Serum polybrominated diphenyl ether concentrations and thyroid function in young children

Prenatal exposure to persistent and non-persistent chemical mixtures and associations with adverse birth outcomes in the Atlanta African American Maternal-Child Cohort

BACKGROUND

African Americans (AAs) experience higher rates of preterm birth and fetal growth restriction relative to other pregnant populations. Differential in utero exposure to environmental chemicals may partially explain these health disparities, as AAs are disproportionately exposed to environmental hazards.

OBJECTIVE

We examined the individual and mixture effects of non-persistent chemicals and persistent organic pollutants (POPs) on gestational age at birth and birthweight for gestational age z-scores within a prospective cohort of pregnant AAs.

METHODS

First-trimester serum and urine samples obtained from participants within the Atlanta African American Maternal-Child cohort were analyzed for 43 environmental chemicals, including per-and polyfluoroalkyl substances (PFAS), polybrominated diphenyl ethers (PBDEs), organochlorine pesticides, pyrethroid insecticides, phthalates, bisphenol A, nicotine, and the primary metabolite of delta-9-tetrahydrocannabinol. Linear regression was used to estimate individual associations between chemicals and gestational age and birthweight z-scores (N ranging from 107 to 523). Mixture associations were estimated using quantile g-computation, principal component (PC) analyses, and hierarchical Bayesian kernel machine regression among complete cases (N = 86).

RESULTS

Using quantile g-computation, increasing all chemical exposures by one quantile was modestly associated with a reduction in gestational age (mean change per quartile increase = -0.47, 95% CI = -1.56, 0.61) and birthweight z-scores (mean change per quartile increase = -0.49, 95% CI = -1.14, 0.15). All PCs were associated with a reduction in birthweight z-scores; associations were greatest in magnitude for the two PCs reflecting exposure to combined tobacco, insecticides, PBDEs, and phthalates. In single pollutant models, we observed inconsistent and largely non-significant associations.

SIGNIFANCE

We conducted multiple targeted exposure assessment methods to quantify levels of environmental chemicals and leveraged mixture methods to quantify their joint effects on gestational age and birthweight z-scores. Our findings suggest that prenatal exposure to multiple classes of persistent and non-persistent chemicals is associated with reduced gestational age and birthweight z-scores in AAs.

IMPACT

African Americans (AAs) experience higher rates of preterm birth and fetal growth restriction relative to other pregnant populations. Differential in utero exposure to environmental chemicals may partially explain these health disparities, as AAs are disproportionately exposed to environmental hazards. In the present study, we analyzed serum and urine samples for levels of 43 environmental chemicals. We used quantile g-computation, principal component analysis, and BKMR to assess associations between chemical exposure mixtures and adverse birth outcomes. Our findings suggest that prenatal exposure to multiple classes of chemicals is associated with reduced birthweight z-scores, a proxy for fetal growth, in AAs.

A Review of the Association between Exposure to Flame Retardants and Thyroid Function

Flame retardants have been shown to cause widespread physiological effects, in particular on endocrine organs such as the thyroid. This review aims to provide an overview of the literature on the association between flame retardants and thyroid function within humans. A search in the National Library of Medicine and National Institutes of Health PubMed database through January 2024 yielded 61 studies that met the inclusion criteria. The most frequently analyzed flame retardants across all thyroid hormones were polybrominated diphenyl ethers (PBDEs), in particular BDE-47 and BDE-99. Ten studies demonstrated exclusively positive associations between flame retardants and thyroid stimulating hormone (TSH). Six studies demonstrated exclusively negative associations between flame retardants and TSH. Twelve studies demonstrated exclusively positive associations for total triiodothyronine (tT3) and total thyroxine (tT4). Five and eight studies demonstrated exclusively negative associations between flame retardants and these same thyroid hormones, respectively. The effect of flame retardants on thyroid hormones is heterogeneous; however, the long-term impact warrants further investigation. Vulnerable populations, including indigenous people, individuals working at e-waste sites, firefighters, and individuals within certain age groups, such as children and elderly, are especially critical to be informed of risk of exposure.

Association between brominated flame retardants and risk of endocrine-related cancer: A systematic review and meta-analysis

BACKGROUND

The incidence of endocrine-related cancer, which includes tumors in major endocrine glands such as the breast, thyroid, pituitary, and prostate, has been increasing year by year. Various studies have indicated that brominated flame retardants (BFRs) are neurotoxic, endocrine-toxic, reproductive-toxic, and even carcinogenic. However, the epidemiological relationship between BFR exposure and endocrine-related cancer risk remains unclear.

METHODS

We searched the PubMed, Google Scholar, and Web of Science databases for articles evaluating the association between BFR exposure and endocrine-related cancer risk. The odds ratio (OR) and its corresponding 95% confidence interval (95% CI) were used to assess the association. Statistical heterogeneity among studies was assessed with the Q-test and I2 statistics. Begg's test was performed to evaluate the publication bias.

RESULTS

We collected 15 studies, including 6 nested case-control and 9 case-control studies, with 3468 cases and 4187 controls. These studies assessed the risk of breast cancer, thyroid cancer, and endocrine-related cancers in relation to BFR levels. Our findings indicate a significant association between BFR exposure in adipose tissue and an increased risk of breast cancer. However, this association was not observed for thyroid cancer. Generally, BFR exposure appears to elevate the risk of endocrine-related cancers, with a notable increase in risk linked to higher levels of BDE-28, a specific polybrominated diphenyl ether congener.

CONCLUSIONS

In conclusion, although this meta-analysis has several limitations, our results suggest that BFR exposure is a significant risk factor for breast cancer, and low-brominated BDE-28 exposure could significantly increase the risk of endocrine-related cancers. Further research is essential to clarify the potential causal relationships between BFRs and endocrine-related cancers, and their carcinogenic mechanisms.

Thyroid dysfunction caused by exposure to environmental endocrine disruptors and the underlying mechanism: A review

Thyroid disease has been rapidly increasing, but its causes remain unclear. At present, many studies have focused on the relationship between environmental endocrine disruptors (EEDs) and the pathogenesis of thyroid disease. Herein, we summarize such studies exploring the effects of exposure to common EEDs on thyrotoxicosis, finding that EEDs appear to contribute to the pathogenesis of thyroid-related diseases such as thyroid cancer, goiter, thyroiditis, hyperthyroidism, and hypothyroidism. To explore this causative effect in detail, we have analyzed the following three aspects of how EEDs are believed to exert their impacts on the occurrence and development of thyroid disease: (1) damage to the thyroid tissue structure, including disrupted mitochondria and the stratification of thyroid follicular epithelial cells; (2) disruption of thyroid hormone signaling, including thyroid hormone synthesis and secretion disorders, destruction of normal function of the hypothalamus-pituitary-thyroid axis, disturbed estrogen signaling in the body, alterations to the level of thyroid-stimulating hormone, inhibition of the release of thyroglobulin from thyroid cells, and reductions in the levels of sodium iodide co-transporters, thyroid peroxidase, deiodinase, and transthyretin; and (3) molecular mechanisms underlying the disruption of thyroid function, including competitive binding to T3 and T4 receptors, disturbance of the hypothalamic-pituitary-thyroid axis, activation of the ERK and Akt pathways, oxidative stress, regulation of the expression of the proto-oncogene k-Ras, tumor suppressor gene PTEN, and thyroid TSHR gene, and induction of autophagy in thyroid cells. Overall, this article reviews how EEDs can affect the occurrence and development of thyroid disease via multiple routes, thus providing new ideas to intervene for the prevention, diagnosis, treatment, and prognosis of thyroid disease.

