Mechanisms of action of agrochemicals acting as endocrine disrupting chemicals

Hazard identification of endocrine-disrupting carcinogens (EDCs) in relation to cancers in humans

Endocrine disrupting chemicals or carcinogens have been known for decades for their endocrine signal disruption. Endocrine disrupting chemicals are a serious concern and they have been included in the top priority toxicants and persistent organic pollutants. Therefore, researchers have been working for a long time to understand their mechanisms of interaction in different human organs. Several reports are available about the carcinogen potential of these chemicals. The presented review is an endeavor to understand the hazard identification associated with endocrine disrupting carcinogens in relation to the human body. The paper discusses the major endocrine disrupting carcinogens and their potency for carcinogenesis. It discusses human exposure, route of entry, carcinogenicity and mechanisms. In addition, the paper discusses the research gaps and bottlenecks associated with the research. Moreover, it discusses the limitations associated with the analytical techniques for detection of endocrine disrupting carcinogens.

Glucocorticoid hormones in relation to environmental exposure to bisphenols and multiclass pesticides among middle aged-women: Results from hair analysis

Bisphenols and pesticides have been shown to alter circulating glucocorticoids levels in animals, but there is limited human data. Moreover, measurements from biological fluids may not be able to reflect long-term status of non-persistent pollutants and glucocorticoids due to the high variability in their levels. Using hair analysis, we examined the associations between glucocorticoid hormones and environmental exposure to multi-class organic pollutants among a healthy female population aged 25-45 years old. Concentrations of four glucocorticoids, four polychlorinated biphenyl congeners (PCBs), seven polybrominated diphenyl ether congeners (PBDEs), two bisphenols and 140 pesticides and their metabolites were measured in hair samples collected from 196 Chinese women living in urban areas. Due to the low detection frequency of some pollutants, associations were explored only on 54 pollutants, i.e. PCB 180, bisphenol A, bisphenol S and 51 pesticides and their metabolites. Using stability-based Lasso regression, there were associations of cortisol, tetrahydrocortisol, cortisone, and tetrahydrocortisone with 14, 10, 13 and 17 biomarkers of exposure to pollutants, respectively, with bisphenol S, p,p'-dichlorodiphenyldichloroethylene, diethyl phosphate, 3,5,6-trichloro-2-pyridinol, thiamethoxam, imidacloprid, fipronil, tebuconazole, trifluralin, pyraclostrobin and 1-(3,4-dichlorophenyl)-3-methylurea being associated with at least three of the four hormones. There were also associations between cortisone/cortisol molar ratio and pollutants, namely dimethyl phosphate, 3-methyl-4-nitrophenol, carbofuran, λ-cyhalothrin, permethrin, fipronil, flusilazole, prometryn and fenuron. Some of these relationships were confirmed by single-pollutant linear regression analyses. Overall, our results suggest that background level of exposure to bisphenols and currently used pesticides may interfere with the glucocorticoid homeostasis in healthy women.

From field to table: Ensuring food safety by reducing pesticide residues in food

The present review addresses the significance of lowering pesticide residue levels in food items because of their harmful impacts on human health, wildlife populations, and the environment. It draws attention to the possible health risks-acute and chronic poisoning, cancer, unfavorable effects on reproduction, and harm to the brain or immunological systems-that come with pesticide exposure. Numerous traditional and cutting-edge methods, such as washing, blanching, peeling, thermal treatments, alkaline electrolyzed water washing, cold plasma, ultrasonic cleaning, ozone treatment, and enzymatic treatment, have been proposed to reduce pesticide residues in food products. It highlights the necessity of a paradigm change in crop protection and agri-food production on a global scale. It offers opportunities to guarantee food safety through the mitigation of pesticide residues in food. The review concludes that the first step in reducing worries about the negative effects of pesticides is to implement regulatory measures to regulate their use. In order to lower the exposure to dietary pesticides, the present review also emphasizes the significance of precision agricultural practices and integrated pest management techniques. The advanced approaches covered in this review present viable options along with traditional methods and possess the potential to lower pesticide residues in food items without sacrificing quality. It can be concluded from the present review that a paradigm shift towards sustainable agriculture and food production is essential to minimize pesticide residues in food, safeguarding human health, wildlife populations, and the environment. Furthermore, there is a need to refine the conventional methods of pesticide removal from food items along with the development of modern techniques.

