Polybrominated diphenyl ethers and novel brominated flame retardants in human milk from the general population in Beijing, China: Occurrence, temporal trends, nursing infants' exposure and risk assessment

Contamination characteristics and dietary intake risk of brominated flame retardants in fishes around a typical e-waste dismantling site in Southern China

Polybrominated diphenyl ethers (PBDEs) and their substitutes, novel brominated flame retardants (NBFRs), are ubiquitously present in the aquatic environment of electronic waste (e-waste) dismantling region, leading to their inevitable absorption and accumulation by aquatic organisms, which can be transferred to human via directly aquatic product consumption or through food chain, thereby posing potential health risks. This study focused on fish samples from Guiyu and its surrounding areas, and found the total PBDEs concentrations were 24-7400 ng/g lw (mean: 1800 ng/g lw) and the total NBFRs concentrations were 14 to 2300 ng/g lw (mean: 310 ng/g lw). Significant positive correlations were found among PBDE congeners, among different NBFRs, and between NBFRs and commercial PBDEs that they replace. ΣPBDEs and ΣNBFRs in the intestine were 620-350,000 and 91-81,000 ng/g lw (mean: 83000 and 12,000 ng/g lw, respectively), significantly exceeding those in the gills, where ΣPBDEs and ΣNBFRs were 14-37,000 and 39-45,000 ng/g lw (mean: 9200 and 2400 ng/g lw, respectively). The ΣPBDEs and ΣNBFRs showed no non-carcinogenic risks to the target population through dietary intake. Despite the significantly higher daily intake of decabromodiphenyl ethane (DBDPE) compared to decabromodiphenyl ether (BDE209), the non-carcinogenic risk associated with BDE209 remained higher than that of DBDPE. Our findings can assist researchers in understanding the presence of BFRs in aquatic organisms, inhabiting e-waste dismantling areas, and in evaluating the associated health risks posed to humans through dietary exposure.

Effects of 1, 2-bis (2,4, 6-tribromophenoxy) ethane and bis (2-ethylhexyl) tetrabromophthalate on serum metabolic and lipid profiles in male rats

This study explored the effects of 1, 2-bis (2,4, 6-tribromophenoxy) ethane (BTBPE) and bis (2-ethylhexyl) tetrabromophthalate (TBPH) on serum metabolites and lipids in male Sprague-Dawley (SD) rats. Rats were orally gavaged 250 mg/kg bw of BTBPE and 500 mg/kg bw of TBPH for 28 consecutive days. Serum samples were collected for metabolomics and lipidomics analysis. Orthogonal partial least squares discriminant analysis (OPLS-DA) was used to explore changes in rat metabolic patterns. Least absolute shrinkage and selection operator (LASSO) regression models were established using serum levels of total thyroxine (TT4), free thyroxine (FT4), and rats' grouping information as variables to screen for robust differential substances. SuperPred was the database to obtain potential targets. The metabolomics and lipidomics results showed that BTBPE and TBPH had an impact on rat metabolic patterns, affecting pathways such as vitamin B6 synthesis. For BTBPE treatment, pyridoxal and ceramide (Cer) 24:0;4O were selected as differential substances related to thyroid hormones. For TBPH treatment, dehydroascorbic acid, acylcarnitine (CAR) 19:0, and diglyceride (DG) 38:4 were selected as differential substances related to thyroid hormones. Serotonin 2c receptor and cyclooxygenase-2 were chosen as potential targets of BTBPE and TBPH, respectively. In conclusion, this study found that BTBPE and TBPH impacted the metabolism of rats, and this effect may be related to changes in thyroid function.

Mechanistic Insights into 1,2-bis(2,4,6-tribromophenoxy)ethane-Induced Male Reproductive Toxicity in Zebrafish

The novel brominated flame retardant, 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE), has increasingly been detected in environmental and biota samples. However, limited information is available regarding its toxicity, especially at environmentally relevant concentrations. In the present study, adult male zebrafish were exposed to varying concentrations of BTBPE (0, 0.01, 0.1, 1, and 10 μg/L) for 28 days. The results demonstrated underperformance in mating behavior and reproductive success of male zebrafish when paired with unexposed females. Additionally, a decline in sperm quality was confirmed in BTBPE-exposed male zebrafish, characterized by decreased total motility, decreased progressive motility, and increased morphological malformations. To elucidate the underlying mechanism, an integrated proteomic and phosphoproteomic analysis was performed, revealing a predominant impact on mitochondrial functions at the protein level and a universal response across different cellular compartments at the phosphorylation level. Ultrastructural damage, increased expression of apoptosis-inducing factor, and disordered respiratory chain confirmed the involvement of mitochondrial impairment in zebrafish testes. These findings not only provide valuable insights for future evaluations of the potential risks posed by BTBPE and similar chemicals but also underscore the need for further research into the impact of mitochondrial dysfunction on reproductive health.

Single and combined association between brominated flame retardants and cardiovascular disease: a large-scale cross-sectional study

Introduction

The single and combined association between brominated flame retardants (BFRs) and cardiovascular diseases (CVD) has remained unelucidated. This research aimed at exploring the associations between mixture of BFRs and CVD.

Methods

This research encompassed adult participants from the National Health and Nutrition Examination Survey in 2005-2016. The weighted quantile sum (WQS) model and quantile g-computation (QGC) model were applied to examine the combined effects of BFRs mixture on CVD.

Results

In this research, overall 7,032 individuals were included. In comparison with the lowest quartile, the highest quartile of PBB153 showed a positive association with CVD, with odds ratio (OR) values and 95% confidence intervals (CI) of 19.2 (10.9, 34.0). Furthermore, the acquired data indicated that PBB153 (OR: 1.23; 95% CI: 1.02, 1.49), PBB99 (OR: 1.29; 95% CI: 1.06, 1.58), and PBB154 (OR: 1.29; 95% CI: 1.02, 1.63) were linked to congestive heart failure. PBB153 was also related to coronary heart disease (OR: 1.29; 95% CI: 1.06, 1.56). Additionally, a positive correlation between the BFRs mixture and CVD (positive model: OR: 1.23; 95% CI: 1.03, 1.47) was observed in the weighted quantile sum (WQS) model and the quantile g-computation (QGC) model.

Discussion

Therefore, exposure to BFRs has been observed to heighten the risk of cardiovascular disease in US adults, particularly in the case of PBB153. Further investigation is warranted through a large-scale cohort study to validate and strengthen these findings.

Polybrominated Diphenyl Ethers in Human Milk of Croatian First-Time Mothers: 2010 Versus 2020

The presence of selected polybrominated diphenyl ethers (BDE-28, -47, -99, -100, -153, -154, and -183) was investigated in human milk samples collected from first-time mothers living in Zagreb, capital of Croatia. Samples from 2020 and 2010 were analyzed, and the first temporal comparison between the profiles and levels of these compounds in this area was obtained. A statistically significant difference between mass fractions depending on the sampling year was observed only for BDE-99, with values in 2020 higher than in 2010. BDE-153, whose median value (0.25 and 0.26 ng g-1 lipid weight (l.w.) in 2010 and 2020, respectively) did not decrease in the 10-year period, was the most frequently detected congener in samples from both years. ΣPBDEs ranged from < LOD to 3.53 ng g-1 l.w. (median 0.25 ng g-1 l.w.), and from 0.14 to 6.75 ng g-1 l.w. (median 0.55 ng g-1 l.w.) in 2010 and 2020, respectively. Maternal age and reported fish consumption had no effect on observed PBDE mass fractions, while for BDE-153, positive significant correlation (p > 0.05) was observed of its detected mass fraction with mother's body mass index (BMI) before pregnancy and after childbirth. Infants median estimated daily intake (EDI) via milk ingestion for ΣPBDE was higher in 2020 (3.221 ng kg-1 bw day-1) compared to 2010 (1.429 ng kg-1 bw day-1), but both values were well below threshold value, indicating that human milk consumption in this specific case is unlikely to raise health risks to infants.

