An updated systematic review on the possible effect of nonylphenol on male fertility

Gender difference and BMDL exploration of developmental immunotoxicity induced by early-life low-dose exposure to 4-nonylphenol in Wistar rats

BACKGROUND

Nonylphenol (NP) is a widespread environmental endocrine disruptor with potential developmental immunotoxicity. The present study aimed to investigate the gender-specific developmental immunotoxic effects of early-life exposure to low doses of 4-nonylphenol (4-NP) on Wistar rats and the corresponding thresholds.

METHODS

Pregnant rats (F0 generation) were exposed to low doses of 4-NP from gestational day 6 (GD6) to postnatal day 90 (PND90), and F1 offspring continued to be exposed until the maturation of the immune system on PND42. We assessed immune organ development, immune responses, lymphocyte subset composition, cytokine secretion, and the Th17/Treg cell balance as endpoints for developmental immunotoxicity. Benchmark Dose analysis was conducted to explore the thresholds.

RESULTS

Early-life exposure to 4-NP led to significant gender-specific differences in the immune response. Female pups exhibited greater sensitivity to 4-NP, with reduced thymus and spleen weights, suppressed humoral immune function, decreased natural killer (NK) cell activity, and an imbalance in the Th17/Treg cell ratio. Male pups showed inhibition of NK cell activity but no significant changes in humoral immune function. Levels of phosphorylated STAT3, STAT5, and JAK3 proteins increased in the spleens of exposed pups of both gender. The lowest benchmark dose lower limit (BMDL) value of developmental immunotoxicity was lower in female rats (based on the thymus weight) than in male rats (based on the NK cell activity).

CONCLUSION

Early-life exposure to 4-NP has been shown to induce gender-specific developmental immunotoxicity in rats, with female pups exhibiting greater sensitivity. And developmental immunotoxicity may serve as a more sensitive indicator for the risk assessment of 4-NP. Th17/Treg balance may be interrupted through JNK/STAT pathway by 4-NP exposure, which needs to be further investigated.

Bisphenol F (BPF) exposure impairs sperm quality and offspring development in male zebrafish

BACKGROUND

Bisphenol F (BPF), a substitute for bisphenol A (BPA), is widely used in consumer products, increasing the potential for environmental exposure. Our study investigated the reproductive effects of BPF on adult male zebrafish and explored its toxicological mechanisms, as well as its intergenerational effects.

METHODS

Adult male zebrafish were exposed to BPF concentrations of 0, 50, 500, 2500, and 5000 nM for 21 days. We evaluated sperm cell quantity and quality, hormonal markers testosterone (T) and vitellogenin (VTG), gene expression profiles related to hormone synthesis, metabolism, apoptosis, cell cycle, sexual behavior, and offspring health metrics including survival, development and locomotion.

RESULTS

BPF exposure did not significantly affect body weight or gonadal index. However, at 500 and 2500 nM, a significant reduction in sperm count was observed. BPF exposure led to decreased serum T and increased hepatic VTG levels, indicating hormonal disruption. At 50 nM, BPF initiated sperm apoptosis, and at higher doses, it disrupted sperm meiosis, affecting cell distribution. This exposure negatively impacted sperm quality, reduced offspring survival rates, and altered sperm motility in adult fish. Offspring from BPF-exposed groups showed developmental issues, including increased mortality, delayed developmental stages, abnormal tail coiling and heart rate, which correlated with paternal sperm count and quality changes, alterations in T and VTG levels, and cell cycle phase distributions.

CONCLUSIONS

Our study demonstrated that BPF exposure significantly impacted sperm quality, characterized by reduced sperm count and altered motility patterns, leading to developmental anomalies in offspring. These novel findings highlight the need for further research into BPF's reproductive and developmental toxicity, emphasizing the potential risks to aquatic ecosystems and human health. The observed effects on sperm quality, hormonal balance, and offspring development provide new insights into the reproductive toxicity profile of BPF.

Assessment of nonylphenol exposure based on global urinary concentration data and its risk analysis

Nonylphenol (NP) has been recognized as a priority hazardous substance because of its estrogenic activity and ubiquity in the environment. Therefore, it is important to understand the daily intake of NP in humans and evaluate the potential health risks of NP. The median or average estimated daily intake (EDI) of NP was estimated based on urinary NP or alkyl-chain-oxidized NP metabolites concentration data from published epidemiological studies. In brief, we acquired 34 peer-reviewed publications, which contained 14235 samples from twelve countries or regions. The global average estimated daily intake of NP was 1.003 μg/(kg bw·day), which was lower than the tolerable daily intake recommended by the Danish Veterinary and Food Authority [5 μg/(kg bw·day)]. Korea had the highest exposure level [3.471 μg/(kg bw·day)] among different countries or regions. Compared with the adult [0.743 μg/(kg bw·day)] and pregnant women [0.806 μg/(kg bw·day)] groups, the children group had the highest estimated daily intake of NP at 2.368 μg/(kg bw·day). Besides, the global NP risk hazard quotient was 0.201, and the risk hazard quotients of all countries or regions were less than 1. However, the global HQ value of the 95th quantile population was 2.299, which was much higher than 1, the potential health risk cannot be ignored and needs to be confirmed by more research. To our knowledge, this is the first study to assess the overall NP exposure levels based on published biomonitoring data, and has important implications for assessing the potential effects of NP exposure on human health. In addition, OH-NP is a robust and sensitive novel biomarker for NP, there are fewer studies on the application of this biomarker, and more studies are needed in the future for quantitative exposure and risk assessment of NP.

Nonylphenol and its derivatives: Environmental distribution, treatment strategy, management and future perspectives

In recent years, emerging pollutants, including nonylphenol (NP) and nonylphenol ethoxylate (NPE), have become a prominent topic. These substances are also classified as persistent organic pollutants. NP significantly affects the hormone secretion of organisms and exhibits neurotoxicity, which can affect the human hippocampus. Therefore, various countries are paying increased attention to NP regulation. NPEs are precursors of NPs and are widely used in the manufacture of various detergents and lubricants. NPEs can easily decompose into NPs, which possess strong biological and environmental toxicity. This review primarily addresses the distribution, toxicity mechanisms and performance, degradation technologies, management policies, and green alternative reagents of NPs and NPEs. Traditional treatment measures have been unable to completely remove NP from wastewater. With the progressively tightening management and regulatory policies, identifying proficient and convenient treatment methods and a sustainable substitute reagent with comparable product effectiveness is crucial.

Relationship between Eating Habits and 4-Nonylphenol Concentration in Breast Milk of Women in Slovakia

4-Nonylphenol belongs to the alkylphenol group of chemicals, and its high occurrence in the environment can cause an adverse effect on human health. Breast milk can serve as a marker to take measure of human exposure to these chemicals through different routes of exposure. In this work, the influence of selected factors (the kind of water drank by the mothers; the consumption of fish, pork, and beef; wearing gloves; using nail polish, gel nails, vitamins, and medication) on the concentration on 4-nonylphenol in 89 breast milk samples was studied. The concentrations of nonylphenol in breast milk were determined by HPLC with fluorescence detection. The lowest and highest concentrations of 4-nonylphenol in breast milk were 0.97 ng/mL and 4.37 ng/mL, respectively. Statistical significance was observed for the consumption of pork (p = 0.048) and fish (0.041) in relation to the 4-nonylphenol concentration. Certain parameters (use of gel nails, beef consumption, and vitamin supplementation) were at the border of statistical significance (p = 0.06). Other parameters did not show any statistical significance. The results showed that breast milk in Slovakia does not contain a harmful dose of 4-nonylphenol and does not cause health problems. But it is necessary to continue this research and perform extended screening on a larger number of samples.

Isomer-specific analysis of nonylphenol and their transformation products in environment: A review

Nonylphenols (NPs) are crucial fine chemicals widely employed in producing industrial and consumer surfactants that ultimately enter the environment through various pathways, leading to environmental pollution. NPs are suspected endocrine-disrupting chemicals that may accumulate in the body over time, resulting in unusual reproductive function. Due to limitations in analytical methods, NPs have typically been quantified as a whole in some studies. However, NPs are a mixture of multibranched structures, and different NP isomers exhibit distinct environmental behaviors and toxic effects. Therefore, it is critical to analyze environmental and human biological samples at the isomer-specific level to elucidate the contamination characteristics, human exposure load, and toxic effects of NPs. Accurately analyzing NP samples with various isomers, metabolites, and transformation products presents a significant challenge. This review summarizes recent advances in analytical research on NPs in technical products, environmental, and human biological samples, particularly emphasizing the synthesis and separation of standards and the transformation of NP homolog isomers in samples. Finally, the review highlights the research gaps and future research directions in this domain.

