Results from Screening Polyurethane Foam Based Consumer Products for Flame Retardant Chemicals: Assessing Impacts on the Change in the Furniture Flammability Standards

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

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

Children's exposure to brominated flame retardants in the home: The TESIE study

Due to differences in chemical properties and half-lives, best practices for exposure assessment may differ for legacy versus novel brominated flame retardants (BFRs). Our objective was to identify the environment matrix that best predicted biomarkers of children's BFR exposures. Paired samples were collected from children aged 3-6 years and their homes, including dust, a small piece of polyurethane foam from the furniture, and a handwipe and wristband from each child. Biological samples collected included serum, which was analyzed for 11 polybrominated diphenyl ethers (PBDEs), and urine, which was analyzed for tetrabromobenzoic acid (TBBA), a metabolite of 2-ethylhexyl-2,3,4,5-tetrabromobenzoate (EH-TBB). Significant positive correlations were typically observed between BFRs measured in dust, handwipes and wristbands, though wristbands and handwipes tended to be more strongly correlated with one another than with dust. PBDEs, EH-TBB and BEH-TEBP were detected in 30% of the sofa foam samples, suggesting that the foam was treated with PentaBDE or Firemaster® 550/600 (FM 550/600). PBDEs were detected in all serum samples and TBBA was detected in 43% of urine samples. Statistically significant positive correlations were observed between the environmental samples and serum for PBDEs. Urinary TBBA was 6.86 and 6.58 times more likely to be detected among children in the highest tertile of EH-TBB exposure for handwipes and wristbands, respectively (95 % CI: 2.61, 18.06 and 1.43, 30.05 with p < 0.001 and 0.02, respectively). The presence of either PentaBDE or FM 550/600 in furniture was also associated with significantly higher levels of these chemicals in dust, handwipes and serum (for PBDEs) and more frequent detection of TBBA in urine (p = 0.13). Our results suggest that children are exposed to a range of BFRs in the home, some of which likely originate from residential furniture, and that silicone wristbands are a practical tool for evaluating external exposure to both legacy and novel BFRs.

Distribution patterns and origins of organophosphate esters in soils from different climate systems on the Tibetan Plateau

Organophosphate esters (OPEs) are extensively applied in various materials as flame retardants and plasticizers, and have high biological toxicity. OPEs are detected worldwide, even in distant polar regions and the Tibetan Plateau (TP). However, few studies have been performed to evaluate the distribution patterns and origins of OPEs in different climate systems on the TP. This study investigated the distribution characteristics, possible sources, and ecological risks of OPEs in soils from the different climate systems on the TP and its surroundings. The total concentrations of OPEs in soil varied from 468 to 17,451 pg g-1 dry weight, with greater concentrations in southeast Tibet (monsoon zone), followed by Qinghai (transition zone) and, finally, southern Xingjiang (westerly zone). OPE composition profiles also differed among the three areas with tri-n-butyl phosphate dominant in the westerly zone and tris(2-butoxyethyl) phosphate dominant in the Indian monsoon zone. Correlations between different compounds and altitude, soil organic carbon, or longitude varied in different climate zones, indicating that OPE distribution originates from both long-range atmospheric transport and local emissions. Ecological risk assessment showed that tris(2-chloroethyl) phosphate and tri-phenyl phosphate exhibited medium risks in soil at several sites in southeast Tibet. Considering the sensitivity and vulnerability of TP ecosystems to anthropogenic pollutants, the ecological risks potentially caused by OPEs in this region should be further assessed.

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

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

Bioaccumulation and Potential Endocrine Disruption Risk of Legacy and Emerging Organophosphate Esters in Cetaceans from the Northern South China Sea

Despite the increasing health risks shown by the continuous detection of organophosphate esters (OPEs) in biota in recent years, information on the occurrence and potential risks of OPEs in marine mammals remains limited. This study conducted the first investigation into the body burdens and potential risks of 10 traditional OPEs (tOPEs) and five emerging OPEs (eOPEs) in 10 cetacean species (n = 84) from the northern South China Sea (NSCS) during 2005-2021. All OPEs, except for 2-ethylhexyl diphenyl phosphate (EHDPHP), were detected in these cetaceans, indicating their widespread occurrence in the NSCS. Although the levels of the ∑10tOPEs in humpback dolphins remained stable from 2005 to 2021, the concentrations of the ∑5eOPEs showed a significant increase, suggesting a growing demand for these new-generation OPEs in South China. Dolphins in proximity to urban regions generally exhibited higher OPE concentrations than those from rural areas, mirroring the environmental trends of OPEs occurring in this area. All OPE congeners, except for EHDPHP, in humpback dolphins exhibited a maternal transfer ratio >1, indicating that the dolphin placenta may not be an efficient barrier for OPEs. The observed significant correlations between levels of OPEs and hormones (triiodothyronine, thyroxine, and testosterone) in humpback dolphins indicated that OPE exposures might have endocrine disruption effects on the dolphin population.

Co-occurrence of organophosphate diesters and organophosphate triesters in daily household products: Potential emission and possible human health risk

Eight paired organophosphate diesters (Di-OPs) and organophosphate triesters (Tri-OPs) were investigated in wipes from analytical instruments and 47 material samples related to household products, including textiles, electrical/electronic devices, building/ decoration materials and children's products. The total concentrations of Di-OPs ranged in 3577-95551 ng/m2 in the wipes and limit of detection-23002 ng/g in the materials. The Tri-OPs concentrations varied significantly in the ranges of 107218-1756892 ng/m2 and 2.13-503149 ng/g, respectively. Four industrial Di-OPs were detected in > 65% of the studied samples suggesting their direct application in the studied materials. Furthermore, we demonstrated for the first time that four non-industrial Di-OPs, e.g., bis(2-chloroethyl) phosphate, bis(1-chloro-2-propyl) phosphate, bis(1,3-dichloro-2-propyl) phosphate, and bis(butoxyethyl) phosphate, identified as degradation products of their respective Tri-OPs were also detected in these studied samples, which might act as important emission sources of Di-OPs in indoor environments. We estimated the burden of Di-OPs and Tri-OPs in a typical residential house and instrumental room, which both exhibited important contributions from furniture, building and decoration materials, and electrical/electronic devices. Limit health risk was posed to local people via air inhalation.

Trends in flame retardant levels in upholstered furniture and children's consumer products after regulatory action in California

In 2013, California revised its upholstered furniture flammability standard TB 117-2013 to improve fire safety without the need for flame retardant (FR) chemicals. Subsequent legislation (SB 1019) required disclosure of FR content. In 2020 California expanded restriction on FR chemicals to include juvenile products and upholstered furniture (AB 2998). To monitor trends in FR use, and assess the effectiveness of the new regulations, we analyzed 346 samples from upholstered furniture (n = 270) and children's consumer products (n = 76), collected pre- and post-regulatory intervention for added FR chemicals (i.e., ∑FR > 1000 mg/kg). Upholstered furniture samples, collected from products before enactment of the new regulations, had a median FR concentration of 41,600 mg/kg (range: 1360-92,900 mg/kg), with 100% of the foam samples and 13.7% of the textile samples containing ∑FR > 1000 mg/kg. Firemaster formulations (FM 550 and FM 600), a mixture of triphenyl phosphate (TPHP), 2-ethylhexyl-2,3,4,5-tetrabromobenzoate (EH-TBB), bis(2-ethylhexyl)-3,4,5,6-tetrabromophthalate (BEH-TEBP) and a mixture of isopropyl- or tert-butyl-triphenyl phosphates (ITPs or TBPPs), were the most frequently detected FR (34%), followed by tris(1,3-dichloroisopropyl) phosphate (TDCIPP; 25%), TPHP with a mixture of polybrominated diphenyl ethers (BDE-47, 99, 100, 153 and 154; 20%) and tris(2-chloroethyl) phosphate (TCEP; 11%). Upholstered furniture components collected after enactment of the new legislation had a median FR concentration of 2600 mg/kg (range: 1160-49,800 mg/kg, outlier sample 282,200 mg/kg), with 11.9% of the foam samples and no textile samples containing ∑FR > 1000 mg/kg. Of these samples, tris(1-chloro-2-propyl) phosphate (TCIPP) was the most frequently detected FR (55%), followed by TDCIPP (30%) and Firemaster (FM 550, 15%). No PBDEs were detected in the post-regulatory intervention products. Our initial work on children's products showed 15% of the samples contained ∑FR > 1000 mg/kg. In our post- AB 2998 work, no regulated children's product components failed compliance (i.e., ∑FR > 1000 mg/kg). The data confirm successful adoption of the new regulations with most samples in compliance, demonstrating the efficacy of regulatory intervention. Given these results, environmental FR exposure is expected to decrease as older FR treated consumer products are replaced with FR free products.

