Serum concentrations of polybrominated biphenyls (PBBs), polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) in the Michigan PBB Registry 40 years after the PBB contamination incident

Current exposure to environmental pollutants in the general adult population of Kinshasa, Democratic Republic of Congo (DRC): A cross-sectional study

BACKGROUND

Environmental pollution is a serious public health problem because of its adverse effects on both human health and biodiversity. In Western countries, many human biomonitoring (HBM) studies are conducted to assess population exposure to pollutants. In contrast, the number of HBM studies in Africa is very low.

OBJECTIVE

To measure contamination by arsenic, lead, 4,4'-dichlorodiphenyldichloroethylene (4,4'-DDE) and polychlorobiphenyls (PCBs) in the adult population of Kinshasa and to identify the susceptible population.

METHODS

In the present work, we measured the contamination by arsenic in urine and lead in blood and by 4,4'-DDE and polychlorobiphenyls (PCBs) in serum in samples collected from 151 volunteers recruited in Kinshasa, the capital of the Democratic Republic of Congo (DRC).

RESULTS

The PCBs 180, -153 and -138 were detected in most samples with median concentrations of 0.04, 0.05 and 0.04 ng/ml, respectively. The median concentration of 4,4'-DDE was 0.83 ng/ml and 12.7% of our population showed contamination above the threshold of 3.675 ng/ml, which is associated with a significantly higher risk of cancer. Arsenic concentrations were also high (median: 48.1 μg/L in urine). Finally, exposure to lead is problematic: the median blood concentration was 54.9 μg/L, which is above the thresholds proposed by the WHO and the US CDC (50 μg/L and 35 μg/L respectively) to initiate clinical intervention, and 12.6% of the population had a lead level above 100 μg/L, which is associated with several health outcomes.

CONCLUSIONS

Our results highlight the need for further HBM studies in Africa and should encourage the authorities of the DRC to implement laws and regulations to reduce pollution and population exposure.

Mechanism and kinetics of thermal decomposition of decabromobiphenyl: Reaction with reactive radicals and formation chemistry of polybrominated dibenzofurans

Although the production and usage of polybrominated biphenyls (PBBs) as brominated flame retardants have already been prohibited, they still pose a threat to the environment and human health. However, the evolutionary behaviors and decomposition mechanisms of PBBs during thermal treatment of waste remain unclear. In the present work, the mechanism and kinetics of thermal decomposition of decabromobiphenyl (deca-BB), one of the most frequently-used PBB congeners, are studied in detail using quantum chemical calculations. Results indicate that the high bond dissociation energies and large energy gap of deca-BB make its self-decomposition reaction difficult to occur, while its reactions with several reactive radicals (including hydrogen, bromine, and hydroxyl radicals) in the combustion environment are universally carried out at low energy barriers. Hydrogen, bromine, and hydroxyl radicals all exhibit a high selectivity for the para-C/Br atoms of deca-BB, resulting in the generation of several debromination products or intermediates. This study also investigates the formation mechanism of polybrominated dibenzofurans (PBDFs) from deca-BB and the effect of polymeric materials on this process. We found that the oxidation of ortho-phenyl-type radical, followed by evolution into PBDFs, is a very exothermic and relatively low-barrier process. Thus, the emergence of ortho-phenyl-type radicals from the loss of ortho-Br atoms is a critical step in the formation of PBDFs. Influence of polymeric materials on the formation of PBDFs is reflected in that various alkyl radicals and diradicals produced by their decomposition can readily abstract ortho-Br atoms to generate ortho-phenyl-type radicals, thus facilitating the formation of PBDFs. The mechanistic pathways and kinetic parameters presented in this study can offer theoretical guidance for controlling contaminant emissions in the thermal treatment of deca-BB-containing waste.

Persistent organic pollutants exposure and risk of depression: A systematic review and meta-analysis

Recently, more and more epidemiological studies have examined the impact of exposure to persistent organic pollutants (POPs) on depression, but the results are inconsistent. Thus, we conducted a systematic review and meta-analysis to better understand the effects of POPs exposure on the risk of depression in the general population. We searched PubMed, Embase, Web of Science, and Scopus databases for studies before March 20, 2024. Random-effects meta-analysis was applied to calculate pooled relative risk (OR) and 95% confidence intervals (CIs). We also assessed potential heterogeneity and publication bias across studies and conducted sensitivity analysis. A total of 26 studies were included, and the results indicated that exposure to ΣPBDEs, PBDE-47, and PBDE-99 increased the risk of depression, with OR of 1.37 (95 % CI = 1.06-1.79), 1.30 (95% CI = 1.08-1.56), 1.46 (95 % CI = 1.00-2.12) respectively. On the contrary, the exposure assessment results of PFOS showed a negative correlation with the risk of depression. There is no association between exposure to ΣPFAS, ΣPCBs, and ΣOCPs and increased risk of depression. More standardized studies and more samples are needed in the future to confirm the findings of this study. This finding could provide theoretical references for the prevention and management of depression and offer insights for the risk assessment of POPs exposure.

Developmental exposures to common environmental pollutants result in long-term Reprogramming of hypothalamic-pituitary axis in mice

Humans are exposed to a range of endocrine disrupting chemicals (EDCs). Many studies demonstrate that exposures to EDCs during critical windows of development can permanently affect endocrine health outcomes. Most experimental studies address changes in secretion of hormones produced by gonads, thyroid gland and adrenals, and little is known about the ability of EDCs to produce long-term changes in the hypothalamic-pituitary (HP) control axes. Here, we examined the long-term effects of three common EDCs on male mouse HP gene expression, following developmental exposures. Pregnant mice were exposed to 0.2 mg/ml solutions of bisphenol S (BPS), 2,2',4,4'-tetrabromodiphenyl ether (BDE-47), or 3,3',5,5'-tetrabromobisphenol A (TBBPA) from pregnancy day 8 through lactation day 21 (weaning day). Male offspring were left untreated until postnatal day 140, where pituitaries and hypothalami were collected. Pituitaries were assed for gene expression via RNA sequencing, while specific genes were assessed for expression in hypothalami via RT-qPCR. Differential expression, as well as gene enrichment and pathway analysis, indicated that all three chemicals induced long-term changes, (mostly suppression) in pituitary genes involved in its endocrine function. BPS and BDE-47 produced effects overlapping significantly at the level of effected genes and pathways. All three chemicals altered pathways of gonad and liver HP axes, while BPS altered HP-adrenal and BDE-47 altered HP-thyroid pathways specifically. All three chemicals reduced expression of immune genes in the pituitaries. Targeted gene expression in the hypothalamus indicates down regulation of hypothalamic endocrine control genes by BPS and BDE-47 groups, concordant with changes in the pituitary, suggesting that these chemicals suppress overall HP endocrine function. Interestingly, all three chemicals altered pituitary genes of GPCR-mediated intracellular signaling molecules, key signalers common to many pituitary responses to hormones. The results of this study show that developmental exposures to common EDCs have long-term impacts on hormonal feedback control at the hypothalamic-pituitary level.

Effects of organic and inorganic contaminants and their mixtures on metabolic health and gene expression in developmentally exposed zebrafish

Organic and inorganic chemicals co-occur in household dust, and these chemicals have been determined to have endocrine and metabolic disrupting effects. While there is increasing study of chemical mixtures, the effects of complex mixtures mimicking household dust and other environmental matrices have not been well studied and their potential metabolism disrupting effects are thus poorly understood. Previous research has demonstrated high potency adipogenic effects of residential household dust extracts using in vitro adipogenesis assays. More recent research simplified this to a mixture relevant to household dust and comprised of common co-occurring organic and inorganic contaminants, finding that these complex combinations often exhibited additive or even synergistic effects in cell models. This study aimed to translate our previous in vitro observation to an in vivo model, the developing zebrafish, to evaluate the metabolic effects of early exposure to organic and inorganic chemicals, individually and in mixtures. Zebrafish embryos were exposed from 1 day post fertilization (dpf) to 6 dpf, then metabolic energy expenditure, swimming behavior and gene expression were measured. Globally, we observed that most mixtures did not reflect the effects of individual chemicals; the BFR mixture produced a less potent effect when compared to the individual chemicals, while the PFAS and the inorganic mixtures seemed to have a more potent effect than the individual chemicals. Finally, the environmental mixture, mimicking household dust proportions, was less potent than the inorganic chemical mix alone. Additional work is necessary to better understand the mixture effect of inorganic and organic chemicals combined.

Fluorinated Liquid-Crystal Monomers in Serum from the General Population and Their Impact on Human Health

Fluorinated liquid-crystal monomers (FLCMs) are a potential emerging class of persistent, bioaccumulative, and toxic compounds. Humans inevitably ingest FLCMs via food and the environment. However, there are limited studies on internal exposure biomonitoring of FLCMs. Herein, we evaluated the estimated daily intakes (EDIs) of FLCMs in the general population based on serum residue levels. For the first time, 38 FLCMs were detected in 314 serum samples from the general population in Beijing, with a median value of 132.48 ng/g of lipid weight (lw). BDPrB is a predominant FLCM in serum. The median EDI of ∑38FLCMs in the general residents was 37.96 pg/kg bw/day. The residual levels of most FLCMs were higher in urban than in suburban areas (p < 0.05). The concentrations of EFPEB, EDPrB, EDFPBB, and PDTFMTFT in serum showed positive associations with blood glucose (GLU) (r = 0.126-0.275, p < 0.05). Logistic regression analysis showed that FLCMs were significantly positively correlated with dyslipidemia, with an odds ratio of 2.19; BDPrB was significantly positively correlated with hyperglycemia (OR: 2.48). Overall, the present study suggests the occurrence of FLCMs in the nonoccupational population, and the exposure of certain FLCMs may cause abnormal blood glucose and lipid levels.

