Prenatal exposure to benzophenone-3 (BP-3) induces apoptosis, disrupts estrogen receptor expression and alters the epigenetic status of mouse neurons

The exposure to UV filters: Prevalence, effects, possible molecular mechanisms of action and interactions within mixtures

Substances that can absorb sunlight and harmful UV radiation such as organic UV filters are widely used in cosmetics and other personal care products. Since humans use a wide variety of chemicals for multiple purposes it is common for UV filters to co-occur with other substances either in human originating specimens or in the environment. There is increasing interest in understanding such co-occurrence in form of potential synergy, antagonist, or additive effects of biological systems. This review focuses on the collection of data about the simultaneous occurrence of UV filters oxybenzone (OXYB), ethylexyl-methoxycinnamate (EMC) and 4-methylbenzylidene camphor (4-MBC) as well as other classes of chemicals (such as pesticides, bisphenols, and parabens) to understand better any such interactions considering synergy, additive effect and antagonism. Our analysis identified >20 different confirmed synergies in 11 papers involving 16 compounds. We also highlight pathways (such as transcriptional activation of estrogen receptor, promotion of estradiol synthesis, hypothalamic-pituitary-gonadal (HPG) axis, and upregulation of thyroid-hormone synthesis) and proteins (such as Membrane Associated Progesterone Receptor (MAPR), cytochrome P450, and heat shock protein 70 (Hsp70)) that can act as important key nodes for such potential interactions. This article aims to provide insight into the molecular mechanisms on how commonly used UV filters act and may interact with other chemicals.

A review of sources, pathways, and toxic effects of human exposure to benzophenone ultraviolet light filters

Benzophenone ultraviolet light filters (BPs) are high-production-volume chemicals extensively used in personal care products, leading to widespread human exposure. Given their estrogenic properties, the potential health risks associated with exposure to BPs have become a public health concern. This review aims to summarize sources and pathways of exposure to BPs and associated health risks. Dermal exposure, primarily through the use of sunscreens, constitutes a major pathway for BP exposure. At a recommended application rate, dermal exposure of BP-3 via the application of sunscreens may reach or exceed the suggested reference dose. Other exposure pathways to BPs, such as drinking water, seafood, and packaged foods, contribute minimal to the overall dose. Inhalation is a minor pathway of exposure; however, its contribution cannot be ignored. Human exposure to BPs is an order of magnitude higher in North America than in Asia and Europe. Studies conducted on laboratory animals and cells have consistently demonstrated the toxic effects of BP exposure. BPs are estrogenic and elicit reproductive and developmental toxicities. Furthermore, neurotoxicity, hepatotoxicity, nephrotoxicity, and carcinogenicity have been reported from chronic BP exposure. In addition to animal and cell studies, epidemiological investigations have identified associations between BPs and couples' fecundity and other reproductive disorders, as well as adverse birth outcomes. Further studies are urgently needed to understand the risks posed by BPs on human health.

Long-term effects of embryonic exposure to benzophenone-3 on neurotoxicity and behavior of adult zebrafish

Benzophenone-3 (BP-3) is the most widely used ultraviolet filter (UV filter) in industries to avoid UV radiation damage. BP-3 is added to most sunscreens to protect the skin, hair, and lips from sun rays. It results in continuous discharge into aquatic environments, leading to aquatic biota and human's continuous exposure. Consequences of BP-3 exposure on the physiology and behavior of aquatic animals, mainly zebrafish, have been investigated, including their neurotoxic effects. However, little is known about its consequences in long-term developmental endpoints. This study aimed to investigate the long-term effects of embryonic BP-3 exposure on biomarkers of neurotoxicity in zebrafish. For this, we exposed embryos to 5, 10, and 20 μg∙L-1 BP-3 concentration and let fish grow to adulthood (5mpf). We evaluated anxiety-like behavior, social preference, aggressiveness, and enzymatic activity of the antioxidant defenses system and neurotoxic biomarkers (Glutathione S-transferase -GST, catalase -CAT, and acetylcholinesterase -AChE) in adult zebrafish. Enzymatic activities were also investigated in larvae immediately after BP-3 exposure. Animals early exposed to BP-3 presented anxiety-like behaviors and decreased social preference, but aggressiveness was not altered. In general, exposure to BP-3 leads to altered enzymatic activity, which persists into adulthood. GST activity increased in embryos and adults, while CAT activity decreased in both life stages. AChE activity enhanced only at the larval stage (96 hpf). The long-term behavioral and biochemical effects of BP-3 highlight the need for abolishing or restricting the compound from personal care products, which are continually disposed into the environment and threaten the biota and human health.

Early-Life Exposure to a Mixture of Phenols and Phthalates in Relation to Child Social Behavior: Applying an Evidence-Based Prioritization to a Cohort with Improved Exposure Assessment

BACKGROUND

Previous studies aiming at relating exposure to phenols and phthalates with child social behavior characterized exposure using one or a few spot urine samples, resulting in substantial exposure misclassification. Moreover, early infancy exposure was rarely studied.

OBJECTIVES

We aimed to examine the associations of phthalates and phenols with child social behavior in a cohort with improved exposure assessment and to a priori identify the chemicals supported by a higher weight of evidence.

METHODS

Among 406 mother-child pairs from the French Assessment of Air Pollution exposure during Pregnancy and Effect on Health (SEPAGES) cohort, 25 phenols/phthalate metabolites were measured in within-subject pools of repeated urine samples collected at the second and third pregnancy trimesters (∼ 21 samples/trimester) and at 2 months and 1-year of age (∼ 7 samples/period). Social behavior was parent-reported at 3 years of age of the child using the Social Responsiveness Scale (SRS). A structured literature review of the animal and human evidence was performed to prioritize the measured phthalates/phenols based on their likelihood to affect social behavior. Both adjusted linear regression and Bayesian Weighted Quantile Sum (BWQS) regression models were fitted. False discovery rate (FDR) correction was applied only to nonprioritized chemicals.

RESULTS

Prioritized compounds included bisphenol A, bisphenol S, triclosan (TCS), diethyl-hexyl phthalate (Σ DEHP ), mono-ethyl phthalate (MEP), mono-n -butyl phthalate (MnBP), and mono-benzyl phthalate (MBzP). With the exception of bisphenols, which showed a mixed pattern of positive and negative associations in pregnant mothers and neonates, few prenatal associations were observed. Most associations were observed with prioritized chemicals measured in 1-y-old infants: Each doubling in urinary TCS (β = 0.78 ; 95% CI: 0.00, 1.55) and MEP (β = 0.92 ; 95% CI: - 0.11 , 1.96) concentrations were associated with worse total SRS scores, whereas MnBP and Σ DEHP were associated with worse Social Awareness (β = 0.25 ; 95% CI: 0.01, 0.50) and Social Communication (β = 0.43 ; 95% CI: - 0.02 , 0.89) scores, respectively. BWQS also suggested worse total SRS [Beta  1 = 1.38 ; 95% credible interval (CrI): - 0.18 , 2.97], Social Awareness (Beta  1 = 0.37 ; 95% CrI: 0.06, 0.70), and Social Communication (Beta  1 = 0.91 ; 95% CrI: 0.31, 1.53) scores per quartile increase in the mixture of prioritized compounds assessed in 1-y-old infants. The few associations observed with nonprioritized chemicals did not remain after FDR correction, with the exception of benzophenone-3 exposure in 1-y-old infants, which was suggestively associated with worse Social Communication scores (corrected p = 0.07 ).

DISCUSSION

The literature search allowed us to adapt our statistical analysis according to the weight of evidence and create a corpus of experimental and epidemiological knowledge to better interpret our findings. Early infancy appears to be a sensitive exposure window that should be further investigated. https://doi.org/10.1289/EHP11798.

Benzophenone-3 causes oxidative stress in the brain and impairs aversive memory in adult zebrafish

Oxybenzone (BP-3) is an ultraviolet (UV) filter widely used in industries that is directly or indirectly released into the aquatic environment. However, little is known about its effects on brain performance. Here, we investigated whether BP-3 exposure affects the redox imbalance in zebrafish and how they respond to a task that requires memory of an aversive situation. Fish were exposed to BP-3 10 and 50 μg L-1 for 15 days and then tested using an associative learning protocol with electric shock as a stimulus. Brains were extracted for reactive oxygen species (ROS) measurement and qPCR analysis of antioxidant enzyme genes. ROS production increased for exposed animals, and catalase (cat) and superoxide dismutase 2 (sod 2) were upregulated. Furthermore, learning and memory were reduced in zebrafish exposed to BP-3. These results suggested that BP-3 may lead to a redox status imbalance, causing impaired cognition and reinforcing the need to replace the toxic UV filters with filters that minimize environmental effects.

