Organophosphate Flame Retardants Research Articles

Photoelectrocatalytic degradation of organophosphate esters using tio2 electrodes produced from 3d-printed ti substrates.

3D printed electrode substrates with novel geometries may significantly improve the efficacy of photoelectrocatalysis for degradation of recalcitrant pollutants such as organophosphate flame retardants (OPFRs). However, the 3D printed substrates often have an irregular topology that can lead to a less uniform arrangement of nanotubes following anodisation. This study investigated the effect of polishing 3D-printed Ti substrates prior to anodisation to form TiO2 nanotube array electrodes, and their subsequent applicability for photoelectrocatalytic treatment of OPFRs in water matrices. Polished and non-polished electrodes exhibited differences in morphology in terms of average roughness, (0.38 and 3.10µm, respectively), leading to more uniform TiO2 nanotubes of the former. Water contact angle measurements revealed the non-polished electrode was super-hydrophilic and the polished electrode hydrophilic (water contact angles of 6.4˚ and 16.1˚, respectively). Despite these differences, the polished and non-polished electrodes exhibited very similar electrochemical responses. In fact, the purity and electrical conductivity of water matrices affected the photoelectrocatalytic performance more than the electrode morphology. The purified water (PW) matrix facilitated the highest degradation/removal of OPFRs, compared to tap water matrices. In particular, individual OPFR degradation levels in PW were 74% ± 9, 37% ± 10, 33% ± 9, 31% ± 11 and 3% ± 5 for triphenyl phosphate, tris(butyl) phosphate, tris(isobutyl) phosphate, tris(2-butoxyethyl) phosphate and tris(2-chloroisopropyl) phosphate, respectively. The removal of OPFRs was relative to their reactivity to hydroxyl radicals, which was higher for the aryl then alkyl straight-chain and then chlorinated compounds. This study reveals that polishing of electrode substrates is not required for the preparation of effective photoelectrocatalytic reactors to treat recalcitrant pollutants (e.g. OPFRs), Importantly, future development of novel high-profile 3D printed electrode will not be hindered by the requirement to polish the substrates prior to anodisation.

Oxidative stress mediates the association of organophosphate flame retardants with metabolic obesity in U.S. adults: A combined epidemiologic and bioinformatic study

Obesity is a global public health issue, with limited epidemiologic studies on the relationship and mechanisms between organophosphate flame retardants (OPFRs) and metabolic obesity phenotypes (MOPs). We aimed to explore the link between OPFRs metabolite (m-OPFRs) and MOPs using a combined epidemiologic and bioinformatic approach. We used cross-sectional survey data from the U.S. National Health and Nutrition Examination Survey (2011–2018) to analyze the relationship between m-OPFRs and metabolic health obesity (MHO), as well as metabolic unhealthy obesity (MUO). The dataset encompasses eligible adults to assess the impact of individual, mixed, and mediated effects on the outcome variables through multivariate logistic regression, Bayesian kernel machine regression (BKMR), and mediation analysis. Multiple logistic regression models, stratified by tertiles of exposure showed that bis(1,3-dichloro-2-propyl) phosphate (BDCIPP) levels in the body significantly increased the risk of MHO, with OR and 95%CI of 1.454 (1.082, 1.953) for the second tertile (T2) and 1.598 (1.126, 2.268) for the third tertile (T3), compared to the first tertile (T1). Increased levels of BDCIPP in T3 (1.452(1.013, 2.081)) are associated with MUO, compared to T1. Mixed m-OPFRs and MHO risk in BMKR were positively correlated, with BDCIPP being the primary contributor. We found that the serum uric acid (SUA) and white blood cell count (WBC) indicators significantly mediated the association between BDCIPP and MHO (P < 0.05). Our study suggests that OPFRs, either individual or mixed, are associated with two distinct MOPs, with oxidative stress playing an important role. In addition, in silico analysis was used to screen for shared genes, and eight shared genes and eleven biological pathways identified during the screening process were used to construct the adverse outcome pathway, which suggests that exposure to OPFRs may activate the peroxisome proliferator-activated receptor (PPAR) pathway, thereby increasing the risk of obesity. Further studies are needed to validate our findings.

