Municipal wastewater affects adipose deposition in male mice and increases 3T3-L1 cell differentiation

Integrated toxicity of secondary, tertiary, wetland effluents on human stem cells triggered by ERα and PPARγ agonists

Residual pollutants in discharged and reused water pose both direct and indirect human exposure. However, health effects caused by whole effluent remain largely unknown due to the lack of human relevant model for toxicity test. Effluents from four secondary wastewater treatment plants (SWTPs), a tertiary wastewater treatment plant (TWTP) and a constructed wetland (CW) were evaluated for the integrated toxicity of the organic extractions. Multiple-endpoint human mesenchymal stem cells (MSCs) assay was used as an in vitro model relevant to human health. The effluents caused cytotoxicity, oxidative stress and genotoxicity in MSCs. The osteogenic and neurogenic differentiation were inhibited and the adipogenic differentiation were stimulated by some of the effluent extractions. The SWTP, TWTP and CW treatments reduced integrated biomarker response (IBR) by 26.3 %, 17.5 % and 33.3 % respectively, where the IBR values of final CW (8.3) and TWTP (8.2) effluents were relatively lower than SWTPs (9.1). Among multiple biomarkers, the inhibition of osteogenesis was the least reduced by wastewater treatment. Besides, ozone disinfection in tertiary treatment increased cytotoxicity and differentiation effects suggesting the generation of toxic products. The mRNA expressions of estrogen receptor alpha (ERα) and peroxisome proliferator-activated receptor gamma (PPARγ) were significantly upregulated by effluents. The inhibitory effects of effluents on neural differentiation were mitigated after antagonizing ERα and PPARγ in the cells. It is suggested that ERα and PPARγ agonists in effluents were largely accountable for the impairment of stem cell differentiation. Besides, the concentrations of n-C29H60, o-cresol, fluorene and phenanthrene in the effluents were significantly correlated with the intergrated stem cell toxicity. The present study provided toxicological evidence for the relation between water contamination and human health, with an insight into the key toxicity drivers. The necessity for deep water treatment and the potential means were suggested for improving water quality.

Emerging regulatory roles of noncoding RNAs induced by bisphenol A (BPA) and its alternatives in human diseases

Bisphenols (BPs), including BPA, BPF, BPS, and BPAF, are synthetic phenolic organic compounds and endocrine-disrupting chemicals. These organics have been broadly utilized to produce epoxy resins, polycarbonate plastics, and other products. Mounting evidence has shown that BPs, especially BPA, may enter into the human body and participate in the development of human diseases mediated by nuclear hormone receptors. Moreover, BPA may negatively affect human health at the epigenetic level through processes such as DNA methylation and histone acetylation. Recent studies have demonstrated that, as part of epigenetics, noncoding RNAs (ncRNAs), including microRNAs (miRNAs), long noncoding RNAs (lncRNAs), circular RNAs (circRNAs), and small nucleolar RNAs (snoRNAs), have vital impacts on BP-related diseases, such as reproductive system diseases, nervous system diseases, digestive system diseases, endocrine system diseases, and other diseases. Moreover, based on the bioinformatic analysis, changes in ncRNAs may be relevant to normal activities and functions and BP-induced diseases. Thus, we conducted a meta-analysis to identify more promising ncRNAs as biomarkers and therapeutic targets for BP exposure and relevant human diseases. In this review, we summarize the regulatory functions of ncRNAs induced by BPs in human diseases and latent molecular mechanisms, as well as identify prospective biomarkers and therapeutic targets for BP exposure and upper diseases.

Exploring novel insights into the molecular mechanisms underlying Bisphenol A-induced toxicity: A persistent threat to human health

Bisphenol A (BPA) is a ubiquitous industrial chemical used in the production of polycarbonate plastics and epoxy resins, found in numerous consumer products. Despite its widespread use, its potential adverse health effects have raised significant concerns. This review explores the molecular mechanisms and evidence-based literature underlying BPA-induced toxicities and its implications for human health. BPA is an endocrine-disrupting chemical (EDC) which exhibits carcinogenic properties by influencing various receptors, such as ER, AhR, PPARs, LXRs, and RARs. It induces oxidative stress and contributes to cellular dysfunction, inflammation, and DNA damage, ultimately leading to various toxicities including but not limited to reproductive, cardiotoxicity, neurotoxicity, and endocrine toxicity. Moreover, BPA can modify DNA methylation patterns, histone modifications, and non-coding RNA expression, leading to epigenetic changes and contribute to carcinogenesis. Overall, understanding molecular mechanisms of BPA-induced toxicity is crucial for developing effective strategies and policies to mitigate its adverse effects on human health.