The effect of long-term exposure to nonylphenol at environmentally relevant levels on mouse liver and adipose tissue

Exposure to the xenoestrogen nonylphenol (NP) during critical windows of development leads to metabolic abnormalities in adult life. However, less is known about NP exposure outside the developmental period on metabolic outcomes. We investigated the effect of prolonged exposure to NP after sexual maturity and at environmentally relevant concentrations below the 'no observable adverse effects level' (0.5 and 2.5 mg/kg/d). Male Swiss mice fed a normal-fat diet exposed to 2.5 mg/kg/d NP showed reduced weight gain and hepatic fat content. In male and female C57BL/6 mice fed a high-fat diet, NP exposure modified the mRNA levels of estrogen receptor α (Esr1) and adipose lineage markers in a sexually dimorphic and adipose depot-dependent pattern. Moreover, in primary female but not male stromal vascular cells from C57BL/6 mouse inguinal WAT induced to differentiate into adipocytes, NP upregulated Fabp4 expression. Low-level exposure to NP outside critical developmental windows may affect the metabolic phenotype distinctly. DATA AVAILABILITY STATEMENT: All data not included in the manuscript, such as raw results, are available upon request and should be addressed to AAA.

Alkylphenols cause cytotoxicity and genotoxicity induced by oxidative stress in RTG-2 cell line

Alkylphenols ethoxylates are industrial surfactants, and the release in the environmental matrices produces degraded products, of which nonylphenol (NP) and octylphenol (OP) were the most common. They can be classified as endocrine disruptors since the estrogenic potential is widely recognized, but some others toxic aspects are in discussion. This study aimed to evaluate the toxicity of NP, OP, and mixtures of both through cellular, biochemical and genetic biomarkers in fish gonadal cell line RTG-2 exposed to nominal concentrations of 0.05; 0.5; 5; 50, and 100 μg mL^-1 of each chemical and their mixtures of 0.05, 0.5; 5 μg mL^-1 concentrations. After 24 h, the cells were collected for cytotoxic (neutral red - NR; crystal violet - CV, resazurin assay - RA and lactate-dehydrogenase - LDH), antioxidant system (glutathione-s-transferase - GST; superoxide-dismutase - SOD; glutathione-peroxidase - GPx and malondialdehyde - MDA) and genotoxic assays (alkaline comet assay and Fpg-modified alkaline comet assay). The chemicals and their mixtures were cytotoxic at 50 and 100 μg mL^-1, in general aspect, but LDH showed cytotoxicity since 0.05 μg mL^-1. The GST and SOD showed an activity increase trend in most tested groups, while GPx decreased at 5 μg mL^-1 of the mixture. The MDA increase in all groups resulted in lipid peroxidation. The reactive oxygen species caused DNA damage for all groups. The tested chemicals and concentrations have been found in the freshwater systems. They can induce cell toxicity in several parameters that could impair the gonadal tissues considering the RTG-2 responses.

A new identity of microcystins: Environmental endocrine disruptors? An evidence-based review

Microcystins (MCs) are widely distributed cyanobacterial toxins in eutrophic waters. At present, the endocrine-disrupting effects of MCs have been extensively studied, but whether MCs can be classified as environmental endocrine disruptors (EDCs) is still unclear. This review is aimed to evaluate the rationality for MCs as to be classified as EDCs based on the available evidence. It has been identified that MCs meet eight of ten key characteristics of chemicals that can be classified as EDCs. MCs interfere with the six processes, including synthesis, release, circulation, metabolism, binding and action of natural hormones in the body. Also, they are fit two other characteristics of EDC: altering the fate of producing/responding cells and epigenetic modification. Further evidence indicates that the endocrine-disrupting effect of MCs may be an important cause of adverse health outcomes such as metabolic disorders, reproductive disorders and effects on the growth and development of offspring. Generally, MCs have endocrine-disrupting properties, suggesting that it is reasonable for them to be considered EDCs. This is of great importance in understanding and evaluating the harm done by MCs on humans.

Contribution of common plastic-related endocrine disruptors to epithelial-mesenchymal transition (EMT) and tumor progression

Many chemicals, including many endocrine disruptors (EDCs) are known to leach out from various plastic consumer products and waste, and are widespread in the environment. EDCs are a large group of contaminants that can interfere with hormonal metabolism or function. In addition, there are in the literature implications of contribution by EDCs in tumor progression, the last stage of carcinogenesis driven by cells with a metastatic phenotype. The process of epithelial cells losing their apical-basal polarity and cell-to-cell contacts, and acquiring migration and invasive properties typical of mesenchymal cells is called epithelial-mesenchymal transition (EMT). It is essential for tumor progression. In human cells, plastic-related EDCs, (phthalates, bisphenol A, and the alkylphenols: nonylphenol and octylphenol) reduce epithelial E-cadherin, and increase mesenchymal N-cadherin and extracellular matrix metalloproteinases. These changes are hallmarks of EMT. In xenograft mouse studies, EDCs increase migration of cells and metastatic growth in distant tissues. Their contribution to EMT and tumor progression, the topic of this review, is important from public health perspective, because of the ubiquitous exposure to these EDCs. In this mini-review we also discuss molecular mechanisms associated with EDC-induced EMT and tumor progression.

Reproduction, skin aging, and sleep in middle-aged women

There is a growing trend for women to delay having children, with a significant number of women postponing motherhood until the third or fourth decade of life. At the same time, these middle-aged women may be more concerned about skin aging and use dermatologic procedures to delay or repair the effects of aging, environmental factors, and oxidative stress on the skin. It has been suggested that the use of skin cosmetics and procedures may play a role in the reproductive system, although their possible effects have not yet been clearly elucidated. Another crucial factor that needs to be raised in this context is poor sleep, which seems to have an important relationship with both reduced fertility and accelerated skin aging, especially when it is associated with greater oxidative stress and hormonal imbalance. This review discusses the important triad of sleep, dermatology, and reproduction, a subject that has received relatively little attention; and, given its potentially wide-ranging implications, one that deserves more frequent and detailed consideration in future studies. Understanding this complex web of interactions could help to provide outcomes that include healthier skin, safety, improved self-esteem, and successful fertility treatments, all of which can directly affect quality of life.

Development of physiologically-based toxicokinetic-toxicodynamic (PBTK-TD) model for 4-nonylphenol (4-NP) reflecting physiological changes according to age in males: Application as a new risk assessment tool with a focus on toxicodynamics

Environmental exposure to 4-nonylphenol (4-NP) is extensive, and studies related to human risk assessment must continue. Especially, prediction of toxicodynamics (TDs) related to reproductive toxicity in males is very important in risk-level assessment and management of 4-NP. This study aimed to develop a physiologically-based-toxicokinetic-toxicodynamic (PBTK-TD) model that added a TD prostate model to the previously reported 4-n-nonylphenol (4-n-NP) physiologically-based-pharmacokinetic (PBPK) model. Modeling was performed under the assumption of similar TKs between 4-n-NP and 4-NP because TK experiments on 4-NP, a random-mixture, are practically difficult. This study was very important to quantitatively predict the TKs and TDs of 4-NP by age at exposure using an advanced PBTK-TD model that reflected physiological-changes according to age. TD-modeling was performed based on the reported toxic effects of 4-NP on RWPE-1 cells, a human-prostate-epithelial-cell-line. Through a meta-analysis of reported human physiological data, body weight, tissue volume, and blood flow rate patterns according to age were mathematically modeled. These relationships were reflected in the PBTK-TD model for 4-NP so that the 4-NP TK and TD changes according to age and their differences could be confirmed. Differences in TK and TD parameters of 4-NP at various ages were not large, within 3.61-fold. Point-of-departure (POD) and reference-doses for each age estimated using the model varied as 426.37-795.24 and 42.64-79.52 μg/kg/day, but the differences (in POD or reference doses between ages) were not large, at less than 1.87-times. The PBTK-TD model simulation predicted that even a 100-fold 4-NP POD_man dose would not have large toxicity to the prostate. With a focus on TDs, the predicted maximum possible exposure of 4-NP was as high as 6.06-23.60 mg/kg/day. Several toxicity-related values estimated by the dose-response curve were higher than those calculated, depending upon the PK or TK, which would be useful as a new exposure limit for prostate toxicity of 4-NP.

