Bisphenol A and congenital developmental defects in humans

Effects of combined exposure to two bisphenol plasticizers (BPA and BPB) on Xenopus laevis development

Due to its endocrine disruptive activity, the plastic additive Bisphenol A (BPA) is classified as substance of very high concern (EU ECHA 2017). A correlation between environmental exposure to BPA and congenital defects has been described in humans and in experimental species including the amphibian Xenopus laevis, where severe branchial defects were associated to lethality. The exposure of X. laevis embryos to the BPA analogue bisphenol B (BPB) was recently linked to similar teratogenic effects, with BPB having relative potency about 3 times higher than BPA. The combined BPA-BPB exposure is realistic as both BPA and BPB are detected in human samples and environment. Limited experimental data are available on the combined developmental toxicity of BPA and BPB. The aim of the present work is to evaluate the effects of BPA and BPB mixture in the X. laevis development model, using R-FETAX procedure. The exposure was limited to the first day of development (corresponding to the phylotypic developmental period, common to all vertebrates). Samples were monitored for lethal effects during the full six-day test period and the external morphology was evaluated at the end of the test. Mixture effects were described by modelling, using the PROAST software package. Overall data modelling showed that dose-addiction could not be rejected, suggesting a health concern for co-exposure.

Similarities in Structure and Function of UDP-Glycosyltransferase Homologs from Human and Plants

The uridine diphosphate glycosyltransferase (UGT) superfamily plays a key role in the metabolism of xenobiotics and metabolic wastes, which is essential for detoxifying those species. Over the last several decades, a huge effort has been put into studying human and mammalian UGT homologs, but family members in other organisms have been explored much less. Potentially, other UGT homologs can have desirable substrate specificity and biological activities that can be harnessed for detoxification in various medical settings. In this review article, we take a plant UGT homology, UGT71G1, and compare its structural and biochemical properties with the human homologs. These comparisons suggest that even though mammalian and plant UGTs are functional in different environments, they may support similar biochemical activities based on their protein structure and function. The known biological functions of these homologs are discussed so as to provide insights into the use of UGT homologs from other organisms for addressing human diseases related to UGTs.

Teratogenic and neuro-behavioural toxic effects of bisphenol A (BPA) and B (BPB) on Xenopus laevis development

Bisphenol A (BPA) is a plastic additive with endocrine disruptive activity, classified in 2017 by EU ECHA as substance of very high concern. A correlation between environmental exposure to BPA and congenital defects has been described in humans and in experimental species, including the amphibian Xenopus laevis. Among BPA analogues, bisphenol B (BPB) is used as alternative in different not-EU countries, including US, but seems to share with BPA its endocrine disruptor properties. Aim of the present work is the evaluation of the effects of BPB versus BPA exposure in a X. laevis developmental model. A windowed exposure (R-FETAX method) was applied covering the developmental phylotypic period (teratogenicity window), or the late tailbud stages (neuro-behavioural toxicity window, corresponding to the spontaneous swimming acquisition period). Samples were monitored for lethal effects during the full test period. External morphology evaluation and deglutition functional test were applied in any group. Abnormal tadpoles were also processed for cartilage staining. In groups exposed during neuro-behavioural toxicity window the swimming test was also applied. Lethality and malformations were obtained only in samples exposed during the teratogenicity window; these data were modelled using PROAST software and BPB relative potency resulted about 3 times higher than BPA. The day-by-day evaluation revealed that lethality was correlated to embryonic abnormal development of gills and apoptosis in gill primordia. Teratogenicity was never detected in groups exposed during the neuro-behavioural toxicity window, where some significant neuro-behavioural deficits were detected in tadpoles exposed to the highest tested concentrations of BPA and BPB.

How do mothers with young children perceive endocrine-disrupting chemicals?: an exploratory qualitative study

PURPOSE

Despite the health impacts of endocrine-disrupting chemicals (EDCs) beginning in the early stages of life, there is little research on the perception of EDCs among Korean mothers, who are primarily responsible for protecting children. This study aimed to explore how mothers with young children perceived EDCs for their concerns, the issues they faced, and the way they dealt with them.

METHODS

An exploratory qualitative design was utilized. Twelve mothers who were recruited from snowball sampling participated in voluntary interviews. Individual in-depth interviews lasting approximately 47 to 60 minutes were recorded and transcribed verbatim. The data were analyzed using qualitative content analysis as suggested by Graneheim and Lundman.

RESULTS

Four categories, 10 subcategories, and 25 condensed meaning units were identified by interpreting mothers' underlying meanings. The four categories were 'Knowledgeable yet contrasting ideas regarding EDCs,' 'Negative health impact, but more so for children,' 'Inaction or trying to minimize exposure,' and 'Need for early, reliable resources and social change.' Mothers were knowledgeable about EDCs and actively needed further education and support. While they tended to focus more on the health impact of EDCs on their children and were optimistic about their health risks, paying less attention to their preventive behaviors.

CONCLUSION

Healthcare professionals must consider mothers' perceptions of EDCs in future education and interventions regarding EDCs impact on women's life stages such as puberty, pregnancy, and childrearing. Also preventive strategies that can be applied to their daily lives are needed.

