Actions of Bisphenol A and Bisphenol S on the Reproductive Neuroendocrine System During Early Development in Zebrafish

BPA-induced disruption of muscle development and larval metamorphosis in the mussel Mytilus coruscus

Bisphenol A (BPA) has been found in aquatic environments worldwide, raising concerns about its potentially harmful effects, particularly during the early stages of organismal development. In this study, exposure to BPA significantly inhibited the development of Mytilus coruscus larvae and led to abnormal muscle development, characterized by a reduction in adductor muscle size and a decrease in the branching of velum retractor muscles. BPA exposure impaired larval metamorphosis, with reduced metamorphosis rates at 0.01 and 0.1 μg/mL concentrations. Inhibition of velum retractor muscle degeneration and a substantial reduction in the size of adductor muscles were observed, particularly at BPA concentrations of 3 and 5 μg/mL. BPA exposure significantly inhibited the expression of muscle growth-related genes, MHC-2560 and MHC-1792, with suppression observed at multiple stages, indicating impaired muscle development. Transcriptomic analysis showed that BPA exposure significantly affected normal physiological processes in larvae. qPCR analysis confirmed the up-regulation of genes involved in autophagy, the AMPK pathway, and detoxification, alongside the down-regulation of genes associated with apoptosis, hedgehog signaling, and neuroendocrine signaling. These findings highlight the ecological risks of BPA, as environmentally relevant concentrations disrupt critical developmental processes, including muscle degeneration during larval metamorphosis, which are essential for the survival and population dynamics of marine bivalves. BPA exposure was found to negatively impact muscle development by inhibiting the expression of genes critical for muscle growth, leading to abnormal muscle morphology. The molecular mechanisms of BPA toxicity provide important insights into its broader impact on marine ecosystems, especially during early development.

Developmental neurotoxicity of bisphenol F and bisphenol S in animal model systems: A literature review

Neurodevelopmental disorders have complex etiologies, stemming both from genetic and environmental risk factors, including gestational exposure to bisphenol A (BPA). BPA is an endocrine-disrupting chemical widely used in the synthesis of plastics and epoxy-resins. In 2012, the Food and Drug Administration issued a ban on the use of BPA in certain baby and childhood products, which contributed to the proliferation of BPA-free products. To make products without BPA, plastic and epoxy manufacturers often use chemical analogs, including bisphenol F (BPF) and bisphenol S (BPS). However, the structural and biochemical similarities BPF and BPS share with BPA suggest they may have similar molecular and cellular impacts on the developing nervous system, despite consumers generally regarding BPA-free products as safer alternatives. In this review, we synthesized all available peer-reviewed primary literature to date reporting on the neurodevelopmental impacts of BPF and/or BPS in animal models. In total, 61 papers were identified as relevant to the topic, including evaluation of BPF- and BPS-associated neurodevelopmental phenotypes such as changes in neurodevelopmental gene expression, the proliferation and differentiation of neural stem cells, synaptogenesis, central nervous system morphology, neuronal cell death, and behavior. Though less extensively studied than BPA, the collective works described here indicate that BPF and BPS can act as developmental neurotoxicants in animal models, urging further mechanistic and epidemiological analyses of these bisphenol analogs, as well as a reconsideration by regulatory agencies of policies surrounding their usage.

The deleterious effect of bisphenol S on early embryo development of mice

PURPOSE

Increasing levels of infertility in Western countries has drawn ever more scientific attention to the role in this trend of endocrine disruptors, such as bisphenol A, a substance now banned in some cases and some countries. Because this substance has been replaced by the structurally similar bisphenol S (BPS), this study focused on the effects of the latter on early mice embryo development.

METHODS

Cultures of CD1 mice embryos with varying concentrations of BPS were compared with control blank cultures in order to examine the survival rate of embryos according to BPS concentration and culture day.

RESULTS

The administration of BPS at any dose (1, 10, and 100 pg/ml) in cultures of mice embryos led to a significant decrease in their survival rate. The negative effect of BPS was seen to start early (day 1 of experiment), even with the lowest employed dose (1 pg/ml).

CONCLUSIONS

This is, to the best of our knowledge, the first study to investigate the impact of BPS on the survival rate of mice embryos. In this study, potential adverse effects of BPS on early CD1 mice embryo development with regard to survival rate have been identified. Dose of BPS, timing of BPS administration, and time duration of exposure play a critical role in the decrease of mice embryo survival rate as compared to control cultures. These findings raise concerns regarding the safety of BPS and highlight the need for further research into the effect of this substance on human embryos.

Temporal and geographic variability of bisphenol levels in humans: A systematic review and meta-analysis of international biomonitoring data

INTRODUCTION

Bisphenols are endocrine-disrupting chemicals known to contribute to chronic disease across the lifespan. With increased awareness of their health effects, changes in regulation and health behaviors have contributed to reductions in urinary bisphenol A (BPA) levels in the United States, Canada, and Europe. However, global trends in bisphenols outside these regions, especially bisphenol S (BPS) exposure, have been less studied.

AIM

We examine trends in urinary BPA and BPS concentration in non-occupationally exposed populations, where representative data at a country level is unavailable.

METHODS

We systematically reviewed studies published between 2000 and 2023 that included urinary bisphenol concentrations. We examined BPA and BPS concentration changes by sampling year, controlling for region, age, and pregnancy status, with and without a quadratic term and geometric mean, via mixed-effects meta-regression models with a random intercept and sensitivity analysis. We identified heterogeneity using Cochran's Q-statistic, I2 index, and funnel plots.

RESULTS

The final analytic sample consisted of 164 studies. We observed positive non-linear associations between time and BPA concentration internationally (beta: 0.02 ng/mL/year2, 95% CI: [0.01, 0.03]) and in Eastern and Pacific Asia (beta: 0.03 ng/mL/year2, 95% CI: [0.02, 0.05]). We also observed non-linear associations of time with both BPA and BPS concentrations in the Middle East and South Asia (beta: 0.13 ng/mL/year2, 95% CI: [0.01, 0.25] and beta: 0.29 ng/mL/year2, 95% CI: [-0.50, -0.08], respectively). In the sensitivity analyses excluding studies with geometric or arithmetic mean values, each displayed significant shifts from the main findings with some consistent outcomes occurring internationally and/or in specific regions. Heterogeneity was high across studies, suggesting possible bias in our estimations.

CONCLUSIONS

Our findings provide evidence for concern about increasing population exposure to BPA and BPS. Further studies estimating attributable disease burden and costs at regional and global levels are warranted to show these chemicals' impact on population health and economies.

Long-term exposure to environmentally relevant Bisphenol-A levels affects growth, swimming, condition factor, sex ratio and histology of juvenile zebrafish

Bisphenol A (BPA) is an environmental estrogen which perturbs hormone signaling pathways adversely affecting aquatic organisms. To evaluate the impact of developmental exposure to long term yet environmentally relevant low doses of BPA, wild-type juvenile zebrafish of 35 days post fertilization were treated with BPA (1 and 10 µg/L), treatment control (0.5% v/v methanol) and control for 60 days. Both BPA treatments led to significantly increased morality overtime. Length increment and specific growth rates became significantly high in BPA exposed zebrafish overtime. Obesogenic property of BPA was not evident with longexposure to low BPA doses. A significantly high and BPA dose-dependent female-biased sex ratios were observed following the juvenile exposure. Significantly low swimming speed was recorded in the fish of both BPA-treated tanks than that of control. Condition factor was significantly low in BPA exposed fish indicating the poor-wellness. There were numerous histopathological alterations of gonads, liver and kidney indicating impacts of juvenile exposure in zebrafish. Altered growth, swimming, mortality, feminization and histopathological changes in zebrafish induced by BPA indicate the risks associated with developmental exposures. The findings call for more comprehensive studies to comprehend the ecological risks imposed by low concentrations of environmental estrogens in urban aquatic ecosystems.

Regrettable Substitutes and the Brain: What Animal Models and Human Studies Tell Us about the Neurodevelopmental Effects of Bisphenol, Per- and Polyfluoroalkyl Substances, and Phthalate Replacements

In recent decades, emerging evidence has identified endocrine and neurologic health concerns related to exposure to endocrine-disrupting chemicals (EDCs), including bisphenol A (BPA), certain per- and polyfluoroalkyl compounds (PFASs), and phthalates. This has resulted in consumer pressure to remove these chemicals from the market, especially in food-contact materials and personal care products, driving their replacement with structurally or functionally similar substitutes. However, these "new-generation" chemicals may be just as or more harmful than their predecessors and some have not received adequate testing. This review discusses the research on early-life exposures to new-generation bisphenols, PFASs, and phthalates and their links to neurodevelopmental and behavioral alterations in zebrafish, rodents, and humans. As a whole, the evidence suggests that BPA alternatives, especially BPAF, and newer PFASs, such as GenX, can have significant effects on neurodevelopment. The need for further research, especially regarding phthalate replacements and bio-based alternatives, is briefly discussed.