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

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

Hesperidin partly ameliorates the decabromodiphenyl ether-induced reproductive toxicity in pubertal mice

Many materials use polybrominated diphenyl ethers (PBDEs) as flame retardants. As one of the most common congeners of PBDEs, decabromodiphenyl ether (PBDE-209) is reported to harm reproductive health. However, little is known research on attenuating the reproductive toxicity induced by PBDE-209. The present study aimed to investigate the effects of hesperidin against PBDE-209-induced reproductive toxicity in male mice. Pubertal male C57BL/6 J mice were exposed to PBDE-209 groups (20, 100, 500 mg/kg·bw) and hesperidin groups (100 mg/kg·bw PBDE-209 + 100 mg/kg·bw hesperidin) for 8 weeks. The results showed that PBDE-209 increased the amount of abnormal morphological sperms and decreased the sex hormone levels. PBDE-209 induced the histopathological lesions of seminiferous tubules and blood-testis barrier in mice testis. Expressions of apoptosis-associated proteins and mRNA (Bax, Bcl-2, etc.) were altered by the PBDE-209 treatment. PBDE-209 prominently increased the malondialdehyde (MDA) levels, the biomarker of oxidative stress. Hesperidin treatment partly alleviated PBDE-209-induced histopathological lesions and apoptosis in mice testis. These findings suggested that hesperidin partly protects against PBDE-induced reproductive toxicity in pubertal mice. We conclude that more work needs to be done to explore the appropriate dosage of hesperidin or find other drugs to protect against the reproductive toxicity of PBDEs.

BDE-47, -99, -209 and Their Ternary Mixture Disrupt Glucose and Lipid Metabolism of Hepg2 Cells at Dietary Relevant Concentrations: Mechanistic Insight through Integrated Transcriptomics and Proteomics Analysis

Polybrominated diphenyl ethers (PBDEs) are persistent organic chemicals implied as flame retardants. Humans are mainly exposed to BDE-47, -99, and -209 congeners by diet. PBDEs are metabolic disruptors with the liver as the main target organ. To investigate their mode of action at a human-relevant concentration, we exposed HepG2 cells to these congeners and their mixture at 1 nM, analyzing their transcriptomic and proteomic profiles. KEGG pathways and GSEA Hallmarks enrichment analyses evidenced that BDE-47 disrupted the glucose metabolism and hypoxia pathway; all the congeners and the MIX affected lipid metabolism and signaling Hallmarks regulating metabolism as mTORC1 and PI3K/AKT/MTOR. These results were confirmed by glucose secretion depletion and increased lipid accumulation, especially in BDE-47 and -209 treated cells. These congeners also affected the EGFR/MAPK signaling; further, BDE-47 enriched the estrogen pathway. Interestingly, BDE-209 and the MIX increased ERα gene expression, whereas all the congeners and the MIX induced ERβ and PPARα. We also found that PBDEs modulated several lncRNAs and that HNRNAP1 represented a central hub in all the four interaction networks. Overall, the PBDEs investigated affected glucose and lipid metabolism with different underlying modes of action, as highlighted by the integrated omics analysis, at a dietary relevant concentration. These results may support the mechanism-based risk assessment of these compounds in relation to liver metabolism disruption.

Associations between environmental exposure to polybrominated diphenyl ethers and nodular goiter risk: A case-control study

Polybrominated diphenyl ethers (PBDEs) are widespread and persistent environmental contaminants, but their association with nodular goiter (NG) remains unknown. The present case-control study of 179 NG cases and 358 matched normal controls aimed to investigate the association between PBDEs and risk of NG. The plasma concentrations of 8 PBDEs congeners (BDE-28, -47, -99, -100, -153, -154, -183, and -209) were determined by gas chromatograph-mass spectrometer. Conditional logistic regression model was used to evaluate the odds ratio (OR) and 95% confidence interval (CI) for the association between each PBDEs congener and NG. Bayesian kernel machine regression (BKMR) was used to evaluate the association between overall levels of 8 PBDEs mixture and NG. The results of logistic model suggested that increased risk of NG was associated with elevated concentrations of all PBDEs congeners, except for BDE-209. In BKMR model, the risk of NG increased with the increase in overall exposure level of 8 PBDEs mixture. Compared to when all PBDEs mixture were at their median value, the risk of exposure-response function for NG increased by 0.34 units when all PBDEs were at their 75th percentile. In women, the results showed similar trends after additional adjustment for age at menarche and menopausal status. These findings provide novel epidemiological evidence for the prevention of NG. However, larger prospective studies are required to address the associations between PBDEs exposure and NG risk.

Understanding the role of biochar in affecting BDE-47 biodegradation by Pseudomonas plecoglossicida: An integrated analysis using chemical, biological, and metabolomic approaches

Biochar-assisted microbial degradation technology is considered as an important strategy to eliminate organic pollutants, but the mechanism of biochar in affecting biodegradation has not been systematically studied. To address this knowledge gap, the effect of various biochars on biodegradation of different initial concentrations of BDE-47 by Pseudomonas plecoglossicida was investigated. The results showed that biochar exhibited significant promotion to the biodegradation of BDE-47, especially at concentrations of BDE-47 above 100 μg/L. The promotion effect was negatively influenced by the aromaticity and micropore volume of biochar. Biochar alleviated the cytotoxicity of BDE-47 to P. plecoglossicida and promoted cell proliferation based on toxicity assays. Additionally, biochar acted as shelter and stimulated the secretion of extracellular polymeric substances, which might support P. plecoglossicida to struggle with extreme conditions. Metabolomic analysis indicated that biochar resulted in upregulation expression of 38 metabolites in P. plecoglossicida. These upregulated metabolites were mainly related to glyoxylate and dicarboxylate metabolism, citrate cycle, and serial amino acid metabolism, suggesting that biochar could improve the BDE-47 biodegradation via enhancing oxidative metabolism and energy supply of the bacterial cells. This work elucidates how biochar can affect BDE-47 biodegradation and provides insights for the application prospect of biochar-assisted microbial degradation technology in the environment.

E-Waste in Africa: A Serious Threat to the Health of Children

Waste electronic and electrical equipment (e-waste) consists of used and discarded electrical and electronic items ranging from refrigerators to cell phones and printed circuit boards. It is frequently moved from developed countries to developing countries where it is dismantled for valuable metals in informal settings, resulting in significant human exposure to toxic substances. E-waste is a major concern in Africa, with large sites in Ghana and Nigeria where imported e-waste is dismantled under unsafe conditions. However, as in many developing countries, used electronic and electrical devices are imported in large quantities because they are in great demand and are less expensive than new ones. Many of these used products are irreparable and are discarded with other solid waste to local landfills. These items are then often scavenged for the purpose of extracting valuable metals by heating and burning, incubating in acids and other methods. These activities pose significant health risks to workers and residents in communities near recycling sites. E-waste burning and dismantling activities are frequently undertaken at e-waste sites, often in or near homes. As a result, children and people living in the surrounding areas are exposed, even if they are not directly involved in the recycling. While toxic substances are dangerous to individuals at any age, children are more vulnerable as they are going through important developmental processes, and some adverse health impacts may have long-term impacts. We review the e-waste situation in Africa with a focus on threats to children's health.

Roles of endoplasmic reticulum stress in 2,2',4,4'-tetrabromodiphenylether-induced thyroid cell apoptosis and autophagy

Polybrominated diphenyl ethers are known to be toxic and impair thyroid function. However, the underlying molecular mechanisms are not well understood. We constructed a female Sprague-Dawley rat model to evaluate the role of endoplasmic reticulum stress, apoptosis and autophagy in 2,2',4,4'-tetrabromodiphenylether (PBDE-47) induced thyroid toxicity. In the brain development spurt period (postnatal day 10), rats were treated with PBDE-47 (0, 1, 5, 10 mg/kg bw, i.g). Two addition groups were administered with 4-Phenylbutyric acid, an endoplasmic reticulum stress modulator, to reverse PBDE-47-induced thyroid toxicity. Our results demonstrated that PBDE-47 significantly decreased serum thyroid stimulating hormone levels, induced histologic changes in thyroid tissues, increased the percentage of cell apoptosis and expression levels of C/EBP-homologous protein, caspase 3, glucose-regulated protein 78, inositol-requiring enzyme 1, and autophagy-related proteins Beclin1 and 1A/1B-light chain 3. Besides of decreased serum thyroid stimulating hormone levels, all these changes were reversed by 4-Phenylbutyric acid. Taken together, these data indicate that, PBDE-47 damages the thyroid tissues by triggering endoplasmic reticulum stress, apoptosis and autophagy.