Associations among bisphenol A, its analogs, and chlorinated derivatives in placenta and risk for neural tube defects: A case-control study

Bisphenol A (BPA) and its analogs such as bisphenol Z (BPZ) are widely used in the production of consumer products, but few studies have investigated the associations among BPA, its analogs, and chlorinated derivatives (collectively, BPs) and risk for NTDs. This study investigated the associations between concentrations of BPs in the placenta and risk for NTDs. This was a case-control study including 122 NTDs and 164 controls. BPs in the placenta were determined using liquid chromatography-tandem mass spectrometry. The associations between BPs and NTD risk were evaluated using conventional logistic regression and weighted quantile sum regression (WQS) models. In the logistic regression, exposure to higher levels of BPA and BPZ was associated with increased NTD risk (odds ratio [OR] = 3.17, 95 % confidence interval [CI], 1.22-8.22; OR = 3.11, 95 % CI, 1.20-8.09, respectively). Meanwhile, a significant dose-response relationship was found between BPA and BPZ concentrations and NTD risk. In the WQS model, a quartile increase in WQS index resulted in 4.34 (95 % CI: 1.69, 11.20) higher odds for NTDs, and BPA and BPZ accounted for most of the weight index in the joint effects of BPs. In conclusion, high levels of BPs in the placenta are associated with increased risk for NTDs, of which BPA and BPZ are important risk factors.

An Overview of the Health Effects of Bisphenol A from a One Health Perspective

Bisphenol A (BPA) is a chemical compound, considered as an "emerging pollutant", that appears ubiquitously, contaminating the environment and food. It is an endocrine disruptor, found in a multitude of consumer products, as it is a constituent of polycarbonate used in the manufacture of plastics and epoxy resins. Many studies have evaluated the effects of BPA, using a wide range of doses and animal models. In this work, we carried out a review of relevant research related to the effects of BPA on health, through studies performed at different doses, in different animal models, and in human monitoring studies. Numerous effects of BPA on health have been described; in different animal species, it has been reported that it interferes with fertility in both females and males and causes alterations in their offspring, as well as being associated with an increase in hormone-dependent pathologies. Similarly, exposure to BPA has been related to other diseases of great relevance in public health such as obesity, hypertension, diabetes, or neurodevelopmental disorders. Its ubiquity and nonmonotonic behavior, triggering effects at exposure levels considered "safe", make it especially relevant when both animal and human populations are constantly and inadvertently exposed to this compound. Its effects at low exposure levels make it essential to establish safe exposure levels, and research into the effects of BPA must continue and be focused from a "One Health" perspective to take into account all the factors that could intervene in the development of a disease in any exposed organism.

Exploring the potential of ToxCast™ data for mechanism-based prioritization of chemicals in regulatory context: Case study with priority existing chemicals (PECs) under K-REACH

Recent studies have highlighted the potential of ToxCast™ database to mechanism-based prioritization of chemicals. To explore the applicability of ToxCast data in the context of regulatory inventory chemicals, we screened 510 priority existing chemicals (PECs) regulated under the Act on the Registration and Evaluation of Chemical Substances (K-REACH) using ToxCast bioassays. In our analysis, a hit-call data matrix containing 298984 chemical-gene interactions was computed for 949 bioassays with the intended target genes, which enabled the identification of the putative toxicity mechanisms. Based on the reactivity to the chemicals, we analyzed 412 bioassays whose intended target gene families were cytochrome P450, oxidoreductase, transporter, nuclear receptor, steroid hormone, and DNA-binding. We also identified 141 chemicals based on their reactivity in the bioassays. These chemicals are mainly in consumer products including colorants, preservatives, air fresheners, and detergents. Our analysis revealed that in vitro bioactivities were involved in the relevant mechanisms inducing in vivo toxicity; however, this was not sufficient to predict more hazardous chemicals. Overall, the current results point to a potential and limitation in using ToxCast data for chemical prioritization in regulatory context in the absence of suitable in vivo data.

A screening test proposal for congenital defects based on maternal serum metabolomics profile

BACKGROUND

Historically, noninvasive techniques are only able to identify chromosomal anomalies that accounted for <50% of all congenital defects; the other congenital defects are diagnosed via ultrasound evaluations in the later stages of pregnancy. Metabolomic analysis may provide an important improvement, potentially addressing the need for novel noninvasive and multicomprehensive early prenatal screening tools. A growing body of evidence outlines notable metabolic alterations in different biofluids derived from pregnant women carrying fetuses with malformations, suggesting that such an approach may allow the discovery of biomarkers common to most fetal malformations. In addition, metabolomic investigations are inexpensive, fast, and risk-free and often generate high performance screening tests that may allow early detection of a given pathology.

OBJECTIVE

This study aimed to evaluate the diagnostic accuracy of an ensemble machine learning model based on maternal serum metabolomic signatures for detecting fetal malformations, including both chromosomal anomalies and structural defects.

STUDY DESIGN

This was a multicenter observational retrospective study that included 2 different arms. In the first arm, a total of 654 Italian pregnant women (334 cases with fetuses with malformations and 320 controls with normal developing fetuses) were enrolled and used to train an ensemble machine learning classification model based on serum metabolomics profiles. In the second arm, serum samples obtained from 1935 participants of the New Zealand Screening for Pregnancy Endpoints study were blindly analyzed and used as a validation cohort. Untargeted metabolomics analysis was performed via gas chromatography-mass spectrometry. Of note, 9 individual machine learning classification models were built and optimized via cross-validation (partial least squares-discriminant analysis, linear discriminant analysis, naïve Bayes, decision tree, random forest, k-nearest neighbor, artificial neural network, support vector machine, and logistic regression). An ensemble of the models was developed according to a voting scheme statistically weighted by the cross-validation accuracy and classification confidence of the individual models. This ensemble machine learning system was used to screen the validation cohort.