Disturbance in Some Fertility Biomarkers Induced and Changes in Testis Architecture by Chronic Exposure to Various Dosages of Each of Nonylphenol or Bisphenol A and Their Mix

This investigation was conducted to demonstrate the potential impacts of different doses of Bisphenol A (BPA) or Nonylphenol (NP) and their mixtures on some biological activities in male albino rats. Seventy male albino rats were allocated to the control group (GI) and were given 1 mL of ethanol. G II and G III were given 100 mg/kg of each of BPA and NP, G IV and G V were given 25 mg/kg of each of BPA and NP, G VI was given a high dose of BPA and NP, and G VII was given a low dose of BPA and NP. All animals were treated orally for 60 days. Serum biomarkers of oxidative stress, antioxidants, immune-inflammatory mediators, and apoptotic markers were determined, as well as a histopathological examination of the testis at the end of the experimental period. The results obtained showed a pronounced increase in malondialdehyde (MDA), protein carbonyl (PC), and 4-hydroxynonenol (4-HNE), concomitant with a significant reduction in serum Superoxide dismutase (SOD), catalase enzyme (CAT), and total antioxidant capacity (TAC) in all treated groups. A significant elevation in TNF Alpha, TNF Beta, and Caspase 3 serum was recorded individually and in the groups treated with high doses. The disturbance is represented by histological damage in the testis in the germinal epithelium and a decrease in spermatozoa inside the lumen of seminiferous tubules. The effects on testis tissues were dose-dependent, pronounced in mixture doses, and remarkable in higher doses. In conclusion, exposure to BPA and NP strongly impacts antioxidants, immune-inflammatory mediators, and testis tissue architecture. Furthermore, the data from this investigation support the idea that exposure to BPA and NP in daily life has multiple damages.

Higher levels of nonylphenol were found in human urine and drinking water from rural areas as compared to metropolitan regions of Wuhan, China

The suspected endocrine disruptor nonylphenol (NP) is closely associated with anthropogenic activities; therefore, studies on this compound have been clustered in urban areas. This study investigated the NP concentrations in drinking water sources (n = 8), terminal tap water (n = 36), and human urine samples (n = 127) collected from urban and rural areas in Wuhan, China. The mean concentrations of NP measured in drinking water sources in urban and rural areas were 92.3 ± 7.5 and 11.0 ± 0.8 ng/L (mean ± SD), respectively, whereas the mean levels in urban and rural tap waters were 5.0 ± 0.7 and 44.2 ± 2.6 ng/L (mean ± SD), respectively. Nevertheless, NP was detected in 74.1% and 75.4% of the human urine samples from urban and rural participants, with geometric mean concentrations of 0.19 ng/mL (0.26 µg/g creat) and 0.27 ng/mL (0.46 µg/g creat), respectively. Although the NP concentrations measured in the drinking water sources of urban areas were significantly higher than those in rural areas (P < 0.05), the tap water and urine NP concentrations measured in urban areas were unexpectedly lower than those of rural areas (P < 0.05). Additionally, this investigation showed that the materials comprising household water supply pipelines and drinking water treatment processes in the two areas were also different. Our results indicated that the levels of exposure to NP in drinking water and human urine in rural areas were not necessarily lower than those in urban areas. Thus, particular attention should be paid to rural areas in future studies of NP.

Mycelium polysaccharides of Macrolepiota procera alleviate reproductive impairments induced by nonylphenol

Nonylphenol (NP) exposure has become a crucial inducement of male reproductive disorders in the world. Therefore, it is urgent to seek solutions to alleviate the toxicity of NP. This study was oriented toward studying the protective effects of Macrolepiota procera mycelium polysaccharides (MMP) on NP-induced reproductive impairments. After NP administration, declined sperm amounts and testis index, increased the deformity rate of sperms, aberrant hormone secretion and testicular pathological injury were observed, corporately leading to reproductive capacity attenuation. Importantly, MMP significantly reversed the foregoing changes in NP-treated mice. Notably, it has been observed that the MMP therapy remarkably improved oxidative stress, apoptosis, autophagy and inflammatory responses, and suppressed the Akt/mTOR signaling pathway in testicular tissues. These results manifested that MMP might be a promising treatment strategy for ameliorating the biotoxicity of NP.

Hair dye use and prostate cancer risk: A prospective analysis in the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study cohort

BACKGROUND

According to the International Agency for Research on Cancer, some hair dye chemicals are considered mutagenic and carcinogenic in humans. One hospital-based study reported a positive association between hair dye use and prostate cancer risk, but no prospective analyses have been conducted.

METHODS

This study investigated the association between hair dye use and prostate cancer risk in the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study cohort, a large, well-characterized cohort of 29,133 male Finnish smokers. Participants completed questionnaires regarding lifestyle, medical, and risk factor information, including the use of hair dye, which was available for 98.8% of the cohort (28,795 men). Prostate cancer cases were identified through linkage with the Finnish Cancer Registry and the Finnish Mortality Register. Hazard ratios (HRs) and confidence intervals (CIs) were estimated via multivariable Cox proportional hazards regression.

RESULTS

During a 28-year period of observation, 2703 incident prostate cancer cases were diagnosed. As reported at the baseline, 75 men used hair dye, and 13 of these men were subsequently diagnosed with prostate cancer. After adjustments for potential confounders, men who used hair dyes experienced substantially higher prostate cancer risk than men who did not (HR, 1.77; 95% CI, 1.03-3.05).

CONCLUSIONS

This first prospective investigation of hair dye use and prostate cancer suggests that personal hair dye use may be related to increased risk. The findings warrant re-examination in other prospective cohorts along with studies evaluating specific hair dyes and possible underlying biological mechanisms.

Environmental estrogens in surface water and their interaction with microalgae: A review

Environmental estrogens (EEs) have received extensive attention because they interfere with biological endocrine and reproduction systems by mimicking, antagonizing, or otherwise affecting the actions of endogenous hormones. Additionally, harmful algal blooms have become a global problem in surface water. Microalgae, as an essential primary producer, is especially important for aquatic life and the entire ecosystem. The presence of EEs in surface water may be a potential promoting factor for algal blooms, and microalgae may have effects on the degradation of EEs. This review focuses on the distribution and pollution characteristics of EEs in global surface waters, effects of single and mixed EEs on microalgae regarding growth and toxin production, mechanisms of EEs on microalgae at the cellular and molecular level. The impacts of microalgae on EEs were also discussed. This review provides a risk assessment of EEs and identifies essential clues that will aid in formulating and revising the relevant standards of surface water regarding EEs, which is significant for ecosystems and human health.

Ligninolytic enzymes in Basidiomycetes and their application in xenobiotics degradation

Variety of microorganisms have already proven their capabilities for degradation of wide range of wastes with anthropogenic nature. These pollutants, both liquid and solids, also include so called xenobiotics like phenol and its derivatives, PAHs, dyes, pesticides, pharmaceuticals, etc. Xenobiotics as bisphenol A (BPA), chlorhexidine (CHX), octenidine (OCT), other disinfectants and antiseptics have high ecotoxicological impact. Moreover, they can also impair our quality of life and our health interfering different metabolic and hormone receptors pathways in human body. Chemical treatment of such wastes is not a viable option because of its poor socio-economics and environmental merits. Therefore, applying effective, ecofriendly and cheap treatment methods is of great importance. Basidiomycetes are extensively investigated for their abilities to degrade numerous pollutants and xenobiotics. Through their extracellular ligninolytic enzymes they are capable of reducing or completely removing wide range of hazardous compounds. These enzymes can be categorized in two groups: oxidases (laccase) and peroxidases (manganese peroxidase, lignin peroxidase, versatile peroxidase). Due to the broad substrate specificity of the secreted enzymes Basidiomycetes can be applied as a powerful tool for bioremediation of diverse xenobiotics and recalcitrant compounds.