Histological evidence of hypothyroidism in mice chronically exposed to conventional farming

Worldwide, disorders of the thyroid gland are a growing concern; such can be caused by exposure to contaminants, including agrochemicals used in conventional agriculture, which act as endocrine disruptors. The purpose of this study is to evaluate whether or not exposure to an environment with conventional agriculture leads to thyroid disruption. Mus musculus were used as bioindicator species, captured in two sites: a farm where conventional agriculture is practiced, and a place without agriculture. Thyroid histomorphometric and morphologic data were analyzed. The impacts of the agricultural environment over the thyroid were revealed, as indications of hypothyroidism were observed in exposed mice: the area and volume of epithelial cells were much lower. Alterations in thyroid histomorphology were also observed: lower follicular sphericity, irregularly delimited epithelium and increased exfoliation into the colloid. These results highlight the need for transition from current conventional agricultural systems towards organic systems.

Pesticides exposure and compromised fitness in wild birds: Focusing on the reproductive endocrine disruption

Exposure of pesticides to wildlife species, especially on the aspect of endocrine disruption is of great concern. Wildlife species are more at risk to harmful exposures to the pesticides in their natural habitat through diet and several other means. Species at a higher tropic level in the food chain are more susceptible to the deleterious effects due to sequential biomagnifications of the pesticides/metabolites. Pesticides directly affect fitness of the species in the wild causing reproductive endocrine disruption impairing the hormones of the gonads and thyroid glands as reproduction is under the influence of cross regulations of these hormones. This review presents a comprehensive compilation of important literatures on the impact of the current use pesticides in disruption of both the hypothalamic-pituitary-gonadal and hypothalamic-pituitary-thyroid axes particularly in birds addressing impacts on the reproductive impairments and overall fitness. In addition to the epidemiological studies, laboratory investigations those provide supportive evidences of the probable mechanisms of disruption in the wild also have been incorporated in this review. To accurately predict the endocrine-disruption of the pesticides as well as to delineate the risk associated with potential cumulative effects, studies are to be more focused on the environmentally realistic exposure dose, mixture pesticide exposures and transgenerational effects. In addition, strategic screening/appropriate methodologies have to be developed to reveal the endocrine disruption potential of the contemporary use pesticides. Demand for adequate quantitative structure-activity relationships and insilico molecular docking studies for timely validation have been highlighted.

Toxicity effects of pesticides based on zebrafish (Danio rerio) models: Advances and perspectives

Pesticides inevitably enter aquatic environments, posing potential risks to organisms. The common aquatic model organism, zebrafish (Danio rerio), are widely used to evaluate the toxicity of pesticides. In this review, we searched the Web of Science database for articles published between 2012 and 2022, using the keywords "pesticide", "zebrafish", and "toxicity", retrieving 618 publications. Furthermore, we described the main pathways by which pesticides enter aquatic environments and the fate of their residues in these environments. We systematically reviewed the toxicity effects of pesticides on zebrafish, including developmental toxicity, endocrine-disrupting effects, reproductive toxicity, neurotoxicity, immunotoxicity, and genotoxicity. Importantly, we summarized the latest research progress on the toxicity mechanism of pesticides to zebrafish based on omics technologies, including transcriptomics, metabolomics, and microbiomics. Finally, we discussed future research prospects, focusing on the combined exposure of multiple pollutants including pesticides, the risk of multigenerational exposure to pesticides, and the chronic toxicity of aquatic nanopesticides. This review provides essential data support for ecological risk assessments of pesticides in aquatic environments, and has implications for water management in the context of pesticide pollution.