Toxicity of TPhP on the gills and intestines of zebrafish from the perspectives of histopathology, oxidative stress and immune response

As an organophosphate ester (OPE), triphenyl phosphate (TPhP) has been frequently detected in aquatic environments, and its environmental risk has been widely studied. The gills and intestines are the most important part of the mucosal immune barrier in fish as the first line of defense against the invasion of harmful substances. TPhP is more abundant in the gill and intestine of fish. However, knowledge of the toxic effects and potential mechanisms of TPhP on the intestine and gill is limited. Herein, the adverse effects of TPhP (0.01, 0.1 and 1 mg/L) on the gills and intestines of zebrafish after 75 days of exposure were investigated from the perspectives of histology, oxidative stress and immune level. The histological results of exposed zebrafish showed that TPhP caused significant damage to gills and intestines. TPhP significantly increased the activities of the antioxidant enzymes catalase (CAT) and glutathione s-transferase (GST), inducing oxidative damage to lipids, proteins, and DNA. Meanwhile, the immune function of the gills and intestines was significantly influenced by TPhP, as evidenced by the upregulation of the expression of interleukin-1β (IL-1β) and interleukin-6 (IL-6), upregulation of the content of complement 3 (C3) and complement 4 (C4), and downregulation of the activity of lysozyme (LZM) and the content of immunoglobulin M (IgM). Oxidative stress and the immune response were more severe in the gills. These findings indicate that TPhP, a typical OPE, caused tissue damage in aquatic organisms by inducing oxidative stress and immune damage and has strong environmental toxicity.

Opportunities in Assessing and Regulating Organohalogen Flame Retardants (OFRs) as a Class in Consumer Products

BACKGROUND

In 2015, the U.S. Consumer Product Safety Commission (CPSC) received and then, in 2017, granted a petition under the Federal Hazardous Substances Act to declare certain groups of consumer products as banned hazardous substances if they contain nonpolymeric, additive organohalogen flame retardants (OFRs). The petitioners asked the CPSC to regulate OFRs as a single chemical class with similar health effects. The CPSC later sponsored a National Academy of Sciences, Engineering, and Medicine (NASEM) report in 2019, which ultimately identified 161 OFRs and grouped them into 14 subclasses based on chemical structural similarity. In 2021, a follow-up discussion was held among a group of scientists from both inside and outside of the CPSC for current research on OFRs and to promote collaboration that could increase public awareness of CPSC work and support the class-based approach for the CPSC's required risk assessment of OFRs.

OBJECTIVES

Given the extensive data collected to date, there is a need to synthesize what is known about OFR and how class-based regulations have previously managed this information. This commentary discusses both OFR exposure and OFR toxicity and fills some gaps for OFR exposure that were not within the scope of the NASEM report. The objective of this commentary is therefore to provide an overview of the OFR research presented at SOT 2021, explore opportunities and challenges associated with OFR risk assessment, and inform CPSC's work on an OFR class-based approach.

DISCUSSION

A class-based approach for regulating OFRs can be successful. Expanding the use of read-across and the use of New Approach Methodologies (NAMs) in assessing and regulating existing chemicals was considered as a necessary part of the class-based process. Recommendations for OFR class-based risk assessment include the need to balance fire and chemical safety and to protect vulnerable populations, including children and pregnant women. The authors also suggest the CPSC should consider global, federal, and state OFR regulations. The lack of data or lack of concordance in toxicity data could present significant hurdles for some OFR subclasses. The potential for cumulative risks within or between subclasses, OFR mixtures, and metabolites common to more than one OFR all add extra complexity for class-based risk assessment. This commentary discusses scientific and regulatory challenges for a class-based approach suggested by NASEM. This commentary is offered as a resource for anyone performing class-based assessments and to provide potential collaboration opportunities for OFR stakeholders. https://doi.org/10.1289/EHP12725.

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.

Temporal trends and predictors of gestational exposure to organophosphate ester flame retardants and plasticizers

BACKGROUND

Organophosphate esters (OPEs), used as flame retardants and plasticizers, are chemicals of concern for maternal and infant health. Prior studies examining temporal trends and predictors of OPE exposure are primarily limited by small sample sizes.

OBJECTIVES

Characterize temporal trends and predictors of OPE exposure biomarkers.

METHODS

We determined urinary concentrations of eight biomarkers of OPE exposure at three timepoints during pregnancy for participants in the LIFECODES Fetal Growth Study (n = 900), a nested case-cohort recruited between 2007 and 2018. We examined biomarker concentrations, their variability during pregnancy, and temporal trends over the study period. In addition, we identified sociodemographic and pregnancy characteristics associated with biomarker concentrations. Analyses were conducted using both the within-subject pregnancy geometric means and biomarker concentrations measured at individual study visits.

RESULTS

Five OPE biomarkers were detected in at least 60% of the study participants. Biomarkers were not strongly correlated with one another and intraclass correlation coefficients, measuring within-subject variability during pregnancy, ranged from 0.27 to 0.51. Biomarkers exhibited varying temporal trends across study years. For example, bis(1-chloro-2-propyl) phosphate (BCIPP) increased monotonically, whereas bis(1,3-dichloro-2-propyl) phosphate (BDCIPP) and diphenyl phosphate (DPHP), displayed non-monotonic trends with concentrations that peaked between 2011 and 2014. We observed associations between sociodemographic characteristics and OPE biomarkers. In general, concentrations of most OPE biomarkers were higher among participants from racial and ethnic minority populations, participants who were younger, had higher pre-pregnancy body mass index (BMI), and less than a college degree. We observed consistent results using either averaged or visit-specific biomarker concentrations.

SIGNIFICANCE

We observed widespread exposure to several OPEs and OPE biomarkers displayed varying temporal trends in pregnant people from 2007 to 2018. Concentrations of most OPE biomarkers varied according to sociodemographic factors, suggesting higher burdens of exposure among participants with higher pre-pregnancy BMI, those belonging to racial and ethnic minority populations, and lower educational attainment.

Trends of legacy and emerging organic contaminants in a sediment core from Cienfuegos Bay, Cuba, from 1990 to 2015

Legacy and emerging organic pollutants pose an ever-expanding challenge for the marine environment. This study analysed a dated sediment core from Cienfuegos Bay, Cuba, to assess the occurrence of polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), polybrominated diphenyl ethers (PBDEs), alternative halogenated flame retardants (aHFRs), organophosphate esters (OPEs), and phthalates (PAEs) from 1990 to 2015. The results evidence the continuing presence of historical regulated contaminants (PCBs, OCPs, and PBDEs) in the southern basin of Cienfuegos Bay. PCB contamination declined since 2007, likely in response to the gradual global phasing out of PCB containing materials. There have been relatively consistent low accumulation rates for OCPs and PBDEs at this location (in 2015 approximately 1.9 and 0.26ng/cm²/year, respectively, with 2.8ng/cm²/year for Σ₆PCBs), with indications of recent local DDT use in response to public health emergencies. In contrast, sharp increases are observed between 2012 and 2015 for the contaminants of emerging concern (PAEs, OPEs, and aHFRs), and in the case of two PAEs (DEHP and DnBP) the concentrations were above the established environmental effect limits for sediment dwelling organisms. These increasing trends reflect the growing global usage of both alternative flame retardants and plasticizer additives. Local drivers for these trends include nearby industrial sources such as a plastic recycling plant, multiple urban waste outfalls, and a cement factory. The limited capacity for solid waste management may also contribute to the high concentrations of emerging contaminants, especially plastic additives. For the most recent year (2015), the accumulation rates for Σ₁₇aHFRs, Σ₁₉PAEs, and Σ₁₇OPEs into sediment at this location were estimated to be 10, 46 000, and 750ng/cm²/year, respectively. This data provides an initial survey of emerging organic contaminants within this understudied region of the world. The increasing temporal trends observed for aHFRs, OPEs, and PAEs highlights the need for further research concerning the rapid influx of these emerging contaminants.

Brominated flame retardants and legacy organochlorines in archived human placenta samples: Sex differences, temporal analysis and associations with infant birth weight

Perinatal exposure to persistent organic pollutants (POPs) has been suggested to play a role in the etiology of adverse pregnancy outcomes. This study evaluated temporal changes in the accumulation of several classes of POPs, including polybrominated diphenyl ethers (PBDEs), polychlorinated biphenyls (PCBs) and several organochlorine pesticides in human placenta and examined their associations with birth outcomes at delivery. Placental tissues (n = 99) previously collected and archived at the Duke University Medical Center from 2009 to 2015 were analyzed for 22 POPs using gas chromatography mass spectrometry. The mean age of mothers was 30.6 years; 8% of newborns were characterized as low birthweight (<2500 g). Of the 22 POPs targeted in the analysis, only p,p'-DDE, BDE-47 and BDE-100 were detected in more than 50% of the samples, with median concentrations of 0.110, 0.310, and 0.033 ng/g wet weight, respectively. Placental PBDE concentrations generally decreased over time, particularly BDE-47. Placental tissues associated with female infants had significantly higher levels of BDE-100 than placental tissues associated with male infants (p = 0.02) and a similar, but not statistically significant trend was observed for BDE-47 (p = 0.07). Multivariate regression models revealed that placental BDE-47 concentrations were associated with a significantly lower birthweight among male, but not female infants. A similar, although non-statistically significant, trend was observed for other POPs, further suggesting sex-specific associations between gestational exposure to POPs and birthweight.