Polybrominated Diphenyl Ether Serum Concentrations and Depressive Symptomatology in Pregnant African American Women

(1) Polybrominated diphenyl ethers (PBDEs) were widely produced in the United States until 2004 but remain highly persistent in the environment. The potential for PBDEs to disrupt normal neuroendocrine pathways resulting in depression and other neurological symptoms is largely understudied. This study examined whether PBDE exposure in pregnant women was associated with antenatal depressive symptomatology. (2) Data were collected from 193 African American pregnant women at 8–14 weeks gestation. Serum PBDEs and depressive symptoms were analyzed and a mixture effect was calculated. (3) Urban pregnant African American women in the Southeastern United States had a high risk of depression (27%) compared to the National average. Increased levels of PBDEs were found. BDE-47 and -99 exposures are significantly associated with depressive symptomatology in the pregnant cohort. The weighted body burden estimate of the PBDE mixture was associated with a higher risk of mild to moderate depression using an Edinburgh Depression Scale cutoff score of ≥10 (OR = 2.93; CI 1.18, 7.82). (4) Since antenatal depression may worsen in postpartum, reducing PBDE exposure may have significant clinical implications.

Dietary Intake of Endocrine Disrupting Substances Presents in Environment and Their Impact on Thyroid Function

According to the available data, environmental pollution is a serious problem all over the world. Between 2015 and 2016, pollution was responsible for approximately nine million deaths worldwide. They also include endocrine disrupting chemicals (EDCs) that can interfere with the functioning of the thyroid gland. They are characterized by high persistence in the environment. These substances can enter the body through the gastrointestinal tract, respiratory system, as well as contact with the skin and overcome the placental barrier. EDC can be found in food, water, and personal care products. They can get into food from the environment and as a result of their migration to food products and cosmetics from packaging. EDCs can disrupt the functioning of the thyroid gland through a number of mechanisms, including disrupting the activation of thyroid receptors and the expression of genes that are related to the metabolism, synthesis, and transport of thyroid hormones (HT). There is a need to strengthen the food safety policy that aimed at the use of appropriate materials in direct contact with food. At the same time, an important action is to reduce the production of all waste and, when possible, use biodegradable packaging, which may contribute to the improvement of the quality of the entire ecosystem and the health of food, thus reducing the risk of developing thyroid diseases.

Polybrominated diphenyl ethers in serum from residents living in a brominated flame retardant production area: Occurrence, influencing factors, and relationships with thyroid and liver function

Polybrominated diphenyl ethers (PBDEs) have been used as flame retardants (FRs) in China for decades, even after they were identified as persistent organic pollutants. In this study, serum samples were collected from 172 adults without occupational exposure who were residents of a well-known FR production region (Laizhou Bay, north China), and PBDE congeners were measured to assess their occurrence, congener profile and influencing factors in serum. Moreover, the relationships between serum concentrations of PBDEs and thyroid/liver function indicators were analyzed to evaluate whether human exposure to PBDEs would lead to thyroid/liver injury. All 8 PBDE congeners were detected at higher frequencies and serum concentrations than those found in general populations. The median levels of ∑PBDEs, BDE-209 and ∑_3-7PBDEs (sum of tri-to hepta-BDEs) were 64.5, 56.9 and 7.2 ng/g lw (lipid weight), respectively, which indicated that deca-BDE was the primarily produced PBDE in Laizhou Bay and that the lower brominated BDEs were still ubiquitous in the environment. Gender was a primary influencing factor for some BDE congeners in serum; their levels in female serum samples were significantly lower than those in male serum samples. Serum PBDE levels showed a downward trend with increased body mass index (BMI), which might reflect the increasing serum lipid contents. Serum levels of some BDE congeners were significantly positively correlated with certain thyroid hormones and antibodies, including free triiodothyronine (fT3), total triiodothyronine (tT3), total thyroxine (tT4) and thyroid peroxidase antibody (TPO-Ab). Levels of some congeners were significantly negatively correlated with some types of serum lipid, including cholesterol (CHOL), low density lipoprotein (LDL) and total triglyceride (TG). Other than serum lipids, only two liver function indicators, total protein (TP) and direct bilirubin (DBIL), were significantly correlated with certain BDE congeners (BDE-100 and BDE-154). Our results provide new evidence on the thyroid-disrupting and hepatotoxic effects of PBDEs.

Changes in thyroid hormone related proteins and gene expression induced by polychlorinated biphenyls and halogen flame retardants exposure of children in a Chinese e-waste recycling area

Polychlorinated biphenyls (PCBs) and halogen flame retardants (HFRs) are major pollutants in e-waste recycling area. High internal exposure levels of PCBs and HFRs are harmful to human thyroid hormone (TH) equilibrium. To examine their disrupting effects on TH, we conducted a study on children (n = 114) of an e-waste recycling and a control area in South China. Concentrations of PCBs, HFRs, and TH levels were determined in serum samples. TH related proteins and their corresponding gene were also monitored as markers of such disruption. Levels of these chemicals in the exposed group were much greater than those in the control group. Results of the linear regression and generalized additive model indicated the presence of close relationships between the internal exposure levels and the responses of TH related proteins, gene expression. More extensive exposure concentrations of these chemicals led to higher expression of iodothyronine deiodinase I and decreased the concentrations of thyroid-stimulating hormone, expression of TH receptor α, indicating the exertion of discrepant and even contrary influences on equilibrium of TH, and a compensation of these mechanisms may kept the homeostasis of TH. These results for children warrant further investigation on the health risks of PCBs and HFRs exposure in e-waste area.

Understanding the role of bacterial cellular adsorption, accumulation and bioavailability regulation by biosurfactant in affecting biodegradation efficacy of polybrominated diphenyl ethers

Microbiological degradation is often considered as an important strategy to reduce the risks of polybrominated diphenyl ethers (PBDEs), which are environmentally widespread and harmful to human health and wildlife. With the well-identified aerobic bacteria, i.e. B. xenovorans LB400, the biodegradation of 2,2',4,4'-tetrabrominated diphenyl ether (BDE-47) occurred efficiently in conformity to the first-order kinetics and showed the strong dependence on initial concentration of pollutant and bioavailability regulation by biosurfactant. The mild increase of initial concentration of BDE-47 would enhance biodegradation whereas the excessive increase failed due to the oxidative stress or cytotoxicity to bacteria. Rather than the bacterial extracellular adsorption that was bioactively-mediated in thermodynamics, the intracellular accumulations at different time gradients showed the negative correlation with biodegradation efficiency of BDE-47. The spontaneous biodegradation of pollutant should be sourced from the gradual reduction of intracellular accumulation. Though the improved bioavailability of BDE-47 by sucrose fatty acid ester (SFAE) hardly altered the extracellular adsorption, the bacterial intracellular accumulation was indicated to increase continuously with used amount of biosurfactant and then decrease for the cellular morphological damage, and interestingly it appeared to be temporary reservoir for prompt delivery to biodegradation in light of the opposite variation tendency with time.

Effect of gestational and lactational nonylphenol exposure on airway inflammation in ovalbumin-induced asthmatic rat pups

To investigate the effect of gestational and lactational nonylphenol (NP) exposure on airway inflammation in ovalbumin (OVA)-induced asthmatic pups. Dams were gavaged with NP at dose levels of 25 mg/kg/day (low dose), 50 mg/kg/day (middle dose), 100 mg/kg/day (high dose) and groundnut oil alone (vehicle control) respectively from gestational day 7 to postnatal day 21. The results showed that the NP content in the lung tissues of pups in the 100 mg/kg NP group was significantly higher than that of the control group (P = 0.004). In the 100 mg/kg NP group, the infiltration of lymphocytes and eosinophils with thicken smooth muscle layer and inflammatory cells in the lumen were observed in the lung tissues of pups. Osmiophilic lamellar bodies were found in the cytoplasm of type II epithelial cells; mitochondria were clearly swollen. Compared with the control group, the levels of interleukin-4 (IL-4) in BALF (P = 0.042) and ovalbumin-specific serum immunoglobulin E (OVA-sIgE) (P = 0.005) in the OVA group were significantly higher. 25 mg/kg NP-OVA co-exposure synergistically decreased nuclear factor-κB (NF-κB) mRNA expression in the lung tissues of pups; Exposure to 50 mg/kg NP combined with OVA antagonized the increased expression of high mobility group box 1 (HMGB1) mRNA in the lung tissue. The combined exposure to 50 mg/kg NP and OVA synergistically increased HMGB1 protein expression in the lung tissues. 25 mg/kg NP-OVA co-exposure antagonized the increased nuclear factor-κB (NF-κB) protein expression in the lung tissues. There was a positive correlation between NP content and HMGB1 protein expression in the lung tissue of asthmatic pups (r = 0.602, P < 0.001). In conclusion, gestational and lactational exposure to 100 mg/kg NP in maternal rats exacerbated airway inflammation in OVA-induced asthmatic pups, and there is an interactive effect between NP and OVA. When the perinatal rats were exposed to 100 mg/kg NP, the levels of HMGB1 and NF-κB in the lung tissues of OVA-induced asthmatic pups were increased.

