Associations between allergic symptoms and phosphate flame retardants in dust and their urinary metabolites among school children

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.

Exposure to organophosphate esters and maternal-child health

Organophosphate esters (OPEs) are a class of chemicals now widely used as flame retardants and plasticizers after the phase-out of polybrominated diphenyl ethers (PBDEs). However, OPEs carry their own risk of developmental toxicity, which poses concern for recent birth cohorts as they have become ubiquitous in the environment. In this review, we summarize the literature evaluating the association between OPE exposure and maternal, perinatal, and child health outcomes. We included original articles investigating associations of OPE exposure with any health outcome on pregnant women, newborns, children, and adolescents. We found 48 articles on this topic. Of these, five addressed maternal health and pregnancy outcomes, 24 evaluated prenatal OPE exposure and child health, 18 evaluated childhood OPE exposure and child/adolescent health, and one article evaluated both prenatal and childhood OPE exposure. These studies suggest that OPE exposure is possibly associated with a wide range of adverse health outcomes, including pregnancy loss, altered gestational duration and smaller birthweight, maternal and neonatal thyroid dysfunction, child metabolic dysregulation and abnormal growth, impaired neurodevelopment, and changes in immune response. Many of the reported outcomes associated with OPE exposure varied by child sex. Findings also varied substantially by OPE metabolite and exposure time. The OPEs most frequently measured, detected, and found to be associated with health outcomes were triphenyl phosphate (TPHP, metabolized to DPHP) and tris(1,3-dichloro-2-propyl) phosphate (TDCIPP, metabolized to BDCIPP). The extensive range of health outcomes associated with OPEs raises concern about their growing use in consumer products; however, these findings should be interpreted considering the limitations of these epidemiological studies, such as possible exposure misclassification, lack of generalizability, insufficient adjustment for covariates, and failure to consider chemical exposures as a mixture.

Prenatal risk factors of indoor environment and incidence of childhood eczema in the Japan Environment and Children's Study

The quality of indoor environment is a risk factor for early childhood eczema and atopic dermatitis; however, its influence during pregnancy on childhood eczema in Japan has not been investigated. In this study, we aimed to determine the indoor environmental factors that are associated with eczema in children up to 3 years of age, using national birth cohort data from the Japan Environment and Children's Study (JECS). Information on indoor environments and eczema symptoms until 3 years of age was collected using self-administered questionnaires to the mothers. A total of 71,883 and 58,639 mother-child pairs at 1.5- and 3-years-old, respectively, were included in the former analyses. To account for prenatal indoor risk factors, 17,568 (1.5-years-old) and 7063 (3-years-old) children without indoor mold and/or ETS exposure were included in the final analysis. A higher mold index, gas heater use, parquet flooring use, and frequent insecticide use showed significantly increased risks for childhood eczema up to 3 years of age. These associations were consistent after stratification analysis among children whose parents did not have a history of allergies. The updated WHO guidelines on indoor air quality should be implemented based on recent findings regarding the effects of prenatal exposure to indoor dampness on health effects of children further in life, including asthma, respiratory effects, eczema, and other immunological effects.

Nephrotoxicity of organophosphate flame retardants in patients with chronic kidney disease: A 2-year longitudinal study

Humans are extensively exposed to organophosphate flame retardants (OPFRs), an emerging group of organic contaminants with potential nephrotoxicity. Nevertheless, the estimated daily intake (EDI) and prognostic impacts of OPFRs have not been assessed in individuals with chronic kidney disease (CKD). In this 2-year longitudinal study of 169 patients with CKD, we calculated the EDIs of five OPFR triesters from urinary biomonitoring data of their degradation products and analyzed the effects of OPFR exposure on adverse renal outcomes and renal function deterioration. Our analysis demonstrated universal OPFR exposure in the CKD population, with a median EDIΣOPFR of 360.45 ng/kg body weight/day (interquartile range, 198.35-775.94). Additionally, our study revealed that high tris(2-chloroethyl) phosphate (TCEP) exposure independently correlated with composite adverse events and composite renal events (hazard ratio [95 % confidence interval; CI]: 4.616 [1.060-20.096], p = 0.042; 3.053 [1.075-8.674], p = 0.036) and served as an independent predictor for renal function deterioration throughout the study period, with a decline in estimated glomerular filtration rate of 4.127 mL/min/1.73 m2 (95 % CI, -8.127--0.126; p = 0.043) per log ng/kg body weight/day of EDITCEP. Furthermore, the EDITCEP and EDIΣOPFR were positively associated with elevations in urinary 8-hydroxy-2'-deoxyguanosine and kidney injury molecule-1 during the study period, indicating the roles of oxidative damage and renal tubular injury in the nephrotoxicity of OPFR exposure. To conclude, our findings highlight the widespread OPFR exposure and its possible nephrotoxicity in the CKD population.

Personal environmental exposure to plasticizers and organophosphate flame retardants using silicone wristbands and urine: Patterns, comparisons, and correlations

Plasticizers (PLs) and organophosphate flame retardants (OPFRs) are ubiquitous in the environment due to their widespread use and potential for leaching from consumer products. Environmental exposure is a critical aspect of the human exposome, revealing complex interactions between environmental contaminants and potential health effects. Silicone wristbands (SWBs) have emerged as a novel and non-invasive sampling device for assessing personal external exposure. In this study, SWBs were used as a proxy to estimate personal dermal adsorption (EDdermal) to PLs and OPFRs in Belgian participants for one week; four morning urine samples were also collected and analyzed for estimated daily intake (EDI). The results of the SWBs samples showed that all the participants were exposed to these chemicals, and the exposure was found to be highest for the legacy and alternative plasticizers (LP and AP), followed by the legacy and emerging OPFRs (LOPFR and EOPFR). In urine samples, the highest levels were observed for metabolites of diethyl phthalate (DEP), di-isobutyl phthalate (DiBP) and di-n-butyl phthalate (DnBP) among LPs and di(2-ethylhexyl) terephthalate (DEHT) for APs. Outliers among the participants indicated that there were other sources of exposure that were not identified. Results showed a significant correlation between EDdermal and EDI for DiBP, tris (2-butoxyethyl) phosphate (TBOEP) and triphenyl phosphate (TPhP). These correlations indicated their suitability for predicting exposure via SWB monitoring for total chemical exposure. The results of this pilot study advance our understanding of SWB sampling and its relevance for predicting aggregate environmental chemical exposures, while highlighting the potential of SWBs as low-cost, non-invasive personal samplers for future research. This innovative approach has the potential to advance the assessment of environmental exposures and their impact on public health.

Relationship between flame retardants and respiratory health- A systematic review and meta-analysis of observational studies

Chronic respiratory diseases are a dealing cause of death and disability worldwide. Their prevalence is steadily increasing and the exposure to environmental contaminants, including Flame Retardants (FRs), is being considered as a possible risk factor. Despite the widespread and continuous exposure to FRs, the role of these contaminants in chronic respiratory diseases is yet not clear. This study aims to systematically review the association between the exposure to FRs and chronic respiratory diseases. Searches were performed using the Cochrane Library, MEDLINE, EMBASE, PUBMED, SCOPUS, ISI Web of Science (Science and Social Science Index), WHO Global Health Library and CINAHL EBSCO. Among the initial 353 articles found, only 9 fulfilled the inclusion criteria and were included. No statistically significant increase in the risk for chronic respiratory diseases with exposure to FRs was found and therefore there is not enough evidence to support that FRs pose a significantly higher risk for the development or worsening of respiratory diseases. However, a non-significant trend for potential hazard was found for asthma and rhinitis/rhinoconjunctivitis, particularly considering urinary organophosphate esters (OPEs) including TNBP, TPHP, TCEP and TCIPP congeners/compounds. Most studies showed a predominance of moderate risk of bias, therefore the global strength of the evidence is low. The limitations of the studies here reviewed, and the potential hazardous effects herein identified highlights the need for good quality large-scale cohort studies in which biomarkers of exposure should be quantified in biological samples.