Evidence for Adverse Effects on Liver Development and Regeneration in Zebrafish by Decabromodiphenyl Ethane

Decabromodiphenyl ethane (DBDPE), a ubiquitous emerging pollutant, could be enriched in the liver of organisms, but its effects and mechanisms on liver development and regeneration remain largely unknown. In the present study, we first investigated the adverse effects on liver development and found decreased area and intensity of fluorescence in transgenic zebrafish larvae exposed to DBDPE; further results in wild-type zebrafish larvae revealed a possible mechanism involving disturbed MAPK/Fox O signaling pathways and cell cycle arrest as indicated by decreased transcription of growth arrest and DNA-damage-inducible beta a (gadd45ba). Subsequently, an obstructed recovery process of liver tissue after partial hepatectomy was characterized by the changing profiles of ventral lobe-to-intestine ratio in transgenic female adults upon DBDPE exposure; further results confirmed the adverse effects on liver regeneration by the alterations of the hepatic somatic index and proliferating cell nuclear antigen expression in wild-type female adults and also pointed out a potential role of a disturbed signaling pathway involving cell cycles and glycerolipid metabolism. Our results not only provided novel evidence for the hepatotoxicity and underlying mechanism of DBDPE but also were indicative of subsequent ecological and health risk assessment.

Has Regulatory Action Reduced Human Exposure to Flame Retardants?

Flame retardant (FR) exposure has been linked to several environmental and human health effects. Because of this, the production and use of several FRs are regulated globally. We reviewed the available records of polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecanes (HBCDDs) in human breast milk from literature to evaluate the efficacy of regulation to reduce the exposure of FRs to humans. Two-hundred and seven studies were used for analyses to determine the spatial and temporal trends of FR exposure. North America consistently had the highest concentrations of PBDEs, while Asia and Oceania dominated HBCDD exposure. BDE-49 and -99 indicated decreasing temporal trends in most regions. BDE-153, with a longer half-life than the aforementioned isomers, typically exhibited a plateau in breast milk levels. No conclusive trend could be established for HBCDD, and insufficient information was available to determine a temporal trend for BDE-209. Breakpoint analyses indicated a significant decrease in BDE-47 and -99 in Europe around the time that regulation has been implemented, suggesting a positive effect of regulation on FR exposure. However, very few studies have been conducted globally (specifically in North America) after 2013, during the time when the most recent regulations have been implemented. This meta-analysis provides insight into global trends in human exposure to PBDEs and HBCDD, but the remaining uncertainty highlights the need for ongoing evaluation and monitoring, even after a compound group is regulated.

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.

Associations between urogenital carcinoma and DECA-BDE (BDE-209) among wild California Sea lions (Zalophus californianus) and Steller Sea lions (Eumetopias jubatus)

Urogenital carcinoma (UGC) is prevalent among California sea lions (Zalophus californianus), while less is known concerning UGC among Steller sea lions (Eumetopias jubatus). Our objective was to investigate associations between UGC and polybrominated diphenyl ethers (PBDEs) among both sea lion species. Twenty-nine California sea lions and 20 Steller sea lions were lethally removed from the Columbia River Basin, Oregon, USA between 2020 and 2021, under Section 120 of the Marine Mammal Protection Act. UGC was diagnosed through gross necropsy and histopathology. Forty PBDE congeners were analyzed in blubber, including BDE-209, a potential carcinogen. Twenty (69 %) California sea lions and one (5 %) Steller sea lion were diagnosed with UGC. All cases were identified as early stage UGC, aside from one California sea lion with more advanced stage UGC. Among California sea lions, associations between PBDEs and UGC were analyzed using logistic regression. In the adjusted model, BDE-209 (log2-transformed) was associated with increased odds of UGC [Odds Ratio (OR): 4.68, 95 % confidence interval: 1.04, 21.0, OR p-value = 0.044). This is the first study to report BDE-209 concentrations in sea lion blubber. The percentages of California and Steller sea lions diagnosed with UGC were higher than expected for wild (non-stranded) sea lions. Our results suggested blubber BDE-209 was potentially associated with UGC in California sea lions in the Columbia River Basin.

New brominated flame retardant decabromodiphenyl ethane (DBDPE) in water sediments: A review of contamination characteristics, exposure pathways, ecotoxicological effects and health risks

As an alternative to polybrominated diphenyl ethers (PBDEs), decabromodiphenyl ethane (DBDPE) has become one of the most important new brominated flame retardants (NBFRs). However, little is known about whether this emerging contaminant may has an environmental fate similar to PBDEs. Sediments are the main sink for DBDPE in the aqueous phase. Worldwide concentration data, since it was first found in sediments to date, have been collated, and the following conclusions have been drawn. (1) DBDPE concentrations in sediments have increased rapidly, often with a higher risk of contamination in source discharge areas. Compared with other countries, DBDPE contamination in China is more severe, especially in Guangdong Province, which is closely related to its being an e-waste dismantling area. (2) The amount of DBDPE in surface sediments has exceeded that of legacy brominated flame retardants (BFRs), and data recorded in sediment cores also corroborate that DBDPE is replacing decabromodiphenyl ether (BDE-209) as one of the most dominant NBFRs in the environment. (3) The exposure pathways of DBDPE include dietary intake, air or indoor dust intake, cutaneous absorption and endogenous exposure. For sediments, dietary exposure and endogenous exposure pathways need to be considered. Sediment DBDPE can enter the human body through bioenrichment such as contaminated seafood and the food chain. (4) DBDPE can exhibit neurotoxicity, thyrotoxicity, reproductive and developmental toxicity, hepatotoxicity and oxidative stress in organisms. Long-term DBDPE exposure may increase hyperthyroidism risk and inhibit normal cells activity. This review focuses on the distribution characteristics and exposure risks of DBDPE in global water sediments, providing a strong reference for environmental management and related legal policy formulation. The next steps are to focus on continuous source monitoring, process control and sediment clean-up of DBDPE. The development of sustainable water management options for waste microplastics (MPs) and e-waste spiked with DBDPE is a priority.

Brominated flame retardants in breast milk from the United States: First detection of bromophenols in U.S. breast milk

Brominated flame retardants (BFRs) are a class of compounds with many persistent, toxic, and bioaccumulative members. BFRs have been widely detected in breast milk, posing health risks for breastfeeding infants. Ten years after the phaseout of polybrominated diphenyl ethers (PBDEs) in the United States, we analyzed breast milk from 50 U.S. mothers for a suite of BFRs to assess current exposures to BFRs and the impact of changing use patterns on levels of PBDEs and current-use compounds in breast milk. Compounds analyzed included 37 PBDEs, 18 bromophenols, and 11 other BFRs. A total of 25 BFRs were detected, including 9 PBDEs, 8 bromophenols, and 8 other BFRs. PBDEs were found in every sample but at concentrations considerably lower than in previous North American samples, with a median ∑PBDE concentration (sum of 9 detected PBDEs) of 15.0 ng/g lipid (range 1.46-1170 ng/g lipid). Analysis of time trends in PBDE concentrations in North American breast milk indicated a significant decline since 2002, with a halving time for ∑PBDE concentrations of 12.2 years; comparison with previous samples from the northwest U.S region showed a 70% decline in median levels. Bromophenols were detected in 88% of samples with a median ∑12bromophenol concentration (sum of 12 detected bromophenols) of 0.996 ng/g lipid and reaching up to 71.1 ng/g lipid. Other BFRs were infrequently detected but concentrations reached up to 278 ng/g lipid. These results represent the first measurement of bromophenols and other replacement flame retardants in breast milk from U.S. mothers. In addition, these results provide data on current PBDE contamination in human milk, as PBDEs were last measured in U.S. breast milk ten years ago. The presence of phased-out PBDEs, bromophenols, and other current-use flame retardants in breast milk reflects ongoing prenatal exposure and increased risk for adverse impacts on infant development.