Hepatic Transcriptomic Patterns in the Neonatal Rat After Pentabromodiphenyl Ether Exposure

Human exposure to pentabromodiphenyl ether (PBDE) mixture (DE-71) and its PBDE-47 congener can occur both in utero and during lactation. Here, we tested the hypothesis that PBDE-induced neonatal hepatic transcriptomic alterations in Wistar Han rat pups can inform on potential toxicity and carcinogenicity after longer term PBDE exposures. Wistar Han rat dams were exposed to either DE-71 or PBDE-47 daily from gestation day (GD 6) through postnatal day 4 (PND 4). Total plasma thyroxine (T4) was decreased in PND 4 pups. In liver, transcripts for CYPs and conjugation enzymes, Nrf2, and ABC transporters were upregulated. In general, the hepatic transcriptomic alterations after exposure to DE-71 or PBDE-47 were similar and provided early indicators of oxidative stress and metabolic alterations, key characteristics of toxicity processes. The transcriptional benchmark dose lower confidence limits of the most sensitive biological processes were lower for PBDE-47 than for the PBDE mixture. Neonatal rat liver transcriptomic data provide early indicators on molecular pathway alterations that may lead to toxicity and/or carcinogenicity if the exposures continue for longer durations. These early toxicogenomic indicators may be used to help prioritize chemicals for a more complete toxicity and cancer risk evaluation.

Higher health risk resulted from dermal exposure to PCBs than HFRs and the influence of haze

To investigate the influence of haze on human dermal exposure to a series of halogenated flame retardants (HFRs) and polychlorinated biphenyls (PCBs), paired forehead wipes were collected from 46 volunteers (23 males, 23 females) using gauze pads soaked in isopropyl alcohol under heavy and light haze pollution levels. The median levels of ∑₂₇HFRs and ∑₂₇PCBs in all 92 samples were 672 and 1300ng/m², respectively. Decabromodiphenyl ether (BDE-209) (171ng/m²) and decabromodiphenylethane (DBDPE) (134ng/m²) were the dominant components of HFRs, indicating that dermal exposure may also be the significant pathway for non-volatile compounds. PCB-37 contributed the most to ∑₂₇PCBs, with a median concentration of 194ng/m², followed by PCB-60 (141ng/m²). Generally, PBDE, PCB and DD (dehalogenated derivatives of DPs) levels on the foreheads of female participants (291, 1340, 0.92ng/m²) were higher (p=0.037, 0.001, and 0.031, respectively) than those of male participants (226, 989, and 0.45ng/m²). A significant difference (p=0.001) in PCBs was found between light (1690ng/m²) and heavy (996ng/m²) haze pollution conditions. Nevertheless, HFR levels under heavy (median=595ng/m², ranging from 295 to 1490ng/m²) and light haze pollution conditions (ranging from 205 to 1220ng/m² with a median of 689ng/m²) did not show significant differences (p=0.269). The non-carcinogenic health risk resulting from dermal exposure to ∑₈HFRs and ∑₂₇PCBs was 8.72×10^-5 and 1.63×10^-2, respectively, raising more concern about populations' exposure to PCBs than HFRs.

PBDE serum concentration and preschool maturity of children from Slovakia

Polybrominated diphenylethers (PBDEs) are persistent organic pollutants (POPs), they are considered endocrine disruptors and can bioaccumulate in nature, and in living tissue. Human exposure to and the presence of PBDEs in human samples is of concern due to their potential health risks. Young children are one of the most vulnerable populations to PBDE's potential health effects. Ninety-one serum samples of 6-year-old children, residing in a contaminated location, due to former production of polychlorinated biphenyls (PCBs), were analysed to examine children's exposure to PBDEs in Slovakia. Median serum concentrations found for individual PBDE congeners BDE-28⁺³³, -47, -99, -100, -153, -154 and -183 were 0.015, 0.184, 0.079, 0.046, 0.176, 0.014, and 0.097 ng g^-1 lipid weight, respectively. Children's preschool maturity was measured using the Wechsler Preschool and Primary Scale of Intelligence (WPPSI-III) test. In multivariate analyses BDE-153 serum concentrations were significantly inversely associated with WPPSI-III composite score (p = 0.011, β = -23.6), while adjusting for PCB-153 and sex. Significant negative associations were observed for BDE-153 serum concentrations (p = 0.002, β = -29.8) and WPPSI-III composite score, after controlling for PCB-118 and sex. Negative associations were also observed for BDE-47, BDE-100 and BDE-153, with different individual WPPSI subtest scores, after adjustment with PCB-153 and/or PCB-118 and sex. Serum concentrations of PCB-153 and PCB-118 were not statistically significantly associated with WPPSI-III composite score and individual subtest scores. These findings demonstrate adverse effects of PBDE serum exposure on preschool maturity of children, and PBDEs potentially negative impact on child neuropsychological development.

Degradation of 2,2',4,4'-tetrabromodiphenyl ether by Pycnoporus sanguineus in the presence of copper ions

The degradation of 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) by Pycnoporus sanguineus was investigated in order to explore the impact of the heavy metal Cu²⁺ on BDE-47 decomposition and the subsequent formation of metabolites, as well as to further elucidate the degradation mechanism of BDE-47. An increase in degradation rate from 18.63% to 49.76% in the first four days and its stabilization at (51.26 ± 0.08)% in the following days of BDE-47 incubation were observed. The presence of Cu²⁺ at 1 and 2 mg/L was found to promote the degradation rate to 56.41% and 60.79%, respectively, whereas higher level of Cu²⁺ (≥5 mg/L) inhibited the removal of BDE-47. The similar concentration effects of Cu²⁺ was also found on contents of fungal protein and amounts of metabolites. Both intracellular and extracellular enzymes played certain roles in BDE-47 transportation with the best degradation rate at 27.90% and 27.67% on the fourth and third day, individually. During the degradation of BDE-47, four types of hydroxylated polybrominated diphenyl ethers (OH-PBDEs), i.e., 6'-OH-BDE-47, 5'-OH-BDE-47, 4'-OH-BDE-17, 2'-OH-BDE-28, and two bromophenols, i.e., 2,4-DBP and 4-BP were detected and considered as degradation products. These metabolites were further removed by P. sanguineus at rates of 22.42%, 23.01%, 27.04%, 27.96%, 64.21%, and 40.62%, respectively.

Establishment of a human embryonic stem cell-based liver differentiation model for hepatotoxicity evaluations

The liver is one of the major targets of hormones, including thyroid hormones (THs), and many industrial chemicals, such as endocrine-disrupting chemicals. Those compounds may permeate the placenta barrier and pose a risk for embryonic development. Therefore, it is necessary to assess the toxic effects of those kind of industrial chemicals during liver development. In this study, to mimic liver specification in vitro, we differentiated human embryonic stem cells (ESCs) into functional hepatocyte-like cells. We performed this differentiation process in presence of two THs, triiodothyronine (T3) and thyroxine (T4), with the purpose of identifying biomarkers for toxicity screening. TH exposure (3, 30 and 300 nM) yielded to hepatocytes with impaired glycogen storage ability and abnormal lipid droplets' accumulation. Global gene expression analysis by RNA-seq identified a number of genes responsible for hepatic differentiation and function which were affected by 30 nM T3 and T4. Those differentially expressed genes were used to assess the potential developmental liver toxicity of two famous environmental pollutants, 2, 2, 4, 4-tetrabromodiphenyl ether (BDE-47) and decabromodiphenyl ether (BDE-209), at 10 nM to 1 μM treatments. Our findings demonstrate that BDE-47 and BDE-209, dysregulated pathways such as "chemical carcinogenesis", "steroid hormone biosynthesis" and "drug metabolism-cytochrome P450". Moreover, we were able to identify a set of 17 biomarkers, very useful to predict the potential developmental hepatotoxicity of industrial chemicals.