Integrated Genomic and Bioinformatics Approaches to Identify Molecular Links between Endocrine Disruptors and Adverse Outcomes

Exposure to Endocrine Disrupting Chemicals (EDC) has been linked with several adverse outcomes. In this review, we examine EDCs that are pervasive in the environment and are of concern in the context of human, animal, and environmental health. We explore the consequences of EDC exposure on aquatic life, terrestrial animals, and humans. We focus on the exploitation of genomics technologies and in particular whole transcriptome sequencing. Genome-wide analyses using RNAseq provides snap shots of cellular, tissue and whole organism transcriptomes under normal physiological and EDC perturbed conditions. A global view of gene expression provides highly valuable information as it uncovers gene families or more specifically, pathways that are affected by EDC exposures, but also reveals those that are unaffected. Hypotheses about genes with unknown functions can also be formed by comparison of their expression levels with genes of known function. Risk assessment strategies leveraging genomic technologies and the development of toxicology databases are explored. Finally, we review how the Adverse Outcome Pathway (AOP) has exploited this high throughput data to provide a framework for toxicology studies.

An Overview of Chemical Additives on (Micro)Plastic Fibers: Occurrence, Release, and Health Risks

Plastic fibers are ubiquitous in daily life with additives incorporated to improve their performance. Only a few restrictions exist for a paucity of common additives, while most of the additives used in textile industry have not been clearly regulated with threshold limits. The production of synthetic fibers, which can shed fibrous microplastics easily (< 5 mm) through mechanical abrasion and weathering, is increasing annually. These fibrous microplastics have become the main composition of microplastics in the environment. This review focuses on additives on synthetic fibers; we summarized the detection methods of additives, compared concentrations of different additive types (plasticizers, flame retardants, antioxidants, and surfactants) on (micro)plastic fibers, and analyzed their release and exposure pathways to environment and human beings. Our prediction shows that the amounts of predominant additives (phthalates, organophosphate esters, bisphenols, per- and polyfluoroalkyl substances, and nonylphenol ethoxylates) released from clothing microplastic fibers (MFs) are estimated to reach 35, 10, 553, 0.4, and 568 ton/year to water worldwide, respectively; and 119, 35, 1911, 1.4, and 1965 ton/year to air, respectively. Human exposure to MF additives via inhalation is estimated to be up to 4.5–6440 µg/person annually for the above five additives, and via ingestion 0.1–204 µg/person. Notably, the release of additives from face masks is nonnegligible that annual human exposure to phthalates, organophosphate esters, per- and polyfluoroalkyl substances from masks via inhalation is approximately 491–1820 µg/person. This review helps understand the environmental fate and potential risks of released additives from (micro)plastic fibers, with a view to providing a basis for future research and policy designation of textile additives.

Steatosis induced by nonylphenol in HepG2 cells and the intervention effect of curcumin

Non-alcoholic fatty liver disease (NAFLD) has increasingly become a serious public health problem. There is growing evidence that nonylphenol (NP) exposure may cause steatosis, but the underlying mechanism is not fully understood. Curcumin (CUR) improves NAFLD-related lipid metabolism disorders and oxidative stress, but its preventive and therapeutic effects on NP-induced steatosis have not been reported. The objective of this investigation was to determine the capability and potential mechanism of NP to induce steatosis in vitro and the intervention of curcumin. HepG2 cells were treated with 0 μM, 20 μM, 30 μM, 40 μM NP for 24 h. Lipid droplets accumulated significantly in HepG2 cells after NP treatment, and the concentration of triglyceride (TG) and total cholesterol (T-CHO) increased significantly. Simultaneously, lipogenesis gene expression was up-regulated significantly, fatty acid oxidation (FAO) gene expression was significantly down-regulated, and reactive oxygen species (ROS) were overproduced. Meanwhile, the expression of p-AMPK/AMPK in the AMPK/mTOR signaling pathway was significantly down-regulated and the expression of p-mTOR/mTOR was markedly up-regulated. However, blocking ROS production with N-acetyl-L-cysteine (NAC) can reverse these phenomena. In addition, our study found that curcumin effectively ameliorated the effects of NP-induced steatosis. Our study indicates that NP can induce steatosis in HepG2 cells, and may be implicated in inhibiting the ROS-dependent AMPK/mTOR pathway, and that curcumin ameliorates the NAFLD-like changes induced by NP in HepG2 cells.

Highly efficient adsorption and mechanism of alkylphenols on magnetic reduced graphene oxide

The influence of alkylphenols to environment cannot be ignored, as they are common product from chemical industries and potential threat to human health. Some alkylphenols are listed as persistent toxic substances (PTS) by the United Nations Environment Programme (UNEP). In this study, the optimized magnetic reduced graphene oxide (MrGO) was synthesized by a facile solvothermal method, and investigated for adsorption of three typical alkylphenols. In neutral condition, MrGO showed extremely high adsorption capacity of three typical alkylphenols, 4-heptylphenol (4-HP), 4-tert-octylphenol (4-OP), and 4-nonylphenol (4-NP), which could reach 938.9 mg g^-1 (40 °C), 987.8 mg g^-1 (40 °C), and 989.7 mg g^-1 (20 °C), respectively. This study revealed that the adsorption process was a heterogeneous multi-layer physical adsorption, and the adsorption rates were related to the number of unoccupied vacancies on the adsorbent surface. From batch experiments and density functional theory (DFT) calculations, the main adsorption interactions between MrGO and alkylphenols were deduced to be π-π, hydrogen-bond, and hydrophobic interactions. What's more, the different affinities of MrGO towards different targets were further distinguished and explained in detail. The wonderful stability and recyclability of MrGO made it a promising cost-effective remediation candidate.

An approach to classifying occupational exposures to endocrine disrupting chemicals by sex hormone function using an expert judgment process

Endocrine disrupting chemicals (EDCs) are exogenous substances that interfere with the endocrine system and cause adverse effects. We aimed to classify the effects of 24 known EDCs, prevalent in certain occupations, according to four modes of action (estrogenic, antiestrogenic, androgenic, and/or antiandrogenic). A literature search, stratified into four types of literature was conducted (namely: national and international agency reports; review articles; primary studies; ToxCast^TM). The state of the evidence of each EDC on sex hormone function was summarized and reviewed by an expert panel. For each mode of action, the experts evaluated the likelihood of endocrine disruption in five categories: "No", "Unlikely", "Possibly", "Probably", and "Yes". Seven agents were categorized as "Yes," or having strong evidence for their effects on sex hormone function (antiandrogenic: lead, arsenic, butylbenzyl phthalate, dibutyl phthalate, dicyclohexyl phthalate; estrogenic: nonylphenol, bisphenol A). Nine agents were categorized as "Probable," or having probable evidence (antiandrogenic: bis(2-ethylhexyl)phthalate, nonylphenol, toluene, bisphenol A, diisononyl phthalate; androgenic: cadmium; estrogenic: copper, cadmium and; anti-estrogenic: lead). Two agents (arsenic, polychlorinated biphenyls) had opposing conclusions supporting both "probably" estrogenic and antiestrogenic effects. This synthesis will allow researchers to evaluate the health effects of selected EDCs with an added level of precision related to the mode of action.

Analytical methods for the determination of endocrine disrupting chemicals in cosmetics and personal care products: A review

Personal care products (PCPs) and cosmetics are indispensable product in our daily routine. Their widespread use makes them a potential route of exposure for certain contaminants to which human would not be normally exposed. One of these contaminants includes endocrine disrupting chemicals, molecules capable of mimicking the body's natural hormones and interfering with the endocrine system. Some of them are ingredients included in the product's formulation, such as UV-filters (sunscreens), phthalates (plasticizers and preservatives), synthetic musks (fragrances), parabens and other antimicrobial agents (antimicrobial preservatives). Others are non-intended added substances that may result from the manufacturing process or migration from the plastic packaging, as with bisphenols and perfluorinated compounds. Some of these endocrine disruptors have been restricted or even banned in cosmetics and PCPs given the high risk they pose to health. Thus, the development of fast, sensitive and precise methods for the identification and quantification of these compounds in cosmetics is a substantial need in order to ensure consumer safety and provide insight into the real risk of human exposure. The present work aims at reviewing the more recently developed analytical methods published in the literature for the determination of endocrine disrupting chemicals in cosmetics and PCPs using chromatographic techniques, with a focus on sample treatment and the quality of analytical parameters.