The effects and mechanisms of the new brominated flame retardant BTBPE on thyroid toxicity

As an alternative to octabromodiphenyl ether (octa-BDE), 1, 2-bis (2,4, 6-tribromophenoxy) ethane (BTBPE) has been widely used in a variety of combustible materials, such as plastics, textiles and furniture. Previous studies have demonstrated the thyroid toxicity of traditional brominated flame retardants for example octa-BDE clearly. Nevertheless, little is known about the thyroid toxicity of alternative novel brominated flame retardants BTBPE. In this study, it was demonstrated that BTBPE in vivo exposure induced FT4 reduction in 2.5, 25 and 250 mg/kg bw treated group and TT4 reduction in 25 mg/kg bw treated group. TG, TPO and NIS are key proteins of thyroid hormone synthesis. The results of Western blot and RT-PCR from thyroid tissue showed decreased protein levels and gene expression levels of TG, TPO and NIS as well as regulatory proteins PAX8 and TTF2. To investigate whether the effect also occurred in humans, anthropogenic Nthy-ori 3-1 cells were selected. Similar results were seen in vitro condition. 2.5 mg/L BTBPE reduced the protein levels of PAX8, TTF1 and TTF2, which in turn inhibited the protein levels of TG and NIS. The results in vitro experiment were consistent with that in vivo, suggesting possible thyrotoxic effects of BTBPE on humans. It was indicated that BTBPE had the potential interference of T4 generation and the study provided more evidence of the effects on endocrine disorders.

Investigating the adverse outcome pathways (AOP) of neurotoxicity induced by DBDPE with a combination of in vitro and in silico approaches

Current studies have shown an association between DBDPE and neurotoxicity. In this study, the adverse outcome pathway (AOP) and mechanistic analysis of DBDPE-induced neurotoxicity were explored by a combination of in vitro and in silico approaches in SK-N-SH cells. DBDPE-induced oxidative stress caused DNA strand breaks, resulting in the activation of poly (ADP-ribose) (PAR) polymerase-1 (PARP-1). Activation of PARP1 could cause toxic damage in various organ systems, especially in the nervous system. DBDPE-induced apoptosis via the caspase-dependent intrinsic mitochondrial pathway and the PARP1-dependent pathway. Activation of PARP1 by DBDPE was deemed the initiating event, thereby affecting the key downstream biochemical events (e.g., ROS production, DNA damage, membrane potential changes, and ATP reduction), which induced apoptosis. Furthermore, excessive activation of PARP1 was accompanied by the translocation of the apoptosis-inducing factor (AIF), which was associated with PARP1-dependent cell death. The inhibition of PARP1 by PJ34 reduced DBDPE-induced apoptosis and maintained cellular ATP levels. PJ34 also prevented the translocation of AIF from the mitochondria to the nucleus. These findings improve the understanding of the mechanism of DBDPE-induced neurotoxic effects and provide a theoretical basis for the ecological risk of DBDPE.

Assessment of organohalogenated pollutants in breast milk from the Czech Republic

This biomonitoring survey brings new information on the occurrence of a total of 94 organohalogenated pollutants in 231 human breast milk samples collected in 2019 and 2021 from women living in two regions of the Czech Republic (Karvina and Ceske Budejovice). This study aimed to evaluate the concentrations of 6 indicator polychlorinated biphenyls (PCBs), 10 organochlorine pesticides (OCPs), 34 halogenated flame retardants (HFRs), 29 perfluoroalkyl and polyfluoroalkyl substances (PFAS) and 15 polychlorinated naphthalenes (PCNs). PCBs, OCPs, most of HFRs and PCNs were identified/quantified by gas chromatography coupled to (tandem) mass spectrometry (GC-MS(/MS)), while PFAS, hexabromocyclododecane isomers (HBCD), brominated phenols, and tetrabromobisphenol A (TBBPA) by ultra-high performance liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS). The mean value of the sum of the 6 indicator PCBs was 123.12 nanogram per gram of lipid weight (ng g^-1 lw). Hexachlorobenzene (HCB), β-hexachlorocyclohexane (β-HCH) and p,p'-dichlorodiphenyl-dichloroethylene (p,p'-DDE) were the most abundant OCPs, detected in 100 % (mean 11.8 ng g^-1 lw), 94.8 % (mean 6.1 ng g^-1 lw) and 100 % (mean 101.5 ng g^-1 lw) of samples, respectively. PCN congeners 20, 52 and 66 were detected in <1 % of the samples. The HFRs concentrations were relatively low compared to the levels of OCP; The detection rate of polybrominated diphenyl ethers (PBDEs, # 47, 99 and 153) ranged 21-68 % with a mean concentrations of 0.34 ng g^-1 lw - 0.42 ng g^-1 lw. PFAS concentrations were also low, with perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) dominant in this group (means of 22 pg ml^-1 and 21 pg ml^-1, respectively). Our results confirmed the long-term trend of declining levels of banned POPs in Czech mothers. The amounts of PCBs and OCPs were higher in older breastfeeding primiparous women.

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.

Multi- and Transgenerational Developmental Impairments Are Induced by Decabromodiphenyl Ethane (DBDPE) in Zebrafish Larvae

A novel brominated flame retardant decabromodiphenyl ethane (DBDPE) has become a ubiquitous emerging pollutant; hence, the knowledge of its long-term toxic effects and underlying mechanism would be critical for further health risk assessment. In the present study, the multi- and transgenerational toxicity of DBDPE was investigated in zebrafish upon a life cycle exposure at environmentally relevant concentrations. The significantly increased malformation rate and declined survival rate specifically occurred in unexposed F2 larvae suggested transgenerational development toxicity by DBDPE. The changing profiles revealed by transcriptome and DNA methylome confirmed an increased susceptibility in F2 larvae and figured out potential disruptions of glycolipid metabolism, mitochondrial energy metabolism, and neurodevelopment. The changes of biochemical indicators such as ATP production confirmed a disturbance in the energy metabolism, whereas the alterations of neurotransmitter contents and light-dark stimulated behavior provided further evidence for multi- and transgenerational neurotoxicity in zebrafish. Our findings also highlighted the necessity for considering the long-term impacts when evaluating the health of wild animals as well as human beings by emerging pollutants.

Thyroid-disrupting effects caused by exposure to alternative flame retardants from groundwater contamination in rural central China

Accumulating evidence reveals that exposure to alternative flame retardants (AFRs) results in defective thyroid functions. AFRs are detectable in various environmental media in developed cities in China. However, few studies have reported the contamination levels of AFR in groundwater in rural areas, indicating an urgent need to investigate exposure of AFRs and perform health risk assessment for populations that use groundwater as the main source of drinking water. This study investigated the concentrations of AFRs in groundwater in rural areas of central China. Moreover, Nthy-ori-3-1 cells were used to determine the thyroid cytotoxicities and thyroid-interfering effects of a single AFR as well as the mixtures of AFRs based on the AFR contamination levels in real-world. The results revealed that all classes of AFRs were detectable in rural areas in central China. Dechlorane plus, hexabromocyclododecane, bromophenols (BPs), novel brominated flame retardants (NBFRs) and organophosphate flame retardants (OPFRs) exhibited spatial contamination patterns, with an average concentrations (median) of 157.89 ± 88.61 (185.47) pg/L, 0.09 ± 0.29 (not detectable) ng/L, 5.20 ± 5.92 (3.43) ng/L, 3338.11 ± 3758.78 (2836.72) pg/L, and 79.35 ± 97.19 (53.62) ng/L, respectively. The half maximal effective concentrations (EC₅₀) of BPs, OPFRs, and NBFRs ranged 98.4-4012 μM, 42.0-2506 μM, and 10.1-203.7 μM, respectively. Several AFRs exhibited more cytotoxic effects than did traditional brominated flame retardants. It is intriguing that several single AFRs and mixtures at environmentally-relevant exposure levels promoted the viability of Nthy-ori-3-1 cells. Taken together, our study demonstrates that AFRs are present in the groundwater in rural areas in central China and AFRs exhibit thyroid disrupting effects.