Biotransformation of Organophosphate Diesters Characterized via In Vitro Metabolism and In Vivo Screening

Organophosphate diesters (di-OPEs), as additives in industrial applications and/or transformation products of emerging environmental pollutants, such as organophosphate triesters (tri-OPEs), have been found in the environment and biological matrices. The metabolic fate of di-OPEs in biological media is of great significance for tracing the inherent and precursor toxicity variations. This is the first study to investigate the metabolism of a suite of di-OPEs by liver microsomes and to identify any metabolite of metabolizable di-OPEs in in vitro and in vivo samples. Of the 14 di-OPEs, 5 are significantly metabolizable, and their abundant metabolites with hydroxyl, carboxyl, dealkylated, carbonyl, and/or epoxide groups are tentatively identified. More than half of the di-OPEs are detectable in human serum and/or wild fish tissues, and dibenzyl phosphate (DBzP), bis(2,3-dibromopropyl) phosphate (BDBPP), and isopropyl diphenyl phosphate (ip-DPHP) are first reported at a detectable level in humans and wildlife. Using an in vitro assay and a known biotransformation rule-based integrated screening strategy, 2 and 10 suspected metabolite peaks of DEHP are found in human serum and wild fish samples, respectively, and are then identified as phase I and phase II metabolites of DEHP. This study provides a novel insight into fate and persistence of di-OPE and confirms the presence of di-OPE metabolites in humans and wildlife.

Associations of urinary organophosphate esters metabolites with asthma and lung function in adolescents

BACKGROUND

Organophosphate esters (OPEs) are ubiquitously detected in environments and their exposure may affect respiratory health. However, epidemiological evidence, particularly among adolescents, is very limited.

OBJECTIVE

We aimed to investigate the associations of urinary OPEs metabolites with asthma and lung function among adolescents and to identify potential effect modifiers.

METHODS

Included were 715 adolescents aged 12-19 years old participating in the National Health and Nutrition Examination Survey (NHANES) 2011-2014. Multivariable binary logistic regression and linear regression were used to assess associations with asthma and lung function, respectively. Stratified analyses were conducted to assess the effect modifications of serum sex hormones, vitamin D levels, and body mass index (BMI).

RESULTS

After multivariable adjustment, we found that bis(2-chloroethyl) phosphate (BCEP) (3rd tertile [T3] vs 1st tertile [T1], OR = 1.87, 95% CI: 1.08, 3.25; P-trend=0.029) and diphenyl phosphate (DPHP) (T3 vs T1, OR = 2.52, 95%CI: 1.25, 5.04; P-trend=0.013) were associated with elevated odds of asthma in all adolescents. Sex-stratified analyses revealed that associations of these two OPEs metabolites tended to be stronger in males. Meanwhile, BCEP and the molecular sum of OPEs metabolites (∑OPEs) were significantly associated with declined lung function, either in all adolescents or by sex. Furthermore, stratified analyses revealed that positive associations of OPEs metabolites with asthma tended to be stronger among adolescents with insufficient levels of Vitamin D (VD < 50 nmol/L), relatively high levels of total testosterone (≥356 ng/dL and ≥22.5 ng/dL for males and females, respectively), or low levels of estradiol (<19.1 pg/mL and <47.3 pg/mL for males and females, respectively).

SIGNIFICANCE

Certain urinary OPEs metabolites, especially DPHP and BCEP, were associated with elevated odds of asthma and declined lung function in adolescents. Such associations might be partly modified by levels of VD and sex steroid hormones.

IMPACT STATEMENT

The observed associations of urinary OPEs metabolites with increased risk of asthma and declined lung function highlight the potential hazard of OPEs exposure to respiratory health among adolescents.

Role of inflammatory lipid and fatty acid metabolic abnormalities induced by plastic additives exposure in childhood asthma

Lipid metabolism play an essential role in occurrence and development of asthma, and it can be disturbed by phthalate esters (PAEs) and organophosphate flame retardants (OPFRs). As a chronic inflammatory respiratory disease, the occurrence risk of childhood asthma is increased by PAEs and OPFRs exposure, but it remains not entirely clear how PAEs and OPFRs contribute the onset and progress of the disease. We have profiled the serum levels of PAEs and OPFRs congeners by liquid chromatography coupled with mass spectrometry, and its relationships with the dysregulation of lipid metabolism in asthmatic, bronchitic (acute inflammation) and healthy (non-inflammation) children. Eight PAEs and nine OPFRs congeners were found in the serum of children (1 - 5 years old) from Shenzhen, and their total median levels were 615.16 ng/mL and 17.06 ng/mL, respectively. Moreover, the serum levels of mono-methyl phthalate (MMP), tri-propyl phosphate (TPP) and tri-n-butyl phosphate (TNBP) were significant higher in asthmatic children than in healthy and bronchitic children as control. Thirty-one characteristic lipids and fatty acids of asthma were screened by machine-learning random forest model based on serum lipidome data, and the alterations of inflammatory characteristic lipids and fatty acids including palmitic acids, 12,13-DiHODE, 14,21-DiHDHA, prostaglandin D2 and LysoPA(18:2) showed significant correlated with high serum levels of MMP, TPP and TNBP. These results imply PAEs and OPFRs promote the occurrence of childhood asthma via disrupting inflammatory lipid and fatty acid metabolism, and provide a novel sight for better understanding the effects of plastic additives on childhood asthma.

Individual and combined effects of phthalate metabolites on eczema in the United States population

Phthalates might trigger immune dysregulation. The relationship between a phthalate mixture exposure and eczema remains unclear. To address this research gap, four statistical models were used to investigate the individual, combined, and interaction relationships between monoesters of phthalates (MPAEs) and eczema, including the logistic regression, weighted quantile sum regression (WQS), quantile g computation (qg-computation), and bayesian kernel machine regression (BKMR). Moreover, subgroup analyses were performed by sex and age. After adjusting for all covariates, the logistic regression model suggested a positive correlation between mono-(3-carboxypropyl) phthalate (MCPP) and eczema. Subgroup analysis suggested that the effect of the MPAEs on eczema was predominantly present in men and children. In the WQS model, the joint effect of 11 MPAEs on eczema was marginally significant [odds ratio = 1.36, 95% confidence interval: 0.97-1.90]. Moreover, a positive association was observed between the combined exposure to 11 MPAEs and eczema in the BKMR model. MCPP and mono-(carboxynonyl) phthalate were the most substantial risk factors based on the results of WQS and qg-computation models. The exposure to a mixture of MPAEs may lead to an elevated prevalence of eczema in the United States population, with men and children being particularly vulnerable to their effects.

Organophosphate esters (OPEs) and novel brominated flame retardants (NBFRs) in indoor dust: A systematic review on concentration, spatial distribution, sources, and human exposure

In recent years, the indoor exposure of organophosphate esters (OPEs) and novel brominated flame retardants (NBFRs) has received widespread attention worldwide. Using published data on 6 OPEs in 23 countries (n = 1437) and 2 NBFRs in 18 countries (n = 826) in indoor dust, this study systematically reviewed the concentrations, spatial distribution, sources and exposure risk of 8 flame retardants (FRs) worldwide. Tris(chloroisopropyl)phosphate (TCIPP) is the predominant FR with a median concentration of 1050 ng g-1 ΣCl-OPEs are significantly higher than Σnon-Cl-OPEs (p < 0.05). ΣOPEs in indoor dust from industrially-developed countries are higher than those from the countries lacking industrial development. Household appliances, electronics and plastic products are the main sources of non-Cl-OPEs and NBFRs, while interior decorations and materials contribute abundant Cl-OPEs in indoor dust. The mean hazard index (HI) of TCIPP for children is greater than 1, possibly posing non-cancer risk for children in some countries. The median ILCRs for 3 carcinogenic OPEs are all less than 10-6, suggesting no cancer risk induced by these compounds for both adults and children. This review helps to understand the composition, spatial pattern and human exposure risk of OPEs and NBFRs in indoor dust worldwide.

Occurrence, source apportionment, and ecological risk assessment of organophosphate esters in surface sediment from the Ogun and Osun Rivers, Southwest Nigeria

Organophosphate esters (OPEs) are synthetic chemicals widely used as e.g., flame retardants and plasticisers in various consumer products. Due to the toxicity of OPEs in aquatic ecosystems, exposure of fauna and flora to these compounds is of potential concern. In this study, the concentrations, profiles, sources, and ecological risk of eight OPEs were investigated in the sediments from the two major rivers in southwest Nigeria. Concentrations of ∑OPEs in surface sediments were in the range 13.1 - 2110 ng/g dry weight (dw) (median: 378 ng/g dw) in the Ogun River and 24.7-589 ng/g dw (median: 174 ng/g dw) in the Osun River. These concentrations are broadly within the range of those reported in surface sediment in previous studies conducted in other locations around the world. Tris (2-butoxyethyl) phosphate (TBOEP) was the dominant OPE in the sediment samples with a median concentration of 337 and 126 ng/g dw for the Ogun and Osun Rivers respectively, while tri-n-butyl phosphate (TnBP) was not detected in any sample. Excluding TBOEP, the chlorinated organophosphate esters: tris(2-chloroethyl) phosphate (TCEP), tris(2-chloro-propyl) phosphate (TCIPP), and tris(1,3-dichloro-2-propyl) phosphate (TDCIPP) were the dominant OPEs in the Osun River, while the aryl-OPEs: triphenyl phosphate (TPHP), 2-ethylhexyl diphenyl phosphate (EHDPP), and tri-m-tolyl phosphate (TMTP) were dominant in the Ogun River. Under a median exposure scenario, moderate ecological risk was predicted from exposure to TCIPP in the Osun River. In contrast, under a high exposure scenario, concentrations of TDCIPP (risk quotient, RQ = 5.33-5.37) constituted a high ecological risk in both rivers, with moderate risks observed for TBOEP (RQ = 0.022-0.18) and TCIPP (RQ = 0.097 - 0.16). Therefore, the risk to aquatic organisms from concomitant exposure to mixtures of OPEs in freshwater ecosystems requires further investigation.

