Legacy and alternative flame retardants in Norwegian and UK indoor environment: Implications of human exposure via dust ingestion

Exposure to organophosphate esters among Inuit adults of Nunavik, Canada

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

Seasonal variations of organophosphate esters (OPEs) in atmospheric deposition, and their contribution to soil loading

Organophosphate esters (OPEs) are ubiquitous in surface soil, and atmospheric deposition is considered to be the major pollution source. However, the research on the environmental transport behaviors of OPEs between atmospheric deposition and soil is very limited. In this study, we investigated the contamination levels and seasonal variations of OPEs in atmospheric deposition samples (n = 33) collected from an area of South China every month between February 2021 and January 2022, and evaluated the contribution of OPEs in atmospheric deposition to soil. The concentrations of ∑21target-OPEs ranged from 3670 to 18,600 ng/g dry weight (dw), with a mean of 8200 ng/g dw (median: 7600 ng/g dw). ∑21target-OPEs concentrations in all atmospheric deposition samples exhibited significant seasonal differences (p < 0.05) with higher concentrations observed in winter and lower concentrations in summer. Tris(2,4-di-tert-butylphenyl) phosphate (TDTBPP) was the most dominant target OPE in atmospheric deposition (4870 ng/g dw), and its seasonal variation trend was consistent with ∑21OPEs (p < 0.05). Simultaneously, in order to further explore the effect of atmospheric deposition on the levels of OPEs in soil of the study region, input fluxes and accumulation increments were estimated. Ten OPEs (including seven target OPEs and three suspect OPEs) exhibited high input flux means and accumulation increments, indicating that these compounds are prone to accumulate in soil via atmospheric deposition. It is noteworthy that the non-target phosphonate analyte bis(2,4-di-tert-butylphenyl) dibutyl ethane-1,2-diylbis(phosphonate) (BDTBPDEDBP) was detected at highest median concentration (8960 ng/g dw) in atmospheric deposition. Correspondingly, the average input flux and accumulation increment of BDTBPDEDBP were higher than those of all target and suspect OPEs. Collectively, this study quantifies the environmental transport behavior of OPEs between atmospheric deposition and soil, and provides new evidences for the fact that atmospheric deposition is the important pollution source of OPEs in soil.

Polybrominated diphenyl ethers in indoor dust from Brazil: assessing demographic differences and human health exposure

Indoor house dust is considered an important human exposure route to polybrominated diphenyl ethers (PBDEs), which has raised concern about their environmental persistence and toxicity properties. In this study, eight PBDEs (BDE-28, -47, -99, -100, -153, -154, -183, and -209) were determined in house dust from two cities with different socio-demographic characteristics from Brazil, examining possible relationships with factors that potentially influence contamination (population density, economic activities, presence of electronic equipment, and so on) and also estimating the risk of human exposure through oral ingestion and dermal contact. The Σ8PBDE concentration in Sorocaba city ranged between 380 and 4269 ng/g dw, while in Itapetininga city ranged from 106 to 1000 ng/g dw. In both regions, BDE-209 was the most abundantly found congener, followed by BDE-99. House dust from Sorocaba presented significantly greater concentrations of BDE-183 and BDE-209 than Itapetininga. Regarding risk exposure assessment, the estimated daily intake (EDI) of PBDEs was much lower than their respective reference doses (RfDs) in all pathways estimated (non-dietary ingestion and dermal contact). This study provided valuable data to improve the knowledge about the presence and exposure to PBDEs in Brazilian house dust in comparison to other developing countries and the need to control environmental pollution and protect human health.

Determination of potential dermal exposure rates of phosphorus flame retardants via the direct contact with a car seat using artificial skin

Dermal exposure to phosphorus flame retardants (PFRs) has received much attention as a major alternative exposure route in recent years. However, the information regarding dermal exposure via direct contact with a product is limited. In addition, in the commonly used dermal permeability test, the target substance is dissolved in a solvent, which is unrealistic. In this study, a dermal permeability test of PFRs in three car seats was performed using artificial skin. The PFR concentrations in the car seats are 0.12 wt% tris(2-chloroethyl) phosphate (TCEP), 0.030-0.25 wt% tris(2-chloroisopropyl) phosphate (TCPP), 0.15 wt% triphenyl phosphate (TPhP), 0.89 wt% cresyl diphenyl phosphate (CsDPhP), 0.074 wt% tricresyl phosphate (TCsP), and 0.46-4.7 wt% diethylene glycol bis [di (2-chloroisopropyl) phosphate (DEG-BDCIPP). The mean skin permeation rates for a contact time of 24 h are 14 (TCEP), 5.4-160 (TCPP), 0.67 (CsDPhP), 0.38 (TPhP), and 3.3-58 ng cm-2 h-1 (DEG-BDCIPP). The concentrations of TCsP in receptor liquid were lower than the limit of quantification at the contact time of 24 h. The skin permeation rates were significantly affected by the type of car seat (e.g., fabric or non-fabric). The potential dermal TCPP exposure rate for an adult via direct contact with the car seat during the average daily contact time (1.3 h), which was the highest value assessed in this study, was estimated to be 16,000 ng kg-1 day-1, which is higher than that related to inhalation and dust ingestion reported as significant exposure route of PFRs in previous studies. These facts reveal that dermal exposure associated with direct contact with the product might be an important exposure pathway for PFRs.

Insights into the occurrence, spatial distribution, and ecological implications of organophosphate triesters in surface sediments from polluted urban rivers across China

Organophosphate triesters (tri-OPEs) are a kind of widespread contaminants in the world, particularly in China, which is a major producer and user of tri-OPEs. However, tri-OPE pollution in urban river sediments in China remains unclear. In current work, we carried out the first nationwide investigation to comprehensively monitor 10 conventional and five emerging tri-OPEs in sediments of 173 black-odorous urban rivers throughout China. Concentrations of 10 conventional and five emerging tri-OPEs were 3.8-1240 ng/g dw (mean: 253 ng/g dw) and 0.21-1107 ng/g dw (68 ng/g dw), respectively, and significantly differed among the cities sampled but generally decreased from Northeast and East China to Central and West China. These spatial patterns suggest that tri-OPE pollution was mainly from local sources and was controlled by the industrial and economic development levels in these four areas, as indicated by the significant correlations between tri-OPE concentrations and gross domestic production, gross industrial output, and daily wastewater treatment capacity. Although the tri-OPE composition varied spatially at different sites, which indicated different tri-OPE input patterns, it was commonly dominated by tris(2-chloroethyl) phosphate, tris(2-ethylhexyl) phosphate, and tris(1-chloro-2-propyl) phosphate (conventional tri-OPEs) and bisphenol A-bis(diphenyl phosphate) and isodecyl diphenyl phosphate (emerging tri-OPEs). A risk assessment indicated that tri-OPEs in most sampling sediments had a low to moderate risk to aquatic organisms.

Global patterns of human exposure to flame retardants indoors

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

Organophosphate Esters in Building Materials from China: Levels, Sources, Emissions, and Preliminary Assessment of Human Exposure

Source characteristics and health risks of indoor organophosphate esters (OPEs) are limited by the lack of knowledge on emission processes. This study attempted to integrate the contents and emissions of OPEs from indoor building materials to assess human health effects. Thirteen OPEs were investigated in 80 pieces of six categories of building materials. OPEs are ubiquitous in the building materials and ∑13OPE contents varied significantly (p < 0.05) from 72.8 ng/g (seam agent) to 109,900 ng/g (wallpaper). Emission characteristics of OPEs from the building materials were examined based on a microchamber method. Depending on the sample category, the observed initial area-specific emission rates of ∑13OPEs varied from 154 ng/m2/h (carpet) to 2760 ng/m2/h (wooden floorboard). Moreover, the emission rate model was developed to predict the release levels of individual OPEs, quantify source contributions, and assess associated exposure risks. Source apportionments of indoor OPEs exhibited heterogeneities in multiple environmental media. The joint OPE contribution of wallpaper and wooden floorboard to indoor dust was up to 94.8%, while latex paint and wooden floorboard were the main OPE contributors to indoor air (54.2%) and surface (76.1%), respectively. Risk assessment showed that the carcinogenic risks of tris(2-chloroethyl) phosphate (3.35 × 10-7) were close to the acceptable level (1 × 10-6) and deserved special attention.