Benzophenone-3: Comprehensive review of the toxicological and human evidence with meta-analysis of human biomonitoring studies

BACKGROUND

Benzophenone-3 (BP-3) and its major metabolite benzophenone-1 (BP-1) are widely used as UV filters in sunscreens and cosmetics to prevent sunburn and skin damage, or as stabilizers to prevent photodegradation in many commercial products. As a result, their presence is ubiquitous in the environment, wildlife and humans. Based on endocrine disruption concerns, international regulatory agencies are performing a closer evaluation.

OBJECTIVE AND METHODS

This work aimed to comprehensively review the available human relevant evidence for safety issues in MEDLINE/PubMed in order to create a structured database of studies, as well as to conduct an integrative analysis as part of the Human Biomonitoring for Europe (HBM4EU) Initiative.

RESULTS

A total of 1,635 titles and abstracts were screened and 254 references were evaluated and tabulated in detail, and classified in different categories: i) exposure sources and predictors; ii) human biomonitoring (HBM) exposure levels to perform a meta-analysis; iii) toxicokinetic data in both experimental animals and humans; iv) in vitro and in vivo rodent toxicity studies; and v) human data on effect biomarkers and health outcomes. Our integrative analysis showed that internal peak BP-3 concentrations achieved after a single whole-body application of a commercially available sunscreen (4% w/w) may overlap with concentrations eliciting endocrine disrupting effects in vitro, and with internal concentrations causing in vivo adverse female reproductive effects in rodents that were supported by still limited human data. The adverse effects in rodents included prolonged estrous cycle, altered uterine estrogen receptor gene expression, endometrium hyperplasia and altered proliferation and histology of the mammary gland, while human data indicated menstrual cycle hormonal alterations and increased risk of uterine fibroids and endometriosis. Among the modes of action reported (estrogenic, anti-androgenic, thyroid, etc.), BP-3 and especially BP-1 showed estrogenic activity at human-relevant concentrations, in agreement with the observed alterations in female reproductive endpoints. The meta-analysis of HBM studies identified a higher concern for North Americans, showing urinary BP-3 concentrations on average 10 and 20 times higher than European and Asian populations, respectively.

DISCUSSION AND CONCLUSIONS

Our work supports that these benzophenones present endocrine disrupting properties, endorsing recent European regulatory efforts to limit human exposure. The reproducible and comprehensive database generated may constitute a point of departure in future risk assessments to support regulatory initiatives. Meanwhile, individuals should not refrain from sunscreen use. Commercially available formulations using inorganic UV filters that are practically not absorbed into systemic circulation may be recommended to susceptible populations.

Emerging Evidence on Membrane Estrogen Receptors as Novel Therapeutic Targets for Central Nervous System Pathologies

Nuclear- and membrane-initiated estrogen signaling cooperate to orchestrate the pleiotropic effects of estrogens. Classical estrogen receptors (ERs) act transcriptionally and govern the vast majority of hormonal effects, whereas membrane ERs (mERs) enable acute modulation of estrogenic signaling and have recently been shown to exert strong neuroprotective capacity without the negative side effects associated with nuclear ER activity. In recent years, GPER1 was the most extensively characterized mER. Despite triggering neuroprotective effects, cognitive improvements, and vascular protective effects and maintaining metabolic homeostasis, GPER1 has become the subject of controversy, particularly due to its participation in tumorigenesis. This is why interest has recently turned toward non-GPER-dependent mERs, namely, mERα and mERβ. According to available data, non-GPER-dependent mERs elicit protective effects against brain damage, synaptic plasticity impairment, memory and cognitive dysfunctions, metabolic imbalance, and vascular insufficiency. We postulate that these properties are emerging platforms for designing new therapeutics that may be used in the treatment of stroke and neurodegenerative diseases. Since mERs have the ability to interfere with noncoding RNAs and to regulate the translational status of brain tissue by affecting histones, non-GPER-dependent mERs appear to be attractive targets for modern pharmacotherapy for nervous system diseases.

Lifetime exposure to benzophenone-3 at an environmentally relevant concentration leads to female-biased social behavior and cognition deficits in zebrafish

Benzophenone-3 (BP3) is an organic UV filter widely used in the commercial formulations of various personal care products. It has been detected ubiquitously in the environment and human tissues. Recently, BP3-induced neurotoxicity has been identified as the main health risk to humans and aquatic organisms. However, most research has been focused on embryonic development, and few studies explore chronic lifetime exposure. In the present study, we evaluated the neurotoxicity of lifetime exposure to an environmentally relevant concentration of BP3 in zebrafish. Our findings revealed that continuous BP3 exposure at 10 μg/L (0.04 μM) from 6 h post fertilization (hpf) to adulthood at 5 months led to female-biased social behavioral deficits and learning and memory impairment. These neurobehavioral effects were characterized by decreased prosocial activities in the social preference test and mirror biting assay, and reduced learning and memory in a T-maze test. Furthermore, these effects were accompanied by female-specific decreases in brain weight and brain dopamine concentration, female-biased decrease of neurogenesis in the telencephalon as well as female-specific increases in apoptotic cells and expression levels of genes and proteins related to the apoptosis pathway in the brain. Our results suggest that BP3-induced social behavior and learning/memory deficits are correlated to the cell loss in the telencephalon region of the zebrafish brain.

Environmentally relevant concentrations of organic (benzophenone-3) and inorganic (titanium dioxide nanoparticles) UV filters co-exposure induced neurodevelopmental toxicity in zebrafish

UV filters, widely used in personal care products, are ubiquitous environmental pollutants detected and pose a significant public health concern. Benzophenone-3 (BP3) and titanium dioxide nanoparticles (nano-TiO₂) are the predominant organic and inorganic UV filters in environmental media. However, few studies have explored the combined developmental neurotoxic (DNT) effects and the underlying mechanisms when co-exposed to BP3 and nano-TiO₂. In the present study, zebrafish (Danio rerio) embryos were exposed to environmentally relevant concentrations of BP3 (10 μg/L), nano-TiO₂ (100 μg/L), and mixtures starting from 6 h post fertilization (hpf), respectively. Developmental indicators and motor behaviors were investigated at various developmental stages. Our results showed that BP3 alone or co-exposed with nano-TiO₂ increased spontaneous movement at 24 hpf, co-exposure decreased touch response at 30 hpf and hatching rate at 60 hpf. Consistent with these motor deficits, co-exposure to BP3 and nano-TiO₂ inhibited relative axon length of primary motor neuron during the early developmental stages, disturbed the expression of axonal growth-related genes at 30 and 48 hpf, increased cell apoptosis on the head region and mRNA levels of apoptosis-related genes, and also increased reactive oxygen species (ROS) levels in zebrafish, suggesting the functional relevance of structural changes. Taken together, our findings demonstrated that BP3 alone or in combination with nano-TiO₂ at environmentally relevant concentrations induced evident neurotoxic effects on the developing embryos in zebrafish.

The analysis of lysine succinylation modification reveals the mechanism of oxybenzone damaging of pakchoi (Brassica rapa L. ssp. chinensis)

Oxybenzone (OBZ), one of a broad spectrum of ultraviolet (UV) absorbents, has been proven to be harmful to both plants and animals, while omics analysis of big data at the molecular level is still lacking. Lysine succinylation (Ksuc) is an important posttranslational modification of proteins that plays a crucial role in regulating the metabolic network in organisms under stress. Here, we report the changes in intracellular Ksuc modification in plants under OBZ stress. A total of 1276 succinylated sites on 507 proteins were identified. Among these sites, 181 modified proteins were hypersulfinylated/succinylated in OBZ-stressed pakchoi leaves. Differentially succinylated proteins (DSPs) are distributed mainly in the chloroplast, cytoplasm, and mitochondria and are distributed mainly in primary metabolic pathways, such as reactive oxygen species (ROS) scavenging, stress resistance, energy generation and transfer, photosynthetic carbon fixation, glycolysis, and the tricarboxylic acid (TCA) cycle. Comprehensive analysis shows that Ksuc mainly changes the carbon flow distribution, enhances the activity of the antioxidant system, affects the biosynthesis of amino acids, and increases the modification of histones. The results of this study first showed the profiling of the Kusc map under OBZ treatment and proposed the adaptive mechanism of pakchoi in response to pollutants and other abiotic stresses at the posttranslational level, which revealed the importance of Ksuc in the regulation of various life activities and provides a reference dataset for future research on molecular function.