Investigating the associations between organophosphate flame retardants (OPFRs) and fine particles in paired indoor and outdoor air: A probabilistic prediction model for deriving OPFRs in indoor environments

Contaminants of emerging concern such as organophosphate flame retardants (OPFRs) are associated with atmospheric fine particles (PM_2.5), which pose the greatest health risk in the world. However, few surveys have explored the interaction between PM_2.5 and OPFRs in residential paired indoor/outdoor environments. 11 priority OPFRs and PM_2.5 were investigated across 178 paired indoor and outdoor air samples taken from 89 children's households in southern Taiwan, across cold and warm seasons. This involved exploring their associations with building characteristics, interior materials, and human activities. We developed a probabilistic predictive model for indoor OPFRs based on the indoor/outdoor (I/O) ratio of contaminants and an air quality index. The significant associations of paired indoor/outdoor OPFRs and PM_2.5 were explored. The indoor level of OPFRs was greater than that of outdoor households, contrasting with PM_2.5. The I/O OPFRs ratio was higher than 1 (except for TEHP, EHDPP, and TCP), which suggests that the sources of OPFRs were primarily emitted from indoors. Indoor TCEP was significantly positively associated with indoor and outdoor PM_2.5. The OPFR level detected in apartments was higher than in houses due to the greater decoration, furniture and electronic devices. However, this was not the case for PM_2.5. TCIPP was the dominant compound in paired indoor and outdoor air. The indoor OPFR predictive model obtained a high accuracy with an R² value of 0.87. The material used in mattresses, the use of purifiers and heaters, and the total material area were the main influencing factors for indoor OPFRs in households. These findings could provide important evidence of the interaction between paired indoor/outdoor OPFRs and PM_2.5 and interior equipment in different building types. In addition, it could prevent the potential risks posed by indoor/outdoor air pollutants and eliminate OPFR emissions through the selection of better construction and building materials.

Flame-Retardant and Smoke-Suppressant Flexible Polyurethane Foams Based on Phosphorus-Containing Polyester Diols and Expandable Graphite

A liquid-phosphorus-containing polyester diol, PPE, was prepared via condensation polymerization using commercial reactive flame retardant 9,10-dihydro-10-[2,3-di(hydroxycarbonyl)propyl]-10-phospha-phenanthrene-10-oxide, adipic acid, ethylene glycol, and 1,4-butanediol. PPE and/or expandable graphite (EG) were then incorporated into phosphorus-containing flame-retardant polyester-based flexible polyurethane foams (P-FPUFs). The structure and properties of the resultant P-FPUFs were characterized using scanning electron microscopy tensile measurements, limiting oxygen index (LOI), vertical burning tests, cone calorimeter tests, thermogravimetric analysis coupled with Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy. Unlike the FPUF prepared using regular polyester polyol (R-FPUF), PPE increased the flexibility and elongation at break of the resultant forms. More importantly, the peak heat release rate (PHRR) and total heat release (THR) of P-FPUF were reduced by 18.6% and 16.3%, respectively, via gas-phase-dominated flame-retardant mechanisms, compared with those of R-FPUF. The addition of EG further reduced the peak smoke production release (PSR) and total smoke production (TSP) of the resultant FPUFs while increasing the LOI and char formation. Interestingly, it was observed that EG noticeably improved the residual quantity of phosphorus in the char residue. When the EG loading was 15 phr, the resulting FPUF (P-FPUF/15EG) attained a high LOI value (29.2%) and exhibited good anti-dripping performance. Meanwhile, the PHRR, THR, and TSP of P-FPUF/15EG were significantly decreased by 82.7%, 40.3%, and 83.4%, respectively, compared with those of P-FPUF. This superior flame-retardant performance can be attributed to the combination of the bi-phase flame-retardant behavior of PPE and condensed-phase flame-retardant characteristics of EG.

Gestational exposure to organophosphate esters and adiposity measures of children up to 6 years: Effect modification by breastfeeding

Organophosphate esters (OPEs) are synthetic chemicals used in various commercial products. Accumulating evidence has shown that they may act as metabolic disruptors. However, no study has investigated the long-term effects of gestational OPEs exposure on childhood adiposity. Breast milk represents the optimal nutritional form of feeding for infants and may protect against the adverse effects of gestational OPEs exposure on offspring development. Using data from the Shanghai-Minhang birth cohort study, we investigated the associations of gestational OPEs exposure with adiposity measures in children up to 6 years of age, and whether breastfeeding could modify these associations. A total of 733 mother-child pairs with available data on OPE concentrations and child anthropometry were included. Eight OPE metabolites were assessed in maternal urine samples collected at 12-16 weeks of pregnancy. Information on children's weight, height, arm circumference, and waist circumference was collected at birth and 0.5, 1, 4, and 6 years of age. Weight-for-age and body mass index-for-age z scores were calculated. The duration of children's breastfeeding was categorized as ≤4 months or >4 months. The generalized estimate equation and Bayesian Kernel Machine Regression models were used to examine the associations of OPEs exposure with children's adiposity measures. Selected OPEs exposure was associated with higher children's adiposity measures. Particularly, we found stronger associations of bis(1-chloro-2-propyl) phosphate (BCIPP), bis(2-chloroethyl) phosphate (BCEP), bis(1,3-dichloro-2-propyl) phosphate (BDCPP), and di-o-cresyl phosphate and di-p-cresyl phosphate (DCP) with higher adiposity measures in children breastfed for ≤4 months, while little evidence of associations was found among those breastfed for >4 months. Our study suggested that gestational OPEs exposure could alter children's adiposity measures, but the potential effects were attenuated if children were breastfed for >4 months.

Chlorinated organophosphate esters in Irish waste foams and fabrics: Concentrations, preliminary assessment of temporal trends and evaluation of the impact of a concentration limit value

Concentrations of the chlorinated organophosphate esters (Cl-OPEs): tris(2-chloroethyl) phosphate (TCEP), tris(1-chloro-2-propyl) phosphate (TCIPP), and tris(1,3-dichloro-2-propyl) phosphate (TDCIPP) were measured in 273 waste synthetic foam and fabric articles collected in Ireland between 2019 and 2020. Articles examined comprised: polystyrene building insulation foam, as well as foam fillings and fabric coverings from furniture, mattresses, end-of-life vehicles, curtains, and carpets. Cl-OPEs were also measured in 156 samples from the same categories (except for building insulation foam) collected in 2015-16. Concentrations of TCIPP and TDCIPP in most samples exceeded those of TCEP; with those of TCIPP and TDCIPP generally and for some waste categories significantly (p < 0.05) higher in samples collected in 2019-20. Given potential future restrictions on use of these Cl-OPEs, we identified articles containing concentrations that exceeded 1000 mg/kg, in line with a similar limit that at the time of sample collection existed for some brominated flame retardants within the European Union. In 2019-20, 82 articles contained at least one Cl-OPE above 1000 mg/kg, with at least one article exceeding this concentration in each waste category examined. By comparison, only 28 samples collected in 2015-16, contained at least one Cl-OPE >1000 mg/kg, and articles exceeding this concentration were restricted to furniture and mattress foam, along with foams and fabrics from end-of-life vehicles. In the event of the introduction of such a limit on Cl-OPE concentrations in waste, it will result in 7200 t/year of such waste (24 % of the total) being rendered unrecyclable, while removing 98 % of the estimated ∼147,000 kg/year of Cl-OPEs from the recycling stream.

Elevated concentrations of halogenated flame retardants in waste childcare articles from Ireland

Concentrations of legacy and alternative halogenated flame retardants (HFRs) including chlorinated organophosphate esters (Cl-OPEs), were measured in waste childcare articles (n = 275 for Cl-OPEs, n = 187 for other HFRs) from the Republic of Ireland between 2019 and 2020. Articles studied comprised foams and fabrics from: child car seats, cot mattresses, changing mats, pushchairs, prams, and related items. Fifteen articles (7.7%) exceeded the European Union limit value of 1000 mg/kg for polybrominated diphenyl ethers (PBDEs) (all due to BDE-209), an additional 15 exceeded the limit for hexabromocyclododecane (HBCDD), with 7 articles exceeding the limit for both PBDEs and HBCDD. An even greater proportion of articles contained concentrations exceeding 1000 mg/kg for: tris(1-chloro-2-propyl) phosphate (TCIPP) (n = 73, 27%) and tris(1,3-dichloro-2-propyl) phosphate (TDCIPP) (n = 58, 21%), with concentrations greater than 1000 mg/kg also observed for: tris(2-chloroethyl) phosphate (TCEP) (n = 14, 5.1% articles), 2-ethylhexyl tetrabromobenzoate (EH-TBB) (n = 7, 3.7%), decabromodiphenyl ethane (DBDPE), and bis(2-ethylhexyl)tetrabromophthalate (BEH-TEBP) (both n = 5, 2.7%). Overall, 120 samples contained at least one HFR at a concentration exceeding 1000 mg/kg. In addition to the waste management implications of our findings, our data raise concerns about child exposure to HFRs during the use phase of these everyday items.

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.