Thyroid Dysfunction Induced by Fungicide Famoxadone Exposure Contributes to Nonalcoholic Fatty Liver Disease in Male Mice: In Vivo, In Vitro, and In Silico Studies

Thyroid dysfunction has become a serious public health problem, which is considered a trigger of nonalcoholic fatty liver disease (NAFLD). Pesticide exposure could contribute to thyroid dysfunction and NAFLD, but the relationship between these factors remains unclear. In this study, the effects of subchronic famoxadone exposure on thyroid and liver at no observed adverse effect level (NOEL) related concentrations were investigated using in vivo, in vitro, and in silico models. Famoxadone caused hepatic steatosis, lipid metabolism disorder, and liver oxidative stress and induced NAFLD in male mice. The suppression of hepatic fatty acid β-oxidation was the key factor of NAFLD, which was highly associated with hypothalamic-pituitary-thyroid (HPT) axis hormones disorder. Famoxadone disrupted thyroid hormone biosynthesis by causing thyroid follicle aberrations and abnormal HPT axis-related gene expression. In vitro studies confirmed that famoxadone inhibited the transport of thyroxine (T4) into hepatocytes and the conversion of T4 to triiodothyronine (T3). In silico studies verified that famoxadone interfered with the binding of thyroid hormones to proteins mediating thyroid hormone transport, conversion, and activation. This study comprehensively reported the association between NAFLD and thyroid dysfunction caused by famoxadone, providing new perspectives for the health risk evaluation of pesticides with a similar structure in mammals.

Endocrine disrupting compounds in the baby's world - A harmful environment to the health of babies

Globally, there has been a significant increase in awareness of the adverse effects of chemicals with known or suspected endocrine-acting properties on human health. Human exposure to endocrine disrupting compounds (EDCs) mainly occurs by ingestion and to some extent by inhalation and dermal uptake. Although it is difficult to assess the full impact of human exposure to EDCs, it is well known that timing of exposure is of importance and therefore infants are more vulnerable to EDCs and are at greater risk compared to adults. In this regard, infant safety and assessment of associations between prenatal exposure to EDCs and growth during infancy and childhood has been received considerable attention in the last years. Hence, the purpose of this review is to provide a current update on the evidence from biomonitoring studies on the exposure of infants to EDCs and a comprehensive view of the uptake, the mechanisms of action and biotransformation in baby/human body. Analytical methods used and concentration levels of EDCs in different biological matrices (e.g., placenta, cord plasma, amniotic fluid, breast milk, urine, and blood of pregnant women) are also discussed. Finally, key issues and recommendations were provided to avoid hazardous exposure to these chemicals, taking into account family and lifestyle factors related to this exposure.

Cumulative Exposure to Phthalates and Their Alternatives and Associated Female Reproductive Health: Body Burdens, Adverse Outcomes, and Underlying Mechanisms

The global birth rate has recently shown a decreasing trend, and exposure to environmental pollutants has been identified as a potential factor affecting female reproductive health. Phthalates have been widely used as plasticizers in plastic containers, children's toys, and medical devices, and their ubiquitous presence and endocrine-disrupting potential have already raised particular concerns. Phthalate exposure has been linked to various adverse health outcomes, including reproductive diseases. Given that many phthalates are gradually being banned, a growing number of phthalate alternatives are becoming popular, such as di(isononyl) cyclohexane-1,2-dicarboxylate (DINCH), di(2-ethylhexyl) adipate (DEHA), and di(2-ethylhexyl) terephthalate (DEHTP), and they are beginning to have a wide range of environmental effects. Studies have shown that many phthalate alternatives may disrupt female reproductive function by altering the estrous cycle, causing ovarian follicular atresia, and prolonging the gestational cycle, which raises growing concerns about their potential health risks. Herein, we summarize the effects of phthalates and their common alternatives in different female models, the exposure levels that influence the reproductive system, and the effects on female reproductive impairment, adverse pregnancy outcomes, and offspring development. Additionally, we scrutinize the effects of phthalates and their alternatives on hormone signaling, oxidative stress, and intracellular signaling to explore the underlying mechanisms of action on female reproductive health, because these chemicals may affect reproductive tissues directly or indirectly through endocrine disruption. Given the declining global trends of female reproductive capacity and the potential ability of phthalates and their alternatives to negatively impact female reproductive health, a more comprehensive study is needed to understand their effects on the human body and their underlying mechanisms. These findings may have an important role in improving female reproductive health and in turn decreasing the number of complications during pregnancy.