Associations of prenatal exposure to bisphenols with infant anthropometry: A prospective cohort study

BACKGROUND

Bisphenols (BPs) have been shown to exhibit developmental toxicities. Epidemiological evidence on prenatal BPs exposure and infant growth primarily confined scopes to specific BPs and birth outcomes, with few studies focusing on infant growth and reporting inconsistent findings. The joint effect of prenatal exposure to BPs mixture on infant growth was rarely studied.

OBJECTIVE

This study examined associations of prenatal exposure to individual bisphenol A (BPA) and its analogues (bisphenol F [BPF], bisphenol S [BPS], bisphenol AF [BPAF], and tetrachlorobisphenol A [TCBPA]) and their mixture with infant growth.

METHODS

Urinary concentrations of BPs in pregnant women were quantified. Weight, body mass index, skinfold thickness, and circumference measurements of infants were collected at birth, 6 and 12 months of age, rapid growth and overweight were further defined. Multiple linear regression models and Bayesian kernel machine regression models (BKMR) were used to analyze associations of exposure to individual BPs and BPs mixture with infants' anthropometric measurements, and to identify the important components among mixture. The risks for rapid growth and overweight of each BP were determined using modified Poisson regression models.

RESULTS

A general profile of higher prenatal BPs exposure (mainly BPA, BPF, and BPS) associated with higher anthropometric measurements and higher risks of overweight during infancy was found. We also observed higher risks of rapid growth in infants following prenatal BPs exposure, with risk ratios ranging from 1.46 to 1.91. The joint effect of BPs mixture and single effect of each BP from the BKMR models were consistent with findings from the linear regression models, further suggesting that associations in girls were generally driven by BPA, BPF, or BPS, while in boys mainly by BPF.

CONCLUSION

Prenatal exposure to BPs and their mixture could increase anthropometric measurements of offspring during infancy, with implications of altered growth trajectory in future.

Reproductive and transgenerational toxicity of bisphenol S exposure in pregnant rats: Insights into hormonal imbalance and steroid biosynthesis pathway disruption

Bisphenol S (BPS) is an alternative chemical to bisphenol A commonly used in food packaging materials. It raises concerns due to potential adverse effects on human health. However, limited evidence exists regarding reproductive toxicity from BPS exposure, and the mechanism of associated transgenerational toxicity remains unclear. In this study, pregnant SD rats were exposed to two different doses of BPS (0.05 or 20 mg/kg) from GD6 to PND21. The objective was to investigate reproductive and transmissible toxicity induced by BPS, explore endocrine effects, and uncover potential underlying mechanisms in rats. Perinatal exposure to BPS in the F0 generation significantly decreased the rate of body weight, ovarian organ coefficient, and growth and development of the F1 generation. Notably, these changes included abnormal increases in body weight and length, estrous cycle disruption, and embryonic dysplasia in F1. 4D-DIA proteomic and PRM analyses revealed that exposure to 20 mg/kg group significantly altered the expression of proteins, such as Lhcgr and Akr1c3, within the steroid biosynthetic pathway. This led to elevated levels of FSH and LH in the blood. The hypothalamic-pituitary-ovarian (HPO) axis, responsible for promoting fertility through the cyclic secretion of gonadotropins and steroid hormones, was affected. RT-qPCR and Western blot results demonstrated that the expression of GnRH in the hypothalamus was decreased, the GnRHR in the pituitary gland was decreased, and the expression of FSHβ and LHβ in the pituitary gland was increased. Overall, BPS exposure disrupts the HPO axis, hormone levels, and steroid biosynthesis in the ovaries, affecting offspring development and fertility. This study provides new insights into the potential effects of BPS exposure on the reproductive function of the body and its relevant mechanisms of action.

Effects and mechanisms of bisphenols exposure on neurodegenerative diseases risk: A systemic review

Environmental bisphenols (BPs) pose a global threat to human health because of their extensive use as additives in plastic products. BP residues are increasing in various environmental media (i.e., water, soil, and indoor dust) and biological and human samples (i.e., serum and brain). Both epidemiological and animal studies have determined an association between exposure to BPs and an increased risk of neurodegenerative diseases (e.g., Parkinson's disease, Alzheimer's disease, and amyotrophic lateral sclerosis), including cognitive abnormalities and behavioral disturbances. Hence, understanding the biological responses to different BPs is essential for prevention, and treatment. This study provides an overview of the underlying pathogenic molecular mechanisms as a valuable basis for understanding neurodegenerative disease responses to BPs, including accumulation of misfolded proteins, reduction of tyrosine hydroxylase and dopamine, abnormal hormone signaling, neuronal death, oxidative stress, calcium homeostasis, and inflammation. These findings provide new insights into the neurotoxic potential of BPs and ultimately contribute to a comprehensive health risk evaluation.

Effects of Acute and Developmental Exposure to Bisphenol S on Chinese Medaka (Oryzias sinensis)

Bisphenol S (BPS), one of the substitutes for bisphenol A (BPA), is widely used in various commodities. The BPS concentrations in surface water have gradually increased in recent years, making it a predominant bisphenol analogue in the aquatic environment and raising concerns about its health and ecological effects on aquatic organisms. For this study, we conducted a 96 h acute toxicity test and a 15-day developmental exposure test to assess the adverse effects of BPS exposure in Chinese medaka (Oryzias sinensis), a new local aquatic animal model. The results indicate that the acute exposure of Chinese medaka embryos to BPS led to relatively low toxicity. However, developmental exposure to BPS was found to cause developmental abnormalities, such as decreased hatching rate and body length, at 15 dpf. A transcriptome analysis showed that exposure to different concentrations of bisphenol S often induced different reactions. In summary, environmental concentrations of BPS can have adverse effects on the hatching and physical development of Chinese medaka, and further attention needs to be paid to the potential toxicity of environmental BPS.

Indoor Air Sources of Outdoor Air Pollution: Health Consequences, Policy, and Recommendations: An Official American Thoracic Society Workshop Report

Indoor sources of air pollution worsen indoor and outdoor air quality. Thus, identifying and reducing indoor pollutant sources would decrease both indoor and outdoor air pollution, benefit public health, and help address the climate crisis. As outdoor sources come under regulatory control, unregulated indoor sources become a rising percentage of the problem. This American Thoracic Society workshop was convened in 2022 to evaluate this increasing proportion of indoor contributions to outdoor air quality. The workshop was conducted by physicians and scientists, including atmospheric and aerosol scientists, environmental engineers, toxicologists, epidemiologists, regulatory policy experts, and pediatric and adult pulmonologists. Presentations and discussion sessions were centered on 1) the generation and migration of pollutants from indoors to outdoors, 2) the sources and circumstances representing the greatest threat, and 3) effective remedies to reduce the health burden of indoor sources of air pollution. The scope of the workshop was residential and commercial sources of indoor air pollution in the United States. Topics included wood burning, natural gas, cooking, evaporative volatile organic compounds, source apportionment, and regulatory policy. The workshop concluded that indoor sources of air pollution are significant contributors to outdoor air quality and that source control and filtration are the most effective measures to reduce indoor contributions to outdoor air. Interventions should prioritize environmental justice: Households of lower socioeconomic status have higher concentrations of indoor air pollutants from both indoor and outdoor sources. We identify research priorities, potential health benefits, and mitigation actions to consider (e.g., switching from natural gas to electric stoves and transitioning to scent-free consumer products). The workshop committee emphasizes the benefits of combustion-free homes and businesses and recommends economic, legislative, and education strategies aimed at achieving this goal.

Maternal exposure to bisphenol S reduces anxiety and impairs collective antipredator behavior of male zebrafish (Danio rerio) offspring through dysregulation of their serotonergic system

Bisphenol S (BPS) is a common endocrine-disrupting chemical globally used in several consumer and industrial products. Although previous studies suggested that BPS induces multiple effects in exposed organisms, very little is known about its intergenerational effect on offspring behavior and/or the potential underlying mechanisms. To this end, adult female zebrafish Danio rerio were exposed to BPS (0, 10, 30 µg/L) and 1 µg/L of 17-β-estradiol (E2) as a positive control for 60 days. Afterwards, female fish were bred with untreated males, and their offspring were raised to 6 months old in control water. Maternal exposure to BPS decreased male offspring anxiety and antipredator behaviors while boldness remained unaffected. Specifically, maternal exposure to 10 and 30 µg/L BPS and 1 µg/L E2 were found to impact male offspring anxiety levels as they decreased the total time that individuals spent in the dark zone in the light/dark box test and increased the total track length in the center of the open field test. In addition, maternal exposure to all concentrations of BPS and E2 disrupted antipredator responses of male offspring by decreasing shoal cohesion in the presence of chemical alarm cues derived from conspecifics, which communicated high risk. To elucidate the possible molecular mechanism underlying these neuro-behavioral effects of BPS, we assessed the serotonergic system via changes in mRNA expression of serotonin receptors, including the 5-HT1A, 5-HT1B, and 5-HT1D subtypes, the serotonin transporter and monoamine oxidase (MAO). The impaired anxiety and antipredator responses were associated with reduced levels of 5-HT1A subtype and MAO mRNA expression within the brain of adult male offspring. Collectively, the results of this study demonstrate that maternal exposure to environmental concentrations of BPS can interfere with the serotonergic signaling pathway in the developing brain, subsequently leading to the onset of a suite of behavioral deficits in adult offspring.