Chlorinated Organophosphate Flame Retardants Impair the Lung Function via the IL-6/JAK/STAT Signaling Pathway

Toxicological studies have revealed the adverse impacts of organophosphate flame retardants (OPFRs) on the respiratory system, while there is a lack of epidemiological evidence, and information for risk assessment remains insufficient. Herein, we investigated the associations of urinary metabolites of OPFRs with the lung function in 987 adults participating in the U.S. National Health and Nutrition Examination Survey 2011-2012. The elevation of three primary metabolites of chlorinated OPFRs [bis(1,3-dichloro-2-propyl) phosphate (BDCIPP), bis(2-chloroethyl) phosphate (BCEP), and bis(1-chloro-2-propyl) phosphate (BCIPP)] was related to pulmonary dysfunction in a sample-weighted regression model. Each one-unit increase in the log-transformed levels of BDCIPP and BCEP was related to 91.52 and 79.34 mL reductions in the forced vital capacity (FVC). Each one-unit elevation in BCIPP was correlated with 130.86, 153.56, 302.26, and 148.24 mL reductions in forced expiratory volume 1st second (FEV₁), FVC, peak expiratory flow rate (PEF), and forced expiratory flow at 25-75% of FVC (FEF_25-75%), respectively. Then, an adverse outcome pathway (AOP) framework was constructed using the Comparative Toxicogenomics Database, the Toxicity Forecaster, and the GeneCards database. Based on the weight of the evidence, BDCIPP, BCEP, BCIPP, and their parent compounds (TDCIPP, TCEP, and TCIPP) may affect the IL-6/Janus kinase/signal transducer and activator of transcription (JAK/STAT) pathway, induce airway remodeling, and impair the lung function. Additionally, tobacco smoke exposure may modify the effects of BDCIPP on the lung function (P_int < 0.05) and affect the IL-6-mediated AOP. These results suggested that chlorinated OPFRs were associated with pulmonary dysfunction via the IL-6/JAK/STAT pathway.

Occurrence and risk assessment of organophosphate esters and bisphenols in San Francisco Bay, California, USA

Organophosphate esters (OPEs) and bisphenols are two classes of industrial chemicals that are ubiquitously detected in environmental matrices due to high global production and widespread use, particularly in the manufacture of plastic products. In 2017, water samples collected throughout the highly urbanized San Francisco Bay were analyzed for 22 OPEs and 16 bisphenols using liquid chromatography-electrospray ionization-Q Trap-mass spectrometry. Fifteen of the 22 OPEs were detected, with highest median concentrations in the order TCPP (42 ng/L) > TPhP (9.5 ng/L) > TBOEP (7.6 ng/L) > TnBP (7.5 ng/L) > TEP (6.7 ng/L) > TDCIPP (6.2 ng/L). In contrast, only two of 16 bisphenols, BPA and BPS, were quantified, with concentrations ranging from <0.7-35 ng/L and <1-120 ng/L, respectively. BPA and a few OPEs (EHDPP and TEHP) were primarily present in the particulate phase, while BPS and all other observed OPEs were predominantly found in the dissolved phase. Pairwise correlation analysis revealed several strong, positive correlations among OPEs, and few weak, negative correlations between OPEs and BPA, suggesting differences between the two classes with respect to their sources, pathways, and/or fate in the environment. Concentrations of OPEs and bisphenols observed in this study were generally consistent with reported concentrations in other estuarine and marine settings globally. TDCIPP exceeded existing predicted no-effect concentrations (PNECs) at some sites, and six other compounds (TCrP, IDDPP, EHDPP, TPhP, TBOEP, and BPA) were observed at levels approaching individual compound PNECs (not considering mixture effects), indicating potential risks to Bay biota. These results emphasize the need to control releases of these contaminants in order to protect the ecosystem. Periodic monitoring can be used to maintain vigilance in the face of potential regrettable substitutions.

High-Resolution Mass Spectrometry Screening of Emerging Organophosphate Esters (OPEs) in Wild Fish: Occurrence, Species-Specific Difference, and Tissue-Specific Distribution

There is a dearth of information regarding the pollution status of emerging organophosphate esters (OPEs) in wild fish. Here, we optimized and validated a quick, easy, cheap, effective, rugged, and safe (QuEChERS) pretreatment method, which was further applied for target, suspect, and nontarget screening of OPEs in n = 48 samples of wild fishes from Taihu Lake (eastern China). This integrated technique allows us to fully identify 20 OPEs, and 9 out of them are emerging OPEs detected in wild fish for the first time. Importantly, some of the emerging OPEs, i.e., tris(2,4-di-tert-butylphenyl) phosphate (TDtBPP), 4-tert-butylphenyl diphenyl phosphate (BPDP), and 2-isopropylphenyl diphenyl phosphate (IPDP), exhibited greater or at least comparable contamination levels as compared to traditional ones. There were no statistically significant interspecies (n = 6) differences regarding OPE concentrations. However, we observed significant differences on OPE concentrations among different tissues of silver carp (Hypophthalmichthys molitrix), for which the intestine has the highest OPE mean concentration (46.5 ng/g wet weight (ww)), followed by the liver (20.1 ng/g ww) ≈ brain (20.0 ng/g ww) > gill (14.8 ng/g ww) > muscle (11.4 ng/g ww). An interesting exception is IPDP, which presents an unexpectedly high concentration in the brain (0.510 ng/g ww). Collectively, this study expands our understanding of OPE contamination in wild fish and clearly shows that emerging TDtBPP, IPDP, and BPDP could play an equally important role as traditional OPEs in contribution of OPE pollution in wild fish samples.

Comparison of the mechanisms of estrogen disrupting effects between triphenyl phosphate (TPhP) and tris(1,3-dichloro-2-propyl) phosphate (TDCIPP)

As the typical aryl-organophosphate flame retardants (OPFRs), triphenyl phosphate (TPhP) and tris(1,3-dichloro-2-propyl) phosphate (TDCIPP) were reported to be estrogen disruptors. However, estrogen receptor α (ERα) binding experiments could not explain their biological effects. In this study, their action on ERα, G protein-coupled estrogen receptor (GPER) and the synthesis of 17β-estradiol (E2) were investigated using in vitro assays and molecular docking. The results showed that TPhP acted as an ERα agonist and recruited steroid receptor co-activator 1 (SRC1) and 3 (SRC3), which was found for the first time. Unlike TPhP, TDCIPP acted as an ERα antagonist. However, both TPhP and TDCIPP activated the estrogen pathway by GPER in SKBR3 cells which were lack of ERα. Although molecular docking results revealed that both TPhP and TDCIPP could dock into ERα and GPER, their substituent groups and combination mode might affect the receptor activation. In addition, by using estrogen biosynthesis assay in H295R cells, both of TPhP and TDCIPP were found to promote E2 synthesis and E2/T ratio involving their different alteration on levels of progesterone, testosterone and estrone, and expression of various key genes. Our data proposed estrogen-disrupting mechanism frameworks of TPhP and TDCIPP. Moreover, our results will contribute to future construction of adverse outcome pathway (AOP) framework of endocrine disruptors.

Green, tough and highly efficient flame-retardant rigid polyurethane foam enabled by double network hydrogel coatings

Designing eco-friendly fireproof rigid polyurethane foam (RPUF) that can completely stop fire ignition or spread has significant technological implications, which has been proved to be extremely challenging. Herein, a novel green strategy based on double network hydrogel coating was developed to enhance the flame retardancy of RPUF via a facile casting and curing process. This strategy can create a homogeneous hydrogel fire-resistant layer with strong adhesion on the outermost surface of the substrate. Due to good water holding capacity and excellent thermal management properties, the hydrogel coating showed excellent fire retardancy. As a proof-of-concept, polyacrylic-polydopamine (PAAm-PDA) double network hydrogel coating was applied to an extremely flammable RPUF substrate. Compared with the neat foam, the PAAm-PDA coated RPUF exhibited an overall improvement in fire-safety performance, including a rapid self-quenching behavior, a six-fold enhancement in time to ignition (TTI), and 39.7% and 42.2% decreases in the mean heat release rate (HRR) and total smoke production (TSP), respectively. Furthermore, the tough hydrogel-coated RPUF possessed enough mechanical properties to meet the requirement of its practical applications. Benefiting from its low cost, easy-to-process and eco-friendly characteristics, this hydrogel fireproof coating strategy provides a new direction for developing green and safe structural materials with widespread use.

Chemical contaminant exposures assessed using silicone wristbands among occupants in office buildings in the USA, UK, China, and India

Little is known about chemical contaminant exposures of office workers in buildings globally. Complex mixtures of harmful chemicals accumulate indoors from building materials, building maintenance, personal products, and outdoor pollution. We evaluated exposures to 99 chemicals in urban office buildings in the USA, UK, China, and India using silicone wristbands worn by 251 participants while they were at work. Here, we report concentrations of polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs) and other brominated flame retardants (BFRs), organophosphate esters (OPEs), phthalates and phthalate alternatives, pesticides, and polycyclic aromatic hydrocarbons (PAHs). First, we found major differences in office worker chemical exposures by country, some of which can be explained by regulations and use patterns. For example, exposures to several pesticides were substantially higher in India where there were fewer restrictions and unique malaria challenges, and exposures to flame retardants tended to be higher in the USA and UK where there were historic, stringent furniture flammability standards. Higher exposures to PAHs in China and India could be due to high levels of outdoor air pollution that penetrates indoors. Second, some office workers were still exposed to legacy PCBs, PBDEs, and pesticides, even decades after bans or phase-outs. Third, we identified exposure to a contemporary PCB that is not covered under legacy PCB bans due to its presence as an unintentional byproduct in materials. Fourth, exposures to novel BFRs, OPEs, and other chemicals commonly used as substitutes to previously phased-out chemicals were ubiquitous. Fifth, some exposures were influenced by individual factors, not just countries and buildings. Phthalate exposures, for example, were related to personal care product use, country restrictions, and building materials. Overall, we found substantial country differences in chemical exposures and continued exposures to legacy phased-out chemicals and their substitutes in buildings. These findings warrant further research on the role of chemicals in office buildings on worker health.