Exposure to organophosphate flame retardants and plasticizers is positively associated with wheeze and FeNO and eosinophil levels among school-aged children: The Hokkaido study

Exposure to organophosphate flame retardants and plasticizers (PFRs) increases the risk of asthma and allergies. However, little is known about its association with type 2 inflammation (T2) biomarkers used in the management of allergies. The study investigated associations among urinary PFR metabolite concentrations, allergic symptoms, and T2 biomarkers. The data and samples were collected between 2017 and 2020, including school children (n = 427) aged 9-12 years living in Sapporo City, Japan, among the participants of "The Hokkaido Study on Environment and Children's Health." Thirteen urinary PFR metabolites were measured by LC-MS/MS. Allergic symptoms were assessed using the International Study of Asthma and Allergies in Childhood questionnaire. For T2 biomarkers, the peripheral blood eosinophil counts, fraction of exhaled nitric oxide level (FeNO), and serum total immunoglobulin E level were measured. Multiple logistic regression analysis, quantile-based g-computation (qg-computation), and Bayesian kernel machine regression (BKMR) were used to examine the associations between the health outcomes of the individual PFRs and the PFR mixtures. The highest concentration of PFR was Σtris(1-chloro-isopropyl) phosphates (ΣTCIPP) (Median:1.20 nmol/L). Tris(1,3-dichloro-2-propyl) phosphate (TDCIPP) was significantly associated with a high odds ratio (OR, 95%CI:1.36, 1.07-1.72) for wheeze. TDCIPP (OR, 95%CI:1.19, 1.02-1.38), Σtriphenyl phosphate (ΣTPHP) (OR, 95%CI:1.81, 1.40-2.37), and Σtris(2-butoxyethyl) phosphate (ΣTBOEP) (OR, 95%:1.40, 1.13-1.74) were significantly associated with increased odds of FeNO (≥35 ppb). ΣTPHP (OR, 95%CI:1.44, 1.15-1.83) was significantly associated with high eosinophil counts (≥300/μL). For the PFR mixtures, a one-quartile increase in all PFRs (OR, 95%CI:1.48, 1.18-1.86) was significantly associated with high FeNO (≥35 ppb) in the qg-computation model. The PFR mixture was positively associated with high FeNO (≥35 ppb) and eosinophil counts (≥300/μL) in the BKMR models. These results may suggest that exposure to PFRs increases the probability of asthma, allergies, and T2 inflammation.

Exposure to dust organophosphate and replacement brominated flame retardants during infancy and risk of subsequent adverse respiratory outcomes

BACKGROUND

Children are highly exposed to flame retardants in indoor environments, partly through inhalation. However, the associations of early life exposure to novel organophosphate (OPFRs) and replacement brominated flame retardants (RBFRs) with adverse respiratory outcomes during childhood are unclear.

METHODS

We used a prospective birth cohort of 234 children recruited from the greater Cincinnati, Ohio metropolitan area between 2003 and 2006. OPFRs and RBFRs were analyzed in dust sampled from the homes' main activity room and the children's bedroom floor at child age 1 year. Caregivers reported subsequent respiratory symptoms every six months until child age 5 years and we measured forced expiratory volume in 1 s as well as peak expiratory flow (PEF) at child age 5 years. We performed generalized estimating equations and linear regression modeling adjusted for covariates to examine the exposure-outcome associations.

RESULTS

Geometric means (GMs) (standard error [SE]) for dust concentrations were 10.27 (0.63) μg/g for total OPFRs (ΣOPFRs) and 0.48 (0.04) μg/g for total RBFRs (ΣRBFRs); GMs (SE) for dust loadings were 2.82 (0.26) μg/m2 for ΣOPFRs and 0.13 (0.01) μg/m2 for ΣRBFRs. Dust ∑OPFRs concentrations at age 1 year were associated with higher subsequent risks of wheezing (relative risk [RR]: 1.68, 95% confidence interval [CI]: 1.20-2.34), respiratory infections (RR: 4.01, 95% CI: 1.95-8.24), and hay fever/allergies (RR: 1.33, 95% CI: 1.10-1.60), whereas ∑OPFRs dust loadings at age 1 year were associated with higher risks of subsequent respiratory infections (RR: 1.87, 95% CI: 1.05-3.34) and hay fever/allergies (RR: 1.34, 95% CI: 1.19-1.51). PEF (mL/min) was lower with higher ∑OPFRs dust loadings (β: -12.10, 95% CI: -21.10, -3.10) and with the RBFR bis(2-ethylhexyl) tetrabromophthalate (β: -9.05, 95% CI: -17.67, -0.43).

CONCLUSIONS

Exposure to OPFRs and RBFRs during infancy may be a risk factor for adverse respiratory outcomes during childhood.

Sex-specific effects of organophosphate ester exposure on child growth trajectories in the first two years

The connections between urinary organophosphate ester (OPE) metabolites and child growth have been identified in prior research, but there is currently a dearth of epidemiological evidence regarding the sex-specific impact of OPEs on child growth trajectories. This study enrolled 804 maternal–child pairs, and five OPE congeners were quantified in maternal serum during pregnancy. In this study, the impact of prenatal OPE exposure on child growth trajectories was assessed using linear mixed-effect models and a group-based trajectory model (GBTM), with consideration given to sex-specific effects. Fetuses were frequently exposed to OPEs in utero, and tris(2-butoxyethel) phosphate (TBEP) exhibited the highest concentration levels in maternal serum. Among male children, an increase of 2.72 ng/g lipid in TBEP concentration was associated with a 0.11-unit increase in head circumference-for-age z-score (HCAZ), and the effect was mainly concentrated at 1 and 2 months of age. Among female children, an increase of 2.72 ng/g lipid in tris(2-chloro-1-(chloromethyl) ethyl) phosphate (TDCPP) concentration was associated with a 0.15-unit increase in length-for-age z-score (LAZ) and a 0.14-unit increase in weight-for-age z-score (WAZ), and the effects were mainly concentrated at 9 months of age. For HCAZ trajectories, higher prenatal TBEP exposure was associated with higher odds for the fast growth group in male children. For the LAZ and WAZ trajectories, higher prenatal TDCPP exposure was associated with higher odds for the fast growth group in female children. The trajectory analysis approach provided insight into the complex associations between OPE exposure and child growth.

•Organophosphate ester (OPEs) were detected in serum samples of pregnant women, and tributyl phosphate (TBP) was the most frequently detected OPEs. •Prenatal exposure to TBP, tris(2-butoxyethyl) phosphate (TBEP), and tris(2-chloro-1-(chloromethyl) ethyl) phosphate (TDCPP) were positively associated with infant growth trajectories. •Female infants were more sensitive to OPE exposure than males.

First insight into the sex-dependent accumulation, tissue distribution and potential toxicities of 2-ethylhexyl diphenyl phosphate and its metabolites in adult zebrafish

The 2-ethylhexyl diphenyl phosphate (EHDPHP), a primary organophosphorus flame retardant used in various industrial products, is prone to biotransformation. However, there is a knowledge gap on the sex- and tissue-specific accumulation and potential toxicities of EHDPHP (M1) and its metabolites (M2-M16). In this study, adult zebrafish (Danio rerio) were exposed to EHDPHP (0, 5, 35 and 245 µg/L) for 21-day, which was followed by 7-day depuration. The bioconcentration factor (BCF) of EHDPHP in female zebrafish was 26.2 ± 7.7% lower than in males due to the lower uptake rate (k_u) while higher depuration rate (k_d) in the females. The regular ovulation and higher metabolic efficiency promoted elimination from female zebrafish, thus leading to much less (28-44%) accumulation of ∑(M1-M16) in female zebrafish. They exhibited the highest accumulation in the liver and intestine in both sexes, which might be regulated by tissue-specific transporters and histones evidenced by molecular docking results. Intestine microbiota analysis further revealed that female zebrafish were more susceptible to EHDPHP exposure, with more significant changes in phenotype number and KEGG pathways in female than male fish. Disease prediction results suggested that EHDPHP exposure might cause cancers, cardiovascular diseases as well as endocrine disorders in both sexes. These results provide a comprehensive understanding of the sex-dependent accumulation and toxicity of EHDPHP and its metabolites.