Toxicity removal from contaminated water by constructed wetlands assessed using multiple biomarkers in human stem cell assays

Constructed wetlands (CWs) have been developed rapidly as a sustainable water treatment technique. However, the capability of CWs for remediating the contaminated water based on toxicity assessment remains largely unknown. Four surface flow CWs and two integrated surface-subsurface flow CWs, from five cities in central and eastern region of China were evaluated, concerning the adverse effects of effluents and the toxicity reduction efficiency. Human bone marrow mesenchymal stem cells (hBMSCs) were employed as a human relevant in vitro model. The influent extractions caused cytotoxicity in a dose-dependent manner. The non-cytotoxic dilutions of the influents enhanced the genotoxicity marker γ-H2AX and reactive oxygen species levels. In addition, the influent repressed the osteogenic and neurogenic differentiation, and stimulated the adipogenic differentiation. Cytotoxicity of the contaminated water was reduced by 54 %-86 % after treatment with CWs. CWs were effective to remove part of the sub-lethal effects, with lower reduction than cytotoxicity. The integrated biomarker response (IBR) value of the effluents from the six CWs is lower than that of four secondary and one tertiary wastewater treatment plants. The IBR of the six CWs influents were in the range of 8.6-10.6, with a reduction of 15-50 % after the pollution restoration in CWs. The two integrated surface-subsurface flow CWs achieved higher IBR removal than the four surface flow CWs, possibly due to improved treatment effects by the combined systems. Cytotoxic and genotoxic effects of polar fractions in the CW effluents were stronger than the medium-polar and the non-polar fractions. Besides, PPARγ agonists present in the effluents played crucial roles and ERα agonists may make modest contributions. The present study enhances understanding of the role of CWs in achieving safe wastewater reclamation and provides evidence for further improving toxicity reduction in CWs performance.

Excess feeding increases adipogenesis but lowers leptin transcript abundance in zebrafish larvae

Although fish exposed to municipal wastewater effluents (MWWE) show higher lipid accumulation, whether this is due to adipogenesis is unclear. The objective here was to identify molecular markers of adipogenesis in zebrafish (Danio rerio) larvae for use as high throughput screening tools for environmental contaminants, including obesogens in MWWE. Zebrafish larvae were fed a commercial diet at a maintenance level (5 % body mass) or in excess (25 or 50 % body mass) from day 6 to 30 days post-fertilization (dpf) to stimulate adipogenesis. We monitored fat accumulation and markers of lipid metabolism, including peroxisome proliferator-activated receptor γ (ppar γ), fatty acid synthase (fas), ELOVL fatty acid elongase 2 (elovl2), diacylglycerol O-acyltransferase 2 (dgat2), leptin (lepa and lepb), leptin receptor (lepr), and lipoprotein lipase (lpl). Excess feeding led to a higher growth rate, protein content and an increase in igf1 transcript abundance. Also, these larvae had higher triglyceride levels and accumulated lipids droplets in the abdominal cavity and viscera. The molecular markers of adipogenesis, including fas, elovl2, and dgat2, were upregulated, while the transcript abundance of lpl, a lipolytic gene, was transiently lower due to excess feeding. The increased adiposity seen at 30 dpf due to excess feeding coincided with a lower lep but not lepr transcript abundance in zebrafish. Our results demonstrate that excess feeding alters the developmental programming of key genes involved in lipid homeostasis, leading to excess lipid accumulation in zebrafish larvae. Overall, fas, elovl2, lpl, and dgat2, but not lep or ppar γ, have the potential to be biomarkers of adipogenesis in zebrafish larvae.

Bisphenol A (BPA) and Cardiovascular or Cardiometabolic Diseases

Bisphenol A (BPA; 4,4'-isopropylidenediphenol) is a well-known endocrine disruptor. Most human exposure to BPA occurs through the consumption of BPA-contaminated foods. Cardiovascular or cardiometabolic diseases such as diabetes, obesity, hypertension, acute kidney disease, chronic kidney disease, and heart failure are the leading causes of death worldwide. Positive associations have been reported between blood or urinary BPA levels and cardiovascular or cardiometabolic diseases. BPA also induces disorders or dysfunctions in the tissues associated with these diseases through various cell signaling pathways. This review highlights the literature elucidating the relationship between BPA and various cardiovascular or cardiometabolic diseases and the potential mechanisms underlying BPA-mediated disorders or dysfunctions in tissues such as blood vessels, skeletal muscle, adipose tissue, liver, pancreas, kidney, and heart that are associated with these diseases.

In vitro to in vivo extrapolation for predicting human equivalent dose of phenolic endocrine disrupting chemicals: PBTK model development, biological pathways, outcomes and performance

In vitro to in vivo (IVIVE) leverages in vitro high-throughput biological responses to predict the corresponding in vivo exposures and further estimate the human safe dose. However, for phenolic endocrine disrupting chemicals (EDCs) linked with complicated biological pathways and adverse outcomes (AO), such as bisphenol A (BPA) and 4-nonylphenol (4-NP), plausible estimation of human equivalent doses (HED) by IVIVE approaches considering various biological pathways and endpoints is still challenging. To explore the capabilities and limitations of IVIVE, this study conducted physiologically based toxicokinetic (PBTK)-IVIVE approaches to derive pathway-specific HEDs using BPA and 4-NP as examples. In vitro HEDs of BPA and 4-NP varied in different adverse outcomes, pathways, and testing endpoints and ranged from 0.0013 to 1.0986 mg/kg bw/day and 0.0551 to 1.7483 mg/kg bw/day, respectively. In vitro HEDs associated with reproductive AOs initiated by PPARα activation and ER agonism were the most sensitive. Model verification suggested the potential of using effective in vitro data to determine reasonable approximation of in vivo HEDs for the same AO (fold differences of most AOs ranged in 0.14-2.74 and better predictions for apical endpoints). Furthermore, system-specific parameters of cardiac output and its fraction, body weight, as well as chemical-specific parameters of partition coefficient and liver metabolic were most sensitive for the PBTK simulations. The results indicated that the application of fit for-purpose PBTK-IVIVE approach could provide credible pathway-specific HEDs and contribute to high throughput prioritization of chemicals in a more realistic scenario.

