Bisphenol A causes hyperactivity in the rat concomitantly with impairment of tyrosine hydroxylase immunoreactivity

DNA methylation profiles of transgenerational rat hyperactivity primed by silver nanoparticles: comparison with valproate model rats of autism

There is an increasing body of evidence suggesting that a single exposure to certain chemicals can have transgenerational effects, with the underlying mechanism believed to be epigenetic. However, it remains largely unknown whether psychiatric conditions like ADHD or autism, induced by environmental chemicals, can be inherited across generations. Pregnant rats were purchased from a commercial breeder. On the 7th day of gestation (E7), they were divided into two groups: one group was orally exposed to silver nanoparticles (AgNP; 4mg/kg), while the control group received vehicle alone. The subsequent generation (F1) underwent spontaneous motor activity (SMA) measurements at 8~11 weeks of age. For breeding at 26 weeks of age, rats with higher SMA were selected from hyperactive litters, while untreated rats were randomly selected. This process was continued for four generations in both groups. The AgNP-primed rats at 4th generation displayed significantly higher SMA, 1.8 times greater than that of untreated rats. Intraperitoneal injection of valproic acid (150mg/kg), an epigenetic modifier to 5-day-old rats causes adult hyperactivity (1.4-fold), suggesting that epigenetic modification contributes to rat hyperactivity. Global DNA methylation profiles in the mesencephalon were positively correlated in both groups of hyperactive rats. Furthermore, there were 7 to 8 common genes showing both hypermethylation and hypomethylation, which are involved in neuronal development, neuronal function, transcriptional activity, DNA binding activity, cell differentiation, ubiquitination processes, or histone modification, including Pax 6 and Mecp 2. Thus, it is most likely that rats retain hyperactivity through mesencephalic DNA methylation status across transgeneration.

Determination of the occurrence of and exposure to bisphenol A and its analogues in carbonated beverages and canned tuna using liquid chromatography - tandem mass spectrometry

Bisphenol A (BPA), a known endocrine disruptor, is commonly used in food containers and packaging. Recently, alternatives such as bisphenol AF (BPAF), bisphenol B (BPB), and bisphenol E (BPE) have been introduced to replace BPA. However, these substitutes have been reported to exhibit toxicity levels similar to BPA. In this study, we developed and validated a method for the analysis of trace bisphenols (BPA, BPAF, BPB, and BPE) in food using immunoaffinity column (IAC) clean-up. The method demonstrated satisfactory accuracy and precision. We applied this validated method to analyze 56 carbonated beverage samples and 30 canned tuna samples. In the carbonated beverages, average concentrations of BPA and BPAF were 0.4 and 0.2 μg kg-1, respectively. In canned tuna, BPA and BPAF were found at average concentrations of 22.2 and 0.7 μg kg-1, respectively, while BPB and BPE were not detected in any samples. Estimated exposure levels ranged from 0.13 to 0.18 ng kg bw-1 day-1 in the general population and from 205.2 to 232.0 ng kg bw-1 day-1 among consumers. The commercial IAC-based analytical method used in this study can contribute to the safety management of BPA, BPAF, BPB, and BPE.

Mechanistic Insights into Bisphenol A-Mediated Male Infertility: Potential Role of Panax Ginseng Extract

Male infertility is identified by the inability of a man to successfully impregnate his fertile female partner, even following a year of regular unprotected sexual intercourse. About half of all infertility cases are attributed to what is known as "male factor" infertility. The escalating prevalence of male infertility in the contemporary era across the globe can be largely attributed to environmental pollution, which is the common etiological factor due to the ubiquitous presence of the environmental contaminants. Bisphenol A is recognized as an endocrine-disrupting chemical that has adverse effects on both male and female reproductive systems. On the other hand, numerous studies have demonstrated that Panax ginseng possessed the potential to improve male infertility parameters; promote spermatogenesis, recover the quality and motility of sperm and enhance testicular functions as it acted as a natural androgen supplement. The objective of this review is to offer a summary of the findings obtained from the current research data on the insult of bisphenol A (BPA) on male infertility and its supposed mode of action, as well as shed light on the potent ameliorative role of Panax ginseng extract, with a special focus on the mechanism behind its action. This review delivers a clear understanding of BPA mechanism of action on male infertility and the presumed risks deriving from its exposure. Also, this review provides evidence for the functional role of Panax ginseng extract in restoring male fertility.

Adolescent endocrine disrupting chemical exposure and academic achievement

BACKGROUND

Epidemiologic studies support associations of exposure to endocrine disrupting chemicals (EDCs), such as some phthalates, phenols, and parabens with a wide range of cognitive and behavioral traits. While many of these traits are associated with academic achievement, the relationship of EDC exposure specifically with academic achievement in adolescence has not yet been studied.

OBJECTIVE

We assessed the association of urinary biomarker concentrations of EDCs with academic achievement in adolescents as well as the potential for psychosocial factors to modify associations.

METHODS

We quantified urinary concentrations of select EDCs in 205 adolescent participants from the New Bedford Cohort (NBC), a prospective birth cohort of children born to mothers residing near the New Bedford Harbor Superfund site in Massachusetts, and estimated associations between EDCs and adolescent academic achievement assessed with the Wide Range Achievement Test (WRAT). Measures of socioeconomic status and the home environment were used to estimate psychosocial stress.

RESULTS

Urinary concentrations of antiandrogenic phthalates were inversely associated with Math Computation scores. For example, each doubling of the concentration of antiandrogenic phthalate metabolites in urine was associated with a 1.94 point decrease (95% CI: 3.84, -0.05) in Math Computation scores, indicating poorer performance. For the most part, associations were stronger in adolescents with more, as compared to less, social disadvantage, but most of these differences did not achieve statistical significance.

CONCLUSION

Our findings support the potential for adolescents' exposure to antiandrogenic phthalates to correlate with poorer academic achievement in math, particularly among participants with greater psychosocial stress.

The passive avoidance task ameliorate the toxic effects of bisphenol A on dopamine D1 receptor density in hippocampus, amygdala, and cerebellum of male rats

INTRODUCTION

Dopamine D1 receptor seems to play a role in mediating plasticity. Therefore, the present study aimed to investigate the effects of passive avoidance tasks postexposed to BPA on dopamine D1 receptor density in the hippocampus, amygdala, and cerebellum of male rats.

METHODS

Thirty-five male Sprague-Dawley rats weighing 220.300 g, in standard light-dark 12 h light/12 h dark were used in the present study; water and food were ad libitum. Animals were divided into six groups. Administration of BPA 5 and 50 mg/kg/day were gavaged for 15 days. Learning and memory assessment were done by a shuttle box after 15 days of BPA administration. The density of the dopamine D1 receptor was investigated using an immunohistochemistry (IH) procedure. For determining the color difference in IH sections, Image Analyzer software was used. The data were analyzed by one-way ANOVA followed by Tukey's as a post hoc test.

RESULTS

The data showed that BPA in both doses could significantly increase the density of dopamine D1 receptors in the hippocampus, amygdala, and cerebellum of male rats; learning in rats postexposed to BPA improves dopamine D1 receptor density significantly in three brain structures.

DISCUSSION

According to the results, passive avoidance learning and memory can improve the density of dopamine D1 receptors in the hippocampus, amygdala, and cerebellum of male rats.