Potential Health Risk to Brazilian Infants by Polybrominated Diphenyl Ethers Exposure via Breast Milk Intake

Polybrominated diphenyl ethers (PBDEs) are ubiquitous flame retardants and are environmentally persistent. PBDEs show endocrine disruption, neurotoxicity, and lower birth weight in infants, and their human body burden has become a public health concern. The infants' exposure begins in the prenatal period and continues via breast milk ingestion, although, little is known about the factors that may influence this exposure. In this study, PBDE levels in Brazilian breast milk were assessed in 200 lactating women. The risk assessment of infants' exposure to PBDE was performed through the estimated daily intake (EDI) calculation. The geometric mean (GM) of ∑_PBDEs levels was 2.33 (0.14-6.05) ng/g wet weight. At least one PBDE congener was detected in the samples, and the 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) showed a 100% of detection rate (GM of 1.05 ng/g). Location of residence, maternal level education, monthly salary, and race were positively associated with PBDE levels (p < 0.05). The EDI of BDE-47 was higher in Belo Horizonte (8.29 ng/kg/day) than in Viçosa (6.36 ng/kg/day), as well as for the ∑_PBDEs (19.77 versus 12.78 ng/kg/day) (p < 0.05). Taking the high detection rate of PBDEs in breast milk and their toxicity, continuous studies on infant exposure, fetal growth, and child neurodevelopment are requested.

Organophosphate esters and their diester metabolites in infant formulas and baby supplementary foods collected in Beijing, China: Occurrence and the implications for infant exposure

Organophosphate esters (OPEs) have been extensively used as flame retardants and/or plasticizers and they found to be ubiquitous in various environmental matrices along with the gradual phase-out of brominated flame retardants (BFRs). Moreover, their main metabolites, organophosphate di-esters (di-OPEs), were also frequently detected. However, few studies focused on the occurrence of OPEs and di-OPEs in foods. In this study, fourteen OPEs and five di-OPEs were measured in infant formula and baby supplementary food (BSF) collected in Beijing, China. Most OPEs and di-OPEs presented high detection frequencies, which indicated their ubiquity in baby foods. The concentrations of ∑₁₄OPEs in the 75 infant formula samples ranged from 0.79 to 159 ng/g, with a median of 23.2 ng/g, and in which triphenyl phosphate (TPhP) was the most abundant compound. The concentrations of ∑₁₄OPEs in the 32 BSF samples were 4.42-115 ng/g (median: 19.5 ng/g), and tri(3-chloropropyl) phosphate (TCIPP) was predominant. Moreover, no significant difference was observed between OPE levels in infant formula and BSF. The median concentrations of Σ₅di-OPEs in infant formula and BSF were 3.39 and 5.43 ng/g, respectively. However, no significantly correlation was observed between concentrations of di-OPEs and their parent compounds, which indicated they have different sources. The median estimated dietary intakes (EDIs) of the ∑₁₄OPEs were from 165 to 383 ng/kg bodyweight (bw)/day for infants via infant formula feeding, and were from 429 to 470 ng/kg bw/day via BSF feeding. A comparison to corresponding reference dose (RfD) suggested that dietary intakes of OPEs to Beijing infants via formula/BSF consumption were still unable to cause significant health concerns. However, EDIs of OPEs for infants were found to be significantly higher than that for Chinese adults, and dietary intake might be the predominant OPE intake pathway for infants. To our knowledge, this is the first study to investigate OPEs and their metabolites in baby foods.

Polychlorinated dioxins and dibenzofurans (PCDD/F), polybrominated dioxins and dibenzofurans (PBDD/F), polychlorinated biphenyls (PCB), polybrominated diphenyl ethers (PBDE), and per- and polyfluoroalkyl substances (PFAS) in German breast milk samples (LUPE 8)

Most organic pollutants (POP) are persistent in the environment, accumulate in fatty tissues, and so a transfer through the food chain is probably, thereby causing various health effects. We quantified PCDD/F, PBDD/F, PCB, PBDE, perfluorinated substances, and ADONA in breast milk samples collected in two German federal states and breast milk and blood samples from subjects additionally exposed to PFOA. The median (95th percentile) concentrations were 2.43 (6.58) pgWHO₂₀₀₅TEQ/g l.w. for PCDD/F, 2.45 (4.82) pgWHO₂₀₀₅TEQ/g l.w. for dioxin-like PCB (dl-PCB), and 0.62 (2.69) pgWHO₂₀₀₅TEQ/g l.w. for PBDD/F. The relative contributions of the median values of PCDD/F, dl-PCB, and PBDD/F to the total-TEQ were approximately 41%, 42%, and 11%, respectively. Nondioxin-like PCB (ndl-PCB) concentrations were clearly dominated by the higher chlorinated PCB congeners, with medians of 23.2 ng/g l.w. for PCB 153, 13.9 ng/g l.w. for PCB 138, and 13.0 ng/g l.w. for PCB 180. The sum of the 3 congeners (PCB 138, 153, and 180) were multiplied with 1.64 (total PCB) and showed a median of 82.16 ng/g l.w. and a 95th percentile of 173.3 ng/g l.w. Only PFOA and PFOS could be quantified in 29% and 17% of in total 180 samples with 95th percentiles of 53 ng/l and 33 ng/l, respectively. Milk samples (n = 13) from subjects living on PFOA contaminated sites showed higher levels between 33 and 854 ng/l PFOA (mean: 199 ng/l), whilst PFOS could be quantified only in three samples. The sum of 17 PBDE congeners showed medians (95th percentile) of 1737 pg/g l.w. (22,806 pg/g l.w.), with the highest medians of 422 pg/g l.w. for BDE 209 and 378 pg/g l.w. for BDE 153. Overall, our study confirms the declining contamination level in breast milk during the last decade, but points out the need to further reduce the environmental contamination with persistent substances and subsequently the exposure in childhood.

Critical review of analytical methods for the determination of flame retardants in human matrices

Human biomonitoring is a powerful approach in assessing exposure to environmental pollutants. Flame retardants (FRs) are of particular concern due to their wide distribution in the environment and adverse health effects. This article reviews studies published in 2009-2020 on the chemical analysis of FRs in a variety of human samples and discusses the characteristics of the analytical methods applied to different FR biomarkers of exposure, including polybrominated diphenyl ethers (PBDEs), hexabromocyclododecane (HBCD), novel halogenated flame retardants (NHFRs), bromophenols, incl. tetrabromobisphenol A (TBBPA), and organophosphorous flame retardants (PFRs). Among the extraction techniques, liquid-liquid extraction (LLE) and solid phase extraction (SPE) were used most frequently due to the good efficiencies in the isolation of the majority of the FR biomarkers, but with challenges for highly lipophilic FRs. Gas chromatography-mass spectrometry (GC-MS) is mainly applied in the instrumental analysis of PBDEs and most NHFRs, with recent inclusions of GC-MS/MS and high resolution MS techniques. Liquid chromatography-MS/MS is mainly applied to HBCD, bromophenols, incl. TBBPA, and PFRs (including metabolites), however, GC-based analysis following derivatization has also been used for phenolic compounds and PFR metabolites. Developments are noticed towards more universal analytical methods, which enable widening method scopes in the human biomonitoring of FRs. Challenges exist with regard to sensitivity required for the low concentrations of FRs in the general population and limited sample material for some human matrices. A strong focus on quality assurance/quality control (QA/QC) measures is required in the analysis of FR biomarkers in human samples, related to their variety of physical-chemical properties, low levels in most human samples and the risk of contamination.