Chronic exposure to BDE-47 aggravates acute pancreatitis and chronic pancreatitis by promoting acinar cell apoptosis and inflammation

The effect of 2,2',4,4'-tetrabromodiphenyl ether (BDE-47), a persistent environmental pollutant commonly used as a flame retardant in various consumer products, on pancreatitis has not been clearly elucidated, although it has been reported to be toxic to the liver, nervous system, and reproductive system. Acute pancreatitis (AP) and chronic pancreatitis (CP) models were induced in this study by intraperitoneal injection of caerulein. The aim was to investigate the impact of BDE-47 on pancreatitis by exposing the animals to acute (1 week) or chronic (8 weeks) doses of BDE-47 (30 mg/kg in the low-concentration group and 100 mg/kg in the high-concentration group). Additionally, BDE-47 was utilized to stimulate mouse bone marrow-derived macrophages, pancreatic primary stellate cells, and acinar cells in order to investigate the impact of BDE-47 on pancreatitis. In vivo experiments conducted on mice revealed that chronic exposure to BDE-47, rather than acute exposure, exacerbated the histopathological damage of AP and CP, leading to elevated fibrosis in pancreatic tissue and increased infiltration of inflammatory cells in the pancreas. In vitro experiments showed that BDE-47 can promote the expression of the inflammatory cytokines Tnf-α and Il-6 in M1 macrophages, as well as promote acinar cell apoptosis through the activation of the PERK and JNK pathways via endoplasmic reticulum stress. The findings of this study imply chronic exposure to BDE-47 may exacerbate the progression of both AP and CP by inducing acinar cell apoptosis and dysregulating inflammatory responses.

Changes in Adipose Tissue and Circulating Concentrations of Persistent Organic Pollutants in Midlife Women

Polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) are persistent organic pollutants (POPs) that bioaccumulate in adipose tissue. We investigated the relationship between change in central adiposity and changes in circulating concentrations of POPs over a 12-year period during the midlife. Serum concentrations of 34 PCBs and 19 OCPs were measured at four time points (1999/2000, 2002/03, 2005/06, 2009/11) in a cohort of midlife women, the Study of Women's Health Across the Nation. Linear mixed models were used to test the association between a change in waist circumference and a change in serum POP concentrations. Sixty-five women contributed 181 PCB observations. Fifty-nine women contributed 151 OCP observations. After adjustment for covariates (study site, race and ethnicity, age at baseline, parity), a one-inch (2.54 cm) increase in the change in waist circumference between visits was associated with a 4.9% decrease in the change in serum concentration of PCB 194 (95% CI: -8.0%, -1.6%). No associations were observed for other PCB congeners or the presence of OCPs. An increase in the difference in waist circumference over time was not associated with a change in the difference in serum concentrations of PCBs and OCPs except for PCB 194, possibly due to the high lipophilicity.

Exploring autism spectrum disorder (ASD) and attention deficit disorder (ADD/ADHD) in children exposed to polybrominated biphenyl

Background

Although the causes of attention-deficit/hyperactivity disorder (ADHD) and autism have not been identified, exposure to endocrine-disrupting chemicals, such as polybrominated biphenyl (PBB), during fetal development and early life has been suspected to impact neurological development. This study aims to investigate the association between prenatal and early life exposure to PBB and the development of ADHD and autism later in life.

Methods

Data from the Michigan PBB Registry, a cohort of Michigan residents who had been exposed to PBB in a mass contamination event in 1973, was leveraged for this nested case-control analysis among two distinct samples: (1) Those who self-reported ADHD or autism diagnosis, and (2) mothers who reported their child's ADHD or autism diagnosis. PBB exposure was measured in participants of the PBB Registry, and the mother's PBB level was used in mother-reported analyses. Cases were matched with controls by sex and year of birth. Conditional logistic regression models were used to estimate the association between PBB level and case status.

Results

PBB levels were higher among those who were exposed in early life compared with those exposed in utero (geometric mean: 0.300 ng/ml vs. 0.016 ng/ml). Among women in this cohort, a higher than expected proportion of self-reported ADHD diagnosis (11.11%), compared with population estimates. PBB was not associated with ADHD or autism in either self-reported or mother-reported analyses.

Conclusions

This study adds to the sparse literature about prenatal and early life exposure to PBB-153 and ADHD and autism. Future studies should examine potential effect modification by sex.

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.

In-utero exposure to polybrominated biphenyl (PBB) and menstrual cycle function in adulthood

BACKGROUND

There is evidence that in-utero exposure to PBBs, and similar chemicals, are associated with several adverse reproductive health outcomes including altered pubertal timing. However, less is known about the effects of in-utero exposure to PBBs on menstrual cycle function and reproductive hormone levels in adulthood.

METHODS

For this menstrual cycle study, we recruited reproductive-aged women in the Michigan PBB Registry who were not pregnant, lactating, or taking hormonal medications (2004-2014). A total of 41 women who were born after the PBB contamination incident (1973-1974) and were prenatally exposed to PBBs, were included in this analysis. We estimated in-utero PBB exposure using maternal serum PBB measurements taken after exposure and extrapolated to time of pregnancy using a PBB elimination model. Women were followed for up to 6 months during which they provided daily urine samples and completed daily diaries. The urine samples were assayed for estrone 3-glucuronide (E13G), pregnanediol 3-glucuronide (Pd3G), and follicle stimulating hormone (FSH).

RESULTS

Women in our study were, on average, 27.5 (SD:5.3) years old and contributed 4.9 (SD:1.9) menstrual cycles of follow-up. Compared to women with low in-utero PBB exposure (≤1 ppb), women with medium (>1.0-3.0 ppb) and high (>3.0 ppb) exposure had higher maximum 3-day mean Pd3G levels during the luteal phase. Specifically, the age- and creatinine-adjusted maximum 3-day mean luteal phase Pd3G levels (95% CI) in increasing categories of in-utero PBB exposure were 9.2 (4.6,13.9), 14.8 (11.6,18.0), and 16.1 (12.9,19.3) μg/mg creatinine. There were no meaningful differences in average cycle length, follicular or luteal phase cycle length, bleed length, or creatinine-adjusted E13G or FSH levels by category of in-utero PBB exposure.

CONCLUSION

Higher exposure to PBB in-utero was associated with increased progesterone levels across the luteal phase, however, most other menstrual cycle characteristics were largely unassociated with in-utero PBB exposure. Given our modest sample size, our results require cautious interpretation.

Polybrominated biphenyls (PBBs) and prevalence of autoimmune disorders among members of the Michigan PBB registry

BACKGROUND

Polybrominated biphenyls (PBBs), a class of endocrine disrupting chemicals, were the main chemicals present in one of the largest industrial accidents in the United States. We investigated the association between serum PBB-153 levels and autoimmune disorders among members of the Michigan PBB Registry.

METHODS

Eight hundred and ninety-five members of the registry had both a serum PBB-153 measurement and had completed one or more questionnaires about autoimmune disorders. Autoimmune disorders were examined collectively and within specific organ systems. Sex-stratified unadjusted and adjusted log-binomial models were used to examine the association between tertiles of serum PBB-153 levels and autoimmune disorders. Models were adjusted by lifestage at exposure (in utero, childhood, adulthood), smoking history (never, past, current), and total serum lipid levels (continuous). We utilized cubic spline models to investigate non-linearity between serum PBB-153 levels and the prevalence of autoimmune disorders.

RESULTS

Approximately 12.9% and 20.7% of male and female participants reported having one or more autoimmune disorders, respectively. After adjustment for potential confounders, we observed no association between PBB-153 tertiles and the composite classification of 'any autoimmune disorder' in either sex. We observed some evidence for an association between serum PBB-153 levels and rheumatoid arthritis in males and females; however, this was not statistically significant in females. We also observed some evidence for an association between serum PBB-153 levels and neurological- and thyroid-related autoimmune disorders in females, but again this was not statistically significant. Additionally, we identified dose-response curves for serum PBB-153 levels and the prevalence of autoimmune disorders that differed by lifestage of exposure and sex.

CONCLUSIONS

We observed some evidence that increasing serum PBB-153 levels were associated with three specified autoimmune disorders. Studies focusing on these three autoimmune disorders and the potential non-linear trend differences by lifestage of exposure warrant further investigation.