RESULTS

Significant metabolic differences were detected in women carrying fetuses with malformations, who exhibited lower amounts of palmitic, myristic, and stearic acids; N-α-acetyllysine; glucose; L-acetylcarnitine; fructose; para-cresol; and xylose and higher levels of serine, alanine, urea, progesterone, and valine (P<.05), compared with controls. When applied to the validation cohort, the screening test showed a 99.4%±0.6% accuracy (specificity of 99.9%±0.1% [1892 of 1894 controls correctly identified] with a sensitivity of 78%±6% [32 of 41 fetal malformations correctly identified]).

CONCLUSION

This study provided clinical validation of a metabolomics-based prenatal screening test to detect the presence of congenital defects. Further investigations are needed to enable the identification of the type of malformation and to confirm these findings on even larger study populations.

Plant species compositions alleviate toxicological effects of bisphenol A by enhancing growth, antioxidant defense system, and detoxification

Bisphenol A (BPA), a broadly disseminated endocrine disturbing chemicals in environment, is harmful to creatures and plants. Plants can uptake and metabolize BPA, but a single plant species ability is limited. Undeniably, plant species compositions have a more vital ability to remove pollutants than a single plant species. However, the mechanisms of plant species compositions alleviating toxicological effects of bisphenol A are poorly understood. Here, we administered plant species compositions, which based on a full-factorial design of Phragmites australis (A), Typha latifolia (B), and Arundo donax (C), to unveil their role in BPA exposure. The results illustrated that the root activity, biomass, and photosynthetic pigment contents of the mixed hydroponic group (e.g., sp(ABC)) were significantly increased under concentration of BPA(1.5, 5, and 10 mg L^-1), which showed that the root activity, fresh weight, dry weight, chlorophyll a, and total chlorophyll contents of shoots were increased. While mixed-hydroponic culture groups (e.g., sp(AB), sp(ABC)) significantly increased antioxidant enzyme activity and antioxidant substances under concentration of BPA(5 and 10 mg L^-1), it astoundingly diminished responsive oxygen species (ROS) and malondialdehyde (MDA) substance, proposing that mixed-hydroponic culture groups calmed oxidative stress. Further analysis revealed that mixed-hydroponic culture groups (e.g., sp(AB), sp(AC), sp(ABC)) of 1.5, 5, and 10 mg L^-1 BPA exposure significantly increased detoxification enzyme activity of NADPH-cytochrome P450 reductase (CPR), glutathione S-transferase (GST), and glycosyltransferase (GT). Moreover, mixed-hydroponic culture groups (e.g., sp(AB), sp(AC), sp(ABC)) decreased the BPA substance in leaves, proposing that mixed-hydroponic culture groups advanced BPA metabolism by improving CPR, GST, and GT enzyme activities. These results demonstrated that a mixed-hydroponic culture strategy can alleviate BPA phytotoxicity and possibly offer natural and potential phytoremediation methods for BPA.

Cardiac toxicity from bisphenol A exposure in human-induced pluripotent stem cell-derived cardiomyocytes

Bisphenol A (BPA) is a well-known endocrine-disrupting chemical that is widely used in a variety of products, including plastics, medical equipment and receipts. Hence, most people are exposed to BPA through the skin, via inhalation and via the digestive system, and such exposure has been linked to cardiovascular diseases including coronary artery disease, hypertension, atherosclerosis, and myocardial infarction. However, the underlying mechanisms of cardiac dysfunction caused by BPA remain poorly understood. In this study, we found that BPA exposure altered cardiac function in human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs). Acute BPA exposure in hiPSC-CMs resulted in reduced field potential, as measured by multielectrode array (MEA). Furthermore, we observed that BPA dose-dependently inhibited I_Ca, I_Na or I_Kr channels. In addition, BPA exposure dose-dependently inhibited calcium transients and contraction in hiPSC-CMs. Our findings suggest that BPA exposure leads to cardiac dysfunction and cardiac risk factors such as arrhythmia.

Multi-Systemic Alterations by Chronic Exposure to a Low Dose of Bisphenol A in Drinking Water: Effects on Inflammation and NAD+-Dependent Deacetylase Sirtuin1 in Lactating and Weaned Rats

Bisphenol A (BPA) is largely used as a monomer in some types of plastics. It accumulates in tissues and fluids and is able to bypass the placental barrier, affecting various organs and systems. Due to huge developmental processes, children, foetuses, and neonates could be more sensitive to BPA-induced toxicity. To investigate the multi-systemic effects of chronic exposure to a low BPA dose (100 μg/L), pregnant Wistar rats were exposed to BPA in drinking water during gestation and lactation. At weaning, newborn rats received the same treatments as dams until sex maturation. Free and conjugated BPA levels were measured in plasma and adipose tissue; the size of cerebral ventricles was analysed in the brain; morpho-functional and molecular analyses were carried out in the liver with a focus on the expression of inflammatory cytokines and Sirtuin 1 (Sirt1). Higher BPA levels were found in plasma and adipose tissue from BPA treated pups (17 PND) but not in weaned animals. Lateral cerebral ventricles were significantly enlarged in lactating and weaned BPA-exposed animals. In addition, apart from microvesicular steatosis, liver morphology did not exhibit any statistically significant difference for morphological signs of inflammation, hypertrophy, or macrovesicular steatosis, but the expression of inflammatory cytokines, Sirt1, its natural antisense long non-coding RNA (Sirt1-AS LncRNA) and histone deacetylase 1 (Hdac1) were affected in exposed animals. In conclusion, chronic exposure to a low BPA dose could increase the risk for disease in adult life as a consequence of higher BPA circulating levels and accumulation in adipose tissue during the neonatal period.