Protective effect of myricetin on nonylphenol-induced testicular toxicity: biochemical, steroidogenic, hormonal, spermatogenic, and histological-based evidences

Nonylphenol (NP) is an environmental contaminant, which induces testicular toxicity through oxidative stress. Myricetin (MYR) is a naturally occurring flavonol having powerful antioxidant activity. The current research was planned to examine the ameliorative role of MYR against NP-induced testicular damage. A total of 24 adult male Sprague-Dawley rats were randomly divided into 4 equivalent groups: control (0.1% DMSO), NP group (50 mg kg-1), NP + MYR group (50 mg kg-1; 100 mg kg-1), and MYR-treated group (100 mg kg-1). NP administration significantly (p < 0.05) decreased the activity of antioxidant enzymes, including catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione reductase (GSR), and protein content while significantly (p < 0.05) elevating the thiobarbituric acid reactive substances (TBARS) and reactive oxygen species (ROS) levels. Additionally, NP significantly (p < 0.05) reduced the sperm motility, gene expression of testicular steroidogenic enzymes (3β-HSD, 3β-hydroxysteroid dehydrogenase; 17β-HSD, 17β-hydroxysteroid dehydrogenase; StAR, steroidogenic-acute regulatory protein), level of luteinizing hormone (LH), follicle-stimulating hormone (FSH), plasma testosterone, and daily sperm production (DSP). On the other hand, it raised the testicular cholesterol, dead sperms, and head, midpiece, and tail abnormalities along with abnormal histomorphometry. However, MYR remarkably abrogated NP-induced damages. In conclusion, the outcomes of the study suggest that MYR can effectively alleviate the NP-induced oxidative stress and testicular damages.

Multigenerational reproduction and developmental toxicity, and HPG axis gene expression study on environmentally-relevant concentrations of nonylphenol in zebrafish

Nonylphenol (NP) is a toxic xenobiotic compound, which is persistent in the aquatic environment and is extremely toxic to aquatic organisms. Although the exact molecular mechanisms of its toxic effect are well understood, the multigenerational reproduction and multigenerational - gene expression changes caused by NP still remain unclear. The following work investigated the effect of NP on four consecutive generations of zebrafish by examining their growth and several reproductive parameters, the degree of gonad damage, and the expression of related reproduction related genes. The results showed that high concentrations (20 and 200 μg·L^-1) of NP could decrease growth and induce gonad damage in zebrafish. In addition, gnrh2 and gnrh3 genes were up-regulated, and fshβ and lhβ genes were downregulated in the hypothalamus in male zebrafish; while in female fish, the fshβ and lhβ were upregulated in P and F1 generations, and then down-regulated in the F2 generation. Meanwhile, the cyp19a1a gene was downregulated in the gonad of male fish, while the genes of fshr, lhr and esr showed a downward trend in females. Compared to P generation, F2 generation was more tolerant to higher NP concentrations (20 and 200 μg·L^-1), as was also more sensitive to lower concentrations of NP (2 μg·L^-1). Consequently, stress and damage caused by environmentally-relevant concentrations of aquatic pollutants in a vertebrate model were measured and predicted. Prevention and control measures can be actively and effectively proposed, which might be transversal to other exposed organisms, including humans. After several generations, typical transgenerational genetic phenomena might occur, which should be addressed by further studies.

White rot fungi can be a promising tool for removal of bisphenol A, bisphenol S, and nonylphenol from wastewater

Endocrine-disrupting chemicals (EDC) are a wide group of chemicals that interfere with the endocrine system. Their similarity to natural steroid hormones makes them able to attach to hormone receptors, thereby causing unfavorable health effects. Among EDC, bisphenol A (BPA), bisphenol S (BPS), and nonylphenol (NP) seem to be particularly harmful. As the industry is experiencing rapid expansion, BPA, BPS, and NP are being produced in growing amounts, generating considerable environmental pollution. White rot fungi (WRF) are an economical, ecologically friendly, and socially acceptable way to remove EDC contamination from ecosystems. WRF secrete extracellular ligninolytic enzymes such as laccase, manganese peroxidase, lignin peroxidase, and versatile peroxidase, involved in lignin deterioration. Owing to the broad substrate specificity of these enzymes, they are able to remove numerous xenobiotics, including EDC. Therefore, WRF seem to be a promising tool in the abovementioned EDC elimination during wastewater treatment processes. Here, we review WRF application for this EDC removal from wastewater and indicate several strengths and limitations of such methods.

Histological Analysis of Reproductive System in Low-Dose Nonylphenol-treated F1 Female Mice

Previously, we reported adverse effects of low-dose nonylphenol (NP) exposure on the reproductive parameters of F1 female mice. In the present study we further investigated the pathohistological effect of NP exposure on the reproductive organs in F1 female mice. NP exposures were continuously conducted from parental pre-mating period until the postnatal day (PND) 33 of F1 offspring for vaginal examination. Mice were sacrificed on PND 30 and the reproductive tissue weights were measured. The initial (at PND 21) body weights of the NP-50 group animals were significantly lower than those of control group animals, and the weight deficit were recovered when the terminal (PND 33) body weights were measured. Early vaginal opening was found in NP group animals (p<0.05). Pathohistological studies revealed that NP-treated F1 animals showed prominent increase in the ovarian follicle numbers (p<0.01), and decrease in the diameter of uterine myometrium (p<0.01), and increase in the diameter of luminal epithelium (p<0.05). The present study demonstrated that the subchronic low-dose NP exposure induced early beginning of puberty and pathohistological abnormalities in ovary and uterus of F1 mice. Further studies are needed to achieve a better understanding on the action mechanism of NP in pubertal onset and to find a way to avoid a hazardous situation provoked by NP exposure.

Oxidative Stress and Apoptosis Contributed to Nonylphenol-Induced Cell Damage in Mouse NCTC Clone 1469 Cells

Nonylphenol (NP) is considered an environmental toxicant and endocrine-disrupting compound. The present study aimed to investigate the effects of NP on NCTC Clone 1469, nonparenchymal hepatocytes, and to study the molecular basis of NP-induced liver injury. The results showed that NP decreased cell viability and induced nucleus crenulation and intracellular enzyme leakage in NCTC Clone 1469 cells. Additionally, NP-induced oxidative stress and apoptosis of NCTC Clone 1469 are accompanied by upregulating reactive oxygen species (ROS) production, increase of Bax, decrease of Bcl-2, activation of caspase-3 and caspase-12, and release of cytosolic free Ca2+ in the cells. ROS scavenger, N-acetyl-L-cysteine (NAC), prevented the intracellular enzyme leakage induced by NP. NP induced alteration of estrogen receptor- (ER-) α and ER-β expression, while ER antagonists, ICI 182,780, showed no effect on NP-induced intracellular enzyme leakage. We proposed that NP triggered cell damage via inducing oxidative stress and apoptosis in cells, but not estrogenic effect.

Polysaccharide from the seeds of Plantago asiatica L. alleviates nonylphenol induced intestinal barrier injury by regulating tight junctions in human Caco-2 cell line

The intestinal epithelium is known as an important barrier to protect the body from harmful pathogens or toxic substance that may induce intestinal barrier injury. The aim of this study was to investigate the effects of polysaccharide from the seeds of Plantago asiatica L. (PLP) on nonylphenol (NP) induced intestinal barrier injury in vitro. Caco-2 cells were pretreated with PLP, or co-cultured with PLP and NP simultaneously, and cytotoxicity, LDH leakage, transepithelial electrical resistance (TEER), FITC-dextran flux and tight junction (TJ) proteins were conducted to evaluate the intestinal barrier function. The results suggested that PLP pretreatment or co-culture with NP could significantly attenuated NP induced Caco-2 cytotoxicity, suppressed LDH release, restored the TEER value and paracellular permeability of Caco-2 monolayers, which were attributed to enhancing the TJ protein expressions. In addition, PLP co-cultured with NP possessed better protective effects against NP induced cytotoxicity. This study indicated that PLP assuaged NP induced intestinal barrier injury by increasing TJ, and threw light on the development of a dietary supplementation for preventing exogenous toxic substances induced intestinal barrier injury or improving intestinal TJ barrier function.