Bisphenol A alters retinal morphology, visually guided behavior, and thyroid hormone levels in zebrafish larvae

Bisphenols are industrial chemicals that are produced in large quantities and have been detected in all parts of the environment as well as in a multitude of different organisms including humans and fish. Several bisphenols, such as bisphenol A (BPA) and bisphenol F, have been shown to disrupt endocrine systems thereby affecting development and reproduction. While numerous studies investigated the effect of bisphenols on estrogen signaling, their impact on the thyroid hormone system (THS), which is vital for neurodevelopment including sensory development, has been explored to a lesser extent. The present work selected BPA as a representative for structurally similar bisphenols and assessed its impact on the THS as well as sensory development and function in zebrafish. To this end, zebrafish were exposed to BPA until up to 8 days post fertilization (dpf) and thyroid hormone levels, eye morphology, and sensory-mediated behaviors were analyzed. Zebrafish larvae exposed to BPA showed altered retinal layering, decreased motility across varying light conditions, and a loss of responsiveness to red light. Furthermore, whole-body levels of the thyroid hormones thyroxine (T4) and 3,5-diiodothyronine (3,5-T2) were significantly decreased in 5 dpf zebrafish. Taken together, BPA disrupted THS homeostasis and compromised visual development and function, which is pivotal for the survival of fish larvae. This work underlines the necessity for ongoing research on BPA and its numerous substitutes, particularly concerning their effects on the THS and neurodevelopment, to ensure a high level of protection for the environment and human health.

Thyroid-gonadal hormonal interplay in zebrafish exposed to sodium perchlorate: Implications for reproductive health

Perchlorate, a widespread environmental contaminant originating from various industrial applications, agricultural practices, and natural sources, poses potential risks to ecosystems and human health. While previous studies have highlighted its influence on the thyroid endocrine system and its impact on gonadal maturation, reproduction, and sex hormone synthesis, the specific interplay between thyroid and steroid hormones, in this context, remains largely unexplored. Therefore, this study was undertaken to investigate the adverse effects and underlying mechanisms triggered by exposure to sodium perchlorate (SP) on reproductive endocrine activity in zebrafish. For 21 d, the fish were exposed to test SP concentrations (0, 3, 30, 300 mg/L), which were determined based on the exposure concentrations that induced various toxic effects in the fish, considering naturally occurring concentrations. Exposure to SP, except at 3 mg/L in males, significantly decreased the production of thyroid hormone (TH) in both female and male zebrafish. Moreover, gonadal steroid levels were markedly reduced in both sexes. The expression of hepatic vitellogenin (VTG) mRNA in female zebrafish was significantly decreased, whereas aromatase activity in male zebrafish was significantly elevated in the SP exposure groups. The reduced levels of THs and gonadal steroid hormones were strongly correlated. Abnormal responses to SP exposure led to reduced reproductive success in the 300 mg/L SP exposure group. These findings indicate that prolonged and continuous exposure to a specific concentration of SP may lead to long-term reproductive problems in zebrafish, primarily through hormonal imbalances and suppression of hepatic VTG mRNA expression.

Study on reproductive endocrine disturbance and DNA damage mechanism of female Ruditapes philippinarum under Benzo[a]pyrene stress

The reproductive toxicity of polycyclic aromatic hydrocarbons (PAHs) in aquatic organisms has attracted increasing attention from scholars. Currently, research in this field primarily focuses on vertebrates such as zebrafish and other model species. However, there is still a significant knowledge gap in the toxicity of PAHs to invertebrates and its potential mechanisms. Benzo[a]pyrene (B[a]P) is one of the most representative PAHs. In this study, female Ruditapes philippinarum (R. philippinarum) was treated with B[a]P concentrations of 0, 0.8, 4, and 20 μg/L to investigate reproductive indicators in the proliferative, growth, mature, and spawn stages. Transcriptomics was used to investigate the expression of genes associated with the reproductive endocrine system, DNA repair, autophagy, apoptosis, and ovarian development at different reproductive stages. Our results suggested that B[a]P disrupted the endocrine system by interfering with the production of steroid hormones and the transmission of estrogen signals in female R. philippinarum. The structure of the ovarian DNA duplex is severely damaged under the stress of B[a]P, and a series of cellular responses caused by DNA damage are also interfered. Additionally, we observed a reduction in the gonadosomatic index (GSI) and mature oocytes numbers after B[a]P exposed. Tissue section indicated that severe damage to the ovarian structure at mature and spawn stages. In conclusion, this study combined transcriptomic and toxicological to explore the negative effects on ovarian development induced by B[a]P, focusing on reproductive endocrine disturbance and DNA damage.

Prenatal Phenol and Paraben Exposures and Adverse Birth Outcomes: A Prospective Analysis of U.S. Births

BACKGROUND

Synthetic chemicals are increasingly being recognized for potential independent contributions to preterm birth (PTB) and low birth weight (LBW). Bisphenols, parabens, and triclosan are consumer product chemicals that act via similar mechanisms including estrogen, androgen, and thyroid disruption and oxidative stress. Multiple cohort studies have endeavored to examine effects on birth outcomes, and systematic reviews have been limited due to measurement of 1-2 spot samples during pregnancy and limited diversity of populations.

OBJECTIVE

To study the effects of prenatal phenols and parabens on birth size and gestational age (GA) in 3,619 mother-infant pairs from 11 cohorts in the NIH Environmental influences on Child Health Outcomes program.

RESULTS

While many associations were modest and statistically imprecise, a 1-unit increase in log10 pregnancy averaged concentration of benzophenone-3 and methylparaben were associated with decreases in birthweight, birthweight adjusted for gestational age and SGA. Increases in the odds of being SGA were 29% (95% CI: 5%, 58%) and 32% (95% CI: 3%, 70%), respectively. Bisphenol S in third trimester was also associated with SGA (OR 1.52, 95% CI 1.08, 2.13). Associations of benzophenone-3 and methylparaben with PTB and LBW were null. In addition, a 1-unit increase in log10 pregnancy averaged concentration of 2,4-dichlorophenol was associated with 43% lower (95% CI: -67%, -2%) odds of low birthweight; the direction of effect was the same for the highly correlated 2,5-dichlorophenol, but with a smaller magnitude (-29%, 95% CI: -53%, 8%).

DISCUSSION

In a large and diverse sample generally representative of the United States, benzophenone-3 and methylparaben were associated with lower birthweight as well as birthweight adjusted for gestational age and higher odds of SGA, while 2,4-dichlorophenol. These associations with smaller size at birth are concerning in light of the known consequences of intrauterine growth restriction for multiple important health outcomes emerging later in life.

Influence of phthalate and non-phthalate plasticizers on reproductive endocrine system-related gene expression profiles in Japanese medaka (Oryzias latipes)

Plasticizers containing phthalates have the potential to alter endocrine function in vertebrates. While non-phthalate plasticizers were previously considered to be environmentally friendly and safe, our research team discovered that bis-(2-ethylhexyl) adipate (DEHA) and acetyl tributyl citrate (ATBC) disrupt thyroid hormones in Japanese medaka (Oryzias latipes). We assessed reproductive- and estrogen-responsive gene expression patterns in Japanese medaka to determine whether the phthalate plasticizers bis-(2-ethylhexyl) phthalate (DEHP, positive control) and the non-phthalate plasticizers DEHA and ATBC disrupt endocrine signaling. The results showed that the levels of choriogenin H (chgH) and vitellogenin (vtg) genes increased after exposure to DEHP and ATBC, suggesting that these plasticizers may have estrogenic activity. Exposure to DEHP and DEHA resulted in the upregulation of kisspeptin (kiss), gonadotropin-releasing hormone (gnrh), and follicle-stimulating hormone beta (fshβ) genes, suggesting that these plasticizers may interfere with reproductive function. To the best of our knowledge, this is the first study to demonstrate that the non-phthalate plasticizers DEHA and ATBC can disrupt reproduction-related hormonal activity in fish.