Update of the risk assessment of polybrominated diphenyl ethers (PBDEs) in food

The European Commission asked EFSA to update its 2011 risk assessment on polybrominated diphenyl ethers (PBDEs) in food, focusing on 10 congeners: BDE-28, -47, -49, -99, -100, -138, -153, -154, -183 and ‑209. The CONTAM Panel concluded that the neurodevelopmental effects on behaviour and reproductive/developmental effects are the critical effects in rodent studies. For four congeners (BDE-47, -99, -153, -209) the Panel derived Reference Points, i.e. benchmark doses and corresponding lower 95% confidence limits (BMDLs), for endpoint-specific benchmark responses. Since repeated exposure to PBDEs results in accumulation of these chemicals in the body, the Panel estimated the body burden at the BMDL in rodents, and the chronic intake that would lead to the same body burden in humans. For the remaining six congeners no studies were available to identify Reference Points. The Panel concluded that there is scientific basis for inclusion of all 10 congeners in a common assessment group and performed a combined risk assessment. The Panel concluded that the combined margin of exposure (MOET) approach was the most appropriate risk metric and applied a tiered approach to the risk characterisation. Over 84,000 analytical results for the 10 congeners in food were used to estimate the exposure across dietary surveys and age groups of the European population. The most important contributors to the chronic dietary Lower Bound exposure to PBDEs were meat and meat products and fish and seafood. Taking into account the uncertainties affecting the assessment, the Panel concluded that it is likely that current dietary exposure to PBDEs in the European population raises a health concern.

Organophosphorus flame retardants and their metabolites in paired human blood and urine

Organophosphorus flame retardants (OPFRs) have been shown to be carcinogenic, neurotoxic, and endocrine disruptive, so it is important to understand the levels of OPFRs in human body as well as the modes of external exposure. In this study, we investigated the levels of 13 OPFRs and 7 phosphodiester metabolites in paired human blood and urine, as well as the influencing factors (region, age and gender), and studied the relationship between OPFRs and oxidative stress by urinary metabolites. We found that the concentrations of triphenyl phosphate (TPhP) and tris-(2-ethylhexyl) phosphate (TEHP) in the blood of urban populations were higher than those of rural populations, and that younger populations suffered higher TPhP and 2-ethylhexyl diphenyl phosphate (EHDPP) exposures than older populations. In addition, we found that tris-(2-chloroethyl) phosphate (TCEP), tributyl phosphate (TnBP), TPhP and EHDPP exposure induced oxidative stress. The results of the internal load principal component analysis indicated that dust ingestion, skin exposure, respiration and dietary intake may be the most important sources of TCEP, tris(2-butoxyethyl) phosphate (TBOEP), tri(2-chloroisopropyl) phosphate (TCIPP) and TEHP, respectively, and dust ingestion and skin exposure may be the main sources of TPhP for humans.

Emerging and traditional organophosphate esters in office air from Hangzhou, East China: Seasonal variations, influencing factors and human exposure assessment

Eight emerging and six traditional organophosphate esters (OPEs) were investigated in office air from Hangzhou China with all the traditional OPEs and 5 out of 8 emerging OPEs detected. The median concentrations of ∑traditional OPEs and ∑emerging OPEs were 61,200 and 5.81 pg/m3, respectively. Butylphenyl diphenyl phosphate (BPDPP) and trisisopropyltrisphenyl phosphate (TIPPP) were observed for the first time in indoor air and Chinese office, respectively. The levels of ∑traditional OPEs decreased in the following order: summer > autumn > spring > winter. Conversely, no obvious trends were observed for emerging OPEs. ∑traditional OPEs (p < 0.001) and tri(chloroisopropyl) phosphate (TCIPP) (p < 0.01) concentrations were positively correlated with temperature. Interestingly, ∑emerging OPEs and the individual emerging OPEs analytes had no significant correlations with temperature (p > 0.05). ∑traditional OPEs, tris(2-chloroethyl) phosphate (TCEP) and TCIPP levels were significantly positively correlated with relative humidity (p < 0.05), while ∑emerging OPEs levels were negatively correlated with relative humidity (p < 0.05). Median intakes of traditional OPEs were estimated to be several orders of magnitude lower than the corresponding Reference Dose (RfD) values. The distinct environmental behaviors of emerging OPEs compared to traditional OPEs, coupled with the lack of established RfD values for them, underscore the need for their risk evaluations in future.

Reconciling chemical flame retardant exposure and fire risk in domestic furniture

INTRODUCTION

Evidence suggests that standards for resistance of furniture to ignition may lead to an increase in use of chemical flame retardants (CFRs). This is motivating the development of new approaches that maintain high levels of fire safety while facilitating a reduction in use of CFRs. However, reconciling potential fire risk with use of CFRs in relation to specific policy objectives is challenging.

OBJECTIVES

To inform the development of a new policy in the UK for the fire safety of furniture, we developed for domestic furniture quantitative models of fire risk and potential for CFR exposure. We then combined the models to determine if any lower fire risk, higher CFR exposure categories of furniture were identifiable.

METHODS

We applied a novel mixed-methods approach to modelling furniture fire risk and CFR exposure in a data-poor environment, using literature-based concept mapping, qualitative research, and data visualisation methods to generate fire risk and CFR exposure models and derive furniture product rankings.

RESULTS

Our analysis suggests there exists a cluster of furniture types including baby and infant products and pillows that have comparable overall properties in terms of lower fire risk and higher potential for CFR exposure.

DISCUSSION

There are multiple obstacles to reconciling fire risk and CFR use in furniture. In particular, these include a lack of empirical data that would allow absolute fire risk and exposure levels to be quantified. Nonetheless, it seems that our modelling method can potentially yield meaningful product clusters, providing a basis for further research.

Prenatal exposure to emerging and traditional organophosphate flame retardants: Regional comparison, transplacental transfer, and birth outcomes

During gestation, organophosphate flame retardants (OPFRs) have the potential to pose health risks to fetuses due to their ability to cross the placental barrier. However, data are scarce regarding the transplacental transfer of these compounds, particularly concerning emerging OPFRs and regional variations. In this study, we analyzed 14 traditional OPFRs and 5 emerging OPFRs in maternal and cord serum samples from Mianyang and Hangzhou, two cities in eastern and western China, respectively. The results revealed marked disparities in the overall levels of OPFRs between the two cities (p < 0.05), with the average concentration in maternal serum being higher in Hangzhou (14.55 ng/mL) than in Mianyang (8.28 ng/mL). The most abundant compounds found in both cities were tris (2-chloroethyl) phosphate (TCEP), Triphenyl phosphate (TPHP), and Tri-n-butyl phosphate (TnBP). Additionally, this study marked the first detection of novel OPFRs, including resorcinol bis (diphenyl phosphate) (RDP), isodecyl diphenyl phosphate (IDDPP), cresyl diphenyl phosphate (CDP), and bisphenol A bis (diphenyl phosphate) (BPA-BDPP) in maternal and cord serum simultaneously with the detection frequencies higher than 45%. This study also found that transplacental transfer efficiencies for OPFRs varied by ester group, with Aryl-OPFRs exhibiting the highest transfer rates (0.90-1.11) and Alkyl-OPFRs exhibiting the lowest (0.66-0.83). Transfer efficiencies exhibited a positive correlation with log Kow values (p < 0.05), suggesting that hydrophobic OPFRs with higher log Kow values are more likely to permeate the placental barrier. Moreover, the exposure levels of Tris (1,3-dichloro-2-propyl) phosphate (TDCIPP), Tri (Chloropropyl) Phosphate (TCIPP), TPHP, and CDP in cord serum were negatively associated (p < 0.05) with birthweight of newborns. This research adds to our understanding of the transplacental transfer of OPFRs and the possible health risks associated with prenatal exposure.