Exposures to Organophosphate Esters and Respiratory Morbidity among School-Aged Children with Asthma

Organophosphate esters (OPEs) are an emerging class of chemicals used in a variety of consumer products as flame retardants, plasticizers, and additives. While prior epidemiologic studies suggest that OPEs may impact respiratory health, results remain inconclusive. We examined associations between urinary biomarkers of OPEs and symptoms of respiratory morbidity in a panel study of 147 predominantly Black school-aged children with asthma living in Baltimore City, Maryland. The study consisted of up to four seasonal, week-long, in-home visits where urine samples and self-reported asthma symptoms were collected on days 4 and 7 (n_samples = 438). We quantified concentrations of nine urinary OPE biomarkers: bis(2-chloroethyl) phosphate (BCEtp), bis(1-chloro-2-propyl) phosphate (BCPP), bis(1,3-dichloro-2-propyl) phosphate (BDCIPP), di-n-butyl phosphate (DBuP), di-benzyl phosphate (DBzP), di-o-cresylphosphate (DOCP), di-p-cresylphosphate (DPCP), di-(2-propylheptyl) phthalate (DPHP), and 2,3,4,5-tetrabromo benzoic acid (TBBA). We estimated prevalence odds ratios (POR) of respiratory morbidity symptoms using logistic regression with generalized estimating equations to account for our repeated measure design. We assessed BDCIPP and DPHP as continuous (log₂) concentrations and dichotomized exposure of BCEtP, DBuP, and DPCP (detect vs non-detect) based on their lower detection frequencies. We adjusted models for season, visit day, age, gender, caregiver education, health insurance type, exposure to household smoking, atopy, and PM_2.5. Higher DPHP concentrations were significantly associated with odds of daytime symptoms (POR: 1.26; 95% CI: 1.04-1.53; p = 0.02) where daytime symptoms consisted of trouble breathing due to asthma, reporting bother caused by asthma, and/or limitation in activities due to asthma. DBuP detection was associated with use of rescue medication on the day of sample collection (POR: 2.36; 95% CI: 1.05-5.29; p = 0.04). We also observed several consistent, albeit non-significant (p > 0.05), positive associations for BCEtP and DPCP and respiratory morbidity measures. This is the first study to evaluate the relationship between OPE biomarkers and respiratory morbidity symptoms in children with asthma, and findings suggest that further studies are warranted to confirm whether these associations are causal.

Organophosphate Flame Retardants in Pregnant Women: Sources, Occurrence, and Potential Risks to Pregnancy Outcomes

Organophosphate flame retardants (OPFRs) are found in various environmental matrixes and human samples. Exposure to OPFRs during gestation may interfere with pregnancy, for example, inducing maternal oxidative stress and maternal hypertension during pregnancy, interfering maternal and fetal thyroid hormone secretion and fetal neurodevelopment, and causing fetal metabolic abnormalities. However, the consequences of OPFR exposure on pregnant women, impact on mother-to-child transmission of OPFRs, and harmful effects on fetal and pregnancy outcomes have not been evaluated. This review describes the exposure to OPFRs in pregnant women worldwide, based on metabolites of OPFRs (mOPs) in urine for prenatal exposure and OPFRs in breast milk for postnatal exposure. Predictors of maternal exposure to OPFRs and variability of mOPs in urine have been discussed. Mother-to-child transmission pathways of OPFRs have been scrutinized, considering the levels of OPFRs and their metabolites in amniotic fluid, placenta, deciduae, chorionic villi, and cord blood. The results showed that bis(1,3-dichloro-2-propyl) phosphate (BDCIPP) and diphenyl phosphate (DPHP) were the two predominant mOPs in urine, with detection frequencies of >90%. The estimated daily intake (EDI_M) indicates low risk when infants are exposed to OPFRs from breast milk. Furthermore, higher exposure levels of OPFRs in pregnant women may increase the risk of adverse pregnancy outcomes and influence the developmental behavior of infants. This review summarizes the knowledge gaps of OPFRs in pregnant women and highlights the crucial steps for assessing health risks in susceptible populations, such as pregnant women and fetuses.

Gestational organophosphate ester exposure and preschool attention-deficit/hyperactivity disorder in the Norwegian Mother, Father, and Child cohort study

BACKGROUND

Attention-deficit/hyperactivity-disorder (ADHD) is a leading neurodevelopmental disorder in children worldwide; however, few modifiable risk factors have been identified. Organophosphate esters (OPEs) are ubiquitous chemical compounds that are increasingly prevalent as a replacement for other regulated chemicals. Current research has linked OPEs to neurodevelopmental deficits. The purpose of this study was to assess gestational OPE exposure on clinically-assessed ADHD in children at age 3 years.

METHODS

In this nested case-control study within the Norwegian Mother, Father, and Child Cohort study, we evaluated the impact of OPE exposure at 17 weeks' gestation on preschool-age ADHD. Between 2007 and 2011, 260 ADHD cases were identified using the Preschool Age Psychiatric Assessment and compared to a birth-year-stratified control group of 549 children. We categorized bis(2-butoxyethyl) phosphate (BBOEP) and bis(1,3-dichloro-2-propyl) phosphate (BDCIPP) as values < limit of detection (LOD) (BBOEP N = 386, BDCIPP N = 632), ≥LOD but < limit of quantification (LOQ) (BBOEP N = 413; BDCIPP N = 75), or above LOQ (BBOEP N = 70; BDCIPP N = 102). Diphenyl phosphate (DPhP) and di-n-butyl phosphate (DnBP) were categorized as quartiles and also modeled with a log10 linear term. We estimated multivariable adjusted odds ratios (ORs) using logistic regression and examined modification by sex using an augmented product term approach.

RESULTS

Mothers in the 3rd DnBP quartile had 1.71 times the odds of having a child with ADHD compared to the 1st quartile (95%CI: 1.13, 2.58); a similar trend was observed for log10 DnBP and ADHD. Mothers with BDCIPP ≥ LOD but < LOQ had 1.39 times the odds of having a child with ADHD compared to those with BDCIPP < LOD (95%CI: 0.83, 2.31). Girls had lower odds of ADHD with increasing BBOEP exposure (log10 OR: 0.55 (95%CI: 0.37, 0.93), however boys had a weakly increased odds (log10 OR: 1.25 (95%CI: 0.74, 2.11) p-interaction = 0.01].

CONCLUSIONS

We found modest increased odds of preschool ADHD with higher DnBP and BDCIPP exposure.

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.

Occurrence of organophosphorus esters in outdoor air fine particulate matter and comprehensive assessment of human exposure: A global systematic review

Organophosphate esters (OPEs) are widely used in various industrial items, including plastics, textiles, construction materials, electronics, and auto parts. Several studies have investigated the concentration of OPE compounds in the air, where different compounds have been measured. This systematic review aims to investigate and summarize the relationship between exposure concentrations of OPEs in outdoor air and health risk for different OPE compounds, and correlations between OPE compounds in emission sources. PubMed, Scopus, Embase, Web of Science, and Google Scholar were searched from January 2000 to September 2021 to identify relevant research. The quality of the studies was assessed using the OHAT risk of bias tool. Spearman's correlation and principal component analysis (PCA) were used to analyze the results and correlation between OPE compounds. A total of 7669 manuscripts were found from the search in 5 databases. Finally, 46 studies were included in the systematic review. According to the median concentrations in the studies that were included, Tris(1-chloro-2-propyl) phosphate (TCIPP) (25%), trimethylphenyl phosphate(TMPP) (19%), Tri-iso-butyl phosphate (TiBP) (12%), Triphenyl phosphate (TPHP) (9%) and Tris(2-chloroethyl) phosphate (TCEP) (8%) had the greatest concentrations of OPEs overall. The cumulative contribution of the two main factors, F1 and F2, from the principal component analysis (PCA) results is 49.81%. The EDI value for the compounds is TCEP > TCIPP > TiBP > TMPP > 2-Ethylhexyl diphenyl phosphate (EHDPP) > TPHP > Tri(2-Ethylhexyl) phosphate (TEHP) > Tri-m-cresyl phosphate (mTCP) > Tris(1, 3-dichloro-isopropyl) phosphate (TDCPP) > Tri-n-butyl phosphate (TnBP). The total amount of non-carcinogenic risk (HQ) was for children > infants > adults. The highest value of HQ was for TCEP, TCIPP, and TMPP, respectively. The highest carcinogenic risk value was for TCEP and TMPP.