The Covalent Linking of Organophosphorus Heterocycles to Date Palm Wood-Derived Lignin: Hunting for New Materials with Flame-Retardant Potential

Environmentally acceptable and renewably sourced flame retardants are in demand. Recent studies have shown that the incorporation of the biopolymer lignin into a polymer can improve its ability to form a char layer upon heating to a high temperature. Char layer formation is a central component of flame-retardant activity. The covalent modification of lignin is an established technique that is being applied to the development of potential flame retardants. In this study, four novel modified lignins were prepared, and their char-forming abilities were assessed using thermogravimetric analysis. The lignin was obtained from date palm wood using a butanosolv pretreatment. The removal of the majority of the ester groups from this heavily acylated lignin was achieved via alkaline hydrolysis. The subsequent modification of the lignin involved the incorporation of an azide functional group and copper-catalysed azide-alkyne cycloaddition reactions. These reactions enabled novel organophosphorus heterocycles to be linked to the lignin. Our preliminary results suggest that the modified lignins had improved char-forming activity compared to the controls. 31P and HSQC NMR and small-molecule X-ray crystallography were used to analyse the prepared compounds and lignins.

Serum levels of PCDDs, PCDFs and dl-PCBs in general population residing far and near from an urban waste treatment plant under construction in Gipuzkoa, Basque Country (Spain)

This research focused on investigating the basal serum concentrations of polychlorinated dibenzo-p-dioxins, dibenzofurans (PCDD/Fs) and dioxin-like polychlorinated biphenyls (dl-PCBs) in the general population residing in two urban-industrial zones near and far from an energy recovery plant under construction in Gipuzkoa, Basque Country (Spain). The study used a cross-sectional design and included 227 participants who were randomly selected from municipal censuses in both areas. The participants were stratified based on age (ranging from 18 to 70 years) and sex. Serum samples were collected from the participants and analysed following the established protocol to measure the concentrations of PCDD/Fs and dl-PCBs. The study used multiple linear regression models to assess the impact of various sociodemographic variables, lifestyle factors, reproductive history, and diet on the variability of the measured compounds in the participants' serum. The median total toxicity equivalent (TEQ) in serum, was 10.58 pg WHO-TEQ2005 g-1 lipid. Serum PCDD levels were lower in the population residing in the "far" zone than the "near" zone. Age was positively associated with both PCDD/F and dl-PCB levels, indicating that older participants had higher concentrations of these compounds in their serum. This finding might be attributed to cumulative exposure over time. In terms of sex differences, women exhibited lower levels of dl-PCBs compared to men. Among lifestyle factors, smokers showed lower levels of dl-PCBs compared to non-smokers. Furthermore, daily alcohol consumption was significantly associated with higher serum levels of these compounds, with daily drinkers showing higher levels than non-drinkers. Consumption of local poultry was associated with significantly higher serum levels and oil consumption with low levels of PCDD/Fs.

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

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

Assessing Metabolic Differences Associated with Exposure to Polybrominated Biphenyl and Polychlorinated Biphenyls in the Michigan PBB Registry

BACKGROUND

Polybrominated biphenyls (PBB) and polychlorinated biphenyls (PCB) are persistent organic pollutants with potential endocrine-disrupting effects linked to adverse health outcomes.

OBJECTIVES

In this study, we utilize high-resolution metabolomics (HRM) to identify internal exposure and biological responses underlying PCB and multigenerational PBB exposure for participants enrolled in the Michigan PBB Registry.

METHODS

HRM profiling was conducted on plasma samples collected from 2013 to 2014 from a subset of participants enrolled in the Michigan PBB Registry, including 369 directly exposed individuals (F0) who were alive when PBB mixtures were accidentally introduced into the food chain and 129 participants exposed to PBB in utero or through breastfeeding, if applicable (F1). Metabolome-wide association studies were performed for PBB-153 separately for each generation and Σ PCB (PCB-118, PCB-138, PCB-153, and PCB-180) in the two generations combined, as both had direct PCB exposure. Metabolite and metabolic pathway alterations were evaluated following a well-established untargeted HRM workflow.

RESULTS

Mean levels were 1.75  ng / mL [standard deviation (SD): 13.9] for PBB-153 and 1.04  ng / mL (SD: 0.788) for Σ PCB . Sixty-two and 26 metabolic features were significantly associated with PBB-153 in F0 and F1 [false discovery rate (FDR) p < 0.2 ], respectively. There were 2,861 features associated with Σ PCB (FDR p < 0.2 ). Metabolic pathway enrichment analysis using a bioinformatics tool revealed perturbations associated with Σ PCB in numerous oxidative stress and inflammation pathways (e.g., carnitine shuttle, glycosphingolipid, and vitamin B9 metabolism). Metabolic perturbations associated with PBB-153 in F0 were related to oxidative stress (e.g., pentose phosphate and vitamin C metabolism) and in F1 were related to energy production (e.g., pyrimidine, amino sugars, and lysine metabolism). Using authentic chemical standards, we confirmed the chemical identity of 29 metabolites associated with Σ PCB levels (level 1 evidence).

CONCLUSIONS

Our results demonstrate that serum PBB-153 is associated with alterations in inflammation and oxidative stress-related pathways, which differed when stratified by generation. We also found that Σ PCB was associated with the downregulation of important neurotransmitters, serotonin, and 4-aminobutanoate. These findings provide novel insights for future investigations of molecular mechanisms underlying PBB and PCB exposure on health. https://doi.org/10.1289/EHP12657.

Adipogenic and endocrine disrupting mixture effects of organic and inorganic pollutant mixtures

Chronic health conditions are rapidly increasing in prevalence and cost to society worldwide: in the US, >42 % of adults aged 20 and older are currently classified as obese. Exposure to endocrine disrupting chemicals (EDCs) has been implicated as a causal factor; some EDCs, termed "obesogens", can increase weight and lipid accumulation and/or perturb metabolic homeostasis. This project aimed to assess the potential combination effects of diverse inorganic and organic contaminant mixtures, which more closely reflect environmentally realistic exposures, on nuclear receptor activation/inhibition and adipocyte differentiation. Herein, we focused on two polychlorinated biphenyls (PCB-77 and 153), two perfluoroalkyl substances (PFOA and PFOS), two brominated flame retardants (PBB-153 and BDE-47), and three inorganic contaminants (lead, arsenic, and cadmium). We examined adipogenesis using human mesenchymal stem cells and receptor bioactivities using luciferase reporter gene assays in human cell lines. We observed significantly greater effects for several receptor bioactivities by various contaminant mixtures relative to individual components. All nine contaminants promoted triglyceride accumulation and/or pre-adipocyte proliferation in human mesenchymal stem cells. Comparing simple component mixtures to individual components at 10 % and 50 % effect levels revealed putative synergistic effects for each of the mixtures for at least one of the concentrations relative to the individual component chemicals, some of which also exhibited significantly greater effects than the component contaminants. Our results support further testing of more realistic and complex contaminant mixtures that better reflect environmental exposures, in order to more conclusively define mixture responses both in vitro and in vivo.

Assessing disparities in Americans' exposure to PCBs and PBDEs based on NHANES pooled biomonitoring data

The National Health and Nutrition Examination Survey (NHANES) has been continuously biomonitoring Americans' exposure to two families of harmful environmental chemicals: polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs). However, biomonitoring these chemicals is expensive. To save cost, in 2005, NHANES resorted to pooled biomonitoring; i.e., amalgamating individual specimens to form a pool and measuring chemical levels from pools. Despite being publicly available, these pooled data gain limited applications in health studies. Among the few studies using these data, racial/age disparities were detected, but there is no control for confounding effects. These disadvantages are due to the complexity of pooled measurements and a dearth of statistical tools. Herein, we developed a regression-based method to unzip pooled measurements, which facilitated a comprehensive assessment of disparities in exposure to these chemicals. We found increasing dependence of PCBs on age and income, whereas PBDEs were the highest among adolescents and seniors and were elevated among the low-income population. In addition, Hispanics had the lowest PCBs and PBDEs among all demographic groups after controlling for potential confounders. These findings can guide the development of population-specific interventions to promote environmental justice. Moreover, both chemical levels declined throughout the period, indicating the effectiveness of existing regulatory policies.

The Minderoo-Monaco Commission on Plastics and Human Health

Background

Plastics have conveyed great benefits to humanity and made possible some of the most significant advances of modern civilization in fields as diverse as medicine, electronics, aerospace, construction, food packaging, and sports. It is now clear, however, that plastics are also responsible for significant harms to human health, the economy, and the earth's environment. These harms occur at every stage of the plastic life cycle, from extraction of the coal, oil, and gas that are its main feedstocks through to ultimate disposal into the environment. The extent of these harms not been systematically assessed, their magnitude not fully quantified, and their economic costs not comprehensively counted.

Goals

The goals of this Minderoo-Monaco Commission on Plastics and Human Health are to comprehensively examine plastics' impacts across their life cycle on: (1) human health and well-being; (2) the global environment, especially the ocean; (3) the economy; and (4) vulnerable populations-the poor, minorities, and the world's children. On the basis of this examination, the Commission offers science-based recommendations designed to support development of a Global Plastics Treaty, protect human health, and save lives.

Report Structure

This Commission report contains seven Sections. Following an Introduction, Section 2 presents a narrative review of the processes involved in plastic production, use, and disposal and notes the hazards to human health and the environment associated with each of these stages. Section 3 describes plastics' impacts on the ocean and notes the potential for plastic in the ocean to enter the marine food web and result in human exposure. Section 4 details plastics' impacts on human health. Section 5 presents a first-order estimate of plastics' health-related economic costs. Section 6 examines the intersection between plastic, social inequity, and environmental injustice. Section 7 presents the Commission's findings and recommendations.