Chemical nature of attention deficit hyperactivity disorder (ADHD) - related chemical subfamily

Endocrine disruptors have been subjected to health risk assessments. Bioassays and chemoinformatics are very useful tools to characterize their chemical nature. By performing rat hyperactivity assays, we screened some endocrine disruptors, resulting in the classification of two groups: hyperactivity-associated and hyperactivity-negative chemicals. Moreover, many epidemiological studies have reported the correlation between most of the hyperactivity-associated chemicals identified in our bioassay and patients with attention deficit hyperactivity disorder (ADHD); thus, these chemicals are emerging as a subfamily of hyperactivity-associated chemicals among endocrine disruptors. Using RDKit, chemoinformatic analyses revealed no significant differences in the distribution of molecular weight between the two groups, but significant differences in "Fraction CSP3" (number of sp³-hybridized carbons/total carbon count) and the Tanimoto coefficient were observed. Additionally, hyperactivity-associated chemicals were distinguished from two known classes of dopaminergic toxins by the Tanimoto coefficient. Machine learning methods were also applied for classification, regression analyses, and prediction. A neural network model classified the two groups. Random forest methods also showed good prediction (R = 0.9, MAE (mean absolute error) = 0.06). Using a junction tree variational autoencoder, the core structure was interpolated between phthalate and phenol in the hyperactivity-associated group. Thus, I describe the chemical nature of a new chemical family that might promote the development of ADHD in humans.

Effects of Maternal Exposure to Decamethylcyclopentasiloxane on the Alternations in Offspring Behaviors in Mice

D5, a member of the cyclic siloxane family, is widely used in personal care products such as shampoo, cosmetics, and deodorant and as an industrial intermediate. D5 can mainly be absorbed orally or through inhalation. Through these routes, people are exposed to D5 daily. However, the risk of prenatal exposure to D5 has not been fully elucidated. In this study, the effect of D5 on neural development was established through behavioral tests on offspring mice. The result confirmed that the maternal administration of 12 mg/kg of D5 showed depression in tail suspension and decreased performance in the forced swimming test as well as an increase in repetitive activity in both the marble-burying test and grooming test compared to the vehicle group. Furthermore, the 12 mg/kg group showed a decrease in cognitive ability and social behavior in the three-chamber test. In the novel object recognition test, memory impairment and a lack of exploring ability were found in the 12 mg/kg group. In conclusion, it is suggested that maternal D5 exposure has developmental neurotoxicity and can cause behavioral disorders in the offspring of mice. Thus, the usage of D5 needs to be considered carefully.

Sex-specific Effects of Endocrine-disrupting Chemicals on Brain Monoamines and Cognitive Behavior

The period of brain sexual differentiation is characterized by the development of hormone-sensitive neural circuits that govern the subsequent presentation of sexually dimorphic behavior in adulthood. Perturbations of hormones by endocrine-disrupting chemicals (EDCs) during this developmental period interfere with an organism's endocrine function and can disrupt the normative organization of male- or female-typical neural circuitry. This is well characterized for reproductive and social behaviors and their underlying circuitry in the hypothalamus and other limbic regions of the brain; however, cognitive behaviors are also sexually dimorphic, with their underlying neural circuitry potentially vulnerable to EDC exposure during critical periods of brain development. This review provides recent evidence for sex-specific changes to the brain's monoaminergic systems (dopamine, serotonin, norepinephrine) after developmental EDC exposure and relates these outcomes to sex differences in cognition such as affective, attentional, and learning/memory behaviors.

Are BPA Substitutes as Obesogenic as BPA?

Metabolic diseases, such as obesity, Type II diabetes and hepatic steatosis, are a significant public health concern affecting more than half a billion people worldwide. The prevalence of these diseases is constantly increasing in developed countries, affecting all age groups. The pathogenesis of metabolic diseases is complex and multifactorial. Inducer factors can either be genetic or linked to a sedentary lifestyle and/or consumption of high-fat and sugar diets. In 2002, a new concept of “environmental obesogens” emerged, suggesting that environmental chemicals could play an active role in the etiology of obesity. Bisphenol A (BPA), a xenoestrogen widely used in the plastic food packaging industry has been shown to affect many physiological functions and has been linked to reproductive, endocrine and metabolic disorders and cancer. Therefore, the widespread use of BPA during the last 30 years could have contributed to the increased incidence of metabolic diseases. BPA was banned in baby bottles in Canada in 2008 and in all food-oriented packaging in France from 1 January 2015. Since the BPA ban, substitutes with a similar structure and properties have been used by industrials even though their toxic potential is unknown. Bisphenol S has mainly replaced BPA in consumer products as reflected by the almost ubiquitous human exposure to this contaminant. This review focuses on the metabolic effects and targets of BPA and recent data, which suggest comparable effects of the structural analogs used as substitutes.

Dose-response metabolomics and pathway sensitivity to map molecular cartography of bisphenol A exposure

In the toxicological regime, the toxicological endpoint and its dose-response relationship are two of the most prominent characters in conducting a risk assessment for chemical exposure. Systems biological methods have been used to comprehensively characterize the impact of toxicants on the biochemical pathways. However, the majority of the current studies are only based on single-dose, and limited information can be extrapolated to other doses from these experiments, regardless of the sensitivity of each endpoint. This study aims to understand the dose-response metabolite dysregulation pattern and metabolite sensitivity at the system-biological level. Here, we applied bisphenol A (BPA), an endocrine-disrupting chemical (EDC), as the model chemical. We first employed the global metabolomics method to characterize the metabolome of breast cancer cells (MCF-7) upon exposure to different doses (0, 20, 50, and 100 µM) of BPA. The dysregulated features with a clear dose-response relationship were also effectively picked up with an R-package named TOXcms. Overall, most metabolites were dysregulated by showing a significant dose-dependent behaviour. The results suggested that BPA exposure greatly perturbed purine metabolism and pyrimidine metabolism. Interestingly, most metabolites within the purine metabolism were described as a biphasic dose-response relationship. With the established dose-response relationship, we were able to fully map the metabolite cartography of BPA exposure within a wide range of concentrations and observe some unique patterns. Furthermore, an effective concentration of certain fold changes (e.g., EC₊₁₀ means the dose at which metabolite is 10% upregulated) and metabolite sensitivity were defined and introduced to this dose-response omics information. The result showed that the purine metabolism pathway is the most venerable target of BPA, which can be a potential endogenous biomarker for its exposure. Overall, this study applied the dose-response metabolomics method to fully understand the biochemical pathway disruption of BPA treatment at different doses. Both dose-response omics strategy and metabolite sensitivity analysis can be further considered and emphasized in future chemical risk assessments.

Dietary exposure to bisphenol A affects memory function and neuroimmune biomarkers in allergic asthmatic mice

Bisphenol A (BPA) is a raw material of polycarbonate and epoxy resin. It is used for various household electrical appliances, electronic equipment, office automation equipment, medical equipment, mobile phones, paints for automobiles, internal surface coating of cans, and adhesives for civil engineering and construction. BPA is a well-known endocrine-disrupting chemical, and it was reported that BPA has an adverse effect on the nervous and immune systems. However, BPA-induced memory impairment and changes in neuroimmune biomarkers in the allergic asthmatic subject are not known yet. We aim to investigate the dietary exposure effect of BPA on brain function and biomarkers using allergic an asthmatic mouse model. Five-week-old male C3H/HeJSlc mice were fed two doses of BPA [0.901, 9.01 μg/kg/day] contained chow diet from 5 to 11 weeks old and ovalbumin (OVA) was given by intratracheal instillation every 2 weeks. Memory function was determined by a novel object recognition test. Genes related to memory and immune markers in the hippocampus were investigated with the real-time polymerase chain reaction (RT-PCR) method. In this study, impaired novel object recognition occurred in BPA-exposed mice in the presence of an allergen. Moreover, upregulation of expression level of neuroimmune biomarkers such as N-methyl-D-aspartate receptor, tumor necrosis factor-α, ionized calcium-binding adapter molecule-1, cyclooxygenase-2, and heme oxygenase-1 in the hippocampus was observed in BPA-exposed allergic asthmatic mice. These findings show that BPA exposure can induce neuroinflammation and which triggers impairment of memory function in mice with allergic asthma. Our study indicated that dietary exposure to BPA may affect higher brain functions by modulating neuroimmune biomarkers in allergic asthmatic subjects.