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

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

Parental Exposure to Environmentally Relevant Concentrations of Bisphenol-A Bis(diphenyl phosphate) Impairs Vascular Development in Offspring through DNA/RNA Methylation-Dependent Transmission

Bisphenol-A bis(diphenyl phosphate) (BDP) has been increasingly detected in indoor environmental and human samples. Little is known about its developmental toxicity, particularly the intergenerational effects of parental exposure. In this study, adult zebrafish were exposed to BDP at 30-30,000 ng/L for 28 days, with results showing that exposure did not cause a transfer of BDP or its metabolites to offspring. Vascular morphometric profiling revealed that parental exposure to BDP at 30 and 300 ng/L exerted significant effects on the vascular development of offspring, encompassing diverse alterations in multiple types of blood vessels. N6-Methyladenosine (m6A) methylated RNA immunoprecipitation sequencing of larvae in the 300 ng/L group revealed 378 hypomethylated and 350 hypermethylated m6A peaks that were identified in mRNA transcripts of genes crucial for vascular development, including the Notch/Vegf signaling pathway. Concomitant changes in 5 methylcytosine (m5C) DNA methylation and gene expression of m6A modulators (alkbh5, kiaa1429, and ythdf1) were observed in both parental gonads and offspring exposed to BDP. These results reveal that parental exposure to low concentrations of BDP caused offspring vascular disorders by interfering with DNA and RNA methylation, uncovering a unique DNA-RNA modification pattern in the intergenerational transmission of BDP's developmental toxicity.

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

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

Occurrence and risk of human exposure to organophosphate flame retardants in indoor air and dust in Hanoi, Vietnam

The presence and distribution of thirteen organophosphate flame retardants (OPFRs) were investigated in indoor air and dust samples collected in Hanoi, Vietnam. The total OPFRs (ƩOPFRs) concentrations in indoor air and dust samples were 42.3-358 ng m^-3 (median 101 ng m^-3) and 1290-17,500 ng g^-1 (median 7580 ng g^-1), respectively. The profile of OPFRs in both indoor air and dust indicated that tris(1-chloro-2-propyl) phosphate (TCIPP) was the most dominant compound with a median concentration of 75.3 ng m^-3 and 3620 ng g^-1, contributing 75.2% and 46.1% to ƩOPFRs concentrations in indoor air and dust, respectively, followed by tris(2-butoxyethyl) phosphate (TBOEP), with a median concentration of 16.3 ng m^-3 and 2500 ng g^-1, contributing 14.1% and 33.6% to ƩOPFRs concentrations in indoor air and dust, respectively. The levels of OPFRs in the indoor air samples and corresponding indoor dust samples showed a strong positive correlation. The total estimated daily intakes (EDI_total) of ƩOPFRs (via air inhalation, dust ingestion, and dermal absorption) for adults and toddlers under the median and high exposure scenarios were 36.7 and 160 ng kg^-1 d^-1, and 266 and 1270 ng kg^-1 d^-1, respectively. Among the investigated exposure pathways, dermal absorption was a primary exposure pathway to OPFRs for both toddlers and adults. The hazard quotients (HQ) ranged from 5.31 × 10^-8 to 6.47 × 10^-2 (<1), and the lifetime cancer risks (LCR) were from 2.05 × 10^-11 to 7.37 × 10^-8 (<10^-6), indicating that human health risks from exposure to OPFRs in indoor environments are not significant.

Adipogenic and endocrine disrupting mixture effects of organic and inorganic pollutant mixtures

Chronic health conditions are rapidly increasing in prevalence and cost to society worldwide: in the US, >42 % of adults aged 20 and older are currently classified as obese. Exposure to endocrine disrupting chemicals (EDCs) has been implicated as a causal factor; some EDCs, termed "obesogens", can increase weight and lipid accumulation and/or perturb metabolic homeostasis. This project aimed to assess the potential combination effects of diverse inorganic and organic contaminant mixtures, which more closely reflect environmentally realistic exposures, on nuclear receptor activation/inhibition and adipocyte differentiation. Herein, we focused on two polychlorinated biphenyls (PCB-77 and 153), two perfluoroalkyl substances (PFOA and PFOS), two brominated flame retardants (PBB-153 and BDE-47), and three inorganic contaminants (lead, arsenic, and cadmium). We examined adipogenesis using human mesenchymal stem cells and receptor bioactivities using luciferase reporter gene assays in human cell lines. We observed significantly greater effects for several receptor bioactivities by various contaminant mixtures relative to individual components. All nine contaminants promoted triglyceride accumulation and/or pre-adipocyte proliferation in human mesenchymal stem cells. Comparing simple component mixtures to individual components at 10 % and 50 % effect levels revealed putative synergistic effects for each of the mixtures for at least one of the concentrations relative to the individual component chemicals, some of which also exhibited significantly greater effects than the component contaminants. Our results support further testing of more realistic and complex contaminant mixtures that better reflect environmental exposures, in order to more conclusively define mixture responses both in vitro and in vivo.

Levels, distribution, childhood exposure assessment, and influencing factors of polybrominated diphenyl ethers (PBDEs) in household dust from nine cities in China

Household dust is an important source of premature exposure to polybrominated diphenyl ethers (PBDEs), especially for children. In this onsite study, 246 dust samples were collected from 224 households in nine Chinese cities during 2018-2019. Questionnaires were administered to explore the association between household-related information and PBDEs in household dust. The median concentration of Σ₁₂PBDEs in household dust from 9 cities was 138 ng/g (94-227 ng/g), with the arithmetic mean of 240 ± 401 ng/g. Among the nine cities, the highest median concentration of Σ₁₂PBDEs in household dust was found in Mianyang (295.57 ng/g), while the lowest was found in Wuxi (23.15 ng/g). BDE-71 was the most dominant congener, ranging from 42.08 % to 98.15 % of the 12 PBDE congeners among 9 cities. Three potential sources for the indoor environment were Penta-BDE, Octa-BDE commercial products, and photolytic bromine from Deca-BDEs based on the largest contribution (81.24 %). Under the moderate exposure scenario, the exposure levels through ingestion and dermal absorption for children were 7.30 × 10^-1 ng/kg BW/day and 3.26 × 10^-2 ng/kg BW/day, respectively. Temperature, CO₂, years of residence, income, family size, household size, use of computers, heating, use of insecticide, and use of humidifiers were influential factors for PBDE concentrations in household dust. Based on the evidence of the correlation between PBDEs and these household parameters, it can be applied to reduce PBDE concentrations in household dust, which is a basis for controlling PBDEs pollution in Chinese households and protecting population health.

A new consensus on reconciling fire safety with environmental & health impacts of chemical flame retardants

Flame retardants are chemical substances that are intended to mitigate fire safety risks posed by a range of goods including furniture, electronics, and building insulation. There are growing concerns about their effectiveness in ensuring fire safety and the potential harms they pose to human health and the environment. In response to these concerns, on 13 June 2022, a roundtable of experts was convened by the UKRI Six Clean Air Strategic Priorities Fund programme 7. The meeting produced a Consensus Statement that summarises the issues around the use of flame retardants, laying out a series of policy recommendations that should lead to more effective fire safety measures and reduce the human and environmental health risks posed by these potentially toxic chemicals.

A review on organophosphate esters: Physiochemical properties, applications, and toxicities as well as occurrence and human exposure in dust environment

Organophosphate esters (OPEs) are widely used as flame retardants and plasticizers in the world. The use of OPEs has increased rapidly due to the prohibition of polybrominated diphenyl ethers. However, OPEs are mainly added to various materials by physical mixing, they are therefore easy to be released into the environment through volatilization, leaching, and abrasion during their production, use, transportation, and after disposal. Dust, as an important medium for human exposure to OPEs, has attracted extensive attention. Here, this article reviewed the current knowledge on the physiochemical properties, consumptions and applications, and ecotoxicities of OPEs, also synthesized the available data on the occurrence of 13 OPEs in outdoor and indoor dust environments around the world over the past decade. The results showed that the sum of OPEs (ΣOPEs) was the highest in outdoor dust from an e-waste disposal area in Tianjin of China (range: 1390-42700 ng/g dw; mean: 11500 ng/g dw). The highest ΣOPEs was found in Japan for home dust (range: 9300-11000000 ng/g dw; mean: 266543 ng/g dw), Sweden for office dust (range: 14000-1600000 ng/g dw; mean: 360100 ng/g dw) and daycare center dust (range: 40000-4600000 ng/g dw; mean: 1990800 ng/g dw), and Brazil for car dust (range: 108000-2050000 ng/g dw; mean: 541000 ng/g dw). The use pattern of OPEs differed in different regions and countries. The exposure and risk assessment based on the data of OPEs in home dust indicated that the average daily intakes of OPEs via dust ingestion for children and adults were lower than the corresponding reference doses; and that the current human exposure to OPEs through indoor dust ingestion were not likely to pose risks to human health. Finally, the review pointed out the gaps of current research and provided the directions for further study on OPEs in dust environment.