Effects of urinary organophosphate flame retardants in susceptibility to attention-deficit/hyperactivity disorder in school-age children

Our previous studies have revealed a correlation between urinary phthalates (PAE) metabolites and parabens and PM2.5 exposure and susceptibility to attention-deficit/hyperactivity disorder (ADHD) in school-age children. Our goal was to examine the relationships between urinary organophosphate flame retardants (OPFRs) and their metabolites and the susceptibility to ADHD in the same cohort of children. We recruited 186 school children, including 132 with ADHD and 54 normal controls, living in southern Taiwan to investigate five OPFRs (1,3-dichloro-2-propyl phosphate (TDCPP), tri-n-butyl phosphate (TnBP), tris (2-chloroethyl) phosphate (TCEP), tris(2-butoxyethyl) phosphate (TBEP), and triphenyl phosphate (TPHP)) and five OPFR metabolites (bis(1,3-dichloro-2-propyl) phosphate (BDCPP), di-n-butyl phosphate (DNBP), bis(2-chloroethyl) hydrogen phosphate (BCEP), di-(2-butoxyethyl) phosphate (DBEP), and diphenyl phosphate (DPHP)) in urine. ADHD patients’ behavioral symptoms and neuropsychological function were assessed using the Swanson, Nolan, and Pelham Version IV Scale (SNAP-IV) and the Conners’ Continuous Performance Test 3rd Edition (Conners CPT3), respectively. BCEP was predominant among urinary OPFRs and the metabolites in both the ADHD and control groups. ADHD children had significantly higher levels of urinary BDCPP, BCEP, DBEP, DPHP, TCEP, TBEP, TNBP, TPHP, and Σ10OPFR compared to the controls. After controlling for age, gender, body mass index, PM2.5 exposure scenarios, and urinary phthalate metabolites, parabens, bisphenol-A and creatinine, levels of urinary BDCPP, TDCPP, and TBEP in ADHD children showed significant and dose-dependent effects on core behavioral symptoms of inattention. DNBP levels were positively correlated with neuropsychological deficits (CPT detectability, omission, and commission), while urinary DPHP in ADHD children were negatively related to CPT detectability and commission. Hyperactivity and impulsivity were not correlated with urinary OPFRs and their metabolites in ADHD children. In conclusion, the ADHD symptom of inattention and CPT performance may be closely associated with certain urinary OPFRs and their metabolites, independent of urinary PAE metabolites, parabens, and bisphenol-A in school-age-ADHD children.

Biodegradation of tri-butyl phosphate by Trametes versicolor and its application in a trickle bed reactor under non-sterile conditions

Tri-butyl phosphate (TBP) is a widely used organophosphate flame retardant. However, it is also regarded as emerging contaminant due to its various toxic effects and poor removal by conventional wastewater treatment. In present study, we investigated the degradation of TBP (10 mg/L) by the white rot fungus Trametes versicolor in both laboratory conditions and a trickle bed reactor (TBR) under non-sterile conditions. The removal yield reached 98 % after 3 days, during which the intracellular enzymatic system cytochrome P450 was involved. Four transformation products (TPs) were identified, namely dibutyl 3-hydroxybutyl phosphate, dibutyl phosphate, butyl 3-hydroxybutyl phosphate and butyl dihydrogen phosphate, which allowed us to propose a degradation pathway where hydroxylation and hydrolysis made considerable contribution. TBP treatment in the TBR with T. versicolor immobilized on wood chips operating in sequential batch mode with 10 cycles of 3 days reached average removals higher than 93 %, demonstrating the potential for practical application. Despite similar removal rates in heat-killed and abiotic controls (89 % and 97 %, respectively), global mass balance analysis indicated 86 %, 64 %, and 86 % removal by degradation in the fungal, heat-killed, and abiotic controls, respectively. Analysis of the microbial assemblage in solid phase suggested that the established bacterial populations displayed a synergistic effect with immobilized fungus. This study is the first to report on TBP degradation by T. versicolor in a TBR under non-sterile conditions, suggesting that this method could be a viable option for large-scale environmental applications.