Detrimental Effects of Bisphenol Compounds on Physiology and Reproduction in Fish: A Literature Review

Bisphenol-A is one of the most studied endocrine-chemicals, which is widely used all over the world in plastic manufacture. Because of its extensive use, it has become one of the most abundant chemical environmental pollutants, especially in aquatic environments. BPA is known to affect fish reproduction via estrogen receptors but many studies advocate that BPA affects almost all aspects of fish physiology. The possible modes of action include genomic, as well as and non-genomic mechanisms, estrogen, androgen, and thyroid receptor-mediated effects. Due to the high detrimental effects of BPA, various analogs of BPA are being used as alternatives. Recent evidence suggests that the analogs of BPA have similar modes of action, with accompanying effects on fish physiology and reproduction. In this review, a detailed comparison of effects produced by BPA and analogs and their mode of action is discussed.

Association of Exposure to Endocrine-Disrupting Chemicals During Adolescence With Attention-Deficit/Hyperactivity Disorder-Related Behaviors

IMPORTANCE

Attention-deficit/hyperactivity disorder (ADHD) is the most common childhood neurobehavioral disorder. Studies suggest that prenatal and early childhood exposure to endocrine-disrupting chemicals may be associated with ADHD, but the association during adolescence has not been studied to date.

OBJECTIVE

To evaluate the association between exposure to select endocrine-disrupting chemicals during adolescence and ADHD-related behaviors.

DESIGN, SETTING, AND PARTICIPANTS

For this cross-sectional analysis, data were collected from 205 adolescents in the New Bedford Cohort, an ongoing prospective birth cohort, between June 18, 2011, and June 10, 2014. The adolescents provided spot urine samples and underwent neurodevelopmental testing. Statistical analyses performed from January 15 to December 31, 2019, used a repeated-measures analysis with multivariate modified Poisson models to estimate the adjusted relative risk of ADHD-related behaviors associated with exposure to endocrine-disrupting chemicals.

EXPOSURES

Urinary biomarker concentrations of endocrine-disrupting chemicals or their metabolites, including phthalates, parabens, phenols, and triclocarban, were quantified. Summary exposure measures were created, combining biomarker concentrations of chemicals with a shared mechanism of action, exposure pathway, or chemical class.

MAIN OUTCOMES AND MEASURES

Behaviors related to ADHD were assessed with up to 14 indices from self-, parent-, and teacher-completed behavioral checklists using validated and standardized instruments; specifically, the Conners Attention Deficit Scale and the Behavior Assessment System for Children, Second Edition. Scores on each index were dichotomized to identify those with evidence of a significant behavioral problem, defined by each scale's interpretive guidelines.

RESULTS

Among the 205 participants, the mean (SD) age at assessment was 15.3 (0.7) years, with 112 girls (55%) and 124 non-Hispanic White participants (61%). The median urine concentrations were 0.45 μmol/L of Σantiandrogenic phthalates, 0.13 μmol/L of ΣDEHP metabolites, 0.49 μmol/L of Σpersonal care product phthalates, 0.35 μmol/L of Σparabens, 0.02 μmol/L of Σbisphenols, and 0.02 μmol/L of Σdichlorophenols. A total of 82 (40%) had scores consistent with a significant behavioral problem, whereas 39 (19%) had an ADHD diagnosis. Each 2-fold increase in the sum of antiandrogenic phthalate concentrations was associated with a 1.34 (95% CI, 1.00-1.79) increase in the risk of significant ADHD-related behavior problems, whereas a 2-fold increase in the sum of dichlorophenols was associated with a 1.15 (95% CI, 1.01-1.32) increased risk. These associations tended to be stronger in male participants, but comparisons of sex-specific differences were imprecise.

CONCLUSIONS AND RELEVANCE

Endocrine-disrupting chemicals are used in a wide variety of consumer products resulting in ubiquitous exposure. The study findings suggest that exposure to some of these chemicals, particularly certain phthalates, during adolescence may be associated with behaviors characteristic of ADHD.

A potential role for dendritic spines in bisphenol-A induced memory impairments during adolescence and adulthood

Developmental exposure to Bisphenol A (BPA), an endocrine disrupting chemical, alters many behaviors and neural parameters in rodents and non-human-primates. The effects of BPA are mediated via gonadal hormone, primarily, estrogen receptors, and are not limited to the perinatal period since recent studies show impairments further into development. The studies described in this chapter address the effects of BPA administration during early adolescence on memory and dendritic spine density in intact male and female rats as well as ovariectomized (OVX) rats in late adolescence and show that some of these adolescent induced changes endure into adulthood. In general, BPA impairs spatial memory and induces decreases in dendritic spine density in the hippocampus and the medial prefrontal cortex, two areas important for memory. The effects of adolescent BPA in intact females are compared to OVX females in an attempt to address the importance of estrogens in the mechanism(s) underlying the profound neuronal alterations occurring during adolescent development. In addition, potential mechanisms by which acute and chronic BPA induce structural alterations are discussed. These studies suggest a complex interaction between low doses of BPA, gonadal state and neural development.

Perinatal exposure to bisphenol A at the intersection of stress, anxiety, and depression

Endocrine-disrupting compounds (EDCs) are common contaminants in our environment that interfere with typical endocrine function. EDCs can act on steroid and nuclear receptors or alter hormone production. One particular EDC of critical concern is bisphenol A (BPA) due to its potential harm during the perinatal period of development. Previous studies suggest that perinatal exposure to BPA alters several neurotransmitter systems and disrupts behaviors associated with depression and anxiety in the rodent offspring later in life. Thus, dysregulation in neurotransmission may translate to behavioral phenotypes observed in mood and arousal. Many of the systems disrupted by BPA also overlap with the stress system, although little evidence exists on the effects of perinatal BPA exposure in relation to stress and behavior. The purpose of this review is to explore studies involved in perinatal BPA exposure and the stress response at neurochemical and behavioral endpoints. Although more research is needed, we suggest that perinatal BPA exposure is likely inducing variations in behavioral phenotypes that modulate their action through dysregulation of neurotransmitter systems sensitive to stress and endocrine disruption.

The Case for BPA as an Obesogen: Contributors to the Controversy

Since the inception of the term endocrine disruptor, the idea that the environment is an important determinant of phenotype has motivated researchers to explore the effect of low dose exposure to BPA during organogenesis. The syndrome observed was complex, affecting various endpoints such as reproduction and reproductive tissues, behavior, mammary gland development and carcinogenesis, glucose homeostasis, and obesity. This constellation of impacted endpoints suggests the possibility of complex interactions among the multiple effects of early BPA exposure. One key finding of our rodent studies was alterations of energy and amino-acid metabolism that were detected soon after birth and continued to be present at all time points examined through 6 months of age. The classical manifestations of obesity and associated elements of metabolic disease took a longer time to become apparent. Here we examine the validity of the often-mentioned lack of reproducibility of obesogenic effects of BPA, starting from the known environmental causes of variation, which are diverse and range from the theoretical like the individuation process and the non-monotonicity of the dose-response curve, to the very pragmatic like housing, feed, and time and route of exposure. We then explore environmental conditions that may hinder reproducibility and discuss the effect of confounding factors such as BPA-induced hyperactivity. In spite of all the potential sources of variation, we find that some obesogenic or metabolic effects of BPA are reproducibly observed when study conditions are analogous. We recommend that study authors describe details of their study conditions including the environment, husbandry, and feed. Finally, we show that when experimental conditions are strictly maintained, reproducibility, and stability of the obese phenotype is consistently observed.

