and provides suggestions on what research is needed to recognize silicone wristbands as a premier chemical exposure assessment tool.

Ubiquitin proteasomal system is a potential target of the toxic effects of organophosphorus flame retardant triphenyl phosphate

The consumption of the widely used flame retardant Triphenyl phosphate (TPP) is increasing. It is now frequently detected in the environment and also domestically. Although the possibility of dermal exposure to TPP is quite high, little is known about its potential molecular toxicity mechanisms. In this study, we found that TPP caused cytotoxicity on human skin keratinocytes (HaCaT) and significantly inhibited the proliferation and cell migration in a concentration-dependent manner. Additionally, HaCaT cells were sensitive to TPP-induced apoptosis. Reactive oxygen species production was induced with TPP, which increased the protein carbonylation and lipid peroxidation levels. Moreover, TPP inhibited proteasome activity and increased the accumulation of ubiquitinated proteins. Exposure to TPP significantly increased the HSP90, HSP70, GRP94 and GRP78 protein levels. Overall, our findings indicate that TPP may pose a risk to human health and contribute to the current understanding of the risks of TPP at the molecular level.

Pre- and post-natal exposure of children to organophosphate flame retardants: A nationwide survey in France

The use of organophosphate flame retardants (OPFRs) has been on the rise ever since many brominated flame retardants were banned, back in the 2000 s. The objectives of this study are to describe the pre- and post-natal exposure of children to OPFRs, and to explore their possible determinants. A total of 259 children aged 3.5 years and 388 mothers from the French ELFE mother-child cohort were included. Both pre- and post-natal exposure to OPFRs were assessed, using OPFR concentrations in the hair of pregnant women (in 2011) and their 3.5-year-old children (in 2014-2015) for 15 OPFRs, of which 9 were detected in > 20 % hair samples. The highest geometric means for pre-natal exposure were 272 ng/g for tris(1-chloro-2-propyl) phosphate (TCPP), 69.7 ng/g for ng/g for triphenyl phosphate (TPP) and 54.4 ng/g for tris(1,3-dichloro-2-propyl) phosphate (TDCPP). The highest geometric means for post-natal exposure were 249.6 ng/g for TCPP, 85.3 ng/g for TDCPP and 83.8 ng/g for 2-ethylhexyl diphenyl phosphate (EHDPP). Correlations were found between both pre-natal exposures, and between pre-and post-natal exposures. No correlation was however found between pre-and post-natal exposures for any given OPFR. Pre-natal exposure to the 9 OPFRs was associated with pre-natal exposure to polybrominated diphenyl ethers 209 (BDE209), and 47 (BDE47). Maternal BMI was associated with pre-natal exposure to OPFRs other than TBEP. Home renovation work prior to birth was also associated with pre-natal exposure to OPFRs, with the exception of EHDPP, tris(2-butoxyethyl) phosphate (TBEP) and triethyl phosphate (TEP). Determinants of post-natal exposure appeared more disparate across OPFRs; although both the type of flooring in children's rooms and pre-natal exposure to polybrominated diphenyl ethers seem to be associated with post-natal exposure. Lastly, higher socioeconomic status appeared to be associated with lower exposure for several (though not all) OPFRs. The high prevalence of exposure to OPFRs suggests the need for studies to assess the health effects of OPFRs exposure, particularly on children.

Occupational exposure to rare earth elements: Assessment of external and internal exposure

Our study investigated occupational exposure to rare earth elements (REEs) in a major REE processing plant from North China by assessing both external exposure and internal exposure in the workers. An exposure group, including 50 workers in the processing plant, and a control group, including 50 workers from a liquor factory located 150 km away from the exposure group, were recruited in the study. Portable air sampler was employed to accurately measure individual exposure to the external environment, and the data demonstrating significantly higher contamination in the REE processing plant compared with the control group (i.e., 87.5 versus 0.49 μg/m³ of ΣREEs). Blood concentrations were also significantly higher in the exposure group (3.47 versus 2.24 μg/L of ΣREEs). However, the compositional profiles of REEs resembled between the exposure and control group in blood or air particles, indicating the influence of mining/processing activities on the surrounding regions. External exposure in the occupational environment appeared to significantly influence internal REE exposure in the REE processing workers. Some other sociodemographic and occupational factors, including the residence time and the type of work, could also influence occupational exposure to selected REEs. Our data clearly demonstrated the highly elevated REE contamination in both working environment and human bodies compared with the control subjects, raising the critical need for better assessing the health risks from occupational REE exposure and efficient management for occupational hazards.

Emerging Plasticizers in South China House Dust and Hand Wipes: Calling for Potential Concern?