Applications of nanotechnology to combat the problems associated with modern food

Currently, modern lifestyle diseases (LSD) such as cancer, diabetes, hypertension, cardiovascular and thyroid disease are commonly seen among people of different age groups. One of the root causes of this LSD is the type of food that we are eating. Staple crops like rice, sugarcane, vegetables and wheat are grown with the application of agrochemicals (e.g., glyphosate), traces of which are found in our food; after that, it gets ultra-processed in factories; e.g., chips and snacks are fried using saturated fats (trans fat); sugar and wheat (derivatives bread, buns, cookies) are processed using toxic chemicals (bleaching agents). As a result, the nutritional value of food is compromised due to low dietary fiber content and synthetic additives - e.g., sucralose (artificial sweetener) - which promotes inflammation and weakens our immune system, causing our body to become sensitive to microbial infection and many other LSDs. To strengthen the immune system, people start taking synthetically prepared supplements and drugs for a prolonged time, which further deteriorates the body organs and their normal function; e.g., prolonged medication for hypothyroidism poses a risk of heart attack and joint pain. Nanotechnology solves the above problems in the food, nutraceuticals and agriculture sectors. Nanotechnology-based naturally processed products such as nano-nutraceuticals, nanofood, nanofertilizers and nanopesticides will benefit our health. They possess desirable properties such as high bioavailability, targeted delivery, least processing and sustained release. With the help of nanotechnology, we can get nutritional and agrochemical-free food. © 2022 Society of Chemical Industry.

Pesticide drift mitigation measures appear to reduce contamination of non-agricultural areas, but hazards to humans and the environment remain

Pesticide drift onto non-agricultural land is a common problem in intensively farmed regions, and national action plans have been established across Europe to prevent it. Here, we analyzed official data on pesticide residues in grass samples collected over six years to determine whether implemented measures to reduce pesticide drift were effective. We used 306 samples collected between 2014 and 2020 on non-agricultural land in one of the most intensively managed apple and wine growing regions in Europe, the Autonomous Province of Bolzano-South Tyrol, Italy. Samples were analyzed for up to 314 substances by gas chromatography and mass spectrometry. Percentage of sites with multiple pesticides and number of pesticides decreased between 2014 and 2020. Fungicides were most often detected, with fluazinam found on 74 % and captan on 60 % of the contaminated sites (53 sites out of a total of 88 sites were contaminated). The most frequently found insecticide, phosmet, was detected in 49 % of the contaminated sites. Only one herbicide, oxadiazon, was detected in <1 % of the sites; glyphosate was not analyzed. The percentage of residues with human hazard properties increased significantly across years regarding reproductive toxicity (from 21 % of the detected substances in 2014 to 88 % in 2020) and specific target organ toxicity (0 % in 2014 to 21 % in 2020). Percentages of substances associated with endocrine-disruption (89 % of substances across years) or carcinogenic properties (45 % of substances across years) remained constant. The percentage of sites where concentrations in grass samples exceeded the surrogate maximum residue levels (MRLs) for lettuce also remained constant. Potential ecotoxicological hazards of detected residues regarding acute contact toxicity to honeybees remained high over the study years, while the acute and chronic toxicity to earthworms decreased. Our results suggest that while drift mitigation measures contributed some reduction in pesticide contamination, they were not sufficient to eliminate substantial risks to human health and the environment in nontarget areas.