Benzophenones alter autophagy and ER stress gene expression in pancreatic beta cells in vitro

Benzophenones (BPs) are endocrine disruptors frequently used in sunscreens and food packaging as UV blockers. Our goal was to assess the effect of benzophenone 2 (BP2) and 3 (BP3) on gene expression related to autophagy process and ER stress response in pancreatic beta cells. To that end, the mouse pancreatic beta cell line MIN6B1 was treated with 10 µM BP2 or BP3 in the presence or absence of the autophagy-inhibitor chloroquine (CQ, 10 µM) or the autophagy-inducer rapamycin (RAPA, 50 nM) during 24 h. BP3 inhibited the expression of the autophagic gene Ulk1, and additional effects were uncovered when autophagy was modified by CQ and RAPA. BP3 counteracted CQ-induced Lamp2 expression but did not compensate CQ-induced Sqstm1/p62 gene transcription, neither BP2. Nevertheless, the BPs did not alter the autophagic flux. In relation to ER stress, BP3 inhibited unspliced and spliced Xbp1 mRNA levels in the presence or absence of CQ, totally counteracted CQ-induced Chop gene expression, and partially reverted CQ-induced Grp78/Bip mRNA levels, while BP2 also partially inhibited Grp78/Bip mRNA induction by CQ. In conclusion, BPs, principally BP3, affect cellular adaptive responses related to autophagy, lysosomal biogenesis, and ER stress in pancreatic beta cells, indicating that BP exposure could lead to beta cell dysfunction.

Soil degradation kinetics of oxybenzone (Benzophenone-3) and toxicopathological assessment in the earthworm, Eisenia fetida

A preponderance of recent evidence indicates that oxybenzone and other personal-care product chemicals threaten the biota inhabiting various ecological niches. What is understudied is the ecotoxicological impact of oxybenzone, a UV filter in sunscreens and anti-aging products, to terrestrial/soil organisms that are keystone species in these habitats. In the present study, acute exposure (14-day) to oxybenzone resulted in earthworm mortality (LC₅₀ of 364 mg/kg) and growth rate inhibition. Environmentally relevant concentration of oxybenzone (3.64, 7.28 and 36.4 mg/kg) at exposures of 7-day, 14-day, 28-day induced oxidative stress and neurotoxicity followed by perturbations in reproduction processes and changes in vital organs. Decreased levels of superoxide dismutase (SOD) and catalase (CAT) activity were statistically lower than controls (p < 0.05) on day 14 for all three concentrations, while glutathione-s-transferase (GST) activity was significantly elevated from controls on days 7 and 14. On day 28, SOD and CAT activities were either not significantly different from the control or were higher, demonstrating a temporal multiphasic response of anti-oxidant enzymes. GST activity on day 28 was significantly reduced compared to controls. Acetylcholinesterase levels across the three-time points exhibited a complicated behaviour, with every exposure concentration being significantly different from the control. Chronic exposure negatively influences earthworm health status with elevated biomarker values analysed using IBRv2 index. This, in turn, impacted higher levels of hierarchical organization, significantly impairing reproduction and organismal homeostasis at the histological level and manifesting as decreasing cocoon formation and successful hatching events. Thus, the overall findings demonstrate that oxybenzone is toxic to Eisenia fetida at low-level, long-term exposure. Based on the concentration verification analysis and application of the EPA PestDF tool, oxybenzone undergoes single first-order kinetics degradation in OECD soil with DT50 and DT90 as 8.7-28.9 days, respectively.

Neuroepigenetic Changes in DNA Methylation Affecting Diabetes-Induced Cognitive Impairment

Chronic diabetic conditions have been associated with certain cerebral complications, that include neurobehavioral dysfunctional patterns and morphological alterations of neurons, especially the hippocampus. Neuroanatomical studies done by the authors have shown decreased total dendritic length, intersections, dendritic length per branch order and nodes in the CA1 hippocampal region of the diabetic brain as compared to its normal control group, indicating reduced dendritic arborization of the hippocampal CA1 neurons. Epigenetic alterations in the brain are well known to affect age-associated disorders, however its association with the evolving diabetes-induced damage in the brain is still not fully understood. DNA hypermethylation within the neurons, tend to silent the gene expression of several regulatory proteins. The findings in the study have shown an increase in global DNA methylation in palmitic acid-induced lipotoxic Neuro-2a cells as well as within the diabetic mice brain. Inhibiting DNA methylation, restored the levels of HSF1 and certain HSPs, suggesting plausible effect of DNMTs in maintaining the proteostasis and synaptic fidelity. Neuroinflammation, as exhibited by the astrocyte activation (GFAP), were further significantly decreased in the 5-azadeoxycytidine group (DNMT inhibitor). This was further evidenced by decrease in proinflammatory cytokines TNF⍺, IL-6, and mediators iNOS and Phospho-NFkB. Our results suggest that changes in DNA methylation advocate epigenetic dysregulation and its involvement in disrupting the synaptic exactitude in the hippocampus of diabetic mice model, providing an insight into the pathophysiology of diabetes-induced neuroepigenetic changes.

Effect of Iron Complex Source on MWWTP Effluent Treatment by Solar Photo-Fenton: Micropollutant Degradation, Toxicity Removal and Operating Costs

Benzophenone-3, fipronil and propylparaben are micropollutants that are potential threats to ecosystems and have been detected in aquatic environments. However, studies involving the investigation of new technologies aiming at their elimination from these matrices, such as advanced oxidation processes, remain scarce. In this study, different iron complexes (FeCit, FeEDTA, FeEDDS and FeNTA) were evaluated for the degradation of a mixture of these micropollutants (100 µg L−1 each) spiked in municipal wastewater treatment plant (MWWTP) effluent at pH 6.9 by solar photo-Fenton. Operational parameters (iron and H2O2 concentration and Fe/L molar ratio) were optimized for each complex. Degradation efficiencies improved significantly by increasing the concentration of iron complexes (1:1 Fe/L) from 12.5 to 100 µmol L−1 for FeEDDS, FeEDTA and FeNTA. The maximum degradation reached with FeCit for all iron concentrations was limited to 30%. Different Fe/L molar ratios were required to maximize the degradation efficiency for each ligand: 1:1 for FeNTA and FeEDTA, 1:3 for FeEDDS and 1:5 for FeCit. Considering the best Fe/L molar ratios, higher degradation rates were reached using 5.9 mmol L−1 H2O2 for FeNTA and FeEDTA compared to 1.5 and 2.9 mmol L−1 H2O2 for FeEDDS and FeCit, respectively. Acute toxicity to Canton S. strain D. melanogaster flies reduced significantly after treatment for all iron complexes, indicating the formation of low-toxicity by-products. FeNTA was considered the best iron complex source in terms of the kinetic constant (0.10 > 0.063 > 0.051 > 0.036 min−1 for FeCit, FeNTA, FeEDTA and FeEDDS, respectively), organic carbon input and cost-benefit (USD 327 m−3 > USD 20 m−3 > USD 16 m−3 > USD 13 m−3 for FeEDDS, FeCit, FeEDTA and FeNTA, respectively) when compared to the other tested complexes.

Does Older Age Modify Associations between Endocrine Disrupting Chemicals and Fecundability?

Urinary concentrations of several endocrine disrupting chemicals, including phthalate metabolites, bisphenol A (BPA), and benzophenone (BP)-type ultraviolet (UV) filters, have been associated with a longer time-to-pregnancy (TTP). Potential modification of these associations by couple’s age has not been studied. TTP was defined as the number of prospectively observed menstrual cycles a couple attempted pregnancy until the occurrence of a human chorionic gonadotropic-detected pregnancy. Urinary concentrations of two BP-type UV filters and three phthalate metabolites were measured at baseline. Fecundability odds ratios (FORs) and 95% confidence intervals (CIs) were estimated for each chemical adjusting for age, body mass index, serum cotinine, creatinine, and accounting for right censoring and left truncation. Models evaluated effect modification between EDC concentrations and TTP by partner’s age, dichotomized at 35 years. Separate models were run for male and female partners. No significant effect modification was observed for any EDC for either partner, but data were suggestive of a longer TTP among females aged ≥35 years, particularly for BP-2 (FOR = 0.61, 95% CI 0.36, 1.05) and 4-hydroxybenzophenone (FOR = 0.71, 95% CI: 0.46, 1.09) reflecting 39% and 29% reductions in fecundability, respectively. We saw no evidence of effect modification by couples’ age on associations between TTP and urinary phthalate or BPA metabolite concentrations. Across the EDCs we examined, we found little evidence that age modifies TTP-exposure associations.