Effects of bisphenol F, bisphenol S, and bisphenol AF on cultured human osteoblasts

Bisphenol A (BPA) analogs, like BPA, could have adverse effects on human health including bone health. The aim was to determine the effect of BPF, BPS and BPAF on the growth and differentiation of cultured human osteoblasts. Osteoblasts primary culture from bone chips harvested during routine dental work and treated with BPF, BPS, or BPAF for 24 h at doses of 10-5, 10-6, and 10-7 M. Next, cell proliferation was studied, apoptosis induction, and alkaline phosphatase (ALP) activity. In addition, mineralization was evaluated at 7, 14, and 21 days of cell culture in an osteogenic medium supplemented with BP analog at the studied doses. BPS treatment inhibited proliferation in a dose-dependent manner at all three doses by inducing apoptosis; BPF exerted a significant inhibitory effect on cell proliferation at the highest dose alone by an increase of apoptosis; while BPAF had no effect on proliferation or cell viability. Cell differentiation was adversely affected by treatment with BPA analogs in a dose-dependent, observing a reduction in calcium nodule formation at 21 days. According to the results obtained, these BPA analogs could potentially pose a threat to bone health, depending on their concentration in the organism.

Different types of bisphenols alter ovarian steroidogenesis: Special attention to BPA

Endocrine disruptors such as bisphenol A (BPA) and some of its analogues, including BPS, BPAF, and BPE, are used extensively in the manufacture of plastics. These synthetic chemicals could seriously alter the functionality of the female reproductive system. Although the number of studies conducted on other types of bisphenols is smaller than the number of studies on BPA, the purpose of this review study was to evaluate the effects of bisphenol compounds, particularly BPA, on hormone production and on genes involved in ovarian steroidogenesis in both in vitro (human and animal cell lines) and in vivo (animal models) studies. The current data show that exposure to bisphenol compounds has adverse effects on ovarian steroidogenesis. For example, BPA, BPS, and BPAF can alter the normal function of the hypothalamic-pituitary-gonadal (HPG) axis by targeting kisspeptin neurons involved in steroid feedback signals to gonadotropin-releasing hormone (GnRH) cells, resulting in abnormal production of LH and FSH. Exposure to BPA, BPS, BPF, and BPB had adverse effects on the release of some hormones, namely 17-β-estradiol (E2), progesterone (P4), and testosterone (T). BPA, BPE, BPS, BPF, and BPAF are also capable of negatively altering the transcription of a number of genes involved in ovarian steroidogenesis, such as the steroidogenic acute regulatory protein (StAR, involved in the transfer of cholesterol from the outer to the inner mitochondrial membrane, where the steroidogenesis process begins), cytochrome P450 family 17 subfamily A member 1 (Cyp17a1, which is involved in the biosynthesis of androgens such as testosterone), 3 beta-hydroxysteroid dehydrogenase enzyme (3β-HSD, involved in the biosynthesis of P4), and cytochrome P450 family 19 subfamily A member 1 (Cyp19a1, involved in the biosynthesis of E2). Exposure to BPA, BPB, BPF, and BPS at prenatal or prepubertal stages could decrease the number of antral follicles by activating apoptosis and autophagy pathways, resulting in decreased production of E2 and P4 by granulosa cells (GCs) and theca cells (TCs), respectively. BPA and BPS impair ovarian steroidogenesis by reducing the function of some important cell receptors such as estrogens (ERs, including ERα and ERβ), progesterone (PgR), the orphan estrogen receptor gamma (ERRγ), the androgen receptor (AR), the G protein-coupled estrogen receptor (GPER), the FSHR (follicle-stimulating hormone receptor), and the LHCGR (luteinizing hormone/choriogonadotropin receptor). In animal models, the effects of bisphenol compounds depend on the type of animals, their age, and the duration and dose of bisphenols, while in cell line studies the duration and doses of bisphenols are the matter.

Estrogenic and non-estrogenic effects of bisphenol A and its action mechanism in the zebrafish model: An overview of the past two decades of work

Bisphenol A (BPA) is the most simple and predominant component of the Bisphenol family. BPA is widely present in the environment and the human body as a result of its extensive usage in the plastic and epoxy resins of consumer goods like water bottles, food containers, and tableware. Since the 1930s, when BPA's estrogenic activity was first observed, and it was labeled as a "mimic hormone of E2", studies on the endocrine-disrupting effects of BPA then have been widely conducted. As a top vertebrate model for genetic and developmental studies, the zebrafish has caught tremendous attention in the past two decades. By using the zebrafish, the negative effects of BPA either through estrogenic signaling pathways or non-estrogenic signaling pathways were largely found. In this review, we tried to draw a full picture of the current state of knowledge on the estrogenic and non-estrogenic effects of BPA with their mechanisms of action through the zebrafish model of the past two decades, which may help to fully understand the endocrine-disrupting effects of BPA and its action mechanism, and give a direction for the future studies.

Exposure to bisphenol A alternatives bisphenol AF and fluorene-9-bisphenol induces gonadal injuries in male zebrafish

Bisphenol A (BPA), present in many household products, can damage the male reproductive system. Accordingly, we summarized urine samples from 6921 human in National Health and Nutrition Examination Survey and found urinary BPA levels were inversely linked with blood testosterone in the children group. Currently, BPA replacements, such as fluorene-9-bisphenol (BHPF) and Bisphenol AF (BPAF), have been introduced to produce "BPA-free" products. Here we demonstrated that BPAF and BHPF could induce delayed gonadal migration and reduce the number of progenitors of germ cell lineage in zebrafish larvae. A close receptor analysis study reveals that BHPF and BPAF can strongly bind to androgen receptors, leading to the downregulation of meiosis-related genes and the overexpression of inflammatory markers. Furthermore, BPAF and BPHF can induce activation of the gonadal axis via negative feedback, leading to the hypersecretion of some upstream hormones and an increase in the expression of upstream hormone receptors. Our findings call for further research on the toxicological effects of BHPF and BPAF on human health and recommend that BPA replacements be investigated for anti-estrogenic action.

Effects of non-phthalate plasticizer bis(2-ethylhexyl) sebacate (DEHS) on the endocrine system in Japanese medaka (Oryzias latipes)

Water pollution due to plasticizers is one of the most severe environmental problems worldwide. Phthalate plasticizers can act as endocrine disruptors in vertebrates. In this study, we investigated whether the non-phthalate bis(2-ethylhexyl) sebacate (DEHS) plasticizer can act as an endocrine disruptor by evaluating changes in the expression levels of thyroid hormone-related, reproduction-related, and estrogen-responsive genes of Japanese medaka (Oryzias latipes) exposed to the plasticizer. Following the exposure, the gene expression levels of thyroid-stimulating hormone subunit beta (tshβ), deiodinase 1 (dio1), and thyroid hormone receptor alpha (trα) did not change. Meanwhile, DEHS suppressed dio2 expression, did not induce swim bladder inflation, and eventually reduced the swimming performance of Japanese medaka. These findings indicate that DEHS can potentially disrupt the thyroid hormone-related gene expression and metabolism of these fish. However, exposure to DEHS did not induce changes in the gene expression levels of kisspeptin 1 (kiss1), gonadotropin-releasing hormone (gnrh), follicle-stimulating hormone beta (fshβ), luteinizing hormone beta (lhβ), choriogenin H (chgH), and vitellogenin (vtg) in a dose-dependent manner. This is the first report providing evidence that DEHS can disrupt thyroid hormone-related metabolism in fish.

The Pediatrician's Role in Protecting Children from Environmental Hazards

Children suffer disproportionately from disease and disability due to environmental hazards, for reasons rooted in their biology. The contribution is substantial and increasingly recognized, particularly due to ever-increasing awareness of endocrine disruption. Regulatory actions can be traced directly to reductions in toxic exposures, with tangible benefits to society. Deep flaws remain in the policy framework in industrialized countries, failing to offer sufficient protection, but are even more limited in industrializing nations where the majority of chemical production and use will occur by 2030. Evidence-based steps for reducing chemical exposures associated with adverse health outcomes exist and should be incorporated into anticipatory guidance.

[Bisphenol A and breast cancer: State of knowledge and meta-analysis]

INTRODUCTION

Bisphenol A is an endocrine disruptor used in the composition of food containers. It was partially banned in France in 2015 and classified as a "very high-risk substance" in 2017. Bisphenol A's carcinogenic effects have been demonstrated in animal testing. Bisphenol A acts through estrogen-dependent and estrogen-independent pathways. It induces epigenetic changes and impacts the microenvironment of the mammary gland. However, the role of bisphenol A exposure in the development of breast cancer in humans remains controversial. This study documents the current thinking on bisphenol A with an analysis of the mechanisms and a meta-analysis.