Modeling of Flame Retardants in Typical Urban Indoor Environments in China during 2010-2030: Influence of Policy and Decoration and Implications for Human Exposure

Novel flame retardants (FRs) are of increasing concern, given growing evidence of health effects and use to replace polybrominated diphenyl ethers (PBDEs). This study modeled combined effects of use policies and decoration on indoor FRs and human exposure for 18 widely used PBDEs, organophosphate esters (OPEs), and novel brominated flame retardants in typical urban indoor environments in China. The current estimated indoor emission rates and average concentrations in air and dust of the 18 FRs were 10²-10³ ng/h, 561 ng/m³, and 1.5 × 10⁴ ng/g, respectively, with seven OPEs dominant (>69%). Different use patterns exist between China and the US and Europe. Scenarios modeled over 2010-2030 suggested that decoration would affect indoor concentrations of FRs more than use policies, and use policies were mainly responsible for shifts of FR composition. Additional use of hexabromobenzene and 2,3,4,5,6-pentabromotoluene and removal of BDE-209 would make the total human exposure to the modeled FR mixture increase after the restriction of penta- and octa-BDE but decrease after deca-BDE was banned. Better knowledge of the toxicity of substitutes is needed for a complete understanding of the health implications of such changes. Toddlers may be more affected by use changes than adults. Such studies are supportive to the management of FR use.

Probing Legacy and Alternative Flame Retardants in the Air of Chinese Cities

An increasing number of alternative flame retardants (FRs) are being introduced, following the international bans on the use of polybrominated diphenyl ether (PBDE) commercial mixtures. FRs' production capacity has shifted from developed countries to developing countries, with China being the world's largest producer and consumer of FRs. These chemicals are also imported with e-waste to China. Therefore, it is important to understand the current status of regulated brominated FRs, their phase-out in China, and their replacement by alternatives. In this study, a broad suite of legacy and alternative FRs, including eight PBDEs, six novel brominated FRs (NBFRs), two dechlorane plus variants (DP_S), and 12 organophosphate FRs (OPFRs) were evaluated in the air of 10 large Chinese cities in 2018. OPFRs are the most prevalent FRs in China, exhibiting a wide range of 1-612 ng/m³, which is several orders of magnitude higher than PBDEs (1-1827 pg/m³) and NBFRs (1-1428 pg/m³). BDE 209 and DBDPE are the most abundant compounds in brominated FRs (>80%). The North China Plain (NCP, excluding Beijing), Guangzhou, and Lanzhou appear to be three hotspots, although with different FR patterns. From 2013/2014 to 2018, levels of PBDEs, NBFRs, and DPs have significantly decreased, while that of OPFRs has increased by 1 order of magnitude. Gas-particle partitioning analysis showed that FRs could have not reached equilibrium, and the steady-state model is better suited for FRs with a higher log K_OA (>13). To facilitate a more accurate FR assessment in fine particles, we suggest that, in addition to the conventional volumetric concentration (pg/m³), the mass-normalized concentration (pg/g PM_2.5) could also be used.

Organophosphite Antioxidants in Mulch Films Are Important Sources of Organophosphate Pollutants in Farmlands

Organophosphite antioxidants (OPAs) are important auxiliary antioxidants used in plastic polymers and can be oxidized to organophosphate esters (OPEs) during production and processing. In this work, the occurrence of OPAs and OPEs in farmlands with or without mulch film applications was investigated. Six OPAs and five OPEs were detected, with the median concentrations of 2.66 ng/g (∑₆OPAs) and 100 ng/g (∑₅OPEs) in the film-mulching soil and 1.16 ng/g (∑₆OPAs) and 47.9 ng/g (∑₅OPEs) in the nonfilm-mulching soil, respectively. The oxidative derivative of AO168 (tris (2,4-di-tert-butylphenyl) phosphite), a typical OPA, AO168═O (tris (2,4-di-tert-butylphenyl) phosphate) was frequently detected in farmlands at the concentrations of 0-731 ng/g, which is much higher than that of the commercial OPEs (0-12.1 ng/g). This suggests that the oxidation derivatives of OPAs (OPAs═O) might be important OPE contaminants in soils. Mulch films could be their important source. According to the simulation migration experiment, the emission risk ranges of AO168 and AO168═O from mulch films to soils in China were estimated to be 3.96-87.6 and 10.5-95.3 tons/year, respectively, which were much higher than those of OPEs from sewage sludge applications. Simulation experiments also demonstrated that oxidation was the major pathway for OPAs in soils. OPAs with small substituent groups could be potential sources for organophosphate diesters. For the first time, the serious pollution of OPAs and OPAs═O in soils has been reported, and mulch films have been identified as their potential source.

Impact of "healthier" materials interventions on dust concentrations of per- and polyfluoroalkyl substances, polybrominated diphenyl ethers, and organophosphate esters

Per- and polyfluoroalkyl substances (PFAS), polybrominated diphenyl ethers (PBDEs), and organophosphate esters (OPEs) are found in building materials and associated with thyroid disease, infertility, and impaired development. This study's objectives were to (1) compare levels of PFAS, PBDEs, and OPEs in dust from spaces with conventional versus "healthier" furniture and carpet, and (2) identify other product sources of flame retardants in situ. We measured 15 PFAS, 8 PBDEs, and 19 OPEs in dust from offices, common areas, and classrooms having undergone either no intervention (conventional rooms in older buildings meeting strict fire codes; n = 12), full "healthier" materials interventions (rooms with "healthier" materials in buildings constructed more recently or gut-renovated; n = 7), or partial interventions (other rooms with at least "healthier" foam furniture but more potential building contamination; n = 28). We also scanned all materials for bromine and phosphorus as surrogates of PBDEs and OPEs respectively, using x-ray fluorescence. In multilevel regression models, rooms with full "healthier" materials interventions had 78% lower dust levels of PFAS than rooms with no intervention (p < 0.01). Rooms with full "healthier" interventions also had 65% lower OPE levels in dust than rooms with no intervention (p < 0.01) and 45% lower PBDEs than rooms with only partial interventions (p < 0.10), adjusted for covariates related to insulation, electronics, and furniture. Bromine loadings from electronics in rooms were associated with PBDE concentrations in dust (p < 0.05), and the presence of exposed insulation was associated with OPE dust concentrations (p < 0.001). Full "healthier" materials renovations successfully reduced chemical classes in dust. Future interventions should address electronics, insulation, and building cross-contamination.

Assessing Indoor Dust Interference with Human Nuclear Hormone Receptors in Cell-Based Luciferase Reporter Assays

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS), organophosphate esters (OPEs), and polybrominated diphenyl ethers (PBDEs) are hormone-disrupting chemicals that migrate from building materials into air and dust.

OBJECTIVES

We aimed to quantify the hormonal activities of 46 dust samples and identify chemicals driving the observed activities.

METHODS

We evaluated associations between hormonal activities of extracted dust in five cell-based luciferase reporter assays and dust concentrations of 42 measured PFAS, OPEs, and PBDEs, transformed as either raw or potency-weighted concentrations based on Tox21 high-throughput screening data.

RESULTS

All dust samples were hormonally active, showing antagonistic activity toward peroxisome proliferator-activated receptor (PPARγ2) (100%; 46 of 46 samples), thyroid hormone receptor (TRβ) (89%; 41 samples), and androgen receptor (AR) (87%; 40 samples); agonist activity on estrogen receptor (ERα) (96%; 44 samples); and binding competition with thyroxine (T4) on serum transporter transthyretin (TTR) (98%; 45 samples). Effects were observed with as little as 4μg of extracted dust. In regression models for each chemical class, interquartile range increases in potency-weighted or unknown-potency chemical concentrations were associated with higher hormonal activities of dust extracts (potency-weighted: ΣPFAS-TRβ, ↑28%, p<0.05; ΣOPEs-TRβ, ↑27%, p=0.08; ΣPBDEs-TRβ, ↑20%, p<0.05; ΣPBDEs-ERα, ↑7.7%, p=0.08; unknown-potency: ΣOPEs-TTR, ↑34%, p<0.05; ΣOPEs-AR, ↑13%, p=0.06), adjusted for chemicals with active, inactive, and unknown Tox21 designations.

DISCUSSION

All indoor dust samples exhibited hormonal activities, which were associated with PFAS, PBDE, and OPE levels. Reporter gene cell-based assays are relatively inexpensive, health-relevant evaluations of toxic loads of chemical mixtures that building occupants are exposed to. https://doi.org/10.1289/EHP8054.