Perinatal exposure to nonylphenol delayed myelination in offspring cerebellum

As a stable environmental contaminant, nonylphenol (NP) has been shown to induce some neurological deficits in the cerebellum, although the underlying mechanism is still unknown. In the present study, we aimed to investigate the effects of perinatal exposure to NP on myelination, an important process essential for the intact cerebellar function, in the offspring cerebellum. Exposure to NP delayed the myelination in the offspring cerebellum during perinatal period. The myelination recovered in the cerebellum of offspring exposed to NP over time, and returned to normal in adulthood. In addition, perinatal exposure to NP reduced mature oligodendrocytes (myelin-forming glial cells) and increased astrocytes in the offspring cerebellum. BMP signaling is believed to negatively regulate oligodendrogliogenesis and myelination. In the present study, BMP4, p-Smad1/5, and ID4, key members of BMP signaling, were increased in the cerebellum of offspring exposed to NP. Taken together, these lines of evidence suggest that the activation of BMP signaling may underlie the decreased oligodendrogliogenesis and increased astrogliogenesis, and the consequent delay of myelination in the cerebellum of offspring perinatally exposed to NP.

Endocrine-disrupting chemicals rapidly affect intercellular signaling in Leydig cells

A decline in male fertility possibly caused by environmental contaminants, namely endocrine-disrupting chemicals (EDCs), is a topic of public concern and scientific interest. This study addresses a specific role of testicular gap junctional intercellular communication (GJIC) between adjacent prepubertal Leydig cells in endocrine disruption and male reproductive toxicity. Organochlorine pesticides (lindane, methoxychlor, DDT), industrial chemicals (PCB153, bisphenol A, nonylphenol and octylphenol) as well as personal care product components (triclosan, triclocarban) rapidly dysregulated GJIC in murine Leydig TM3 cells. The selected GJIC-inhibiting EDCs (methoxychlor, triclosan, triclocarban, lindane, DDT) caused the immediate GJIC disruption by the relocation of gap junctional protein connexin 43 (Cx43) from the plasma membrane and the alternation of Cx43 phosphorylation pattern (Ser368, Ser279, Ser282) of its full-length and two N-truncated isoforms. After more prolonged exposure (24 h), EDCs decreased steady-state levels of full-length Cx43 protein and its two N-truncated isoforms, and eventually (triclosan, triclocarban) also tight junction protein Tjp-1. The disturbance of GJIC was accompanied by altered activity of mitogen-activated protein kinases MAPK-Erk1/2 and MAPK-p38, and a decrease in stimulated progesterone production. Our results indicate that EDCs might disrupt testicular homeostasis and development via disruption of testicular GJIC, a dysregulation of junctional and non-junctional functions of Cx43, activation of MAPKs, and disruption of an early stage of steroidogenesis in prepubertal Leydig cells. These critical disturbances of Leydig cell development and functions during a prepubertal period might be contributing to impaired male reproduction health later on.

Exposure to nonylphenol in early life increases pro-inflammatory cytokines in the prefrontal cortex: Involvement of gut-brain communication

A growing body of evidence indicates that exposure to nonylphenol (NP), a typical persistent organic pollutant (POP), in early life results in the impairment of the central nervous system (CNS), but the underlying mechanism still remains to be elucidated. High levels of pro-inflammatory cytokines in the brain have been implicated in the CNS damages. The animal model of exposure to NP in early life was established by maternal gavage during the pregnancy and lactation in the present study. We found that exposure to NP in early life increased the levels of pro-inflammatory cytokines in the rat prefrontal cortex. Interestingly, the levels of pro-inflammatory cytokines in the intestine as well as in the serum were also increased by NP exposure. Furthermore, the increased permeability of intestinal barrier and blood-brain barrier (BBB), two critical barriers in the gut to brain communication, was observed in the rats exposed to NP in early lives. The decreased expression of zonula occludens-1 (ZO-1) and claudin-1 (CLDN-1), tight junction proteins (TJs) that responsible for maintaining the permeability of intestinal barrier and BBB, was found, which may underlie these increases in permeability. Taken together, these results suggested that the disturbed gut-brain communication may contribute to the increased levels of pro-inflammatory cytokines in the prefrontal cortex caused by NP exposure in early life.

Toxic Effects of Nonylphenol on Neonatal Testicular Development in Mouse Organ Culture

Nonylphenol (NP) is an alkylphenol that is widely used in chemical manufacturing. Exposure to this toxic environmental contaminant has been shown to negatively affect the reproductive system. Herein, we evaluated the toxicity of NP in mouse testes, while using in vitro organ culture. Mouse testicular fragments (MTFs), derived from five-day postpartum neonatal mouse testes, were exposed to different concentrations of NP (1-50 μM) for 30 days. The results showed that NP impaired germ cell development and maintenance. Furthermore, NP significantly downregulated the transcript levels of both undifferentiated and differentiated germ cell marker genes relative to those in controls. In particular, a high dose of NP (50 µM) led to complete germ cell depletion and resulted in spermatogenic failure, despite the presence of Sertoli and Leydig cells. In addition, the mRNA expression of steroidogenic enzymes, such as steroidogenic acute regulatory protein (STAR), Cytochrome P450 Family 11 Subfamily A Member 1 (Cyp11α1), Cytochrome P450 17A1 (Cyp17α1), and androgen receptor (AR), increased with increasing concentration of NP. Conversely, the expression of estrogen receptor alpha (ESR1) and Cytochrome P450 family 19 subfamily A member 1 (Cyp19α1) in NP-exposed MTFs decreased when compared to that of the control. Taken together, this study demonstrates that NP has a negative effect on prepubertal spermatogenesis and germ cell maintenance and it disrupts steroidogenesis and induces hormonal imbalance in MTFs.

Adverse Effect of Nonylphenol on the Reproductive System in F2 Male Mice : A Qualitative Change?

Previously, we reported negative effects of low-dose nonylphenol (NP) exposure on the reproductive organs of F1 male mice. In the present study was further investigated the endocrine disrupting effect of NP exposure to F2 generation male mice. Mice were divided into 2 groups; (1) CON, control animals and (2) NP-50 (50 μg/L), animals were treated with NP via drinking water. NP exposures were continuously conducted from parental pre-mating period until the postnatal day (PND) 55 of F2 offsprings. Mice were sacrificed on PND 55 and the reproductive tissue weights were measured. The initial (at PND 21) and terminal (PND 55) body weights of the NP-50 group animals were not significantly different from those of control group animals. NP exposure fail to induce a significant weight change of the testes, seminal vesicle and prostate except absolute epididymal weight (p<0.05). However, pathohistological studies revealed that NP-treated F2 animals showed evident decrease in seminiferous tubule diameters, reduced luminal area and number of germ cells. Also, sloughing morphologies in the tubules were notable. In the caudal epididymis, fewer mature sperms and swollen epithelial cells were found in the NP-treated group. The present study demonstrated that the subchronic low-dose NP exposure induced pathohistological abnormalities in testis and epididymis of F2 mice, and we assumed that these ‘qualitative’ changes in reproductive tissues could be derived from the epigenetic modifications such as DNA methylation, histone modification, altered DNA accessibility and chromatin structure. Further studies are needed to achieve a better understanding on the multi- or trans-generational effects of NP on the reproductive health and a human application.

Ecological risks of phenolic endocrine disrupting compounds in an urban tropical river

The distribution of emerging organic contaminants in drinking water sources in Africa is a subject with very scanty data and information. In order to fill knowledge gaps, we report here the distribution and potential ecological risks of three phenolic compounds (bisphenol A (BPA), 4-nonylphenol (NP), and 4-tert-octylphenol (OP)), which have been previously identified to have the potential of endocrine disrupting activity, in surface water and sediment of the New Calabar River. The compounds were quantified using GC-MS. At all sampling sites, a similar concentration pattern of BPA > NP > OP was recorded, with the exception of Choba sampling station in which the levels of these endocrine disrupting compounds were low or undetectable. The levels of BPA in surface water ranged from 1.20 to 63.64 μg/L, whereas those of NP and OP ranged from < 0.20 to 2.15 μg/L and from < 0.10 to 0.68 μg/L, respectively. For sediments, measured levels were from 1.20 to 66.57 μg/kg for BPA, from < 0.35 to 3.37 μg/kg for NP, and from < 0.13 to 0.90 μg/kg for OP. Risk quotients (RQs) assessed for some sensitive organisms (algae, Daphnia magna, and fish) were above 1 for BPA and NP, whereas RQs for OP were below 1. This implies that BPA and NP at the levels detected could have potential risks to the sensitive organisms considered, but low risk for OP.