Occurrence, endocrine-related bioeffects and fate of bisphenol A chemical degradation intermediates and impurities: A review

In recent decades, increasing attention has been directed toward the effects of bisphenol A (BPA) as an environmental pollutant, primarily due to its demonstrated endocrine-disruptive effects. A growing body of evidence indicates that many BPA derivatives also exhibit endocrine activity and other adverse biological properties. A review of the published literature was performed to identify BPA degradation intermediates resulting from chemical degradation processes of BPA, as well as BPA's associated co-pollutants. Products of biological metabolism were not included in this study. Seventy-nine chemicals were identified. Of these chemicals, a subset - those containing two 6-membered aromatic rings connected by a central ring-linking carbon - was identified, and a further literature review was conducted to identify demonstrated biological effects associated with the chemicals in this subset. The objectives of this review were to assess the potential risks to human and environmental health associated with BPA derivatives, characterize our current understanding of BPA's degradation intermediates and co-pollutants, and aid in the identification of compounds of interest that have received insufficient scrutiny.

Prenatal exposure to bisphenol A and hyperactivity in children: a systematic review and meta-analysis

BACKGROUND

Attention-deficit hyperactivity disorder (ADHD) has increased in prevalence in the past decade. Studies attempting to identify a specific genetic component have not been able to account for much of the heritability of ADHD, indicating there may be gene-environment interactions underlying the disorder, including early exposure to environmental chemicals. Based on several relevant studies, we chose to examine bisphenol A (BPA) as a possible contributor to ADHD in humans. BPA is a widespread environmental chemical that has been shown to disrupt neurodevelopment in rodents and humans.

OBJECTIVES

Using the Office of Health Assessment and Translation (OHAT) framework, a systematic review and meta-analysis was designed to determine the relationship between early life exposure to BPA and hyperactivity, a key diagnostic criterion of ADHD.

DATA SOURCES

Searches of PubMed, Web of Science, and Toxline were completed for all literature to January 1, 2017.

STUDY ELIGIBILITY CRITERIA

For inclusion, the studies had to publish original data, be in the English language, include a measure of BPA exposure, and assess if BPA exposure affected hyperactive behaviors in mice, rats or humans. Exposure to BPA had to occur at <3 months of age for humans, up to postnatal day 35 for rats and up to postnatal day 40 for mice. Exposure could occur either gestationally (via maternal exposure) or directly to the offspring.

STUDY APPRAISAL AND SYNTHESIS METHODS

Studies were evaluated using the OHAT risk of bias tool. The effects in humans were assessed qualitatively. For rodents exposed to 20 μg/kg/day BPA, we evaluated the study findings in a random effects meta-analytical model.

RESULTS

A review of the literature identified 29 rodent and 3 human studies. A random effects meta-analysis showed significantly increased hyperactivity in male rodents. In humans, early BPA exposure was associated with hyperactivity in boys and girls.

LIMITATIONS, CONCLUSIONS, AND IMPLICATIONS OF KEY FINDINGS

We concluded that early life BPA exposure is a presumed human hazard for the development of hyperactivity. Possible limitations of this systematic review include deficiencies in author reporting, exclusion of some literature based on language, and insufficient similarity between human studies. SRs that result in hazard-based conclusions are the first step in assessing and mitigating risks. Given the widespread exposure of BPA and increasing diagnoses of ADHD, we recommend immediate actions to complete such risk analyses and take next steps for the protection of human health. In the meantime, precautionary measures should be taken to reduce exposure in pregnant women, infants and children. The present analysis also discusses potential mechanisms by which BPA affects hyperactivity, and the most effective avenues for future research.

SYSTEMATIC REVIEW REGISTRATION NUMBER

Not available.

Suppressive effects of neonatal bisphenol A on the neuroendocrine system

The aim of this study was to assess the effects of neonatal bisphenol A (BPA) administration on neuroendocrine features (the thyroid–brain axis). BPA (20 or 40 µg/kg) was orally administered to juvenile male albino rats ( Rattus norvegicus) from postnatal days (PNDs) 15 to 30. Both doses resulted in lower serum thyroxine (T4), triiodothyronine (T3), and growth hormone levels and higher thyrotropin level than the control levels at PND 30. In the neonatal cerebellum and cerebrum, vacuolation, pyknosis, edema, degenerative changes, and reductions in the size and number of the cells were observed in both treated groups. Alternatively, elevations in oxidative markers (lipid peroxidation, nitric oxide, and hydrogen peroxide [H2O2]) at both dose levels were recorded at PND 30, along with decreased activities of antioxidant markers (ascorbic acid, total thiol [t-SH], glutathione, glutathione peroxidase, glutathione reductase, glutathione-S-transferase, and catalase) with respect to control levels. Thus, the BPA-induced hypothyroid state may disturb the neonatal thyroid–brain axis via production of free radicals, and this could damage the plasma membrane and cellular components, delaying cerebrum and cerebellum development.

Formula Feeding as a Risk Factor for Attention-Deficit/Hyperactivity Disorder: Is Bisphenol A Exposure a Smoking Gun?

OBJECTIVE

Breastfeeding during infancy is associated with a lower risk of attention-deficit/hyperactivity disorder (ADHD). Although this is presumably due to breast milk's nutritional advantages, formula-fed infants have, until recently, also been exposed to bisphenol A (BPA), a neurotoxic chemical previously used to manufacture baby bottles and formula cans. Our goal was to examine the association between formula feeding and preschool ADHD in 2 comparable, serial cohorts of preschool children who differ in BPA exposure during infancy.

METHODS

Cross-sectional analysis of the 2007 and 2011/12 National Survey of Children's Health (NSCH). Logistic regression was used to model preschool ADHD diagnoses as a function of breastfeeding, adjusting for 12 possible confounding variables using a propensity score.

RESULTS

In the 2007 data set (weighted n = 9,644,405), formula-fed subjects had a 5-fold increased odds of ADHD compared with breastfed subjects (adjusted odds ratio [aOR]: 5.58, 95% confidence interval [CI], 2.16-14.41). In the 2011/12 data set (n = 9,732,865), there was no significant association between formula feeding and later ADHD (aOR: 1.05, 95% CI, 0.42-2.64). This is despite an increase in the prevalence of preschool ADHD in 2011 (0.88%) compared with 2007 (0.40%) (Rao-Scott χ, p < .0075).

CONCLUSION

Compared with breastfed infants, ADHD was more common among formula-fed infants in the 2007 but not the 2011/12 sample, where exposure to BPA was markedly reduced. These findings suggest that the reduced prevalence of ADHD among breastfed infants may not be due to the nutritional benefits of breast milk, but rather early exposure to BPA, a neurotoxic chemical previously found in infant formula.