Plastics

Plastics are complex, highly heterogeneous, synthetic chemical materials. Over 98% of plastics are produced from fossil carbon- coal, oil and gas. Plastics are comprised of a carbon-based polymer backbone and thousands of additional chemicals that are incorporated into polymers to convey specific properties such as color, flexibility, stability, water repellence, flame retardation, and ultraviolet resistance. Many of these added chemicals are highly toxic. They include carcinogens, neurotoxicants and endocrine disruptors such as phthalates, bisphenols, per- and poly-fluoroalkyl substances (PFAS), brominated flame retardants, and organophosphate flame retardants. They are integral components of plastic and are responsible for many of plastics' harms to human health and the environment.Global plastic production has increased almost exponentially since World War II, and in this time more than 8,300 megatons (Mt) of plastic have been manufactured. Annual production volume has grown from under 2 Mt in 1950 to 460 Mt in 2019, a 230-fold increase, and is on track to triple by 2060. More than half of all plastic ever made has been produced since 2002. Single-use plastics account for 35-40% of current plastic production and represent the most rapidly growing segment of plastic manufacture.Explosive recent growth in plastics production reflects a deliberate pivot by the integrated multinational fossil-carbon corporations that produce coal, oil and gas and that also manufacture plastics. These corporations are reducing their production of fossil fuels and increasing plastics manufacture. The two principal factors responsible for this pivot are decreasing global demand for carbon-based fuels due to increases in 'green' energy, and massive expansion of oil and gas production due to fracking.Plastic manufacture is energy-intensive and contributes significantly to climate change. At present, plastic production is responsible for an estimated 3.7% of global greenhouse gas emissions, more than the contribution of Brazil. This fraction is projected to increase to 4.5% by 2060 if current trends continue unchecked.

Plastic Life Cycle

The plastic life cycle has three phases: production, use, and disposal. In production, carbon feedstocks-coal, gas, and oil-are transformed through energy-intensive, catalytic processes into a vast array of products. Plastic use occurs in every aspect of modern life and results in widespread human exposure to the chemicals contained in plastic. Single-use plastics constitute the largest portion of current use, followed by synthetic fibers and construction.Plastic disposal is highly inefficient, with recovery and recycling rates below 10% globally. The result is that an estimated 22 Mt of plastic waste enters the environment each year, much of it single-use plastic and are added to the more than 6 gigatons of plastic waste that have accumulated since 1950. Strategies for disposal of plastic waste include controlled and uncontrolled landfilling, open burning, thermal conversion, and export. Vast quantities of plastic waste are exported each year from high-income to low-income countries, where it accumulates in landfills, pollutes air and water, degrades vital ecosystems, befouls beaches and estuaries, and harms human health-environmental injustice on a global scale. Plastic-laden e-waste is particularly problematic.

Environmental Findings

Plastics and plastic-associated chemicals are responsible for widespread pollution. They contaminate aquatic (marine and freshwater), terrestrial, and atmospheric environments globally. The ocean is the ultimate destination for much plastic, and plastics are found throughout the ocean, including coastal regions, the sea surface, the deep sea, and polar sea ice. Many plastics appear to resist breakdown in the ocean and could persist in the global environment for decades. Macro- and micro-plastic particles have been identified in hundreds of marine species in all major taxa, including species consumed by humans. Trophic transfer of microplastic particles and the chemicals within them has been demonstrated. Although microplastic particles themselves (>10 µm) appear not to undergo biomagnification, hydrophobic plastic-associated chemicals bioaccumulate in marine animals and biomagnify in marine food webs. The amounts and fates of smaller microplastic and nanoplastic particles (MNPs <10 µm) in aquatic environments are poorly understood, but the potential for harm is worrying given their mobility in biological systems. Adverse environmental impacts of plastic pollution occur at multiple levels from molecular and biochemical to population and ecosystem. MNP contamination of seafood results in direct, though not well quantified, human exposure to plastics and plastic-associated chemicals. Marine plastic pollution endangers the ocean ecosystems upon which all humanity depends for food, oxygen, livelihood, and well-being.

Human Health Findings

Coal miners, oil workers and gas field workers who extract fossil carbon feedstocks for plastic production suffer increased mortality from traumatic injury, coal workers' pneumoconiosis, silicosis, cardiovascular disease, chronic obstructive pulmonary disease, and lung cancer. Plastic production workers are at increased risk of leukemia, lymphoma, hepatic angiosarcoma, brain cancer, breast cancer, mesothelioma, neurotoxic injury, and decreased fertility. Workers producing plastic textiles die of bladder cancer, lung cancer, mesothelioma, and interstitial lung disease at increased rates. Plastic recycling workers have increased rates of cardiovascular disease, toxic metal poisoning, neuropathy, and lung cancer. Residents of "fenceline" communities adjacent to plastic production and waste disposal sites experience increased risks of premature birth, low birth weight, asthma, childhood leukemia, cardiovascular disease, chronic obstructive pulmonary disease, and lung cancer.During use and also in disposal, plastics release toxic chemicals including additives and residual monomers into the environment and into people. National biomonitoring surveys in the USA document population-wide exposures to these chemicals. Plastic additives disrupt endocrine function and increase risk for premature births, neurodevelopmental disorders, male reproductive birth defects, infertility, obesity, cardiovascular disease, renal disease, and cancers. Chemical-laden MNPs formed through the environmental degradation of plastic waste can enter living organisms, including humans. Emerging, albeit still incomplete evidence indicates that MNPs may cause toxicity due to their physical and toxicological effects as well as by acting as vectors that transport toxic chemicals and bacterial pathogens into tissues and cells.Infants in the womb and young children are two populations at particularly high risk of plastic-related health effects. Because of the exquisite sensitivity of early development to hazardous chemicals and children's unique patterns of exposure, plastic-associated exposures are linked to increased risks of prematurity, stillbirth, low birth weight, birth defects of the reproductive organs, neurodevelopmental impairment, impaired lung growth, and childhood cancer. Early-life exposures to plastic-associated chemicals also increase the risk of multiple non-communicable diseases later in life.

Economic Findings

Plastic's harms to human health result in significant economic costs. We estimate that in 2015 the health-related costs of plastic production exceeded $250 billion (2015 Int$) globally, and that in the USA alone the health costs of disease and disability caused by the plastic-associated chemicals PBDE, BPA and DEHP exceeded $920 billion (2015 Int$). Plastic production results in greenhouse gas (GHG) emissions equivalent to 1.96 gigatons of carbon dioxide (CO2e) annually. Using the US Environmental Protection Agency's (EPA) social cost of carbon metric, we estimate the annual costs of these GHG emissions to be $341 billion (2015 Int$).These costs, large as they are, almost certainly underestimate the full economic losses resulting from plastics' negative impacts on human health and the global environment. All of plastics' economic costs-and also its social costs-are externalized by the petrochemical and plastic manufacturing industry and are borne by citizens, taxpayers, and governments in countries around the world without compensation.

Social Justice Findings

The adverse effects of plastics and plastic pollution on human health, the economy and the environment are not evenly distributed. They disproportionately affect poor, disempowered, and marginalized populations such as workers, racial and ethnic minorities, "fenceline" communities, Indigenous groups, women, and children, all of whom had little to do with creating the current plastics crisis and lack the political influence or the resources to address it. Plastics' harmful impacts across its life cycle are most keenly felt in the Global South, in small island states, and in disenfranchised areas in the Global North. Social and environmental justice (SEJ) principles require reversal of these inequitable burdens to ensure that no group bears a disproportionate share of plastics' negative impacts and that those who benefit economically from plastic bear their fair share of its currently externalized costs.

Conclusions

It is now clear that current patterns of plastic production, use, and disposal are not sustainable and are responsible for significant harms to human health, the environment, and the economy as well as for deep societal injustices.The main driver of these worsening harms is an almost exponential and still accelerating increase in global plastic production. Plastics' harms are further magnified by low rates of recovery and recycling and by the long persistence of plastic waste in the environment.The thousands of chemicals in plastics-monomers, additives, processing agents, and non-intentionally added substances-include amongst their number known human carcinogens, endocrine disruptors, neurotoxicants, and persistent organic pollutants. These chemicals are responsible for many of plastics' known harms to human and planetary health. The chemicals leach out of plastics, enter the environment, cause pollution, and result in human exposure and disease. All efforts to reduce plastics' hazards must address the hazards of plastic-associated chemicals.