Spherical covalent-organic framework-assisted laser desorption ionization mass spectrometry reveals the promotional effect of triphenyl phosphate on breast cancer in mice

Triphenyl phosphate (TPP), a wide-used organophosphate flame retardants (OPFRs), is suspected to be a risk factor for the female-specific cancers, but underlying toxicity mechanisms of environmentally relevant dose exposure remain unclear. Herein, a strategy of spherical covalent organic framework (TPB-BPTP-COF)-assisted laser desorption ionization mass spectrometry (LDI-MS), which benefited from fast analysis speed, facile sample preprocessing, and high throughput, was proposed for unveiling the biomarkers of breast cancer (BC) and the relationship between TPP exposure and progression of BC in mice by serum metabolism analysis. The results displayed that 13 metabolites associated with BC development were up-regulated in experimental group versus healthy control mice. Moreover, long-term exposure to environmentally relevant doses of TPP was found to promote BC, mainly by affecting glycolysis/gluconeogenesis, pyrimidine metabolism, pantothenic acid and CoA biosynthesis, and β-alanine metabolism. This work proved the potential application of COFs as LDI-MS substrates in analyzing complex biological samples, and also revealed the risk of long-term low-dose exposure to TPP in the development of BC.

Tri-iso-butyl phosphate (TiBP) exposure induces neurotoxicity by triggering oxidative stress accompanied by neurotransmitter system disruptions and apoptosis in zebrafish larvae

The current research sheds light on the biological toxicity of organophosphate flame retardants (OPFRs), yet it overlooks the neurotoxicity and potential molecular mechanisms of tris(1,3-dichloro-2-propyl) phosphate (TiBP), a prominent constituent of the OPFRs. To address this, we utilized zebrafish larvae as a model to investigate TiBP's acute toxicity and neurotoxic effects, along with the associated molecular pathways. Our findings revealed that the 96 h and 120 h LC50 values for TiBP were 56.51 mg/L and 48.85 mg/L, respectively. Gradient exposure based on the 120 h LC50 demonstrated that TiBP induced developmental toxicity, characterized by elevated heart rate, reduced body length, and diminished eye distance. Additionally, a decrease in swimming activity was observed in the light test, along with the inhibition of the neuro crest cell development in Tg (HuC:eGFP) and Tg (sox10: eGFP) zebrafish larvae following TiBP exposure, as well as the alterations of neurogenesis and ACh-related genes. Expression of key neurodevelopment genes, including mbpa, gap43, nestin, ngfra, was significantly downregulated. Furthermore, heightened anxiety-like behaviors in open field and phototaxis tests were observed, concomitant with neurotransmitter imbalances. Specifically, there was an increase in DA levels, a decrease in GABA, and an upregulation of AChE activity. These disruptions were primarily mediated through transcriptional dysregulation of neurotransmitter synthesis, transport, and reception. Upon exposure to TiBP, zebrafish larvae exhibited a concentration-dependent increase in both ROS level and apoptosis. An upregulation of antioxidant enzymes and their transcription levels indicated the presence of oxidative stress in the larvae. The induction of ddit3 was congruent with the observed apoptosis, suggesting that it may be triggered by oxidative stress via the ERs-CHOP pathway. In summary, our study indicates that oxidative stress is a pivotal molecular event in the neurotoxicity induced by TiBP, implicating the disruption of the GABAergic, dopaminergic, and cholinergic systems, as well as triggering apoptosis.

From flames to lab: A robust non-destructive sampling method for evaluating PAH exposure in firefighters’ personal protection equipment

Polycyclic aromatic hydrocarbons (PAHs) are compounds with high carcinogenic potential, produced during incomplete combustion. Certain professions, such as firefighting, expose workers to significant levels of PAHs during their operations, making it essential to investigate sampling protocols to evaluate their exposure in the work environment.This study presents a non-destructive and cost-effective sampling method for monitoring PAHs in firefighters’ personal protective equipment (PPE) and intervention vehicles. Sampling was conducted using three isopropanol wipes per collection zone, with comprehensive validation trials ensuring the method’s effectivenes. The method was tested under both natural contamination and spiking scenarios, showing similar results in both protocols.Analysis of contaminated PPE revealed significant PAH contamination in specific zones, such as gloves, lower back sleeves, and knees, due to direct exposure to flames and smoke during firefighting, with the highest concentrations in the outer and moisture layers. The cleaning efficacy of PPE was also evaluated employing specific washing machines, showing substantial reductions in PAH levels of approximately 76%. Additionally, non-targeted analysis detected organophosphate flame retardants (OPFRs) and furans, suggesting broader utility for environmental monitoring. This comprehensive approach improves the accessibility of chemical exposure studies in high-risk professions, contributing to better protective measures and occupational health and safety.