Prenatal Bisphenol a Exposure, DNA Methylation, and Low Birth Weight: A Pilot Study in Taiwan

Prenatal exposure to bisphenol A (BPA) may increase the risk of abnormal birth outcomes, and DNA methylation might mediate these adverse effects. This study aimed to investigate the effects of maternal BPA exposure on maternal and fetal DNA methylation levels and explore whether epigenetic changes are related to the associations between BPA and low birth weight. We collected urine and blood samples originating from 162 mother-infant pairs in a Taiwanese cohort study. We measured DNA methylation using the Illumina Infinium HumanMethylation 450 BeadChip in 34 maternal blood samples with high and low BPA levels based on the 75th percentile level (9.5 μg/g creatinine). Eighty-seven CpGs with the most differentially methylated probes possibly interacting with BPA exposure or birth weight were selected using two multiple regression models. Ingenuity pathway analysis (IPA) was utilized to narrow down 18 candidate CpGs related to disease categories, including developmental disorders, skeletal and muscular disorders, skeletal and muscular system development, metabolic diseases, and lipid metabolism. We then validated these genes by pyrosequencing, and 8 CpGs met the primer design score requirements in 82 cord blood samples. The associations among low birth weight, BPA exposure, and DNA methylation were analyzed. Exposure to BPA was associated with low birth weight. Analysis of the epigenome-wide findings did not show significant associations between BPA and DNA methylation in cord blood of the 8 CpGs. However, the adjusted odds ratio for the dehydrogenase/reductase member 9 (DHRS9) gene, at the 2nd CG site, in the hypermethylated group was significantly associated with low birth weight. These results support a role of BPA, and possibly DHRS9 methylation, in fetal growth. However, additional studies with larger sample sizes are warranted.

Human biomonitoring of bisphenol A along pregnancy: An exposure reconstruction of the EXHES-Spain cohort

This study was aimed at reconstructing the exposure to bisphenol (BPA) of 60 pregnant women from the EXHES-Spain cohort. A biomonitoring study was conducted by determining BPA levels in urine samples over the three trimesters of pregnancy. Moreover, the correlations between BPA levels and the role of different potential exposure sources, with special emphasis on the dietary intake, were also studied. Urine samples were subjected to dispersive liquid-liquid microextraction and the subsequent analysis via gas chromatography-mass spectrometry. BPA was detected in 76% of the urine samples. A significant decrease of urinary BPA levels was observed along pregnancy, as mean concentrations of creatinine-adjusted BPA were 4.64, 4.84 and 2.51 μg/g in the first, second and third trimester, respectively. This decrease was essentially associated with changes in the dietary habits of the pregnant women, including a lower intake of canned food and drinks. However, the potential role of other pregnancy-related biochemical or physiological factors should not be disregarded. Very interestingly, significant differences in urine BPA levels were found according to the fruit consumption pattern, as women who ate more citrus fruits showed lower BPA concentrations in urine. The reconstructed exposure to BPA was estimated in 0.072, 0.069 and 0.038 μg BPA/kg of body weight/day in the first, second and third trimesters, respectively. These values are far below the temporary tolerable daily intake (t-TDI) established by the EFSA.

Congenital heart diseases and parental occupational exposure in a Hungarian case-control study in 1997 to 2002

The etiology of congenital heart diseases is not fully understood yet, however, endocrine disrupting chemicals may have a causative role in their development. The purpose of our study was to examine the association between congenital heart diseases and periconceptional parental occupational exposure to endocrine disrupting chemicals. In our Hungarian population-based case-control study, we examined 2263 live born cases with any congenital heart disease and 6789 matched controls selected between years 1997 to 2002. Occupational exposure was assessed with a job-exposure matrix developed for endocrine disrupting chemicals. Conditional multiple logistic regression analyses were performed to test associations between parental occupational exposure to endocrine disrupting chemicals and congenital heart diseases of the offspring as a whole and by congenital heart disease subtypes. The prevalence of exposure to endocrine disrupting chemicals was 4.5% for both case and control mothers and 19.1% and 19.4% for case and control fathers, respectively. We found a positive association between paternal pesticide (adjusted odds ratio = 1.66, 95% confidence interval: 1.03-2.69) and alkylphenolic compound exposure (adjusted odds ratio = 1.95, 95% confidence interval: 1.30-2.93) and the development of patent ductus arteriosus in the offspring. Alkylphenolic compound exposure occurred among painters, famers, and those working in the food service industry, while pesticide exposure occurred predominantly among farm workers. We identified that certain occupations may increase the occurrence of certain congenital heart disease phenotypes in the offspring. By paying closer attention to those working in these areas, antenatal detection rates of congenital heart diseases may be improved.

Road impact in a protected area with rich biodiversity: the case of the Sebitoli road in Kibale National Park, Uganda

While road network expansion is crucial for economic development, it can cause a notable disturbance of fauna, especially in protected area in terms of habitat fragmentation, risk of collision, and also indirect threat such as pollution. In this study, we monitored the 4.6-km long tarmac road crossing the Kibale National Park in Uganda, home to a rich variety of wild species including the endangered chimpanzees. We evaluated the effects of collisions and pollution, as well as the impact of the renovation process in terms of disturbance and the mitigation measures deployed. This survey reports the death of 24 wild animals killed by cars, including two chimpanzees. The atmospheric concentrations of O₃, NO₂, SO₂, and BTEX did not exceed recommended limits. More than 5000 plastic bottles were collected along the road within 4 months, and for the first time, the presence of BPA and BPS was detected in the hairs of wild chimpanzees. The road bisecting the Kibale National Park poses a high danger in terms of traffic and an underestimated risk related to plastic pollution. Measures (signpost, speed bumps) should be urgently deployed to decrease the risk posed by the renovated road for emblematic species such as chimpanzees, which are crucial for tourism and economy in Uganda.