4-hydroxybenzophenone exposure inhibits mouse hippocampal neural stem cell proliferation in vitro by upregulating Cxcl1

Benzophenones are widely used in industry and commonly added in many personal care products. However, the neurotoxicity, in particular neurodevelopmental toxicity, of benzophenone family chemicals and metabolites has not been fully elucidated. Our recent mechanistic study in mice showed that early life exposure to a major benzophenone metabolite, 4-hydroxybenzophenone (4HBP), disrupted endoplasmic reticulum (ER) proteostasis and evoked inflammatory response in hippocampal neural stem cells (NSCs), leading to cognitive dysfunction. Despite so, detailed inflammatory cytokine(s) that possibly mediate this toxicity remains to be defined and validated. In this study, we confirmed that 4HBP treatment inhibited the viability and sphere growth of mouse NSCs in vitro. Importantly, re-interrogation of the transcriptomic data of NSCs treated with 4HBP identified the top upregulated genes, wherein the chemokine Cxcl1 ranked first. Immunofluorescent staining and qRT-PCR validated the robust induction of Cxcl1 on the protein and mRNA levels upon 4HBP treatment. Furthermore, siRNA-mediated knockdown of Cxcl1 transiently blocked its expression and led to enhanced NSCs viability in the presence of 4HBP. Together, these in vitro results indicated that the adverse effect of benzophenones on NSCs is mediated, at least in part, by induction of the chemokine Cxcl1.

Oxybenzone contamination from sunscreen pollution and its ecological threat to Hanauma Bay, Oahu, Hawaii, U.S.A

Hanauma Bay is a 101-acre bay created by the partial collapse of a volcanic cone and once supported a vibrant coral reef system. It is the most popular swimming area in the Hawaiian Islands and has been reported to have averaged between 2.8 and 3.5 million visitors a year between the 1980s and the 2010s, with visitors averaging between 3000-4000 a day and peaking around 10,000-13,000 per day. Concentrations of oxybenzone and other common UV filters were measured in subsurface water samples and in sands from the beach-shower areas in Hanauma Bay. Results demonstrate that beach showers also can be a source of sunscreen environmental contamination. Hydrodynamic modeling indicates that oxybenzone contamination within Hanauma Bay's waters could be retained between 14 and 50 h from a single release event period. Focusing on only oxybenzone, two different Hazard and Risk Assessment analyses were conducted to determine the danger of oxybenzone to Hanauma Bay's coral reef system. Results indicate that oxybenzone contamination poses a significant threat to the wildlife of Hanauma Bay. To recover Hanauma Bay's natural resources to a healthy condition and to satisfactorily conserve its coral reef and sea grass habitats, effective tourism management policies need to be implemented that mitigate the threat of sunscreen pollution.

Prenatal Exposure to Triclocarban Impairs ESR1 Signaling and Disrupts Epigenetic Status in Sex-Specific Ways as Well as Dysregulates the Expression of Neurogenesis- and Neurotransmitter-Related Genes in the Postnatal Mouse Brain

Triclocarban is a highly effective and broadly used antimicrobial agent. Humans are continually exposed to triclocarban, but the safety of prenatal exposure to triclocarban in the context of neurodevelopment remains unknown. In this study, we demonstrated for the first time that mice that had been prenatally exposed to environmentally relevant doses of triclocarban had impaired estrogen receptor 1 (ESR1) signaling in the brain. These mice displayed decreased mRNA and protein expression levels of ESR1 as well as hypermethylation of the Esr1 gene in the cerebral cortex. Prenatal exposure to triclocarban also diminished the mRNA expression of Esr2, Gper1, Ahr, Arnt, Cyp19a1, Cyp1a1, and Atg7, and the protein levels of CAR, ARNT, and MAP1LC3AB in female brains and decreased the protein levels of BCL2, ARNT, and MAP1LC3AB in male brains. In addition, exposure to triclocarban caused sex-specific alterations in the methylation levels of global DNA and estrogen receptor genes. Microarray and enrichment analyses showed that, in males, triclocarban dysregulated mainly neurogenesis-related genes, whereas, in females, the compound dysregulated mainly neurotransmitter-related genes. In conclusion, our data identified triclocarban as a neurodevelopmental risk factor that particularly targets ESR1, affects apoptosis and autophagy, and in sex-specific ways disrupts the epigenetic status of brain tissue and dysregulates the postnatal expression of neurogenesis- and neurotransmitter-related genes.

Pregnancy exposure to synthetic phenols and placental DNA methylation - An epigenome-wide association study in male infants from the EDEN cohort

In utero exposure to environmental chemicals, such as synthetic phenols, may alter DNA methylation in different tissues, including placenta - a critical organ for fetal development. We studied associations between prenatal urinary biomarker concentrations of synthetic phenols and placental DNA methylation. Our study involved 202 mother-son pairs from the French EDEN cohort. Nine phenols were measured in spot urine samples collected between 22 and 29 gestational weeks. We performed DNA methylation analysis of the fetal side of placental tissues using the IlluminaHM450 BeadChips. We evaluated methylation changes of individual CpGs in an adjusted epigenome-wide association study (EWAS) and identified differentially methylated regions (DMRs). We performed mediation analysis to test whether placental tissue heterogeneity mediated the association between urinary phenol concentrations and DNA methylation. We identified 46 significant DMRs (≥5 CpGs) associated with triclosan (37 DMRs), 2,4-dichlorophenol (3), benzophenone-3 (3), methyl- (2) and propylparaben (1). All but 2 DMRs were positively associated with phenol concentrations. Out of the 46 identified DMRs, 7 (6 for triclosan) encompassed imprinted genes (APC, FOXG1, GNAS, GNASAS, MIR886, PEG10, SGCE), which represented a significant enrichment. Other identified DMRs encompassed genes encoding proteins responsible for cell signaling, transmembrane transport, cell adhesion, inflammatory, apoptotic and immunological response, genes encoding transcription factors, histones, tumor suppressors, genes involved in tumorigenesis and several cancer risk biomarkers. Mediation analysis suggested that placental cell heterogeneity may partly explain these associations. This is the first study describing the genome-wide modifications of placental DNA methylation associated with pregnancy exposure to synthetic phenols or their precursors. Our results suggest that cell heterogeneity might mediate the effects of triclosan exposure on placental DNA methylation. Additionally, the enrichment of imprinted genes within the DMRs suggests mechanisms by which certain exposures, mainly to triclosan, could affect fetal development.

UV-filter pollution: current concerns and future prospects

UV-filters are widely used in cosmetics and personal care products to protect users' skin from redamage caused by ultraviolet (UV) radiation from the sun. Globally, an estimated 16,000 to 25,000 tonnes of products containing UV-filters were used in 2014 with modern consumption likely to be much higher. Beyond this use in cosmetics and personal care products, UV-filters are also widely used to provide UV-stability in industrial products such as paints and plastics. This review discusses the main routes by which UV-filters enter aquatic environments and summarises the conclusions of studies from the past 10 years that have investigated the effects of UV-filters on environmentally relevant species including corals, microalgae, fish, and marine mammals. Safety data regarding the potential impact of UV-filters on human health are also discussed. Finally, we explore the challenges surrounding UV-filter removal and research on more environmentally friendly alternatives to current UV-filters.

The toxicological impact of the sunscreen active ingredient octinoxate on the photosynthesis activity of Chlorella sp

Products designed to filter ultraviolet (UV) light are responsible for growing levels of anthropogenic environmental contamination. Octinoxate (ONT) is among the most common UV filtering active ingredients in cosmetics and sunscreens. The present study was designed to evaluate the toxicological effects of ONT on the photosynthetic activity of the Chlorella species of marine microalgae. These analyses identified ONT as a potent photo-toxicant, the effects of which were more pronounced upon light exposure relative to in the dark. Short-term ONT exposure had no effect on photosynthetic electron transport capacity in the dark but did significantly reduce the ribulose-1,5-bisphosphate carboxylase/oxygenase activity in Chlorella cells, suggesting that this compound can directly suppress the photosynthetic Calvin cycle. When cells were subsequently exposed to light, the disruption of this cycle resulted in an excess of excitation energy, in turn driving the excessive generation of reactive oxygen species (ROS). ROS-mediated disruption of cellular metabolism further aggravated this ONT-induced microalgal damage. As such, under natural light conditions, these microalgae cells are exposed to increased oxidative stress that impairs their growth and causes pigment bleaching. Restricting the utilization of ONT-containing sunscreens thus has the potential to better preserve the integrity of aquatic and terrestrial ecosystems.