Bisphenol A inhibits compound action potentials in the frog sciatic nerve in a manner independent of estrogen receptors

Although the endocrine disruptor bisphenol A (BPA) is reported to inhibit nerve conduction, the underlying mechanisms are unclear. Therefore, in the present study, we examined the effect of BPA on compound action potentials (CAPs) recorded from the frog sciatic nerve using the air-gap method. Treatment of the sciatic nerve with BPA (0.5 mM) for 20 min reduced the peak amplitude of the CAP by approximately 60% in a partially reversible manner. The reduction in the CAP peak amplitude was concentration-dependent, with a half-maximal inhibitory concentration (IC₅₀) value of 0.31 mM. This effect of BPA was unaffected by an estrogen-receptor antagonist, 4-hydroxytamoxifen, which by itself reduced CAP peak amplitude, with an IC₅₀ value of 0.26 mM (comparable to that of BPA). The natural estrogen 17β-estradiol, at the highest dissolvable concentration (0.05 mM), had an effect similar to that of BPA. The IC₅₀ value of BPA was comparable to those of some local anesthetics in inhibiting frog CAPs. Our findings suggest that BPA inhibits nerve conduction in a manner independent of estrogen receptors. This action of BPA may underlie, at least in part, the neurotoxicity of the compound.

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Bisphenol A acutely inhibits compound action potentials in nerve fibers.

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The effect of bisphenol A is not mediated by estrogen receptors.

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The effect of bisphenol A is comparable to those of local anesthetics.

Neuropeptide Y expression confers benzo[a]pyrene induced anxiolytic like behavioral response during early adolescence period of male Wistar rats

Environmental neurotoxicant like benzo[a]pyrene (B[a]P) is known to induce neurobehavioral changes. Our previous reports address the adverse effect of B[a]P on the neurobehavioral responses and neuromorphology of sensitive brain regions in adolescent rats. Present study was conducted on male Wistar rat neonates at postnatal day 5 (PND5) to ascertain B[a]P induced anxiolytic like behavioral response could be an outcome of neuropeptide Y (NPY) overexpression in brain. Single intracisternal administration of B[a]P was carried out at PND5 to elucidate the role of NPY on neurobehavioral responses at PND30. The behavioral studies showed anxiolytic like effect of B[a]P in both light and dark box and elevated plus maze tests. Antioxidant assay involving glutathione peroxidase activity was significantly decreased where as lipid peroxidation was significantly augmented in both hippocampus and hypothalamus of B[a]P treated group as compared to naive and control. The neurotransmitter estimation by HPLC-ECD showed significant increase in 5-HT level in both hippocampus and hypothalamus of B[a]P treated group. Significant elevation in NPY expression was observed in both hippocampus and hypothalamus of B[a]P group. Intracellular Ca²⁺ estimation using Fura-2AM by fluorometry showed that B[a]P induced increase in Ca²⁺ influx was associated with augmented NPY expression in brain. As NPY has orexigenic effect, our result revealed that there was a significant increase in body weight at PND30 following B[a]P administration to rat neonates at PND5. These findings suggested that NPY overexpression in brain regions might be associated with anxiolytic like behavioral response and orexigenic effect in rats following single intracisternal B[a]P administration. Future research directing towards understanding the signaling cascades of B[a]P induced biochemical and neuromorphological alteration might address the independent pathway which induce neurodegeneration despite NPY overexpression in brain regions of adolescent rats.

Neonatal rotenone lesions cause onset of hyperactivity during juvenile and adulthood in the rat

Attention deficit hyperactivity disorder (ADHD) is characterized by behavioral and cognitive symptoms. Longitudinal studies demonstrated that the symptoms remains clinically significant for the majority of ADHD children into adulthood. Furthermore, a population-based birth cohort provided the initial evidence of adult ADHD that lacks a history of childhood ADHD. We previously demonstrated that neonatal exposure to bisphenol A, an environmental chemical caused hyperactivity in the juvenile. Here, we extend to examine other chemical such as rotenone, a dopaminergic toxins. Oral administration of rotenone (3mg/kg) into 5-day-old male Wistar rats significantly caused hyperactivity at adulthood (8∼11 weeks old; p<0.05). It was about 1.3∼1.4-fold more active in the nocturnal phase after administration of rotenone than control rats. Higher dose (16mg/kg) or repeated lower dose of rotenone (1mg/kg/day for 4days) caused hyperactivity in the juvenile. Furthermore, DNA array analyses showed that neonatal exposure to rotenone altered the levels of gene expression of several molecules related to apoptosis/cell cycle, ATPase, skeletal molecule, and glioma. Bivariate normal distribution analysis indicates no correlation in gene expression between a hyperactivity disorder model and a Parkinson's disease model by rotenone. Thus, we demonstrate a rotenone models of ADHD whose onset varies during juvenile and adulthood.

Bisphenol A exposure and symptoms of anxiety and depression among inner city children at 10-12 years of age

BACKGROUND

Experimental and epidemiological studies suggest that gestational exposure to Bisphenol A (BPA), an ubiquitous endocrine disrupting chemical, may lead to neurobehavioral problems in childhood; however, not all results have been consistent. We previously reported a positive association between prenatal BPA exposure and symptoms of anxiety/depression reported by the mother at child age 7-9 years in boys, but not girls.

OBJECTIVES

Here, in the same birth cohort, we investigated the association of prenatal BPA exposure with symptoms of depression and anxiety self-reported by the 10-12 year olds, hypothesizing that we would observe sex-specific differences in anxiety and depressive symptoms.

METHODS

African-American and Dominican women living in Northern Manhattan and their children were followed from mother's pregnancy through children's age 10-12 years. BPA was quantified in maternal urine collected during the third trimester of pregnancy and in child urine collected at ages 3 and 5 years. Children were evaluated using the Revised Children's Manifest Anxiety Scale (RCMAS) and Children's Depression Rating Scale (CDRS). We compared the children in the highest tertile of BPA concentration to those in the lower two tertiles. Associations between behavior and prenatal (maternal) BPA concentration or postnatal (child) BPA concentration were assessed in regression models stratified by sex.

RESULTS

Significant positive associations between prenatal BPA and symptoms of depression and anxiety were observed among boys. Postnatal BPA exposure was not significantly associated with outcomes. There was substantial co-occurrence of anxiety and depressive symptoms in this sample.

CONCLUSION

These results provide evidence that prenatal BPA exposure is associated with more symptoms of anxiety and depression in boys but not in girls at age 10-12 years.

Association of Bisphenol A exposure and Attention-Deficit/Hyperactivity Disorder in a national sample of U.S. children

BACKGROUND

Bisphenol A (BPA) has been linked to changes in the dopamine system and development of an Attention-Deficit/Hyperactivity Disorder (ADHD) phenotype in animal models, with differing effects in males compared to females. We examined the association between urinary BPA concentrations and ADHD in a national sample of U.S. children, and whether this association differs by child sex.

METHODS

We used data from the 2003-2004 National Health and Nutrition Examination Survey, a cross-sectional, nationally representative sample of the U.S.

POPULATION

Participants were 8-15 years of age (N=460). Using a diagnostic interview to ascertain the presence of ADHD in the past year, multivariable logistic regression examined the link between concurrent urinary BPA concentrations and ADHD status.

RESULTS

Of the 460 participants, 7.1% [95% CI: 4.4-11.3] met Diagnostic and Statistical Manual of Mental Disorders - Fourth Edition (DSM-IV) criteria for ADHD. Children who had BPA concentrations at or above the median of the sample had higher prevalence of meeting criteria for ADHD (11.2% [95% CI: 6.8-17.8]) than those with BPA concentrations below the median (2.9% [95% CI: 1.1-7.2]). Higher urinary BPA concentrations were associated with ADHD (adjusted odds ratio [aOR]: 5.68 [95% CI: 1.6-19.8] for BPA concentrations above vs. below the median). In sex-stratified analyses, these associations were stronger in boys (aOR=10.9 [95% CI: 1.4-86.0]) than in girls (aOR=2.8 [95% CI: 0.4-21.3]), although the BPA by sex interaction term was not significant (p=0.25).

