Polybrominated diphenyl ethers in cord blood and perinatal outcomes from Laizhou Wan Birth Cohort, China

Associations of cord serum polybrominated diphenyl ether (PBDE) mixture with birth outcomes and mediating role of thyroid function: Evidence from the Sheyang Mini Birth Cohort Study

BACKGROUND

Polybrominated diphenyl ethers (PBDEs), a series of worldwide applied flame retardants, may influence fetal growth and interfere with thyroid function. The study intended to explore the relationship between in-utero exposure to PBDE mixture and newborn anthropometric indexes and to further examine the potential mediating role of thyroid function.

METHODS

Demographics and laboratory measures of 924 mother-infant pairs were obtained from the database of the Sheyang Mini Birth Cohort Study. We applied gas chromatography-mass spectrometry (GC-MS) and electrochemiluminescence immunoassay to measure nine PBDE congeners and seven thyroid function parameters in umbilical cord serum samples, respectively. We fitted generalized linear models and Bayesian kernel machine regression (BKMR) to evaluate associations of lipid-adjusted cord serum PBDEs, as individuals and as a mixture, with newborn anthropometric and cord serum thyroid function parameters. We applied causal mediation analysis to test our hypothesis that thyroid function parameters act as a mediator between PBDEs and birth outcomes.

RESULTS

The molarity of cord serum ∑9PBDE had a median value of 31.23 nmol/g lipid (IQR 19.14 nmol/g lipid, 54.77 nmol/g lipid). BDE-209 was the most dominant congener. Birth length was positively associated with both single exposure to BDE-28 and cumulative exposure to PBDEs. Correspondingly, ponderal index (PI) was negatively associated with BDE-28 and the total effects of PBDE mixture. Free triiodothyronine had a negative trend with BDE-209 and PBDE mixture. In the sex-stratified analysis, BDE-153 concentrations were positively correlated with PI among males (β = 0.03; 95%CI: 0.01, 0.05; P = 0.01) but not among females. Cord serum thyrotropin mediated 14.92% of the estimated effect of BDE-153 on PI.

CONCLUSIONS

In-utero mixture exposure to PBDEs was associated with birth outcomes and thyroid function. Thyroid function might act as a mediator in the process in which PBDEs impact the growth of the fetus.

20 years of polybrominated diphenyl ethers on toxicity assessments

Polybrominated diphenyl ethers (PBDEs) serve as brominated flame retardants which continue to receive considerable attention because of their persistence, bioaccumulation, and potential toxicity. Although PBDEs have been restricted and phased out, large amounts of commercial products containing PBDEs are still in use and discarded annually. Consequently, PBDEs added to products can be released into our surrounding environments, particularly in aquatic systems, thus posing great risks to human health. Many studies and reviews have described the possible toxic effects of PBDEs, while few studies have comprehensively summarized and analyzed the global trends of their toxicity assessment. Therefore, this study utilizes bibliometrics to evaluate the worldwide scientific output of PBDE toxicity and analyze the hotspots and future trends of this field. Firstly, the basic information including the most contributing countries/institutions, journals, co-citations, influential authors, and keywords involved in PBDE toxicity assessment will be visualized. Subsequently, the potential toxicity of PBDE exposure to diverse systems, such as endocrine, reproductive, neural, and gastrointestinal tract systems, and related toxic mechanisms will be discussed. Finally, we conclude this review by outlining the current challenges and future perspectives in environmentally relevant PBDE exposure, potential carriers for PBDE transport, the fate of PBDEs in the environment and human bodies, advanced stem cell-derived organoid models for toxicity assessment, and promising omics technologies for obtaining toxic mechanisms. This review is expected to offer systematical insights into PBDE toxicity assessments and facilitate the development of PBDE-based research.

Polybrominated diphenyl ether (PBDE) exposure and adverse maternal and infant health outcomes: Systematic review