DNA methylation of GFI1 as a mediator of the association between prenatal smoking exposure and ADHD symptoms at 6 years: the Hokkaido Study on Environment and Children's Health

BACKGROUND

Prenatal smoking exposure has been associated with childhood attention-deficit/hyperactivity disorder (ADHD). However, the mechanism underlying this relationship remains unclear. We assessed whether DNA methylation differences may mediate the association between prenatal smoking exposure and ADHD symptoms at the age of 6 years.

RESULTS

We selected 1150 mother-infant pairs from the Hokkaido Study on the Environment and Children's Health. Mothers were categorized into three groups according to plasma cotinine levels at the third trimester: non-smokers (≤ 0.21 ng/mL), passive smokers (0.21-11.48 ng/mL), and active smokers (≥ 11.49 ng/mL). The children's ADHD symptoms were determined by the ADHD-Rating Scale at the age of 6 years. Maternal active smoking during pregnancy was significantly associated with an increased risk of ADHD symptoms (odds ratio, 1.89; 95% confidence interval, 1.14-3.15) compared to non-smoking after adjusting for covariates. DNA methylation of the growth factor-independent 1 transcriptional repressor (GFI1) region, as determined by bisulfite next-generation sequencing of cord blood samples, mediated 48.4% of the total effect of the association between maternal active smoking during pregnancy and ADHD symptoms. DNA methylation patterns of other genes (aryl-hydrocarbon receptor repressor [AHRR], cytochrome P450 family 1 subfamily A member 1 [CYP1A1], estrogen receptor 1 [ESR1], and myosin IG [MYO1G]) regions did not exert a statistically significant mediation effect.

CONCLUSIONS

Our findings demonstrated that DNA methylation of GFI1 mediated the association between maternal active smoking during pregnancy and ADHD symptoms at the age of 6 years.

Influence of progestational stress on BDNF and NMDARs in the hippocampus of male offspring and amelioration by Chaihu Shugan San

BACKGROUND

Progestational stress has been proven to be a risk for the neural development of offspring, especially in the hippocampus. However, whether Chaihu Shugan San (CSS) can ameliorate hippocampal neural development via the regulation of brain-derived neurotrophic factor (BDNF), and N-methyl-D-aspartate receptors (NMDAR) 2A (NR2A) and 2B (NR2B), and the mechanism of such action remains unclear.

METHODS

Thirty-six female rats were randomly allocated into control, chronic immobilization stress (CIS) and CSS groups according to the random number table, respectively. The male offspring were fed for 21 days after birth then randomly divided into the same three groups (6 rats/group) as the female rats. Female rats, except for the control group, underwent 21-day CIS to established a progestational stress anxiety-like model which was evaluated by body weight, the elevated plus-maze (EPM) test and serum dopamine (DA) measured using an enzyme-linked immunosorbent assay (ELISA). The expression levels of estrogen receptors (ERα/ERβ) and progesterone receptor (PR) in female rat ovaries were quantified by real-time fluorescence quantitative polymerase chain reaction (RT-qPCR) and Western blot analysis. The hippocampal tissue in the 21-day offspring was observed by hematoxylin-eosin (HE) staining. The concentration of BDNF, NR2A, and NR2B were measured by RT-qPCR and immunohistochemistry in the CA3 and dentate gyrus (DG) regions of offsprings' hippocampus.

RESULTS

Compared with the female control group, significant differences in body weight, EPM test and DA concentration were observed in the CIS group, meanwhile, the concentration of ERα (P < 0.05), PR (P < 0.05) and ERβ in the ovaries were decreased. In the offsprings' hippocampus of the CIS group, the chromatin of the nucleus was edge set and with condensed and irregular morphology nucleus, and the cytoplasm was unevenly stained with spaces around the cells, moreover, the expression levels of BDNF, NR2A, and NR2B were also declined (P < 0.05). However, Chaihu Shugan San reversed these changes, especially the BDNF in the DG region (P < 0.05), and NR2A and NR2B in the CA3 and DG region (P < 0.05).

CONCLUSIONS

CSS could ameliorate the neural development of the hippocampus in offspring damaged by anxiety-like progestational stress in female rats via regulating the expression levels of ERα, ERβ, and PR in female rat ovaries and BDNF, NR2A, and NR2B in the hippocampus of their offspring.

Toxicology and carcinogenesis studies of 2-hydroxy-4-methoxybenzophenone administered in feed to Sprague Dawley (Hsd:Sprague Dawley SD) rats and B6C3F1/N mice

2-Hydroxy-4-methoxybenzophenone (2H4MBP) is approved by the U.S. Food and Drug Administration for use in sunscreens and other personal products in concentrations of up to 6% either alone or in combination formulations and as an indirect food additive in acrylic and modified acrylic plastics that come into contact with food. 2H4MBP was nominated to the National Toxicology Program by the National Cancer Institute due to widespread exposure via sunscreen use and lack of carcinogenicity data. 2H4MBP was also nominated by a private individual to ascertain genotoxic potential. Male and female Sprague Dawley (Hsd:Sprague Dawley SD) rats (after weaning) and B6C3F1/N mice were exposed to 2H4MBP (greater than 99% pure) in feed for 2 years. Perinatal studies and 14-week interim evaluations were also conducted in rats. Genetic toxicology studies were conducted in Salmonella typhimurium and Escherichia coli. (Abstract Abridged).

Benzophenone-3 degradation via UV/H2O2 and UV/persulfate reactions

The degradation of benzophenone-3 (BP3) in water via the UV/H₂O₂ and UV/persulfate (UV/PS) reactions was investigated. The degradation of BP3 exhibited pseudo-first-order kinetics in both reactions. The degradation efficiency of BP3 was higher in the UV/PS reaction than in the UV/H₂O₂ reaction. In both reactions, the observed rate constants (k_obs) of BP3 degradation were highest at pH 6 and increased linearly with increasing dosage of H₂O₂ and persulfate. The second-order rate constants of BP3 with •OH (k_{•OH_BP3}) and •SO₄^- (k_•SO4-_{_BP3}) were determined to be 1.09 (± 0.05) × 10¹⁰ and 1.67 (± 0.04) × 10⁹ M^-1 s^-1, respectively. The k_obs values of BP3 were affected by water components such as HCO₃^-, NO₃^-, Cl^-, and Br^- ions, as well as humic acid. Based on the identified transformation products (TPs), the degradation pathway of BP3 during both reactions was a hydroxylation reaction. The inhibition of bioluminescence in Vibrio fischeri due to BP3 and its TPs decreased more quickly in the UV/PS reaction than in the UV/H₂O₂ reaction. The results suggest that the UV/PS process is a better alternative to the UV/H₂O₂ process for removing BP3 and its toxicity in water.

Effects of Nanoplastics and Butyl Methoxydibenzoylmethane on Early Zebrafish Embryos Identified by Single-Cell RNA Sequencing

Nanoplastics with small particle sizes and high surface area/volume ratios easily absorb environmental pollutants and affect their bioavailability. In this study, polystyrene nanoplastic beads (PS-NPBs) with a particle size of 100 nm and butyl methoxydibenzoylmethane (BMDBM) sunscreen in personal-care products were chosen as target pollutants to study their developmental toxicity and interactive effects on zebrafish embryos. The exposure period was set from 2 to 12 h postfertilization (hpf). BMDBM and PS-NPBs significantly upregulated genes related to antioxidant enzymes and downregulated the gene expression of aromatase and DNA methyltransferases, but the influenced genes were not exactly the same. The combined exposure reduced the adverse effects on the expression of all genes. With the help of the single-cell RNA sequencing technology, neural mid cells were identified as the target cells of both pollutants, and brain development, head development, and the notch signaling pathway were the functions they commonly altered. The key genes and functions that are specifically affected by BMDBM and/or PS-NPBs were identified. BMDBM mainly affects the differentiation and fate of neurons in the central nervous system through the regulation of her5, her6, her11, lfng, pax2a, and fgfr4. The PS-NPBs regulate the expression of olig2, foxg1a, fzd8b, six3a, rx1, lhx2b, nkx2.1a, and sfrp5 to alter nervous system development, retinal development, and stem cell differentiation. The phenotypic responses of zebrafish larvae at 120 hpf were tested, and significant inhibition of locomotor activity was found, indicating that early effects on the central nervous system would have a sustained impact on the behavior of zebrafish.