Pre- and Postnatal Polybrominated Diphenyl Ether Concentrations in Relation to Thyroid Parameters Measured During Early Childhood

Background: Penta-brominated diphenyl ethers (PentaBDEs) are endocrine-disrupting chemicals that structurally resemble thyroid hormones and were widely used as flame retardants in household consumer products from 1975 to 2004. Polybrominated diphenyl ethers (PBDEs) cross the placenta, and evidence suggests that for many children, body burdens may peak during the toddler years. This study aimed to understand the impact of exposure timing by examining both pre- and postnatal exposure to BDE-47, the predominant penta-brominated diphenyl ether congener detected in humans, in relation to thyroid hormone parameters measured during early childhood. Methods: The Columbia Center for Children's Environmental Health Mothers and Newborns Study is a prospective birth cohort of African American and Dominican maternal-child pairs. Pregnant women were recruited from two prenatal clinics in Northern Manhattan and the South Bronx between 1998 and 2006. Participants included 158 children with (i) plasma PBDE concentrations measured at birth and in the toddler years (age 2-3 years), and (ii) serum thyroid parameters measured at three and/or five years of age. Outcomes included concentrations of serum thyrotropin, free thyroxine, and total thyroxine. Results: Children with high exposure to BDE-47 during the prenatal period (-17% [confidence interval -29 to -2]) or toddler age (-19% [confidence interval -31 to -5]) had significantly lower geometric mean thyrotropin levels compared to children with low BDE-47 exposure throughout early life. Associations with thyroxine were also inverse; however, they did not reach statistical significance at the p = 0.05 level. Sex-stratified models suggest associations with postnatal exposure may be stronger among boys compared to girls. Conclusions: The thyroid regulatory system may be sensitive to BDE-47 during pre- and postnatal periods.

Exposure to polybrominated biphenyl (PBB) associates with genome-wide DNA methylation differences in peripheral blood

In 1973, Michigan residents were exposed to polybrominated biphenyl (PBB) when it was accidentally added to farm animal feed. Highly exposed individuals and their children have experienced endocrine-related health problems, though the underlying mechanism behind these remains unknown. We investigated whether PBB exposure is associated with variation in DNA methylation in peripheral blood samples from 658 participants of the Michigan PBB registry using the MethylationEPIC BeadChip, as well as investigated what the potential function of the affected regions are and whether these epigenetic marks are known to associate with endocrine system pathways. After multiple test correction (FDR <0.05), 1890 CpG sites associated with total PBB levels. These CpGs were not enriched in any particular biological pathway, but were enriched in enhancer and insulator regions, and depleted in regions near the transcription start site or in CpG islands (p < 0.05). They were also more likely to be in ARNT and ESR2 transcription factor binding sites (p = 3.27e-23 and p = 1.62e-6, respectively), and there was significant overlap between CpGs associated with PBB and CpGs associated with estrogen (p < 2.2e-16). PBB-associated CpGs were also enriched for CpGs known to be associated with gene expression in blood (eQTMs) (p < 0.05). These eQTMs were enriched for pathways related to immune function and endocrine-related autoimmune disease (FDR <0.05). These results indicate that exposure to PBB is associated with differences in epigenetic marks that suggest that it is acting similarly to estrogen and is associated with dysregulated immune system pathways.

Childhood polybrominated diphenyl ether (PBDE) serum concentration and reading ability at ages 5 and 8 years: The HOME Study

BACKGROUND

Polybrominated diphenyl ethers (PBDEs) exist extensively in the environment and human beings. PBDE concentrations are higher in children than adults. A previous study found that prenatal PBDE exposure was associated with decreased reading skills in children; however, evidence is limited on the potential impact of childhood exposure to PBDEs. The study examined the association between childhood PBDE exposures and reading ability in children at ages 5 and 8 years.

METHODS

The study included 230 children from an ongoing prospective pregnancy and birth cohort study, the Health Outcomes and Measures of Environment (HOME) Study, conducted in Cincinnati, Ohio. Children's serum concentrations of eleven PBDE congeners were measured at 1, 2, 3, 5, and 8 years. The Woodcock-Johnson Tests of Achievement - III and the Wide Range Achievement Test - 4 were administered to assess children's reading skills at ages 5 and 8 years, respectively. We used multiple informant models to examine the associations between repeated measures of PBDEs and reading scores at ages 5 and 8 years. We also estimated the βs and 95% CIs of the association of PBDE measure at each age by including interaction terms between PBDE concentrations and child age in the models.

RESULTS

All childhood BDE-153 concentrations were inversely associated with reading scores at 5 and 8 years, but associations were not statistically significant after covariate adjustment. For example, a 10-fold increase in BDE-153 concentrations at ages 3 and 5 years was associated with a -5.0 (95% confidence interval (CI): -11.0, 1.0) and -5.5 (95% CI: -12.5, 1.4) point change in Basic Reading score at age 5 years, respectively. Similarly, the estimates for Brief Reading score at age 5 years were -4.5 (95% CI: -10.5, 1.5) and -5.2 (95% CI: -12.2, 1.7) point changes, respectively. Serum concentration of BDE-47, -99, -100, and Sum₄PBDEs (sum of BDE-47, 99, 100, and 153) at every age were inversely associated with reading scores at ages 5 and 8 years in unadjusted analyses. While the adjusted estimates were much attenuated and became non-significant, the direction of most of the associations was not altered.

CONCLUSION

Our study has shown a suggestive but non-significant trend of inverse associations between childhood PBDE serum concentrations, particularly BDE-153, and children's reading skills. Future studies with a larger sample size are needed to examine these associations.

Temporal trends and developmental patterns of plasma polybrominated diphenyl ether concentrations over a 15-year period between 1998 and 2013

Polybrominated diphenyl ethers (PBDEs) were used extensively as flame retardants in furniture containing polyurethane foam until they were phased out of use, beginning in 2004. We examined temporal changes in plasma PBDE concentrations from 1998 to 2013 and characterized patterns of exposure over the early lifecourse among 334 children (903 samples) between birth and 9 years. We examined time trends by regressing PBDE concentration on year of sample collection in age-adjusted models and characterized developmental trajectories using latent class growth analysis (LCGA). Controlling for age, BDE-47 concentrations decreased 5% (95% confidence interval (CI): -9, -2) per year between 1998 and 2013. When considering only postnatal samples, this reduction strengthened to 13% (95% CI: -19, -9). Findings for BDE-99, 100 and 153 were similar, except that BDE-153 decreased to a lesser extent when both prenatal and postnatal samples were considered (-2%, 95% CI: -7, 0). These findings suggest that, on average, pentaBDE body burdens have decreased since the 2004 phase-out of these chemicals. When examining developmental period, PBDE concentrations peaked during toddler years for the majority of children, however, our observation of several unique trajectories suggests that a single measure may not accurately reflect exposure to PBDEs throughout early life.

Temporal trends in serum polybrominated diphenyl ether concentrations in the Australian population, 2002-2013

In Australia, systematic biomonitoring of persistent organic pollutants (POPs) in pooled serum samples stratified by age and sex has occurred every two years between 2002/03 and 2012/13. Multiple regression modeling on log10-transformed serum pool concentrations of BDEs 47, 99, 100 and 153 and on the sum of these (Σ₄PBDE) was conducted to examine trends by sex and time since baseline, stratified by age group. Temporal trends were age- and congener-specific, with the largest changes per year of observation in the 0-4 year old group, with β (SE) = -0.098 (0.013) for log₁₀BDE47; -0.119 (0.012) for log₁₀BDE99; -0.084 (0.014) for log₁₀BDE100, and -0.053 (0.013) for log₁₀BDE153, all p < 0.001. Adults over age 16 showed much smaller decreasing temporal trends for BDE47 and BDE99, no significant changes in BDE100, and, for the oldest age groups, slight increases in BDE153. As a result, Σ₄PBDE concentrations were stable over the entire time period in adults older than 16. Concentrations of each BDE in pools from females aged 31-60 were significantly lower compared to males. Relative proportions of BDE47 declined, while BDE153 accounted for a greater share of Σ₄PBDE over time. Whereas previously we saw a large elevation in the youngest age groups compared to older children and adults, this is no longer the case. This may be due to a decline in infant and toddler exposures in the indoor environment as use of PBDEs in consumer products has been phased out, suggesting temporal changes in the relative sources of exposure for young children in Australia.