A review of organophosphate esters in indoor dust, air, hand wipes and silicone wristbands: Implications for human exposure

The ubiquity of organophosphate esters (OPEs) in various environmental matrices inevitably pose human exposure risks. Numerous studies have investigated human exposure pathways to OPEs, including air inhalation, dust ingestion, dermal contact, and dietary and drinking water intake, and have indicated that indoor dust and indoor air routes are frequently the two main human exposure pathways. This article reviews the literature on OPE contamination in indoor air and dust from various microenvironments and on OPE particle size distributions and bioavailability in dust conducted over the past 10 years. Ways in which sampling strategies are related to the uncertainty of exposure assessment results and comparability among different studies in terms of sampling tools, sampling sites, and sample types are addressed. Also, the associations of OPEs in indoor dust/air with human biological samples were summarized. Studies on two emerging matrices, hand wipes and silicone wristbands, are demonstrated to be more comprehensive and accurate in reflecting personal human exposure to OPEs in microenvironments and are summarized. Given the direct application of some diester OPEs (di-OPEs) in numerous products, research on their existence in indoor dust and food and on their effects on human urine are also discussed. Finally, related research trends and avenues for future research are prospected.

Atmospheric organophosphate esters in the Western Antarctic Peninsula over 2014-2018: Occurrence, temporal trend and source implication

Organophosphate esters (OPEs) were comprehensively investigated in the air samples collected using high-volume samplers near the Chinese Great Wall Station in the Western Antarctic Peninsula over the period of 2014-2018. The concentrations of ∑₈OPEs (gaseous + particle phases) ranged from 33.9 to 404 pg/m³ with a geometric mean of 119 ± 12.0 pg/m³. Tris [(2R)-1-chloro-2-propyl] phosphate (TCIPP) and tris(2-chloroethyl) phosphate (TCEP) dominated in the gaseous phase, while tris-n-butyl phosphate (TnBP) was the most abundant OPEs in the particle phase, followed by TCIPP and TCEP. An apparently temporal trend was observed for atmospheric ∑₈OPEs over the five years, with a doubling time of about 3.8 years, which indicated continuous inputs of OPEs into the sampling area. The particle-bound ∑₈OPEs accounted for 45% of the total, generally lower than that reported in the Arctic. Gas-particle partitioning modeling suggested that the partitioning of OPEs with higher logK_OA values approached the steady state in the Antarctic air. The back-trajectory modeling showed that high levels of OPEs were usually associated with air inputs from the northwest of the peninsula. This suggested that long-range transport from South America, which was confirmed by the no temperature dependencies of OPEs concentrations (excluding TnBP). Nevertheless, a steady high level of particle-bound TnBP implied local sources in the Western Antarctic Peninsula, which required further investigation in future works.

Organophosphate Diesters (Di-OPEs) Play a Critical Role in Understanding Global Organophosphate Esters (OPEs) in Fishmeal

Organophosphate triesters (tri-OPEs) have recently been widely identified in aquatic ecosystems, but information on their organophosphate diester (di-OPE) metabolites is sparsely available. Herein, uniform fishmeal products were collected across the globe (the U.S., China, Europe, South America, and Southeast Asia). Sixteen representative tri-OPEs and eight di-OPEs were investigated to reveal whether industrial production, metabolism, environmental persistence, or physicochemical properties are the key factors influencing their environmental burden and distribution. Tri-OPEs and di-OPEs were 100% detected in fishmeal, with bis(2-chloroethyl) hydrogen phosphate (BCEP) and bis(1,3-dichloro-2-propyl) phosphate (BDCIPP) at discernible levels in marine fauna for the first time. Average concentration of di-OPEs (49.6 ± 27.5 ng/g dw) was of the same order of magnitude as that of tri-OPEs (59.3 ± 92.2 ng/g dw). Geographical-specific distributions of tris(2-chloroethyl) phosphate (TCEP), tris(2-chloroisopropyl) phosphate (TCIPP), triphenyl phosphate (TPhP), tris(2-butoxyethyl) phosphate (TBOEP), and 2-ethylhexyl diphenyl phosphate (EHDPP) were statistically significant (p < 0.05). Mean concentration ratios ranged from 0.087 for the BCEP-TCEP pair to 507 for the dimethyl phosphate (DMP)-trimethyl phosphate (TMP) pair. Only the TPhP-diphenyl phosphate (DPhP) pair presented a strong positive linear correlation (r = 0.731; p < 0.01), and DPhP was proved a degradation origin. Commercial sources had a significant overall impact on distribution patterns of the DMP-TMP and the dibutyl phosphate (DnBP) - tri-n-butyl phosphate (TnBP) pairs, whereas biotic transformation and abiotic stability profoundly influenced the bis(2-ethylhexyl) phosphate (BEHP)-tris(2-ethylhexyl) phosphate (TEHP), the bis(1-chloro-2-propyl) phosphate (BCIPP)-TCIPP, and the BCEP-TCEP pairs. Di-OPEs are critical to understand environmental behavior of tri-OPEs in marine fauna.

Young infants' exposure to organophosphate esters: Breast milk as a potential source of exposure

Organophosphate esters (OPEs) are applied as both flame retardants and plasticizers to a variety of consumer items such as home furnishings, construction materials, and children's products. While some assessments have characterized exposure among toddlers and young children, little is known about the OPE exposure among infants, who are a vulnerable population due to their rapid development. Here, we collected spot urine samples from 6-week-old (n = 100) and 12-month-old infants (n = 63), with about half of the infants evaluated at both ages (n = 52), to characterize OPE exposure and determine what factors contributed to higher exposures. Five of six OPE metabolites analyzed were detected frequently (>70%). Diphenyl phosphate was detected in every urine sample, while bis(2-chloro-isopropyl) phosphate (BCIPP) was the most abundant metabolite measured overall. Concentrations of bis(1-chloro-2-propyl) 1-hydroxy-2-propyl phosphate (BCIPHIPP) and BCIPP [i.e., metabolites of tris(2-chloro-isopropyl) phosphate (TCIPP)] were significantly greater among 6-week-old infants compared to 12-month-olds, while levels of other OPE metabolites were not statistically different in the first year of life. OPE metabolites were generally correlated with one another in samples collected at each age (r_s = 0.25-0.75; p < 0.05), and except BCIPHIPP, concentrations of the same metabolite were correlated over time (r_s = 0.41-0.53; p < 0.05). Breastfeeding at 6 weeks of age and owning a larger number of children's products were associated with increased concentrations of urinary BDCIPP. Infants who were currently receiving breast milk had higher levels of TCIPP metabolites; urinary BCIPP concentrations were 6.2 times higher in infants receiving breast milk at 6 weeks of age, and BCIPHIPP levels were 2.2 times higher for 12-month-old infants receiving breast milk (10^β = 7.2; 95% CI: 1.6-32.1 and 10^β = 3.2; 95% CI: 1.2-8.1, respectively). Differences in the predominant TCIPP metabolite associated with breastfeeding may suggest differences in metabolism with age. Cumulatively, our results suggest levels of OPE exposure may be higher for infants than other age groups, including toddlers and older children.

Occurrence and partitioning of brominated flame retardants (BFRs) in indoor air and dust: a 15-month case study in a test home

Ten polybrominated diphenyl ethers (PBDEs) and 16 novel brominated flame retardants (NBFRs) were measured in air and dust samples collected in a test home in Harbin, China, from January 2017 to June 2018. The PBDE and NBFR concentrations in indoor air were in the ranges of 0.598-14.5 pg m^-3 and 9.28-686 pg m^-3, respectively. The ranges of the PBDE and NBFR concentrations in indoor dust were 221-1060 ng g^-1 and 71.9-1160 ng g^-1, respectively. Brominated flame retardant (BFR) concentrations in indoor air were affected by the temperature, relative humidity (RH), and ventilation. The BFR concentrations in indoor dust did not show temperature dependence. All dust samples were sieved into 6 size fractions (F1-F6: 1000-2000 μm, 500-1000 μm, 250-500 μm, 125-250 μm, 63-125 μm, and < 63 μm). The mass percentage of BFRs in F6 was the highest. The BFR concentrations did not increase constantly with a particle size decrease, and the concentrations in F2 were higher than those in F3. The partitioning behavior of BFRs illustrates that the dust-air partitioning coefficient approximately approached equilibrium within F5, F6, and the total dust fraction (FA) in the test home when logK_OA was between 9.1 and 11.32. Air-dust fugacity fractions were calculated, and the results suggested that most of the BFRs were mainly transferred from air to dust in the indoor environment for F1-F6.