Maternal and childhood urinary phenol concentrations, neonatal thyroid function, and behavioral problems at 10 years of age: The SMBCS study

BACKGROUND

Environmental phenols, bisphenol A (BPA), triclosan (TCS), and benzophenone-3 (BP-3), are known as emerging endocrine-disrupting chemicals; however, their impacts on thyroid hormones and children's neurobehaviors are still unclear.

OBJECTIVES

We aimed to examine the associations of prenatal and childhood exposure to phenols with neonatal thyroid function and childhood behavioral problems aged 10 years.

METHODS

A total of 386 mother-singleton pairs were included from Sheyang Mini Birth Cohort Study (SMBCS), a longitudinal birth cohort in China. We quantified urinary BPA, TCS and BP-3 concentrations in maternal and 10-year-old children's urine samples using gas chromatography tandem mass spectrometry and thyroid function parameters in cord serum samples. Caregivers completed the Strength and Difficulties Questionnaire (SDQ) for their children at 10 years of age. Multivariable linear regression models and logistic regression models were applied to estimate associations of urinary phenol concentrations with thyroid hormones and risks of children's behavioral problems, respectively.

RESULTS

The median values of urinary BPA, TCS and BP-3 concentrations for pregnant women were 1.75 μg/L, 0.54 μg/L and 0.37 μg/L, while 1.29 μg/L, 6.64 μg/L and 1.39 μg/L for children, respectively. Maternal urinary BPA concentrations were in associations with 1.00% [95% confidence interval (CI): 0.20%, 1.92%] increases in cord serum FT4 concentrations and significantly associated with increased risks of total difficulties [odds ratio (OR): 1.45, 95% CI: 1.07, 1.97], while maternal urinary levels of BP-3 were significantly related to poorer prosocial behaviors (OR: 1.58, 95% CI: 1.04, 2.39) of children at 10 years of age. In sex-stratified analyses, maternal urinary BPA concentrations were related to increased total difficulty subscales only in boys.

CONCLUSIONS

The findings indicated that higher prenatal urinary BPA concentrations were associated with increased risks of total difficulties, especially in boys and maternal urinary BP-3 concentrations were related to poorer prosocial behaviors at 10 years.

Autophagy-related neurotoxicity is mediated via AHR and CAR in mouse neurons exposed to DDE

DDE (dichlorodiphenyldichloroethylene) is an environmental metabolite of the pesticide DDT, which is still present in the environment, and its insecticidal properties are used to fight malaria and the Zika virus disease. We showed for the first time that the neurotoxic effects of DDE involve autophagy, as demonstrated by elevated levels of Becn1, Map1lc3a/MAP1LC3A, Map1lc3b, and Nup62/NUP62 and an increase in autophagosome formation. The suggestion that the aryl hydrocarbon receptor (AHR) and the constitutive androstane receptor (CAR) are involved in the neurotoxic effect of DDE was supported by increases in the mRNA and protein expression of these receptors, as detected by qPCR, ELISA, immunofluorescence labeling and confocal microscopy. Selective antagonists of the receptors, including alpha-naphthoflavone, CH223191, and CINPA 1, inhibited p,p'-DDE- and o,p'-DDE-induced LDH release and caspase-3 activity, while specific siRNAs (Ahr and Car siRNA) reduced the levels of p,p'-DDE- and o,p'-DDE-induced autophagosome formation. Although the neurotoxic effects of DDE were isomer independent, the mechanisms of p,p'- and o,p'-DDE were isomer specific. Therefore, we identified previously unknown mechanisms of the neurotoxic actions of DDE that, in addition to inducing apoptosis, stimulate autophagy in mouse neocortical cultures and induce AHR and CAR signaling.

Selective Targeting of Non-nuclear Estrogen Receptors with PaPE-1 as a New Treatment Strategy for Alzheimer's Disease

Alzheimer’s disease (AD) is a multifactorial and severe neurodegenerative disorder characterized by progressive memory decline, the presence of Aβ plaques and tau tangles, brain atrophy, and neuronal loss. Available therapies provide moderate symptomatic relief but do not alter disease progression. This study demonstrated that PaPE-1, which has been designed to selectively activate non-nuclear estrogen receptors (ERs), has anti-AD capacity, as evidenced in a cellular model of the disease. In this model, the treatment of mouse neocortical neurons with Aβ (5 and 10 μM) induced apoptosis (loss of mitochondrial membrane potential, activation of caspase-3, induction of apoptosis-related genes and proteins) accompanied by increases in levels of reactive oxygen species (ROS) and lactate dehydrogenase (LDH) as well as reduced cell viability. Following 24 h of exposure, PaPE-1 inhibited Aβ-evoked effects, as shown by reduced parameters of neurotoxicity, oxidative stress, and apoptosis. Because PaPE-1 downregulated Aβ-induced Fas/FAS expression but upregulated that of Aβ-induced FasL, the role of PaPE-1 in controlling the external apoptotic pathway is controversial. However, PaPE-1 normalized Aβ-induced loss of mitochondrial membrane potential and restored the BAX/BCL2 ratio, suggesting that the anti-AD capacity of PaPE-1 particularly relies on inhibition of the mitochondrial apoptotic pathway. These data provide new evidence for an anti-AD strategy that utilizes the selective targeting of non-nuclear ERs with PaPE-1.

Environmental relevant concentrations of benzophenone-3 induced developmental neurotoxicity in zebrafish

Benzophenone-3 (BP3 or oxybenzone) is an organic UV filter that has been widely used in personal care products. Its frequent detection in the environment and humans as well as its structural similarity to estradiol have prompted most research focus on its endocrine effect. However, these effects are usually associated with concentrations 10-100 fold higher than its environmental relevant concentrations. Few studies explore its adverse effects at environmental relevant concentrations. In the present study, we evaluated the developmental neurotoxic (DNT) effects of low concentration BP3 exposure during a sensitive developmental window in zebrafish. Our findings revealed that BP3 exposure at 10 μg/L (0.04 μM) during 6-24 h post fertilization (hpf) led to various DNT effects such as increased spontaneous movement at 21 and 24 hpf, decreased touch response at 27 hpf, heightened hyperactivity in locomotor response at 5 day post fertilization (dpf), decreased shoaling behavior at 11 dpf and decreased mirror attacks at 12 dpf. These effects were accompanied with decreased axonal growth at 27 hpf, decreased cell proliferation and increased cell apoptosis in the head region of larval zebrafish immediately after BP3 exposure at 24 hpf, and increased expression of retinoid X receptor gene rxrgb at 5 dpf. Interestingly, rxrgb knockdown through morpholino injection largely restored most of BP3-induced DNT effects, axonal growth delay, cell proliferation and cell apoptosis, suggesting that BP3-induced DNT effects are likely mediated through the Rxrgb receptor. In considering with recent findings on the endocrine effects of BP3, we conclude that BP3 at environmental relevant concentrations has limited estrogenic effect, but is neurotoxic to developing embryos in zebrafish.

The neuroprotective action of 3,3'-diindolylmethane against ischemia involves an inhibition of apoptosis and autophagy that depends on HDAC and AhR/CYP1A1 but not ERα/CYP19A1 signaling

There are no studies examining the effects of 3,3′-diindolylmethane (DIM) in neuronal cells subjected to ischemia. Little is also known about the roles of apoptosis and autophagy as well as AhR and ERα signaling and HDACs in DIM action. We demonstrated for the first time the strong neuroprotective capacity of DIM in mouse primary hippocampal cell cultures exposed to ischemia at early and later stages of neuronal development. The protective effects of DIM were mediated via inhibition of ischemia-induced apoptosis and autophagy that was accompanied by a decrease in AhR/CYP1A1 signaling and an increase in HDAC activity. DIM decreased the levels of pro-apoptotic factors, i.e., Fas, Caspase-3, and p38 mitogen-activated protein kinase (MAPK). DIM also reduced the protein levels of autophagy-related Beclin-1 (BECN1) and microtubule-associated proteins 1A/1B light chain (LC3), partially reversed the ischemia-induced decrease in Nucleoporin 62 (NUP62) and inhibited autophagosome formation. In addition, DIM completely reversed the ischemia-induced decrease in histone deacetylase (HDAC) activity in hippocampal neurons. Although DIM inhibited AhR/CYP1A1 signaling, it did not influence the protein expression levels of ERα and ERα-regulated CYP19A1 which are known to be controlled by AhR. This study demonstrated for the first time, that the neuroprotective action of 3,3′-diindolylmethane against ischemia involves an inhibition of apoptosis and autophagy and depends on AhR/CYP1A1 signaling and HDAC activity, thus creating the possibility of developing new therapeutic strategies that target neuronal degeneration at specific molecular levels.