Legacy brominated flame retardants in human milk from the general population in Beijing, China: Biomonitoring, temporal trends from 2011 to 2018, and nursing infant's exposure assessment

Three kinds of legacy brominated flame retardants (BFRs), including eight polybrominated diphenyl ether (PBDE) congeners, tetrabromobisphenol A (TBBPA), and three hexabromocyclododecane (HBCDD) isomers, were analyzed in 105 human milk samples collected in 2018 from Beijing, China. The tested BFRs all showed high detection frequencies, and HBCDD was the most abundant BFR, with a median level of 7.64 × 10³ pg/g lipid, followed by BDE-153 (389 pg/g lipid), BDE-209 (283 pg/g lipid), and TBBPA (271 pg/g lipid). By comparing the results of the present study with those of our previous Beijing human milk surveys conducted in 2014 and 2011, the contamination of TBBPA and HBCDD increased steadily from 2011 to 2018, whereas that of PBDEs decreased sharply during this period. Our results suggested that the production and consumption of BFRs in China have shifted from PBDEs to other FRs. Education level and the consumption of animal-derived foods such as eggs and meat were identified as major influencing factors for some BFRs. For nursing infants, the median levels of lower bound BFR daily intake via human milk ingestion ranged from 4.62 × 10^-2 ng/kg bw/day for BDE-154 to 30.6 ng/kg bw/day for HBCDD. The daily intake of most BFRs by breastfeeding is unlikely to pose significant health risks for Beijing nursing infants. However, the minimum margin of exposure (MOE) of HBCDD was below its threshold value, which indicated that its daily intake might raise health concerns for some breastfed infants.

Occurrence and Dietary Intake of Organophosphate Esters via Animal-Origin Food Consumption in China: Results of a Chinese Total Diet Study

Although diet is regarded as a major exposure source of organophosphate esters (OPEs), the dietary survey of OPEs in China has been limited. Based on the sixth Chinese Total Diet Study (TDS) conducted during 2016-2019 in 24 of 34 provinces in China, 14 OPEs were detected in 96 food composites from four animal-origin food categories. Twelve OPEs were detected in more than 80% of the samples and 2-ethylhexyl diphenyl phosphate (EHDPP) presented the highest median concentration (1.63 ng/g wet weight (ww)). The most contaminated food composite was meat, with a median ∑₁₄OPEs of 13.6 ng/g ww, followed by aquatic food (11.5 ng/g ww), egg (7.63 ng/g ww), and milk (3.51 ng/g ww). The contribution of the meat group was close to or even greater than 50% in the estimated dietary intake (EDI) of OPEs. The average (range) EDI of the ∑₁₄OPEs via animal food consumption for a Chinese "standard man" was 34.4 (6.18-73.3) ng/kg bodyweight (bw)/day. The geographical distribution showed higher EDI in southern coastal provinces compared to the northern inland provinces. Nevertheless, the highest EDI of ∑₁₄OPEs from animal food was still more than 10 times lower than the reference dose. This is the first national survey of OPEs in foods from China.

A review on the analytical procedures of halogenated flame retardants by gas chromatography coupled with single quadrupole mass spectrometry and their levels in human samples

Halogenated flame retardants (HFRs) market is continuously evolving and have moved from the extensive use of polybrominated diphenyl ether (PBDE) to more recent introduced mixtures such as Firemaster 550, Firemaster 680, DP-25, DP-35, and DP-515. These substitutes are mainly composed of non-PBDEs HFRs such as 2-ethyl-hexyl tetrabromobenzoate (TBB), bis(2-ethylhexyl) tetrabromophthalate (TBPH), 1,2-bis-(2,4,6-tribromophenoxy) ethane (BTBPE) and decabromodiphenyl ethane (DBDPE). Other HFRs commonly being monitored include Dechlorane Plus (DP), Dechlorane 602 (Dec602), Dechlorane 603 (Dec603), Dechlorane 604 (Dec604), 5,6-dibromo-1,10, 11, 12,13,13-hexachloro- 11-tricyclo[8.2.1.02,9]tridecane (HCDBCO) and 4,5,6,7-tetrabromo-1,1,3-trimethyl-3-(2,3,4,5-tetrabromophenyl)-2,3-dihydro-1H-indene (OBTMPI). This review aims at highlighting the advances in the past decade (2010-2020) on both the analytical procedures of HFRs in human bio-specimens using gas chromatography coupled with single quadrupole mass spectrometry and synthesizing the information on the levels of these HFRs in human samples. Human specimen included in this review are blood, milk, stool/meconium, hair and nail. The review summarizes the analytical methods, including extraction and clean-up techniques, used for measuring HFRs in biological samples, which are largely adopted from those for analysing PBDEs. In addition, new challenges in the analysis to include both PBDEs and a wide range of other HFRs are also discussed in this review. Review of the levels of HFRs in human samples shows that PBDEs are still the most predominant HFRs in many cases, followed by DP. However, emerging HFRs are also being detected in human despite of the fact that both their detection frequencies and levels are lower than PBDEs and DP. It is clearly demonstrated in this review that people working in the industry or living close to the industrial areas have higher HFR levels in their bodies.

Polybrominated diphenyl ethers (PBDEs) in raw milk from different animal species and in infant formula. Occurrence and risk assessment

Polybrominated diphenyl ethers (PBDEs) are widespread, persistent in the environment, and classified as global pollutants. Their presence has been confirmed in various types of food which adversely affect human health when consumed in sufficient amounts. Although milk has advantageous nutritional qualities and there are health benefits associated with its consumption, it could also contain toxic PBDEs. The aim of the study was the determination of the concentrations of ten congeners (BDE -28, -47, -49, -99, -100, -138, -153, -154, -183, and 209) in cow's, sheep's, and goat's milk obtained from Polish farms and their determination in infant formula. A total of 103 samples of raw milk and infant formula were tested using an accredited high-resolution gas chromatography-high-resolution mass spectrometry method. PBDEs were detected in all analyzed samples, the highest concentration being found in sheep's milk (11.9 ng g^-1 fat), and cow's milk containing the least contamination. BDE-209 makes the predominant contribution to the sum of the ten congeners, constituting at least 38%. The profiles of PBDEs were dependent on the milk type and the differences between its varieties are discussed. The highest median concentration of the sum of ten PBDEs (0.473 ng g^-1 fat) was determined in infant formula, which was identified as an important source of infants' exposure (5.48 ng kg^-1 b.w. day^-1 calculated based on P95 concentration). Milk is a source of PBDE in the diet; however, considered in isolation its consumption does not pose a risk to either adults' or children's health.

Occurrence, bioaccumulation, fate, and risk assessment of novel brominated flame retardants (NBFRs) in aquatic environments - A critical review

Novel brominated flame retardants (NBFRs), which have been developed as replacements for legacy flame retardants such as polybrominated diphenyl ethers (PBDEs), are a class of alternative flame retardants with emerging and widespread applications. The ubiquitous occurrence of NBFRs in the aquatic environments and the potential adverse effects on aquatic organisms have initiated intense global concerns. The present article, therefore, identifies and analyzes the current state of knowledge on the occurrence, bioaccumulation, fates, and environmental and health risks of NBFRs in aquatic environments. The key findings from this review are that (1) the distribution of NBFRs are source-dependent in the global aquatic environments, and several NBFRs have been reported at higher concentrations than that of the legacy flame retardants; (2) high bioaccumulative properties have been found for all of the discussed NBFRs due to their strong hydrophobic characteristics and weak metabolic rates; (3) the limited information available suggests that NBFRs are resistant to biotic and abiotic degradation processes and that sorption to sludge and sediments are the main fate of NBFRs in the aquatic environments; (4) the results of ecological risk assessments have indicated the potential risks of NBFRs and have suggested that source areas are the most vulnerable environmental compartments. Knowledge gaps and perspectives for future research regarding the monitoring, toxicokinetics, transformation processes, and development of ecological risk assessments of NBFRs in aquatic environments are proposed.