Following regulations on legacy plasticizers, a large variety of industrial chemicals have been employed as substitutes to manufacture consumer products. However, knowledge remains limited on their environmental distributions, fate, and human exposure risks. In the present work, we screened for a total of 34 emerging plasticizers in house dust from South China and matched hand wipes collected from volunteers (n = 49 pairs). The results revealed a frequent detection of 27 emerging plasticizers in house dust, with the total concentrations reaching a median level of 106 700 ng/g. Thirteen of them had never been investigated by any environmental studies prior to our work, which included glycerol monooleate (median: 61 600 ng/g), methyl oleate (16 400 ng/g), butyl oleate (411 ng/g), 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate (341 ng/g), 2,2,4-trimethyl-1,3-pentanediol diisobutyrate (105 ng/g), isopropyl myristate (154 ng/g), di(2-ethylhexyl) sebacate (69.1 ng/g), triisononyl trimellitate (64.4 ng/g), as well as a few others. Emerging plasticizers were also frequently detected in hand wipes, with a median total level of 4680 ng, indicating potential exposure via hand-to-mouth contact. Several chemicals, including acetyl tributyl citrate, tributyl citrate, di-n-butyl maleate, isopropyl myristate, and isopropyl palmitate, exhibited significant correlations between dust and hand wipe. However, other plasticizers did not follow this pattern, and the chemical compositional profiles differed between dust and hand wipe, suggesting chemical-specific sources and exposure pathways. Although the estimation of daily intake (EDI) indicated no substantial risks through dust ingestion or hand-to-mouth transfer of emerging plasticizers, continuous monitoring is needed to explore whether some of the important plasticizers are safe replacements or regrettable substitutions of the legacy ones.

Infants' diminished response to DTaP vaccine is associated with exposure to organophosphate esters

Organophosphate esters (OPEs) are commonly applied as flame retardants and plasticizers. Toxicological studies suggest exposure effects on immune endpoints, raising concerns as infants' OPE exposures are elevated compared to older children and adults due to hand-to-mouth behavior and breastfeeding. Here, we sought to evaluate the immune responsiveness of infants to a neoantigen (e.g., a newly encountered antigen) in the presence of OPE exposures. As a proxy for immune responsiveness, children were given three doses of the Diphtheria, Tetanus, and Pertussis (DTaP) vaccine as recommended, and diphtheria and tetanus antibodies were evaluated in serum samples collected when children were 12 months old (n = 84). Titers were compared, based on maximum sample overlap, to measurements of OPE metabolites in spot urine samples collected before vaccination (age 2 months, n = 73) and at the time of antibody assessment (12 months of age, n = 46). Metabolites of two chlorinated OPEs were significantly associated with diminished antibodies for diphtheria and tetanus. A metabolite of tris (1,3-dichloroisopropyl)phosphate (TDCIPP) measured at 2 months was associated with decreased diphtheria antibodies (-0.07 IU/mL per log₁₀ increase in metabolite). One metabolite of tris(2-chloroisopropyl)phosphate (TCIPP) measured at 12 months was associated with decreased tetanus antibodies (-0.57 IU/mL per log₁₀ increase in metabolite). These results provide some preliminary insights for OPE exposure impacts on vaccine responses in early life and may have important implications for immune health through childhood and adulthood.

Variability and predictors of urinary organophosphate ester concentrations among school-aged children

Organophosphate esters (OPE) are flame retardants and plasticizers used in a wide range of consumer products. Despite their widespread use, few studies have characterized pediatric exposures. We assessed variability and predictors of OPE exposures in a cohort panel study of 179 predominantly Black school-aged children with asthma in Baltimore City, MD. The study design included up to four seasonal week-long in-home study visits with urine sample collection on days 4 and 7 of each visit (nsamples = 618). We quantified concentrations of 9 urinary OPE biomarkers: bis(2-chloroethyl) phosphate (BCEtp), bis(1-chloro-2-propyl) phosphate, bis(1,3-dichloro-2-propyl) phosphate (BDCPP), di-benzyl phosphate (DBuP), di-benzyl phosphate, di-o-cresylphosphate, di-p-cresylphosphate (DPCP), di-(2-propylheptyl) phthalate (DPHP), 2,3,4,5-tetrabromo benzoic acid. We assessed potential predictors of exposure, including demographic factors, household characteristics, and cleaning behaviors. We calculated Spearman/tetrachoric correlations and intraclass correlation coefficients (ICCs) to examine within-week and seasonal intra-individual variability, respectively. We assessed OPE predictors using linear models for continuous log2 concentrations (BDCPP and DPHP) and logistic models for odds of detection (BCEtP, DBuP, DPCP), with generalized estimating equations to account for repeated measures. For all OPEs, we observed moderate within-week correlations (rs: 0.31-0.63) and weak to moderate seasonal reliability (ICC: 0.18-0.38). BDCPP and DPHP concentrations were higher in the summer compared to other seasons. DPHP concentrations were lower among males than females (%diff: -53.5%; 95% CI: -62.7, -42.0) and among participants spending >12 h/day indoors compared to ≤12 h (%diff: -20.7%; 95% CI: -32.2, -7.3). BDCPP concentrations were lower among children aged 8-10 years compared to 5-7 years (%diff: -39.1%; 95% CI: -55.9, -15.9) and higher among children riding in a vehicle on the day of sample collection compared to those who had not (%diff: 28.5%; 95% CI: 3.4, 59.8). This study is the first to characterize within-week and seasonal variability and identify predictors of OPE biomarkers among Black school-aged children, a historically understudied population.