Recommendations

To protect human and planetary health, especially the health of vulnerable and at-risk populations, and put the world on track to end plastic pollution by 2040, this Commission supports urgent adoption by the world's nations of a strong and comprehensive Global Plastics Treaty in accord with the mandate set forth in the March 2022 resolution of the United Nations Environment Assembly (UNEA).International measures such as a Global Plastics Treaty are needed to curb plastic production and pollution, because the harms to human health and the environment caused by plastics, plastic-associated chemicals and plastic waste transcend national boundaries, are planetary in their scale, and have disproportionate impacts on the health and well-being of people in the world's poorest nations. Effective implementation of the Global Plastics Treaty will require that international action be coordinated and complemented by interventions at the national, regional, and local levels.This Commission urges that a cap on global plastic production with targets, timetables, and national contributions be a central provision of the Global Plastics Treaty. We recommend inclusion of the following additional provisions:The Treaty needs to extend beyond microplastics and marine litter to include all of the many thousands of chemicals incorporated into plastics.The Treaty needs to include a provision banning or severely restricting manufacture and use of unnecessary, avoidable, and problematic plastic items, especially single-use items such as manufactured plastic microbeads.The Treaty needs to include requirements on extended producer responsibility (EPR) that make fossil carbon producers, plastic producers, and the manufacturers of plastic products legally and financially responsible for the safety and end-of-life management of all the materials they produce and sell.The Treaty needs to mandate reductions in the chemical complexity of plastic products; health-protective standards for plastics and plastic additives; a requirement for use of sustainable non-toxic materials; full disclosure of all components; and traceability of components. International cooperation will be essential to implementing and enforcing these standards.The Treaty needs to include SEJ remedies at each stage of the plastic life cycle designed to fill gaps in community knowledge and advance both distributional and procedural equity.This Commission encourages inclusion in the Global Plastic Treaty of a provision calling for exploration of listing at least some plastic polymers as persistent organic pollutants (POPs) under the Stockholm Convention.This Commission encourages a strong interface between the Global Plastics Treaty and the Basel and London Conventions to enhance management of hazardous plastic waste and slow current massive exports of plastic waste into the world's least-developed countries.This Commission recommends the creation of a Permanent Science Policy Advisory Body to guide the Treaty's implementation. The main priorities of this Body would be to guide Member States and other stakeholders in evaluating which solutions are most effective in reducing plastic consumption, enhancing plastic waste recovery and recycling, and curbing the generation of plastic waste. This Body could also assess trade-offs among these solutions and evaluate safer alternatives to current plastics. It could monitor the transnational export of plastic waste. It could coordinate robust oceanic-, land-, and air-based MNP monitoring programs.This Commission recommends urgent investment by national governments in research into solutions to the global plastic crisis. This research will need to determine which solutions are most effective and cost-effective in the context of particular countries and assess the risks and benefits of proposed solutions. Oceanographic and environmental research is needed to better measure concentrations and impacts of plastics <10 µm and understand their distribution and fate in the global environment. Biomedical research is needed to elucidate the human health impacts of plastics, especially MNPs.

Summary

This Commission finds that plastics are both a boon to humanity and a stealth threat to human and planetary health. Plastics convey enormous benefits, but current linear patterns of plastic production, use, and disposal that pay little attention to sustainable design or safe materials and a near absence of recovery, reuse, and recycling are responsible for grave harms to health, widespread environmental damage, great economic costs, and deep societal injustices. These harms are rapidly worsening.While there remain gaps in knowledge about plastics' harms and uncertainties about their full magnitude, the evidence available today demonstrates unequivocally that these impacts are great and that they will increase in severity in the absence of urgent and effective intervention at global scale. Manufacture and use of essential plastics may continue. However, reckless increases in plastic production, and especially increases in the manufacture of an ever-increasing array of unnecessary single-use plastic products, need to be curbed.Global intervention against the plastic crisis is needed now because the costs of failure to act will be immense.

Associations of brominated flame retardants exposure with chronic obstructive pulmonary disease: A US population-based cross-sectional analysis

Backgrounds

Whether there existed an association between brominated flame retardants (BFRs) and chronic obstructive pulmonary disease (COPD) prevalence in humans is still a mystery.

Objective

To investigate the association between serum single or mixture BFRs and COPD prevalence.

Methods

Data of 7,591 participants from NHANES 2007–2016 was utilized. Serum BFRs, including PBDE-28, PBDE-47, PBDE-85, PBDE-99, PBDE-100, PBDE-154, PBDE-183, PBDE-209, and PBB-153 were enrolled. The survey-weighted generalized logistic regression model, restricted cubic splines (RCS), weighted quantile sum (WQS) regression, and quantile-based g-computation (QGC) analysis were performed.

Results

After adjustment for all confounding factors, log-transformed continuous serum PBDE-28 (OR: 1.43; 95% CI: 1.10–1.85; P = 0.01), PBDE-47 (OR: 1.39; 95% CI: 1.11–1.75; P = 0.005), PBDE-85 (OR: 1.31; 95% CI: 1.09–1.57; P = 0.005), PBDE-99 (OR: 1.27; 95% CI: 1.05–1.54; P = 0.02), PBDE-100 (OR: 1.33; 95% CI: 1.08–1.66; P = 0.01), PBDE-154 (OR: 1.29; 95% CI: 1.07–1.55; P = 0.01), PBDE-183 (OR: 1.31; 95% CI: 1.04–1.66; P = 0.02), and PBB-153 (OR: 1.25; 95% CI: 1.03–1.53; P = 0.03) were positively correlated with the prevalence of COPD. Restricted cubic splines curves displayed that PBDE-209 was significantly associated with CPOD in an inverted U-shape (P = 0.03). A significant interaction between being male and a high prevalence of COPD was observed for PBDE-28 (P for interaction &lt;0.05), PBDE-47 (P for interaction &lt;0.05), PBDE-85 (P for interaction &lt;0.05), PBDE-99 (P for interaction &lt;0.05), PBDE-100 (P for interaction &lt;0.05), and PBB-153 (P for interaction &lt; 0.05). Mixture BFRs exposure was positively associated with COPD prevalence in WQS regression (OR: 1.40; 95% CI: 1.14–1.72, P = 0.002) and in QGC analysis (OR: 1.49; 95% CI: 1.27–1.74, P &lt; 0.001).

Conclusions

Our study confirms that individual and mixture BFRs had positive associations with COPD, and further studies are required in larger-scale populations.

Elimination of PBB-153; findings from a cohort of Michigan adults

BACKGROUND

An industrial accident led to the widespread contamination of polybrominated biphenyl (PBB), a flame retardant, into the food system in Michigan in the 1970's. PBB continues to be detected in Michiganders' blood some forty years later. It is necessary to understand the elimination rate and half-life of PBB because it may provide clues on how to hasten the elimination of it from the human body.

METHODS

Serum samples were taken from young adult and adult participants of the Michigan PBB registry from 1974 to 2019. A single compartment model was assumed for the elimination rate for PBB-153 in young adults and adults (≥16 years). Generalized linear mixed models were used to estimate the average elimination rate of PBB-153 and allowed for a random intercept and slope for the time between measurements. Models were adjusted for age at exposure, body mass index (BMI) at initial measurement, and smoking. Models were also stratified by demographic characteristics.

RESULTS

In total, 1974 participants contributed 4768 samples over a forty-year span. The median initial PBB-153 level was 1.542 parts per billion (ppb) (Range: 0.001-1442.48 ppb). The adjusted median participant-specific half-life for PBB-153 was 12.23 years. The half-life of PBB-153 was lengthened by higher initial PBB level (∼1.5 years), younger age at exposure (∼5.4 years), higher BMI (∼1.0 years), and increased gravidity (∼7.3 years). Additionally, the half-life of PBB-153 was shortened by smoking status (∼-2.8 years) and breastfeeding (∼-3.5 years).

CONCLUSIONS

Consistent with previous studies, PBB-153 has been demonstrated to have a long half-life in the human body and may be modified by some demographic characteristics. These updated estimates of half-life will further support evaluation of health effects associated with PBB exposure. Investigations into mechanisms to accelerate elimination and reduce body burdens of PBB-153, especially those related to body weight, are needed.

A probabilistic hazard and risk assessment of exposure to metals and organohalogens associated with a traditional diet in the Indigenous communities of Eeyou Istchee (northern Quebec, Canada)

Hunting, trapping, and fishing are part of an Indigenous lifestyle in subarctic Canada. However, this lifestyle may be a route of exposure to contaminants and may pose a risk for the people who rely on a subsistence diet. Monte Carlo simulations for the chemical concentration of eight game species and one fish species were carried out by randomly sampling 10,000 samples from the contaminant measures for each species. We then calculated a probabilistic non-carcinogenic hazard quotient or carcinogenic risk values to estimate the human health risk of exposure to contaminants. Of the species examined, ducks were of concern for potential carcinogenic risk. There was a modeled probabilistic 95th-percentile risk associated with the consumption of ducks and polybrominated biphenyl (PBB) congener 153 in boys, women, and men (1.09 × 10-6, 1.57 × 10-6, and 2.17 × 10-6, respectively) and, to a lesser extent, with geese and polychlorinated biphenyl (PCB) congener 153 in men (1.19 × 10-6). Contaminant concentration in the intake rate (food consumption) for PBB congener 153 exposure risk was more important than that for PCB congener 153, where intake rate had greater relevance. The consumption of waterfowl may increase the exposure to organohalogens; however, there are health and wellness benefits associated with the harvesting and consumption of subsistence foods that must also be considered. We recommend follow-up species-specific studies focused on ducks to clarify and elucidate the results in the present study.