Exposure to Novel Brominated Flame Retardants and Organophosphate Esters and Associations with Thyroid Cancer Risk: A Case-Control Study in Eastern China

Novel brominated flame retardant (NBFR) and organophosphate ester (OPE) exposure may engender adverse effects on human health. However, present epidemiological information regarding the effects of such exposure is limited and controversial. In this case-control study, 481 serum samples were collected from patients with thyroid cancer (n = 242) and healthy controls (n = 239) in Shandong Province, eastern China. The levels of NBFRs and OPEs, thyroid hormones, and serum lipid parameters were measured in all the participants. Pentabromotoluene, 2,3-dibromopropyl 2,4,6 tribromophenyl ether, decabromodiphenylethane (DBDPE), tris (2-chloroethyl) phosphate (TCEP), and triphenyl phosphate (TPP) were widely detected (detection frequency > 60%) in all the participants. A significantly high risk association was found between exposure of NBFRs and OPEs (namely 1,2,3,4,5-pentabromobenzene, DBDPE, tri-n-propyl phosphate, tri[(2R)-1-chloro-2-propyl] phosphate, tris (1,3-dichloro-2-propyl) phosphate, and tris (2-butoxyethyl) phosphate) and thyroid cancer in both males and females. In the females of the control group, TCEP levels exhibited a significantly positive association with thyroid-stimulating hormone and a negative association with triiodothyronine (T3), free triiodothyronine (FT3), and free thyroxine (FT4) levels. Weighted quantile sum regression evaluated the mixed effects of the compounds on thyroid hormones levels and thyroid cancer. As a result, TPP accounted for the majority of the T3, thyroxine, and FT3 amounts. Our results suggest that NBFR and OPE exposure contributes to alterations in thyroid function, thereby increasing thyroid cancer risk.

Distribution and health risks of organic micropollutants from home dusts in Malaysia

Indoor dust is an important medium to evaluate human exposure to emerging organic contaminants. The principal aim of this study was to determine overall status of organic micropollutants (OMPs) of indoor dust in Kuala Lumpur, Malaysia and assess their corresponding health risks. One hundred thirty-three OMPs, ascribed to 13 chemical groups, were screened by Automated Identification and Quantification System with a GC-MS database. The concentrations of OMPs ranged between 460 and 4000 μg/g, with the median concentration of 719 μg/g. The dominant chemical groups were ascribed to n-alkanes (median: 274 μg/g), plasticizers (151 μg/g), sterols (120 μg/g), and pesticides (42.6 μg/g). Cholestrol was the most abundant compound (median: 115 μg/g). Different sources and usage patterns of OMPs in various houses were expected. Toxicity values of OMPs were obtained from existing databases or predicted by quantitative structure-activity relationship models. Cumulative hazard quotients for OMPs through ingestion route were lower than one for all the dust samples, demonstrating that there was no remarkable non-cancer risk. The cancer risks of these OMPs were greater than 10^-4, with cholestrol dominating 99.1% of the carcinogenic risks, which suggested that there was a significant cancer risk. This study might offer a benchmark to ensure the safety of chemical usages in future in Malaysia.

Organophosphate esters in UK diet; exposure and risk assessment

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

Distribution and source of and health risks associated with polybrominated diphenyl ethers in dust generated by public transportation

Carcinogenic and neurotoxic polybrominated diphenyl ethers (PBDEs) are environmentally ubiquitous and have been widely investigated. However, little is understood regarding their pollution status, sources, and potential risk to persons in public transportation microenvironments (PTMs). We collected 60 dust samples from PTMs and then selected four materials typical of bus interiors to determine the sources of PBDEs in dust using principal component analysis coupled with Mantel tests. We then evaluated the risk of PBDEs to public health using Monte Carlo simulations. We found that PBDE concentrations in dust were 2-fold higher in buses than at bus stops and that brominated diphenyl ether (BDE)-209 was the main pollutant. The number of buses that passed through a bust stop contributed to the extent of PBDE pollution, and the primary potential sources of PBDEs in dust were plastic handles and curtains inside buses; BDE-209 and BDE-154 were the main contributors of pollution. We found that health risk was 8-fold higher in toddlers than in adults and that the reference doses of PBDEs in dust were far below the United States Environmental Protection Agency limits. Our findings provide a scientific basis that may aid in preventing PBDE pollution and guiding related pollution management strategies in PTMs.

Occurrence of newly identified plasticizers in handwipes; development and validation of a novel analytical method and assessment of human exposure via dermal absorption

A novel analytical method for the monitoring of four newly identified plasticizers, namely di-propylene glycol dibenzoate (DiPGDB), tri-n-butyl trimellitate (TBTM), isooctyl 2-phenoxyethyl terephthalate (IOPhET) and bis 3,5,5-trimethylhexyl phosphate (TMHPh), in handwipes based on pulverization was developed and in-house validated. In total, 164 handwipe samples (paired with house dust and human urine) were collected during winter (n = 82) and summer (n = 82) 2019 from adults and toddlers living in Flanders, Belgium. Method LOQs ranged from 1 to 200 ng/g. The ranges of Σ_plasticizers were 70-5400 ng/g for winter and 70-3720 ng/g for summer. The detection frequencies were 39% for DiPGDB, 27% for TBTM and <5% for IOPhET and TMHPh in winter samples and 33% for DiPGDB, 21% for TBTM and <10% for IOPhET and TMHPh in summer ones. The dominant compound in handwipes was DiPGDB, with mean contributions of 74% and 83% for winter and summer, followed by TBTM (24% and 9.2%), TMHPh (1.8% and 8.1%) and IOPhET (<1% and <1%). Σ_plasticizers concentrations were positively correlated in summer with the use of sanitizer (r = 0.375, p < 0.05) and negatively correlated in winter with the use of personal care products (r = -0.349, p < 0.05). DiPGDB was found positively correlated with the age of the participants (r = 0.363, p < 0.05) and the time spent indoors (r = 0.359, p < 0.05), indicating indoor environment as a potential source. Levels of TBTM in handwipes were positively correlated with dust samples collected from the same households (r = 0.597, p < 0.05), and those detected in toddler handwipes were significantly higher compared to adults (p < 0.05). Human daily exposure via dermal absorption was evaluated using the dermal derived no effects level values (DNEL), available in the database of the European Chemicals Agency (ECHA) and estimated using the theoretical bio-accessible fractions per compound. Toddler exposure to TBTM was significantly higher compared to adults (T-test, p < 0.05). No risk for adverse human health effects was derived from the comparison with DNELs for all compounds.

Characterization of organophosphate esters (OPEs) and polyfluoralkyl substances (PFASs) in settled dust in specific workplaces

An analytical method for detecting flame retardants was slightly modified and optimized for the simultaneous determination of 11 organophosphate esters (OPEs) and 26 polyfluoralkyl substances (PFASs) contained in dust. All the analytes were determined in HPLC/MS-MS, and OPEs were also analyzed in GC/MS, and the results were compared. The study was conducted through the investigation of the Standard Reference Material SRM 2585 of the National Institute of Standard and Technology (NIST). The results were compared with the available reference mass fraction reported in the NIST certificate. The mass fraction obtained for the other OPEs and PFASs was compared to available data in the literature. After verifying the reliability of the results, the method was applied to environmental samples of settled dust, collected in four workplaces, where OPE and PFAS content is expected to be higher than in house dust: a mechanical workshop, an electronic repair center, a disassembly site, and a shredding site of two electronic waste recycling plants. By analyzing both PFASs and OPEs in the same samples, the present work demonstrated that the selected working places were more polluted in OPEs than houses; on the contrary, PFAS content in house dust proved to be more than ten times higher than that in workplaces. Additional research is necessary to confirm these data. Nevertheless, because this preliminary study showed not negligible concentrations of OPEs in some workplaces and of PFASs in houses, their monitoring should be extended to other domestic and selected working sites.