MATERIALS AND METHODS

A literature review and a statistical analysis of linear regression type, with the creation of a Forest plot, were used to perform the meta-analysis of 9 studies including 10,695 patients.

RESULTS

Nine case-control studies, published between 1990 and 2021, investigating the association between breast cancer and mean urinary, blood or tissue bisphenol A levels were selected. The meta-analysis did not find a significant association between bisphenol A exposure and the development of breast cancer with an OR=(1 IC95% [0.92-1.08]).

DISCUSSION

This meta-analysis does not show a link between breast cancer and bisphenol A exposure. Nevertheless, the analysis of a pathogenic link between bisphenol A and breast cancer requires additional cohort studies to conclude because of methods of available studies.

Bisphenol A enhances apoptosis, fibrosis, and biochemical fluctuations in the liver of adult male rats with possible regression after recovery

Bisphenol A (BPA) is an environmental contaminant that might be harmful. Human exposure to BPA can occur during the fetal and postnatal periods and extends throughout life. This study aimed to estimate the effects of oral administration of BPA on rat liver and assess the possibility of recovery after cessation. Adult male albino rats were orally administered with BPA (50 mg/kg body weight) for 8 weeks, and then one group was left to recover for 4 weeks. Histological, immunohistochemical, biochemical, and quantitative real-time polymerase chain reaction assessments were performed. Loss of hepatic architecture, vascular dilatation congestion, and exudation, as well as cellular vacuolation, fat accumulation, and pyknotic nuclei were detected. Furthermore, inflammatory infiltration, localized metaplasia, and excessive collagen deposition in the portal triad were observed. Expression of Bcl-2-associated X protein and transforming growth factor beta 1 was prominent, denoting apoptosis and fibrosis. After the administration of BPA, serum levels of alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, total bilirubin, cholesterol, triglycerides, and low-density lipoproteins were enhanced. Additionally, total protein, albumin, and high-density lipoproteins decreased. After a recovery for 4 weeks, hepatic cellular and vascular pathologies returned to normal, except for some inflammatory infiltration. Regarding biochemical affection, most of the parameters were directed toward normal during recovery. However, most of them were still significantly different from controls. This explored BPA hepatotoxicity from structural and functional aspects, and the possible spontaneous reversibility was confirmed. However, the precise mechanisms underlying hepatotoxicity or recovery need more in-depth investigations.

Parental transfer of an antibiotic mixture induces cardiotoxicity in early life-stage zebrafish: A cross-generational study

Antibiotic residues in the aquatic environment have been shown to induce significant adverse effects on the early-life stage development of aquatic organisms, though the underlying molecular mechanisms of these effects have not been well characterized. In this study, we performed global mRNA-miRNA sequencing, canonical pathway analyses, morphological, physiological, immunohistochemical, and behavioral analyses to comprehensively assess the cross-generational cardiotoxicity and mechanisms of antibiotic mixtures in zebrafish. Following parental treatment to 1 and 100 μg/L antibiotic mixtures (15 of the most commonly detected antibiotics) for 150 days, all 15 assessed antibiotics were detected in the F1 eggs, indicating the cross-generational transfer of antibiotics. Global mRNA-miRNA sequencing functional analysis predicted cardiotoxicity in the F1 generation by using the F1 whole fish. Consistent with canonical pathway analyses, significant cardiotoxicity was observed in F1 larvae, as well as the apoptosis of cardiac cells. Furthermore, let-7a-5p regulated the cardiac hypertrophy signaling pathway, suggesting mechanisms of miRNA of let-7 family mediating cross-generational cardiotoxicity of antibiotics in zebrafish. This study lays some groundwork for developing interventions to prevent parental exposure to environmental pollutants such as antibiotics from adversely affecting offspring development.

Long-term BPA exposure leads to bone malformation and abnormal expression of MAPK/Wnt/FoxO signaling pathway genes in zebrafish offspring

Bisphenol A (BPA) is one of the world's most widely used plasticizer, and its hazardous impacts have been well studied. However, few studies focused on the effects of parental long-term BPA exposure on the bone development of offspring. In the present study, the bone development of offspring was studied following long-term exposure of parental zebrafish to environmentally relevant 15 and 225 µg/L BPA. The results showed that BPA increased the mortality and deformity rate of offspring and caused craniofacial deformities characterized by changes in various cartilage angles and lengths. The alizarin red and calcein staining showed that BPA could delay bone mineralization and reduce bone mass accumulation. The results of acridine orange staining indicated that BPA induced apoptosis of the skull. The degree of harm of BPA presented a dose-dependent pattern. The results of the comparative transcriptome showed that there were 380 different expression genes (DEGs) in the 15 µg/L BPA group, and 645 DEGs in the 225 µg/L BPA group. MAPK/Wnt/FoxO signaling pathway-related genes were significantly down-regulated in the BPA-exposed groups. The present study demonstrates that long-term parental BPA exposure would severely affect cartilage development and bone mineralization of fish offspring, and MAPK/Wnt/FoxO signaling pathways may be involved in this process.

Harbours as unique environmental sites of multiple anthropogenic stressors on fish hormonal systems

Fish development and acclimation to environmental conditions are strongly mediated by the hormonal endocrine system. In environments contaminated by anthropogenic stressors, hormonal pathway alterations can be detrimental for growth, survival, fitness, and at a larger scale for population maintenance. In the context of increasingly contaminated marine environments worldwide, numerous laboratory studies have confirmed the effect of one or a combination of pollutants on fish hormonal systems. However, this has not been confirmed in situ. In this review, we explore the body of knowledge related to the influence of anthropogenic stressors disrupting fish endocrine systems, recent advances (focusing on thyroid hormones and stress hormones such as cortisol), and potential research perspectives. Through this review, we highlight how harbours can be used as "in situ laboratories" given the variety of anthropogenic stressors (such as plastic, chemical, sound, light pollution, and invasive species) that can be simultaneously investigated in harbours over long periods of time.

Maternal exposure to bisphenol S induces neuropeptide signaling dysfunction and oxidative stress in the brain, and abnormal social behaviors in zebrafish (Danio rerio) offspring

Recent studies show that bisphenol S (BPS) induces multiple adverse effects in exposed organisms; however, the maternal effects of BPS exposure remain poorly understood. Here, we expose adult female zebrafish to environmentally relevant concentrations of BPS (0, 1, 10, 30 μg/L) and 1 μg/L of 17-β-estradiol (E2) as a positive control for 60 days. Females were then paired with BPS-unexposed males and their offspring were raised in control water for 6 months. Maternal exposure to BPS was found to alter social behavior and anxiety response in a dose-specific manner in male offspring. Group preferences and social cohesion were significantly reduced by maternal exposure to 1 and 10 μg/L BPS, respectively. Additionally, maternal exposure to 1 and 30 μg/L BPS and E2 decreased offspring stress responses during the novel tank test. The impaired social behavior was associated with elevated arginine-vasotocin (AVT) level as well as with the altered expression of genes involved in AVT signaling pathway (AVT, avpr1aa) and enzymatic antioxidant genes (cat and Mn-sod) in the brain. Collectively, these results suggest that maternal exposure to environmentally relevant concentrations of BPS alters social behavior in zebrafish offspring, which is likely mediated by oxidative stress and disruption of neuropeptide signaling pathways in the brain.

A chronic exposure to bisphenol A reduces sperm quality in goldfish associated with increases in kiss2, gpr54, and gnrh3 mRNA and circulatory LH levels at environmentally relevant concentrations

The bisphenol A (BPA)-disrupted reproductive functions have been demonstrated in male animals. In fish, it has been shown that environmentally relevant concentrations of BPA decrease sperm quality associated with inhibition of androgen biosynthesis. However, BPA effects on neuroendocrine regulation of reproduction to affect testicular functions are largely unknown. In the present study, reproductive functions of hypothalamus and pituitary were studied in mature male goldfish exposed to nominal 0.2, 2.0 and 20.0 μg/L BPA. At 90 d of exposure, sperm volume, velocity, and density and motility were decreased in goldfish exposed to 0.2, 2.0, and 20.0 μg/L BPA, respectively (p < 0.05). At 30 d of exposure, there were no significant changes in circulatory LH levels and mRNA transcripts of kiss1, Kiss2, gpr54, and gnrh3. At 90 d of exposure, circulatory LH levels showed trends toward increases in BPA exposed goldfish, which was significant in those exposed to 2.0 μg/L (P < 0.05). At this time, Kiss2, gpr54, and gnrh3 mRNA levels were increased in goldfish exposed to any concentrations of BPA (p < 0.05). This study shows that BPA-diminished sperm quality was accompanied by an increase in circulatory LH levels associated with increases in mRNA transcripts of upstream neuroendocrine regulators of reproduction in goldfish. Further, this is the first study to report circulatory levels of LH in fish exposed to BPA.