Re-evaluation of the risks to public health related to the presence of bisphenol A (BPA) in foodstuffs

In 2015, EFSA established a temporary tolerable daily intake (t-TDI) for BPA of 4 μg/kg body weight (bw) per day. In 2016, the European Commission mandated EFSA to re-evaluate the risks to public health from the presence of BPA in foodstuffs and to establish a tolerable daily intake (TDI). For this re-evaluation, a pre-established protocol was used that had undergone public consultation. The CEP Panel concluded that it is Unlikely to Very Unlikely that BPA presents a genotoxic hazard through a direct mechanism. Taking into consideration the evidence from animal data and support from human observational studies, the immune system was identified as most sensitive to BPA exposure. An effect on Th17 cells in mice was identified as the critical effect; these cells are pivotal in cellular immune mechanisms and involved in the development of inflammatory conditions, including autoimmunity and lung inflammation. A reference point (RP) of 8.2 ng/kg bw per day, expressed as human equivalent dose, was identified for the critical effect. Uncertainty analysis assessed a probability of 57-73% that the lowest estimated Benchmark Dose (BMD) for other health effects was below the RP based on Th17 cells. In view of this, the CEP Panel judged that an additional uncertainty factor (UF) of 2 was needed for establishing the TDI. Applying an overall UF of 50 to the RP, a TDI of 0.2 ng BPA/kg bw per day was established. Comparison of this TDI with the dietary exposure estimates from the 2015 EFSA opinion showed that both the mean and the 95th percentile dietary exposures in all age groups exceeded the TDI by two to three orders of magnitude. Even considering the uncertainty in the exposure assessment, the exceedance being so large, the CEP Panel concluded that there is a health concern from dietary BPA exposure.

The hazardous threat of Bisphenol A: Toxicity, detection and remediation

Bisphenol A (or BPA) is a toxic endocrine disrupting chemical that is released into the environment through modern manufacturing practices. BPA can disrupt the production, function and activity of endogenous hormones causing irregularity in the hypothalamus-pituitary-gonadal glands and also the pituitary-adrenal function. BPA has immuno-suppression activity and can downregulate T cells and antioxidant genes. The genotoxicity and cytotoxicity of BPA is paramount and therefore, there is an immediate need to properly detect and remediate its influence. In this review, we discuss the toxic effects of BPA on different metabolic systems in the human body, followed by its mechanism of action. Various novel detection techniques (LC-MS, GC-MS, capillary electrophoresis, immunoassay and sensors) involving a pretreatment step (liquid-liquid microextraction and molecularly imprinted solid-phase extraction) have also been detailed. Mechanisms of various remediation strategies, including biodegradation using native enzymes, membrane separation processes, photocatalytic oxidation, use of nanosorbents and thermal degradation has been detailed. An overview of the global regulations pertaining to BPA has been presented. More investigations are required on the efficiency of integrated remediation technologies rather than standalone methods for BPA removal. The effect of processing operations on BPA in food matrices is also warranted to restrict its transport into food products.

The Role of Persistent Organic Pollutants in Obesity: A Review of Laboratory and Epidemiological Studies

Persistent organic pollutants (POPs) are considered as potential obesogens that may affect adipose tissue development and functioning, thus promoting obesity. However, various POPs may have different mechanisms of action. The objective of the present review is to discuss the key mechanisms linking exposure to POPs to adipose tissue dysfunction and obesity. Laboratory data clearly demonstrate that the mechanisms associated with the interference of exposure to POPs with obesity include: (a) dysregulation of adipogenesis regulators (PPARγ and C/EBPα); (b) affinity and binding to nuclear receptors; (c) epigenetic effects; and/or (d) proinflammatory activity. Although in vivo data are generally corroborative of the in vitro results, studies in living organisms have shown that the impact of POPs on adipogenesis is affected by biological factors such as sex, age, and period of exposure. Epidemiological data demonstrate a significant association between exposure to POPs and obesity and obesity-associated metabolic disturbances (e.g., type 2 diabetes mellitus and metabolic syndrome), although the existing data are considered insufficient. In conclusion, both laboratory and epidemiological data underline the significant role of POPs as environmental obesogens. However, further studies are required to better characterize both the mechanisms and the dose/concentration-response effects of exposure to POPs in the development of obesity and other metabolic diseases.