CONCLUSION

We found evidence that higher urinary BPA concentrations were associated with ADHD in U.S. children; these associations were stronger in boys than in girls. Considering the widespread use of BPA and growing literature on neurobehavioral effects of BPA in children, further study is warranted to determine if reducing exposure to BPA may represent an important avenue for ADHD prevention.

Adverse effects of bisphenol A (BPA) on the dopamine system in two distinct cell models and corpus striatum of the Sprague-Dawley rat

The aim of this study was to examine the effects of bisphenol A (BPA) on the brain dopamine (DA) system utilizing both in vitro models (GH3 cells, a rat pituitary cell line, and SH-SY5Y cells, a human neuroblastoma cell line) and an animal model such as Sprague-Dawley (SD) rats. First, cellular DA uptake was measured 2 or 8 h following BPA exposure (0.1-400 μM) in SH-SY5Y cells, where a significant increase in DA uptake was noted. BPA exerted no marked effect on dopamine active transporter levels in GH3 cells exposed for 8 or 24 h. However, SH-SY5Y cells displayed an increase in dopamine transporter (DAT) levels following 24 h of exposure to BPA. In contrast to DAT levels, BPA exposure produced no marked effect on DA D1 receptor levels in SH-SY5Y cells, yet a significant decrease in GH3 cells following both 8- and 24-h exposure periods was noted, suggesting that BPA exerts differential effects dependent upon cell type. BPA produced no significant effects on prolactin levels at 2 h, but a marked fall occurred at 24 h of exposure in GH3 cells. Finally, to examine the influence of dietary developmental exposure to BPA on brain DA levels in F1 offspring, SD rats were exposed to BPA (0.5-20 mg/kg) through maternal transfer and/or diet and striatal DA levels were measured on postnatal day (PND) 60 using high-performance liquid chromatography (HPLC). Data demonstrated that chronic exposure to BPA did not significantly alter striatal DA levels in the SD rat.

Neonatal Benzo[a]pyrene Exposure Induces Oxidative Stress and DNA Damage Causing Neurobehavioural Changes during the Early Adolescence Period in Rats

Humans are exposed to polycyclic aromatic hydrocarbons (PAHs) by ingestion of contaminated food and water. Prenatal exposure to benzo[a]pyrene (B[a]P) like PAHs through the placental barrier and neonatal exposure by breast milk and the environment may affect early brain development. In the present study, single intracisternal administration of B[a]P (0.2 and 2.0 µg/kg body weight) to male Wistar rat pups at postnatal day 5 (PND5) was carried out to study its specific effect on neonatal brain development and its consequences at PND30. B[a]P administration showed a significant increase in exploratory and anxiolytic-like behaviour with elevated hippocampal lipid peroxidation and protein oxidation at PND30. Further, DNA damage was estimated in vitro (Neuro2a and C6 cell lines) by the comet assay, and oxidative DNA damage of hippocampal sections was measured in vivo following exposure to B[a]P. DNA strand breaks (single and double) significantly increased due to B[a]P at PND30 in hippocampal neurons and increased the nuclear tail moment in Neuro2a cells. Hippocampal 8-oxo-2′-deoxyguanosine production was significantly elevated showing expression of more TUNEL-positive cells in both doses of B[a]P. Histological studies also revealed a significant reduction in mean area and perimeter of hippocampal neurons in rats treated with B[a]P 2.0 μg/kg, when compared to naïve and control rats. B[a]P significantly increased anxiolytic-like behaviour and oxidative DNA damage in the hippocampus causing apoptosis that may lead to neurodegeneration in adolescence. The findings of the present study address the potential role of B[a]P in inducing oxidative stress-mediated neurodegeneration in the hippocampus through oxidative DNA damage in the early adolescence period of rats.

Bisphenol A exposure and behavioral problems among inner city children at 7-9 years of age

BACKGROUND

Bisphenol A (BPA) is a ubiquitous endocrine disrupting compound. Several experimental and epidemiological studies suggest that gestational BPA exposure can lead to neurodevelopmental and behavioral problems in early-life, but results have been inconsistent. We previously reported that prenatal BPA exposure may affect child behavior and differently among boys and girls at ages 3-5 years.

OBJECTIVES

We investigated the association of prenatal and early childhood BPA exposure with behavioral outcomes in 7-9 year old minority children and hypothesized that we would observe the same sex-specific pattern observed at earlier ages.

METHODS

African-American and Dominican women enrolled in an inner-city prospective cohort study and their children were followed from mother's pregnancy through children's age 7-9 years. Women during the third trimester of pregnancy and children at ages 3 and 5 years provided spot urine samples. BPA exposure was categorized by tertiles of BPA urinary concentrations. The Child Behavioral Checklist (CBCL) was administered at ages 7 and 9 to assess multiple child behavior domains. Associations between behavior and prenatal (maternal) BPA concentrations and behavior and postnatal (child) BPA concentration were assessed via Poisson regression in models stratified by sex. These models accounted for potential confounders including prenatal or postnatal urinary BPA concentrations, child age at CBCL assessment, ethnicity, gestational age, maternal intelligence, maternal education and demoralization, quality of child's home environment, prenatal environmental tobacco smoke exposure, and prenatal mono-n-butyl phthalate concentration.

RESULTS

The direction of the associations differed between boys and girls. Among boys (n=115), high prenatal BPA concentration (upper tertile vs. lower two tertiles) was associated with increased internalizing (β=0.41, p<0.0001) and externalizing composite scores (β=0.40, p<0.0001) and with their corresponding individual syndrome scales. There was a general decrease in scores among girls that was significant for the internalizing composite score (β=-0.17, p=0.04) (n=135). After accounting for possible selection bias, the results remained consistent for boys. Conversely, high postnatal BPA concentration was associated with increased behaviors on both the internalizing composite (β=0.30, p=0.0002) and externalizing composite scores (β=0.33, p<0.0001) and individual subscores in girls but fewer symptoms in boys. These results remained significant in girls after accounting for selection bias.

CONCLUSION

These results suggest BPA exposure may affect childhood behavioral outcomes in a sex-specific manner and differently depending on timing of exposure.

Multigenerational and transgenerational effects of endocrine disrupting chemicals: A role for altered epigenetic regulation?

Increasing evidence has highlighted the critical role of early life environment in shaping the future health outcomes of an individual. Moreover, recent studies have revealed that early life perturbations can affect the health of subsequent generations. Hypothesized mechanisms of multi- and transgenerational inheritance of abnormal developmental phenotypes include epigenetic misregulation in germ cells. In this review, we will focus on the available data demonstrating the ability of endocrine disrupting chemicals (EDCs), including bisphenol A (BPA), phthalates, and parabens, to alter epigenetic marks in rodents and humans. These epigenetic marks include DNA methylation, histone post-translational modifications, and non-coding RNAs. We also review the current evidence for multi- and transgenerational inheritance of abnormal developmental changes in the offspring following EDC exposure. Based on published results, we conclude that EDC exposure can alter the mouse and human epigenome, with variable tissue susceptibilities. Although increasing data suggest that exposure to EDCs is linked to transgenerational inheritance of reproductive, metabolic, or neurological phenotypes, more studies are needed to validate these observations and to elucidate further whether these developmental changes are directly associated with the relevant epigenetic alterations.