Review of emerging contaminant tris(1,3-dichloro-2-propyl)phosphate: Environmental occurrence, exposure, and risks to organisms and human health

Tris(1,3-dichloro-2-propyl)phosphate (TDCPP) is a halogen-containing organophosphorus chemical that is widely employed in various consumer products with a high production volume. As an additive flame retardant (FR), TDCPP tends to be released into the environment through multiple routes. It is ubiquitous in environmental media, biotic matrixes, and humans, and thus is deemed to be an emerging environmental contaminant. To date, significant levels of TDCPP and its primary diester metabolite, bis(1,3-dichloro-2-propyl)phosphate, have been detected in human samples of seminal plasma, breast milk, blood plasma, placenta, and urine, thereby causing wide concern about the potential human health effects resulting from exposure to this chemical. Despite the progress in research on TDCPP over the past few years, we are still far from fully understanding the environmental behavior and health risks of this emerging contaminant. Thus, this paper critically reviews the environmental occurrence, exposure, and risks posed by TDCPP to organisms and human health among the literature published in the last decade. It has been demonstrated that TDCPP induces acute-, nerve-, developmental-, reproductive-, hepatic-, nephron-, and endocrine-disrupting toxicity in animals, which has caused increasing concern worldwide. Simultaneously, TDCPP induces cytotoxicity by increasing the formation of reactive oxygen species and inducing endoplasmic reticulum stress in multiple human cell lines in vitro, and also causes endocrine-disrupting effects, including reproductive dysfunction and adverse pregnancy outcomes, according to human epidemiology studies. This review not only provides a better understanding of the behavior of this emerging contaminant in the environment, but also enhances the comprehension of the health risks posed by TDCPP exposure to ecosystems and humans.

Maternal urinary concentrations of organophosphate ester metabolites: associations with gestational weight gain, early life anthropometry, and infant eating behaviors among mothers-infant pairs in Rhode Island

BACKGROUND

Organophosphate esters (OPEs)-used as flame retardants and plasticizers-are associated with adverse pregnancy outcomes such as reduced fecundity and live births and increased preterm delivery. OPEs may interfere with growth and metabolism via endocrine-disruption, but few studies have investigated endocrine-related outcomes. The objective of this pilot study (n = 56 mother-infant pairs) was to evaluate associations of OPEs with gestational weight gain (GWG), gestational age at delivery, infant anthropometry, and infant feeding behaviors.

METHODS

We quantified OPE metabolites (bis-2-chloroethyl phosphate [BCEP], bis (1,3-dichloro-2-propyl) phosphate [BDCPP], diphenyl phosphate [DPHP]) in pooled maternal spot urine collected throughout pregnancy (~ 12, 28, and 35 weeks' gestation). We obtained maternal sociodemographic characteristics from questionnaires administered at enrollment and perinatal characteristics from medical record abstraction. Trained research assistants measured infant weight, length, head and abdominal circumferences, and skinfold thicknesses at birth and 6 weeks postpartum. Mothers reported infant feeding behavior via the Baby Eating Behavior Questionnaire (BEBQ). Using multiple linear regression, we assessed associations of log2-transformed maternal urinary OPE metabolites with GWG, gestational age at delivery, infant anthropometry at birth, weekly growth rate, and BEBQ scores at 6 weeks postpartum. We used linear mixed effects (LME) models to analyze overall infant anthropometry during the first 6 weeks of life. Additionally, we considered effect modification by infant sex.

RESULTS

We observed weak positive associations between all OPE metabolites and GWG. In LME models, BDCPP was associated with increased infant length (β = 0.44 cm, 95%CI = 0.01, 0.87) and weight in males (β = 0.14 kg, 95%CI = 0.03, 0.24). BDCPP was also associated with increased food responsiveness (β = 0.23, 95%CI = 0.06, 0.40). DPHP was inversely associated with infant abdominal circumference (β = - 0.50 cm, 95%CI = - 0.86, - 0.14) and female weight (β = - 0.19 kg, 95%CI = - 0.36, - 0.02), but positively associated with weekly growth in iliac skinfold thickness (β = 0.10 mm/wk., 95%CI = 0.02, 0.19). Further, DPHP was weakly associated with increased feeding speed. BCEP was associated with greater infant thigh skinfold thickness (β = 0.34 mm, 95%CI = 0.16, 0.52) and subscapular skinfold thickness in males (β = 0.14 mm, 95%CI = 0.002, 0.28).

CONCLUSIONS

Collectively, these findings suggest that select OPEs may affect infant anthropometry and feeding behavior, with the most compelling evidence for BDCPP and DPHP.

The multi-dimensional embryonic zebrafish platform predicts flame retardant bioactivity

Flame retardant chemicals (FRCs) commonly added to many consumer products present a human exposure burden associated with adverse health effects. Under pressure from consumers, FRC manufacturers have adopted some purportedly safer replacements for first-generation brominated diphenyl ethers (BDEs). In contrast, second and third-generation organophosphates and other alternative chemistries have limited bioactivity data available to estimate their hazard potential. In order to evaluate the toxicity of existing and potential replacement FRCs, we need efficient screening methods. We built a 61-FRC library in which we systemically assessed developmental toxicity and potential neurotoxicity effects in the embryonic zebrafish model. Data were compared to publicly available data generated in a battery of cell-based in vitro assays from ToxCast, Tox21, and other alternative models. Of the 61 FRCs, 19 of 45 that were tested in the ToxCast assays were bioactive in our zebrafish model. The zebrafish assays detected bioactivity for 10 of the 12 previously classified developmental neurotoxic FRCs. Developmental zebrafish were sufficiently sensitive at detecting FRC structure-bioactivity impacts that we were able to build a classification model using 13 physicochemical properties and 3 embryonic zebrafish assays that achieved a balanced accuracy of 91.7%. This work illustrates the power of a multi-dimensional in vivo platform to expand our ability to predict the hazard potential of new compounds based on structural relatedness, ultimately leading to reliable toxicity predictions based on chemical structure.

Maternal exposure to organophosphate flame retardants alters locomotor and anxiety-like behavior in male and female adult offspring

Endocrine disrupting chemicals (EDCs) are chemicals found in our environment that interrupt typical endocrine function. Some flame retardants (FRs) are EDCs as shown in their interaction with steroid and nuclear receptors. Humans are consistently exposed to flame retardants as they are used in everyday items such as plastics, clothing, toys, and electronics. Polybrominated diphenyl ethers were used as the major FR until 2004, when they were replaced by organophosphate flame retardants (OPFRs). Previous research in rodent models utilizing a commercial flame retardant mixture containing OPFRs reported alterations in anxiety-like behavior in the elevated plus maze (EPM) for rodents perinatally exposed to OPFRs. In the present study we utilize wild-type mice maternally exposed (gestational day 7 to postnatal day 14) to either an OPFR mixture of tris(1,3-dichloro-2-propyl), triphenyl phosphate, and tricresyl phosphate or a sesame seed oil vehicle. These mice were evaluated for anxiety-like behavior in adulthood on the open field test (OFT) and the light/dark box (LDB) as well as the EPM. Outcomes from the OFT and LDB indicate that males and females maternally exposed to OPFRs exhibit altered locomotor activity. Results of the EPM were sex-specific as we did not observe an effect in females; however, effects in males differed depending on exposure condition. Males maternally exposed to OPFRs exhibited an anxiolytic-like phenotype in contrast to their vehicle counterparts. This effect in perinatally OPFR-exposed males was not due to alterations in locomotor activity. Our research illustrates that there are sex- and exposure-dependent effects of perinatal OPFR exposure on adult locomotor and anxiety-like behaviors in a mouse model.

Organophosphate Esters: Are These Flame Retardants and Plasticizers Affecting Children's Health?

PURPOSE OF REVIEW

Organophosphate esters (OPEs) are applied to a variety of consumer products, primarily as flame retardants and plasticizers. OPEs can leach out of products over time and are consequently prevalent in the environment and frequently detected in human biomonitoring studies. Exposure during pregnancy is of particular concern as OPEs have recently been detected in placental tissues, suggesting they may be transferred to the developing infant. Also, studies have now shown that children typically experience higher exposure to several OPEs compared with adults, indicating they may be disproportionately impacted by these compounds. This review summarizes the current literature on reproductive and child health outcomes of OPE exposures and highlights areas for future research.

RECENT FINDINGS

Experimental animal studies demonstrate potential for OPEs to adversely impact health, and a limited number of epidemiologic studies conducted in adult cohorts suggest that OPEs may interfere with the endocrine system. Neurodevelopment is perhaps the most well studied of children's health endpoints, and several studies indicate that prenatal and early life OPE exposures impact both cognitive and behavioral development. Associations have also been reported with reproductive outcomes (e.g., fertilization and pregnancy loss) and with the timing of parturition and preterm birth. Cross-sectional studies also demonstrate associations between OPEs and respiratory health outcomes, allergic disease, and measures of adiposity. An expanding body of research demonstrates that OPEs are associated with adverse reproductive health and birth outcomes, asthma and allergic disease, early growth and adiposity, and neurodevelopment. Still, additional research is urgently needed to elucidate the full impact of OPEs on children's health.