Comparison of toxicological effects of oxybenzone, avobenzone, octocrylene, and octinoxate sunscreen ingredients on cucumber plants (Cucumis sativus L.)

Oxybenzone (OBZ), avobenzone (AVB), octocrylene (OCR) and octinoxate (OMC) are ultraviolet (UV) filters commonly added to chemical sunscreens. These UV filters are known to widely contaminate the environment through a variety of anthropogenic sources, including sewage discharge. However, systematic studies of the damage caused by these four UV filters and their toxicopathological differences in a variety of plant species are lacking. In this study, we demonstrated that irrigation with water containing these four UV filters could significantly inhibit the aboveground growth of cucumber plant. All of the UV filters decreased photosynthesis through nonstomatal factors but via different inhibitory mechanisms. Only OBZ inhibited photosynthesis by directly inhibiting photosynthetic electron transport, while the other three (AVB, OCR, and OMC) inhibited photosynthesis by inhibiting the Calvin-Benson cycle. Additionally, these four UV filters also decreased plant respiration under long-term treatment. Photosynthesis and respiration inhibition led to the over production of reactive oxygen species (ROS) and the formation of lipid peroxidation damage products, which further damaged the structure and function of plant cells, causing secondary pathologies and potentially leading to reduced crop yields. The study also demonstrated that these four UV filters caused different degrees of phototoxic damage to cucumber plants. On the basis of comprehensive evaluation, we speculated that the order of the four UV filters in terms of plant damage was OBZ > AVB > OMC > OCR. Because of the severe damaging effects of these UV filters on plant growth, the application of contaminated biosolids/reclaimed water in agriculture reduces agricultural production and may damage ecosystems. The results of this study can advance recognition of the hazards associated with environmental and agricultural pollution via UV filters and encourage consumers and the industry to limit or reduce the application of cosmetics and over-the-counter drugs containing these substances.

Effect of Combined Prenatal and Adult Benzophenone-3 Dermal Exposure on Factors Regulating Neurodegenerative Processes, Blood Hormone Levels, and Hematological Parameters in Female Rats

Benzophenone-3 (BP-3), the most widely used UV chemical filter, is absorbed well through the skin and gastrointestinal tract and can affect some body functions, including the survival of nerve cells. Previously, we showed that BP-3 evoked a neurotoxic effect in male rats, but since the effects of this compound are known to depend on gender, the aim of the present study was to show the concentration and potential neurotoxic action of this compound in the female rat brain. BP-3 was administered dermally to female rats during pregnancy, and then in the 7th and 8th weeks of age to their female offspring. The effect of BP-3 exposure on short-term and spatial memory, its concentrations in blood, the liver, the frontal cortex, and the hippocampus, and the effect on selected markers of brain damage were determined. Also, the impact of BP-3 on sex and thyroid hormone levels in blood and hematological parameters was examined. It has been found that this compound was present in blood and brain structures in females at a lower concentration than in males. BP-3 in both examined brain structures increased extracellular glutamate concentration and enhanced lipid peroxidation, but did not induce the apoptotic process. The tested compound also evoked hyperthyroidism and decreased the blood progesterone level and the number of erythrocytes. The presented data indicated that, after the same exposure to BP-3, this compound was at a lower concentration in the female brain than in that of the males. Although BP-3 did not induce apoptosis in the hippocampus and frontal cortex, the increased extracellular glutamate concentration and lipid peroxidation, as well as impaired spatial memory, suggested that this compound also had adverse effects in the female brain yet was weaker than in males. In contrast to the weaker effects of the BP-3 on females than the brain of males, this compound affected the endocrine system and evoked a disturbance in hematological parameters more strongly than in male rats.

Protocol for DNA Microarrays on Glass Slides

The DNA microarray is a powerful, flexible, nonbiased discovery technology. Microarrays can be used to assess processes from gene expression to long noncoding RNAs to specific pathologies, as well as many others. This chapter describes the protocol for DNA microarray analysis of differential gene expression using DNA sequences spotted on microscope slides.

Triclocarban impairs autophagy in neuronal cells and disrupts estrogen receptor signaling via hypermethylation of specific genes

Although an increasing body of evidence suggests that triclocarban, a phenyl ether classified as a contaminant of emerging concern, presents a risk to development, there is limited data available on the potential interplay of triclocarban with the developing mammalian nervous system. This study was aimed to investigate the impact of environmentally pervasive chemical triclocarban on autophagy and estrogen receptor-mediated signaling pathways in mouse neurons. The study showed that triclocarban impaired autophagy and disrupted estrogen receptor signaling in mouse embryonic neurons in primary culture. Triclocarban used at environmentally relevant concentrations inhibited the mRNA and protein expression of ESR1 and GPER1 but not ESR2. The triclocarban-induced decrease in the expression of estrogen receptors was supported by the colocalization of the receptors in mouse neurons and corresponded to hypermethylation of the Esr1 and Gper1 genes. Selective antagonists increased the effects of triclocarban, which suggests that the neurotoxic effects of triclocarban, in addition to decreasing estrogen receptor expression, are mediated via inhibition of the neuroprotective capacity of the receptors. Furthermore, Becn1 and Atg7 siRNAs potentiated the caspase-3-dependent effect of triclocarban, which points to triclocarban-induced impairment of autophagy. Indeed, triclocarban dysregulated the expression of autophagy-related genes, and caused a time-dependent inhibition of the mRNA expression of Becn1, Map1lc3a, Map1lc3b, Nup62, and Atg7, which was correlated with a decrease in the protein levels of MAP1LC3B, BECN1 and autophagosomes, but not NUP62 protein level which was increased. Intriguingly, the Esr1 and Gper1 siRNAs did not affect the level of autophagosomes, suggesting that the triclocarban-induced impairment of autophagy is independent of the triclocarban-induced disruption of estrogen receptor signaling in mammalian neurons. Because our data provided evidence that triclocarban has the capacity to impair autophagy and disrupt estrogen receptor signaling in brain neurons at an early developmental stage, we postulate to categorize the compound as a neurodevelopmental risk factor.

Murine maternal dietary restriction affects neural Humanin expression and cellular profile

To understand the cellular basis for the neurodevelopmental effects of intrauterine growth restriction (IUGR), we examined the global and regional expression of various cell types within murine (Mus musculus) fetal brain. Our model employed maternal calorie restriction to 50% daily food intake from gestation day 10-19, producing IUGR offspring. Offspring had smaller head sizes with larger head:body ratios indicating a head sparing IUGR effect. IUGR fetuses at embryonic day 19 (E19) had reduced nestin (progenitors), β-III tubulin (immature neurons), Glial fibrillary acidic protein (astrocytes), and O4 (oligodendrocytes) cell lineages via immunofluorescence quantification and a 30% reduction in cortical thickness. No difference was found in Bcl-2 or Bax (apoptosis) between controls and IUGR, though qualitatively, immunoreactivity of doublecortin (migration) and Ki67 (proliferation) was decreased. In the interest of examining a potential therapeutic peptide, we next investigated a novel pro-survival peptide, mouse Humanin (mHN). Ontogeny examination revealed highest mHN expression at E19, diminishing by postnatal day 15 (P15), and nearly absent in adult (3 months). Subanalysis by sex at E19 yielded higher mHN expression among males during fetal life, without significant difference between sexes postnatally. Furthermore, female IUGR mice at E19 had a greater increase in cortical mHN versus the male fetus over their respective controls. We conclude that maternal dietary restriction-associated IUGR interferes with neural progenitors differentiating into the various cellular components populating the cerebral cortex, and reduces cerebral cortical size. mHN expression is developmental stage and sex specific, with IUGR, particularly in the females, adaptively increasing its expression toward mediating a pro-survival approach against nutritional adversity.