Bisphenol-A exposure during adolescence leads to enduring alterations in cognition and dendritic spine density in adult male and female rats

We have previously demonstrated that adolescent exposure of rats to bisphenol-A (BPA), an environmental endocrine disrupter, increases anxiety, impairs spatial memory, and decreases dendritic spine density in the CA1 region of the hippocampus (CA1) and medial prefrontal cortex (mPFC) when measured in adolescents in both sexes. The present study examined whether the behavioral and morphological alterations following BPA exposure during adolescent development are maintained into adulthood. Male and female, adolescent rats received BPA, 40μg/kg/bodyweight, or control treatments for one week. In adulthood, subjects were tested for anxiety and locomotor activity, spatial memory, non-spatial visual memory, and sucrose preference. Additionally, stress-induced serum corticosterone levels and dendritic spine density in the mPFC and CA1 were measured. BPA-treated males, but not females, had decreased arm visits on the elevated plus maze, but there was no effect on anxiety. Non-spatial memory, object recognition, was also decreased in BPA treated males, but not in females. BPA exposure did not alter spatial memory, object placement, but decreased exploration during the tasks in both sexes. No significant group differences in sucrose preference or serum corticosterone levels in response to a stress challenge were found. However, BPA exposure, regardless of sex, significantly decreased spine density of both apical and basal dendrites on pyramidal cells in CA1 but had no effect in the mPFC. Current data are discussed in relation to BPA dependent changes, which were present during adolescence and did, or did not, endure into adulthood. Overall, adolescent BPA exposure, below the current reference safe daily limit set by the U.S.E.P.A., leads to alterations in some behaviors and neuronal morphology that endure into adulthood.

Analysis of the developing neural system using an in vitro model by Raman spectroscopy

We developed an in vitro model of early neural cell development.

A novel model for neuroendocrine toxicology: neurobehavioral effects of BPA exposure in a prosocial species, the prairie vole (Microtus ochrogaster)

Impacts on brain and behavior have been reported in laboratory rodents after developmental exposure to bisphenol A (BPA), raising concerns about possible human effects. Epidemiological data suggest links between prenatal BPA exposure and altered affective behaviors in children, but potential mechanisms are unclear. Disruption of mesolimbic oxytocin (OT)/vasopressin (AVP) pathways have been proposed, but supporting evidence is minimal. To address these data gaps, we employed a novel animal model for neuroendocrine toxicology: the prairie vole (Microtus ochrogaster), which are more prosocial than lab rats or mice. Male and female prairie vole pups were orally exposed to 5-μg/kg body weight (bw)/d, 50-μg/kg bw/d, or 50-mg/kg bw/d BPA or vehicle over postnatal days 8-14. Subjects were tested as juveniles in open field and novel social tests and for partner preference as adults. Brains were then collected and assessed for immunoreactive (ir) tyrosine hydroxylase (TH) (a dopamine marker) neurons in the principal bed nucleus of the stria terminalis (pBNST) and TH-ir, OT-ir, and AVP-ir neurons in the paraventricular nucleus of the hypothalamus (PVN). Female open field activity indicated hyperactivity at the lowest dose and anxiety at the highest dose. Effects on social interactions were also observed, and partner preference formation was mildly inhibited at all dose levels. BPA masculinized principal bed nucleus of the stria terminalis TH-ir neuron numbers in females. Additionally, 50-mg/kg bw BPA-exposed females had more AVP-ir neurons in the anterior PVN and fewer OT-ir neurons in the posterior PVN. At the 2 lowest doses, BPA eliminated sex differences in PVN TH-ir neuron numbers and reversed this sex difference at the highest dose. Minimal behavioral effects were observed in BPA-exposed males. These data support the hypothesis that BPA alters affective behaviors, potentially via disruption of OT/AVP pathways.

Adolescent bisphenol-A exposure decreases dendritic spine density: role of sex and age

Bisphenol-A (BPA), a common environmental endocrine disruptor, modulates estrogenic, androgenic, and antiandrogenic effects throughout the lifespan. We recently showed that low dose BPA exposure during adolescence increases anxiety and impairs spatial memory independent of sex. In this study, six week old Sprague Dawley rats (n=24 males, n=24 females) received daily subcutaneous injections (40 µg/kg bodyweight) of BPA or vehicle for one week. Serum corticosterone levels in response to a 1 h restraint stress and spine density were examined at age 7 (cohort 1) and 11 (cohort 2) weeks. Adolescent BPA exposure did not alter stress dependent corticosterone responses but decreased spine density on apical and basal dendrites of pyramidal cells in the medial prefrontal cortex (mPFC) and hippocampal CA1 region (CA1). Sex differences in spine density were observed on basal dendrites of the mPFC and CA1 with females having greater spine density than males. This sex difference was further augmented by both age and treatment, with results indicating that BPA-dependent decreases in spine density were more pronounced in males than females on mPFC basal dendrites. Importantly, the robust neuronal alterations were observed in animals exposed to BPA levels below the current U.S.E.P.A. recommended safe daily limit. These results are the first demonstrating that BPA given during adolescence leads to enduring effects on neural morphology at adulthood. Given that humans are routinely exposed to low levels of BPA through a variety of sources, the decreased spine density reported in both male and female rats after BPA exposure warrants further investigation.

Prenatal and early childhood bisphenol A concentrations and behavior in school-aged children

INTRODUCTION

Early life exposure to bisphenol A (BPA), an endocrine disrupting chemical used in some food and beverage containers, receipts, and dental sealants, has been associated with anxiety and hyperactivity in animal studies. A few human studies also show prenatal and childhood BPA exposure to be associated with behavior problems in children.

METHODS

We measured BPA in urine from mothers during pregnancy and children at 5 years of age (N=292). Child behavior was assessed by mother and teacher report at age 7 years and direct assessment at age 9 years.

RESULTS

Prenatal urinary BPA concentrations were associated with increased internalizing problems in boys, including anxiety and depression, at age 7. No associations were seen with prenatal BPA concentrations and behaviors in girls. Childhood urinary BPA concentrations were associated with increased externalizing behaviors, including conduct problems, in girls at age 7 and increased internalizing behaviors and inattention and hyperactivity behaviors in boys and girls at age 7.

CONCLUSIONS

This study adds to the existing literature showing associations of early life BPA exposure with behavior problems, including anxiety, depression, and hyperactivity in children. Additional information about timing of exposure and sex differences in effect is still needed.

Bisphenol A in relation to behavior and learning of school-age children

BACKGROUND

Bisphenol A (BPA) has been shown to affect brain and behavior in rodents and nonhuman primates, but there are few studies focusing on its relationship to human neurobehavior. We aimed to investigate the relationship between environmental exposure to BPA and childhood neurobehavior.

METHODS

Urinary BPA concentrations and behavioral and learning characteristics were assessed in a general population of 1,089 children, aged 8-11 years. The main outcome measures were the Child Behavior Checklist (CBCL) and the Learning Disability Evaluation Scale (LDES).

RESULTS

Urinary levels of BPA were positively associated with the CBCL total problems score and negatively associated with the learning quotient from the LDES. The linear association with the CBCL anxiety/depression score and the quadratic association with the LDES listening score were significant after correction for multiple comparisons.

CONCLUSIONS

Environmental exposure to BPA might be associated with childhood behavioral and learning development. The results suggest possible nonmonotonic relationships.