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

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

The associations between renal disease severity and exposure to organophosphate flame retardants in patients with chronic kidney disease

Organophosphate flame retardants (OPFRs) are emerging and widespread environmental pollutants with potential health hazards, including nephrotoxicity. However, the exposure patterns and nephrotoxic potential of OPFRs are yet to be investigated in patients with chronic kidney disease (CKD). We conducted a cross-sectional study involving 166 patients with CKD stratified by estimated glomerular filtration rate (eGFR) and severity of proteinuria. The urinary concentrations of 10 OPFR compounds were measured to evaluate the exposure patterns. Clinical and urinary OPFR profiles were compared among subgroups to identify whether the OPFR compounds were independently correlated with eGFR and proteinuria. Additionally, lifestyle factors were compared among subgroups stratified by median concentrations of urinary OPFR compounds associated with renal disease severity. This study revealed universal exposure to OPFRs in the CKD population, with an overall urinary detection rate of 98.80 %. Furthermore, after adjusting for covariates, the urinary concentration of bis(2-chloroethyl) phosphate (BCEP) was identified as an independent predictor of lower eGFR (low vs high eGFR, odds ratio (OR) (95 % confidence interval (CI)), 1.761 (1.032-3.005) per log μg/g creatinine, p = 0.038), and the urinary concentration of bis(2-butoxyethyl) phosphate (BBOEP) was independently correlated with overt proteinuria in CKD patients (with vs without overt proteinuria, OR (95 % CI), 1.813 (1.065-3.086) per log μg/g creatinine, p = 0.028). Moreover, frequent seafood consumption was negatively correlated with urinary BCEP concentration (high vs low BCEP, OR (95 % CI), 0.455 (0.228-0.908), p = 0.025), and age was inversely associated with urinary BBOEP concentration (high vs low BBOEP, OR (95 % CI), 0.968 (0.937-0.999) per year, p = 0.048). In conclusion, our investigation highlights the extensive exposure to OPFRs and the independent association between renal disease severity and urinary BCEP/BBOEP concentrations in the CKD population, indicating the nephrotoxic potential of these pollutants.

Exposure to organophosphorus compounds of Japanese children and the indoor air quality in their residences

Several organophosphorus compounds such as organophosphate pesticides (OPPs) and trialkylphosphates (TAPs) are suspected to inhibit cholinesterase activities, to affect endocrine systems or to possibly be carcinogenic. To evaluate their adverse effects on health with chronic exposure in the general population, especially in children, we measured the household exposure to OPPs and TAPs by Japanese children via all exposure pathways and the contribution of indoor air quality. First-morning void urine was collected from subjects aged 6 to 15 years (n = 132), and airborne organophosphorus compounds were sampled in the subject's bedroom for 24 h. Airborne levels of nine OPPs and three TAPs and their urinary metabolites were determined. No significant correlations were detected for any compounds between their airborne concentrations and the urinary excretion amounts of their corresponding metabolites. The estimated daily intakes were as follows (median, μg/kg b.w./d): chlorpyrifos, 0.042; diazinon, 0.067; tri-n-butylphosphate, 0.094. The 95th percentiles of the intakes for fenthion, fenitrothion and the above three compounds did not exceed their reference limit values, although one subject had a daily intake of tri-n-butylphosphate that was about twice its reference limit value. The concentration levels of the urinary metabolite of tri-n-butylphosphate in our subjects tended to be higher than those for children in many other countries. The fractions of the amounts absorbed by inhalation to the amounts absorbed via all of the exposure pathways was only 2.3 % (median) for tri-n-butylphosphate. Inhalation did not seem to contribute very much as an absorption pathway of the organophosphorus compounds in these Japanese children while they were at home. The exposure amounts of OPPs were not suggested to be high enough to adversely affect the health of these children at present on the basis of their daily intakes compared to their reference limit values.

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

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

Impact of environmental factors and bacterial interactions on dust mite allergens in different indoor dust

Indoor dust is the main carrier of indoor pollutants, especially dust mite allergens and bacteria, they can trigger asthma, rhinitis, eczema and other allergic diseases. However, the interactions between dust mite allergens and bacterial communities in different types of indoor dust are not clear. The study focused on particulate and flocculent fibrous dust, explored the concentrations of Der p 1 (Dermatophagoides pteronyssinus) and Der f 1 (D. farinae) in 46 households in Changchun and their environmental influences, characterized the bacterial communities by high-throughput sequencing, and the interactions between Der p 1, Der f 1 and bacterial communities were explored. The results showed that Der p 1 and Der f 1 tended to accumulate more in flocculent fibrous dust, and Der p 1 predominated in the indoor dust samples. The floor height, years of housing occupancy and the living areas all affected the concentrations of dust mite allergens. In bacterial community, Proteobacteria, Firmicutes and Actinobacteria were leading phyla in the two types of dust. Kocuria, Blastococcus and Massilia were dominating genera in particulate dust and Acinetobacter, Lactobacillus, Corynebacterium_1 were dominating genera in flocculent fibrous dust. The overall diversity and species richness of bacteria in particulate dust were significantly higher than those in flocculent dust (p < 0.001). The living area was an important environmental factor affecting the bacterial community in flocculent fibrous dust (p < 0.01). The interaction between the relative abundance of Proteobacteria, Firmicutes and Actinobacteria and dust mite allergen concentrations significantly differed between the two dust types, indicating that bacteria could be used both as food and to establish symbiotic relationships with household dust mites (HDMs) hosts and provide nutrition.

Percutaneous absorption and exposure risk assessment of organophosphate esters in children's toys

The percutaneous penetration and exposure risk of organophosphate esters (OPEs) from children's toys remains largely unknown. Percutaneous penetration of OPEs was evaluated by EPISkin™ model. Chlorinated OPEs (Cl-OPEs) and alkyl OPEs, except tris(2-ethylhexyl) phosphate, exhibited a fast absorption rate and good dermal penetration ability with cumulative absorptions of 57.6-127 % of dosed OPEs. Cumulative absorptions of OPEs through skin cells were inversely associated with their molecular weight and log octanol-water partition coefficient. Additionally, a quantitative structure-activity relationship model indicated that topological charge and steric features of OPEs were closely related to the transdermal permeability of these chemicals. With the clarification of the factors affecting the transdermal penetration of OPEs, the level and exposure risk of OPEs in actual toys were studied. The summation of 18 OPE concentrations in 199 toy samples collected from China ranged from 6.82 to 228,254 ng/g, of which Cl-OPEs presented the highest concentration. Concentrations of OPEs in toys exhibited clear type differences. Daily exposure to OPEs via dermal, hand-to-mouth contact, and mouthing was evaluated, and dermal contact was a significant route for children's exposure to OPEs. Hazard quotients for noncarcinogenic risk assessment were below 1, indicating that the health risk of OPEs via toys was relatively low.

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

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

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

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

Environmental, Health, and Legislation Considerations for Rational Design of Nonreactive Flame-Retardant Additives for Polymeric Materials: Future Perspectives

Increasing polymer usage has demanded functional additives that decrease fire hazards for end users. While traditional flame-retardant (FR) additives, such as halogenated, phosphorus, and metal hydroxides, greatly reduce flammability and associated fire hazards, research has continually exposed a litany of health and environmental safety concerns. This perspective aims to identify the key components of a successful FR additive and address material, environmental, and health concerns of existing additives. Legislation surrounding FRs and persistent organic pollutants is also discussed to highlight political perception that has resulted in the increased chemical regulations and subsequent banning of FR additives. Finally, future directions of this field regarding nonreactive additives, focusing on the use of bioinspired materials and transition metal chemistries to produce alternatives for polymers with efficacies surpassing traditional additives are presented.