Polybrominated diphenyl ethers (PBDEs) are flame retardants found in ambient environment and are measured in humans. There are reports on general PBDE toxicity, including endocrine disrupting properties. Studies on adverse maternal and infant outcomes and underlying toxicity mechanisms needs to be understood. The objective of this study was to conduct a systematic review to examine the state of science on the relationship between PBDE and adverse maternal/infant health outcomes and related maternal biomarker changes. This literature review was conducted using PubMed, Scopus, Embase and Web of Science for published articles from January 2005-February 2022. Article quality was assessed using Newcastle-Ottawa Scale. Of the 1518 articles, only 54 human observational studies were screened in for this review. A second reviewer examined the validity of these articles. Reports on associations between PBDE and maternal health outcomes included gestational hypertension/preeclampsia (N = 2) and gestational diabetes mellitus/glycemic index (N = 6). Meanwhile, reports on PBDE and infant outcomes (N=32) included effects on infant birth weight, birth length and cephalic perimeter, preterm birth, fetal growth restriction and APGAR scores. Although findings on PBDE exposure and adverse infant outcomes showed inconsistencies across studies, in general, negative correlations between maternal PBDEs and infant birth weight, birth length and cephalic perimeter were seen, in few cases, after stratification by sex. Association between maternal PBDE and maternal biomarkers (N=18) suggested negative impact of PBDE exposure on markers relevant to neuro-endocrine system and inflammatory processes. The review findings identified potential associations between maternal PBDE and adverse maternal/infant health outcomes. Furthermore, PBDE-related biomarker changes suggest disturbances in maternal mechanisms relevant to endocrine disrupting properties of PBDEs. The observed study heterogeneity can be attributed to factors namely, sample size, study design and statistical analysis. Overall review findings imply the necessity for further research to validate PBDE exposure-related adverse maternal/infant health effects and to validate underlying toxicity mechanisms.

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.

MiR-24-3p/Dio3 axis is essential for BDE47 to induce local thyroid hormone disorder and neurotoxicity

BDE47 (2,2,4,4-tetrabromodiphenyl ether) is a member of the most important congeners of polybrominated diphenyl ethers (PBDEs) and has been identified as a developmental, reproductive and nervous system toxicant and endocrine system disruptor due to its frequent detection in human tissue and environmental samples. Our preliminary work suggested that high- and low-level of bromodiphenyl ethers have different effects on neuronal cells with differential targets of actions on neural tissues. In this study, we presented the underlying mechanism of BDE47 neurotoxicity from the perspective of thyroid hormone (TH) metabolism using in vitro model of human SK-N-AS neuronal cells. BDE47 could induce local TH metabolism disorder in neuronal cells by inhibiting the expression of the main enzyme, human type III iodothyronine deiodinase (Dio3). Further elucidation revealed that BDE47 effectively up-regulating miR-24-3p, which binds to the 3'-UTR of Dio3 and inhibits its expression. In addition, BDE47 could also inhibit the deiodinase activity of Dio3. Collectively, our study demonstrates the molecular mechanism of BDE47 regulating Dio3-induced TH metabolism disorder through inducing miR-24-3p, providing new clues for the role of miRNAs in neurodevelopmental toxicity mediated by environmental pollutants.

Serum polybrominated diphenyl ether exposure and influence factors in blood donors of Wuxi adults from 2013 to 2016

Polybrominated diphenyl ethers (PBDEs) have been used as brominated flame retardants worldwide and are correlated with extensive environmental pollution and human health concerns. This study is aimed at analyzing the concentrations of PBDEs and at evaluating their temporal trends among a population of blood donors (n = 33) over a 4-year period. A total of 132 serum samples were used for PBDE detection. Nine PBDE congeners were quantified in serum samples by gas chromatography with mass spectrometry (GC-MS). The median concentrations of Σ₉PBDEs in each year were 33.46, 29.75, 30.85, and 35.02 ng/g lipid, respectively. Most of the PBDE congeners showed a downward trend from 2013 to 2014 and then increased after 2014. No correlations between age and PBDE congener concentrations were observed, while concentrations of each congener and Σ₉PBDE were nearly always lower in females than in males, especially in BDE-66, BDE-153, BDE-183, BDE-190, and Σ₉PBDE. We also found that the intake of fish, fruit, and eggs in the daily diet was related to the exposure level of PBDEs. Our results suggest that, as deca-BDE is still produced and used in China, diet is an important exposure pathway for PBDEs, and follow-up studies will be required to improve our understanding of the behaviors of PBDE isomers in humans and the exposure levels.

Prenatal exposure to polybrominated diphenyl ethers and birth outcomes

BACKGROUND

Polybrominated diphenyl ethers (PBDEs) were used as flame retardants and from their end-use products they can be released to accumulate within indoor environments. This may result in exposures to pregnant women with potential adverse effects on the developing fetus. While studies have shown associations between prenatal PBDE exposure and poor birth outcomes, research has mainly focused on birth weight and gestational age and may miss important indicators of newborn size.

METHODS

The sample included a cohort of Dominican and African American mother-child pairs from New York City recruited from 1998 to 2006. PBDE congeners (BDE-47, BDE-99, BDE-100, and BDE-153) were measured in cord serum at birth and dichotomized into low (<80th percentile) and high (>80th percentile) categories. Weight, length, head circumference, and gestational age were measured at birth and the ponderal index (birth weight/length x 100), size for gestational age, and population-based z-scores were calculated (n = 305). Separate regression analyses were conducted to estimate associations between PBDEs or PBDE sum (ng/g lipid) and birth outcomes. Quantile g-computation was performed to estimate the effect of total PBDE mixture. We also assessed effect modification by sex and ethnicity.