Toxicogenomics Data for Chemical Safety Assessment and Development of New Approach Methodologies: An Adverse Outcome Pathway-Based Approach

Mechanistic toxicology provides a powerful approach to inform on the safety of chemicals and the development of safe-by-design compounds. Although toxicogenomics supports mechanistic evaluation of chemical exposures, its implementation into the regulatory framework is hindered by uncertainties in the analysis and interpretation of such data. The use of mechanistic evidence through the adverse outcome pathway (AOP) concept is promoted for the development of new approach methodologies (NAMs) that can reduce animal experimentation. However, to unleash the full potential of AOPs and build confidence into toxicogenomics, robust associations between AOPs and patterns of molecular alteration need to be established. Systematic curation of molecular events to AOPs will create the much-needed link between toxicogenomics and systemic mechanisms depicted by the AOPs. This, in turn, will introduce novel ways of benefitting from the AOPs, including predictive models and targeted assays, while also reducing the need for multiple testing strategies. Hence, a multi-step strategy to annotate AOPs is developed, and the resulting associations are applied to successfully highlight relevant adverse outcomes for chemical exposures with strong in vitro and in vivo convergence, supporting chemical grouping and other data-driven approaches. Finally, a panel of AOP-derived in vitro biomarkers for pulmonary fibrosis (PF) is identified and experimentally validated.

Reproductive damage and compensation of wild earthworm Metaphire californica from contaminated fields with long-term heavy metal exposure

Reproduction is a significant biological process for organisms responding to environmental stresses, however, little is known about the reproductive strategies of invertebrates under long-term exposure to contaminations. In this study, earthworm Metaphire californica (Kinberg, 1867) from contaminated fields with an increased metal gradient were collected to investigate their reproductive responses. The results showed heavy metals (Cd, Cu, Zn, and Pb) induced histological damage to earthworms' seminal vesicles, including tissue disorders and cavities, and decreases in mature spermatozoa. Sperm morphology analysis indicated deformity rates were up to13.2% (e.g. head swollen or missing) for worms from the most contaminated site, which coincided with DNA damages. Furthermore, the computer-assisted sperm analysis (CASA) system was employed for the evaluation of sperm kinetic traits. Results suggested earthworms exposed to higher contamination showed a lower sperm viability rate but faster sperm velocity after re-exposure with Cd solution (like the curvilinear velocity and straight-line velocity paraments) compared with those from relatively clean sites. The activities of lactate dehydrogenase and sorbitol dehydrogenase showed the highest 32.5% and 12.5% up-regulation respectively with the increased metal gradient. In conclusion, this study elucidated the earthworm reproductive toxicity, underlying reproductive compensation, metal stress-induced damages, and adaptive responses caused by heavy metal exposure, while also providing the possibility of sperm trait analysis (CASA) for related earthworm toxicological studies.

Diethyl phosphate disrupts hypothalamus-pituitary-adrenal axis endocrine hormones via nuclear receptors GR and Nur77: Integration of evidences from in vivo, in vitro and in silico approaches