Effects of 17α-Ethinylestradiol (EE2) exposure during early life development on the gonadotropic axis ontogenesis of the European sea bass, Dicentrarchus labrax

Exposure of young organisms to oestrogenic endocrine disrupting chemicals (EDCs) can elicit adverse effects, particularly on the reproductive function. In fish, as in other vertebrates, reproduction is controlled by the neuroendocrine gonadotropic axis, whose components are mainly regulated by sex steroids and may then be targets for EDCs. In the present study, we investigated the effects of a xenoestrogen exposure on the ontogenesis of the gonadotropic axis in European sea bass. After exposure of hatching larvae for 8 days to 17α-ethinylestradiol (EE2) (0.5 nM and 50 nM), gene expression for kisspeptins (kiss1, kiss2), gonadotropin-releasing hormones (gnrh1, gnrh2, gnrh3), gonadotropin beta subunits (lhβ and fshβ) and brain type aromatase (cyp19a1b) were measured using quantitative real-time PCR. Our results demonstrate that EE2 strongly stimulated the expression of brain type aromatase (cyp19a1b) in sea bass larvae. In addition, EE2 exposure also affected the mRNA levels of kiss1, gnrh1 and gnrh3 by inducing a downregulation of these genes during the early developmental stages, while no effect was seen in gnrh2, lhβ and fshβ. These results reinforce the idea that the larval development is a sensitive critical period in regard to endocrine disruption and that the gonadotropic axis in the developing sea bass is sensitive to xenoestrogen exposure.

Bisphenol A Exposure Induces Sensory Processing Deficits in Larval Zebrafish during Neurodevelopment

Because of their ex utero development, relatively simple nervous system, translucency, and availability of tools to investigate neural function, larval zebrafish are an exceptional model for understanding neurodevelopmental disorders and the consequences of environmental toxins. Furthermore, early in development, zebrafish larvae easily absorb chemicals from water, a significant advantage over methods required to expose developing organisms to chemical agents in utero Bisphenol A (BPA) and BPA analogs are ubiquitous environmental toxins with known molecular consequences. All humans have measurable quantities of BPA in their bodies. Most concerning, the level of BPA exposure is correlated with neurodevelopmental difficulties in people. Given the importance of understanding the health-related effects of this common toxin, we have exploited the experimental advantages of the larval zebrafish model system to investigate the behavioral and anatomic effects of BPA exposure. We discovered that BPA exposure early in development leads to deficits in the processing of sensory information, as indicated by BPA's effects on prepulse inhibition (PPI) and short-term habituation (STH) of the C-start reflex. We observed no changes in locomotion, thigmotaxis, and repetitive behaviors (circling). Despite changes in sensory processing, we detected no regional or whole-brain volume changes. Our results show that early BPA exposure can induce sensory processing deficits, as revealed by alterations in simple behaviors that are mediated by a well-defined neural circuit.

Role of endocrine disruption in toxicity of 6-benzylaminopurine (6-BA) to early-life stages of Zebrafish

6-benzylaminopurine (6-BA), classified as a "plant hormone", is an important ingredient in production of "toxic bean sprouts". Although there is no direct evidence of adverse effects, its hazardous effects have received some attention and aroused furious debate between proponents and environmental regulators. In this study, potential adverse effects of 6-BA were investigated by exposing zebrafish in vivo to 0.2 - 25 mg 6-BA/L. Results indicated that, when exposure was limited to early-life stage (4-36 hpf), 20 mg 6-BA/L caused early hatching, abnormal spontaneous movement, and precocious hyperactivity in zebrafish embryos/larvae. While under a continuous exposure regime, 6-BA at 0.2 mg/L was able to cause hyperactive locomotion and transcription of genes related to neurogenesis (gnrh3 and nestin) and endocrine systems (cyp19a and fshb) in 5 dpf larvae. Quantification by use of LC/MS indicated bioaccumulation of 6-BA in zebrafish increased when exposed to 0.2 or 20 mg 6-BA/L. These results suggested that 6-BA could accumulate in aquatic organisms and disrupt neuro-endocrine systems. Accordingly, exposure to 0.2 mg 6-BA/L increased production of estradiol (E2) and consequently E2/T ratio in zebrafish larvae, which directly indicated 6-BA is estrogenic. In silico simulations demonstrated potential for binding of 6-BA to estrogen receptor alpha (ERa) and cytochrome P450 aromatase (CYP19A). Therefore, induction of estrogenic effects, via potential interactions with hormone receptors or disturbance of downstream transcription signaling, was possible mechanism underlying the toxicity of 6-BA. Taken together, these findings demonstrate endocrine disrupting properties of 6-BA, which suggest concerns about risks posed to endocrine systems.

The Role of Estrogen and Thyroid Hormones in Zebrafish Visual System Function

Visual system development is a highly complex process involving coordination of environmental cues, cell pathways, and integration of functional circuits. Consequently, a change to any step, due to a mutation or chemical exposure, can lead to deleterious consequences. One class of chemicals known to have both overt and subtle effects on the visual system is endocrine disrupting compounds (EDCs). EDCs are environmental contaminants which alter hormonal signaling by either preventing compound synthesis or binding to postsynaptic receptors. Interestingly, recent work has identified neuronal and sensory systems, particularly vision, as targets for EDCs. In particular, estrogenic and thyroidogenic signaling have been identified as critical modulators of proper visual system development and function. Here, we summarize and review this work, from our lab and others, focusing on behavioral, physiological, and molecular data collected in zebrafish. We also discuss different exposure regimes used, including long-lasting effects of developmental exposure. Overall, zebrafish are a model of choice to examine the impact of EDCs and other compounds targeting estrogen and thyroid signaling and the consequences of exposure in visual system development and function.

Sex-specific effects of bisphenol S with tissue-specific responsiveness in adult zebrafish: The antiandrogenic and antiestrogenic effects

This study investigates the adverse effects and the associated underlying mechanism of bisphenol S (BPS) exposure on reproductive endocrine activity in adult zebrafish. Fish were exposed for 21 days to different BPS concentrations (0, 8, 40, and 200 µg/mL) determined via the lowest observed adverse effect level (LOAEL, i.e., < EC₁₅ = 250 µg/mL) for zebrafish embryos. Exposure to 200 µg/mL BPS in female zebrafish in the absence of vitellogenic oocytes or the presence of degenerated oocytes in the ovary significantly decreased the biosynthesis of hepatic vitellogenin (VTG) mRNA, while hepatic VTG mRNA in male fish abundance was significantly elevated (P < 0.05). The levels of gonadal steroids were significantly increased in female zebrafish, while in male zebrafish, the levels of endogenous androgens were reduced (P < 0.05). However, the activities of 17β-estradiol and aromatase in male zebrafish were significantly elevated in all BPS exposure groups in male zebrafish (P < 0.05). Interestingly, thyroid hormone levels and residual whole-body BPS levels increased in female and male zebrafish with increasing exposure concentrations. A novel finding is that the response to BPS depends on zebrafish sex and tissue-specific responsiveness to the accumulation of BPS, suggesting that BPS may cause long-term environmental problems in adult zebrafish through tissue-specific suppression and hormonal imbalance.

Teratogenicity and toxicity of the new BPA alternative TMBPF, and BPA, BPS, and BPAF in chick embryonic development

Bisphenol A (BPA) is a widely known, yet controversial reproductive toxin, capable of inducing reproductive, developmental, and somatic growth defects across species. Due to scientific findings and public concern, companies have developed BPA alternatives remarkably similar to BPA. However, these alternatives have had much less testing and oversight, yet they are already being mass-produced and used across industries from plastics to food-contact coatings. The newest one, tetramethyl bisphenol F (TMBPF), is the least well-studied and has never been investigated in embryological models, however it continues to be mass produced and found in various products. Here, we used the chicken embryotoxicity screening test to compare the toxicities and potencies of several BPA analogs including TMBPF. We exposed developing chicken (Gallus gallus domesticus) embryos in ovo, from embryonic day 5 to 12 (E5-12), to increasing concentrations of BPA, bisphenol S (BPS), bisphenol AF (BPAF), and TMBPF, from 0.003 to 30 μM, and analyzed their developmental and toxic effects. The bisphenols significantly impaired development, growth, and survival in a dose-dependent manner, even at low, environmentally relevant concentrations of 3-30 nM. There was severely reduced growth and developmental delay, with exposed embryos averaging half the size and weight of control vehicle-treated embryos. The most common and severe dysmorphologies were craniofacial, eye, gastrointestinal, and body pigmentation abnormalities. The bisphenols caused dose-dependent toxicity with the lowest LC₅₀s (lethal concentration with 50% survival) ever demonstrated in chick embryos, at 0.83-2.92 μM. Notably, TMBPF was the second-most toxic and teratogenic of all chemicals tested (rank order of BPAF > TMBPF > BPS > BPA). These results underscore the adverse effects of BPA replacements on early embryo development and may have implications for reproductive health and disease across species, including pregnancy exposures in humans.

