Lactational Exposure to Polybrominated Diphenyl Ethers and Its Relation to Early Childhood Anthropometric Measurements

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.

Has Regulatory Action Reduced Human Exposure to Flame Retardants?

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

Associations between exposure to brominated flame retardants and metabolic syndrome and its components in U.S. adults

BACKGROUND

Humans are simultaneously exposed to numerous of environmental brominated flame retardants (BFRs). We aim to explore the overall associations of BFRs mixture on metabolic syndrome (MetS) and its components and further identify significant chemicals.

METHODS

This study included 4641 adults from the National Health and Nutrition Examination Survey (NHANES) in 2007-2016. The weighted logistic regression was conducted to estimate the association of a single BFR exposure with MetS and its components. Meanwhile, the weighted quantile sum (WQS) regression and Bayesian kernel machine regression (BKMR) were adopted to evaluate the overall associations of BFRs mixture on MetS and its components, and to identify significant chemicals. We also evaluated potential associations modified by sex.

RESULTS

In the weighted logistic regression model, PBB153 were positively associated with MetS in a dose-dependent manner (P_trend < 0.05). For its components, increasing quartiles of most BFRs were positively associated with abdominal obesity, hypertriglyceridemia, and low HDL. However, we found no statistically significant associations between BFRs and hypertension and hyperglycemia. WQS analyses found that BFRs mixture was positively associated with MetS (OR: 1.30; 95%CI:1.14, 1.46), abdominal obesity (OR: 1.15; 95%CI:1.03, 1.27), hypertriglyceridemia (OR:1.43; 95%CI:1.19, 1.67), and low HDL (OR: 1.15; 95%CI:1.01, 1.29). BKMR showed associations in a similar direction as WQS for BFRs mixture. For MetS, hypertriglyceridemia and Low HDL, PBB153, PBDE28 and PBDE209 were the most heavily weighting chemicals and had the highest the posterior inclusion probabilities in the WQS and BKMR, respectively. BFRs showed stronger associations of MetS and its components in males than in females.

CONCLUSIONS

The present study suggested exposure to BFRs mixture was positively associated with MetS and its components in adults, and PBB153, PBDE28 and PBDE209 were the significant chemicals. However, prospective cohort studies are still needed to confirm the causal effect between BFRs mixture and MetS.

Prenatal exposure to polybrominated diphenyl ethers and BMI Z-scores from 5 to 14 years

BACKGROUND

Polybrominated diphenyl ethers (PBDEs) are flame-retardant compounds widely used in household products until phase out in 2004. PBDEs are endocrine disruptors and are suggested to influence signaling related to weight control. Prenatal exposures to PBDEs may alter childhood adiposity, yet few studies have examined these associations in human populations.

METHODS

Data were collected from a birth cohort of Dominican and African American mother-child pairs from New York City recruited from 1998 to 2006. PBDE congeners BDE-47, - 99, - 100, and - 153 were measured in cord plasma (ng/μL) and dichotomized into low (< 80th percentile) and high (>80th percentile) exposure categories. Height and weight were collected at ages 5, 7, 9, 11, and an ancillary visit from 8 to 14 years (n = 289). Mixed-effects models with random intercepts for participant were used to assess associations between concentrations of individual PBDE congeners or the PBDE sum and child BMI z-scores (BMIz). To assess associations between PBDEs and the change in BMIz over time, models including interactions between PBDE categories and child age and (child age)² were fit. Quantile g-computation was used to investigate associations between BMIz and the total PBDE mixture. Models were adjusted for baseline maternal covariates: ethnicity, age, education, parity, partnership status, and receipt of public assistance, and child covariates: child sex and cord cholesterol and triglycerides.

RESULTS

The prevalence of children with obesity at age 5 was 24.2% and increased to 30% at age 11. Neither cord levels of individual PBDEs nor the total PBDE mixture were associated with overall BMIz in childhood. The changes in BMIz across childhood were not different between children with low or high PBDEs. Results were similar when adjusting for postnatal PBDE exposures.

CONCLUSIONS

Prenatal PBDE exposures were not associated with child growth trajectories in a cohort of Dominican and African American children.

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.