Plenty of population epidemiology and cohort studies have found dialkyl phosphates (DAPs) in the urine were related to endocrine hormone disorders. However, we did not know whether these effects were caused by parent organophosphorus pesticides (OPs) or metabolite DAPs, especially the non-specific metabolite diethyl phosphate (DEP), which was the metabolic end product of most widely used diethyl OPs. In this study, animal experiments (in vivo), cell experiments (in vitro), small molecule-protein binding interaction experiments and computer molecular simulations (in silico) were used to explore the disturbing effects and molecular mechanisms of DEP on the hypothalamic-pituitary-adrenal (HPA) axis endocrine hormones. The animal experiments showed that chronic DEP exposure significantly disturbed the serum contents of HPA axis hormones in adult male rats. The target genes of glucocorticoid receptor (GR) in rat liver, including 11β-hsd1 and Pepck1 and PEPCK protein expressions, were down-regulated. Moreover, the gluconeogenic abilities of rats were impaired. However, it did not affect the expression of GR in the rat hypothalamus. These results indicated that the physiological functions of glucocorticoids and GR were damaged. Furthermore, spectroscopy experiments, cell experiments, molecular docking and molecular dynamics simulations also suggested that DEP can bind to nuclear receptors GR and Nur77, affecting their transcription factor functions, and the transcriptional expression levels of their downstream target genes were reduced. The biosynthesis and secretion of adrenocorticotropic hormone and glucocorticoids were blocked. Therefore, DEP can inhibit the production and physiological functions of HPA axis endocrine hormones by disrupting these related proteins and antagonizing nuclear receptors. These results were considered to provide a theoretical basis for strictly controlling the residue limits of OPs and their metabolites in foods, agricultural products and the environment. They also revealed new targets for evaluating the toxicities and risks of pesticide metabolites.

Pesticide impacts on avian species with special reference to farmland birds: a review

For decades, we have observed a major biodiversity crisis impacting all taxa. Avian species have been particularly well monitored over the long term, documenting their declines. In particular, farmland birds are decreasing worldwide, but the contribution of pesticides to their decline remains controversial. Most studies addressing the effects of agrochemicals are limited to their assessment under controlled laboratory conditions, the determination of lethal dose 50 (LD₅₀) values and testing in a few species, most belonging to Galliformes. They often ignore the high interspecies variability in sensitivity, delayed sublethal effects on the physiology, behaviour and life-history traits of individuals and their consequences at the population and community levels. Most importantly, they have entirely neglected to test for the multiple exposure pathways to which individuals are subjected in the field (cocktail effects). The present review aims to provide a comprehensive overview for ecologists, evolutionary ecologists and conservationists. We aimed to compile the literature on the effects of pesticides on bird physiology, behaviour and life-history traits, collecting evidence from model and wild species and from field and lab experiments to highlight the gaps that remain to be filled. We show how subtle nonlethal exposure might be pernicious, with major consequences for bird populations and communities. We finally propose several prospective guidelines for future studies that may be considered to meet urgent needs.

Binding and Activation of Estrogen-Related Receptor γ: A Novel Molecular Mechanism for the Estrogenic Disruption Effects of DDT and Its Metabolites

DDT and its metabolites (DDTs) can induce estrogenic effects. Previous mechanistic investigations mainly concentrated on activating the genomic transcription of estrogen receptor (ER) pathways. Here, we identified whether estrogen-related receptor γ (ERRγ), an orphan nuclear receptor, is a potential target of DDTs by receptor binding, transcriptional activity, and receptor-mediated pathway assays. Fluorescence polarization-based binding assays showed that all eight DDTs bound to ERRγ directly, with K_d values ranging from 0.73-168.82 μM. Among them, 2,2-bis(4-chlorophenyl)ethanol (4,4'-DDOH) exhibited the highest binding affinity, which was 2.5-fold stronger than GSK4716, a well-known ERRγ agonist. Eight DDTs exhibited agonistic activity toward the ERRγ pathway, with 4,4'-DDOH showing the strongest potency. In silico studies revealed that DDTs tended to bind with ERRγ in the agonistic conformation. Using a SKBR3 breast cancer cell model, we further found that nanomolar or micromolar levels of DDTs significantly activated the ERRγ pathway in cells and induced cell proliferation through the ERRγ-modulated cell cycle. These results indicated that the binding and activation of DDTs to ERRγ might serve as molecular initiating events for subsequent ERRγ-mediated signaling pathways and adverse outcomes. Overall, our results demonstrated that ERRγ might be a crucial pathway involved in the estrogenic disruption effects of DDTs.