The Impact of Bisphenol A on Thyroid Function in Neonates and Children: A Systematic Review of the Literature

Background: Bisphenol A (BPA) is an endocrine-disrupting chemical widely used in plastic products that may have an adverse effect on several physiologic functions in children. The aim of this systematic review is to summarize the current knowledge of the impact of BPA concentrations on thyroid function in neonates, children, and adolescents. Methods: A systematic search of Medline, Scopus, Clinical Trials.gov, Cochrane Central Register of Controlled Trials CENTRAL, and Google Scholar databases according to PRISMA guidelines was performed. Only case–control, cross-sectional, and cohort studies that assessed the relationship between Bisphenol A and thyroid function in neonates and children aged <18 years were included. Initially, 102 articles were assessed, which were restricted to 73 articles after exclusion of duplicates. A total of 73 articles were assessed by two independent researchers based on the title/abstract and the predetermined inclusion and exclusion criteria. According to the eligibility criteria, 18 full-text articles were selected for further assessment. Finally, 12 full-text articles were included in the present systematic review. Results: The presented studies offer data that suggest a negative correlation of BPA concentrations with TSH in children, a gender-specific manner of action, and a potential effect on proper neurodevelopment. However, the results are inconclusive with respect to specific thyroid hormone concentrations and the effect on thyroid autoimmunity. Conclusion: The potential negative effect of BPA in the developing thyroid gland of children that may affect proper neurodevelopment, suggesting the need to focus future research on designing studies that elucidate the underlying mechanisms and the effects of BPA in thyroid function in early life.

Wild longnose dace downstream of wastewater treatment plants display an obese phenotype

Wild fish living downstream of wastewater treatment plants (WWTPs) often have increased body condition factors or body mass indices compared to upstream fish. This observation has been largely attributed to increased nutrient loading and food availability around wastewater effluent outflows. While a higher condition factor in fish is generally considered a predictor of healthy ecosystems, the metabolic status and capacity of the animals downstream of WWTPs may be a better predictor of fitness and potential population level effects. To address this, we sampled wild longnose dace (Rhinichthys cataractae), a native species in North American waterways, from sites upstream and downstream of WWTPs. Downstream fish had higher body mass indices, which corresponded with higher nutrient (lipid, protein, and glycogen) storage in somatic tissues compared to upstream fish. Liver transcriptome analysis revealed metabolic reprogramming favoring lipid synthesis, including higher hepatic triglyceride levels and transcript abundance of targeted lipogenic genes. This suggests that effluent exposure-mediated obesity in dace is a result of changes at the transcriptional level. To determine potential ecological consequences, we subjected these fish to an acute stressor in situ to determine their stress performance. Downstream fish failed to mobilize metabolites post-stress, and showed a reduction in liver aerobic and anaerobic metabolic capacity. Taken together, fish living downstream of WWTPs exhibit a greater lipid accumulation that results in metabolic disruption and may compromise the ability of these fish to cope with subsequent environmental and/or anthropogenic stressors.

Endocrine disrupting chemicals and bone

Endocrine-disrupting chemicals (EDCs) are defined as chemicals that interfere with the function of the endocrine system. EDCs exert their hormonal effects through several mechanisms; modulating hormone receptors or changing metabolism of different hormones. EDCs also influence multiple signalling pathways while effecting the hormonal systems and possess complex dose-response curves. EDCs can exert deleterious effects on bone tissue through changing bone modelling and remodelling via altering bone paracrine hormone synthesis, the release of systemic hormones, cytokines, chemokines and growth factors, and effecting stem cell fate, as well as bone marrow mesenchymal stem cell differentiation. Evidence is accumulating of the bone disrupting effect of different groups of EDCs, such as; the perfluoroalkyl substances, the phthalate esters, the bisphenol A, the organotin compounds, the alkylphenols and the dioxin and dioxin-like compounds. This review highlights the recent discoveries of the effects of commonly found environmental chemicals on bone from basic molecular findings to clinical implications.

The new kids on the block: Emerging obesogens

The current obesity epidemic is calling for action in the determination of contributing factors. Although social and life-style factors have been traditionally associated with metabolic disruption, a subset of endocrine-disrupting chemicals (EDCs), called obesogens are garnering increasing attention for their ability to promote adipose tissue differentiation and accumulation. For some chemicals, such as tributyltin, there is conclusive evidence regarding their ability to promote adipogenesis and their mechanism of action. In recent years, the list of chemicals that exert obesogenic potential is increasing. In this chapter, we review current knowledge of the most recent developments in the field of emerging obesogens with a specific focus on food additives, surfactants, and sunscreens, for which the mechanism of action remains unclear. We also review new evidence relative to the obesogenic potential of environmentally relevant chemical mixtures and point to potential therapeutic approaches to minimize the detrimental effects of obesogens. We conclude by discussing the available tools to investigate new obesogenic chemicals, strategies to maximize reproducibility in adipogenic studies, and future directions that will help propel the field forward.