Hepatic and renal functions in growing male rats after bisphenol A and octylphenol exposure

This study aimed to determine the effects of 13-week bisphenol A (BPA) and octylphenol (OP) exposure on the liver, kidney, and spleen of growing male rats. A total of 29 male Wistar rats aged 4–5 weeks were divided into five groups. The treatment groups were given low-dose (125 mg/kg bw/day) or high-dose (250 mg/kg bw/day) BPA or OP. These compounds were dissolved in corn oil and given via oral route for 13 weeks. Rats in the control group received corn oil for 13 weeks, as well. After 13 weeks of treatment, blood samples were analyzed for biochemical parameters. Tissue samples from the liver, kidney, and spleen were histopathologically and histomorphometrically examined. Liver tissue specimens were also stained by immunohistochemically; the number of apoptotic cells was counted, and the apoptotic indices were calculated. There were significant differences between the control and treatment groups with respect to the following parameters: body weight, relative left kidney weight, and total protein, glucose, and alkaline phosphatase levels. Edema and parenchymal degeneration in the liver and tubular degeneration in the kidney were more frequent in the treatment groups. The control and treatment groups were comparable with respect to the frequency of histopathological lesions in the spleen. Glomerular histomorphometry revealed no significant differences between the control and treatment groups. No significant differences existed between the control and treatment groups with respect to the number of apoptotic cells and apoptotic indices. Subchronic exposure to BPA and OP induced functional and structural changes in the liver, kidney, and spleen of growing male rats.

Prolonged exposure to a low-dose of bisphenol A increases spontaneous motor activity in adult male rats

We investigated the effects of bisphenol A (BPA), an environmental endocrine-disrupting chemical, on spontaneous motor activity in adult male rats. The rats were implanted intraperitoneally with mini-osmotic pumps containing either BPA (50 μg/kg body weight per day) in sesame oil (BPA-treated group) or sesame oil only (vehicle-treated group). Spontaneous motor activity during a 24-h period was measured over 5 days from day 9 to day 13 after implantation using an animal movement analysis system. Spontaneous motor activity during the last 2 h of the dark phase and during the first 1-h of the light phase was increased in the BPA-treated group. Total spontaneous motor activity during the 12-h light phase, but not the 12-h dark phase, was higher in the BPA-treated group than in the vehicle-treated group. These findings suggest that BPA may induce hyperactivity in adult male rats during the 12-h light phase, especially during the 2 h immediately preceding sleep-onset and 1 h immediately following sleep-onset.

Urinary bisphenol A and obesity in U.S. children

Childhood obesity, a major public health problem, can lead to cardiovascular disease in adulthood. Studies have implicated exposure to bisphenol A (BPA), a commonly used chemical, in the development of obesity in adults. However, literature is limited on this association in children. We examined the association between urinary BPA and obesity in children aged 6-18 years from the National Health and Nutrition Examination Survey (2003-2008). The primary exposure was urinary BPA and the outcome was obesity, defined as the ≥ 95th percentile of body mass index specific for age and sex. We found a positive association between increasing levels of urinary BPA and obesity, independent of age, sex, race/ethnicity, education, physical activity, serum cotinine, and urinary creatinine. Compared with children in the lowest quartile of BPA (<1.5 ng/mL), children in the highest quartile (>5.4 ng/mL) had a multivariable odds ratio for obesity of 2.55 (95% confidence interval (CI): 1.65, 3.95) (Ptrend < 0.01). The observed positive association was predominantly present in boys (odds ratio = 3.80, 95% CI: 2.25, 6.43) (Ptrend < 0.001) and in non-Hispanic whites (odds ratio = 5.87, 95% CI: 2.15, 16.05) (Ptrend < 0.01). In a representative sample of children, urinary BPA was associated with obesity, predominantly in non-Hispanic white boys, independent of major risk factors.

Exposure to widespread environmental toxicants and children's cognitive development and behavioral problems

Nowadays a special attention is focused on prenatal and childhood exposures to a variety of contaminants in the environment, especially toxicants widely present in the environment and their impact on children's health and neurodevelopment. This article aims at evaluating the impact of exposure to several widespread toxicants including: polycyclic aromatic hydrocarbons (PAHs), phthalates, bisphenol A, brominated flame retardants and gas cooking on children's cognitive development and behavioral problems by reviewing most recent published literature. Epidemiological studies focusing on exposure to widespread toxicants and children's development for the last eleven years were identified by a search of the PubMed, Medline, Ebsco and Toxnet literature bases. The combination of following key words was used: 1) referring to the exposure: pregnancy, prenatal exposure, postnatal exposure, gas cooking, exposure to phthalates, bisphenol A, brominated flame retardants, PAHs and 2) referring to outcome: neurodevelopment, neurobehavior, psychomotor development, behavioral problems, cognitive development, mental health, school achievements, learning abilities. The results from the presented studies suggest that there are strong and rather consistent indications that the developing nervous system is particularly vulnerable to insult from low levels of exposure to widespread environmental contaminants such as: phthalates, bisphenol A, brominated flame retardants, polycyclic aromatic hydrocarbons, gas cooking. Considering the suggested health effects, more epidemiologic data is urgently needed and, in the meantime, precautionary policies must be implemented.

[Endocrine disruptors: echoes of congress of Endocrinology in 2012]

The increased prevalence of certain diseases, along with the development of new technologies and industrialization raised the possibility of the involvement of environmental factors, industrial products, nutritional factors, infections, drugs... and endocrine disruptors. These factors may interfere via signaling pathways specific to the organism. Endocrine Disrupting Chemicals (EDCs) have been redefined by the Endocrine Society in 2012 as "exogenous chemical, or mixture of chemicals, that can interfere with any aspect of hormone action". They have therefore potentially deleterious effects on development, growth, metabolism, reproduction, the nervous, immune and cardiovascular systems. Therefore, they constitute a real public health issue. Their long half-life may explain delayed effects and their often lipophilic character may promote maternofetal transmission. Except diethylstilbestrol (DES), few formal proofs have been made on the direct role of EDCs ; arguments are based on cross-sectional studies, in vitro models and animal models. Basic research puts insight into mechanisms of action of EDCs but many questions remain unanswered. Epidemiological data are difficult to interpret because of interindividual differences in susceptibility to EDCs and of nonlinear/nonmonotonique action (as opposed to toxic dose effect), multiple interactions between environmental agents (additive effects and/or synergistic and/or antagonists), the role of the window of exposure, latency, and the possibility of transgenerational effects.

Plastics derived endocrine disruptors (BPA, DEHP and DBP) induce epigenetic transgenerational inheritance of obesity, reproductive disease and sperm epimutations

Environmental compounds are known to promote epigenetic transgenerational inheritance of adult onset disease in subsequent generations (F1–F3) following ancestral exposure during fetal gonadal sex determination. The current study was designed to determine if a mixture of plastic derived endocrine disruptor compounds bisphenol-A (BPA), bis(2-ethylhexyl)phthalate (DEHP) and dibutyl phthalate (DBP) at two different doses promoted epigenetic transgenerational inheritance of adult onset disease and associated DNA methylation epimutations in sperm. Gestating F0 generation females were exposed to either the “plastics” or “lower dose plastics” mixture during embryonic days 8 to 14 of gonadal sex determination and the incidence of adult onset disease was evaluated in F1 and F3 generation rats. There were significant increases in the incidence of total disease/abnormalities in F1 and F3 generation male and female animals from plastics lineages. Pubertal abnormalities, testis disease, obesity, and ovarian disease (primary ovarian insufficiency and polycystic ovaries) were increased in the F3 generation animals. Kidney and prostate disease were only observed in the direct fetally exposed F1 generation plastic lineage animals. Analysis of the plastics lineage F3 generation sperm epigenome previously identified 197 differential DNA methylation regions (DMR) in gene promoters, termed epimutations. A number of these transgenerational DMR form a unique direct connection gene network and have previously been shown to correlate with the pathologies identified. Observations demonstrate that a mixture of plastic derived compounds, BPA and phthalates, can promote epigenetic transgenerational inheritance of adult onset disease. The sperm DMR provide potential epigenetic biomarkers for transgenerational disease and/or ancestral environmental exposures.