Histopathologic, apoptotic and autophagic, effects of prenatal bisphenol A and/or di(2-ethylhexyl) phthalate exposure on prepubertal rat testis

Bisphenol A (BPA) and di(2-ethylhexyl) phthalate (DEHP) are endocrine-disrupting chemicals (EDCs) used in a wide variety of industrial products as plasticizers. Exposure to EDCs, particularly in mixtures, in prenatal and early postnatal periods may lead to unwanted effects and can cause both developmental and reproductive problems. In this study, we aimed to determine the individual and combined effects of prenatal and lactational exposure to BPA and/or DEHP on testicular histology, apoptosis, and autophagic proteins. Pregnant Sprague-Dawley rats (n = 3) were divided into four groups (control, BPA (50 mg/kg/day), DEHP (30 mg/kg/day), and BPA (50 mg/kg/day) + DEHP (30 mg/kg/day)) and dosed by oral gavage during pregnancy and lactation. The male offspring (n = 6) from each group were chosen randomly, and their testicular examinations were performed on the twelfth week. The results showed that fetal and neonatal exposure to BPA and DEHP could lead to significant testicular histopathological alterations and cause increases in apoptosis markers (as evidenced by increases in caspase 3 and caspase 8 levels; increased TUNEL-positive spermatogonia and TUNEL-positive testicular apoptotic cells) and autophagic proteins (as evidenced by increased LC3 and Beclin levels and decreased p62 levels) in testicular tissue. We can suggest that EDCs cause more dramatic changes in both testicular structure and cell death when there is combined exposure.

Oxidative Stress and BPA Toxicity: An Antioxidant Approach for Male and Female Reproductive Dysfunction

Bisphenol A (BPA) is a non-persistent anthropic and environmentally ubiquitous compound widely employed and detected in many consumer products and food items; thus, human exposure is prolonged. Over the last ten years, many studies have examined the underlying molecular mechanisms of BPA toxicity and revealed links among BPA-induced oxidative stress, male and female reproductive defects, and human disease. Because of its hormone-like feature, BPA shows tissue effects on specific hormone receptors in target cells, triggering noxious cellular responses associated with oxidative stress and inflammation. As a metabolic and endocrine disruptor, BPA impairs redox homeostasis via the increase of oxidative mediators and the reduction of antioxidant enzymes, causing mitochondrial dysfunction, alteration in cell signaling pathways, and induction of apoptosis. This review aims to examine the scenery of the current BPA literature on understanding how the induction of oxidative stress can be considered the "fil rouge" of BPA's toxic mechanisms of action with pleiotropic outcomes on reproduction. Here, we focus on the protective effects of five classes of antioxidants-vitamins and co-factors, natural products (herbals and phytochemicals), melatonin, selenium, and methyl donors (used alone or in combination)-that have been found useful to counteract BPA toxicity in male and female reproductive functions.

The Redox Theory of Development

Significance: The geological record shows that as atmospheric O2 levels increased, it concomitantly coincided with the evolution of metazoans. More complex, higher organisms contain a more cysteine-rich proteome, potentially as a means to regulate homeostatic responses in a more O2-rich environment. Regulation of redox-sensitive processes to control development is likely to be evolutionarily conserved. Recent Advances: During early embryonic development, the conceptus is exposed to varying levels of O2. Oxygen and redox-sensitive elements can be regulated to promote normal development, defined as changes to cellular mass, morphology, biochemistry, and function, suggesting that O2 is a developmental morphogen. During periods of O2 fluctuation, embryos are "reprogrammed," on the genomic and metabolic levels. Reprogramming imparts changes to particular redox couples (nodes) that would support specific post-translational modifications (PTMs), targeting the cysteine proteome to regulate protein function and development. Critical Issues: Major developmental events such as stem cell expansion, proliferation, differentiation, migration, and cell fate decisions are controlled through oxidative PTMs of cysteine-based redox nodes. As such, timely coordinated redox regulation of these events yields normal developmental outcomes and viable species reproduction. Disruption of normal redox signaling can produce adverse developmental outcomes. Future Directions: Furthering our understanding of the redox-sensitive processes/pathways, the nature of the regulatory PTMs involved in development and periods of activation/sensitivity to specific developmental pathways would greatly support the theory of redox regulation of development, and would also provide rationale and direction to more fully comprehend poor developmental outcomes, such as dysmorphogenesis, functional deficits, and preterm embryonic death.

Neuro-toxic and Reproductive Effects of BPA

Background:

Bisphenol A (BPA) is one of the highest volume chemicals produced worldwide. It has recognized activity as an endocrine-disrupting chemical and has suspected roles as a neurological and reproductive toxicant. It interferes in steroid signaling, induces oxidative stress, and affects gene expression epigenetically. Gestational, perinatal and neonatal exposures to BPA affect developmental processes, including brain development and gametogenesis, with consequences on brain functions, behavior, and fertility.