Changes in levels of legacy and emerging organophosphorus flame retardants and plasticizers in indoor dust from a former e-waste recycling area in South China: 2013-2017

To assess the impacts of e-waste regulations on environmental pollution, the levels, compositions, and human exposure assessment of organophosphorus flame retardants (PFRs), emerging PFRs (ePFRs), phthalate esters (PAEs), and alternative plasticizers (APs) were investigated in indoor dust samples collected from homes in a former e-waste dismantling area in 2013 and in 2017, 4 years after the implementation of legislation and regulations governing e-waste dismantling activities in this area. The median concentrations of ΣPFRs, ΣePFRs, ΣPAEs, and ΣAPs in dust decreased from 5680, 1650, 167,200, and 140,600 ng/g in 2013 to 1210, 476, 95,000, and 45,300 ng/g in 2017, respectively, suggesting that the national and local regulations prohibiting primitive e-waste dismantling activities is effective in mitigating the pollution status for these chemicals. In the analyzed dust samples, tris(1-chloro-2-propyl) phosphate (TCIPP), triphenyl phosphate (TPHP), resorcinol bis(diphenylphosphate) (RDP), and bisphenol A-bis(diphenyl phosphate) (BDP) were the major PFRs/ePFRs, contributing to 77% and 76% of the total PFRs/ePFRs in 2013 and 2017, respectively. Di(2-ethylhexyl) phthalate (DEHP), di-iso-nonyl phthalate (DINP), di-iso-decyl phthalate (DIDP), and di-n-butyl phthalate (DNBP) were the major PAEs/APs, with contributions of 89% and 95% for the total PAEs/APs in 2013 and 2017, respectively. The results of the human exposure assessment demonstrated that exposure to these levels of the target chemicals via dust ingestion and dermal contact was unlikely to cause health concerns for local residents.

Bioaccessibility-based monitoring and risk assessment of indoor dust-bound PAHs collected from housing and public buildings: Effect of influencing factors

Polycyclic aromatic hydrocarbons (PAHs) bounded in indoor dust have significant effects in residents' health. Although various researches has evaluated exposure to PAHs in some indoor areas around the world, no work has been conducted on bioaccessibility of indoor PAHs in the buildings of Bushehr city. Therefore, dust samples were collected from various indoor microenvironments including residential buildings (RB), office buildings (OB), commercial buildings (CB), industrial buildings (IB), school classroom (SC), laboratory (LR), drugstores (DS), beauty salons (BS), smoking cafés (SC) and restaurants (Res) - 10 from each microenvironment. In order to determine the levels of polycyclic aromatic hydrocarbons (PAHs), bioaccessible PAHs, and sink sorption PAHS were analyzed in them. The results showed that the highest level of these contaminants was detected in SC and the lowest in Lab. The median concentration of dust-bound ΣPAHs, bioaccessible ΣPAHs, and sink sorption ΣPAHs in the SC samples were 10,890.00, 1157.92, and 297.28 ng/g, and they were 1160.00, 19.69, and 0.75 ng/g in Lab samples. The results also indicated that the ΣPAHs concentration had a negative and significant association with the ventilation rate (pvalue <0.05 in most cases), as well as a positive and significant relationship with smoking inside buildings (pvalue <0.05). The estimated daily intake (EDI) values calculated for residential buildings (RB) were higher compared to most of the other studied microenvironments. These observations can be due to the fact that people spend much more time in residential buildings (50% of the entire day) compared to occupational settings (22%). Thus, they intake more dust within a longer time, and are hence exposed to larger amounts of pollutants bound with these particles.

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

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

Emerging and legacy flame retardants in indoor air and dust samples of Tarragona Province (Catalonia, Spain)

Flame retardants (FRs) are widely used in consumer products including furniture foam and electronic equipment such as computers, monitors and TVs. Over time, FRs can easily migrate into the surrounding environments. Since brominated FRs (BFRs) has been determined of high concern due to their environmental persistence, bioaccumulation and potential toxicity, novel FRs have emerged. The present study was aimed at identifying and quantifying the indoor levels of 41 legacy and novel FRs, which include 20 OPFRs and 21 HFRs (8 PBDEs, 3 HBCDDs, 5 NBFRs and 5 DECs) in Tarragona Province (Catalonia, Spain). The results have confirmed the presence of both legacy and novel FRs in air and dust of homes, schools and offices. To the best of our knowledge, this is the first European study measuring OPFRs at office environments and also confirming the presence of the following OPFRs: TEP, TCIPP, T2IPPP, TPPO, DCP, TMCP and B4IPPPP in indoor air, even some of them at high levels. OPFRs in general and TCIPP in particular showed high concentrations in air (94,599 pg/m³ and 72,281 pg/m³, respectively) and dust (32,084 ng/g and 13,496 ng/g, respectively) samples collected in indoor environments. HBCDDs were found at high levels in dust (32,185 ng/g), whereas the presence of PBDEs and DECs were low in both matrices (<160 pg/m³ in air and <832 ng/g in dust). NBFRs showed higher levels than the two legacy FRs groups, which is supported by the current restrictions of these FRs (640 pg/m³ in air and 1291 ng/g in dust). Samples of schools had significantly lower levels of NBFRs, but significantly higher concentrations of HFRs in air than in home samples, while dust levels of HFRs were significantly lower than those in samples of offices. Regarding human health risks, the current assessment suggests that those derived from exposure to FRs were lower -although close- to assumable risks, evidencing the potential of FRs for non-carcinogenic and carcinogenic risks, mainly due to the exposure to TCIPP, which was the main contributor together with ΣHBCDDs and also EHDPP.

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

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

Gridded emission inventory of organophosphorus flame retardants in China and inventory validation

The bioaccumulation and adverse effects of organophosphorus flame retardants (OPFRs) on human health have become a global concern. China produces the largest amount of OPFRs globally and has the highest global market share. However, little is known about its emission level and environmental cycling, thereby causing uncertainties in the assessment of the environmental and health impacts of OPFRs. We developed a gridded annual OPFRs emission inventory at 1/4° longitude by 1/4° latitude resolution over China from 2014 to 2018. The results show that the annual OPFRs emissions increased from approximately 670 tons/yr in 2014 to 1000 tons/yr in 2018 in China. Higher OPFR emissions were identified in Jiangxi, Shandong, Beijing-Tianjin-Hebei (BTH), Yangtze River Delta (YRD), and Pearl River Delta (PRD). In total, 2400 tons of OPFRs were released into the atmosphere during the multi-year period, in which production accounting for 56.6% of total OPFR emissions in China. An atmospheric transport model, the Canadian Model for Environmental Transport of Organochlorine Pesticides (CanMETOP), was employed to verify the gridded emission inventory and elucidate the atmospheric environmental fate of OPFRs. Modeled OPFRs in the air and soil agreed reasonably well with observed data, suggesting that the developed inventory was, to a large extent, reliable. The modeled atmospheric and surface soil concentrations of OPFRs across China ranged from 0 to 119 ng/m³ and 0 to 428 ng/g, respectively. East China is subjected to more intense OPFR contamination than the rest of the country. The results provide a valuable dataset and assessment of OPFRs, which may aid policy-makers and the scientific community in developing emission control strategies and evaluating the health and environmental consequences of OPFRs in China.