RESULTS

Adjusting for relevant covariates, the high exposure category of BDE-153 was associated with lower birth weight z-score (-0.25, 95% CI: -0.5, 0.0) and longer gestation (0.43 weeks, 95% CI: 0.07, 0.79). The high exposure category of BDE-99 was associated with lower birth length z-score (-0.55, 95% CI: -0.98, -0.12). There was a negative association between the overall PBDE mixture and birth length z-score (-0.10, 95% CI: -0.21, 0.00) per 1 quintile increase in PBDEs. There was no effect modification by sex or ethnicity.

CONCLUSIONS

These results suggest that prenatal exposures to BDE-153, BDE-99, and total PBDE mixture are associated with birth outcomes in a cohort of Dominican and African American newborns.

2, 2', 4, 4'-tetrabromodiphenyl ether induces placental toxicity via activation of p38 MAPK signaling pathway in vivo and in vitro

2, 2', 4, 4'-tetrabromodiphenyl ether (BDE-47) is one of the most important polybrominated diphenyl ethers (PBDEs) congeners, and epidemiological studies have shown that it can cause adverse pregnancy outcomes. The aim of our study was to investigate the role of placental injury in BDE-47-induced adverse pregnancy outcomes through in vivo and in vitro models. From day 0.5 to day 16.5 of pregnancy of ICR mice, BDE-47 oral doses of 0, 25, 50 and 100 mg/kg/day were administered. Immunohistochemical staining found that BDE-47 inhibited the expression of CD34 in mouse placenta, and ELISA results showed that BDE-47 reduced the levels of VEGF and PlGF in the serum of pregnant mice. Western blot assays found that the expression levels of VEGF-A and invasion-related factors were decreased in the placentas of BDE-47-treated group, which indicated that BDE-47 could impair placental angiogenesis. Furthermore, BDE-47 inhibited proliferation, increased apoptosis and autophagy, and activated p38 MAPK signaling pathway in mouse placental tissue. In vitro, HTR-8/SVneo cells were treated with 0, 5, 10, 20 μM BDE-47 for 24 h. Wound healing assays and Transwell assays showed that BDE-47 inhibited the migration and invasion ability of HTR-8/SVneo cells. We also found that BDE-47 inhibited the proliferation of HTR-8/SVneo cells and increased apoptosis and autophagy. BDE-47 activated p38 MAPK signaling pathway in HTR-8/SVneo cells, and inhibition of p38 MAPK signaling pathway in HTR-8/SVneo cells restored the effects caused by BDE-47. In conclusion, BDE-47 impairs placental angiogenesis by inhibiting cell migration and invasion, and induces placental toxicity by inhibiting proliferation, increasing apoptosis and autophagy. In vitro, activation of p38 MAPK signaling pathway is involved in the processes of placental injury by BDE-47.

Associations between prenatal exposure to polybrominated diphenyl ethers and physical growth in a seven year cohort study

Although evidence suggests that prenatal exposure to polybrominated diphenyl ethers (PBDEs) alter offspring's physical growth, most studies rely upon physical growth at a single timepoint, and little is known regarding their longitudinal effects over time. In the current study, we determined the associations between prenatal PBDEs exposure and child physical growth by following up 207 mother-child pairs from the Laizhou Wan Birth Cohort (LWBC) from pregnancy until the children were seven years old. Child physical growth including weight, height, and body mass index (BMI) was assessed at birth, and at one, two and seven years of age. Prenatal exposure to PBDEs was quantified by measuring eight PBDE congeners (BDE-28, BDE-47, BDE-85, BDE-99, BDE-100, BDE-153, BDE-154, and BDE-183) in maternal serum samples collected upon hospital admission for delivery. Linear mixed models were applied to examine the associations between prenatal PBDEs exposure and repeated measures of child physical growth, and to determine whether these associations were modified by child's sex. Our findings indicated that BDE-28, BDE-85, BDE-153, BDE-183, and Σ₇PBDEs were positively associated with child weight z-score; and that BDE-28, BDE-47, BDE-85, BDE-99, BDE-153, and Σ₇PBDEs were positively associated with child height z-score. In addition, these associations were modified by the child's sex as reflected by pronounced positive associations among boys, while negative associations were noted among girls. In conclusion, our findings indicated the sex-specific associations between prenatal PBDE exposures and child physical growth during the first seven years of life.