Endocrine disruptor global policy

Over the past several decades, scientific consensus has grown around the concept and evidence for human health impacts from exposure to endocrine disrupting chemicals (EDCs). A series of publications have now demonstrated considerable economic costs of EDC exposure-induced adverse health outcomes. This research has suggested economic burdens in the hundreds of billions, even considering only a small subset of EDCs and health. As of yet, regulatory efforts and policies to protect and decrease human exposure to most EDCs have been insufficient and have not kept pace with the science. Given the overwhelming scientific evidence, referenced throughout this collection, as well as the economic costs of inaction, described here, regulations are clearly needed. The EU and some other countries have taken promising steps towards protective regulation of EDCs, though the response of the US and many other countries has been limited or altogether lacking. Regulatory bodies that have and continue to apply risk-based approaches to regulating EDCs have also failed to consider the complete economic impacts of EDC-related health impacts. In this chapter, we will discuss broad strategies taken to regulate EDCs, examine the approaches currently taken to regulate EDCs in a global context (discussing the strengths and weaknesses of these regulations), discuss the economic costs of EDC exposures (detailing where consideration of health and economic costs could improve regulations), and discuss next steps and novel approaches to adapting existing regulatory frameworks to this class of chemicals.

Characterization of adipogenic, PPARγ, and TRβ activities in house dust extracts and their associations with organic contaminants

In this study, we sought to expand our previous research on associations between bioactivities in dust and associated organic contaminants. Dust samples were collected from central NC homes (n = 188), solvent extracted, and split into two fractions, one for analysis using three different bioassays (nuclear receptor activation/inhibition and adipocyte development) and one for mass spectrometry (targeted measurement of 124 organic contaminants, including flame retardants, polychlorinated biphenyls, perfluoroalkyl substances, pesticides, phthalates, and polycyclic aromatic hydrocarbons). Approximately 80% of dust extracts exhibited significant adipogenic activity at concentrations that are comparable to estimated exposure for children and adults (e.g. ~20 μg/well dust) via either triglyceride accumulation (65%) and/or pre-adipocyte proliferation (50%). Approximately 76% of samples antagonized thyroid receptor beta (TRβ), and 21% activated peroxisome proliferator activated receptor gamma (PPARγ). Triglyceride accumulation was significantly correlated with TRβ antagonism. Sixty-five contaminants were detected in at least 75% of samples; of these, 26 were correlated with adipogenic activity and ten with TRβ antagonism. Regression models were used to evaluate associations of individual contaminants with adipogenic and TRβ bioactivities, and many individual contaminants were significantly associated. An exploratory g-computation model was used to evaluate the effect of mixtures. Contaminant mixtures were positively associated with triglyceride accumulation, and the magnitude of effect was larger than for any individually measured chemical. For each quartile increase in mixture exposure, triglyceride accumulation increased by 212% (RR = 3.12 and 95% confidence interval: 1.58, 6.17). These results suggest that complex mixtures of chemicals present in house dust may induce adipogenic activity in vitro at environmental concentrations and warrants further research.

Urinary bisphenol A concentrations and the risk of obesity in Korean adults

This study was aimed to evaluate the association between urinary bisphenol A (BPA) levels and risk of obesity in Korean adults. We analyzed data from the Korean National Environmental Health Survey (KoNEHS) Cycle 2 (2012–2014) and Cycle 3 (2015–2017). A total of 10,021 participants aged ≥ 19 years were included. Urine dilution was corrected by the covariate-adjusted standardization (CAS) method. We performed meta-analysis, logistic regression analysis by matching all covariates with a 1:1 propensity score, and a 4-knot restricted cubic spline plot model to calculate the odds ratios (ORs) for obesity according to natural log-transformed BPA levels. Mean urinary BPA concentration was 1.12 µg/L in KoNEHS Cycle 2 and 1.32 µg/L in Cycle 3. BPA levels were significantly higher among obese adults than among non-obese adults in both KoNEHS Cycles 2 and 3. In pooled data of KoNEHS Cycles 2 and 3, BPA showed significant positive associations with ORs for obesity in both sexes, which were more prominent in females (linear) than in males (non-linear). These associations were confirmed in spline analyses. CAS-applied BPA concentrations were positively associated with obesity in nationwide representative samples of Korean adults. Further studies are warranted to confirm and elucidate the underlying mechanism.

Potential Mechanisms of Bisphenol A (BPA) Contributing to Human Disease

Bisphenol A (BPA) is an organic synthetic compound serving as a monomer to produce polycarbonate plastic, widely used in the packaging for food and drinks, medical devices, thermal paper, and dental materials. BPA can contaminate food, beverage, air, and soil. It accumulates in several human tissues and organs and is potentially harmful to human health through different molecular mechanisms. Due to its hormone-like properties, BPA may bind to estrogen receptors, thereby affecting both body weight and tumorigenesis. BPA may also affect metabolism and cancer progression, by interacting with GPR30, and may impair male reproductive function, by binding to androgen receptors. Several transcription factors, including PPARγ, C/EBP, Nrf2, HOX, and HAND2, are involved in BPA action on fat and liver homeostasis, the cardiovascular system, and cancer. Finally, epigenetic changes, such as DNA methylation, histones modification, and changes in microRNAs expression contribute to BPA pathological effects. This review aims to provide an extensive and comprehensive analysis of the most recent evidence about the potential mechanisms by which BPA affects human health.