Polybrominated diphenyl ethers in the environmental systems: a review

PBDEs are human-influenced chemicals utilized massively as flame retardants. They are environmentally persistent, not easily degraded, bioaccumulate in the biological tissue of organisms, and bio-magnify across the food web. They can travel over a long distance, with air and water being their possible transport media. They can be transferred to non-target organisms by inhalation, oral ingestion, breastfeeding, or dermal contact. These pollutants adsorb easily to solid matrices due to their lipophilicity and hydrophobicity; thus, sediments from rivers, lakes, estuaries, and ocean are becoming their major reservoirs aquatic environments. They have low acute toxicity, but the effects of interfering with the thyroid hormone metabolism in the endocrine system are long term. Many congeners of PBDEs are considered to pose a danger to humans and the aquatic environment. They have shown the possibility of causing many undesirable effects, together with neurologic, immunological, and reproductive disruptions and possible carcinogenicity in humans. PBDEs have been detected in small amounts in biological samples, including hair, human semen, blood, urine, and breastmilk, and environmental samples such as sediment, soil, sewage sludge, air, biota, fish, mussels, surface water, and wastewater. The congeners prevailing in environmental samples, with soil being the essential matrix, are BDE 47, 99, and 100. BDE 28, 47, 99, 100, 153, 154, and 183 are more frequently detected in human tissues, whereas in sediment and soil, BDE 100 and 183 predominate. Generally, BDE 153 and 154 appear very often across different matrices. However, BDE 209 seems not frequently determined, owing to its tendency to quickly breakdown into smaller congeners. This paper carried out an overview of PBDEs in the environmental, human, and biota niches with their characteristics, physicochemical properties, and fate in the environment, human exposure, and health effects.

Organophosphorus flame retardants in breast milk from Beijing, China: Occurrence, nursing infant's exposure and risk assessment

Organophosphorus flame retardants (OPFRs) are widely used chemicals, whereas data on OPFRs in human being is limited. In this study, thirteen OPFRs were measured in 105 breast milk samples collected from Beijing mothers in 2018. The ∑₁₃OPFRs ranged from <LOD to 106 ng mL^-1 (<LOD-6700 ng g^-1 lipid weight (lw)), with a median value 10.6 ng mL^-1 (157 ng g^-1 lw). The most abundant compound was tris(2-ethylhexyl) phosphate (TEHP), followed by triphenyl phosphate (TPhP) and 2-ethylhexyl diphenyl phosphate (EHDPP). The detecting frequencies and contamination levels of OPFRs in our study were higher than those reported in other studies, which indicated that China is one of the most affected regions by OPFRs. In addition, OPFR levels in our study were found to be higher than levels of brominated flame retardants (BFRs) in human milk from China. Based on regression analyses, mothers' personal characters, including age, pregnancy, residing/working location, and educational level were found to be impact factors of some OPFRs in breast milk. Estimated daily intakes (EDI) of the OPFRs for nursing infants via human milk ingest were calculated, and the mean EDIs of the 13 OPFRs ranged from 2.62 to 1640 ng kg^-1 bw d^-1. Since the mean and max EDIs of most OPFRs were lower than corresponding reference doses (RfDs), the daily OPFR intake for most nursing infants would not cause significant health concerns. However, the max EDIs of two OPFRs, TPhP and EHDPP, with values of 1.09 × 10⁴ and 2190 ng kg^-1 bw d^-1, respectively, were higher than their corresponding RfDs. To our knowledge, this is the first report on the occurrence of OPFRs in human milk from China.

Assessment of polybrominated diphenyl ethers and emerging brominated flame retardants in Pheretima (a Traditional Chinese Medicine): Occurrence, residue profiles, and potential health risks

China produces and consumes large quantities of brominated flame retardants (BFRs) as well as several other unregulated electronic waste recycling activities, causing high BFR concentrations in the natural environment. Thus, Traditional Chinese Medicines (TCMs) may be contaminated by legacy BFRs (e.g. polybrominated diphenyl ethers (PBDEs)) and emerging BFRs (eBFRs, such as decabromodiphenyl ethane (DBDPE)) during growth, processing, packaging, and transportation. Pheretima, which is a typical animal drug recorded in Chinese Pharmacopoeia, was used as an example to evaluate human exposure to BFRs through TCM intake. This study is the first to determine 25 PBDEs and 5 eBFRs in Pheretima and estimate the daily BFR intake via Pheretima-containing TCMs. Twenty-seven Shanghai Pheretima and fifty-one Guang Pheretima samples were collected between March and June 2019 in southeast China. High BFR detection frequencies were found in Pheretima, of which BDE-209 and DBDPE were the most predominant analytes. The total PBDE contents ranged from 73 pg/g to 8,725 pg/g, while that of the eBFRs varied between 115 pg/g and 2,824 pg/g. The profiles and abundances were found to be species- and origin-dependent. However, the traditional processing of Pheretima may reduce BFR residues. Based on the usual clinical doses of Pheretima and the available chronic oral reference doses of BDE-47, 99, 153, and 209, the mean (95th percentile) of the total hazard quotient was estimated to be 9.1 × 10^-5 (2.7 × 10^-4). Therefore, there is little risk related to BFR exposure for patients taking formulated Pheretima-containing TCMs. However, it is necessary to establish routine monitoring programs for the co-existence of pollutants in TCMs to perform a systematic and comprehensive risk assessment.

Semi-Volatile Organic Compounds in Car Dust: A Pilot Study in Jeddah, Saudi Arabia

People may spend a significant amount of their daily time in cars and thus be exposed to chemicals present in car dust. Various chemicals are emitted from during car use, contaminating the car dust. In this study, we compiled published and unpublished data on the occurrence of phthalates, flame retardants (FRs), polycyclic aromatic hydrocarbons (PAHs), and polychlorinated biphenyls (PCBs) in Saudi car dust. Phthalates, a class of chemical commonly used as plasticizers in different car parts, were the major pollutants found in car dust, with a median value of ∑phthalates 1,279,000 ng/g. Among other chemicals, organophosphate flame retardants (OPFRs) were found to be between 1500-90,500 ng/g, which indicates their use as alternative FRs in the car industry. The daily exposure to Saudi drivers (regular and taxi drivers) was below the respective reference dose (RfD) values of the individual chemicals. However, the estimated incremental lifetime cancer risk (ILCR) values due to chronic exposure to these chemicals was >1 × 10^-5 for taxi drivers for phthalates and PAHs, indicating that the long-term exposure to these chemicals is a cause of concern for drivers who spend considerable time in cars. The study has some limitations, due to the small number of samples, lack of updated RfD values, and missing cancer slope factors for many studied chemicals. Despite these limitations, this study indicates the possible range of exposure to drivers from chemicals in car dust and warrants further extensive studies to confirm these patterns.