Indoor exposure to selected flame retardants and quantifying importance of environmental, human behavioral and physiological parameters

Indoor exposure to organic flame retardants (FRs) has raised extensive concern due to associated adverse health effects. Indoor-exposure induced daily intakes of six widely used FRs individually ranged 0.002-611 ng/day and 0.02-463 ng/day, respectively, for adults and 2-6-year-old children; and resulting internal exposure levels ranged 0.1-159 and 2.1-4500 ng/g lipid, respectively. A proportion of 0.001-5.9% and 0.006-10.3% of individual FRs emitted into indoor air ultimately entered bodies of adults and children respectively. Tris(2-chloroisopropyl)phosphate dominated in emissions, whilst 2-ethylhexyl-2,3,4,5-tetrabromobenzoate dominated in human bodies. Hand-to-mouth contact was the most important exposure pathway for less volatile FRs including most brominated FRs, whilst inhalation was the predominant intake pathway of tris(2-chloroisopropyl)phosphate. Relative importance of 29 environmental, behavioral and physiological parameters was ranked to explore key drivers influencing exposure and accumulation of FRs in humans. Results suggested that frequent bathing and handwashing can reduce exposure effectively, especially for children. Bodyweight and lipid fraction were only positively related to internal accumulation and body-weight-normalized concentrations of compounds with low metabolic rates (half-lives ≥10³ h) in humans. Our findings help control indoor exposure to FRs and are supportive of human exposome studies in the future.

Maternal urinary organophosphate ester metabolite concentrations and glucose tolerance during pregnancy: The HOME Study

BACKGROUND

Endocrine-disrupting chemicals may alter glucose homeostasis, especially during pregnancy. Biomonitoring studies suggest ubiquitous human exposure to organophosphate esters (OPEs), chemicals with endocrine-disrupting capabilities. Few studies have examined the association between maternal exposure to OPEs and blood glucose during pregnancy.

METHODS

With data from 301 pregnant women in the Health Outcomes and Measures of the Environment (HOME) Study, a prospective pregnancy and birth cohort in Cincinnati, Ohio, USA, we examined whether OPE concentrations were associated with changes in blood glucose. We quantified four OPE metabolites in maternal spot urine samples collected at 16- and 26-weeks pregnancy. We extracted results from the glucose challenge test (GCT) and oral glucose tolerance test (OGTT) via medical chart review. Women with GCT ≥ 140 mg/dL or any abnormal values in OGTT (≥ 95 mg/dL fasting glucose, ≥ 180 mg/dL 1-h glucose, ≥ 155 mg/dL 2-h glucose, ≥ 140 mg/dL 3-h glucose) were defined as having elevated glucose levels. We used linear regression and Bayesian Kernel Machine Regression (BKMR) to estimate the associations of individual OPE metabolites and OPE mixtures with blood glucose levels during pregnancy. We used modified Poisson regression to estimate the associations of OPE metabolite concentrations with elevated glucose levels. We further examined effect measure modification by maternal characteristics (age, pre-pregnancy body mass index [BMI], and race/ethnicity).

RESULTS

Diphenyl phosphate (DPHP) had the highest geometric mean concentration of the urinary OPE metabolites (1.83 μg/L at 16 weeks, 1.24 μg/L at 26 weeks). Thirty women (10.0%) had elevated glucose levels. Individual OPE metabolites or their mixtures were not significantly associated with continuous GCT results. We did not observe effect measure modification by maternal age, pre-pregnancy BMI categories, or race/ethnicity. Compared with women in the 1st tertile of average DPHP of 16- and 26 weeks of pregnancy, women in the 3rd tertile tended to have a reduced risk of elevated glucose levels (RR = 0.41, 95% CI = 0.16-1.06, p for trend = 0.06).

CONCLUSION

In this cohort, maternal urinary OPE metabolite concentrations were weakly associated with blood glucose levels during pregnancy.