Toxic organic pollutants in Greek house dust: Implications for human exposure and health risk

Organic contaminants often documented in house dust include mainly chemicals released from construction materials and consumer products and compounds emitted from indoor combustion activities. The occurrence of major chemical classes of toxic organic pollutants, included polybrominated diphenyl ethers (PBDEs), polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs) and nitrated polycyclic aromatic hydrocarbons (NPAHs), was for the first time investigated in house dust in Greece. The mean concentrations of ∑₁₆PAHs, ∑₂₀PBDEs, ∑₇NPAHs and∑₁₅PCBs in house dust were 4650 ng g^-1, 564 ng g^-1, 7.52 ng g^-1, and 6.29 ng g^-1, respectively. Exposure to dust organic contaminants via ingestion, inhalation and dermal absorption was estimated for two age classes (adults and children) and carcinogenic and non-carcinogenic risks were assessed. The hazard index (HI) for adults and children for PBDEs, PCBs, PAHs and NPAHs in all samples was less than 1 suggesting a very low level of concern for all human age group due to exposure to those chemicals. Total carcinogenic risk via the three exposure pathways (ingestion, inhalation and dermal contact) was within the safe range of 10^-6 to 10^-4.

Human health risks from brominated flame retardants and polycyclic aromatic hydrocarbons in indoor dust

Exposure to dust particles containing toxic compounds is linked to serious health outcomes, including cancer. The purpose of this study was to determine if indoor dust from houses and cars contained harmful levels of brominated flame retardants (polybrominated diphenyl ethers, PBDEs) and polycyclic aromatic hydrocarbons (PAHs), and to assess their potential toxicity to adults and children. In Kuwait, the median concentration of total PBDEs (Ʃ14- PBDEs) was 408.55 μg PBDEs/kg dust in houses and twice as high in cars (838.52 μg PBDEs/kg dust), while total PAHs (Ʃ16-PAHs) were similar in houses (992.81 μg PAHs/kg) and cars (900.42 μg PAHs/kg). The PBDEs and PAHs concentrations in indoor dust were related to house age and square footage, car model year, and natural ventilation. Furthermore, a higher PBDEs concentration was associated with electronic devices that operate continuously, furniture containing foam treated with PBDEs, and cars that are parked outdoors, since PBDEs tend to be volatilized under these conditions. The PAHs concentration in indoor dust increased with smoking and proximity to major roads and industrial facilities, which are major PAHs sources. The hazard quotient and total cancer risk for PBDEs in indoor dust were within safe limits, but indoor dust with higher PAHs concentrations had hazard quotients from 5.51 to 11.23 and total cancer risk of 10^-3 for adults and children. We conclude that exposure to PAHs-contaminated indoor dust from houses and cars where smoking occurs can increase the cancer risk of adults and children.

Impact of dietary exposure to low-dose tris(1,3-dichloro-2-propyl)phosphate in allergic asthmatic mice

OBJECTIVE

Tris(1,3-dichloro-2-propyl)phosphate (TDCIPP) is an organophosphorus flame retardant that is an alternative to brominated flame retardants. Although TDCIPP can adversely affect human health, information about its effects on immune and allergic responses is scarce. We aimed to investigate the effects of dietary exposure to TDCIPP using less than the human tolerable daily intake (TDI) in allergic asthmatic mice.

METHODS

Male C3H/HeJSlc mice were fed a chow diet containing TDCIPP equivalent to 0.02 μg/kg/day (low; L), 0.2 μg/kg/day (medium; M), or 2 μg/kg/day (high; H) and were intratracheally administered ovalbumin (OVA, 1 μg/animal) every 2 weeks from 5 to 11 weeks of age.

RESULTS

In OVA-treated mice, TDCIPP-H exposure tended to enhance pulmonary inflammation compared with vehicle exposure. TDCIPP dose-dependently decreased mRNA level of G protein-coupled estrogen receptor (GPER) in the lungs with or without OVA. OVA + TDCIPP-H treatment tended to increase the total cell number and promoted CD4⁺ cell activation compared with OVA alone treatment in mediastinal lymph nodes. In splenocytes, an increase in the fraction of Breg cells, but not of total B and T cells, and an increase in IL-5 in cell culture supernatants following OVA re-stimulation in OVA + TDCIPP-H-treated mice was observed compared with OVA-alone-treated mice. Moreover, OVA + TDCIPP-H exposure decreased Gr-1 expression in bone marrow (BM) cells.

DISCUSSION

These results suggested that dietary exposure to TDCIPP at TDI level slightly enhances allergic diseases, such as allergic asthma, via GPER regulation at inflamed sites and secondary lymphoid tissue and BM cell alternations.

Optimization and validation of a two-step method for the determination of polybrominated diphenyl ethers in Croatian house dust samples

Microwave-assisted extraction was applied as a method for extraction of seven polybrominated diphenyl ether (PBDE) congeners (28, 47, 99, 100, 153, 154, and 183) from house dust samples. Optimization of MAE experimental conditions was achieved using a multivariate design approach, and the results indicated that only the choice of extraction solvent had a statistically significant influence on extraction efficiency. The extract purification step was also investigated in detail with a goal to achieve effective cleaning, with minor solvent consumption. As the final operating conditions, 20 min MAE extraction from 1 g of dust with 20 mL of n-hexane : acetone (1 : 1, v/v) at 80 °C and extract purification on an in-lab prepared column containing 2 g of neutral silica and 4 g of acidified silica, whereby the PBDEs were eluted from the column with 15 mL of n-hexane : dichloromethane (4 : 1, v/v), were selected. The extracts were analyzed on a dual GC-μECD system, and GC-MS/MS was used as a confirmatory method. The performance of the optimized method was validated by analyzing spiked dust samples and a standard reference material (NIST 2585 "Organic Contaminants in House Dust"). Congener specific PBDE recovery ranged from 76% to 90% for the spiked samples (with very good repeatability; RSD < 7%) and the measured mass concentrations of selected PBDEs were in excellent agreement with certified values for a standard reference material. The proposed method was successfully applied to the analysis of targeted PBDEs in house dust samples.

Organophosphate esters in airborne particles from subway stations

For the first time, the concentrations of 19 organophosphate esters (OPEs) were measured in airborne fine particulate matter (PM2.5) from subway stations in Barcelona (Spain) to investigate their occurrence, contamination profiles and associated health risks. OPEs were detected in all PM2.5 samples with levels ranging between 1.59 and 202 ng/m³ (mean value of 39.9 ng/m³). Seventeen out of 19 tested analytes were detected, with TDClPP, TClPP and TCEP being those presenting the highest concentrations. OPE concentrations are not driven by the same factors that determine the ambient PM2.5 concentrations of other constituents in the subway. Newer stations presented higher OPE levels, probably due to the materials used in the design of the platforms, with greater use of modern plastic materials versus older stations with tiles and stones. Estimated daily intakes via airborne particles inhalation during the time expended in subway stations were calculated, as well as the carcinogenic and non-carcinogenic health risks (CR and non-CR), all being much lower than the threshold risk values. Thus, subway inhalation exposure when standing on the platform to OPE's per se is not considered to be dangerous for commuters.

Legacy and alternative brominated, chlorinated, and organophosphorus flame retardants in indoor dust-levels, composition profiles, and human exposure in Latvia

Flame retardants (FRs) are additives used in consumer products to reduce flammability, even though they can easily contaminate the indoor environment. Since it is common for people in modern cities to spend up to 85% of time indoors, the quality of the indoor environment is critical for human health. In this study, polybrominated diphenyl ethers (PBDEs), organophosphorus flame retardants (OPFRs), emerging brominated flame retardants (EBFRs), and dechlorane-related compounds (DRCs) were measured in household dust samples (n = 34) from Latvia, followed by human exposure assessment. Among all studied compounds, OPFRs showed the highest concentrations (1380-133,000 ng g^-1). Despite the phase-out of PBDEs, they were the second most significant flame retardants in the studied dust samples (468-25,500 ng g^-1) and the predominant compound was BDE-209. The concentrations of EBFRs were in the range of 120-7295 ng g^-1, with the most abundant contaminant being DBDPE, which is widely used as a substitute for the deca-BDE formulation. DRCs were the least common flame retardants in the Latvian indoor environments, with concentrations ranging 22.4-192 ng g^-1. Although the concentrations of specific FRs are known to vary between different countries, the levels and patterns observed in dust samples from Latvia were similar to those reported from Central Europe. Human exposure was evaluated as the estimated daily intake (EDI). The calculated exposure to most of the FRs was several orders of magnitude lower than the available reference dose (RfD) values.