Endocrine-disrupting chemicals: economic, regulatory, and policy implications

Endocrine-disrupting chemicals (EDCs) substantially cost society as a result of increases in disease and disability but-unlike other toxicant classes such as carcinogens-have yet to be codified into regulations as a hazard category. This Series paper examines economic, regulatory, and policy approaches to limit human EDC exposures and describes potential improvements. In the EU, general principles for EDCs call for minimisation of human exposure, identification as substances of very high concern, and ban on use in pesticides. In the USA, screening and testing programmes are focused on oestrogenic EDCs exclusively, and regulation is strictly risk-based. Minimisation of human exposure is unlikely without a clear overarching definition for EDCs and relevant pre-marketing test requirements. We call for a multifaceted international programme (eg, modelled on the International Agency for Research in Cancer) to address the effects of EDCs on human health-an approach that would proactively identify hazards for subsequent regulation.

The adverse health effects of bisphenol A and related toxicity mechanisms

Bisphenol A (BPA) is an industrial component commonly used in synthesis of polycarbonate plastics, epoxy resin and other polymer materials. Due to its mass productions and widespread applications, the presence of BPA is ubiquitous in the environment. BPA can enter the body via different ways such as digestive tract, respiratory tract and dermal tract. As an endocrine disruptor, BPA has estrogen-like and anti-androgen effects causing damages to different tissues and organs, including reproductive system, immune system and neuroendocrine system, etc. Recently, it has been shown that BPA could induce carcinogenesis and mutagenesis in animal models. Here, the underlying mechanisms of BPA-induced multi-organ toxicity were well summarized, involving the receptor pathways, disruption of neuroendocrine system, inhibition of enzymes, modulation of immune and inflammatory responses, as well as genotoxic and epigenetic mechanisms. The aim of this review is to compile the available current research data regarding BPA and provide an overview of the current status of BPA exposure and relevant health effects covering reproductive, developmental, metabolic, immuno, respiratory, hepatic and renal toxicity and carcinogenesis of BPA. This review provides comprehensive data of BPA toxicity on human health and related mechanisms. We also identify any missing data which should be addressed by further studies.

Bisphenol a: A narrative review of prenatal exposure effects on adipogenesis and childhood obesity via peroxisome proliferator-activated receptor gamma

There is significant evidence of globally ubiquitous prenatal exposures to bisphenol A (BPA). Childhood obesity as an epidemic has been a global concern for over a decade. Experimental models and epidemiological evidence suggest that BPA may act as an obesogen during adipogenesis. Results from stem cell models and birth cohort studies support the developmental origins of health and disease theory. While literature reviews have presented a variety of potential mechanisms of BPA action during adipogenesis, there remains no consensus. This review is the first to explore the proliferator-activated receptor gamma (PPARγ) mechanism in detail. This review will also examine the obesogenic effect of prenatal exposure to BPA during critical windows of vulnerability. Although vast experimental literature exists, there is limited epidemiological evidence to support the hypothesis for the obesogenic effect of BPA. The primary goal of this review is to provide researchers with a roadmap of existing research and suggestions for future directions for analyzing the relationship between prenatal BPA exposures and childhood obesity.

Developmental programming: Changes in mediators of insulin sensitivity in prenatal bisphenol A-treated female sheep

Developmental exposure to endocrine disruptor bisphenol A (BPA) is associated with metabolic defects during adulthood. In sheep, prenatal BPA treatment causes insulin resistance (IR) and adipocyte hypertrophy in the female offspring. To determine if changes in insulin sensitivity mediators (increase in inflammation, oxidative stress, and lipotoxicity and/or decrease in adiponectin) and the intracrine steroidal milieu contributes to these metabolic perturbations, metabolic tissues collected from 21-month-old female offspring born to mothers treated with 0, 0.05, 0.5, or 5 mg/kg/day of BPA were studied. Findings showed prenatal BPA in non-monotonic manner (1) increased oxidative stress; (2) induced lipotoxicity in liver and muscle; and (3) increased aromatase and estrogen receptor expression in visceral adipose tissues. These changes are generally associated with the development of peripheral and tissue level IR and may explain the IR status and adipocyte hypertrophy observed in prenatal BPA-treated female sheep.

Effects of bisphenol A on metabolism and evidences of a mode of action mediated through endocrine disruption

Based on rodent studies after prenatal and/or perinatal or adult exposure, there is now evidence that BPA may increase metabolic disturbances eventually leading to type-2 diabetes development via an ED MoA. In particular, BPA has been shown to alter insulin synthesis and/or release by pancreatic β-cells, and insulin signaling within insulin-sensitive organs (i.e., liver, muscle, adipose tissues). This resulted in variations in the expression of specific hepatic or adipose tissue markers, which are indicative of a state of insulin resistance. These effects are considered by experts to be hallmarks of adverse hormonal effects, each leading to insulin resistance within the different insulin-sensitive tissues. Although epidemiological studies are inconclusive, these effects are considered relevant for humans, because similarities exist in homeostatic regulation of insulin production and sensitivity between rodents and humans and because evidence was also shown through in vitro experimental data using human cells or tissues.