Remodeling on adipocytic physiology of organophosphorus esters in mature adipocytes

The emerging endocrine disruption chemicals organophosphate esters (OPEs) pose high risk of metabolic disruption. However, limited information is available on physiological disturbance of OPEs on adipose, a major endocrine and metabolic organ. In this study, physiological change was investigated after exposing 3T3-L1fully differentiated adipocytes to six OPEs at non-cytotoxic concentrations. We found two chlorinated-OPEs (tris-(2-chloro-1-(chloromethyl) ethyl) phosphate (TDCPP) and tris(2-chloroisopropyl) phosphate (TCPP)) and two alkyl-OPEs (tributyl phosphate (TBP) and tris (2-butoxyethyl) phosphate (TBEP)) induced inflammation-like adipokines (chemoattractant protein 1 and interleukin-6), respectively. Increment of insulin-resistance-related hormones (resistin and leptin) were observed under TDCPP, TCPP, and TBP exposure. Functional and mechanistic investigation revealed that all of the compounds inhibited lipolysis at basal level through dephosphorylated HSL^ser563, the rate limiting enzyme of lipolysis. Triphenyl phosphate (TPhP), tricresyl phosphate (TCP), TDCPP, TBP and TBEP enhanced glucose uptake at both basal and insulin-stimulated status. We evidenced that impact was independent of the classical pIRS^ser639/pAKT^ser473 nor the insulin-independent AMPK pathway. The elevated mRNA of slc2a4 and its transcriptional factor LXRα may, at least partially, explain for the increase of glucose uptake. Given the focus within the endocrine disruption on glands, it would be prudent not to ignore endocrinal impact on adipocytes.

Occupational exposure to organophosphate esters in e-waste dismantling workers: Risk assessment and influencing factors screening

Organophosphate esters (OPEs) are increasingly added in electronic products as alternative flame retardants, which may result in high occupational exposure of electronic waste recycling employees. This study investigated occupational exposure to OPEs in an e-waste recycling site in northern China, with intent to explore the impacts of occupational exposure and dismantling manipulation mode. Human urine samples from three sites with different distances from the core dismantling area, including employees from family workshops and plants with centralized management and residents from nearby areas, were collected and analyzed for OPEs' metabolites (mOPEs). The urinary ∑mOPEs' median concentrations (0.910 ng/mL) of all employees were significantly higher than those of residents in Ziya Town (0.526 ng/mL) and Jinghai downtown (0.600 ng/mL), suggesting the risk of occupational OPEs' exposure associated with e-waste dismantling. However, the spatial variation was insignificant for residents with different distances from the e-waste recycling site. Besides, OPEs' exposure levels were significantly affected by manipulation modes and the urinary ∑mOPEs' median concentrations in the employees of family workshops (1.05 ng/mL) were significantly higher than those in plants with centralized management (0.667 ng/mL). The result suggests that mechanical dismantling and active ventilating measures can reduce the OPEs' occupational exposure risk. Moreover, ∑mOPEs were higher in volunteers with age above 50 years old and in the underweight subgroup. Finally, different categories of mOPEs in human urine showed associations with corresponding OPEs in dust samples in the same area.

Development of magnetic molecularly imprinted solid-phase extraction and ultra-high performance liquid chromatography tandem mass spectrometry for rapid and selective determination of urinary diphenyl phosphate of college students

Organophosphate esters (OPEs), known as novel alternative flame retardants, are a class of environmental endocrine disruptors. Long-term exposure to OPEs may bring a non-negligible health risk to human. Urinary OPE metabolites (mOPEs) are generally used as biomarkers to evaluate the internal exposure to OPEs. Diphenyl phosphate (DPHP), the main metabolite of aryl-OPEs, exhibited high detection rates and concentrations in urine samples. To establish a selective and simple analytical method for biomonitoring urinary DPHP, a specific magnetic molecular imprinted polymer (MMIP) was fabricated via a sol-gel method. Under optimum magnetic solid-phase extraction (MSPE) conditions, the resultant MMIP exhibited selective recognition ability, ideal adsorption capacity and good reusability on urinary DPHP enrichment. The developed MSPE method coupled with ultra-high performance liquid chromatography tandem mass spectrometry (U-HPLC-MS/MS) exhibited good precision and accuracy (spiked recoveries of 85.8%-109% with relative standard deviations (RSDs) ranged from 5.1%-13%), low detection limit of 0.035 ng/mL, and negligible matrix inhibition. Then we used this proposed method to detect urinary DPHP levels of recruited 30 college students and investigate the time variability and potential determinants. All urine samples revealed the presence of DPHP at a median concentration of 0.56 μg/g Creatinine (Cr). Moderate reproducibility of DPHP level was observed in first morning urine samples (ICC>0.40). Significant correlations were found between urinary DPHP levels and gender (β=0.72; 95% CI: 0.48∼0.96), sampling time (β=0.36; 95% CI: 0.08∼0.65) as well as the frequency for take-out food (β=0.45; 95% CI: 0.07∼0.74) (p< 0.05). Hence, a fast and sensitive MSPE-U-HPLC-MS/MS method was successfully built to quantify urinary DPHP.