Methods:

This review critically analyzes recent findings on the neuro-toxic and reproductive effects of BPA (and its ana-logues), with focus on neuronal differentiation, synaptic plasticity, glia and microglia activity, cognitive functions, and the central and local control of reproduction.

Results:

BPA has potential human health hazard associated with gestational, peri- and neonatal exposure. Beginning with BPA’s disposition, this review summarizes recent findings on the neurotoxicity of BPA and its analogues, on neuronal dif-ferentiation, synaptic plasticity, neuro-inflammation, neuro-degeneration, and impairment of cognitive abilities. Furthermore, it reports the recent findings on the activity of BPA along the HPG axis, effects on the hypothalamic Gonadotropin Releas-ing Hormone (GnRH), and the associated effects on reproduction in both sexes and successful pregnancy.

Conclusion:

BPA and its analogues impair neuronal activity, HPG axis function, reproduction, and fertility. Contrasting re-sults have emerged in animal models and human. Thus, further studies are needed to better define their safety levels. This re-view offers new insights on these issues with the aim to find the “fil rouge”, if any, that characterize BPA’s mechanism of action with outcomes on neuronal function and reproduction.

Involvement of the Endocrine-Disrupting Chemical Bisphenol A (BPA) in Human Placentation

Background: Endocrine-disrupting chemicals (EDCs) are environmental chemicals/toxicants that humans are exposed to, interfering with the action of multiple hormones. Bisphenol A (BPA) is classified as an EDC with xenoestrogenic activity with potentially adverse effects in reproduction. Currently, a significant knowledge gap remains regarding the complete spectrum of BPA-induced effects on the human placenta. As such, the present study examined the effects of physiologically relevant doses of BPA in vitro. Methods: qRT-PCR, Western blotting, immunofluorescence, ELISA, microarray analyses, and bioinformatics have been employed to study the effects of BPA using nonsyncytialised (non-ST) and syncytialised (ST) BeWo cells. Results: Treatment with 3 nM BPA led to an increase in cell number and altered the phosphorylation status of p38, an effect mediated primarily via the membrane-bound estrogen receptor (GPR30). Nonbiased microarray analysis identified 1195 and 477 genes that were differentially regulated in non-ST BeWo cells, whereas in ST BeWo cells, 309 and 158 genes had altered expression when treated with 3 and 10 nM, respectively. Enriched pathway analyses in non-ST BeWo identified a leptin and insulin overlap (3 nM), methylation pathways (10 nM), and differentiation of white and brown adipocytes (common). In the ST model, most significantly enriched were the nuclear factor erythroid 2-related factor 2 (NRF2) pathway (3 nM) and mir-124 predicted interactions with cell cycle and differentiation (10 nM). Conclusion: Collectively, our data offer a new insight regarding BPA effects at the placental level, and provide a potential link with metabolic changes that can have an impact on the developing fetus.

In utero Bisphenol A Exposure Is Linked with Sex Specific Changes in the Transcriptome and Methylome of Human Amniocytes

CONTEXT

Prenatal exposure to bisphenol A (BPA) is linked to obesity and diabetes but the molecular mechanisms driving these phenomena are not known. Alterations in deoxyribonucleic acid (DNA) methylation in amniocytes exposed to BPA in utero represent a potential mechanism leading to metabolic dysfunction later in life.

OBJECTIVE

To profile changes in genome-wide DNA methylation and expression in second trimester human amniocytes exposed to BPA in utero.

DESIGN

A nested case-control study was performed in amniocytes matched for offspring sex, maternal race/ethnicity, maternal age, gestational age at amniocentesis, and gestational age at birth. Cases had amniotic fluid BPA measuring 0.251 to 23.74 ng/mL. Sex-specific genome-wide DNA methylation analysis and RNA-sequencing (RNA-seq) were performed to determine differentially methylated regions (DMRs) and gene expression changes associated with BPA exposure. Ingenuity pathway analysis was performed to identify biologically relevant pathways enriched after BPA exposure. In silico Hi-C analysis identified potential chromatin interactions with DMRs.

RESULTS

There were 101 genes with altered expression in male amniocytes exposed to BPA (q < 0.05) in utero, with enrichment of pathways critical to hepatic dysfunction, collagen signaling and adipogenesis. Thirty-six DMRs were identified in male BPA-exposed amniocytes and 14 in female amniocyte analysis (q < 0.05). Hi-C analysis identified interactions between DMRs and 24 genes with expression changes in male amniocytes and 12 in female amniocytes (P < 0.05).

CONCLUSION

In a unique repository of human amniocytes exposed to BPA in utero, sex-specific analyses identified gene expression changes in pathways associated with metabolic disease and novel DMRs with potential distal regulatory functions.

An ultrasensitive fluorescent aptasensor based on truncated aptamer and AGET ATRP for the detection of bisphenol A