Spatial Distribution of Novel and Legacy Brominated Flame Retardants in Soils Surrounding Two Australian Electronic Waste Recycling Facilities

Informal recycling of electronic waste (e-waste) has been shown to cause significant brominated flame retardant (BFR) contamination of surrounding soils in a number of Asian and West African countries. However, to the authors' knowledge, there have been no published studies demonstrating polybrominated diphenyl ether (PBDE) and novel brominated flame retardant (NBFR) soil contamination from regulated "formal" e-waste processing facilities in developed countries. This study reports on PBDEs (-28, -47, -99, -100, -153, -154, -183, and -209) and NBFRs (PBT, PBEB, HBB, EH-TBB, BTBPE and DBDPE) in 36 soil samples surrounding two Australian e-waste recycling plants and a further eight reference soils. Overall ∑PBDE concentrations ranged 0.10-98 000 ng/g dw (median; 92 ng/g dw) and ∑NBFRs ranged ND-37 000 ng/g dw (median 2.0 ng/g dw). Concentrations in soils were found to be significantly negatively associated with distance from one of the e-waste facilities for ∑penta-BDEs, BDE-183, BDE-209, and ∑NBFR compound groups. ANOVA tests further illustrated the potential for e-waste recycling to significantly elevate concentrations of some BFRs in soils over distances up to 900 m compared to references sites. This study provides the first evidence of soil contamination with PBDEs and NBFRs originating from formal e-waste recycling facilities in Australia, which may have implications for e-waste recycling practices throughout the world.

Polybrominated diphenyl ether (PBDE) exposures and thyroid hormones in children at age 3 years

BACKGROUND

Polybrominated diphenyl ethers (PBDEs) reduce serum thyroid hormone concentrations in animal studies, but few studies have examined the impact of early-life PBDE exposures on thyroid hormone disruption in childhood.

METHODS

We used data from 162 mother-child pairs from the Health Outcomes and Measures of the Environment Study (2003-2006, Cincinnati, OH). We measured PBDEs in maternal serum at 16 ± 3 weeks gestation and in child serum at 1-3 years. Thyroid hormones were measured in serum at 3 years. We used multiple informant models to investigate associations between prenatal and early-life PBDE exposures and thyroid hormone levels at age 3 years.

RESULTS

Prenatal PBDEs were associated with decreased thyroid stimulating hormone (TSH) levels at age 3 years. A 10-fold increase in prenatal ∑PBDEs (BDE-28, -47, -99, -100, and -153) was associated with a 27.6% decrease (95% CI -40.8%, -11.3%) in TSH. A ten-fold increase in prenatal ∑PBDEs was associated with a 0.25 pg/mL (0.07, 0.43) increase in free triiodothyronine (FT3). Child sex modified associations between prenatal PBDEs and thyroid hormones, with significant decrements in TSH among females and decreased free T4 (FT4) in males. Prenatal ∑PBDEs were not associated with TT4, FT4, or total T3.

CONCLUSIONS

These findings suggest an inverse relationship between prenatal ∑PBDEs and TSH at 3 years. Associations may be sexually dimorphic, with an inverse relationship between prenatal BDE-47 and -99 and TSH in females and null associations among males.

Food Additives and Child Health

Our purposes with this policy statement and its accompanying technical report are to review and highlight emerging child health concerns related to the use of colorings, flavorings, and chemicals deliberately added to food during processing (direct food additives) as well as substances in food contact materials, including adhesives, dyes, coatings, paper, paperboard, plastic, and other polymers, which may contaminate food as part of packaging or manufacturing equipment (indirect food additives); to make reasonable recommendations that the pediatrician might be able to adopt into the guidance provided during pediatric visits; and to propose urgently needed reforms to the current regulatory process at the US Food and Drug Administration (FDA) for food additives. Concern regarding food additives has increased in the past 2 decades, in part because of studies in which authors document endocrine disruption and other adverse health effects. In some cases, exposure to these chemicals is disproportionate among minority and low-income populations. Regulation and oversight of many food additives is inadequate because of several key problems in the Federal Food, Drug, and Cosmetic Act. Current requirements for a "generally recognized as safe" (GRAS) designation are insufficient to ensure the safety of food additives and do not contain sufficient protections against conflict of interest. Additionally, the FDA does not have adequate authority to acquire data on chemicals on the market or reassess their safety for human health. These are critical weaknesses in the current regulatory system for food additives. Data about health effects of food additives on infants and children are limited or missing; however, in general, infants and children are more vulnerable to chemical exposures. Substantial improvements to the food additives regulatory system are urgently needed, including greatly strengthening or replacing the "generally recognized as safe" (GRAS) determination process, updating the scientific foundation of the FDA's safety assessment program, retesting all previously approved chemicals, and labeling direct additives with limited or no toxicity data.

Spatiotemporal variability of polybrominated diphenyl ether concentration in atmospheric fine particles in Shenzhen, China

Polybrominated diphenyl ethers (PBDEs) are widely used as flame retardants for various products and have become ubiquitous pollutants in environmental media. However, little is known about PBDE levels in Shenzhen, a manufacturing center of electronic products. This study aimed to investigate spatiotemporal variability of PBDE concentration in atmospheric fine particles (PM_2.5) and to estimate the daily inhalation exposure doses for local residents in Shenzhen, China. A total of 36 samples were collected and 8 PBDE compounds (BDE-28, 47, 99, 100, 153, 154, 183 and 209) were analyzed by isotope dilution high-resolution gas chromatograph/high-resolution mass spectrometer (HRGC/HRMS). Mean concentrations of Σ₈PBDEs and BDE-209 in PM_2.5 in Shenzhen were 33.47 pg/m³ and 24.75 pg/m³, respectively, which were lower than those for other reported cities from China. The mean concentration of Σ₈PBDEs was higher in the winter + spring than that in summer + autumn, and both concentrations of BDE-28 and BDE-47 in PM_2.5 were significantly higher in winter + spring than those in summer + autumn. Among the 8 congeners, BDE-209 was predominant, accounting for 73.9% of the Σ₈PBDEs concentrations. Traffic area, industrial area, residential area and discharge of electronic industries had significant positive influences on PBDE concentrations in PM_2.5. Both vegetation area and water area were significantly negatively correlated with PBDE levels in PM_2.5. Significantly negative correlation was also found between PBDE concentrations in PM_2.5 and the relative humidity. The ranking of estimated inhalation exposure doses of PBDEs via PM_2.5 inhalation were toddlers (1.74 pg/kg b.w./day) > children (1.33 pg/kg b.w./day) > adults (1.26 pg/kg b.w./day) > teenagers (0.64 pg/kg b.w./day), and toddlers had a highest risk to expose to PBDEs by PM_2.5. To our knowledge, the present study is the first to reveal the spatiotemporal variability of PBDEs in PM_2.5 of Shenzhen, China.

Association between serum polybrominated diphenyl ethers, new flame retardants and thyroid hormone levels for school students near a petrochemical complex, South China

As surrogates of polybrominated diphenyl ethers (PBDEs), new flame retardants (NFRs) include a series of chlorinated and brominated flame retardants. Though the NFRs are thought to induce similar thyroid hormone (TH) disrupting effects as PBDEs, few studies have focused on them. Given the increasing levels of NFRs in the environment, more in depth investigation of the potential TH disrupting effects of NFRs is warranted. This research involved a health survey to collect data and examine the associations between PBDEs, NFRs and TH. 174 school students lived near a petrochemical complex in South China participated in the survey, completing questionnaires and providing blood samples. Thirteen congeners of PBDEs, eight species of NFRs, TH and thyroid-stimulating hormone (TSH) were measured. The median levels of ΣPBDE (sum of thirteen congeners of PBDEs) and ΣNFR (sum of eight species of NFRs) for students were 140 and 240 ng g^-1 lipid, respectively. Nonmonotonic relationships were observed between quartile levels of PBDEs, NFRs and corresponding TH. In contrast to ΣPBDE that was positively associated with triidothyrine (T₃) level, ΣNFR was not statistically associated with TH. ΣPBDE + NFR (sum of thirteen congeners of PBDEs and eight species of NFRs) was significantly associated with T₃ level.