Effects of Polybrominated Diphenyl Ethers on Hormonal and Reproductive Health in E-Waste-Exposed Population: A Systematic Review

Electronic waste management is a global rising concern that is primarily being handled by informal recycling practices. These release a mix of potentially hazardous chemicals, which is an important public health concern. These chemicals include polybrominated diphenyl ethers (PBDEs), used as flame retardants in electronic parts, which are persistent in nature and show bioaccumulative characteristics. Although PBDEs are suspected endocrine disruptors, particularly targeting thyroid and reproductive hormone functions, the relationship of PBDEs with these health effects are not well established. We used the Navigation Guide methodology to conduct a systematic review of studies in populations exposed to e-waste to better understand the relationships of these persistent flame retardants with hormonal and reproductive health. We assessed nineteen studies that fit our pre-determined inclusion criteria for risk of bias, indirectness, inconsistency, imprecision, and other criteria that helped rate the overall evidence for its quality and strength of evidence. The studies suggest PBDEs may have an adverse effect on thyroid hormones, reproductive hormones, semen quality, and neonatal health. However, more research is required to establish a relationship of these effects in the e-waste-exposed population. We identified the limitations of the data available and made recommendations for future scientific work.

Associations Between Polybrominated Diphenyl Ethers Concentrations in Human Placenta and Small for Gestational Age in Southwest China

BACKGROUND

Prenatal exposures to polybrominated diphenyl ethers (PBDEs) may affect fetal growth. Small for gestational age (SGA) is a measure based on birth weight and gestational age at birth and represents a good indicator of fetal growth but it has been used only in a small number of studies. The present study aimed to examine the associations between PBDEs exposure and the risk of SGA among participants from a birth cohort in Southwest China.

METHODS

The concentrations of eight common PBDE congeners (BDE-28, BDE47, BDE-99, BDE-100, BDE-153, BDE-154, BDE-183, and BDE-209) in 996 human placental samples collected between May to October 2020 were determined. A questionnaire survey was administered regarding maternal characteristics. The outcome data of the newborns were obtained from the medical record. The Mann-Whitney U test and binomial logistic regression analysis were used to assess associations between PBDEs concentrations (as a continuous or categorical variable) and SGA.

RESULTS

All PBDE congeners were detected in more than 73% of samples. The median concentrations of ΣPBDEs were 10.08 ng/g lipid weight (lw). BDE-209 was the most abundant PBDE congener, contributed 28% to ΣPBDEs. There were 114 (11.4%) SGA infants. The levels of BDE-99, BDE-100, BDE-209, and the total levels of ΣPBDEs in the SGA group were significantly higher than those in the controls. When classifying the PBDEs concentrations as two categories: low and high, high level of ΣPBDEs was associated with increased risk of SGA [odds ratio (OR): 2.203, 95% confidence interval (CI): 1.453-3.340] after adjusting for potential covariates. The association remained significant when stratifying the data by gender of the newborn (OR: 2.572, 95% CI: 1.337-4.947 for boys; OR: 2.385, 95% CI: 1.315-4.325 for girls).

CONCLUSION

The present study adds to the literature by using placenta to measure PBDEs exposure during pregnancy, and provides evidence that prenatal exposure to PBDEs may be associated with the risk of SGA, at least at the levels of exposure in our population.

Polybrominated diphenyl ether congener 99 (PBDE 99) promotes adipocyte lineage commitment of C3H10T1/2 mesenchymal stem cells

Obesogens are defined as chemicals that trigger obesity partially by stimulating adipogenesis. Adipogenesis consists of two successive processes: the adipocyte lineage commitment of pluripotent stem cells and the differentiation of preadipocytes. Compared with the differentiation of preadipocytes, the effects of most environmental obesogens on adipocyte lineage commitment remain largely unknown. In this study, investigations are performed to explore the influences of PBDE 99 on the adipocyte lineage commitment based on C3H10T1/2, which has been widely used as a mesenchymal stem cell (MSC) model. Our results indicated that exposure to PBDE 99 during commitment stage resulted in significant up-regulation of subsequent adipogenesis in C3H10T1/2 MSCs. Interestingly, PBDE 99 did not affect the osteogenesis of C3H10T1/2 MSCs, although the adipogenesis and osteogenesis of MSCs are typically reciprocal. PBDE 99 was further demonstrated to significantly decrease the expression of Pref1, the marker of very early adipose mesenchymal precursor, and its downstream effector, Sox9. This result strongly suggested that PBDE 99 facilitated adipocyte commitment to exert adipogenic effect on C3H10T1/2 MSCs. Mechanistic studies revealed that PBDE 99 efficiently inhibited Hedgehog signaling transduction, a conserved negative regulator of the adipocyte lineage commitment. Furthermore, the effects of PBDE 99 on adipogenesis were abrogated by the co-treatment with SAG, a specific Hedgehog signaling activator, suggesting inhibition of Hedgehog signaling is responsible for the effect of PBDE 99 on adipocyte commitment. Taking together, these results strongly suggested enhanced adipocyte lineage commitment was involved in potential obesogenic effect of PBDE 99, presumably through repressing Hedgehog signalling during commitment stage. Moreover, the results of this study indicated that C3H10T1/2 can be used as a feasible MSCs cell model to evaluate the capabilities of potential obesogens on adipocyte commitment.