Removal of TBP sorbed on wood by Trametes versicolor through solid-state fermentation

The use of white-rot fungi is a promising approach for removing organophosphate flame retardants (OPFRs) from wastewaters. Immobilization in wood for this purpose ensures the predominance of the fungus but also contributes to OPFRs sorption. This work focused on the ability of T. versicolor to degrade tributyl phosphate (TBP) sorbed in wood. This initially underwent ten sorption cycles, each involving exposure to a 10mg · L-1 TBP solution. Throughout each cycle, the wood exhibited a sustained sorption capacity (0.035 ± 0.002mg TBP · g. dry wood-1 per cycle). The wood residues obtained after each sorption cycle were inoculated with T. versicolor. After 60 days of inoculation, fungus degraded over 90% of TBP in each cycle’s wood residue. However, fungal growth was inhibited, resulting in a 43% decrease in biomass compared to controls. The fact that biomass remained active and capable of degrading TBP suggests that the growth decrease is likely due to the formation of transformation products. An increase in toxicity units (from 13.64 to 87.86 at the end) was associated with the accumulation of 3-hydroxybutyl dihydrogen phosphate (OH-MBP). However, subsequent experiments demonstrated that given sufficient time, the fungus not only degraded OH-MBP but also produced a non-toxic effluent.

Occurrence of legacy and emerging organophosphate flame retardants (OPFRs) on silicone wristbands: Comparison within couples

Novel organophosphate flame retardants (OPFRs) are recently identified and highly detected in indoor dusts, but their personal exposure was not clear. Here, wristband was used to estimate non-dietary exposure to emerging OPFRs in comparison with legacy OPFRs in 93 adults in Beijing, China. Comparison of studies in wristband monitoring data showed a clear difference in profiles of legacy OPFRs between China and United States, where tris(1,3-dichloro-2-propyl) phosphate (TDCIPP) was usually the dominant OPFR in the United States, but triphenyl phosphate has the highest contribution to total OPFRs in China. Five emerging OPFRs, including diethylene glycol bis(bis(2-chloroisopropyl) phosphate) (DEGBBCPP) and bis(2-ethylhexyl) phenyl phosphate (BEHPP), were detected in above 45 % of wristbands. The median concentration of DEGBBCPP (2.2 ng/g) was about three times higher than TDCIPP (0.76 ng/g), a legacy chloro-OPFR. Both emerging and legacy OPFRs were significantly correlated within 40 pairs of couples, suggesting major exposure in their homes. Wristbands from husbands had significantly higher tris(2-butoxyethyl) phosphate (TBOEP) and DEGBBCPP, while 2-ethylhexyl diphenyl phosphate (EHDPP) was significantly higher in wives' bands, suggesting gender-related exposure sources for these OPFRs.

Regrettable Substitution? Organophosphate Flame Retardants and Macrophage Activity.

Certain immune cells exposed to a mixture of organophosphate esters showed changes in their function and biology. The mixture included chemicals detected in samples of house dust.

Occurrence of organophosphate flame retardants in agricultural products from Korean markets

Organophosphate flame retardants (OPFRs) are widely used in various products encountered in daily life including home appliances, furniture, and plastics. This study developed a method to determine the presence of 11 OPFRs in agricultural products to monitor OPFR contamination in Korean local markets. The method was based on QuEChERS extraction with liquid chromatography-tandem mass spectrometry using gradient elution with a run time of 13 min. The selectivity, linearity, limit of detection (LOD), limit of quantification (LOQ), recovery, and precision of developed method were validated based on the CODEX guidelines. The LOD values for 11 OPFRs ranged from 0.05 to 0.66 ng/g, which were comparable to the values obtained in previous studies. The established method was successfully applied to agricultural products collected in a Korean market. A 32 product types with seven replicates (total 224 samples) were monitored for OPFR contamination. These products included popular fruits and vegetables in Korea such as apples, cucumber, corn, etc. The agricultural products with the highest average of total OPFR concentration was eggplants (12.50 ng/g ww), and the OPFR types with the highest average concentration across all tested agricultural products was tris (1-chloropropan-2-yl) phosphate (TCIPP), with an average value of 1.48 ng/g. The estimated daily intake values were much lower than the reference dose values of OPFRs, which showed that exposure to OPFRs through agricultural products is generally safe. The results of this study could be used as the basis for expanding monitoring of OPFRs to aquatic and meat products, and will also be helpful in informing industries about the current risk of OPFR contamination.