PBDE-47 induces impairment of mitochondrial biogenesis and subsequent neurotoxicity through miR-128-3p/PGC-1α axis

The potential adverse effects of 2,2',4,4'-tetrabromodiphenyl ether (PBDE-47) on neurons are extensively studied, and mitochondria are identified as critical targets. This study aimed to investigate whether PBDE-47 impairs mitochondrial biogenesis via the miR-128-3p/PGC-1α axis to trigger mitochondrial dysfunction-related neuronal damage. In vitro neuroendocrine pheochromocytoma (PC12) cells and in vivo Sprague Dawley rat model were adopted. In this study, biochemical methods were used to examine mitochondrial ATP content, cell viability, and expressions of key mitochondrial biogenesis regulators, including peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC-1α), nuclear respiratory factor 1 (NRF1), and mitochondrial transcription factor A (TFAM). Mimics and inhibitors of miR-128-3p were employed to explore its role in PBDE-47-induced neurotoxicity. Both in vivo and in vitro evidences suggested that PBDE-47 suppressed PGC-1α/NRF1/TFAM signaling pathways and mitochondrial DNA (mtDNA) encoding proteins synthesis. PBDE-47 also suppressed the relative mtDNA content, mRNA levels of mtDNA-encoded subunits, and mitochondrial ATP levels in vitro. Specifically, 2-(4-tert-butylphenyl) benzimidazole (ZLN005) alleviated PBDE-47-induced neuronal death through the improvement of mitochondrial function by activating PGC-1α/NRF1/TFAM signaling pathways. Mechanistically, PBDE-47 dramatically upregulated miR-128-3p expression. Furthermore, miR-128-3p inhibition enhanced PGC-1α/NRF1/TFAM signaling and abolished PBDE-47-induced impairment of mitochondrial biogenesis. In summary, this study provides in vitro evidence to reveal the role of mitochondrial biogenesis in PBDE-47-induced mitochondrial dysfunction and related neurotoxicity and suggests that miR-128-3p/PGC-1α axis may be a therapeutic target for PBDE-47 neurotoxicity.

Inheritance of paternal lifestyles and exposures through sperm DNA methylation

Many different lifestyle factors and chemicals present in the environment are a threat to the reproductive tracts of humans. The potential for parental preconception exposure to alter gametes and for these alterations to be passed on to offspring and negatively affect embryo growth and development is of concern. The connection between maternal exposures and offspring health is a frequent focus in epidemiological studies, but paternal preconception exposures are much less frequently considered and are also very important determinants of offspring health. Several environmental and lifestyle factors in men have been found to alter sperm epigenetics, which can regulate gene expression during early embryonic development. Epigenetic information is thought to be a mechanism that evolved for organisms to pass on information about their lived experiences to offspring. DNA methylation is a well-studied epigenetic regulator that is sensitive to environmental exposures in somatic cells and sperm. The continuous production of sperm from spermatogonial stem cells throughout a man's adult life and the presence of spermatogonial stem cells outside of the blood-testis barrier makes them susceptible to environmental insults. Furthermore, altered sperm DNA methylation patterns can be maintained throughout development and ultimately result in impairments, which could predispose offspring to disease. Innovations in human stem cell-based spermatogenic models can be used to elucidate the paternal origins of health and disease.

BDE-47 disturbs the immune response of lymphocytes to LPS by downregulating NF-κB pathway

The health risks associated with 2,2',4,4'-tetra-bromodiphenyl ether (BDE-47) have become an increasing concern due to its widespread presence in the environment and biological samples. To date, the potential toxicity of BDE-47 to immune system remains unclear. In this study, we aimed to study the immunotoxicity of BDE-47 using spleen-derived lymphocytes in vitro and BALB/c mice in vivo. In vitro results showed that lymphocytes exposed to 12.5-100 μM BDE-47 exhibited unchanged cell viability but decreased release of IL-6 and TNF-α when responding to lipopolysaccharide (LPS). The expression levels of p-p65, p-IκBα, TrkA and p-Akt involved in NF-κB pathway were obviously decreased, and NF-κB activator PMA could recover the BDE-47-induced inhibitory effect on IL-6 and TNF-α release by lymphocytes in response to LPS. In vivo data showed that BDE-47 orally administered to mice (1 mg/kg, 10 mg/kg, 100 mg/kg per day, 30 days) did not significantly affect body weight, organ index and histomorphology of spleen. However, ELISA assay showed that serum IL-6 and TNF-α levels from BDE-47-treated mice after intraperitoneal injection of LPS were significantly reduced, and high-throughput mouse cytokines screening found 13 more cytokines down-regulated in the serum. Transcriptomic sequencing of spleens identified 488 differential expressed genes (DEGs). GO enrichment analysis of these DEGs suggested that the GO term of response to LPS (GO: 0032,496) was significantly involved. KEGG enrichment analysis showed that the down-regulated DEGs significantly enriched in multiple immune-related signaling pathways including the NF-κB signaling pathway (mmu04064). Overall, these data suggested that BDE-47 could negatively regulate NF-κB signaling pathways to inhibit the immune response of lymphocytes to LPS, suggesting that exposures to BDE-47 may disturb the immune balance and increase the body's susceptibility to infectious diseases.

Birth outcomes associated with paternal polybrominated and polychlorinated biphenyl exposure

In 1973-74, a polybrominated biphenyl (PBB) flame retardant mixture was shipped to Michigan livestock feed mills in place of a nutritional supplement and contaminated the food supply. Following the accident, the Michigan PBB Registry was established to study the long-term health effects of halogenated compounds and is now led by a community-academic partnership. PBB exposure is associated with altered DNA methylation in sperm, which may lead to adverse birth outcomes in children whose fathers have increased levels of serum PBB or polychlorinated biphenyl (PCB). Paternal PBB and PCB levels of men enrolled in the Michigan PBB Registry (n = 155) were analyzed against matched offspring birthweight and gestational age (n = 336). Birthweight and gestational age were dichotomized at the 25th percentile and 37 weeks, respectively, and paternal PBB and PCB levels were examined as continuous measures and divided into tertiles. Associations of offspring birthweight and gestational age with paternal PBB and PCB serum concentrations were modeled using multivariable linear spline and log-risk regression, adjusting for family clustering, paternal health and lifestyle factors, maternal PBB, and PCB serum concentrations, sex, and offspring gestational age (for birthweight). Fathers in the middle and upper PBB and PCB tertiles had increased risks for lowest quartile birthweight compared to the first tertile, with adjusted risk ratios (aRR) = 1.67 (95% CI: 0.93, 2.99) and aRR = 2.06 (95% CI: 1.12, 3.79) for PBB, and aRR = 1.47 (95% CI: 0.79, 2.75) and aRR = 1.34 (95% CI: 0.70, 2.54) for PCB, respectively. Elevated paternal PBB levels were not associated with an increased risk for preterm birth, while PCB levels were associated with a small, but not significant, decrease in gestational age, β = -0.37 (95% CI: -0.76, 0.03) weeks per log unit increase PCB. The findings suggest that increased paternal PBB and PCB levels negatively impact offspring birthweight, and paternal PCB levels may negatively impact gestational age.

The concentration and biomagnification of PCBs and PBDEs across four trophic levels in a marine food web

Contracting Parties to the OSPAR Convention for the Protection of the Maine Environment of the North-East Atlantic are required to undertake monitoring and assessment of both inorganic and organic contaminants. There is a requirement to assess contaminants across different trophic levels on an ecosystem-specific basis. However, this is currently constrained by the availability of relevant samples to cover the full range of trophic levels. This study investigates the variability (inter- and intra-species variation) of the concentrations and distributions of thirty-two polychlorinated biphenyl (PCB) congeners and nine polybrominated diphenyl ether (PBDE) congeners in twenty-six species covering four trophic levels from different geographic locations around Scotland. Trophic magnification factors (TMFs) were calculated using a traditional method and a balanced method for both the ICES-7 PCBs and BDE47, to refine and improve the application of TMFs to assess and predict biomagnification risk to biota in the marine environment. There were clear differences in congener percentage distribution between sample categories and species, with differences influenced by physiological processes and eco-biological parameters. Trophic magnification was found to occur for the ICES-7 PCBs and BDE47 using the traditional method, with the highest degree of trophic magnification reported for CB52. An unbalanced dataset was found to influence the calculated TMF and in some cases, the overall conclusion of the trophic transfer of PCB and PBDE congeners. The balanced method is highly recommended for calculating TMFs to ensure that the TMF is a true indication of the biomagnification potential, particularly when conducting regional comparisons for which sampling requirements are difficult to achieve.