Prenatal exposure to environmentally relevant levels of PBDE-99 leads to testicular dysgenesis with steroidogenesis disorders

Polybrominated diphenyl ethers (PBDEs) are a widely used class of brominated flame retardants. Exposure to PBDEs could induce testicular damage in mammals, but the effects and potential mechanism of action of prenatal exposure to environmentally relevant PBDEs on testicular development remain unclear. For the in vivo study, pregnant ICR mice were exposed to environmentally relevant levels of 2,2',4,4',5-pentabromodiphenyl ether (PBDE-99), a major component of commercial PBDE mixtures. We found that the anogenital index and testicular organ coefficient were significantly decreased, the incidence of cryptorchidism was increased, and testicular histology was disturbed in male offspring. Transcriptomic profiling showed that steroidogenesis disorders were significant in all PBDE-99 exposure groups. The testosterone levels, expressions of testosterone regulators, and the number of CYP11A1-positive and 11β-HSD1-positive Leydig cells were significantly decreased after PBDE-99 exposure. For the in vitro study, TM3 Leydig cells were exposed to PBDE-99 at gradient concentrations. Transcriptomic profiling and validation experiments showed that PBDE-99 upregulated reactive oxygen species, activated the ERK1/2 pathway, inhibited the ubiquitination degradation pathway, and finally induced Leydig cell apoptosis. Cumulatively, these findings revealed that prenatal exposure to environmentally relevant levels of PBDE-99 leads to steroidogenesis disorders by inducing the apoptosis of Leydig cells, causing testicular dysgenesis.

DNA methylation changes induced by BDE-209 are related to DNA damage response and germ cell development in GC-2spd

Decabrominated diphenyl ether (BDE-209) is generally utilized in multiple polymer materials as common brominated flame retardant. BDE-209 has been listed as persistent organic pollutants (POPs), which was considered to be reproductive toxin in the environment. But it still remains unclear about the effects of BDE-209 on DNA methylation and the induced-male reproductive toxicity. Due to the extensive epigenetic regulation in germ line development, we hypothesize that BDE-209 exposure impacts the statue of DNA methylation in spermatocytes in vitro. Therefore, the mouse GC-2spd (GC-2) cells were used for the genome wide DNA methylation analysis after treated with 32 μg/mL BDE-209 for 24 hr. The results showed that BDE-209 caused genomic methylation changes with 32,083 differentially methylated CpGs in GC-2 cells, including 16,164 (50.38%) hypermethylated and 15,919 (49.62%) hypomethylated sites. With integrated analysis of DNA methylation data and functional enrichment, we found that BDE-209 might affect the functional transcription in cell growth and sperm development by differential gene methylation. qRT-PCR validation demonstrated the involvement of p53-dependent DNA damage response in the GC-2 cells after BDE-209 exposure. In general, our findings indicated that BDE-209-induced genome wide methylation changes could be interrelated with reproductive dysfunction. This study might provide new insights into the mechanisms of male reproductive toxicity under the environmental exposure to BDE-209.

Women with high plasma levels of PBDE-47 are at increased risk of preterm birth

OBJECTIVES

Nearly 100% of North American women have detectable levels of flame retardants such as polybrominated diphenyl ethers (PBDEs) in their plasma. These molecules have structural homology to thyroid hormones and may function as endocrine disruptors. Thyroid dysfunction has previously been associated with increased risk for preterm birth. Therefore, we conducted a multi-center, case-cohort study to evaluate if high plasma concentrations of a common PBDE congener in the first trimester increases the risk of preterm birth and its subtypes.

METHODS

Pregnant women were recruited at the onset of initiation of prenatal care at Kaiser-Permanente Southern California (KPSC)-West Los Angeles and KPSC-San Diego medical centers. Plasma samples from women whose pregnancies ended preterm and random subset of those delivering at term were assayed for PBDE-47 and thyroid-stimulating hormone (TSH) by immunoassay. Quartile cutoffs were calculated for the patients at term and used to determine if women with exposures in the 4th quartile are at increased risk for preterm birth using logistic regression.

RESULTS

We found that high concentrations of PBDE-47 in the first trimester significantly increased the odds of both indicated (adjusted odds ratio, adjOR=2.35, 95% confidence interval [CI]: 1.31, 4.21) and spontaneous (adjOR=1.76, 95% CI: 1.02, 3.03) preterm birth. Regardless of pregnancy outcome, TSH concentrations did not differ between women with high and low concentrations of PBDE-47.

CONCLUSIONS

These results suggest that high plasma concentrations of PBDE-47 in the first trimester, increases the risk of indicated and spontaneous preterm birth.