Adverse Effect of Nonylphenol on the Reproductive System in F1 Male Mice: A Subchronic Low-Dose Exposure Model

Nonylphenols (NPs) are widely used industrial materials, and are considered as potent endocrine disrupting chemical. Present study was undertaken to clarify the effect of subchronic low-dose NP exposure to F1 generation male mice. Mice were divided into 2 groups; (1) CON, control animals and (2) NP-50 (50 μg/L), animals were treated with NP via drinking water. NP exposures were continuously conducted from parental pre-mating period until the postnatal day (PND) 55 of F1 offsprings. Mice were sacrificed on PND 55 and the tissue weights were measured. The initial body weights (at PND 21) and terminal body weights (PND 55) of the NP-50 animals were significantly lower than those of control animals (p<0.05). NP exposure induced a significant increase in the absolute weight of the testes (p<0.05). Conversely, the NP exposure caused significant decrease in the absolute weights of the epididymis (p<0.01), prostate (p<0.05) and seminal vesicle (p<0.05). Histopathological studies revealed that NP-treated animals exerted decreased seminiferous tubule diameters, reduced luminal area, and lower number of germ cells. Also some sloughing morphologies in the tubules were observed. In the caudal epididymis, fewer mature sperms and swollen epithelial cells were found in the NP-treated group. Our results confirmed that the subchronic low-dose NP exposure altered some male parameters and induced histopathological abnormalities in testis and epididymis of F1 mice. Since the NP dose used in this study is close to the average human daily NP exposure, our results could provide practically meaningful understanding of adverse effect of EDC in human.

Effects of maternal exposure to nonylphenol on learning and memory in offspring involve inhibition of BDNF-PI3K/Akt signaling

Nonylphenol (NP), a global environmental pollutant, has been found to result in impairments of neurodevelopment. However, effects of maternal exposure to NP on learning and memory and the potential mechanisms are largely unexplored. Thus, we treated dams with NP during gestation and lactation to study its effect on learning and memory in offspring. Morris water maze (MWM) task and the electrophysiological recording in the hippocampus were conducted in pups. We also investigated the activation of BDNF-PI3K/Akt signaling and the expression of its target protein PSD-95 in offspring hippocampus, which are curial for the synaptic plasticity and learning and memory. The results showed that maternal exposure to NP led to poor performance in MWM task and especially impairments of long-term potentiation (LTP), although the termination of NP exposure was at the end of lactation. Meanwhile, maternal exposure to NP also decreased the activation of BDNF-PI3K/Akt signaling and the protein level of PSD-95. Taken together, our results support the hypothesis that maternal exposure to NP during gestation and lactation causes damages to learning and memory. In addition, suppressed activation of the BDNF-PI3K/Akt signaling may contribute to these impairments caused by maternal exposure to NP.

4-Nonylphenol effects on rat testis and sertoli cells determined by spectrochemical techniques coupled with chemometric analysis

Herein, vibrational spectroscopy has been applied for qualitative identification of biomolecular alterations that occur in cells and tissues following chemical treatment. Towards this end, we combined attenuated total reflection Fourier-transform infrared (ATR-FTIR) and Raman spectroscopy to assess testicular toxicology after 4-nonylphenol (NP) exposure, an estrogenic endocrine disruptor affecting testicular function in rats and other species. Rats aged 21, 35 or 50 days received NP at intra-peritoneal doses of 0, 25, 50 or 100 mg/kg for 20 consecutive days. Primary Sertoli cells (SCs) were treated with NP at various concentrations (0, 2.5, 5, 10 or 20 μM) for 12 h. Post-exposure, testicular cells, interstitial tissue and SCs were interrogated respectively using spectrochemical techniques coupled with multivariate analysis. Distinct biomolecular segregation between the NP-exposed samples vs. control were observed based on infrared (IR) spectral regions of 3200-2800 cm^-1 and 1800-900 cm^-1, and the Raman spectral region of 1800-900 cm^-1. For in vivo experiments, the main wavenumbers responsible for segregation varied significantly among the three age classes. The main IR and Raman band differences between NP-exposed and control groups were observed for Amide (proteins), lipids and DNA/RNA. An interesting finding was that the peptide aggregation level, Amide Ӏ-to-Amide II ratio, and phosphate-to-carbohydrate ratio were considerably reduced in ex vivo NP-exposed testicular cells or SCs in vitro. This study demonstrates that ATR-FTIR and Raman spectroscopy techniques can be applied towards analysing NP-induced testicular biomolecular alterations.

Assessing effects of germline exposure to environmental toxicants by high-throughput screening in C. elegans

Chemicals that are highly prevalent in our environment, such as phthalates and pesticides, have been linked to problems associated with reproductive health. However, rapid assessment of their impact on reproductive health and understanding how they cause such deleterious effects, remain challenging due to their fast-growing numbers and the limitations of various current toxicity assessment model systems. Here, we performed a high-throughput screen in C. elegans to identify chemicals inducing aneuploidy as a result of impaired germline function. We screened 46 chemicals that are widely present in our environment, but for which effects in the germline remain poorly understood. These included pesticides, phthalates, and chemicals used in hydraulic fracturing and crude oil processing. Of the 46 chemicals tested, 41% exhibited levels of aneuploidy higher than those detected for bisphenol A (BPA), an endocrine disruptor shown to affect meiosis, at concentrations correlating well with mammalian reproductive endpoints. We further examined three candidates eliciting aneuploidy: dibutyl phthalate (DBP), a likely endocrine disruptor and frequently used plasticizer, and the pesticides 2-(thiocyanomethylthio) benzothiazole (TCMTB) and permethrin. Exposure to these chemicals resulted in increased embryonic lethality, elevated DNA double-strand break (DSB) formation, activation of p53/CEP-1-dependent germ cell apoptosis, chromosomal abnormalities in oocytes at diakinesis, impaired chromosome segregation during early embryogenesis, and germline-specific alterations in gene expression. This study indicates that this high-throughput screening system is highly reliable for the identification of environmental chemicals inducing aneuploidy, and provides new insights into the impact of exposure to three widely used chemicals on meiosis and germline function.

The ever-increasing number of new chemicals introduced into our environment poses a significant problem for risk assessment. In addition, assessing the direct impact of toxicants on human meiosis remains challenging. We successfully utilized a high-throughput platform in the nematode C. elegans, a genetically tractable model organism which shares a high degree of gene conservation with humans, to identify chemicals that affect the germline leading to aneuploidy. We assessed chemicals that are highly prevalent in the environment in worms carrying a fluorescent reporter construct allowing for the identification of X chromosome nondisjunction combined with a mutation increasing cuticle permeability for analysis of low doses of exposure. Follow up analysis of three chemicals: DBP, permethrin and TCMTB, further validated the use of this strategy. Exposure to these chemicals resulted in elevated levels of DNA double-strand breaks, activation of a DNA damage checkpoint, chromosome morphology defects in late meiotic prophase I as well as impaired early embryogenesis and germline-specific changes in gene expression. Our results support the use of this high-throughput screening system to identify environmental chemicals inducing aneuploidy, and provide new insights into the effects of exposure to DBP, permethrin, and TCMTB on meiosis and germline function.

Perinatal exposure to nonylphenol impairs dendritic outgrowth of cerebellar Purkinje cells in progeny

Nonylphenol (NP) is a commercially produced nonionic surfactant that has become a global environmental pollutant due to poor biodegradability. Many studies have confirmed that NP has detrimental effects on the central nervous system. However, the damaging roles of NP on the cerebellum and the underlying mechanisms remain unclear. Therefore, we investigated the effects of perinatal exposure to NP on cerebellar Purkinje cell (PC) dendrites and explored the potential mechanism involved. The animal model of perinatal exposure to NP was established by orally administering dams with either corn oil or NP (10, 50, or 100 mg/kg) during pregnancy and lactation. Offspring subjected to NP exposure during pregnancy and lactation had shorter and fewer cerebellar PC dendritic branches in childhood (postnatal day (PND)21) and adulthood (PND80). Contrary to expectations, perinatal NP treatment increased phosphorylation of protein kinase C gamma on PND21, but not on PND80. However, perinatal exposure to NP decreased phosphorylation of stathmin and tropomyosin-related kinase B (TrkB), as well as the expression of brain derived neurotrophic factor (BDNF) in cerebellar PCs on PND21 and PND80. These results indicate that perinatal exposure to NP irreversibly inhibited dendritic growth of PCs in the cerebella of offspring. Furthermore, the irreversible damage to PC dendrites in the cerebella of offspring subjected to perinatal NP exposure may be due to increased stathmin activity mediated by BDNF-TrkB signaling.