Does bisphenol A bioaccumulate on zebrafish? Determination of tissue bisphenol A level

Bisphenol A (BPA) is a high-production-volume industrial chemical mainly used in the production of polycarbonates and epoxy resins utilized in the manufacture of containers, bottles, toys, and medical devices. It has systemic effects as an endocrine disruptor even at low doses. To analyze its quantity in biological materials, sensitive and reproducible methods have to be used. Different doses and duration (90 and 900 μg/L, 24 and 120 h, and 21 days) of BPA exposure to whole body zebrafish were analyzed after specific homogenization of tissue, and then a modified method HPLC was used. The mobile phase was acetonitrile and water using a gradient method of reversed-phase C18 column, and excitation = 227 nm/emission = 313 nm. The calibration curve for BPA using HPLC-fluorescence detection method was between a concentration range of 1 and 1000 ng/mL and linear, and r²  = 0.999. The mean and standard error of mean values were 4.29 ± 1.05, 2.50 ± 0.92, and 2.53 ± 0.68 for control; 10.43 ± 2.61, 11.46 ± 3.24, and 8.55 ± 3.11 for BPA-90 μg/L; and 17.78 ± 4.39, 21.55 ± 4.37, and 25.32 ± 3.25 for BPA-900 μg/L (24 h, 120 h, and 21 days, respectively). Although some statistical significance among dose/time was observed between two different dose-treated groups, statistical significance was not found in dose/time results within the group. However, the positive result of BPA in the control group can be explained by low-dose, chronic exposure or prevalence of endocrine-disrupting chemicals.

Bisphenol A and Its Analogues Deteriorate the Hormones Physiological Function of the Male Reproductive System: A Mini-Review

BPA is identified as an endocrine-disrupting chemical that deteriorates the physiological function of the hormones of the male reproductive system. Bisphenol F (BPF), bisphenol S (BPS), and bisphenol AF (BPAF) are actively explored as substitutes for BPA and are known as BPA analogues in most manufacturing industries. These analogues may demonstrate the same adverse effects as BPA on the male reproductive system; however, toxicological data explaining the male reproductive hormones' physiological functions are still limited. Hence, this mini-review discusses the effects of BPA and its analogues on the physiological functions of hormones in the male reproductive system, focusing on the hypothalamus-pituitary-gonad (HPG) axis, steroidogenesis, and spermatogenesis outcomes. The BPA analogues mainly show a similar negative effect on the hormones' physiological functions, proven by alterations in the HPG axis and steroidogenesis via activation of the aromatase activity and reduction of spermatogenesis outcomes when compared to BPA in in vitro and in vivo studies. Human biomonitoring studies also provide significant adverse effects on the physiological functions of hormones in the male reproductive system. In conclusion, BPA and its analogues deteriorate the physiological functions of hormones in the male reproductive system as per in vitro, in vivo, and human biomonitoring studies.

Recording from an Identified Neuron Efficiently Reveals Hazard for Brain Function in Risk Assessment

Modern societies use a continuously growing number of chemicals. Because these are released into the environment and are taken up by humans, rigorous (but practicable) risk assessment must precede the approval of new substances for commerce. A number of tests is applicable, but it has been very difficult to efficiently assay the effect of chemicals on communication and information processing in vivo in the adult vertebrate brain. Here, we suggest a straightforward way to rapidly and accurately detect effects of chemical exposure on action potential generation, synaptic transmission, central information processing, and even processing in sensory systems in vivo by recording from a single neuron. The approach is possible in an identified neuron in the hindbrain of fish that integrates various sources of information and whose properties are ideal for rapid analysis of the various effects chemicals can have on the nervous system. The analysis uses fish but, as we discuss here, key neuronal functions are conserved and differences can only be due to differences in metabolism or passage into the brain, factors that can easily be determined. Speed and efficiency of the method, therefore, make it suitable to provide information in risk assessment, as we illustrate here with the effects of bisphenols on adult brain function.

Developmental toxicity of bisphenol S in Caenorhabditis elegans and NODEF mice

The growing concern surrounding bisphenol A (BPA) has led to increased industrial production and application of its analog bisphenol S (BPS). The goals of this study were: (1) To examine the generational effects in the nematode C. elegans for up to three generations following developmental exposure to BPS (0.1, 1.0, 5.0 and 10.0 μM), and (2) To examine the neurotoxicity and metabolic toxicity in NODEF mouse offspring exposed to BPS (3 μg/kg BW) in utero throughout gestation once/day via oral pipette. First, worms were exposed to BPS developmentally for a single period of 48 hours and then propagated for 2 additional generations. Exposure to 0.1 and 1.0 μM BPS decreased lifespan and the number of progeny with an ability to recover in subsequent generations. In contrast, worms exposed to 5.0 or 10.0 μM BPS exhibited a continuous effect in the second generation, e.g., decreased lifespan and reduced number of progeny. Only worms exposed to 10.0 μM BPS continued to have a significant long-term effect (e.g., decreased lifespan) through the third generation. In addition, worms developmentally exposed to BPS at 5.0 μM and 10.0 μM also showed decreases in body bends. In contrast, worms exposed to 0.1 μM BPS exhibited a significant increase in head thrashes. When the multigenerational effects were examined by exposing worms to BPS for 48 hours developmentally at each generation for three generations, an accumulative effect was observed in worms treated with 0.1 or 1.0 μM BPS for two generations, but not for three generations, suggesting a threshold existed. Worms exposed to either 5.0 or 10.0 μM BPS demonstrated accumulative effects through two and three generations. When the developmental effects of BPS were studied in NODEF mice, offspring exposed gestationally exhibited behavioral deficits at 12, but not at 3, weeks of age. Specifically, female offspring had decreases in working and short-term memories while male offspring showed increases in hyperactivity and anxiety-like behaviors. In summary, this study demonstrates the sex-related effects of BPS in NODEF mouse offspring exposed in utero, along with the generational effects observed in C. elegans.

Developmental aspects of the hypothalamic-pituitary network related to reproduction in teleost fish

The hypothalamic-pituitary-gonadal axis is the main system that regulates reproduction in vertebrates through a complex network that involves different neuropeptides, neurotransmitters, and pituitary hormones. Considering that this axis is established early on life, the main goal of the present work is to gather information on its development and the actions of its components during early life stages. This review focuses on fish because their neuroanatomical characteristics make them excellent models to study neuroendocrine systems. The following points are discussed: i) developmental functions of the neuroendocrine components of this network, and ii) developmental disruptions that may impact adult reproduction. The importance of the components of this network and their susceptibility to external/internal signals that can alter their specific early functions and/or even the establishment of the reproductive axis, indicate that more studies are necessary to understand this complex and dynamic network.

Drivers of owning more BPA

Bisphenol A (BPA) is a ubiquitous environmental toxin worldwide. Despite the many studies documenting the toxicity of this substance, it remains a popular choice for consumer products. The internet, magazine articles, and newspaper reports are replete with tips on how to avoid BPA exposure, which mostly spread contradictory and often unscientific information. Therefore, based on a comprehensive search of the available biomedical literature, we summarized several confounding factors that may be directly or indirectly related to human BPA exposure. We found that the unique properties of BPA materials (i.e. low cost, light-weight, resistance to corrosion, and water/air-tightness), lack of personal health and hygiene education, fear of BPA-substitutes (with yet unknown risks), inappropriate production, processing, and marketing of materials containing BPA, as well as the state of regulatory guidance are influencing the increased exposure to BPA. Besides, we detailed the disparities between scientifically derived safe dosages of BPA and those designated as "safe" by government regulatory agencies. Therefore, in addition to providing a current assessment of the states of academic research, government policies, and consumer behaviors, we make several reasonable and actionable recommendations for limiting human exposure to BPA through improved labeling, science-based dosage limits, and public awareness campaigns.