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.

Effects of prenatal exposure to polybrominated diphenyl ethers (PBDEs) on the second to fourth digit ratio in children aged 4 years

BACKGROUND

The second to fourth digit ratio (2D:4D) is assumed to be a biomarker of prenatal sex steroid exposure, correlating negatively with prenatal testosterone and positively with prenatal estrogen. The ratio has been suggested to be influenced by endocrine disrupting chemicals (EDCs). However, evidence regarding effects of prenatal exposure to polybrominated diphenyl ethers (PBDEs) on 2D:4D of children was sparse.

OBJECTIVES

We investigated the associations between prenatal exposure to PBDEs and 2D:4D of children aged 4 years.

METHODS

Participants were mother-child pairs from the Shanghai-Minhang Birth Cohort Study (S-MBCS) which enrolled pregnant women at 12-16 weeks of gestation from April to December 2012. Nine PBDE congeners in venous umbilical cord plasma of 340 children were measured. Digit lengths were measured using a vernier caliper in children aged 4 years and 2D:4D for left and right hands and average 2D:4D value of both hands were calculated. A total of 281 children (160 boys and 121 girls) who had data on both 2D:4D and PBDE concentrations were included in the final analysis. Associations between prenatal PBDE exposures and 2D:4D were investigated using multiple linear regression models.

RESULTS

Among the nine congeners, BDE-47 had the highest detection rate of 86.12% with the highest median concentration of 0.20 ng/ml lipid. Five PBDE congeners with detection rates greater than or close to 50% (BDE-28, -47, -99, -100 and -153) and Σ₅PBDEs (the sum of them) were included in final analysis. For girls, a consistent pattern for the positive associations between prenatal PBDE exposures and 2D:4D of children was observed mainly for the left hand, where those in the highest exposure groups had higher 2D:4D compared to the lowest exposure groups (a feminizing effect), with statistically significant associations observed for BDE-47 (β = 0.0247, 95% confidence interval (CI): 0.0017, 0.0477), -100 (β = 0.0264, 95% CI: 0.0087, 0.0441) and Σ₅PBDEs (β = 0.0201, 95% CI: 0.0027, 0.0374). For boys, compared with the lowest exposure groups, statistically significantly higher (feminized) 2D:4D for both hands was observed in those with the highest exposure levels of BDE-100 (β = 0.0147, 95% CI: 0.0005, 0.0289 for the left hand; β = 0.0182, 95% CI: 0.0046, 0.0318 for the right hand) and those with the middle and the highest exposure levels of BDE-153 (middle vs. undetected, β = 0.0215, 95% CI: 0.0072, 0.0358 for the left hand; β = 0.0155, 95% CI: 0.0015, 0.0295 for the right hand; highest vs. undetected, β = 0.0162, 95% CI: 0.0017, 0.0307 for the left hand; β = 0.0152, 95% CI: 0.0011, 0.0294 for the right hand).

CONCLUSIONS

Our study provides preliminary evidence that prenatal exposure to PBDEs might be associated with higher 2D:4D in boys and girls.

Association between fetal growth restriction and maternal exposure to polybrominated diphenyl ethers

Humans are exposed to polybrominated diphenyl ethers (PBDEs) via ingestion of food, dust inhalation, and dermal absorption. Exposure to PBDEs via the placenta and breast milk is a special and important pathway in infants. This nested case-control study aimed to investigate the levels of PBDEs in maternal serum and colostrum, and to assess the association between the occurrence of fetal growth restriction (FGR) and prenatal exposure to PBDEs. We recruited 293 mother-newborn pairs, including 98 FGR cases and 195 healthy controls in Wenzhou, China. Maternal serum and colostrum samples were collected during pregnancy and after delivery, respectively, and the levels of PBDEs were measured by gas chromatography-tandem mass spectrometry. The total levels of PBDEs in maternal serum and colostrum were found to be in equilibrium, but congener profiles of PBDEs in these matrices were different. Increased BDE-207, BDE-209, ∑BDE196-209 and ∑PBDEs levels in maternal serum and BDE-99, ∑BDE17-154 and ∑PBDEs levels in colostrum were correlated with decreased birth weight Z score. Increased concentrations of higher brominated BDEs in maternal serum (odds ratio (OR) = 1.010, 95%CI = 1.003-1.018) and low-to moderately brominated BDEs in colostrum (OR = 1.004, 95%CI = 1.000-1.009) were associated with increased risk of FGR, which showed an exposure-response relationship. In addition, infants with FGR were more exposed to PBDEs in colostrum after birth than healthy infants. Longitudinal birth cohort studies are needed to determine the prolonged effect of PBDEs exposure on the growth of FGR infants in the future.