Breast Cancer-Related Chemical Exposures in Firefighters.

To fill a research gap on firefighter exposures and breast cancer risk, and guide exposure reduction, we aimed to identify firefighter occupational exposures linked to breast cancer. We conducted a systematic search and review to identify firefighter chemical exposures and then identified the subset that was associated with breast cancer. To do this, we compared the firefighter exposures with chemicals that have been shown to increase breast cancer risk in epidemiological studies or increase mammary gland tumors in experimental toxicology studies. For each exposure, we assigned a strength of evidence for the association with firefighter occupation and for the association with breast cancer risk. We identified twelve chemicals or chemical groups that were both linked to breast cancer and were firefighter occupational exposures, including polycyclic aromatic hydrocarbons, volatile aromatics, per- and polyfluoroalkyl substances, persistent organohalogens, and halogenated organophosphate flame retardants. Many of these were found at elevated levels in firefighting environments and were statistically significantly higher in firefighters after firefighting or when compared to the general population. Common exposure sources included combustion byproducts, diesel fuel and exhaust, firefighting foams, and flame retardants. Our findings highlight breast-cancer-related chemical exposures in the firefighting profession to guide equitable worker's compensation policies and exposure reduction.

Occurrence and Distribution of Organophosphate Flame Retardants in Tap Water System-Implications for Human Exposure from Shanghai, China.

The pollution of organophosphate flame retardants (OPFRs) is of global concern, but the site-specific data of OPFR concentrations in drinking water are scarce for many areas of the world outside of Europe and the US. This study aimed to investigate the occurrence and profiles of OPFRs in the tap water treatment and delivery process in Shanghai. In total, 106 samples were analyzed for 10 OPFRs, which were collected periodically from monitoring points of drinking water treatment plants and piped water between November 2021 and July 2023. The average daily doses of OPFRs through the ingestion of tap water were calculated by multiplying nominal volumes of water ingestion rates with the measured concentrations of OPFRs. Hazard quotients, the hazard index, and the carcinogenic risks of OPFRs via drinking water were used to estimate the health risks. Tributyl phosphate (TBP), tris(2-chloroethyl) phosphate (TCEP), and tris (1-chloro-2-propyl) phosphate (TCIPP) were found in >90% of the tap water samples, whereas triethyl phosphate (TEP) and tris (2,3-dibromopropyl) phosphate (TDBPP) were not found in any samples. The concentrations of Σ10OPFRs were found at part-per-trillion ranges, with average concentrations that ranged from 86.0 ng/L in February 2023 (dry season) to 218 ng/L in July 2022 (wet season). TCIPP was the most abundant compound among the investigated OPFRs. The average daily dose of Σ10OPFRs via the ingestion of tap water was up to 20.4 ng/kg body weight/day. The hazard quotients of OPFRs through drinking water were in the range of 10-5-10-4, indicating low risk levels. Moreover, the hazard index of OPFRs indicated that the risk for children (2 × 10-4) was higher than adults (7 × 10-5). Tap water intake may be an important source of OPFRs exposure. But the risk of OPFRs for local residents is at a low level through drinking water.

Urinary Concentrations of Organophosphate Flame-Retardant Metabolites in the US Population