Apoptotic p53 Gene Expression in the Regulation of Persistent Organic Pollutant (POP)-Induced Oxidative Stress in the Intertidal Crab Macrophthalmusjaponicus

Persistent organic pollutants (POPs), some of the most dangerous chemicals released into the aquatic environment, are distributed worldwide due to their environmental persistence and bioaccumulation. In the study, we investigated p53-related apoptotic responses to POPs such as hexabromocyclododecanes (HBCDs) or 2,2′,4,4′-tetrabromodiphenyl ether (BDE-47) in the mud crab Macrophthalmus japonicus. To do so, we characterized M. japonicus p53 and evaluated basal levels of p53 expression in different tissues. M. japonicus p53 has conserved amino acid residues involving sites for protein dimerization and DNA and zinc binding. In phylogenetic analysis, the homology of the deduced p53 amino acid sequence was not high (67−70%) among crabs, although M. japonicus p53 formed a cluster with one clade with p53 homologs from other crabs. Tissue distribution patterns revealed that the highest expression of p53 mRNA transcripts was in the hepatopancreas of M. japonicus crabs. Exposure to POPs induced antioxidant defenses to modulate oxidative stress through the upregulation of catalase expression. Furthermore, p53 expression was generally upregulated in the hepatopancreas and gills of M. japonicus after exposure to most concentrations of HBCD or BDE-47 for all exposure periods. In hepatopancreas tissue, significant increases in p53 transcript levels were observed as long-lasting apoptotic responses involving cellular defenses until day 7 of relative long-term exposure. The findings in this study suggest that exposure to POPs such as HBCD or BDE-47 may trigger the induction of cellular defense processes against oxidative stress, including DNA repair, cell cycle arrest, and apoptosis through the transcriptional upregulation of p53 expression in M. japonicus.

BDE-47 induces nephrotoxicity through ROS-dependent pathways of mitochondrial dynamics in PK15 cells

2,2',4,4'-tetrabromodiphenyl ether (BDE-47)-induced nephrotoxicity is closely associated with oxidative stresses and mitochondrial abnormalities. Mitochondrial fusion and fission dynamics are crucial for maintaining mitochondrial and cellular physiological homeostasis. However, the detailed mechanisms through which BDE-47 disrupts this dynamic and contributes to renal injuries are still not fully understood. The porcine kidney-15 (PK15) cell line, a well-defined in vitro animal renal toxicological model, was exposed to BDE-47 with concentrations of 12.5, 25, 50, and 100 μM, respectively. Cell viability, the levels of reactive oxygen species (ROS) and adenosine triphosphate (ATP), the mitochondrial membrane potential (MMP), and the expression levels of key mitochondrial fusion and fission proteins were assessed. BDE-47 reduced cell viability and disrupted mitochondrial dynamics by inhibiting mitochondrial fusion and fission simultaneously, leading to MMP decreases, ROS overgeneration, ATP depletion, and cellular disintegration in a dose-dependent manner. Additionally, the mitochondrial division inhibitor (Mdivi-1) with the concentration of 20 μM observed to restore the downregulation of mitochondrial fusion and fission proteins, alleviate damages in mitochondrial morphology and functionality, correct ROS overproduction, and enable cell survival. The antioxidant N-acety-L-cysteine (NAC) with the concentration of 1 mM also simultaneously reversed the imbalance of mitochondrial dynamics, decreased ROS production, and restored mitochondrial morphology in PK15 cells exposed to BDE-47. Our data provide new insights indicating that BDE-47 disrupts mitochondrial fusion/fission dynamics to induce mitochondrial abnormalities, triggering oxidative stresses and thus contributing to PK15 cell dysfunction. ROS-dependent pathways in mitochondrial dynamics may provide a new avenue for developing effective strategies to protect cells against BDE-47-induced nephrotoxicity.

Insights into the metabolic mechanism of PBDEs catalyzed by cytochrome P450 enzyme 3A4: A QM/MM study

Elucidating the metabolic mechanism and the derivatives of polybrominated diphenyl ethers (PBDEs) is significant to risk assessment. This study delineated the metabolic mechanism of 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) catalyzed by P450 enzymes using a combination of molecular dynamic (MD), quantum mechanics/molecular mechanics (QM/MM) and density functional theory (DFT). The calculation results reveal that the electrophilic addition is the main pathway for the biotransformation of BDE-47 catalyzed by P450 enzymes. 6-hydroxy-2,2',4,4'-tetrabromodiphenyl ether (6-OH-BDE-47) is a more kinetically preferable product than 5-hydroxy-2,2',4,4'-tetrabromodiphenyl ether (5-OH-BDE-47). Electrophilic addition reaction can lead to the formation of polybrominated dibenzo-p-dioxins and dibenzofurans (PBDD/Fs). The ecotoxicity assessment indicates that the final products of BDE-47 are still toxic to aquatic organisms, but the solubility increase of the hydroxylated products can accelerate their excretion from the body. We expect that the established metabolic mechanism and the derivatives will be used to predict the biotransformation of other PBDE congeners catalyzed by P450 enzymes in human livers.

Previously identified and unidentified polybrominated biphenyl congeners in serum from people living in an electronic waste dismantling area in China

The effects of polybrominated biphenyls (PBBs) on human health have previously attracted much attention, but recent studies of PBBs have been focused on BB-153 and a few other congeners. PBB concentrations in serum samples from residents of an area containing an electronic waste dismantling site were determined in this study. The total PBB concentrations (i.e., the sums of the concentrations of the 35 PBB congeners) were 229-1360 ng/g lipid. The BB-153 concentrations were markedly higher in the samples from people living in the electronic waste dismantling area than in samples from people living in a nearby control area. BB-153 was found in all of the samples from the study exposure area but the concentrations were relatively low (0.07-4.70 ng/g lipid). High BB-1 concentrations were found for the first time in serum from people living in both the electronic waste dismantling and control areas. The BB-1 concentrations were 211-1280 ng/g lipid. The retention times of the 35 PBB standards and PCBs (polychlorinated biphenyls) with similar structures were used to predict the retention times of unidentified PBB congeners to allow the PBB distributions in the serum samples to be identified. A total of 26 previously unidentified PBB congeners were identified in the human serum samples. BB-5, BB-35, BB-79, and BB-109 were found in >50% of the samples. The PBB patterns in the serum samples were different from the patterns previously found in serum after a PBB contamination incident in 1973, so the health risks currently posed by PBBs are worth studying.

Perspective on prenatal polychlorinated biphenyl exposure and the development of the progeny nervous system (Review)

The developmental origins of health and disease concept illustrates that exposure in early life to various factors may affect the offspring's long-term susceptibility to disease. During development, the nervous system is sensitive and vulnerable to the environmental insults. Polychlorinated biphenyls (PCBs), which are divided into dioxin-like (DL-PCBs) and non-dioxin-like PCBs (NDL-PCBs), are synthetic persistent environmental endocrine-disrupting chemicals. The toxicological mechanisms of DL-PCBs have been associated with the activation of the aryl hydrocarbon receptor and NDL-PCBs have been associated with ryanodine receptor-mediated calcium ion channels, which affect neuronal migration, promote dendritic growth and alter neuronal connectivity. In addition, PCB accumulation in the placenta destroys the fetal placental unit and affects endocrine function, particularly thyroid hormones and the dopaminergic system, leading to neuroendocrine disorders. However, epidemiological investigations have not achieved a consistent result in different study cohorts. The present review summarizes the epidemiological differences and possible mechanisms of the effects of intrauterine PCB exposure on neurological development.

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.

Genome-wide DNA methylation differences and polychlorinated biphenyl (PCB) exposure in a US population

Exposure to polychlorinated biphenyls (PCBs), an endocrine-disrupting compound, is ubiquitous despite decades-old bans on the manufacture and use of PCBs. Increased exposure to PCBs is associated with adverse health consequences throughout life, including type 2 diabetes and cancer. PCB exposure is also associated with alterations in epigenetic marks and gene transcription, which could lead to adverse health outcomes, but many of these are population-specific. To further investigate the association between PCB and epigenetic marks, DNA methylation was measured at 787,684 CpG sites in 641 peripheral blood samples from the Michigan Polybrominated Biphenyl (PBB) Registry. 1345 CpGs were associated with increased total PCB level after controlling for age, sex, and 24 surrogate variables (FDR < 0.05). These CpGs were enriched in active promoter and transcription associated regions (p < 0.05), and in regions around the binding sites for transcription factors involved in xenobiotic metabolism and immune function (FDR < 0.05). PCB exposure also associated with proportions of CD4T, NK, and granulocyte cell types, and with the neutrophil to lymphocyte ratio (NLR) (p < 0.05), and the estimated effect sizes of PCB on the epigenome were correlated with the effect sizes previously reported in an epigenome-wide study of C-reactive protein (r = 0.29; p = 2.22e-5), supporting previous studies on the association between PCB and immune dysfunction. These results indicate that PCB exposure is associated with differences in epigenetic marks in active regions of the genome, and future work should investigate whether these may mediate the association between PCB and health consequences.

Establishment of a CoMFA Model Based on the Combined Activity of Bioconcentration, Long-Range Transport, and Highest Infrared Signal Intensity and Molecular Design of Environmentally Friendly PBB Derivatives

In the current study, a comparative molecular field analysis (CoMFA) model with the combined activity of polybrominated biphenyls (PBBs) bioconcentration, long-range transport, and the highest infrared signal intensity (weight ratio of 5:4:1) was constructed based on the threshold method and was further evaluated and analyzed. PBB-153 derivatives with improved combined activity values of bioconcentration, long-range transport, and the highest infrared signals intensity were designed based on contour maps of the CoMFA model. The environmental stability and functionality of the derivatives were also evaluated. The constructed model showed good prediction ability, fitting ability, stability, and external prediction ability. The contribution rates of electrostatic and steric fields to the combined activity of PBBs were 53.4% and 46.6%, respectively. Four PBB-153 derivatives with significantly improved bioconcentration, long-range transport and the highest infrared signal intensity (the combined activity value of these three parameters decreased) were screened with good environmental stability and functionality. Results validated the accuracy and reliability, and ability of the generated model to realize the simultaneous modification of the three activities of the target molecule. The binding ability of the designed derivatives to food chain biodegradation enzymes increased, thereby verifying the improvement in the bioconcentration. The half-lives of the derivatives in air and their ability to be absorbed by the plants significantly improved compared to the target molecule, further showing that the long-range transport of derivatives was reduced. In addition, the introduction of the –NO group caused the N =O stretching vibration of the derivatives to increase the infrared signal intensity. The present model provides a theoretical design method for the molecular modification of environmentally friendly PBBs.