Associations between in utero exposure to polybrominated diphenyl ethers, pathophysiological state of fetal growth and placental DNA methylation changes

BACKGROUND

Polybrominated diphenyl ethers (PBDEs) are environmental chemicals with harmful effects on pregnancy, but their effects on adverse developmental outcomes are not fully understood. The placental DNA methylation is strongly influenced by prenatal environmental factors and has been linked to fetal growth.

OBJECTIVE

To evaluate the association between in utero PBDEs exposure, placental DNA methylation changes (growth regulatory genes), and pathophysiology of fetal growth (birth outcomes, fetal growth retardation) in a population-based pregnancy cohort study.

METHODS

This was a nested case-control study within the prospective Wenzhou Birth Cohort including 130 fetal growth retardation (FGR) cases and 130 healthy controls and their mothers recruited from June 2016 to June 2017. FGR was diagnosed based on the comprehensive evaluation of ultrasound results at 24, 28, and 32 weeks of gestation. Neonatal birth measurements were obtained from medical records. Gestational exposure to 19 PBDEs, including 13 lower BDE congeners (BDE-17-190) and 6 higher brominated BDE congeners (BDE-196-209), were determined by gas chromatography tandem mass spectrometry in the umbilical cord blood. Placental DNA methylation changes of one repetitive element (LINE1) and two candidate genes (HSD11B2, IGF2) were characterized by quantitative polymerase chain reaction-pyrosequencing. Multiple linear regression and logistic regression models were used to examine the associations among PBDEs exposure, fetal growth indicators, and DMR (differential methylation region) methylation fractions. Sobel tests were conducted to assess DNA methylation as a mediator in multivariate models.

RESULTS

After excluding women who withdrew from the study or were lost to follow-up or failed to provide placenta or umbilical cord blood, 249 mother-newborn pairs (124 FGR cases, 125 controls) were included in the final analysis. Elevated BDE-206 (OR: 1.569, 95% CIs: 1.053-2.338), BDE-17-190 (OR: 2.860, 95% CIs: 1.233-6.634), BDE-196-209 (OR: 1.688, 95% CIs: 1.024-2.783) and ∑₁₉PBDEs (OR: 2.387, 95% CIs: 1.220-4.668) concentrations were associated with increased risk of FGR in newborns. FGR birth was also associated with increased DNA methylation of HSD11B2 (OR: 1.145, 95% CIs: 1.032-1.270) and decreased DNA methylation of IGF2 (OR: 0.892, 95% CIs: 0.845-0.941). In addition, BDE-17-190 showed significant associations with DNA methylation of HSD11B2 and IGF2 (β: 1.127, 95% CIs: 0.069-2.186; β: -3.452, 95% CIs: -5.512-1.392), indicating placental DNA methylation changes of HSD11B2 and IGF2 were related to both lower BDE congeners exposure and fetal growth. Further mediation analyses showed that IGF2 methylation mediated about 40% of the effects of BDE-17-190 in umbilical cord blood on neonatal FGR.

CONCLUSION

We report an inverse association between in utero exposures to PBDEs and fetal growth and provide evidence supporting epigenetic gene plasticity in these associations. Changes in placental DNA methylation might be part of the underlying biological pathway between prenatal PBDEs exposure and adverse fetal growth.

Multicenter biomonitoring of polybrominated diphenyl ethers (PBDEs) in colostrum from China: Body burden profile and risk assessment

Polybrominated diphenyl ethers (PBDEs) were listed in the Stockholm Convention due to their persistent and toxic nature. In utero exposure to PBDEs might affect fetal development as it is sensitive when exposed to even low dose of xenobiotic substances during the pregnancy. In this study, a multi-centre human biomonitoring study of tri-to hexa-BDEs was conducted in three Chinese cities using 60 colostrum samples from local residents. The patterns and influencing factors, correlation with the birth outcome, and potential health risks during the breastfeeding of tri-to hexa-BDEs in the colostrum samples were assessed. The median concentration of tri-to hexa-BDEs was 9.1 (Interquartile range: 3.1-19.5) ng g^-1 lipid weight, and BDE-153 contributed 68% of the detected PBDEs. The PBDE levels were mostly associated with maternal age and drinking water sources, while correlations with other factors including weight gain, BMI, parity and the number of aborted pregnancies was not significant. The level of BDE-28 was positively correlated with the birth weight, while the BDE-99 was positively correlated with the head circumference, using multilinear regression. For the total hazard quotients, 60% of the infants have an estimated value higher than 1, showed potential chronic hazard for future development and possible adverse health effects to the babies from the exposure to PBDE congeners. Alternative food source seems to have a lower risk for neonates than the colostrum, but the advantages of breastfeeding undoubtedly outweigh the risks and potential adverse health effects caused by environmental PBDEs and other xenobiotic chemical exposure.