Hepatic oxidative stress, DNA damage and apoptosis in adult zebrafish following sub-chronic exposure to BDE-47 and BDE-153

Polybrominated diphenyl ethers (PBDEs) are ubiquitous and prolific contaminant in both the abiotic and biotic environment because of the wide industrial applications of these chemicals. In the present study, the effects of 2,2',4,4'-tetrabrominateddiphenyl ether (BDE-47) and 2,2',4,4',5,5'-hexabromodiphenyl ether (BDE-153) exposure on the induction of hepatic oxidative stress, DNA damage, and the expression of apoptosis-related genes in adult zebrafish were investigated. The activities of antioxidant enzymes, such as catalase and superoxide dimutase, significantly increased when adult zebrafish was exposed to various concentrations of BDE-47 and BDE-153 for 7 and 15 days. BDE-47 and BDE-153 elicited significant alterations in zebrafish 7-Ethoxyresorufin-O-deethylase activity at 3, 7, or 15 days of exposure. In addition, the significant increase in comet assay parameters of zebrafish hepatocytes in a concentration-dependent manner indicated BDE-47 and BDE-153 induced DNA damage, probably due to observed oxidative stress. Furthermore, a monotonically upregulation of p53 and Caspase3, which are apoptotic-regulated genes, and decreased expression ratio of the anti-apoptotic B-cell lymphoma/leukaemia-2 and Bcl2-associated X protein genes for all BDE-47 and BDE-153 treatments at 7 and 15 days indicated apoptosis induction in zebrafish liver. Our findings help elucidate the mechanisms of BDE-47- and BDE-153-induced toxicity in zebrafish hepatocytes.

Umbilical cord serum PBDE concentrations and child adiposity measures at 7 years

BACKGROUND

Polybrominated diphenyl ethers (PBDEs) exist extensively in the environment. Toxicological studies suggested PBDEs may interfere with adipogenic pathways. However, few human evidence addressed PBDE exposures in utero related to childhood adiposity.

OBJECTIVE

We assessed associations between PBDEs concentrations in cord serum and childhood adiposity measures at 7 years.

METHODS

Among 318 mother-child pairs from Sheyang Mini Birth Cohort Study (SMBCS) in China, nine PBDE congener concentrations were quantified in umbilical cord serum using gas chromatography-negative chemical ionization mass spectrometry (GC-NCI-MS). Anthropometric indicators of children aged 7 years were measured, including weight, height and waist circumference. Age and sex-specific body mass index (BMI) z scores were calculated based on World Health Organization (WHO)'s child growth standards. Multivariate linear and logistic regression models adjusted for putative confounders were performed to examine associations between PBDE congeners and adiposity parameters.

RESULTS

BDE-209 was the most abundant congener of PBDEs with a median value of 19.5 ng/g lipid. The geometric mean values of nine PBDE congeners ranged from below limit of detection (LOD) to 18.1 ng/g lipid, and the detection rates were 46.5%~96.5%. Cord serum BDE-153 and BDE-154 concentrations were associated with lower childhood BMI z score (regression coefficient, β=-0.15, 95% confidence interval: -0.29, -0.02; p=0.02; β=-0.23, 95%CI: -0.43, -0.03; p=0.03, respectively) and lower waist circumference (β=-0.75 cm, 95%CI: -1.43, -0.06; p=0.03; β=-1.22 cm, 95%CI: -2.23, -0.21; p=0.02, respectively), after controlling for potential confounders. Moreover, prenatal BDE-154 exposure was related to a decreased obesity risk of children aged 7 years (odds ratio, OR=0.46, 95%CI: 0.22, 0.94; p=0.03). These effects were only observed among boys in sex-straitified analyses.

CONCLUSIONS

Cord serum BDE-153 and BDE-154 concentrations were related to reduced adiposity measures at 7 years of age. Further evidence regarding the impacts of prenatal PBDE exposures on childhood development is warranted.