Comparative study on the toxicity and removal of bisphenol S in two typical freshwater algae

Bisphenol S (BPS), one of the most widely used bisphenol A substitutes, has recently received more attention because of its high detection in water and potential toxicity. In the present study, the toxicity and removal of BPS in typical freshwater algae Navicula sp. were investigated under laboratory conditions and the comparative study with Chlorella vulgaris was also explored. BPS was more toxic to Navicula sp. than C. vulgaris with their 120-h EC₅₀ values of 3.89 and 25.19 mg/L, respectively. It may be mainly ascribed to the high tolerance of C. vulgaris to BPS. For instance, the superoxide dismutase (SOD) and catalase (CAT) activities of C. vulgaris were increased under the exposure of 20 mg BPS/L, whereas they were increased in Navicula sp. at 1 mg BPS/L. It is implied that the detoxification mechanism of C. vulgaris was activated until BPS concentration reach to 20 mg L^-1. Moreover, the results had demonstrated that both algae had promoted the removal of BPS at 0.5 mg/L, but the removal could be inhibited as BPS concentration increased. Navicula sp. presented a better removal of BPS because of their higher accumulation, implying that they may be good materials for the removal of BPS. In addition, the sharp increase of BCF value at 72 h in Navicula sp. under the exposure of environmental-related BPS concentration (0.5 mg/L) may indicate a high risk of BPS to aquatic ecosystem. These findings will provide a reference for the risk assessment of BPS in natural waters.

Modulation of folliculogenesis in adult laying chickens by bisphenol A and bisphenol S: Perspectives on ovarian morphology and gene expression

Both bisphenol A (BPA) and its analog bisphenol S (BPS) are industrial chemicals that have been used to make certain plastic products applied in chicken farms, including food and water containers. They are endocrine disrupting chemicals (EDCs) with xenoestrogenic activities and affect reproductive success in many ways. It was hypothesized that BPA and BPS could adversely affect the folliculogenesis in chickens due to their disruption of the estrogen responses, using either genomic or non-genomic mechanisms. This study investigated the deleterious effects of BPA and BPS on the ovaries when adult layer chickens were orally treated with these EDCs at 50 μg/kg body weight, the reference dose for chronic oral exposure of BPA established by the U.S. EPA. The chickens in both BPA and BPS-treated groups showed a decreased number of the preovulatory follicles. BPA-treated chickens showed a significant decrease in the diameter of F1. Additionally, both BPA and BPS treatments increased the infiltrations of lymphocytes and plasma cells in ovaries. Moreover, it was found that the ovaries of BPS-treated chickens weighed the most among the groups. RNA sequencing and subsequent pathway enrichment analysis of differentially expressed genes revealed that both BPA- and BPS-treatment groups showed significant changes in gene expression and pathways related to reproduction, immune function and carcinogenesis. Taken together, both BPA and BPS are potentially carcinogenic and have deleterious effects on the fertility of laying chickens by inducing inflammation, suggesting that BPS may not be a safe replacement for BPA.

Using Estrogenic Activity and Nontargeted Chemical Analysis to Identify Contaminants in Sewage Sludge

Diverse organic compounds, many derived from consumer products, are found in sewage sludge worldwide. Understanding which of these poses the most significant environmental threat following land application can be investigated through a variety of predictive and cell-based toxicological techniques. Nontargeted analysis using high-resolution mass spectrometry with predictive estrogenic activity modeling was performed on sewage sludge samples from 12 wastewater treatment plants in California. Diisobutyl phthalate and dextrorphan were predicted to exhibit estrogenic activity and identified in >75% of sludge samples, signifying their universal presence and persistence. Additionally, the application of an estrogen-responsive cell bioassay revealed reductions in agonistic activity during mesophilic and thermophilic treatment but significant increases in antagonism during thermophilic treatment, which warrants further research. Ten nontarget features were identified (metoprolol, fenofibric acid, erythrohydrobupropion, oleic acid, mestranol, 4'-chlorobiphenyl-2,3-diol, medrysone, scillarenin, sudan I, and N,O-didesmethyltramadol) in treatment set samples and are considered to have influenced the in vitro estrogenic activity observed. The combination of predictive and in vitro estrogenicity with nontargeted analysis has led to confirmation of 12 estrogen-active contaminants in California sewage sludge and has highlighted the importance of evaluating both agonistic and antagonistic responses when evaluating the bioactivity of complex samples.

Toxicity of bisphenol analogues on the reproductive, nervous, and immune systems, and their relationships to gut microbiome and metabolism: insights from a multi-species comparison

Bisphenols are common chemicals found in plastics and epoxy resins. Over the past decades, many studies have shown that bisphenol A (BPA) is a potential endocrine-disrupting chemical that may cause multisystem toxicity. However, the relative safety of BPA analogues is a controversial subject. Herein, we conducted a review of the reproductive toxicity, neurotoxicity, immunotoxicity, metabolic toxicity and gut microbiome toxicity of the BPA analogues in various species, including Caenorhabditis elegans, zebrafish, turtles, sheep, rodents, and humans. In addition, the mechanisms of action were discussed with focus on bisphenol S and bisphenol F. It was found that these BPA analogues exert their toxic effects on different organs and systems through various mechanisms including epigenetic modifications and effects on cell signaling pathways, microbiome, and metabolome in different species. More research is needed to study the relative toxicity of the lesser-known BPA analogues compared to BPA, both systemically and organ specifically, and to better define the underlying mechanisms of action, in particular, the potentials of disrupting microbiome and metabolism.

Biomass-derived chemical substitutes for bisphenol A: recent advancements in catalytic synthesis

Bisphenol A is an oil-derived, large market volume chemical with a wide spectrum of applications in plastics, adhesives and thermal papers. However, bisphenol A is not considered safe due to its endocrine disrupting properties and reproductive toxicity. Several functional substitutes of bisphenol A have been proposed in the literature, produced from plant biomass. Unless otherwise specified, the present review covers the most significant contributions that appeared in the time span January 2015-August 2019, describing the sustainable catalytic synthesis of rigid diols from biomass derivatives. The focus is thereupon on heterogeneous catalysis, use of green solvents and mild conditions, cascade processes in one-pot, and continuous flow setups. More than 500 up-to-date references describe the various substitutes proposed and the catalytic methods for their manufacture, broken down according to the main biomass types from which they originate.

Zebrafish Optomotor Response and Morphology Are Altered by Transient, Developmental Exposure to Bisphenol-A

Estrogen-specific endocrine disrupting compounds (EDCs) are potent modulators of neural and visual development and common environmental contaminants. Using zebrafish, we examined the long-term impact of abnormal estrogenic signaling by testing the effects of acute, early exposure to bisphenol-A (BPA), a weak estrogen agonist, on later visually guided behaviors. Zebrafish aged 24 h postfertilization (hpf), 72 hpf, and 7 days postfertilization (dpf) were exposed to 0.001 μM or 0.1 μM BPA for 24 h, and then allowed to recover for 1 or 2 weeks. Morphology and optomotor responses (OMRs) were assessed after 1 and 2 weeks of recovery for 24 hpf and 72 hpf exposure groups; 7 dpf exposure groups were additionally assessed immediately after exposure. Increased notochord length was seen in 0.001 μM exposed larvae and decreased in 0.1 μM exposed larvae across all age groups. Positive OMR was significantly increased at 1 and 2 weeks post-exposure in larvae exposed to 0.1 μM BPA when they were 72 hpf or 7 dpf, while positive OMR was increased after 2 weeks of recovery in larvae exposed to 0.001 μM BPA at 72 hpf. A time-delayed increase in eye diameter occurred in both BPA treatment groups at 72 hpf exposure; while a transient increase occurred in 7 dpf larvae exposed to 0.1 μM BPA. Overall, short-term developmental exposure to environmentally relevant BPA levels caused concentration- and age-dependent effects on zebrafish visual anatomy and function.

Effect of bisphenol A on craniofacial cartilage development in zebrafish (Danio rerio) embryos: A morphological study

Bisphenol A (BPA), an endocrine-disrupting chemical, is present in everyday-used consumables and common household products. Although the side effects of BPA have been sufficiently explored, little is known the effects of environmentally relevant low levels of BPA on chondrogenesis in skeletal development. Here we used a morphological approach to investigate whether exposure to BPA (0, 0.0038, 0.05, 0.1, 1.0 μM) could affect craniofacial cartilage development of zebrafish embryo. Furthermore, we sought to determine receptor-mediated BPA induced chondrogenesis toxicity by co-exposing developing embryos to BPA and various inhibitors. Low-dose BPA affected heart rate and induced body and head elongation of larvae. Quantitative morphometric and histopathological analysis revealed that BPA exposure changed the angle and length of craniofacial cartilage elements and disrupted chondrocytes. BPA induced pharyngeal cartilage defects via multiple cellular pathways, including estrogen receptor, androgen receptor, and estrogen-related receptors. Our findings demonstrate that BPA alters the normal development of cartilage and craniofacial structures in zebrafish embryos. Furthermore, in this study we find multiple cellular pathways mediating the effects of BPA-induced craniofacial chondrogenesis toxicity. Further experiments will allow for establishing a connection between BPA and increased risk of congenital malformation of the facial cranium in BPA-exposed populations.