Organophosphate flame retardants (OPFRs) are an important group of pollutants associated with endocrine disorders, cancer, and nephrotoxicity. However, temporal trends in OPFR metabolite concentrations remain understudied. To examine changes in urinary concentrations of OPFR metabolites among US children, youths, and adults from 2011 to 2020, and to evaluate whether sociodemographic factors were associated with variations in temporal trends. This population-based cross-sectional study used data from 4 US National Health and Nutrition Examination Survey (NHANES) cycles (2011-2012, 2013-2014, 2015-2016, and 2017-2020 [to March 2020 before the COVID-19 pandemic]). The study included children and youths (aged 6-19 years) and adults (aged ≥20 years) with valid urinary concentrations of the following OPFR metabolites: bis(2-chloroethyl) phosphate (BCEtP), bis(1-chloro-2-propyl) phosphate (BCPP), diphenyl phosphate (DPhP), and dibutyl phosphate (DBuP). Data analysis was performed between February and May 2024. Calendar year and key sociodemographic subgroups (age, race and ethnicity, sex, educational attainment, and poverty-to-income ratio). The main outcome was urinary concentrations of OPFR metabolites among children, youths, and adults. Survey-weighted linear regression models were applied to estimate trends. The study population of 10 549 NHANES participants included 3154 children and youths (mean [SE] age, 12.5 [0.1] years; 51.2% were male) and 7395 adults (mean [SE] age, 47.8 [0.4] years; 52.0% were women). Among children and youths, mean (95% CI) BCEtP concentrations decreased from 0.68 (0.60-0.77) μg/L in 2011-2012 to 0.41 (0.37-0.45) μg/L in 2017-2020 (P for trend < .001). Among adults, mean (95% CI) BCEtP concentrations decreased from 0.43 (0.37-0.50) μg/L in 2011-2012 to 0.29 (0.27-0.33) μg/L in 2017-2020 (P for trend < .001), and mean BCPP concentrations decreased from 0.15 (0.14-0.17) μg/L to 0.13 (0.12-0.14) μg/L (P for trend = .002). Parent level of educational attainment was associated with concentrations of BCPP and BCEtP among children and youths; however, no significant differences among adults were observed. This study identified variations in temporal trends in urinary concentrations of OPFR metabolites among the US population from 2011 to 2020. In addition, substantial disparities in exposure levels persisted among children with different levels of parent educational attainment. These findings suggest that policy makers should consider socioeconomic factors to further reduce OPFR exposure and promote equity, ensuring a safe living environment for all individuals.

Triphenyl Phosphate Alters Methyltransferase Expression and Induces Genome-Wide Aberrant DNA Methylation in Zebrafish Larvae.

Emerging environmental contaminants, organophosphate flame retardants (OPFRs), pose significant threats to ecosystems and human health. Despite numerous studies reporting the toxic effects of OPFRs, research on their epigenetic alterations remains limited. In this study, we investigated the effects of exposure to 2-ethylhexyl diphenyl phosphate (EHDPP), tricresyl phosphate (TMPP), and triphenyl phosphate (TPHP) on DNA methylation patterns during zebrafish embryonic development. We assessed general toxicity and morphological changes, measured global DNA methylation and hydroxymethylation levels, and evaluated DNA methyltransferase (DNMT) enzyme activity, as well as mRNA expression of DNMTs and ten-eleven translocation (TET) methylcytosine dioxygenase genes. Additionally, we analyzed genome-wide methylation patterns in zebrafish larvae using reduced-representation bisulfite sequencing. Our morphological assessment revealed no general toxicity, but a statistically significant yet subtle decrease in body length following exposure to TMPP and EHDPP, along with a reduction in head height after TPHP exposure, was observed. Eye diameter and head width were unaffected by any of the OPFRs. There were no significant changes in global DNA methylation levels in any exposure group, and TMPP showed no clear effect on DNMT expression. However, EHDPP significantly decreased only DNMT1 expression, while TPHP exposure reduced the expression of several DNMT orthologues and TETs in zebrafish larvae, leading to genome-wide aberrant DNA methylation. Differential methylation occurred primarily in introns (43%) and intergenic regions (37%), with 9% and 10% occurring in exons and promoter regions, respectively. Pathway enrichment analysis of differentially methylated region-associated genes indicated that TPHP exposure enhanced several biological and molecular functions corresponding to metabolism and neurological development. KEGG enrichment analysis further revealed TPHP-mediated potential effects on several signaling pathways including TGFβ, cytokine, and insulin signaling. This study identifies specific changes in DNA methylation in zebrafish larvae after TPHP exposure and brings novel insights into the epigenetic mode of action of TPHP.