E-waste dismantling-related occupational and routine exposure to melamine and its derivatives: Estimating exposure via dust ingestion and hand-to-mouth contact

Melamine (MEL) and its derivatives are increasingly applied as nitrogenous flame retardants in consumer products. Nevertheless, limited information is available on their environmental occurrence and subsequent human exposure via multiple exposure pathways. In this study, we analysed MEL and its derivatives in dust (indication of the dust ingestion route) and hand wipe samples (indication of the hand-to-mouth route) collected in various microenvironments. The levels of ∑MELs in both dust (median: 24,100 ng/g) and participant hand samples (803 ng/m²) collected in e-waste dismantling workshops were significantly higher than those in samples collected in homes (15,600 ng/g and 196 ng/m², respectively), dormitories (13,100 ng/g and 227 ng/m², respectively) and hotel rooms (11,800 ng/g and 154 ng/m², respectively). Generally, MEL dominated in dust samples collected in e-waste dismantling workshops, whereas cyanuric acid dominated in hand wipe samples. This may occur partly because the latter is an ingredient in disinfection products, which are more frequently employed in daily lives during the COVID-19 pandemic. Exposure assessment suggests that dust ingestion is an important exposure pathway among dismantling workers and the general population, whereas hand-to-mouth contact could not be overlooked in certain populations, such as children and dismantling workers not wear gloves at work.

Organophosphate esters in children and adolescents in Liuzhou city, China: concentrations, exposure assessment, and predictors

Dermal contact with dust is commonly considered an important pathway of exposure to organophosphate esters (OPEs), but the importance of OPE uptake from diet is unclear. Herein, we used hand wipes to estimate OPE exposure from indoor dust and examined whether urinary OPE metabolite concentrations were influenced by sociodemographic characteristics, OPE amount in hand wipes, and dietary factors. OPEs were measured in urine and hand wipes from 6 to 18-year-old children and adolescents (n=929) in Liuzhou, China. Sociodemographic and dietary factors were obtained from questionnaire. Six OPE metabolites were detected in >70% of the urine samples, and seven OPEs were detected in >50% of the hand wipes. Estimated daily intakes (EDIs) were calculated using urinary OPE metabolites to investigate the total daily intake of OPEs, in which 0.36-10.1% of the total intake was attributed to the exposure from dermal absorption. In multivariate linear regression models, sex, age, and maternal education were significant predictors of urinary OPE metabolite concentrations. Urinary diphenyl phosphate (DPHP) is positively associated with its parent compounds 2-ethylhexyl-diphenyl phosphate (EHDPP) and triphenyl phosphate (TPHP) in hand wipes. High versus low vegetable intake was associated with a 23.7% higher DPHP (95% confidence interval (CI): 0.51%, 52.1%). Barreled water drinking was associated with a 30.4% (95% CI: 11.8%, 52.0%) increase in bis(1-chloro-2-propyl) 1-hydroxy-2-propyl phosphate (BCIPHIPP) compared to tap water drinking. Our results suggested the widespread exposure to OPEs in children and adolescents. In addition to dermal absorption, dietary intake may be an important exposure source of certain OPEs.

Dermal uptake of chlorinated organophosphate flame retardants via contact with furniture fabrics; implications for human exposure

The chlorinated organophosphate flame retardants (Cl-PFRs): tris-(2-chloroethyl)-phosphate (TCEP), tris-(1-chloro-2-propyl)-phosphate (TCIPP) and tris-(1,3-dichloropropyl)-phosphate (TDCIPP), have been widely used in upholstered furniture despite their carcinogenic potential. Although Cl-PFRs are mainly added to furniture foam, they are present in the fabrics likely due to migration from the foam. While several studies have assessed human exposure to Cl-PFRs via different pathways, no information exists on dermal uptake of these chemicals through contact with fabrics. In the current study, dermal absorption of TCEP, TCIPP and TDCIPP from 3 UK domestic furniture fabrics was experimentally assessed for the first time using in vitro 3D-human skin equivalents (EpiSkin™) under different real-life exposure scenarios. Results revealed all 3 target Cl-PFRs were dermally bioavailable to varying degrees (3.5%-25.9% of exposure dose) following 24 h contact with the studied fabrics. Estimated permeability coefficients (K_P, cm h^-1) showed TCEP had the highest percutaneous penetration potential followed by TCIPP, then TDCIPP. Further investigation revealed human dermal uptake of Cl-PFRs can be influenced by several factors including: the specific physicochemical properties of the compound, the type of exposure matrix, the exposure dose and the degree of skin hydration at the point of contact. Exposure assessment revealed UK adults and toddlers can be exposed to 20.4 and 14.1 ng TCIPP/kg bw/day via contact with furniture fabrics in summer, which is higher than international average exposures via inhalation and dust ingestion for adults and dietary exposure for toddlers. Therefore, risk assessment studies for Cl-PFRs and future replacements should consider dermal contact with consumer products (e.g. furniture fabrics) as a potential significant human exposure pathway.