The possible DNA damage induced by environmental organic compounds: The case of Nonylphenol

Human impact on the environment leads to the release of many pollutants that produce artificial compounds, which can have harmful effects on the body's endocrine system; these are known as endocrine disruptors (EDs). Nonylphenol (NP) is a chemical compound with a nonyl group that is attached to a phenol ring. NP-induced H₂AX is a sensitive genotoxic biomarker for detecting possible DNA damage; it also causes male infertility and carcinogenesis. We attempt to comprehensively review all the available evidence about the different ways with descriptive mechanisms for explaining the possible DNA damage that is induced by NP. We systematically searched several databases, including PubMed, Scopus, Web of Science, and gray literature, such as Google Scholar by using medical subheading (MeSH) terms and various combinations of selected keywords from January 1970 to August 2017. The initial search identified 62,737 potentially eligible studies; of these studies, 33 were included according to the established inclusion criteria. Thirty-three selected studies, include the topics of animal model (n = 21), cell line (n = 6), human model (n = 4), microorganisms (n = 1), solid DNA (n = 1), infertility (n = 4), apoptosis (n = 6), and carcinogenesis (n = 3). This review highlighted the possible deleterious effects of NP on DNA damage through the ability to produce ROS/RNS. Finally, it is significant to observe caution at this stage with the continued use of environmental pollutants such as NP, which may induce DNA damage and apoptosis.

Potential Health Risk of Endocrine Disruptors in Construction Sector and Plastics Industry: A New Paradigm in Occupational Health

Endocrine disruptors (EDs) belong to large and diverse groups of agents that may cause multiple biological effects associated with, for example, hormone imbalance and infertility, chronic diseases such as diabetes, genome damage and cancer. The health risks related with the exposure to EDs are typically underestimated, less well characterized, and not regulated to the same extent as, for example, carcinogens. The increased production and utilization of identified or suspected EDs in many different technological processes raises new challenges with respect to occupational exposure settings and associated health risks. Due to the specific profile of health risk, occupational exposure to EDs demands a new paradigm in health risk assessment, redefinition of exposure assessment, new effects biomarkers for occupational health surveillance and definition of limit values. The construction and plastics industries are among the strongest economic sectors, employing millions of workers globally. They also use large quantities of chemicals that are known or suspected EDs. Focusing on these two industries, this short communication discusses: (a) why occupational exposure to EDs needs a more specific approach to occupational health risk assessments, (b) identifies the current knowledge gaps, and (c) identifies and gives a rationale for a future occupational health paradigm, which will include ED biomarkers as a relevant parameter in occupational health risk assessment, surveillance and exposure prevention.

Adult male mice exposure to nonylphenol alters courtship vocalizations and mating

The neural circuitry processing male sexual behavior is tightly regulated by testosterone and its neural metabolite estradiol. The present study evaluated the effects of adult exposure to low doses of nonylphenol (NP), a widespread environmental contaminant, on the neuroendocrine regulation of testosterone and expression of sexual behavior. Oral exposure of C57BL/6J males to NP (0.5, 5 or 50 μg/kg/day) for 4 weeks did not affect circulating levels of testosterone or the kisspeptin system, a key regulator of the gonadotropic axis. In contrast, mice exposed to NP at 5 μg/kg/day emitted an increased number and duration of ultrasonic vocalizations, took longer to reach ejaculation and showed increased number of mounts, intromissions and thrusts. This was associated with normal olfactory preference and locomotor activity, and increased anxiety level. Analysis of the neural circuitry that underlies sexual behavior showed changes in the number of cells expressing androgen and estrogen receptors in males exposed to NP at 5 μg/kg/day. The neural circuitry underlying sexual behavior is thus highly sensitive to adult exposure to NP. Furthermore, almost all the observed effects were induced at 5 μg/kg/day of NP, indicating that this endocrine disrupter triggers a non-monotonic response in the adult male mouse brain.

The adverse effects of chronic low-dose exposure to nonylphenol on type 2 diabetes mellitus in high sucrose-high fat diet-treated rats

OBJECTIVES

Although it has been shown that exposure to environmental endocrine disruptors (EDCs) has been implicated as a potential risk factor for metabolic disease, information on adverse effect of chronic low-dose exposure to nonylphenol (NP), on the development and progress of type 2 diabetes mellitus (T2DM) is scarce. NP, as an EDC, is a ubiquitous degradation product of nonylphenol polyethoxylate (NPE) that is primarily used in cleaning and industrial processes.

METHOD

Eighty Sprague-Dawley rats were assigned into 8 groups (n = 10 per group): rats fed a normal-diet (ND) as the control (C-ND); rats fed a normal diet and were gavaged with NP at a dose level of 0.02 μg/kg/day (NP-L-ND), 0.2 μg/kg/day (NP-M-ND) or 2 μg/kg/day (NP-H-ND), respectively; rats fed a high-sucrose/high-fat diet (HSHFD) as the HSHFD control (C-HSHFD); rats fed a HSHFD and were gavaged with NP at a dose level of 0.02 μg/kg/day (NP-L-HSHFD), 0.2 μg/kg/day (NP-M-HSHFD) or 2 μg/kg/day (NP-H-HSHFD), respectively.

RESULT

On day 180, the rats in the groups treated with NP-M-HSHFD and NP-H-HSHFD showed significant increases in body weight (p < 0.05) in comparison with the C-ND group. Fast blood glucose (FBG) level in the NP-M-HSHFD and NP-H-HSHFD groups was higher than that in the C-ND group (F = 96.17, p < 0.001). The fast serum insulin (FINS) level of rats was lower in both the NP-M-HSHFD and NP-H-HSHFD groups compared with the C-ND group (F = 145.56, p < 0.001). Serum leptin (LEP) level in both the NP-M-HSHFD and NP-H-HSHFD groups was lower when compared with the C-ND group (F = 34.62, p < 0.001). The effect of NP at the dose level of 0.2 μg/kg/day on FBG, serum FINS and LEP levels in rats was greatest among the treatment groups (p < 0.05). Oral glucose tolerance test showed increased area under the curve (AUC) in treatment groups at week 12 (p < 0.05). A decrease of pancreatic islet numbers and size was exhibited in the pancreatic tissue of NP-M-HSHFD and NP-H-HSHFD treated rats compared with C-ND treated rats. Co-exposure to NP and HSHFD causes inflammatory changes histologically.

CONCLUSION

Chronic low-dose exposure to NP might induce impaired glucose tolerance, which further lead to insulin resistance, and pancreatic β cell insulin secretion deficiency, ultimately increase the risk of T2DM. Moreover, additive toxic effects of NP and HSHFD on pancreatic beta-cell function and glucose metabolism have been identified in rats as well.

Urinary Levels of 4-Nonylphenol and 4-t-Octylphenol in a Representative Sample of the Korean Adult Population

4-Nonylphenol (4-NP) and 4-t-octylphenol (4-t-OP) are xenoestrogen compounds to which humans are exposed via contaminated food, water, and air. This study assessed the body burden of 4-NP and 4-t-OP in Koreans aged 18-69 years using data from the Korean National Human Biomonitoring Survey conducted in 2009. Based on data from 1865 representative Koreans, 83.2% and 91.8% had urinary 4-NP and 4-t-OP concentrations >0.05 ng/mL (limit of detection). Of the Korean adult population, the geometric mean urinary concentrations of 4-NP and 4-t-OP were 3.70 ng/mL (95% confidence interval (CI) = 3.20-4.27) and 0.60 ng/mL (95% CI = 0.55-0.66), respectively. Urine 4-NP concentrations were significantly associated with place of residence and smoking status, whereas urine 4-t-OP concentrations were not correlated with any of the demographic factors. These findings suggest that most Koreans have detectable levels of 4-NP and 4-t-OP in their urine and that the body burden of 4-NP, but not 4-t-OP, varies according to some demographic factors.