Given the gigantic harmfulness of bisphenol A (BPA), a novel and ultrasensitive aptasensor, which employs the truncated BPA aptamer, click chemistry, and activators generated by electron transfer for atom transfer radical polymerization (AGET ATRP), was developed herein for the quantitative determination of BPA. Firstly, hairpin DNAs (hairpins) with a thiol at the 5' end and an azide group at the 3' end were conjugated with aminated magnetic beads (MBs) through heterobifunctional cross-linkers. BPA truncated aptamer (ssDNA-A) hybridizes with its complementary single-stranded DNA (ssDNA-B) to form double-stranded DNA. In the presence of BPA, ssDNA-A specifically captures BPA, and then ssDNA-B is released. Subsequently, the ssDNA-B hybridizes with hairpins to expose the azide group near the surface of the MBs. Then, propargyl-2-bromoisobutyrate (PBIB), the initiator of AGET ATRP containing alkynyl group, was conjugated with azide group of hairpins via the Cu(I)-catalyzed azide-alkyne cycloaddition (CuAAC). Consequently, a large number of fluorescein-o-acrylate (FA) were introduced to the MBs through AGET ATRP, resulting in that the fluorescence intensity was increased dramatically. Obviously, the fluorescence intensity was especially sensitive to the change of BPA concentration, and this method can be used in quantitative determination of BPA. Under optimal conditions, a broad liner range from 100 fM to 100 nM and a low limit of detection (LOD) of 6.6 fM were obtained. Moreover, the method exhibits not only excellent specificity for BPA detection over BPA analogues but high anti-interference ability in real water sample detection, indicating that it has huge application prospect in food safety and environment monitoring.

Hypospadias risk is increased with maternal residential exposure to hormonally active hazardous air pollutants

BACKGROUND

With the increasing birth prevalence of hypospadias, there is growing concern for pollutant exposure interfering with normal penile development. We assess the association between hypospadias and hormonally active hazardous air pollutants (HAHAPs) through a nationwide database of hazardous air pollutants and the Texas Birth Defects Registry (TBDR).

METHODS

Using the TBDR, we identified 8,981 nonsyndromic isolated hypospadias cases from 1999 to 2008. Birth certificate controls were matched for birth year at a 10:1 ratio to cases. Estimated HAHAP concentrations from the 2005 U.S. EPA National-Scale Air Toxics Assessment were used to assign exposure based on maternal residence at birth. Exposure levels were categorized as quintiles based on the distribution in controls. Logistic regression was used to calculate the odds ratio (OR) and 95% confidence interval (CI) for each increasing exposure category of selected HAHAPs.

RESULTS

Of the 10 HAHAPs studied, seven were significantly associated with hypospadias risk. The HAHAP that was most strongly associated with hypospadias was phenol, which was associated with risk in all groups except the high exposure group. Cumulative HAHAP exposure demonstrated a modest increase in hypospadias risk (OR 1.15, 95% CI: 1.07-1.24, p < 0.001) in the medium and medium-high quintiles.

CONCLUSIONS

While maternal exposure to some HAHAPs was significantly associated with the risk of hypospadias in male offspring, the effects were modest, and no dose-response effects were observed. Future work should employ biomarkers of exposure to better delineate the relationship.

Bisphenol A and adverse pregnancy outcomes: a systematic review of the literature

PURPOSE

Bisphenol A is a chemical compound related to adverse maternal and neonatal outcomes. The purpose of the present systematic review is to summarize the current knowledge in the field.

MATERIALS AND METHODS

We systematically searched the Medline (1966-2017), Scopus (2004-2017), Clinicaltrials.gov (2008-2017), Cochrane Central Register of Controlled Trials CENTRAL (1999-2017) databases.

RESULTS

Thirty-five studies were included in the present systematic review. According to our findings, BPA has a direct negative impact on maternal, fetal, and neonatal outcomes, including birthweight, rates of preterm birth, developmental defects, and recurrent miscarriage. Data in the field of preeclampsia and gestational diabetes mellitus remain inconclusive because current research is very limited.

CONCLUSIONS

BPA exposure during pregnancy can result in significant antenatal pathology; hence, occupational exposure should be at least discouraged during this period. However, cross-sectional studies in the field that would assess the levels of exposure at timely intervals are still lacking, therefore, the actual impact of BPA remains unclear.

Determinants of Risk Perception Related to Exposure to Endocrine Disruptors during Pregnancy: A Qualitative and Quantitative Study on French Women

Endocrine disruptors (EDCs) are known as environmental exposure factors. However, they are rarely reported by health professionals in clinical practice, particularly during pregnancy, even though they are associated with many deleterious consequences. The objectives of this study were to estimate the risk perception of pregnant women related to EDC exposure and to evaluate its determinants. A qualitative study based on the Health Belief Model was carried out through interviews of pregnant women and focus group with perinatal, environmental health and prevention professionals in 2015 in the city of Poitiers, France. Then, determinants of risk perception were included in a questionnaire administered to 300 women in the perinatal period through a quantitative study. Scores were subsequently calculated. Perception of EDC risk was defined as perceived severity for different stages of the infant’s development and perceived susceptibility to EDC exposure. The determinants reported in the qualitative study were: age, strong maternal figure, socio-professional category, level of knowledge, and involuntariness of exposure. Age and level of knowledge were confirmed in our statistical model as determinants. Mean score of EDC risk perception was 55.0 ± 18.3 on 100 points. Our study should guide healthcare providers when advising pregnant women about EDC and environmental exposure. Our score for perceived EDC risk and assessment of its known determinants may help to assess the impact and the relevance of prevention programs dedicated to reducing exposure to EDC during pregnancy.