Allergies caused by textiles: control, research and future perspective in the medical field

Textile production forms one of the most polluting industries worldwide. However, other than damaging environmental effects, chemical waste products, such as formaldehyde or thiazolinone, are problematic for human health, as allergic potential is present in these compounds. Mostly, contact dermatitis occurs when human skin is exposed to textiles. Moreover, non-eczemous variants are mainly associated to textiles. In order to diagnose the possible allergy of the patient towards these compounds, in vivo and in vitro methods ca be performed, such as patch testing or cytokine detection assays, respectively. Newest research focuses on medical textiles such as garments or sutures to help in diagnosis, therapy and recovery of the patients. Sutures and dressings with antimicrobial properties, with the release of oxygen and growth factors offer greater properties. In this review, state of the art in the field as well as future perspectives will be discussed, which are based on the smart textiles that are going to become more important and probably widespread after the current limits exceeded.

Alkyl organophosphate flame retardants (OPFRs) induce lung inflammation and aggravate OVA-simulated asthmatic response via the NF-кB signaling pathway

Alkyl organophosphate flame retardants (OPFRs), tri-n-butyl phosphate (TnBP) and tris(2-butoxyethyl) phosphate (TBOEP), are ubiquitously detected in indoor and outdoor environments and their inhalation may result in lung damage. This study examined pulmonary toxicity after exposure to TnBP or TBOEP and investigated aggravation of inflammation and immunoreaction by TnBP in an ovalbumin (OVA)-induced mice model. Transcriptomics were used to further reveal the underlying mechanism. Exposure to TnBP or TBOEP resulted in pathological damage, including edema and thickened alveolar septum. In comparison with the control, enhanced levels of superoxide dismutase (SOD) (p < 0.01 in TnBP (High) group and p < 0.05 in TBOEP (High) group), glutathione peroxidase (GSH-px) (p < 0.05), malondialdehyde (MDA) (p < 0.01), and cytokines under a dose-dependent relationship were noted, and the expression of the Fkbp5/Nos3/MAPK/NF-кB signaling pathway (p < 0.01) was upregulated in the TnBP and TBOEP groups. Moreover, the combined exposure of TnBP and OVA exacerbated the allergic inflammatory response, including airway hyperresponsiveness, leukocytosis, cellular exudation and infiltration, secretion of inflammatory mediators, and higher expression of IgE (p < 0.01). Transcriptomics results demonstrated that the PI3K/Akt/NF-кB signal pathway was involved in TnBP-aggravated asthmatic mice. Exposure to TnBP or TBOEP resulted in oxidative damage and leukocyte-induced lung injury. TnBP can further facilitate OVA-induced asthma through an inflammatory response. This study is the first to reveal the pulmonary toxicity and potential mechanism induced by OPFRs through an in-vivo model.

Exposure to organophosphate esters in elderly people: Relationships of OPE body burdens with indoor air and dust concentrations and food consumption

Human exposure to OPEs is pervasive and should be of great concern due to associations with adverse health effects, especially in susceptible populations. In this study, body burdens and exposure pathways of OPEs were investigated for 76 healthy elderly people in Jinan, China based on the measured OPE and metabolite concentrations in human bio-samples (whole blood and urine) and paired environmental matrices (air and dust), as well as food frequency questionnaire. Eight of 16 OPEs and 5 of 11 metabolites were detected in > 50% of whole blood and urine samples, respectively. Tri(1-chloro-2-propyl) phosphate (TCIPP), tris(2-chloroethyl) phosphate (TCEP), tri-phenyl phosphate (TPHP), and 2-ethylhexyl di-phenyl phosphate (EHDPP) were frequently detected and abundant in whole blood, while their corresponding metabolites were detected at low frequencies or levels in urine. The reduced metabolic and/or excretory capacity of elderly people may be an important reason, implying a higher health risk to them. Fourteen OPEs had over 50% detection frequencies in indoor air and dust, while 6 di-esters in indoor dust. Tris(2-ethylhexyl) phosphate (TEHP) in indoor dust and tri-n-butyl phosphate (TnBP) in indoor air were positively correlated with paired levels in blood but not with their metabolites (BEHP and DnBP) in urine. Combined with the direct intakes of BEHP and DBP from dust, blood is indicated as more suitable biomarker for TEHP and TnBP exposure. High consumption frequencies of several foods were associated with higher blood concentrations of three OPEs and urinary levels of four di-OPEs, indicating the importance of dietary exposure pathway. Estimated daily total intakes of OPEs via inhalation, dust ingestion, and dermal absorption ranged from 2.78 to 42.0 ng/kg bw/day, which were far less than the reference dosage values. Further studies were warranted to explore the potential health effects of OPE exposure in the elderly populations.

Human internal exposure to organophosphate esters: A short review of urinary monitoring on the basis of biological metabolism research

As alternatives to traditional brominated flame retardants, organophosphate flame retardants (OPFRs), especially for organophosphate esters (OPEs) -- the most widely used and investigated OPFRs, have raised people's concern on their environmental and health-related risks over the years. Considering their extensive environmental occurrence and potential adverse effects, precise estimation on the human body burden of OPEs will be conducive to the restrictions on the usage of these compounds scientifically. Biomonitoring research can provide precise information on human exposure to OPEs as it reveals the degree of external exposure from all exposure routes. Knowledge on biotransformation and metabolism of OPEs in the biosystems is of great significance for our understanding of the internal exposure to these compounds. In this study, the biological metabolic processes of nine OPEs prevalent in the environment, involving tris(2-chloroethyl) phosphate (TCEP), tris(1-chloro-2-propyl) phosphate (TCIPP), tris(1,3-dichloro-2-propyl) phosphate (TDCIPP), tripropyl phosphate (TPrP), tri-n-butyl phosphate (TnBP), tris(2-butoxyethyl) phosphate (TBOEP), triphenyl phosphate (TPhP), 2-ethylhexyl diphenyl phosphate (EHDPP), and tricresyl phosphate (TCrP), are comprehensively reviewed. Specifically, the metabolic pathway, kinetics and mechanism of OPEs are depicted in detail. Under this context, the advances and limitations on biomonitoring of OPE metabolites in human urine are summarized. The requirements of specificity, quantitative stability, high detection frequency/concentration are needed for OPE metabolites to be considered and validated as biomarkers. Thus far, deeper elucidations on the metabolic processes and identification of biomarkers of OPEs are urgently required, given that some OPEs have no suitable biomarkers in human biomonitoring. For better assessment of the body burden of OPEs in humans, reliable and effective methodologies for urine sampling and estimation on internal exposure to OPEs need to be further developed in the future.

Association of exposures to perchlorate, nitrate, and thiocyanate with allergic symptoms: A population-based nationwide cohort study

Allergic diseases have been one of the leading causes of chronic disorders in the United States. Animal studies have suggested that exposures to perchlorate, nitrate, and thiocyanate could induce allergic inflammation. However, the associations have not been examined among general populations. Here, we investigated data of 7030 participants aged ≥6 years from the National Health and Nutritional Examination Survey (NHANES) 2005-2006. Urinary levels of perchlorate, nitrate, and thiocyanate were measured by ion chromatography combined with electrospray tandem mass spectrometry. Information on allergic symptoms (hay fever, allergy, rash, sneeze, wheeze, eczema, and current asthma) was collected by questionnaire. Allergic sensitization was defined by a concentration ≥150 kU/L for total immunoglobulin E (IgE) levels. The associations were estimated using multivariate-adjusted logistic regression models. A positive association was observed for urinary nitrate and eczema (p < 0.001 for the trend). Compared with quartile 1 (lowest quartile), the odds ratios of eczema with 95% confidence intervals [ORs (95% CIs)] from quartiles 2 to 4 were 1.72 (95% CI, 1.41, 2.09), 1.94 (1.53, 2.47) and 2.10 (1.49, 2.97) for urinary nitrate. In addition, urinary thiocyanate was positively related to sneeze (OR_{Q4 vs. Q1}: 1.25, 95% CI: 1.01, 1.55; p = 0.015 for the trend). However, urinary perchlorate was not correlated with any allergic-related outcome. Additionally, the associations were different among subgroups in a four-level polytomous model. Thus, our results suggested that exposures to nitrate and thiocyanate may be associated with allergic symptoms. Further investigations are warranted to concentrate on the practical strategies to monitor exposure levels and the latent mechanisms of the relationship between exposure and allergy.

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.

Do flame retardant concentrations change in dust after older upholstered furniture is replaced?