7-Hydroxymatairesinol improves body weight, fat and sugar metabolism in C57BJ/6 mice on a high-fat diet

7-Hydroxymatairesinol (7-HMR) is a plant lignan abundant in various concentrations in plant foods. The objective of this study was to test HMRLignan™, a purified form of 7-HMR, and the correspondingPicea abiesextract (total extractP. abies; TEP) as dietary supplements on a background of a high-fat diet (HFD)-induced metabolic syndrome in mice and in the 3T3-L1 adipogenesis model. Mice, 3 weeks old, were fed a HFD for 60 d. Subgroups were treated with 3 mg/kg body weight 7-HMR (HMRLignan™) or 10 mg/kg body weight TEP by oral administration. 7-HMR and TEP limited the increase in body weight (−11 and −13 %) and fat mass (−11 and −18 %) in the HFD-fed mice. Epididymal adipocytes were 19 and −12 % smaller and the liver was less steatotic (−62 and −65 %). Serum lipids decreased in TEP-treated mice (−11 % cholesterol, −23 % LDL and −15 % TAG) and sugar metabolism was ameliorated by both lignan preparations, as shown by a more than 70 % decrease in insulin secretion and insulin resistance. The expression of several metabolic genes was modulated by the HFD with an effect that was reversed by lignan. In 3T3-L1 cells, the 7-HMR metabolites enterolactone (ENL) and enterodiol (END) showed a 40 % inhibition of cell differentiation accompanied by the inhibited expression of the adipogenic genesPPARγ,C/EBPαandaP2. Furthermore, END and ENL caused a 10 % reduction in TAG uptake in HEPA 1–6 hepatoma cells. In conclusion, 7-HMR and TEP reduce metabolic imbalances typical of the metabolic syndrome and obesity in male mice, whereas their metabolites inhibit adipogenesis and lipid uptakein vitro.

Urinary bisphenol A concentration and the risk of central obesity in Chinese adults: A prospective study

BACKGROUND

Bisphenol A (BPA) exposure has been associated with diabetes and related metabolic disorders, such as obesity, but studies of the association of urinary BPA concentrations with central obesity risk are limited. The aim of this study was to prospectively investigate the association between urinary BPA and incident central obesity in a Chinese population aged ≥40 years.

METHODS

The study followed 888 participants from Shanghai, China, who did not have central obesity at baseline (in 2009) for 4 years. Concentrations of BPA were measured in baseline morning spot urine samples. Central obesity was defined as waist circumference ≥90 cm in men and ≥80 cm in women.

RESULTS

During a mean follow-up of 4 years, 124 (14.0%) participants developed central obesity. Each 1-unit increase in log [BPA] was positively associated with a 2.30-fold risk of incident central obesity (95% confidence interval [CI] 1.39-3.78; P  < 0.001) after adjustment for confounders. Compared with the lowest tertile of urinary BPA concentration, Tertiles 2 and 3 were associated with a higher risk of incident central obesity (odds ratios 1.73 [95% CI 1.04-2.88] and 1.81 [95% CI 1.08-3.05], respectively). Stratified analysis showed significant associations of BPA with incident central obesity in women and individuals <60 years of age, with normal weight, non-smokers, non-drinkers, or non-hypertensives.

CONCLUSIONS

The results indicate that higher urinary BPA concentrations may be associated with a greater risk of incident central obesity in Chinese adults. The study emphasizes the effects of BPA exposure on metabolic risk from a public health perspective.

Plasticizers used in food-contact materials affect adipogenesis in 3T3-L1 cells

Recent studies suggest that exposure to some plasticizers, such as Bisphenol A (BPA), play a role in endocrine/metabolic dispruption and can affect lipid accumulation in adipocytes. Here, we investigated the adipogenic activity and nuclear receptor interactions of four plasticizers approved for the manufacturing of food-contact materials (FCMs) and currently considered safer alternatives. Differentiating 3T3-L1 mouse preadipocytes were exposed to scalar concentrations (0.01-25 μM) of DiNP (Di-iso-nonyl-phthalate), DiDP (Di-iso-decyl-phthalate), DEGDB (Diethylene glycol dibenzoate), or TMCP (Tri-m-cresyl phosphate). Rosiglitazone, a well-known pro-adipogenic peroxisome proliferator activated receptor gamma (PPARγ) agonist, and the plasticizer BPA were included as reference compounds. All concentrations of plasticizers were able to enhance lipid accumulation, with TMCP being the most effective one. Accordingly, when comparing in silico the ligand binding efficiencies to the nuclear receptors PPARγ and retinoid-X-receptor-alpha (RXRα), TMPC displayed the highest affinity to both receptors. Differently from BPA, the four plasticizers were most effective in enhancing lipid accumulation when added in the mid-late phase of differentiation, thus suggesting the involvement of different intracellular signalling pathways. In line with this, TMCP, DiDP, DiNP and DEGDB were able to activate PPARγ in transient transfection assays, while previous studies demonstrated that BPA acts mainly through other nuclear receptors. qRT-PCR studies showed that all plasticizers were able to increase the expression of CCAAT/enhancer binding protein β (Cebpβ) in the early steps of adipogenesis, and the adipogenesis master gene Pparγ2 in the middle phase, with very similar efficacy to that of Rosiglitazone. In addition, TMCP was able to modulate the expression of both Fatty Acid Binding Protein 4/Adipocyte Protein 2 (Fabp4/Ap2) and Lipoprotein Lipase (Lpl) transcripts in the late phase of adipogenesis. DEGDB increased the expression of Lpl only, while the phthalate DiDP did not change the expression of either late-phase marker genes Fabp4 and Lpl. Taken together, our results suggest that exposure to low, environmentally relevant doses of the plasticizers DiNP, DiDP, DEGDB and TMCP increase lipid accumulation in 3T3-L1 adipocytes, an effect likely mediated through activation of PPARγ and interference at different levels with the transcriptional cascade driving adipogenesis.