Organophosphate flame retardants and diesters in the urine of e-waste dismantling workers: associations with indoor dust and implications for urinary biomonitoring

Indoor dust ingestion is one of the main pathways for human exposure to organophosphate flame retardants (PFRs). The urinary concentrations of diesters (DAPs) are usually used as biomarkers to assess human exposure to PFRs. In this study, the PFR and DAP levels were measured in morning and evening urine samples of 30 workers from an e-waste dismantling site in southern China. The indoor dust samples were also collected from workshops and houses for analyzing associations between PFR and DAP levels in urine and dust. Tris(1-chloro-2-propyl) phosphate (TCIPP) and triphenyl phosphate (TPHP) were the dominant PFRs in dust, while bis(2-chloroethyl) phosphate (BCEP) and diphenyl phosphate (DPHP) were the major DAPs in dust. A significant positive correlation was observed between TPHP and DPHP concentrations in dust (p < 0.001), suggesting their potentially same source and the degradation of TPHP to form DPHP. TCIPP and tris(1,3-dichloro-2-propyl) phosphate (TDCIPP) were the predominant PFRs, and BCEP, bis(1,3-dichloro-2-propyl) phosphate (BDCIPP), and DPHP were the main DAPs in both the morning and evening urine samples. The DPHP levels in evening urine samples were significantly correlated with TPHP and DPHP levels (p < 0.01) in dust. A similar correlation was found for the BCEP levels in the evening urine samples and the TCEP and BCEP levels (p < 0.01) in dust. These results indicated that in addition to being biotransformed from their respective parent PFRs, direct ingestion from indoor dust could also be the potential source for urinary DPHP and BCEP. Since relatively low detection frequencies were observed for bis(1-chloro-2-propyl) phosphate (BCIPP) and bis(butoxyethyl) phosphate (BBOEP) in urine, they may not be the major metabolites of TCIPP and tris(2-butoxyethyl) phosphate (TBOEP), respectively, in the human body. However, BDCIPP can be considered a useful biomarker because it is a unique metabolite of TDCIPP and has high detection frequencies in urine samples. The results of this study indicated the limitations of solely using urinary DAPs as biomarkers for the evaluation of human exposure to PFRs, and certain PFRs as well as hydroxylated PFRs (OH-PFRs) should also be considered for urinary biomonitoring in future studies.

Characterization of adipogenic, PPARγ, and TRβ activities in house dust extracts and their associations with organic contaminants

In this study, we sought to expand our previous research on associations between bioactivities in dust and associated organic contaminants. Dust samples were collected from central NC homes (n = 188), solvent extracted, and split into two fractions, one for analysis using three different bioassays (nuclear receptor activation/inhibition and adipocyte development) and one for mass spectrometry (targeted measurement of 124 organic contaminants, including flame retardants, polychlorinated biphenyls, perfluoroalkyl substances, pesticides, phthalates, and polycyclic aromatic hydrocarbons). Approximately 80% of dust extracts exhibited significant adipogenic activity at concentrations that are comparable to estimated exposure for children and adults (e.g. ~20 μg/well dust) via either triglyceride accumulation (65%) and/or pre-adipocyte proliferation (50%). Approximately 76% of samples antagonized thyroid receptor beta (TRβ), and 21% activated peroxisome proliferator activated receptor gamma (PPARγ). Triglyceride accumulation was significantly correlated with TRβ antagonism. Sixty-five contaminants were detected in at least 75% of samples; of these, 26 were correlated with adipogenic activity and ten with TRβ antagonism. Regression models were used to evaluate associations of individual contaminants with adipogenic and TRβ bioactivities, and many individual contaminants were significantly associated. An exploratory g-computation model was used to evaluate the effect of mixtures. Contaminant mixtures were positively associated with triglyceride accumulation, and the magnitude of effect was larger than for any individually measured chemical. For each quartile increase in mixture exposure, triglyceride accumulation increased by 212% (RR = 3.12 and 95% confidence interval: 1.58, 6.17). These results suggest that complex mixtures of chemicals present in house dust may induce adipogenic activity in vitro at environmental concentrations and warrants further research.

Discovery of New Protein Targets of BPA Analogs and Derivatives Associated with Noncommunicable Diseases: A Virtual High-Throughput Screening

BACKGROUND

Bisphenol A analogs and derivatives (BPs) have emerged as new contaminants with little or no information about their toxicity. These have been found in numerous everyday products, from thermal paper receipts to plastic containers, and measured in human samples.

OBJECTIVES

The objectives of this research were to identify in silico new protein targets of BPs associated with seven noncommunicable diseases (NCDs), and to study their protein-ligand interactions using computer-aided tools.

METHODS

Fifty BPs were identified by a literature search and submitted to a virtual high-throughput screening (vHTS) with 328 proteins associated with NCDs. Protein-protein interactions between predicted targets were examined using STRING, and the protocol was validated in terms of binding site recognition and correlation between in silico affinities and in vitro data.

RESULTS

According to the vHTS, several BPs may target proteins associated with NCDs, some of them with stronger affinities than bisphenol A (BPA). The best affinity score (the highest in silico affinity absolute value) was obtained after docking 4,4'-bis(N-carbamoyl-4-methylbenzensulfonamide)diphenylmethane (BTUM) on estradiol 17-beta-dehydrogenase 1 (-13.7 kcal/mol). However, other molecules, such as bisphenol A bis(diphenyl phosphate) (BDP), bisphenol PH (BPPH), and Pergafast 201 also exhibited great affinities (top 10 affinity scores for each disease) with proteins related to NCDs.

DISCUSSION

Molecules such as BTUM, BDP, BPPH, and Pergafast 201 could be targeting key signaling pathways related to NCDs. These BPs should be prioritized for in vitro and in vivo toxicity testing and to further assess their possible role in the development of these diseases. https://doi.org/10.1289/EHP7466.

Organophosphate ester flame retardants have antiandrogenic potential and affect other endocrine related endpoints in vitro and in silico

Organophosphate ester flame retardants (OPFRs) are used to prevent ignition and spreading of fire. They are present in various human matrices suggesting adult, fetal, and neonate exposure. Endocrine related effects have been observed in vivo, but information at the molecular level is lacking for some OPFRs. Also, a better understanding of potential contribution from chemical substructures is needed. The aim of this study was to screen OPFRs for endocrine disruptive potential in vitro and in silico. We selected eleven substances to represent some OPFRs with 1) little information on endocrine activity and others to represent 2) varied chemical substructures. We used in vitro assays for androgen receptor (AR), aryl hydrocarbon receptor (AhR), and Nrf2 activity, effects on steroidogenesis, and transthyretin (TTR) binding, as well as in silico models covering estrogen, thyroid, and CYP3A4 induction related endpoints. Ten OPFRs affected AR and AhR activity, seven affected TTR binding, and five affected 17β-estradiol levels. Several substances had IC₅₀-values below 10 μM and exhibited efficacious effects. These included TPHP, CDP, TMPP, TIPPP, and EHDPP for AR antagonism, suggesting that the degree of arylation and the size of the substance can play a role for the activity. Chlorinated OPFRs had low/no effect on TTR binding. No clear trend was observed for AhR and steroidogenesis, but all arylated OPFRs were predicted to have alert for estrogen receptor binding in an in silico model with metabolism simulator included. Collectively, our data suggest that OPFRs have endocrine disruptive potential warranting further studies to enable human risk assessment.

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.