Glutathione Deficiency and Alterations in the Sulfur Amino Acid Homeostasis during Early Postnatal Development as Potential Triggering Factors for Schizophrenia-Like Behavior in Adult Rats

Impaired glutathione (GSH) synthesis and dopaminergic transmission are important factors in the pathophysiology of schizophrenia. Our research aimed to assess the effects of l-buthionine-(S,R)-sulfoximine (BSO), a GSH synthesis inhibitor, and GBR 12909, a dopamine reuptake inhibitor, administered alone or in combination, to Sprague–Dawley rats during early postnatal development (p5–p16), on the levels of GSH, sulfur amino acids, global DNA methylation, and schizophrenia-like behavior. GSH, methionine (Met), homocysteine (Hcy), and cysteine (Cys) contents were determined in the liver, kidney, and in the prefrontal cortex (PFC) and hippocampus (HIP) of 16-day-old rats. DNA methylation in the PFC and HIP and schizophrenia-like behavior were assessed in adulthood (p90–p93). BSO caused the tissue-dependent decreases in GSH content and alterations in Met, Hcy, and Cys levels in the peripheral tissues and in the PFC and HIP. The changes in these parameters were accompanied by alterations in the global DNA methylation in the studied brain structures. Parallel to changes in the global DNA methylation, deficits in the social behaviors and cognitive functions were observed in adulthood. Only BSO + GBR 12909-treated rats exhibited behavioral alterations resembling positive symptoms in schizophrenia patients. Our results suggest the usefulness of this neurodevelopmental model for research on the pathomechanism of schizophrenia.

Benzophenone-2 Concentration and Its Effect on Oxidative Stress and Apoptosis Markers in Rat Brain

Benzophenones, frequently used as UV chemical filters, are absorbed through the skin and can exert systemic adverse effects. So far, most of the data are related to their action on sex hormone receptors whereas potential neurotoxic effect is expected mainly on the basis of in vitro studies. The aim of the present study was to determine concentrations of BP-2, oxidative stress and apoptosis markers in the rat brain after topical administration of this compound. Male Wistar rats were treated dermally with BP-2 (100 mg/kg, 4 weeks), and next, blood and tissue BP-2 concentrations and oxidative stress and apoptotic markers in the frontal cortex and hippocampus were determined. After dermal BP-2 administration, blood level of this compound was about 300 ng/ml while in the liver and adipose tissue 1354 and 823 ng/g wt tissue, respectively. In the studied brain structures, the levels of the test compound were from 5 to 19 ng/g tissue. In the hippocampus, where BP-2 level was about 3.5-fold lower than in the frontal cortex, no significant changes in either oxidative stress and apoptosis markers were observed. There was also no change in apoptosis markers in the frontal cortex but unexpectedly the oxidative stress markers were reduced. The research showed that BP-2 passes through the blood-brain barrier but its concentration in the brain structures are much lower than in the blood. This compound did not exacerbate oxidative stress and apoptosis markers in the hippocampus and frontal cortex, and even lowered oxidative stress in the frontal cortex.

Can oxybenzone cause Hirschsprung's disease?

Oxybenzone is a ultraviolet (UV) absorber used in 70% of sunscreen products, is a recognized endocrine disrupting chemical (EDC) and is small enough to pass through skin and placenta barriers. Numerous studies have identified this chemical in the urine/blood of pregnant women as well as in fetal and umbilical cord blood. A recent study demonstrated that women with medium to high levels of oxybenzone in their urine was associated with giving birth to neonates with Hirschsprung's Disease (HSCR). Testing in human cell lines confirmed that low levels of oxybenzone has the potential to disrupt cell migration and function in a manner similar to what is associated with HSCR. Analysis of human exposure levels to oxybenzone from sunscreen use, under normal conditions, demonstrates that enough chemical can cross into the mother's blood making it available to the fetus at high enough levels that can indeed inhibit migration of neural crest cells during critical embryonic development.

Environmentally Induced Epigenetic Plasticity in Development: Epigenetic Toxicity and Epigenetic Adaptation

PURPOSE OF REVIEW

Epigenetic processes represent important mechanisms underlying developmental plasticity in response to environmental exposures. The current review discusses three classes of environmentally-induced epigenetic changes reflecting two aspects of that plasticity, toxicity effects as well as adaptation in the process of development.

RECENT FINDINGS

Due to innate resilience, epigenetic changes caused by environmental exposures may not always lead impairments but may allow the organisms to achieve positive developmental outcomes through appropriate adaptation and a buffering response. Thus, some epigenetic adaptive responses to an immediate stimulus or exposure early in life would be expected to have a survival advantage but these same responses may also result in adverse developmental outcomes as they persists into later life stage. Although accumulating literature has identified environmentally induced epigenetic changes and linked them to health outcomes, we currently face challenges in the interpretation of the functional impact of their epigenetic plasticity.

SUMMARY

Current environmental epigenetic research suggest that epigenetic processes may serve as a mechanism for resilience, and that they can be considered in terms of their impact on toxicity as a negative outcome, but also on adaptation for improved survival or health. This review encourages epigenetic environmental studies to move deeper inside into the functional meaning of epigenetic plasticity in the development.

Prenatal Exposure to Benzophenone-3 Impairs Autophagy, Disrupts RXRs/PPARγ Signaling, and Alters Epigenetic and Post-Translational Statuses in Brain Neurons

The UV absorber benzophenone-3 (BP-3) is the most extensively used chemical substance in various personal care products. Despite that BP-3 exposure is widespread, knowledge about the impact of BP-3 on the brain development is negligible. The present study aimed to explore the mechanisms of prenatal exposure to BP-3 in neuronal cells, with particular emphasis on autophagy and nuclear receptors signaling as well as the epigenetic and post-translational modifications occurring in response to BP-3. To observe the impact of prenatal exposure to BP-3, we administered BP-3 to pregnant mice, and next, we isolated brain tissue from pretreated embryos for primary cell neocortical culture. Our study revealed that prenatal exposure to BP-3 (used in environmentally relevant doses) impairs autophagy in terms of BECLIN-1, MAP1LC3B, autophagosomes, and autophagy-related factors; disrupts the levels of retinoid X receptors (RXRs) and peroxisome proliferator-activated receptor gamma (PPARγ); alters epigenetic status (i.e., attenuates HDAC and sirtuin activities); inhibits post-translational modifications in terms of global sumoylation; and dysregulates expression of neurogenesis- and neurotransmitter-related genes as well as miRNAs involved in pathologies of the nervous system. Our study also showed that BP-3 has good permeability through the BBB. We strongly suggest that BP-3-evoked effects may substantiate a fetal basis of the adult onset of neurological diseases, particularly schizophrenia and Alzheimer’s disease.

Triclocarban Disrupts the Epigenetic Status of Neuronal Cells and Induces AHR/CAR-Mediated Apoptosis

Triclocarban is a phenyl ether that has recently been classified as a contaminant of emerging concern. Evidence shows that triclocarban is present in human tissues, but little is known about the impact of triclocarban on the nervous system, particularly at early developmental stages. This study demonstrated that triclocarban that was used at environmentally relevant concentrations induced apoptosis in mouse embryonic neurons, inhibited sumoylation, and changed the epigenetic status, as evidenced by impaired activities of HDAC, sirtuins, and DNMT, global DNA hypomethylation, and alterations of methylation levels of bax, bcl2, Ahr, and Car genes. The use of selective antagonists and specific siRNAs, which was followed by the co-localization of aryl hydrocarbon receptor (AHR) and constitutive androstane receptor (CAR) in mouse neurons, points to the involvement of AHR and CAR in triclocarban-induced neurotoxicity. A 24-h treatment with triclocarban enhanced protein levels of the receptors which was paralleled by Car hypomethylation and Ahr hypermethylation. Car hypomethylation is in line with global DNA hypomethylation and explains the increased mRNA and protein levels of CAR in response to triclocarban. Ahr hypermethylation could reflect reduced Ahr mRNA expression and corresponds to lowered protein levels after 3- and 6-h exposures to triclocarban that is likely related to proteasomal degradation of activated AHR. We hypothesize that the triclocarban-induced apoptosis in mouse neurons and the disruption of epigenetic status involve both AHR- and CAR-mediated effects, which may substantiate a fetal basis of the adult onset of neurological diseases; however, the expression of the receptors is regulated in different ways.