Maternal urinary OPE metabolite concentrations and blood pressure during pregnancy: The HOME study

BACKGROUND

Few studies have examined the association between maternal exposure to organophosphate esters (OPEs) and systolic/diastolic blood pressure (SBP/DBP) during pregnancy.

METHODS

We analyzed data from 346 women with a singleton live birth in the HOME Study, a prospective birth cohort in Cincinnati, Ohio, USA. We quantified four OPE metabolites in maternal spot urine samples collected at 16 and 26 weeks pregnancy, standardized by specific gravity. We calculated intraclass correlation coefficients (ICCs). We extracted the first two recorded BP measurements (<20 weeks), the two highest recorded BP measurements (≥20 weeks), and diagnoses of hypertensive disorders of pregnancy (HDP) via chart review. Women with two BP measurements ≥140/90 mmHg or HDP noted in the chart at ≥20 weeks pregnancy were defined as HDP cases. We used linear mixed models and modified Poisson regression with covariate adjustment to estimate associations between OPE concentrations as continuous variables or in tertiles with maternal BP and HDP.

RESULTS

ICCs of OPEs were 0.17-0.45. Diphenyl phosphate (DPHP) had the highest geometric mean concentration among OPE metabolites. Increasing the average bis(2-chloroethyl) phosphate (BCEP) concentrations were positively associated with two highest recorded DBP ≥20 weeks pregnancy. Compared with women in the 1st DPHP tertile, women in the 3rd tertile at 16 weeks pregnancy had 1.72 mmHg (95% CI: -0.01, 3.46) higher DBP <20 weeks pregnancy, and women in the 3rd tertile of the average DPHP concentrations had 2.25 mmHg (95% CI: 0.25, 4.25) higher DBP ≥20 weeks pregnancy. 33 women (9.5%) were identified with HDP. Di-n-butyl phosphate (DNBP) concentrations at 16 weeks were positively associated with HDP, with borderline significance (RR = 2.98, 95% CI 0.97-9.15). Other OPE metabolites were not significantly associated with HDP.

CONCLUSION

Maternal urinary BCEP and DPHP concentrations were associated with increased BP during pregnancy. Maternal urinary DNBP concentrations were associated with HDP, with borderline significance.

Chemical Mixtures in Household Environments: In Silico Predictions and In Vitro Testing of Potential Joint Action on PPARγ in Human Liver Cells

There are thousands of chemicals that humans can be exposed to in their everyday environments, the majority of which are currently understudied and lack substantial testing for potential exposure and toxicity. This study aimed to implement in silico methods to characterize the chemicals that co-occur across chemical and product uses in our everyday household environments that also target a common molecular mediator, thus representing understudied mixtures that may exacerbate toxicity in humans. To detail, the Chemical and Products Database (CPDat) was queried to identify which chemicals co-occur across common exposure sources. Chemicals were preselected to include those that target an important mediator of cell health and toxicity, the peroxisome proliferator activated receptor gamma (PPARγ), in liver cells that were identified through query of the ToxCast/Tox21 database. These co-occurring chemicals were thus hypothesized to exert potential joint effects on PPARγ. To test this hypothesis, five commonly co-occurring chemicals (namely, benzyl cinnamate, butyl paraben, decanoic acid, eugenol, and sodium dodecyl sulfate) were tested individually and in combination for changes in the expression of PPARγ and its downstream target, insulin receptor (INSR), in human liver HepG2 cells. Results showed that these likely co-occurring chemicals in household environments increased both PPARγ and INSR expression more significantly when the exposures occurred as mixtures vs. as individual chemicals. Future studies will evaluate such chemical combinations across more doses, allowing for further quantification of the types of joint action while leveraging this method of chemical combination prioritization. This study demonstrates the utility of in silico-based methods to identify chemicals that co-occur in the environment for mixtures toxicity testing and highlights relationships between understudied chemicals and changes in PPARγ-associated signaling.