Methods of Responsibly Managing End-of-Life Foams and Plastics Containing Flame Retardants: Part I

Flame retardants (FRs) are added to foams and plastics to comply with flammability standards and test requirements in products for household and industrial uses. When these regulations were implemented, potential health and environmental impacts of FR use were not fully recognized or understood. Extensive research in the past decades reveal that exposure to halogenated FRs, such as those used widely in furniture foam, is associated with and/or causally related to numerous health effects in animals and humans. While many of the toxic FRs have been eliminated and replaced by other FRs, existing products containing toxic or potentially toxic chemical FRs will remain in use for decades, and new products containing these and similar chemicals will permeate the environment. When such products reach the end of their useful life, proper disposal methods are needed to avoid health and ecological risks. To minimize continued human and environmental exposures to hazardous FR chemicals from discarded products, waste management technologies and processes must be improved. This review discusses a wide range of issues associated with all aspects of the use and responsible disposal of wastes containing FRs, and identifies basic and applied research needs in the areas of responsible collection, pretreatment, processing, and management of these wastes.

Chemical Contaminants in Raw and Pasteurized Human Milk

BACKGROUND

Environmental contaminants ranging from legacy chemicals like p,p'-dichlorodiphenyltrichloroethane (DDT) to emerging chemicals like phthalates are ubiquitous. Research aims/questions: This research aims to examine the presence and co-occurrence of contaminants in human milk and effects of pasteurization on human milk chemical contaminants.

METHODS

We analyzed human milk donated by 21 women to a milk bank for 23 chemicals, including the persistent organic pollutants (POPs) polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), dichlorodiphenyltrichloroethane (DDT), and dichlorodiphenyldichloroethylene (DDE) isomers that are known to sequester in adipose tissue, along with the current-use and nonpersistent pesticides chlorpyrifos and permethrin, phthalates, and bisphenol A (BPA). Human milk was analyzed raw and pasteurized for these chemicals using gas chromatography-tandem mass spectrometry for the POPs and high-performance liquid chromatography-tandem mass spectrometry for non-POPs.

RESULTS

Within the different chemical classes, PBDE47, PCB153, ppDDE, and MEHHP (phthalate metabolite) had the highest median concentrations and were observed in all samples. We also observed chlorpyrifos and BPA in all samples and permethrin in 90% of the samples tested. Only two chemicals, chlorpyrifos and permethrin, were susceptible to substantial degradation from pasteurization, a standard method for processing donated human milk.

CONCLUSION

We detected 19 of 23 chemicals in all of our prepasteurized milk and 18 of 23 chemicals in all of our pasteurized milk. Pasteurization did not affect the presence of most of the chemicals. Future research should continue to explore human milk for potential chemical contamination and as a means to surveil exposures among women and children.

Concentrations of legacy and novel brominated flame retardants in indoor dust in Melbourne, Australia: An assessment of human exposure

Polybrominated diphenyl ethers (PBDEs) and novel brominated flame retardants (NBFR) have been used in a range of polymers to inhibit the spread of fires but also have a propensity to migrate out of consumer materials and contaminate indoor dust. In this study, a total of 57 dust samples were collected from 12 homes, eight offices and eight vehicles in Melbourne, Australia and analysed for eight PBDEs (-28, -47, -99, -100, -153, -154, -183 and -209) and seven NBFRs (PBT, PBEB, HBB, EH-TBB, BEH-TEBP, BTBPE and DBDPE) to determine human exposure risks from dust ingestion. Samples were analysed using selective pressurized liquid extraction (S-PLE) and gas chromatography coupled to tandem mass spectrometry (GC-MS/MS). Legacy and replacement flame retardants were detected in all samples with overall ∑PBDE concentrations ranging from 120 to 1700,000 ng/g (median 2100 ng/g) and ∑NBFRs ranging from 1.1 to 10,000 ng/g (median 1800 ng/g). BDE-209 and DBDPE were the dominant compounds in dust samples, followed by congeners associated with commercial Penta-BDE formulations (-47, -99, -100, -153 and -154) and then EH-TBB of the FireMaster 550 and BZ-54 products. ∑Penta-BDE concentrations were elevated in office samples compared with homes and vehicles, while EH-TBB and BDE-209 measured higher concentrations in vehicles compared with their respective levels in homes and offices. Risk assessment estimates revealed the majority of exposure to occur in the home for both adults and toddlers in the City of Melbourne. Generally, body weight adjusted exposure to PBDEs and NBFRs was predicted to be 1 to 2 orders of magnitude higher for toddlers than adults. Estimated rates of BDE-47, -99, -153 and -209 ingestion were each 2 orders of magnitude or more below the USEPA's prescribed oral reference dose values (RfDs) for typical exposure scenarios. However, exposure rates for BDE-47 and -99 reached as high as 52 and 95% of RfDs, respectively, for adults and 4.4 and 7.4%, respectively, for toddlers in high exposure scenarios. This study provides the first wide-ranging survey of NBFRs in indoor dust from homes, offices and vehicles in Australia and offers further evidence of human exposure to legacy and novel brominated flame retardants via dust ingestion.

Thyroid-disrupting chemicals and brain development: an update

This review covers recent findings on the main categories of thyroid hormone-disrupting chemicals and their effects on brain development. We draw mostly on epidemiological and experimental data published in the last decade. For each chemical class considered, we deal with not only the thyroid hormone-disrupting effects but also briefly mention the main mechanisms by which the same chemicals could modify estrogen and/or androgen signalling, thereby exacerbating adverse effects on endocrine-dependent developmental programmes. Further, we emphasize recent data showing how maternal thyroid hormone signalling during early pregnancy affects not only offspring IQ, but also neurodevelopmental disease risk. These recent findings add to established knowledge on the crucial importance of iodine and thyroid hormone for optimal brain development. We propose that prenatal exposure to mixtures of thyroid hormone-disrupting chemicals provides a plausible biological mechanism contributing to current increases in the incidence of neurodevelopmental disease and IQ loss.

Associations between serum polybrominated diphenyl ethers and thyroid hormones in a cross sectional study of a remote Alaska Native population

Polybrominated diphenyl ethers (PBDEs) are ubiquitous environmental pollutants. Arctic indigenous peoples are exposed to PBDEs through a traditional diet high in marine mammals. PBDEs disrupt thyroid homeostasis. The aim of this study was to assess the relationship between serum PBDEs and thyroid function in a remote population of St. Lawrence Island Yupik. Serum samples were collected from 85 individuals from St. Lawrence Island, Alaska and measured for concentrations of PBDEs, free and total thyroxine (T4), free and total triiodothyronine (T3), and thyroid stimulating hormone (TSH). The relationships between PBDEs and thyroid hormones were assessed using multiple linear regression fit with generalized estimating equations. Serum concentrations of several Penta-BDE congeners (BDE-28/33, 47, and 100) were positively associated with concentrations of TSH and free T3, while serum concentration of BDE-153 was negatively associated with total T3 concentrations. Both BDE-47 and 153 remained significantly associated with thyroid hormones when BDE-47, BDE-153, and BDE-209 were covariates in the same model. There were no significant relationships between serum concentrations of PBDEs and either free or total T4. Individual PBDEs are associated with thyroid hormones in serum from a remote population of Alaska Natives, and directions of effect differ by congener.