From e-waste to living space: Flame retardants contaminating household items add to concern about plastic recycling

Brominated flame retardants (BFRs) and organophosphate flame retardants (OPFRs) are commonly used in electric and electronic products in high concentrations to prevent or retard fire. Health concerns related to flame retardants (FRs) include carcinogenicity, endocrine disruption, neurotoxicity, and reproductive and developmental toxicity. Globally, a lack of transparency related to chemicals in products and limited restrictions on use of FRs in electronics have led to widespread use and dissemination of harmful FRs. Despite the lack of transparency and restrictions, plastics from electronics are often recycled and can be incorporated in household items that do not require flame retardancy, resulting in potentially high and unnecessary exposure. This study sought to determine whether black plastic household products sold on the U.S. market contained emerging and phased-out FRs and whether polymer type was predictive of contamination. A total of 203 products were screened for bromine (Br), and products containing >50 ppm Br were analyzed for BFRs, OPFRs, and plastic polymers (e.g. acrylonitrile butadiene styrene, high impact polystyrene, polypropylene). FRs were found in 85% of analyzed products, with total FR concentrations ranging up to 22,800 mg/kg. FRs detected include the restricted compound deca-BDE, which was used widely in electronics casings, as well as its replacements decabromodiphenyl ethane (DBDPE) and 2,4,6-Tris(2,4,6-tribromophenoxy)-1,3,5-triazine (TBPP-TAZ) along with associated compound 2,4,6-tribromophenol (2,4,6-TBP), recently detected in breast milk. Plastic typically used in electronics (styrene-based) contained significantly higher levels of ∑FRs than plastics less typically used for electronics (polypropylene and nylon). Estimation of exposure to BDE-209 from contaminated kitchen utensils indicated users would have a median intake of 34,700 ng/day, exceeding estimates for intake from dust and diet. The detection of FRs in collected household products indicates that recycling, without the necessary transparency and restrictions to ensure safety, is resulting in unexpected exposure to toxic flame retardants in household items.

Global Gridded Emission Inventory of Organophosphate Flame Retardants from 2010 to 2020.

As a substitute for brominated flame retardants, organophosphate flame retardants (OPFRs) have become a global concern due to their high toxicity and bioaccumulation. To paint an overall picture of OPFRs in the global environment, the present study develops a gridded global emission inventory of OPFRs on a spatial resolution of 1 × 1° from 2010 to 2020. Revealing a 3.31% average annual increase in emissions, totaling 21,324.42 tons. The production process is the primary source, accounting for 55.43% of emissions, with consumption processes making up the rest. Major sources are in Asia, North America, and Europe. The inventory is verified by implementing emission data into a global atmospheric transport model to predict OPFR concentrations in the global environment and comparing modeled concentrations with field sampled data. The results indicate that the inventory is reliable except for the pristine polar region, where the emission inventory and modeled concentrations underestimate OPFR levels in the atmosphere, likely resulting from ignorance of chemical reactions and the secondary derivative of parent OPFRs during their global long-distance atmospheric transport in the model. This comprehensive data set aids in formulating OPFR emission control policies and assessing health risks.

Unveiling the mechanisms of reproductive toxicity induced by full life-cycle exposure to environmentally relevant concentrations of tris(2-chloroethyl) phosphate in male zebrafish

Tris (2-chloroethyl) phosphate (TCEP), a commonly used organophosphate flame retardant, has garnered considerable concern owing to its pervasive presence in the environment and its toxic effects on living organisms. The perpetuation of populations and species hinges on successful reproduction, yet research into the mechanisms underlying reproductive toxicity remains scant, particularly in aquatic species. In this work, zebrafish embryos were exposed to TCEP (0, 0.8, 4, 20, and 100 µg/L) for 120 days until sexual maturation, and multiple reproductive endpoints were investigated in male zebrafish. Our results showed that the body weight, body length, and gonadal-somatic index (GSI) were remarkably decreased in all TCEP treatment groups (except GSI in the 0.8 µg/L TCEP-treated group). Long-term exposure to TCEP led to reduced reproductive capacity of male zebrafish, as evidenced by decreased fertilization. Histological observation gave an indication of delayed testicular development and inhibited spermatogenesis under TCEP stress. The content of testosterone (T) was significantly elevated in all TCEP treatment group, whereas 17 β-estradiol (E2) levels remained stable. Transcriptome analysis revealed a lot of downregulated genes involved in steroid hormone biosynthesis, energy metabolism, and sperm motility, which might account for the imbalance of steroid hormone levels, retarded spermatogenesis and declined fertilization success. Overall, these findings offered a thorough understanding of the mechanisms underlying the male reproductive toxicity caused by TCEP, highlight the risk of TCEP on reproductive health of fish.