The brominated flame retardants TBECH and DPTE alter prostate growth, histology and gene expression patterns in the mouse

The brominated flame retardants (BFRs), 1,2-dibromo-4-(1,2 dibromoethyl)cyclohexane (TBECH) and 2,3-dibromopropyl-2,4,6-tribromophenyl ether (DPTE) bind to the androgen receptor (AR). in vitro bioassays have shown that TBECH is a potent androgen agonist while DPTE is a potent AR antagonist. Both TBECH and DPTE alter gene expression associated with AR regulation. However, it remains to be determined if TBECH and DPTE can affect the prostate. For this reason, we exposed CD1 mice to a 1:1 mixture of TBECH diastereomers α and β, a 1:1 mixture of γ and δ, and to DPTE, and tested their effects on prostate growth, histology and gene expression profiles. Castrated mice were used to study the androgenic effects of TBECHαβ and TBECHγδ while the antagonistic effects of DPTE were studied in non-castrated mice. We observed that testosterone and TBECHγδ increased body and prostate weights while TBECHαβ affected neither of them; and that DPTE had no effect on body weight but reduced prostate weight drastically. Histomorphometric analysis of the prostate revealed epithelial and glandular alterations in the TBECHγδ group comparable to those in testosterone group while alterations in the TBECHαβ group were less pronounced. DPTE displayed androgen antagonist activity reminiscent of castration. The transcription profile of the prostate was altered by castration and exposure to testosterone and to TBECHγδ reversed several of these changes. Testosterone and TBECHγδ also regulated the expression of several androgen responsive genes implicated in prostate growth and cancer. While DPTE resulted in a drastic reduction in prostate weight, it only affected a small number of genes. The results indicate that TBECHγδ and DPTE are of high human health concern as they may contribute to changes in prostate growth, histology and function.

Global distribution and trends of polybrominated diphenyl ethers in human blood and breast milk: A quantitative meta-analysis of studies published in the period 2000-2019

Polybrominated diphenyl ethers (PBDEs) are a class of flame-retardants that are found throughout the human body. However, global trends and diversity of the concentrations in human body and the potential risks remain largely unresolved. Based on published data during 2000-2019, we conducted a systematic meta-analysis to understand the burden and risks of PBDEs in humans and their spatiotemporal variations. The report provides a global picture of PBDE concentrations in human blood and breast milk. We found the levels of body PBDE burden in the North American population were higher than those from Asia and Europe. However, high concentrations of blood PBDEs in occupational population from Asia were observed, largely because of poorly controlled e-waste recycling operations. Penta- and deca-BDE were the main contributors in North America and Asia, respectively, reflecting the difference in the production and use of these chemicals. On a global scale, no substantial decreases in the concentrations of PBDEs in the blood and breast milk were observed, although most of the chemicals have been phased out. The results suggested that humans will be exposed to PBDEs with relatively high concentrations in a certain period because of the legacy in products and the environmental media. And the potential health risks necessitate careful study in the future. Our results also remind that the uses of degradation-resistant chemicals should be attached great importance to their safety.

Levels and profiles of persistent organic pollutants in breast milk in China and their potential health risks to breastfed infants: A review

Although some persistent organic pollutants (POPs) were prohibited or limited in use several decades ago, they are still frequently detected in the human body. The purpose of this study was to understand the levels and profiles of POPs in breast milk in China and assess their potential health risks among breastfed infants under six months of age. A literature review focused on China was performed for studies published from 2001 to 2020. The POP levels in breast milk along with other important variables were extracted, and then the average individual POP levels in breast milk were estimated. This review summarises the distribution of traditional and new POPs, including polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), legacy brominated flame retardants (BFRs), perfluorinated compounds (PFCs), and chlorinated paraffins (CPs) and reported notably high levels of short-chain chlorinated paraffins and 1,1-dichloro-2,2-bis (p-chlorophenyl) ethylene (p,p'-DDE) in breast milk. Although the levels of traditional POPs generally declined over time, especially p,p'-DDE and beta-hexachlorocyclohexane (β-HCH), women living in coastal areas, urban areas, and southern China still have a high body burden of certain POPs. In the present study, the estimated daily intake (EDI) of POPs through breastfeeding was used to evaluate the health risk for infants by comparing with acceptable levels. The findings suggested that infants born in coastal areas most likely suffered potential health risk from exposure to DDT, and the health risk of hexachlorobenzene (HCB) in infants in most nationwide regions remains a concern. More importantly, the EDI of PCBs for infants exceeds the safe limit on a national scale. Continuous surveillance of PCBs in breast milk is critical to evaluate the potential health effects on humans.

Occurrence and mass balance of emerging brominated flame retardants in a municipal wastewater treatment plant

As a class of alternative flame retardants, "novel" brominated flame retardants (NBFRs) have been widely used in clothing, textiles, electronics, building materials, and plastics and are frequently found in environmental samples. Although the use and discharge of NBFRs are increasing all over the world, little information is available about their fates and removal in wastewater treatment plants (WWTPs). This study investigated the occurrence and behavior of 2,4,6-tribromophenyl allyl ether (ATE), 2,3-dibromopropyl tribromophenyl ether (DPTE), tetrabromo-o-chlorotoluene (TBCT), pentabromobenzyl acrylate (PBBA), 1,2-bis(2,4,6-tribromophenoxy) ethane (BTBPE), bis(2-ethylhexyl)-3,4,5,6-tetrabromo-phthalate (TBPH), and decabromodiphenyl ethane (DBDPE) in a municipal WWTP in Beijing, China. Four of the NBFRs (ATE, BTBPE, TBPH, and DBDPE) were detected in all wastewater and biosolid samples. The dominant compound in both wastewater and biosolid samples was DBDPE, with concentrations in the ranges of 6.4-18 ng/L and 83-288 ng/g dry weight (dw), respectively. A mass flow analysis indicated that the overall removal efficiencies were 31±18% for ATE, 97±1.5% for DPTE, 79±11% for BTBPE, 87±5.3% for TBPH, and 93±3.3% for DBDPE, but the removal efficiency in aqueous phase only ranged from -43 (ATE) to 57% (DBDPE). The low and negative removal efficiencies of ATE were possibly due to the transformation of DPTE during the anaerobic treatment processes. Under the aerobic conditions, BTBPE, TBPH and DBDPE underwent a very slow biodegradation. A total of 68-91% of the initial mass loadings of ATE, BTBPE, TBPH and DBDPE were found in the biosolid samples, suggesting that the four NBFRs were removed mainly via sorption in the WWTP.The biosolid was a huge reservoir of target NBFRs, and effective removal of NBFRs during treatment in the WWTP is critical.

Transfer of dechlorane plus between human breast milk and adipose tissue and comparison with legacy lipophilic compounds

In this study, levels of dechlorane plus (DP) in breast milk and matched adipose tissue samples were measured from 54 women living in Wenling, China. Polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) were measured simultaneously for comparison. The levels of ∑DPs/∑PBDEs varied from less than one to several dozens of ng g^-1 lipid weight (lw) in matrices and the levels of ∑PCBs varied between several to hundreds of ng g^-1 lw. In the same matrix, ∑DPs and ∑PCBs/∑PBDEs showed a significant relationship (p < 0.05), indicating that they shared common sources. Accordingly, there was a strong association of lipid-adjusted concentrations of individual compounds (BDE-209 excluded) between matrices (p < 0.001), suggesting that breast milk could be a proxy for adipose tissue in human bioburden monitoring of these compounds. The predicted lipid-adjusted milk/adipose ratios varied from 0.62 to 1.5 but showed significant differences (p<0.001) between compounds, suggesting a compound-specific transfer between milk lipids and adipose tissue lipids. Specifically, the milk/adipose ratios for syn-DP and anti-DP (-1.40 and 1.3, respectively) were significantly higher than those of CB congeners and hexa/hepta-BDE congeners (p < 0.05). In addition, unlike PCBs/PBDEs (excluding BDE-209), DP's hydrophobicity might not be responsible for its preferable distribution in milk lipids. Instead, the interaction with nonlipid factors played a key role. The fraction of anti-DP between the two kinds of matrices was not significantly different, suggesting that the biochemical transfer processes may not be efficient enough to distinguish DP isomers. Nevertheless, the congener patterns of PCBs/PBDEs gave a clue about the compound-specific transfer between milk and adipose tissue. To our knowledge, this is the first to report the relationships of DP between adipose tissue and breast milk. These results could provide useful and in-depth information on biomonitoring of DP and facilitate the understanding of the accumulation and excretion potentials of DP and its distribution-related mechanism in humans.