Concentrations of trace metals, phthalates, bisphenol A and flame-retardants in toys and other children's products in Israel

Trace metals and synthetic chemicals including phthalates, bisphenol A and flame retardants, are widely used in toys and childcare products, and may pose acute or chronic adverse health effects in children. In Israel, certain chemicals are regulated in childcare products, but there are still regulatory gaps. We tested regulated and unregulated contaminants in 174 item parts from 70 childcare items with potentially high oral or dermal exposure, including 22 children's jewelry items, 14 toys, 7 diaper-changing mats, 6 baby mattresses, 7 baby textiles and 14 feeding and bathing items. In children's jewelry, an unregulated product in Israel, 23% of samples exceeded the US standard for lead. In toys, a regulated product, we did not detect trace metals above the Israeli standard. In textiles, baby mattresses and diaper-changing mats, phthalates exceeded the European Union standard in 14-45% of tests with a mean of 6.74% by mass for diisononyl phthalate, and 1.32% by mass for di(2-ethylhexyl) phthalate. BPA migration exceeded the EU standard in 14-45% of tests with a mean of 1.03 ppm. The flame retardants polybrominated biphenyls, pentabromodiphenyl, octabromodiphenyl ether, tris(2,3-dibromopropyl) phosphate and tris-(aziridinyl)-phosphine oxide were not detected. For products regulated in Israel, our findings suggest general compliance with mandatory standards. However, a lack of comprehensive chemical regulation means that there are regulatory gaps, and products not regulated in Israel may contain high levels of chemical contamination, exceeding US or EU regulations. The results of this study have prompted the development of an Israeli safety standard for children's jewelry.

Childhood polybrominated diphenyl ether (PBDE) exposure and executive function in children in the HOME Study

Prenatal exposure to polybrominated diphenyl ethers (PBDEs) have been reported to impair executive function in children, but little is known whether childhood PBDE exposures play a role. Using the Health Outcomes and Measures of the Environment (HOME) Study, a prospective birth cohort in the greater Cincinnati area, we investigated the association between repeated measures of PBDEs during childhood and executive function at 8 years in 208 children and whether effect modification by child sex was present. We used child serum collected at 1, 2, 3, 5, and 8 years to measure PBDEs. The Behavior Rating Inventory of Executive Function was completed by parents to assess executive function at 8 years. We used multiple informant models to examine childhood PBDEs during several exposure windows. Null associations were observed between early childhood PBDEs and executive function. However, we observed significant adverse associations between a 10-fold increase in concurrent concentrations of BDE-28 (β=4.6, 95% CI 0.5, 8.7) and BDE-153 (β=4.8, 95% CI 0.8, 8.8) with behavioral regulation. In addition, PBDEs at 8 years were significantly associated with poorer emotional and impulse control. No associations were noted between childhood PBDEs and metacognition or global executive function. However, child sex significantly modified the associations, with significantly poorer executive function among males with higher concurrent BDE-153, and null associations in females. Our study findings suggest that concurrent PBDE exposures during childhood may be associated with poorer executive function, specifically behavior regulation. Males may also be more sensitive to adverse associations of concurrent PBDEs on executive function.

Brominated and organophosphorus flame retardants in body wipes and house dust, and an estimation of house dust hand-loadings in Dutch toddlers

Children generally have higher Flame Retardant (FR) concentrations in serum compared to other age groups. Toddler behavior enhances direct contact with house dust since their frequent presence proximate to the floor, and their mouthing behavior. This study aimed to thoroughly investigate FR levels in body wipes of toddlers 8-18 months old) and in indoor dust using a noninvasive sampling technique. In this cross-sectional study, body wipes from hands, mouth and back, and indoor household dust samples were collected in twenty-one families and analyzed for one brominated- and seven organophosphorus FRs (polybrominated diphenyl ether 209 (BDE209), tris(2-chloroisopropyl) phosphate (TCIPP), tris(chloroethyl) phosphate (TCEP), tris(1,3-dichloroisopropyl) phosphate (TDCIPP), tris(phenyl) phosphate (TPHP), tris(methylphenyl) phosphate (TMPP), resorcinol bis(diphenyl phosphate) and bisphenol A bis(diphenyl phosphate)). Accelerated solvent extraction was used for extraction and the extract was measured with liquid chromatography combined with mass spectrometry. Non-parametric correlation analyses were performed to assess associations. All FRs were detected in body- and indoor dust samples (median range: 1.0ng/hand wipe (BDE209) to 65ng/hand wipe (TCIPP)) and were mostly correlated with each other. We estimated that approximately 260mg dust (range 50-880mg) accumulated on toddler's hands per day. Hand-to-mouth frequency was negatively associated with FR levels in wipes (τ = -0.38, p = 0.04). With increasing age FR concentrations (BDE209, TCEP, TDCIPP, TPHP and TMPP) on hands decreased significantly (p = 0.01-0.03). Girls had significantly less FRs (TCEP, TCIPP, TPHP and TMPP) on the hands (p = 0.01-0.03) than boys. This is to the best of the authors' knowledge the first study in Europe that measured brominated- as well as organophosphorus FRs in several types of body wipes from toddlers and that estimated the amount of house dust that accumulates on toddler's hands.

The flame retardant DE-71 (a mixture of polybrominated diphenyl ethers) inhibits human differentiated thyroid cell function in vitro

BACKGROUND

Normal thyroid function is essential for general growth and metabolism, but can be affected by endocrine disrupting chemicals (EDCs). Polybrominated diphenyl ethers (PBDEs) have been used worldwide to reduce flammability in different materials and are suspected to be EDCs. The production of the commercial Penta- and OctaBDE mixtures is banned, but DecaBDEs and existing products may leak PBDEs into the environment. Our aim was to investigate the effect of the PentaBDE mixture DE-71 on human thyroid cells in vitro.

MATERIALS AND METHODS

Primary human thyroid cells were obtained as paraadenomatous tissue and cultured in monolayers. The influence of DE-71 on cyclic adenosine monophosphate (cAMP) and thyroglobulin (Tg) production was examined in the culture medium by competitive radioimmunoassay and enzyme-linked immunosorbent assay, respectively. Real-time quantitative PCR analysis of thyroid-specific genes was performed on the exposed cell cultures. PBDE concentrations were determined in cellular and supernatant fractions of the cultures.

RESULTS

DE-71 inhibited Tg-release from TSH-stimulated thyrocytes. At 50 mg/L DE-71, mean Tg production was reduced by 71.9% (range: 8.5-98.7%), and cAMP by 95.1% (range: 91.5-98.8%) compared to controls). Expression of mRNA encoding Tg, TPO and TSHr were significantly inhibited (p<0.0001, p = 0.0079, and p = 0.0002, respectively). The majority of DE-71 added was found in the cell fraction. No cytotoxicity was found.

CONCLUSIONS

DE-71 inhibited differentiated thyroid cell functions in a two phase response manner and a concentration-dependent inhibition of Tg and cAMP production, respectively, as well as expression of mRNA encoding Tg, TPO and TSHr. Our findings suggest an inhibiting effect of PBDEs on thyroid cells.

Predictors of Serum Polybrominated Diphenyl Ether (PBDE) Concentrations among Children Aged 1-5 Years

Serum concentrations of PBDEs were measured using gas chromatography-tandem mass spectrometry in 80 children aged 15-71 months. Demographic and behavioral data were collected on parental questionnaires; a research nurse recorded anthropometric measures and insurance status. For a subset of children (n = 17), PBDEs were measured in house dust and child handwipes sampled during a home visit. In linear and Tobit regression, log-transformed PBDE congeners were modeled as a function of child characteristics, including neighborhood-level socioeconomic indicators. BDE congeners 47, 99, and 100 were highly correlated and summed for analysis; BDE-153 was examined individually. PBDE serum concentrations were associated with socioeconomic factors; for example, a $20,000 increase in median household income in a child's ZIP code was associated with a 34% decrease (95%CI = 14-49%) in BDE-153 and a 26% decrease (95%CI = 6-42%) in ∑BDE-47,-99,-100. Lower body-mass index (BMI) z-score and household smoking were strong predictors of higher BDE-153 levels. Among children who participated in a home visit, serum PBDE was positively correlated with handwipe PBDE (Spearman r ∑BDE-47, -99, -100 = 0.48, p = 0.09), but not dust PBDE. Results indicate socioeconomic factors and BMI are strong predictors of serum PBDE levels among young children. PBDEs measured on handwipes are more predictive of serum PBDE levels than vacuum-collected dust.