An overview of organic contaminants in indoor dust, their health impact, geographical distribution and recent extraction/analysis methods

People spend a substantial proportion of their time indoors; therefore, exposure to contaminants in indoor dust is persistent and profuse. According to the findings of recent studies, contaminants such as flame retardants (FRs), organochlorines (OCs), and phthalate esters (PAEs) are more prevalent in indoor dust. The discrepancy in the geographical distribution of these chemicals indicates country-specific applications. However, many studies have revealed that chlorophosphates, polychlorinated biphenyls (PCBs) and di-2-ethylhexyl phthalate are frequently detected in indoor dust throughout the world. Although some chemicals (e.g., OCs) were banned/severely restricted decades ago, they have still been detected in indoor dust. These organic contaminants have shown clear evidence of carcinogenic, neurotoxic, immunogenic, and estrogenic activities. Recent extraction methods have shown their advantages, such as high recoveries, less solvent consumption, less extraction time and simplicity of use. The latest separation techniques such as two-dimensional gas/liquid chromatography, latest ionization techniques (e.g., matrix-assisted laser desorption/ionization (MALDI)), and modern techniques of mass spectrometry (e.g., tandem mass spectrometry (MS/MS), time-of-flight (TOF) and high-resolution mass spectrometry (HRMS)) improve the detection limits, accuracy, reproducibility and simultaneous detection of organic contaminants. For future perspectives, it is suggested that the importance of the study of dust morphology for comprehensive risk analysis, introducing standard reference materials to strengthen the analytical methods, adopt common guidelines for comparison of research findings and the importance of dust analysis in the developing world since lack of records on the production and usage of hazardous substances. Such measures will help to evaluate the effectiveness of prevailing legislations and to set up new regulations.

Identifying dermal exposure as the dominant pathway of children's exposure to flame retardants in kindergartens

Exploration of multiple sources of brominated (BFRs) and organophosphate flame retardants (OPFRs) for children promotes the understanding of exposure pathways and health risk. 10 BFRs and 9 OPFRs were measured in skin wipes from hands, forehead, and arms of 30 children, and surface wipe samples from sills, toys, desks and floors, and indoor air samples of kindergartens from Xinxiang, China. Higher ∑₉OPFRs concentrations were observed in the forehead (1840 ng/m²), followed by hand (1420 ng/m²) and arm wipes (1130 ng/m²), and the ∑₈BFRs concentrations in forehead, hand and arm wipes were 116, 315 and 165 ng/m², respectively. The total concentration of OPFRs and BFRs in floor wipes (66.1 and 24.5 ng/m²) were lower than those in toy (205 and 535 ng/m²), sill (227 and 30.1 ng/m²) and desk (84.4 and 139 ng/m²) wipes. Concentrations of FRs in forehead wipes were significantly correlated with those in gaseous air (p < 0.05), moderate correlations were found between the hand wipes and surface wipes (p = 0.054). We estimated the daily average dosages (DADs) of children exposure to FRs via multiple pathways. Compared to DADs via inhalation and hand-to-mouth transfer, dermal exposure was determined to be the predominant exposure pathway to ∑₉OPFRs and ∑₈BFRs.

Electronic-Waste-Driven Pollution of Liquid Crystal Monomers: Environmental Occurrence and Human Exposure in Recycling Industrial Parks

Liquid crystal monomers (LCMs) in liquid crystal displays (LCDs) may be released into the environment, especially in electronic waste (e-waste) recycling industrial parks with a high pollution risk. However, little has been known about the environmental release and human exposure to LCMs until now. Herein, a total of 45 LCMs were detected in LCDs of commonly used smartphones and computers by high-resolution mass spectrometry with suspect screening analysis. Fluorinated biphenyls and their analogs were the dominant LCMs. Based on available standards of the screening results and previous studies, 55 LCMs were quantified in samples from an e-waste recycling industrial park in Central China. The LCMs were frequently detected in outdoor dust (n = 43), workshop #1 indoor dust (n = 53), and hand (n = 43) and forehead wipes (n = 43), with median concentrations of 6950 ng/g, 67,400 ng/g, 46,100 ng/m², and 62,100 ng/m², respectively. The median estimated daily intake values of the LCMs via dust ingestion and dermal absorption were 48.3 and 16.5 ng/kg body weight/day, respectively, indicating a high occupational exposure risk of these compounds. In addition, 16 LCMs were detected in the serum of eight elderly people (≥60 years old) with over 5 years of experience in e-waste dismantling operations, resulting in a total concentration range of 3.9-26.3 ng/mL.