Upholstered furniture has been a major source of chemical flame retardant (FR) exposures in US homes since the 1970s. FRs are a large group of chemicals, many of which are associated with adverse health effects, including cancer, reproductive toxicity, and neurotoxicity. California homes have some of the highest dust concentrations of FRs, due to Technical Bulletin 117 (TB117), California's outdated flammability standard for furniture foam that was generally followed across the US and Canada. In 2014, this standard was updated to a smolder standard for furniture fabric called TB117-2013, and it is no longer reliant on FRs. This update provided an opportunity to measure differences in FR dust levels in California homes before and after residents replaced older upholstered furniture, or its foam, with products that met the new standard and were expected to be FR-free. We collected dust from homes of participants who had plans to replace older upholstered furniture, or furniture foam, with FR-free options. We returned for follow-up dust collection six, 12, and 18 months following replacement. Concentrations of three polybrominated diphenyl ethers (PBDEs) (BDE-47, BDE-99, BDE-100), three chlorinated organophosphate ester FRs (tris(2-chloroethyl) phosphate (TCEP), tris(2-chloroisopropyl) phosphate (TCIPP), and tris(1,3-dichloroisopropyl) phosphate (TDCIPP)), and one aryl organophosphate ester FR triphenyl phosphate (TPHP), were widely detected in participant homes. All measured FRs decreased in nearly all homes after the older upholstered furniture was replaced. The decreases in FRs were significant in both homes that replaced entire pieces of furniture and those that replaced only the furniture foam. This study demonstrates that replacing older upholstered furniture or foam significantly reduces concentrations of a range of FRs in the home. Foam replacement offers a potentially more economic alternative that produces a lower volume of waste.

Identification of Three Novel Chloroalkyl Organophosphate Triesters in House Dust Using Halogenation-Guided Nontarget Screening Combined with Suspect Screening

Several haloalkyl organophosphate triester (OPTE) flame retardants have been restricted in some countries due to their potential health risks, but the usage of alternative haloalkyl OPTEs is of concern. In this study, we comprehensively screened for haloalkyl OPTEs in house dust using high-resolution mass spectrometry. Through halogenation-guided nontarget screening, a rare chloroalkyl OPTE, diethylene glycol bis(bis(2-chloroisopropyl)phosphate) (DEGBBCPP), was unequivocally identified (Level 1) in house dust of Beijing, North China. In addition, by screening a suspect list of 61 haloalkyl OPTEs from the EPA's CompTox Chemicals Dashboard, we tentatively identified diethylene glycol bis(bis(2-chloroethyl)phosphate) (DEGBBCEP) and ethylene bis[bis(2-chloroethyl)phosphate] (EBBCEP) (Level 2). DEGBBCPP was detected in all 45 house dust samples, and the median concentration was 98.4 ng/g (13.6-6217 ng/g), that is, approximately one-half that of tris(1,3-dichloro-2-propyl) phosphate, a traditional high-production chloroalkyl OPTE. The detection frequencies of DEGBBCEP and EBBCEP were 96% and 98%, respectively, but at relatively low median concentrations of 10.6 ng/g (from not detected to 152 ng/g) and 3.79 ng/g (from not detected to 130 ng/g), respectively. In standard house dust SRM2585, DEGBBCEP and EBBCEP were detected at 160 ± 15.7 and 1897 ± 38.8 ng/g, respectively, but DEGBBCPP was not detected. Future studies should evaluate the potential adverse health effects of these emerging flame retardants.

The risk and impact of organophosphate esters on the development of female-specific cancers: Comparative analysis of patients with benign and malignant tumors

Environmental pollution has become a concern for public health. As endocrine disruptors, organophosphate esters (OPEs) causes many diseases via human exposure. However, there is limited research on the risk of OPE exposure to female-specific cancers. Blood measurements are biomarkers for chemical exposures by their definition. Thus, in the present study, 11 OPEs were analyzed in the plasma of patients with 4 female-specific tumors. 2-Ethylhexyl diphenyl phosphate (EHDPP) was detected at the highest levels in all groups. The Spearman correlation test results showed significantly positive correlations between some OPEs in each group, which indicated that those OPEs had similar sources and/or behaved similarly in the patients of each group. However, compared with different patient groups, obvious differences in the correlation results were noted, implying the differences in the metabolism of OPEs between different groups. The results of the correlation analysis showed that EHDPP concentration was associated with the risk of breast cancer (p < 0.05), while tri-n-butyl phosphate (TNBP), tris (methylphenyl) phosphate (TMPP), triphenyl phosphate (TPHP), and EHDPP concentrations were associated with the risk of cervical cancer (p < 0.05 or p < 0.01). These findings indicated that OPEs were associated with the risk of breast and cervical cancer.

Exposure levels, determinants and risk assessment of organophosphate flame retardants and plasticizers in adolescents (14-15 years) from the Flemish Environment and Health Study

The ubiquitous use of organophosphate flame retardants and plasticizers (PFRs) in a variety of consumer products has led to widespread human exposure. Since certain PFRs are developmental and carcinogenic toxicants, detailed exposure assessments are essential to investigate the risk associated with environmental exposure levels. However, such data are still lacking for European countries. In this study, concentrations of thirteen PFR metabolites were measured in urine samples from 600 adolescents from Flanders, Belgium. 1-Hydroxy-2-propyl bis(1-chloro-2-propyl) phosphate (BCIPHIPP), diphenyl phosphate (DPHP), bis(1,3-dichloro-isopropyl) phosphate (BDCIPP), 2-hydroxyethyl bis(2-butoxyethyl) phosphate (BBOEHEP), 2-ethylhexyl phenyl phosphate (EHPHP) and 2-ethyl-5-hydroxyhexyl diphenyl phosphate (5-HO-EHDPHP) were frequently detected (>83%) in all participants. Comparisons with study populations from outside the EU showed that urinary levels of DPHP, BDCIPP and BCIPHIPP were generally within the same range. Only exposure to 2-ethylhexyl diphenyl phosphate (EHDPHP) was presumably higher in Flemish adolescents. However, determinants analysis through multivariate regression analyses did not reveal significant predictors that may explain this finding. Significantly higher levels of BDCIPP were observed in participants with new decorations at home, while adolescents with highly educated parents had higher levels of BBOEHEP and BDCIPP. Furthermore, multiple PFR metabolite concentrations followed a seasonal pattern. Estimated daily intakes (EDIs) were calculated from the internal dose by including fractions of urinary excretion (F_UE) estimated in in vitro metabolism studies. EDIs ranged from 6.3 ng/kg bw/day for TBOEP to 567.7 ng/kg bw/day for EHDPHP, which were well below the available oral reference doses for all investigated PFRs. This suggests that the associated risk is low at present. This is the first report on internal exposure to seven commonly used PFRs in a European population.

Chlorinated Flame-Retardant Dechlorane 602 Potentiates Type 2 Innate Lymphoid Cells and Exacerbates Airway Inflammation

Chlorinated flame-retardant dechloranes are emerging substitutes for restricted flame retardants. Recent studies have demonstrated that they are accumulated in wildlife and detectable in humans; however, their effects on human health are poorly understood. Here, for the first time, we revealed that widely used chlorinated flame-retardant dechlorane 602 (Dec 602) exacerbated airway inflammation in two mouse models induced by house dust mite (HDM) or IL-33, respectively. Deteriorated airway inflammation by Dec 602 was associated with a higher production of type 2 cytokines including IL-4, IL-5, and IL-13, and IgE, accompanied by enhanced mRNA expression of proinflammatory cytokines such as TNF-α and IL-6. Mechanistically, we found that Dec 602 directly potentiated mouse and human group 2 innate lymphoid cells and, as such, promoted airway inflammation even in the absence of conventional T cells in Rag ^-/- mice. These findings provide novel immunological insights necessary for further studies of the health impact of emerging flame-retardant dechloranes including Dec 602.

Short-term temporal variability of urinary biomarkers of organophosphate flame retardants and plasticizers

BACKGROUND

Exposure to organophosphate flame retardants and plasticizers (PFRs) is commonly estimated by measuring biomarker concentrations in spot urine samples. However, their concentrations in urine can vary greatly over time due to short biological half-lives and variable exposure, potentially leading to exposure misclassification. In this study, we examined the within- and between-individual and within- and between-day variability of PFR metabolites in spot and 24-hour pooled urine samples during five consecutive days.

METHODS

We collected all spot urine samples from 10 healthy adults for 5 days. On one additional day, we collected 24-hour pooled urine samples. Samples were analyzed by solid-phase extraction coupled to high-performance liquid chromatography tandem mass spectrometry. We calculated intraclass correlation coefficients (ICCs) to assess the reproducibility of metabolite concentrations in morning void and spot samples.