Mediating Roles of PPARs in the Effects of Environmental Chemicals on Sex Steroids

Peroxisome proliferator-activated receptors (PPARs) are ligand-activated nuclear receptors that are widely involved in various physiological functions. They are widely expressed through the reproductive system. Their roles in the metabolism and function of sex steroids and thus the etiology of reproductive disorders receive great concern. Various kinds of exogenous chemicals, especially environmental pollutants, exert their adverse impact on the reproductive system through disturbing the PPAR signaling pathway. Chemicals could bind to PPARs and modulate the transcription of downstream genes containing PPRE (peroxisome proliferator response element). This will lead to altered expression of genes related to metabolism of sex steroids and thus the abnormal physiological function of sex steroids. In this review, various kinds of environmental ligands are summarized and discussed. Their interactions with three types of PPARs are classified by various data from transcript profiles, PPRE reporter in cell line, in silico docking, and gene silencing. The review will contribute to the understanding of the roles of PPARs in the reproductive toxicology of environmental chemicals.

Firemaster® 550 and its components isopropylated triphenyl phosphate and triphenyl phosphate enhance adipogenesis and transcriptional activity of peroxisome proliferator activated receptor (Pparγ) on the adipocyte protein 2 (aP2) promoter

Firemaster^® 550 (FM550) is a chemical mixture currently used as an additive flame retardant in commercial products, and is comprised of 2-ethylhexyl-2,3,4,5-tertrabromobenzoate (TBB), bis(2-ethylhexyl) tetrabromophthalate (TBPH), triphenyl phosphate (TPP), and isopropylated triphenyl phosphate (IPTP). Animal and in vitro studies suggest that FM550, TPP and IPTP may have adipogenic effects and may exert these effects through PPARγ activation. Using murine 3T3-L1 preadipocytes, we investigated the detailed expression of transcription factors and adipogenic markers in response to FM550 and its components. Further we investigated the mechanism of action of the peroxisome proliferator-activated receptor gamma (PPARγ) on downstream targets of the receptor by focussing on the mature adipocyte marker, adipocyte protein 2 (aP2). In addition, we set to elucidate the components responsible for the adipogenic effects seen in the FM550 mixture. We show that FM550 and its components TPP, IPTP, and TBPH, but not TBB induced lipid accumulation in a dose-dependent manner. Interestingly, despite displaying enhanced lipid accumulation, TBPH did not alter the mRNA or protein expression of terminal differentiation markers. In contrast, FM550, TPP, and IPTP treatment enhanced lipid accumulation, and mRNA and protein expression of terminal differentiation markers. To further delineate the mechanisms of action of FM550 and its components we focussed on aP2 promoter activity. For this purpose we used the enhancer region of the mouse aP2 promoter using a 584-bp reporter construct containing an active PPRE located 5.4 kb away from the transcription start site of aP2. Exposure to FM550, IPTP, and TPP significantly increased PPARγ mediated aP2 enhancer activity. Furthermore, we show that TPP- and IPTP-dependent upregulation of aP2 was significantly inhibited by the selective PPARγ antagonist GW9662. In addition, chromatin immunoprecipitation experiments showed that IPTP and TPP treatment led to the recruitment of PPARγ to the regulatory region of aP2.

The Effects of Endocrine Disruptors on Adipogenesis and Osteogenesis in Mesenchymal Stem Cells: A Review

Endocrine-disrupting chemicals (EDCs) are prevalent in the environment, and epidemiologic studies have suggested that human exposure is linked to chronic diseases, such as obesity and diabetes. In vitro experiments have further demonstrated that EDCs promote changes in mesenchymal stem cells (MSCs), leading to increases in adipogenic differentiation, decreases in osteogenic differentiation, activation of pro-inflammatory cytokines, increases in oxidative stress, and epigenetic changes. Studies have also shown alteration in trophic factor production, differentiation ability, and immunomodulatory capacity of MSCs, which have significant implications to the current studies exploring MSCs for tissue engineering and regenerative medicine applications and the treatment of inflammatory conditions. Thus, the consideration of the effects of EDCs on MSCs is vital when determining potential therapeutic uses of MSCs, as increased exposure to EDCs may cause MSCs to be less effective therapeutically. This review focuses on the adipogenic and osteogenic differentiation effects of EDCs as these are most relevant to the therapeutic uses of MSCs in tissue engineering, regenerative medicine, and inflammatory conditions. This review will highlight the effects of EDCs, including organophosphates, plasticizers, industrial surfactants, coolants, and lubricants, on MSC biology.