A review on organophosphate flame retardants in indoor dust from China: Implications for human exposure

To investigate the status of organophosphate flame retardants (OPFRs) in indoor dust in China, published scientific studies were systematically collected and analyzed. The analysis revealed large variations among microenvironments, including offices (median: 14.59 μg/g) and e-waste workshops (median: 13.36 μg/g), with high levels of OPFRs contamination. Chlorinated organophosphate ester flame retardants (Cl-OPFRs) were the dominant OPFRs (52-75%) in most indoor dust samples; however, in e-waste workshops, aryl- and alkyl-OPFRs were the most abundant. As an alternative flame retardant to polybrominated diphenyl ethers (PBDEs), OPFRs concentrations have increased in recent years in indoor environments in China. Urban sources are of greatest concern: Shanghai (mean: 13.54 μg/g), Guangzhou (mean: 10.76 μg/g), and Beijing (mean: 9.37 μg/g) have high ΣOPFRs contamination levels in indoor dust. Compared to other countries, the OPFRs concentrations in indoor dust in all studied microenvironments from China (median: 8.81 μg/g) were low. The estimated daily intakes of ΣOPFRs by dust ingestion for adults and children were 2.12 and 11.06 ng/kg/body weight/day (average), respectively. Human exposure to OPFRs through the accidental intake of indoor dust does not pose a direct health risk to the Chinese population. However, indoor dust ingestion is an important route for human exposure to OPFRs.

Pet hair as a potential sentinel of human exposure: Investigating partitioning and exposures from OPEs and PAHs in indoor dust, air, and pet hair from China

We investigated the levels, compositions, and partitioning behaviors of organophosphate esters (OPEs) and polycyclic aromatic hydrocarbons (PAHs) in indoor air, dust, and pet hair from North China, as well as their potential exposures for humans and pets. The mean OPE concentrations in the indoor air (n = 19), dust (n = 26), and pet hair (n = 29) samples were 52.1 ng/m³, 3510 ng/g, and 1440 ng/g; while the mean PAH concentrations were 369 ng/m³, 6000 ng/g, and 22.6 ng/g, respectively. The matrix-air partitioning of OPEs and PAHs may reach equilibrium for compounds with octanol-air partition coefficients (logK_oa) between 7 and 11 for dust and logK_oa < 12 for pet hair. Correlation analysis suggested that pet hair could be used as a sentinel for the exposure to certain PAHs, e.g., phenanthrene (PHE) or fluoranthene (FLA), via exposure to indoor air. This work suggests that pet hair may be a better sentinel than air and dust for human exposure to OPEs and PAHs across different indoor microenvironments. Estimated daily intakes (EDIs) to OPEs and PAHs via air inhalation, dust ingestion, and dermal absorption were calculated for children, adults, and pets. The median ΣEDIs for children, adults, and pets were 26.7, 5.40, and 55.0 ng/kg/day for ΣOPEs, and 68.8, 19.1, and 130 ng/kg/day for ΣPAHs, respectively. Air inhalation was the main exposure route to PAHs and OPEs with logK_oa < 10, whereas dust ingestion was the main exposure route to those with logK_oa > 10.

Beyond Traditional Organophosphate Triesters: Prevalence of Emerging Organophosphate Triesters and Organophosphate Diesters in Indoor Dust from a Mega E-waste Recycling Industrial Park in South China

Numerous studies have reported the environmental contamination with traditional organophosphate triesters (tri-OPEs), but there is very little information on emerging tri-OPEs and organophosphate diesters (di-OPEs), especially in e-waste recycling areas. In this study, we conducted a comprehensive survey to monitor a broad suite of 11 traditional tri-OPEs, 12 emerging OPEs, and 10 di-OPEs in indoor dust collected from the workshops of (n = 42) and residential homes adjacent to (n = 24) a mega e-waste recycling industrial park in South China. In addition to traditional tri-OPEs, all of the emerging OPEs and di-OPEs were frequently detected in the dust samples. Total concentrations of emerging tri-OPEs and di-OPEs were in the range of 1210-62 900 and 2010-55 600 ng/g in the workshop dust and 435-23 700 and 186-4350 ng/g in the local home dust, respectively, which were comparable to those of traditional tri-OPEs (1160-61 500 and 370-13 900 ng/g, respectively). Most OPEs exhibited significantly higher concentrations in workshop dust versus local home dust (p < 0.05), indicating that e-waste dismantling activities contributed to the high residues of OPEs in indoor dust. Correlation analysis revealed that tri-OPEs have some common emission sources, i.e., e-waste and household products, while di-OPEs could originate from different sources, e.g., tri-OPE degradation, direct commercial application, and impurities in tri-OPE formulas. For both occupational workers and local adults, the median estimated daily intake values of emerging tri-OPEs (7.5 and 1.7 ng/kg bw/day, respectively) and di-OPEs (3.9 and 0.2 ng/kg bw/day, respectively) were comparable to that of traditional tri-OPEs (4.3 and 1.0 ng/kg bw/day, respectively), which suggests the important contribution of the emerging tri-OPEs and di-OPEs to the overall risks of human external exposure to OPE chemicals.

Legacy and emerging organophosphorus flame retardants and plasticizers in indoor microenvironments from Guangzhou, South China

Indoor dust has been extensively used for assessment of indoor contamination, especially for semi-volatile organic compounds (SVOCs). In the present study, the occurrence of four groups of SVOCs, i.e. organophosphorus flame retardants (PFRs), emerging PFRs (ePFRs), legacy phthalates (LPs), and alternative plasticizers (APs), was investigated in the indoor dust and air collected from floors, table surfaces, windows, and air conditioner (A/C) filters in bedrooms and offices in Guangzhou, South China. In bedrooms, A/C filter dust showed the highest median concentrations of PFRs (4670 ng/g) and ePFRs (586 ng/g), whilst the highest median concentrations of LPs and APs were found in floor (240,880 ng/g) and window dust (157,160 ng/g), respectively. In offices, A/C filter dust showed the highest median concentrations for PFRs (6750 ng/g) and APs (504,520 ng/g), while the highest ePFR median level was found in PC table dust (5810 ng/g) and LPs in floor dust (296,270 ng/g). Median air concentrations of PFRs, ePFRs, LPs, and APs were measured at 4.6, 0.12, 399, and 25 ng/m³ in bedrooms, and at 8.0, 0.05, 332, and 43 ng/m³ in offices, respectively. Tris(1-chloro-iso-propyl) phosphate (TCIPP) was the predominant PFRs/ePFRs in both dust and air. Di(2-ethylhexyl) phthalate (DEHP), di-iso-decyl phthalate (DIDP) and di-iso-nonyl phthalate (DINP) were the main LP/AP compounds in dust, whilst di-iso-butyl phthalate (DIBP) and di-n-butyl phthalate (DNBP) were the most abundant LPs/APs in air. A significant correlation (p < 0.05) was found between dust and air levels for chemicals with log K_oa < 14, indicating that equilibrium was achieved for these chemicals but not for those with log K_oa > 14. Among the investigated human exposure pathways (i.e. dust ingestion, dermal absorption, and air inhalation), dust ingestion was the predominant one for all chemicals. Human exposures of this magnitude to these chemicals through the investigated pathways was unlikely to present a health risk in the present study.

Characterization and health risk assessment of organophosphate esters in indoor dust from urban and rural domestic house and college dormitory in Nanjing, China

Indoor dust is an important route of exposure for organophosphate esters (OPEs), which are associated with adverse health effects. In the present study, the pollution occurrence and potential health risks of 13 OPEs in indoor dust from urban homes, college dormitories, and rural homes in Nanjing were investigated. Most OPEs were detected in the tested samples. College dormitories dust samples showed significantly higher OPEs concentrations (132.31-1.61 × 10³ ng/g), followed by that in urban homes (31.42-49.84 ng/g) and rural homes (51.19-309.75 ng/g). The Mann-Whitney U test found no significant difference in the total concentrations of OPEs except for some individual OPEs between urban and rural homes. Tris (2-chloroisopropyl) phosphate (TCPP) was the most abundant compound in all tested areas. Spearman correlation coefficients and principal component analysis indicated that OPEs might originate from different sources in three microenvironments. Estimated exposures for adults and children in all indoor dust were below the relevant reference doses. Additionally, TCPP was the primary contributors to the non-carcinogenic risk, ranging from 1.07 × 10^-6 to 2.20 × 10^-5. Tris (2,3-dibromopropyl) phosphate was the dominant carcinogenic risk contributor in indoor dust, with a range of 1.33 × 10^-11 to 8.74 × 10^-10. These results suggested that the health risk of OPEs was within acceptable limits in the tested areas.

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.