Epigenetic response profiles into environmental epigenotoxicant screening and health risk assessment: A critical review

The epigenome may be an important interface between exposure to environmental contaminants and adverse outcome on human health. Many environmental pollutants deregulate gene expression and promote diseases by modulating the epigenome. Adverse epigenetic responses have been widely used for risk assessment of chemical substances. Various pollutants, including trace elements and persistent organic pollutants, have been detected frequently in the environment. Epigenetic toxicity of environmental matrices including water, air, soil, and food cannot be ignored. This review provides a comprehensive overview of epigenetic effects of pollutants and environmental matrices. We start with an overview of the mechanisms of epigenetic regulation and the effects of several types of environmental pollutants (trace elements, persistent organic pollutants, endocrine disrupting chemicals, and volatile organic pollutants) on epigenetic modulation. We then discuss the epigenetic responses to environmental water, air, and soil based on in vivo and in vitro assays. Finally, we discuss recommendations to promote the incorporation of epigenotoxicity into contamination screening and health risk assessment.

Health Risks of Polybrominated Diphenyl Ethers (PBDEs) and Metals at Informal Electronic Waste Recycling Sites

Concerns about the adverse public health consequences of informal electronic waste (e-waste) recycling are increasing. This study adopted a cross-sectional study design to gain insights into health risks (cancer and non-cancer risks) associated with exposure to e-waste chemicals among informal e-waste workers via three main routes: Dermal contact, ingestion, and inhalation. The e-waste chemicals (PBDE and metals) were measured in the dust and top soils at e-waste sites (burning, dismantling, and repair sites). Adverse health risks were calculated using the EPA model developed by the Environmental Protection Agency of the United States. The concentrations of the e-waste chemicals and the health risks at the e-waste sites increased as the intensity of the e-waste recycling activities increased: control sites < repair sites < dismantling sites < burning sites. Dermal contact was the main route of exposure while exposure via inhalation was negligible for both carcinogenic and non-carcinogenic risks. Cumulative health risks via all routes of exposure (inhalation, ingestion, and dermal contact) exceeded the acceptable limits of both non-cancer effects and cancer risk at all e-waste sites. This indicates that overall the e-waste workers are at the risk of adverse health effects. Therefore, the importance of occupational safety programs and management regulations for e-waste workers cannot be over emphasised.

Prenatal polybrominated diphenyl ethers exposure and anogenital distance in boys from a Shanghai birth cohort

BACKGROUND

Polybrominated diphenyl ethers (PBDEs) are major brominated flame retardant (BFR) chemicals with endocrine-disrupting properties. One small-scale study on humans has suggested that prenatal exposure to PBDEs is adversely related to anogenital distance (AGD) a sensitive marker for prenatal androgen exposure. The aim of the present study was to examine the associations between prenatal exposure to PBDEs and AGD among boys 0-4 years of age in a cohort study.

METHODS

In the Shanghai-Minhang Birth Cohort Study (S-MBCS), nine PBDE congeners were measured in cord plasma of 192 male infants. We measured anopenile distance (AGD_AP) and anoscrotal distance (AGD_AS) at birth, 6 months, 12 months, and 48 months of age. A total of 190 boys with neonatal concentrations of PBDEs (ng/g lipid) who had at-least one AGD measurement were included in our study. Information on potential confounding variables were collected through in-person interviews. Multiple linear regression models and generalized estimating equation (GEE) models were used to evaluate the associations between prenatal PBDEs concentrations and AGD.

RESULTS

Among the nine congeners, BDE-47 had the highest detection rate (83.68%) and the highest median concentration (0.18 ng/g lipid). Boys who had neonatal concentration of BDE-47 or Σ₄PBDEs (sum of BDE-47, BDE-99, BDE-100, and BDE-153) in the higher quartile generally had shorter AGD_AP and AGD_AS than those in the first quartile. Significant inverse associations were found between AGD_AS and fourth quartile BDE-47 levels among boys 12 months and 48 months of age (β = -5.57, 95% confidence interval (CI): -9.89, -1.25 for 12 month of age; β = -4.32, 95% CI: -8.18, -0.46 for 48 month of age). Inverse associations were also observed between AGD_AS and fourth quartile Σ₄PBDEs levels among boys 12 months of age (β = -5.13, 95% CI: -9.89, -1.25). In GEE models, similar patterns of association were also observed between BDE-47 and AGD_AS.

CONCLUSIONS

Our findings provide preliminary evidence that prenatal exposure to BDE-47 and Σ₄PBDEs, even at low environmental levels, may be associated with shorter AGD in boys. This data suggest that prenatal exposure to PBDEs may have adverse effects on male reproductive development. Further studies should be conducted to validate these results.