Exposure levels and maternal transfer of emerging organophosphate flame retardants (OPFRs) in pregnant women: Comparison with traditional OPFRs

Prenatal exposure to organophosphorus flame retardants (OPFRs) has been linked with adverse effects on reproductive health, and new OPFRs are continually emerging. In this study, emerging OPFRs, such as bis(2-ethylhexyl) phenyl phosphate (BEHPP), triamyl phosphate (TAP), tris(4-tert-butylphenyl) phosphate (T4tBPPP), oxydi-2,1-ethanediyl phosphoric acid tetrakis(2 chloro-1-methylethyl) ester (RDT905), cresyl diphenyl phosphate (CDP), and 2-isopropylphenyl diphenyl phosphate (2IPPDPP), were detected in 84 %, 100 %, 100 %, 52 %, 40 %, and 40 % of 25 decidua samples with average concentrations of 2.36, 6.21, 1.5, 2.6, 1.07, and 0.09 ng/g of dry weight (dw), respectively. Six of the aforementioned emerging OPFRs (BEHPP, T4tBPPP, RDT905, 2IPPDPP, CDP, and TAP) were simultaneously detected in paired chorionic villus samples, and their average concentrations were 11.3, 1.77, 3.64, 0.11, 0.58, and 3.34 ng/g, which were significantly higher than and positively correlated with those in decidua samples. The geometric mean concentration ratios between chorionic villus and decidua samples for BEHPP, T4tBPPP, RDT905, 2IPPDPP, CDP, and TAP were 4.02, 1.61, 1.73, 1.48, 0.82, and 0.69, respectively, consistent with transthyretin binding-dependent behavior. Prenatal exposure to such emerging OPFRs, especially for BEHPP with relatively high concentration and maternal transfer, is of high concern from the view of women’s reproductive health.

Source identification and human exposure assessment of organophosphate flame retardants and plasticisers in soil and outdoor dust from Nigerian e-waste dismantling and dumpsites

Electronic waste (e-waste) dismantling and dumpsite processes are major sources of organophosphate flame retardant and plasticiser emissions and may pose potentially adverse effects on environment and human health. In 20 outdoor dust and 49 soil samples collected from four e-waste dismantling and three e-waste dumpsites in two States of Nigeria (Lagos and Ogun), we identified 13 alternative plasticisers (APs), 7 legacy phthalate plasticisers (LPs), and 17 organophosphorus flame retardants (OPFRs) for the first time in African e-waste streams. In the samples from dismantling sites, the range (median) concentrations of ∑13APs, ∑7LPs, and ∑17OPFRs were 11 to 2747 μg/g (144 μg/g), 11 to 396 μg/g (125 μg/g), and 0.2 to 68 μg/g (5.5 μg), in dust respectively and 1.8 to 297 μg/g (55 μg/g), 1.3 to 274 μg/g (48.5 μg/g), and 1.6 to 62 μg/g (1.6 μg/g), in soil respectively. Results for soil samples from e-waste dumpsites were (6.6 to 195 μg/g (23.7 μg/g), 6.0 to 295 μg/g (54.8), and 0.4 to 42.3 μg/g (9.0 μg/g) for ∑13APs, ∑7LPs, and ∑17OPFRs respectively. Overall, concentrations of APs were significantly higher at the dismantling sites (p = 0.005) compared to dumpsites, levels of LPs were higher at dismantling sites but not significant, while OPFR concentrations were significantly higher in dumpsite samples (p = 0.005). Plasticisers were found to be major contributors to pollution at e-waste dismantling sites, while OPFRs were associated with both automobile dismantling and e-waste dumpsite processes. Following particle size fractionation of selected soil samples, higher concentrations of targeted compounds were observed in the smaller mesh (180 μm) soil sieve fraction. For dust, the total median estimated daily intake via ingestion and dermal adsorption (EDIing and EDIderm) ranged from 43 to 74 ng/kg bw/day and 0.4 to 0.7 ng/kg bw/day, respectively. Correspondingly, 4.6 to 45 ng/kg bw/day and 0.015 to 0.57 ng/kg bw/day were the values found for soil, respectively. According to these results, the targeted chemicals do not appear to pose a non-carcinogenic risk to e-waste workers through ingestion or dermal contact of bio-accessible fractions of the chemicals. Human biomonitoring campaigns are recommended in the Nigerian e-waste environment considering the elevated concentration levels found for the majority of targeted compounds and that risk parameters required for exposure assessment were only available for a limited number of compounds.