Fast and Environment-Friendly GC-MS Method for Eleven Organophosphorus Flame Retardants in Indoor Air, Dust, and Skin Wipes

Organophosphorus based flame retardants (OPFRs) extensively used as alternatives to banned polybrominated diphenyl ethers and hexabromocyclododecane have been garnering interest due to the possibility that these compounds may have less significant impact on human and environmental health. Long pretreatment time, larger consumption of organic solvents, matrix interferents, and cross-contamination were found in previous studies while assessing OPFRs in indoor environments. We developed and optimized the extraction methods and simultaneous analysis of 11 OPFRs in indoor air, dust and skin wipe samples using the GC-MS approach. The proposed methods were validated using a standard addition approach, dust SRM 2585 and the real samples. Our procedures enabled the analyst to effectively limit coextracted interferences and simultaneous analytical methods of 11 target OPFRs for three matrices were achieved. The validation was performed according to standard guidelines (relative errors were identified by the analytes: −19% to 18% for indoor air, −11% to 14% for house dust, −15% to 16% for skin wipe). Good practices for quality assurance and quality control were well stated. The current high-Eco-scored methods could be categorized as “an excellent green analysis”. All analytes for the target OPFRs were detected in the real samples of indoor air, house dust and skin wipe collected from ten Taiwanese homes. Tris(2-butoxyethyl) phosphate, tris(1,3-dichloro-2-propyl)phosphate and tris(chloroisopropyl) phosphate were the most abundant OPFRs. Rapid, green and cost-effective GC-MS methods were developed and validated for the analysis of eleven OPFRs in indoor air, house dust and skin wipes.

Measurement of polychlorinated biphenyls with hand wipes and matched serum collected from Chinese E-waste dismantling workers: Exposure estimates and implications

To date, dermal/hand-to-mouth exposure to chemicals in the e-waste recycling environment has not been sufficiently understood, and the importance of dermal absorption of chemicals in e-waste dismantling workers remains controversial. In this study, we utilized hand wipes and matched sera to characterize dermal/hand-to-mouth exposure to PCBs for e-waste dismantling workers, and potential effects on thyroid hormones were also assessed. PCB loadings in hand wipes varied from 0.829-265 ng wipe^-1 (11.3-2850 ng m^-2 wipe^-1), with 37.2 ng wipe^-1 (432 ng m^-2 wipe^-1) as the median value. Serum concentrations of PCBs ranged from 32.3-3410 ng g^-1 lipid weight (lw) with 364 ng g^-1 lw as the median value. Between wipes and sera, lower-chlorinated congeners (e.g. CB-28, -66, -74, -99,-105 and -118) showed significant associations (p < 0.01), but higher-chlorinated congeners (e.g. CB-138, -153, -156, -170, and -180) did not. These lower-chlorinated CBs were the major contributors to estimated dermal/hand-to-mouth average daily doses (ADDs) and the hazard index (HI). Correspondingly, their estimated contributions to serum levels by dermal absorption were also significant, with the contribution of CB-28 being as high as 21.4%. As a consequence, dermal absorption of some low-chlorinated congeners was a non-negligible route for e-waste dismantling workers. Although insignificant association was shown between serum PCBs and thyroid hormones, the potential health risk should be of concern due to the high levels of PCBs observed in workers' sera.

Occurrence of novel organophosphate esters derived from organophosphite antioxidants in an e-waste dismantling area: Associations between hand wipes and dust

Electronic waste (e-waste) is a well-known source of plastic additives in the environment. However, the e-waste-related occupational exposure to organophosphite antioxidants (OPAs) and the relevant oxidation products-novel organophosphate esters (NOPEs)-via different pathways is still unknown. In this study, six OPAs and three NOPEs were measured in 116 dust and 43 hand-wipe samples from an e-waste dismantling area in Central China. The median concentrations of ΣOPAs and ΣNOPEs were 188 and 13,900 ng·g^-1 in workshop dust and 5,250 ng·m^-2 and 53,600 ng·m^-2 on workers' hands, respectively. The increasing concentrations of dust in the form of triphenyl phosphate (TPHP) (p < 0.01) and tris(2,4-di-tert-butylphenyl) phosphate (AO168 = O) (p < 0.05) were strongly associated with the corresponding concentration on workers' hands. Furthermore, men had significantly lower levels of NOPEs on their hands than did women (p < 0.01). Moreover, the hand wipe levels of AO168 = O (41,600 ng·m^-2) was significantly higher than that of the typical OPE (TPHP, 7370 ng·m^-2), and the hand-to-mouth contact (ΣOPAs, 9.48 ng·kg bw^-1·day^-1; ΣNOPEs, 109 ng·kg bw^-1·day^-1) was a more significant and integrated pathway than dust ingestion (ΣOPAs, 0.10 ng·kg bw^-1·day^-1; ΣNOPEs, 5.01 ng·kg bw^-1·day^-1) of e-waste related occupational exposure to these "new" chemicals.