Polybrominated diphenyl ethers and decabromodiphenyl ethane in paired hair/serum and nail/serum from corresponding chemical manufacturing workers and their correlations to thyroid hormones, liver and kidney injury markers

We detected the polybrominated diphenyl ethers (PBDEs) or decabromodiphenyl ethane (DBDPE) in paired hair-serum and nail-serum samples collected from the corresponding chemical manufacturing workers. The levels of decabrominated diphenyl ether (BDE-209) or DBDPE in the serum, hair and nail samples were all significantly higher than those reported in other studies, and the "work place" (pretreatment or posttreatment workshop) was the primary influencing factor that affected the levels of specific BFRs in vivo. For BDE-209 workers, the BDE-209 in both the hair and nail samples were significantly and positively related to the BDE-209 in the serum, indicating that both hair and nails can be used as noninvasive biomatrices to reflect internal exposure to BDE-209. In DBDPE workers, hair rather than nails was more suitable for use as a noninvasive biomatrix to infer the DBDPE exposure level. A series of serum biomarkers reflecting thyroid hormones and liver and kidney injuries were tested to calculate the correlations between hair or nail BFR levels and the levels of the biomatrices. The BDE-209 in the hair samples was significantly and positively correlated with the total protein (TP), and the nail BDE-209 level was significantly and positively related to the total bilirubin (TBIL), indirect bilirubin (IDBIL) and uric acid (UA). The DBDPE in hair was significantly and positively correlated with the thyroid hormones free triiodothyronine (fT3) and total triiodothyronine (tT3) and kidney injury markers, including blood urea nitrogen (BUN), creatinine (CRE) and cystatin C (Cys-C). In addition, the nail DBDPE levels were significantly and positively correlated with the albumin/globulin (A/G), BUN, CRE and Cys-C but negatively correlated with the TP and globulin (GLO). Our findings provide preliminary evidence that hair and nails can be used as noninvasive biomatrices for assessing internal BFR exposure and health damage in occupational workers.

Exposure pathways, levels and toxicity of polybrominated diphenyl ethers in humans: A review

Polybrominated diphenyl ethers (PBDEs) are extensively used as brominated flame retardants (BFRs) in different types of materials, which have been listed as Persistent Organic Pollutants (POPs) by the Stockholm Convention in 2009 and 2017. Due to their ubiquities in the environment and toxicities, PBDEs have posed great threat to both human health and ecosystems. The aim of this review is to offer a comprehensive understanding of the exposure pathways, levels and trends and associated health risks of PBDEs in human body in a global scale. We systematically reviewed and described the scientific data of PBDE researches worldwide from 2010 to March 2020, focusing on the following three areas: (1) sources and human external exposure pathways of PBDEs; (2) PBDE levels and trends in humans; (3) human data of PBDEs toxicity. Dietary intake and dust ingestion are dominant human exposure pathways. PBDEs were widely detected in human samples, especially in human serum and human milk. Data showed that PBDEs are generally declining in human samples worldwide as a result of their phasing out. Due to the common use of PBDEs, their levels in humans from the USA were generally higher than that in other countries. High concentrations of PBDEs have been detected in humans from PBDE production regions and e-waste recycling sites. BDE-47, -153 and -99 were proved to be the primary congeners in humans. Human toxicity data demonstrated that PBDEs have extensively endocrine disruption effects, developmental effects, and carcinogenic effects among different populations.

Indoor polybrominated diphenyl ethers in urban China: An exposure and risk assessment based on settled dust from selected urban regions

In this study, measurements of seven typical polybrominated diphenyl ethers (PBDEs) in indoor settled dust were summarized in selected urban regions of China. BDE-209 was the most dominant congener in settled dust (1.4-101 μg/g), with a mean contribution of 95%. Indoor exposures to PBDEs were estimated via inhalation, dust ingestion, and dermal absorption. The average daily intake of ΣPBDE was 4.9 to 19.1 ng/day/kg for all the population groups, with >80% of the total exposures from dust ingestion. Exposures in commuting environments (contributing 60%-80% of the total exposures) were higher than those in other microenvironments. The means of hazard indexes ranged from 1.66 × 10^-3 to 5.26 × 10^-3, which were mainly as a result of exposure to BDE-209, BDE-47, and BDE-99. The average lifetime cancer risks were from 0.03 × 10^-9 to 2.37 × 10^-9, which indicated the acceptable health risks resulting from indoor PBDE exposure for the Chinese population. The present study could provide valuable information that could be helpful for decision-makers, analysts and researchers to develop, implement and evaluate the effectiveness of interventions for the reduction of exposures to semi-volatile organic compounds (SVOCs) for large population groups in China.

Tetrabromobisphenol A and hexabromocyclododecane isomers in breast milk from the general population in Beijing, China: Contamination levels, temporal trends, nursing infant's daily intake, and risk assessment

Two currently used brominated flame retardants (BFRs), α, β, γ-hexabromocyclododecane (HBCDD) and tetrabromobisphenol A (TBBPA), were measured in 111 breast milk samples from 37 Beijing mothers. Each mother provided one milk sample per month for 3 months. HBCDD was detected in almost all samples, and the median level reached 5.67 ng g^-1 lipid weight (lw). α- HBCDD was the most abundant isomer (median: 4.23 ng g^-1 lw), followed by γ- and β-HBCDD. For TBBPA, a relatively lower detecting frequency (64%) and contamination level (median: 1.57 ng g^-1 lw) were obtained. A comparison to our previous study revealed that the occurrence of TBBPA and HBCDD in Beijing human milk significantly rose from 2011 to 2014, whereas another commonly used class of BFRs, polybrominated diphenyl ethers (PBDEs), showed significantly decreased during this period. However, a comparison among currently used BFRs showed that levels of some BFRs, such as HBCDD, surpassed those of PBDEs, which indicated that PBDEs were no longer the primarily used BFR in China. However, no significant temporal trends for BFR levels were observed over the 3 months of lactation. Daily intakes of TBBPA and HBCDD were calculated for nursing infants and the median TBBPA and HBCDD intakes via breastfeeding were 6.62 and 26.4 ng kg^-1 bw day^-1, respectively. These values were several times higher than those for adults via food consumption. However, risk assessment using the margin of exposure approach indicated that intakes of TBBPA and HBCDD via breastfeeding can scarcely cause significant health risks to infants.

Levels and distribution of polybrominated diphenyl ethers in humans and environmental compartments: a comprehensive review of the last five years of research

Polybrominated diphenyl ethers (PBDEs) are a class of brominated flame retardants (BFRs), present in the environment, animals, and humans. Their levels, distribution, and human exposure have been studied extensively, and over the last decade, various legal measures have been taken to prohibit or minimize their production and use due to the increasing amount of evidence of their harmful effects on human and animal health.Our aim here was to make a comprehensive and up-to-date review of the levels and distribution of PBDEs in the aquatic environment, air, and soil, in indoor dust, and in humans. To fulfill this, we searched through Web of Science for literature data reported in the last five years (2015-2019) on levels of at least six key PBDE congeners in abovementioned matrices. According to our summarized data, significant PBDE mass concentrations/fractions are still being detected in various sample types across the world, which implies that PBDE contamination is an ongoing problem. Secondary sources of PBDEs like contaminated soils and landfills, especially those with electronic and electrical waste (e-waste), represent a particular risk to the future and therefore require a special attention of scientists.