RESULTS

Fair-to-good reproducibility was observed for serial measurements of bis(1,3-dichloro-2-propyl) phosphate (BDCIPP), 1-hydroxy-2-propyl bis(1-chloro-2-propyl) phosphate (BCIPHIPP), 2-hydroxyethyl bis(2-butoxyethyl) phosphate (BBOEHEP) and 2-ethyl-5-hydroxyhexyl diphenyl phosphate (5-HO-EHDPHP) (ICC: 0.396 - 0.599), whereas concentrations of diphenyl phosphate (DPHP) and 2-ethylhexyl phenyl phosphate (EHPHP) were more variable in time (ICC: 0.303 and 0.234). Reproducibility improved significantly when only morning void samples were considered and when concentrations were adjusted for urinary dilution. Collecting 24-hour pooled urine could be a reliable alternative for PFR biomarkers with poor short-term temporal variability.

CONCLUSIONS

The between-day variability was minor compared to variability observed within the same day, which suggests that collecting multiple samples could reduce exposure missclassification. Differences in the observed between- and within-individual variance were compound specific and related to both the nature of the exposure (e.g., diet vs other exposure routes, multiple sources) and the individual toxicokinetic properties of the investigated PFRs.

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.

Organophosphorus-based chemical additives induced behavioral changes in zebrafish (Danio rerio): Swimming activity is a sensitive stress indicator

Organophosphorus flame retardants (OPFRs) have been extensively used as chemical additives in polymer based consumer products. Among them, Isopropylphenyl phosphate (IPPP) and tripropyl phosphate (TPP) are predominant, which have potential to cause neuro-toxic effects on non-target organisms. As behavior (swimming activity) response is the first adjustment due to neurotoxic stress on the fitness of fish. In this study, the quantified swimming activity of zebrafish (Danio rerio) under IPPP and TPP exposure in an online monitoring system was investigated to assess the neurotoxin effects under long-term exposure periods, no swimming anomalies were observed in the control group. Whereas, in the OPFR exposures ((treatment I: 5 μg/L and treatment II: 25 μg/L), a series of anomalies were identified. Hyperactivity was shown in IPPP treatment I group (5 μg/L), whereas zebrafish swimming activity was declined throughout the study period in IPPP treatment II (25 μg/L), and TPP groups (5 μg/L and 25 μg/L) when compared to the control group. Circadian rhythm was not affected in the present study. The results of the present study indicated that the fitness of test individuals was a valid biomarker for eco-toxicity assessment under unescapable conditions. Hypoactivity of zebrafish signified the neurotoxic effects of IPPP and TPP. A concentration based improvement in swimming activity was observed under recovery conditions, which suggested that recovery capacity along with toxicity responses could be a comprehensive non-invasive technique to assess the eco-toxicity of waterborne chemicals.

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.

Enantioselective disposition and metabolic products of isofenphos-methyl in rats and the hepatotoxic effects

Isofenphos-methyl (IFP), a chiral organophosphorus pesticide, is one of the main chemicals used to control underground insects and nematodes. Recently, the use of IFP on vegetables and fruits has been prohibited due to its high toxicity. In this study, we investigated the enantioselective distribution and metabolism of IFP and its metabolites, namely, isofenphos-methyl oxon (IFPO) and isocarbophos oxon (ICPO), in male Sprague Dawley (SD) rats. Forty eight hours (48 h) after exposure, ICPO was the main detectable compound in blood (up to 75%) and urine (up to 77%), and we found that (S)-ICPO was significantly more stable than (R)-ICPO (p < 0.05). Therefore, (S)-ICPO was proposed as a suitable candidate biomarker for the biomonitoring of IFP in human urine and blood. After 48 h exposure, 21.2-41.0%, 4.1-15.1%, and 8.6-18.7% of dosed IFP was detected in the liver of racemic, R and S enantiomer-exposed rats, respectively, and R-IFP and R-IFPO showed a faster degradation (p < 0.05). Our results showed that after one week of consecutive exposure to IFP, ICPO was accumulated in the liver of rats in both racemic and enantiopure groups (no difference between the groups, p > 0.05). We found that cytochrome P450 (CYP) (i.e. CYP2C11, CYP2D2 and CYP3A2 enzymes and carboxylesterases) is responsible for the enantioselective metabolism of IFP in liver. In addition, rats exposed to (S)-IFP exhibited hepatic lipid peroxidation, liver inflammation and hepatic fibrosis. This study provides useful information and a reference for the biomonitoring and risk assessment of IFP and organophosphorus pesticide exposure.

Organophosphorus Flame Retardants: A Global Review of Indoor Contamination and Human Exposure in Europe and Epidemiological Evidence

We aimed to identify high-priority organophosphorus flame retardants for action and research. We thus critically reviewed literature between 2000 and 2019 investigating organophosphorus flame retardants' presence indoors and human exposure in Europe, as well as epidemiological evidence of human effects. The most concentrated compounds indoors were tris(2-butoxyethyl)phosphate (TBOEP), tris(1-chloro-2-propyl)phosphate (TCIPP), tris(2,3-dichloropropyl)phosphate (TDCIPP). TBOEP and TCIPP were the most consistently detected compounds in humans' urine, hair or breast milk as well as tris (butyl) phosphate (TNBP) and tris (phenyl) phosphate (TPHP). Notably, epidemiological evidence concerned reprotoxicity, neurotoxicity, respiratory effects and eczema risk for TDCIPP, eczema increase for TBOEP, and neurodevelopmental outcomes for Isopropylated triarylphosphate isomers (ITPs). Given the ubiquitous presence indoors and the prevalence of exposure, the growing health concern seems justified. TDCIPP and TPHP seem to be of particular concern due to a high prevalence of exposure and epidemiological evidence. TBOEP and TNBP require epidemiological studies regarding outcomes other than respiratory or dermal ones.

Nontarget Discovery of 11 Aryl Organophosphate Triesters in House Dust Using High-Resolution Mass Spectrometry

There is growing interest in the identification of novel aryl organophosphate triester (OPTE) congeners that may exist in the environment. In this study, we discovered 11 novel aryl OPTEs in north China house dust using a characteristic aryl phosphate fragment-guided high-resolution mass spectrometry method with data-independent acquisition. Tripentylated triphenyl phosphate (TPeTPhP), dicresyl phenyl phosphate (DCrPP), diisodecylphenyl phosphate (DIDPP), butoxyethoxyethyl octyl phenyl phosphate (BEEOPP), dioctyl nonylphenyl phosphate (DONPP), propoxypropyl bis(diphenyl phosphate) (PPBDPhP), octyl nonylphenyl phenyl phosphate (ONPPP), and (saturated mono-oxygen butoxybutyl) butoxyethoxyethyl phenyl phosphate (MBBPP) were detected in 84-100% of 45 samples. ONPPP was present in the highest median concentration of 69.0 ng/g, followed by DONPP (68.7 ng/g), DIDPP (50.3 ng/g), BEEOPP (42.5 ng/g), DCrPP (33.7 ng/g), PPBDPhP (25.0 ng/g), TPeTPhP (9.28 ng/g), and MBBPP (4.80 ng/g). Seven novel aryl OPTEs were also detected in standard house dust SRM2585, and the concentration of DIDPP (4375 ± 660 ng/g) was 4-fold higher than that (1048 ± 44.5 ng/g) of triphenyl phosphate, a typical aryl OPTE. The discovery of these novel OPTEs has significantly enriched our understanding of the aryl OPTEs present in house dust.

Changes in the circRNA expression profile of PC12 cells induced by TDCIPP exposure may regulate the downstream NF-κB pathway via the Traf2 gene

As a commonly used organophosphorus flame retardant (OPFR), tris (1,3-dichloro-2-propyl) phosphate (TDCIPP) has become an environmental pollutant. Studies have shown that TDCIPP exposure has many toxic effects, such as neurotoxicity, reproductive development toxicity and endocrine disturbance. CircRNAs are circular noncoding RNAs that have been found to play important roles in the occurrence of a variety of diseases. However, it is unclear whether circRNAs play a role in the cytotoxicity induced by TDCIPP exposure. In this study, we analysed the circRNA microarray results of a control group and a TDCIPP exposure group of PC12 cells and detected 3432 differentially expressed circRNAs (P < 0.05), of which 1682 were upregulated and 1750 were downregulated in the TDCIPP-exposure group. The expression levels of 2 upregulated and 3 downregulated circRNAs were verified by real-time quantitative PCR, and the results were consistent with the microarray results. Then, ceRNA analysis was performed on several kinds of circRNAs to predict the possible binding miRNAs and binding sites. The target genes were analysed by Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis. Through predictive analysis, it was found that rno_circRNA_013845, rno-miR-361-3p, and rno-miR-702-3p may be involved in the regulation of Traf2 expression, thereby affecting the expression of the downstream NF-κB signalling pathway and causing apoptosis.