The Influence of Bisphenol A (BPA) on Neuregulin 1-Like Immunoreactive Nerve Fibers in the Wall of Porcine Uterus

Bisphenol A (BPA), a substance commonly used in the manufacture of plastics, shows multidirectional negative effects on humans and animals. Due to similarities to estrogens, BPA initially leads to disorders in the reproductive system. On the other hand, it is known that neuregulin 1 (NRG-1) is an active substance which enhances the survivability of cells, inhibits apoptosis, and protects tissues against damaging factors. Because the influence of BPA on the nervous system has also been described, the aim of the present study was to investigate for the first time the influence of various doses of BPA on neuregulin 1-like immunoreactive (NRG-1-LI) nerves located in the porcine uterus using the routine single- and double-immunofluorescence technique. The obtained results have shown that BPA increases the number and affects the neurochemical characterization of NRG-1-LI in the uterus, and changes are visible even under the impact of small doses of this toxin. The character of observed changes depended on the dose of BPA and the part of the uterus studied. These observations suggest that NRG-1 in nerves supplying the uterus may play roles in adaptive and protective mechanisms under the impact of BPA.

Advances in sensing and biosensing of bisphenols: A review

Bisphenols (BPs) are well known endocrine disrupting chemicals (EDCs) that cause adverse effects on the environment, biotic life and human health. BPs have been studied extensively because of an increasing concern for the safety of the environment and for human health. They are major raw materials for manufacturing polycarbonates, thermal papers and epoxy resins and are considered hazardous environmental contaminants. A vast array of sensors and biosensors have been developed for the sensitive screening of BPs based on carbon nanomaterials (carbon nanotubes, fullerenes, graphene and graphene oxide), quantum dots, metal and metal oxide nanocomposites, polymer nanocomposites, metal organic frameworks, ionic liquids and molecularly imprinted polymers. This review is devoted mainly to a variety of sensitive, selective and reliable sensing and biosensing methods for the detection of BPs using electrochemistry, fluorescence, colorimetry, surface plasmon resonance, luminescence, ELISAs, circular dichroism, resonance Rayleigh scattering and adsorption techniques in plastic products, food samples, food packaging, industrial wastes, pharmaceutical products, human body fluids and many other matrices. It summarizes the advances in sensing and biosensing methods for the detection of BPs since 2010. Furthermore, the article discusses challenges and future perspectives in the development of novel sensing methods for the detection of BP analogs.

Effect of bisphenol A on reproductive processes: A review of in vitro, in vivo and epidemiological studies

As bisphenol A (BPA) is characterized by a pronounced influence on human hormonal regulation, particular attention has been aimed at understanding its role in reproductive processes in males and females, as well as on fetal development. Owing to the increasing number of alarming reports on the negative consequences of the presence of BPA in human surroundings, more and more studies are being undertaken to clarify the negative effects of BPA on human reproductive processes. The aim of this work was to collect and summarize data on the influence of BPA exposure on reproductive health. Based on an analysis of selected publications it was stated that there is strong proof confirming that BPA is an ovarian, uterine and prostate toxicant at a level below the lowest observed adverse effect level (50 mg kg^-1 bodyweight) as well as a level below the proposed safe level (4 μg kg^-1 bodyweight). It seems there is also reliable evidence in relation to the negative effect of BPA on sperm quality and motility. Limited evidence also pertains to the case of the potential of BPA to affect polycystic ovary syndrome occurrence. Although in epidemiological studies this disease was common, in studies on animal models such results were still not confirmed. No unambiguous results of epidemiological studies and with animal models were obtained in relation to the evaluation of associations between BPA and implantation failure in women, evaluation of associations between BPA and sexual dysfunction in men, and impact of BPA on birth rate, birth weight and length of gestation. Copyright © 2017 John Wiley & Sons, Ltd.

From BPA to its analogues: Is it a safe journey?

Bisphenol-A (BPA) is one of the most abundant synthetic chemicals in the world due to its uses in plastics. Its widespread exposure vis-a-vis low dose effects led to a reduction in its safety dose and imposition of ban on its use in infant feeding bottles. This restriction paved the way for the gradual market entry of its analogues. However, their structural similarity to BPA has put them under surveillance for endocrine disrupting potential. The application of these analogues is increasing and so are the studies reporting their toxicity. This review highlights the reasons which led to the ban of BPA and also reports the exposure and toxicological data available on its analogues. Hence, this compilation is expected to answer in a better way whether the replacement of BPA by these analogues is safer or more harmful?

Maternal urinary bisphenol A levels and infant low birth weight: A nested case-control study of the Health Baby Cohort in China

BACKGROUND

Exposure to bisphenol A (BPA), a known endocrine disruptor, has been demonstrated to affect fetal development in animal studies, but findings in human studies have been inconsistent.

OBJECTIVES

We investigated whether maternal exposure to BPA during pregnancy is associated with an increased risk of infant low birth weight (LBW).

METHODS

A total 452 mother-infant pairs (113 LBW cases and 339 matched controls) were selected from the participants enrolled in the prospective Health Baby Cohort (HBC) in Wuhan city, China, during 2012-2014. BPA concentrations were measured in maternal urine samples collected at delivery, and the information of birth outcomes was retrieved from the medical records. A conditional logistic regression was used to evaluate the relationship between urinary BPA levels and LBW.

RESULTS

Mothers with LBW infants had significantly higher urinary BPA levels (median: 4.70μg/L) than the control mothers (median: 2.25μg/L) (p<0.05). Increased risk of LBW was associated with higher maternal urinary levels of BPA [adjusted odds ratio (OR)=3.13 for the medium tertile, 95% confidence interval (CI): 1.21, 8.08; adjusted OR=2.49 for the highest tertile, 95% CI: 0.98, 6.36]. The association was more pronounced among female infants than among male infants, with a statistical evidence of heterogeneity in risk (p=0.03).

CONCLUSIONS

Prenatal exposure to higher levels of BPA may potentially increase the risk of delivering LBW infants, especially for female infants. This is the first case-control study to examine the association in China.