Serum levels of novel brominated flame retardants (NBFRs) in residents of a major BFR-producing region: Occurrence, impact factors and the relationship to thyroid and liver function

Five currently used novel brominated flame retardants (NBFRs) were determined in 172 serum samples collected from nonoccupational residents of a major BFR-producing region. All the 5 NBFRs presented high detection frequencies (DFs, >90%), and decabromodiphenyl ethane (DBDPE), a substitute of decabrominated diphenyl ethers (deca-BDE), was the most abundant NBFR. The levels of DBDPE were from <LOD to 1590 ng/g lw, with a median level of 32.5 ng/g lw. The median levels of other NBFRs were from 0.134 to 2.87 ng/g lw, which were at least 10 times lower than that of DBDPE. Moreover, a comparison to other studies showed that our results were significantly higher than studies conducted in background population. The levels of some NBFRs adjusted by serum lipid showed negative and significant correlation with BMI, whereas the difference disappeared when NBFRs levels were calculated based on serum volume. Certain NBFRs in female showed significantly higher concentrations than those in male. No significant effect of age, smoking habit, education level and children birth (in female) on serum NBFR levels was observed. The relationship between the serum levels of NBFRs and a series of thyroid/liver injury biomarkers was further analyzed to evaluate the health effects of these NBFRs to human being. Results showed that a 10-fold increment in the serum DBDPE level was associated with decreased total triiodothyronine (TT3) level (-0.037 nmol/L) [95% CI: -0.070, -0.003]， whereas serum pentabromoethylbenzene (PBEB) level was associated with increased total triiodothyronine (TT3) level (0.031 nmol/L) [95% CI: 0.001, 0.060]. For liver indicators, a 10-fold increment in the serum level of PBT was associated with decreased Ln aspartate aminotransferase/alanine aminotransferase (AST/ALT) level (-0.068) [95% CI: -0.129, -0.007]. A 10-fold increment in the serum level of BTBPE was associated with increased TBIL level (0.869 μmol/L) [95% CI: 0.175, 1.564], direct bilirubin (DBIL) level (0.231 μmol/L) [95% CI: 0.075, 0.388] and IDBIL level (0.638 μmol/L) [95% CI: 0.091, 1.185]. Our findings indicate that BFR production is posing heavy BFR contamination to surrounding environment and human being, and which might relate to thyroid disruption and liver injury.

The association of liver function biomarkers with internal exposure of short- and medium-chain chlorinated paraffins in residents from Jinan, China

Chlorinated paraffins (CPs) are pervasive environmental pollutants which have been reported to be hepatotoxic by laboratory cell and animal studies. However, the related epidemiological reports on their hepatotoxic effects to humans are sparse. In this study, we evaluated the associations between six liver enzymes and serum short-chain CP (SCCP) or medium-chain CP (MCCP) concentrations of 197 residents in Jinan, China. Serum S/MCCPs were detected by quadrupole time-of-flight high-resolution mass spectrometry coupled with atmospheric pressure chemical ionization source (APCI-QTOF-HRMS), and quantified by pattern deconvolution method. The associations between total serum S/MCCP concentrations (ΣS/MCCPs) and continuous liver enzyme levels were assessed by linear regression. Odds ratios (ORs) for the effects of serum ΣS/MCCPs concentrations on liver function biomarkers dichotomized by clinical reference intervals were predicted by logistic regression, either treating ΣS/MCCPs as continuous or categorical dependents. After multivariable adjustment, linear regression results illustrated that 1-ln unit increase in serum ΣSCCPs was negatively associated with male PA levels [-6.08, 95% confidence interval (CI): -11.90, -3.25, p < 0.05], positively associated with male TB levels (1.80, 95% CI: 0.28, 3.31, p < 0.05), and positively associated with female AST levels (1.39, 95% CI: 0.07, 2.70, p < 0.05). One-ln unit increase in serum ΣMCCPs was negatively associated male PA levels (-7.56, 95% CI: -17.15, -4.03, p < 0.05). Logistic regression results suggested that male serum ΣSCCPs were associated with increased prevalence of abnormal PA (OR = 1.47 per 1 ln-unit increase, CI = 1.18, 1.82) and TB (OR = 1.75, 95% CI = 1.12, 2.76) levels, and male serum ΣMCCPs were significantly associated with increased prevalence of abnormal PA (OR = 1.43, 95% CI = 1.03, 1.97) levels. In addition, male participants with concentrations above the median ΣS/MCCPs were associated with increased risk for abnormal PA levels [SCCPs, 2.11-fold (95% CI = 1.15, 3.87); MCCPs, 1.94-fold (95% CI = 1.24, 3.03)]. Male participants with concentrations above the median ΣSCCPs were also associated with increased risk for abnormal TB levels (OR = 1.75, 95% CI = 1.12, 2.76). Conclusively, our results revealed that CP internal exposure was associated with disturbed liver biomarker levels, suggesting the hepatotoxicity of both SCCPs and MCCPs to humans.

BDE-47 induced apoptosis in zebrafish embryos through mitochondrial ROS-mediated JNK signaling

2,2,4,4-tetrabromodiphenyl ether (BDE-47) has received considerable attention because of its high detection level in biological samples and potential developmental toxicity. Here, using zebrafish (Danio rerio) as the experimental animal, we investigated developmental effects of BDE-47 and explored the potential mechanism. Zebrafish embryos at 4 h post-fertilization (hpf) were exposed to 0.312, 0.625 and 1.25 mg/L BDE-47 to 74-120 hpf. We found that BDE-47 instigated a dose-related developmental toxicity, evidenced by reduced embryonic survival and hatching rate, shortened body length and increased aberration rate. Meanwhile, higher doses of BDE-47 reduced mitochondrial membrane potential and ATP production but increased apoptosis in zebrafish embryos. Expression of genes involved in mitochondrial oxidative phosphorylation (OXPHOS) (ndufb8, sdha, uqcrc1, cox5ab and atp5fal) were negatively related to BDE-47 doses in zebrafish embryos. Moreover, exposure to BDE-47 at 0.625 or 1.25 mg/L impaired mitochondrial biogenesis and mitochondrial dynamics. Our data further showed that BDE- 47 exposure induced excessive reactive oxygen species (ROS) and oxidative stress, which was accompanied by the activation of c-Jun N-terminal Kinase (JNK). Antioxidant NAC and JNK inhibition could mitigate apoptosis in embryos and improve embryonic development in BDE-47-treated zebrafish, suggesting the involvement of ROS/JNK pathway in embryonic developmental changes induced by BDE-47. Altogether, our data suggest here that developmental toxicity of BDE-47 may be associated with mitochondrial ROS-mediated JNK signaling in zebrafish embryo.

Detrimental effects of flame retardant, PBB153, exposure on sperm and future generations

In 1973, the Velsicol Chemical Company, which manufactured FireMaster, a brominated flame retardant, and NutriMaster, a nutritional supplement, mistakenly shipped hundreds of pounds of FireMaster to grain mills around Michigan where it was incorporated into animal feed and then into the food chain across the state. An estimated 6.5 million Michigan residents consumed polybrominated biphenyl (PBB)-laced animal products leading to one of the largest agricultural accidents in U.S. history. To date, there have been no studies investigating the effects of PBB on epigenetic regulation in sperm, which could explain some of the endocrine-related health effects observed among children of PBB-exposed parents. Fusing epidemiological approaches with a novel in vitro model of human spermatogenesis, we demonstrate that exposure to PBB153, the primary component of FireMaster, alters the epigenome in human spermatogenic cells. Using our novel stem cell-based spermatogenesis model, we show that PBB153 exposure decreases DNA methylation at regulatory elements controlling imprinted genes. Furthermore, PBB153 affects DNA methylation by reducing de novo DNA methyltransferase activity at increasing PBB153 concentrations as well as reducing maintenance DNA methyltransferase activity at the lowest tested PBB153 concentration. Additionally, PBB153 exposure alters the expression of genes critical to proper human development. Taken together, these results suggest that PBB153 exposure alters the epigenome by disrupting methyltransferase activity leading to defects in imprint establishment causing altered gene expression, which could contribute to health concerns in the children of men exposed to PBB153. While this chemical is toxic to those directly exposed, the results from this study indicate that the epigenetic repercussions may be detrimental to future generations. Above all, this model may be expanded to model a multitude of environmental exposures to elucidate the effect of various chemicals on germline epigenetics and how paternal exposure may impact the health of future generations.