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

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

Lactational exposure of polybrominated diphenyl ethers and its association with infant developmental measurements

This study was designed to assess the effect of lactational polybrominated diphenyl ether (PBDE) exposure on early physical development of both healthy and fetal growth restriction (FGR) infants. Z scores of head circumference-for-age (ZHC), length-for-age (ZLEN), weight-for-age (ZWEI) and weight-for-length (ZWFL) were calculated according to the WHO Child Growth Standards. FGR infants had a higher PBDE exposure level and faster growth speed from 42 days to 6 months compared with healthy infants. Exposure of lower brominated BDEs (BDE28∼154) and the sum of 18 BDE congeners (BDE28∼209) negatively associated with ZHC [mean difference estimate (95 % CI): -0.71 (-1.22, -0.22) and -0.81 (-1.31, -0.33)] in FGR boys. Both BDE153 and BDE196 exposure had a significant correlation with ZLEN of boys in FGR group [mean difference estimate (95 % CI): -0.28 (-0.48, -0.07) and -0.52 (-0.91, -0.14)]. Each 10 ng/g lipid increase in the concentrations of BDE154 were respectively associated with 0.16 increase in ZWEI among boys in healthy group. No significant association was found in girls. Lactational PBDE exposure had effects on the early growth of both FGR and healthy infants. The encouragement of breastfeeding should therefore be considered in conjunction with PBDE contamination levels.

Exposure to polybrominated diphenyl ethers (PBDEs) during childhood and adiposity measures at age 8 years

BACKGROUND

Animal studies suggest polybrominated diphenyl ethers (PBDEs) may be obesogens. However, epidemiologic studies investigating childhood exposure to PBDEs and adiposity are limited, with several reporting an inverse association.

OBJECTIVES

To investigate associations between repeated childhood PBDE concentrations and adiposity measures at age 8 years.

METHODS

We examined 206 children from the Health Outcomes and Measures of the Environment Study, a birth cohort in Cincinnati, OH (2003-2006). Serum PBDEs were measured at ages 1, 2, 3, 5, and 8 years. We used multiple imputation to estimate missing PBDE concentrations. At 8 years, we measured weight, height, waist circumference, and body fat percentage. We used multiple informant models to estimate age-specific associations between PBDEs and adiposity measures.

RESULTS

We observed significant inverse associations between BDE-153 with all adiposity measures that became increasingly stronger with later childhood measurements. A 10-fold increase in BDE-153 at ages 1 and 8 years was associated with 2% (95% CI -3.9, -0.1) and 7% (95% CI -9.1, -4.7) lower body fat, respectively. No statistically significant associations were found with BDE-28, -47, -99, or -100. Child sex modified some associations; inverse associations between BDE-153 and body fat were stronger among boys, while positive and null associations were noted among girls.

CONCLUSIONS

Childhood BDE-153 concentrations were inversely associated with adiposity measures and these associations became stronger as BDE-153 measurements were more proximal to adiposity measures. Inverse associations could be attributed to reverse causality arising from greater storage of PBDEs in adipose tissue of children with higher adiposity.

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.

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.

Gestational and Lactational Exposure to an Environmentally-Relevant Mixture of Brominated Flame Retardants: Effects on Neurodevelopment and Metabolism

BACKGROUND

Developmental exposure to brominated flame retardants (BFRs), including polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecane (HBCDD), has been associated with impaired neurodevelopment and some symptoms of metabolic syndrome. However, there are inconsistencies in studies reporting neurodevelopmental effects with studies of pure substances more likely to report effects than studies of technical products. In addition, the influence of early BFR exposures on later development of metabolic disease-like symptoms has not been investigated. This study examined the effects of perinatal exposure to an environmentally relevant mixture of BFRs based on relative levels observed in house dust, on several markers of neurodevelopment and metabolism in offspring.

METHODS

Sprague-Dawley female rats were fed a diet estimated to deliver daily doses of 0, 0.06, 20, or 60 mg/kg of a mixture of PBDEs and HBCDD from before mating to weaning. Offspring were weaned to control diet and subjected to neurobehavioral and metabolic assessments.

RESULTS

Exposure to BFRs decreased vertical movement in at postnatal day (PND) 32 and increased time to emerge to a lighted area on PND 105 in offspring of both sexes. Although early life exposure to the BFR mixture did not impact measures of glucose or insulin action, male offspring had significantly decreased fat pad weights at PND 46. Total cholesterol was increased in male and female offspring exposed to the highest dose at PND 21.

CONCLUSIONS

These results suggest that gestational and lactational exposure to an environmentally relevant BFR mixture may induce changes in neurodevelopment and lipid metabolism in offspring. Birth Defects Research 109:497-512, 2017.© 2017 The Authors Birth Defects Research Published by Wiley Periodicals, Inc.