Monitoring the levels of brominated and organophosphate flame retardants in passenger cars: Utilisation of car air filters as active samplers

Filters in residential and office air conditioning (A/C) systems have been used as sampling devices for monitoring different pollutants. However, cabin air filters (CAFs) in the A/C system of passenger cars have not been utilised for this purpose. In this study, we collected 22 used CAFs from passenger cars in Hanoi, Vietnam to analyse for 8 polybrominated diphenyl ethers (PBDEs) and 10 organophosphate esters (OPEs). All the analytes were detected in more than 50% of samples with the exception of BDE153 and BDE154. The average concentrations of ∑₁₀OPEs and ∑₈BDEs in the captured dust were 2600 and 40 ng/g, respectively with Tris (1-chloro-2-propyl) phosphate (TCIPP) and BDE209 as the dominant congener in OPE and BDE groups, respectively. CAFs are a potential tool to qualitatively assess the levels of semi-volatile chemicals in suspended dust in cars as a screening step for exposure assessment of those chemicals.

Comparing the Use of Silicone Wristbands, Hand Wipes, And Dust to Evaluate Children's Exposure to Flame Retardants and Plasticizers

Organophosphate esters (OPEs) are applied as additive flame retardants, and along with phthalates, are also used as plasticizers in consumer products. As such, human exposure is common and chronic. Deployed as personal passive samplers, silicone wristbands have been shown to detect over a thousand industrial and consumer product chemicals; however, few studies have evaluated chemical concentrations with their corresponding biomarkers of exposure, especially in children. Further, little is known about how well the wristbands predict individual exposure compared to existing validated external exposure tools such as indoor air, dust, and hand wipes. Here, we analyzed wristbands worn by children (ages 3-6) for 18 OPEs and 10 phthalates and compared them to corresponding urinary biomarkers. In wristbands, 13 of 18 OPEs and all phthalates were detected in >80% of wristbands, and 6 OPEs and 4 phthalates were significantly associated with corresponding urinary metabolites (r_s = 0.2-0.6, p < 0.05). When compared to paired hand wipes and house dust, wristbands were found to have similar or greater correlation coefficients with respective urinary biomarkers. These results suggest that wristbands can serve as effective and quantitative assessment tools for evaluating personal exposure to some OPEs and phthalates, and for certain chemicals, may provide a better exposure estimate than indoor dust.

In Vitro Metabolism of Isopropylated and tert-Butylated Triarylphosphate Esters Using Human Liver Subcellular Fractions

Isopropylated and tert-butylated triarylphosphate esters (ITPs and TBPPs, respectively) are plasticizers and flame retardants that are ubiquitous in indoor environments; however, no studies to date have characterized their metabolism. Using human liver subcellular S9 fractions, phase I and II in vitro metabolism of triphenyl phosphate (TPHP), 4-tert-butylphenyl diphenyl phosphate (4tBPDPP), 2-isopropylphenyl diphenyl phosphate (2IPPDPP), and 4-isopropylphenyl diphenyl phosphate (4IPPDPP) was investigated at 1 and 10 μM doses. Parent depletion and the formation of known or suspected metabolites (e.g., likely hydrolysis or hydroxylated products), including diphenyl phosphate (DPHP), hydroxyl-triphenyl phosphate (OH-TPHP), isopropylphenyl phenyl phosphate (ip-PPP), and tert-butylphenyl phenyl phosphate (tb-PPP), were monitored and quantified via GC/MS or LC-MS/MS. tb-PPP and its conjugates were identified as the major in vitro metabolites of 4tBPDPP and accounted for 71% and 49%, respectively, of the parent molecule that was metabolized during the incubation. While the mass balance between parents and metabolites was conserved for TPHP and 4tBPDPP, approximately 20% of the initial parent mass was unaccounted for after quantifying suspected metabolites of 2IPPDPP and 4IPPDPP that had authentic standards available. Two novel ITP metabolites, mono-isopropenylphenyl diphenyl phosphate and hydroxy-isopropylphenyl diphenyl phosphate, were tentatively identified by high-resolution mass spectrometry and screened for in recently collected human urine where mono-isopropenylphenyl diphenyl phosphate was detected in one of nine samples analyzed. This study provides insight into the biological fate of ITP and TBPP isomers in human tissues and is useful in identifying appropriate biomarkers of exposure to monitor, particularly in support of epidemiological studies.

Promotion effect of liver tumor progression in male kras transgenic zebrafish induced by tris (1, 3-dichloro-2-propyl) phosphate

A previous study reported that exposure to tris(1,3-dichloro-2-propyl) phosphate (TDCIPP) could promote the progression of hepatocellular carcinoma (HCC) in female HCC model zebrafish. Due to the existence of gender disparity in the development of HCC between females and males, whether the promotion effect of TDCIPP still exists in male HCC model zebrafish remains unclear. In this study, Tg(fabp10:rtTA2s-M2; TRE2:EGFP-kras^G12V), referred as kras transgenic zebrafish which was shown to be an inducible liver tumor model, was applied as experimental model to assess the promotion potential of TDCIPP for HCC in males. In brief, kras males were exposed to 20 mg/L doxycycline (DOX), 0.3 mg/L TDCIPP and a binary mixture of 20 mg/L DOX with 0.3 mg/L TDCIPP, and after exposure liver size, histopathology and transcriptional profiles of liver from these treatments were examined. With the involvement of TDCIPP, the liver size was significantly increased and the lesion of hepatocyte became more aggressive. Furthermore, expressions of genes involved in DNA replication and inflammatory response were simultaneously up-regulated in the treatment of TDCIPP compared with the solvent control and in the treatment of the binary mixture of the two chemicals compared to the single DOX treatment. Overall, our results suggested that TDCIPP had promotion effect on the progression of liver tumor in kras males.

Longer commutes are associated with increased human exposure to tris(1,3-dichloro-2-propyl) phosphate

Organophosphate esters (OPEs) are a class of semi-volatile organic compounds (SVOCs) used as flame retardants, plasticizers, and anti-foaming agents. Due to stringent flammability standards in vehicles and the ability of OPEs to migrate out of end-use products, elevated concentrations of OPEs have been found in car dust samples around the world. As many residents of Southern California spend a significant amount of time in their vehicles, there is potential for increased exposure to OPEs associated with longer commute times. As approximately 70% of the University of California, Riverside's undergraduate population commutes, the objective of this study was to use silicone wristbands to monitor personal exposure to OPEs and determine if exposure was associated with commute time in a subset of these students. Participants were asked to wear wristbands for five continuous days and complete daily surveys about the amount of time spent commuting. Data were then used to calculate a participant-specific total commute score. Components of Firemaster 550 (triphenyl phosphate, or TPHP, and isopropylated triaryl phosphate isomers) and Firemaster 600 (TPHP and tert-butylated triaryl phosphate isomers) - both widely used commercial flame retardant formulations - were strongly correlated with other OPEs detected within participant wristbands. Moreover, the concentration of tris(1,3-dichloro-2-propyl) phosphate (TDCIPP) was significantly correlated with the concentration of several Firemaster 500 components and tris(2-chloroisopropyl) phosphate (TCIPP). Finally, out of all OPEs measured, TDCIPP was significantly and positively correlated with total commute score, indicating that longer commutes are associated with increased human exposure to TDCIPP. Overall, our findings raise concerns about the potential for chronic TDCIPP exposure within vehicles and other forms of transportation, particularly within densely populated and traffic-congested areas such as Southern California.

Pruning chemicals from the green building landscape

Green building design has substantially minimized environmental impacts by reducing energy consumption compared with traditional buildings. Yet, it is not uncommon for a green building to meet the highest criteria for energy efficiency and be built with materials that contain chemicals hazardous to occupant health. Because of this discrepancy in achieving holistic sustainability, the architecture/engineering/construction (AEC) industry has never been more interested in occupant health and well-being than it is today. At the same time, numerous scientific studies have documented exposures to and associated health effects of chemicals used in building materials. Opportunities to translate environmental health research so that it is useful to the AEC community exist across the landscape of healthier buildings. For example, research can be conducted to prioritize building material and chemical combinations to demonstrate how green building certification systems, government building codes, and the building products marketplace can increase energy performance while also addressing the greatest chemical exposures and health impacts. In order for scientific research to be used to create and support healthier environments, researchers should design and translate their research with this landscape in mind and should consider experts in the AEC industry as ambassadors for change. We provide key examples of how scientists have promoted healthy building practices and highlight additional research opportunities.

The Influence of Environmentally Friendly Flame Retardants on the Thermal Stability of Phase Change Polyurethane Foams

To improve thermal insulation, microencapsulated phase change materials (micro-PCMs), expandable graphite (EG), and ammonium polyphosphate (APP) were introduced into polyurethane foam (PUF) to enhance the thermal stability and improve the thermal insulation behavior. The morphology of the PUF and micro-PCM was studied using a scanning electronic microscope (SEM), while the thermophysical properties of the PUF were investigated using a hot disk thermal constants analyzer and differential scanning calorimetry (DSC). The thermal stability of the PUF was investigated by thermogravimetric analysis (TGA), and the gas products volatilized from the PUF were analyzed by thermogravimetric analysis coupled with Fourier transform infrared spectrometry (TGA-FTIR). The results revealed that the thermal conductivities of the PUF were reduced because micro-PCM is effective in absorbing energy, showing that the PUF functions not only as a thermal insulation material but also as a heat sink for energy absorption. Moreover, the EG and APP were found to be effective in improving the thermal stabilities of the PUF, and the optimized formulation among EG, APP, and micro-PCMs in the PUF showed a significant synergistic effect.