A systematic review and meta-analysis of the impacts of glyphosate on the reproductive hormones

Worldwide use of glyphosate is constantly increasing and its residues are detected in drinking water, agriculture, and food products. There are controversial data regarding the potential reproductive adverse effects of glyphosate herbicide. Therefore, we conducted a systematic review and meta-analysis on the studies in which the alteration of at least one sexual hormone including testosterone, luteinizing hormone (LH), follicle-stimulating hormone (FSH), and estradiol was reported as a measured outcome in rats. In November 2020, 284 articles were screened, of which eight were eligible for the meta-analysis. An overall considerable effect of glyphosate exposure was found on decreasing of testosterone (7 studies, WMD = - 1.48 ng/mL; 95% CI, - 2.34 to - 0.61; P = 0.001), LH (3 studies, WMD = - 2.03 mIu/mL; 95% CI, - 3.34 to - 0.71; P = 0.003), and FSH (3 studies, WMD = - 2.28 mIu/mL; 95% CI, - 5.12 to 0.55; P = 0.115). According to our results, glyphosate intake could have major effects on the health of reproductive system. Consequently, strict monitoring of the residual glyphosate content in the drinking water, agricultural crops, and food products is necessary.

PPARβ mediates mangiferin-induced neuronal differentiation of neural stem cells through DNA demethylation

Adult hippocampal neurogenesis (AHN) is heavily implicated in the pathogenesis of various neuropsychiatric disorders. The mangiferin (MGF), a bioactive compound of the mango, reportedly produces biological effects on a variety of neuropsychiatric disorders. However, the function and underlying mechanisms of MGF in regulating hippocampal neurogenesis remain unknown. Here we discovered that the transcriptome and methylome of MGF-induced neural stem cells (NSCs) are distinct from the control. RNA-seq analysis revealed that the diferentially expressed genes (DEGs) were signifcantly enriched in the PPARs. Furthermore, we found that MGF enhanced neuronal differentiation and proliferation of neural stem cells (NSCs) via PPARβ but not PPARα and PPARγ. The combination of WGBS and RNA-seq analysis showed that the expression of some neurogenesis genes was negatively correlated with the DNA methylation level generally. We further found that PPARβ increased demethylation of Mash1 promoter by modulating the expressions of active and passive DNA demethylation enzymes in MGF-treated NSCs. Importantly, genetic deficiency of PPARβ decreased hippocampal neurogenesis in the adult mice, whereas the defective neurogenesis was notably rescued by Mash1 overexpression. Our findings uncover a model that PPARβ-mediated DNA demethylation of Mash1 contributes to MGF-induced neuronal genesis, and advance the concept that targeting PPARβ-TET1/DNMT3a-Mash1 axis regulation of neurogenesis might serve as a novel neurotherapeutic strategy.

Identifying potential thyroid hormone disrupting effects among diphenyl ether structure pesticides and their metabolites in silico

The environmental and dietary pesticide exposures can cause thyroid hormones (THs) disorders, which are associated with the high incidence of thyroid diseases worldwide. The structures of diphenyl ether pesticides and their metabolites are very similar to the structure of THs. Based on this, in silico molecular simulation approaches were used to predict, screen, evaluate and identify the binding interactions of 98 diphenyl ether structure pesticides and their metabolites (DEPMs) with 10 THs related proteins in the study. The research results indicated that these DEPMs such as fluoroglycofen (FOG), rafoxanide, diclofop, ethoxyfen and difenopenten were considered to have the greater potentials to interfere with the related proteins of THs biosynthesis, blood transport, receptor binding and metabolism. And FOG can interact with thyroid hormone receptor beta (TRβ) to form non-bond interactions. Furthermore, the results of molecular dynamics simulations showed that there were strong and stable interactions between FOG and TRβ. These results suggested that the herbicide FOG was likely to disturb THs nuclear receptor. And benzene rings and hydrophobic groups might be the characteristic chemical functional groups for DEPMs to disrupt TRβ. The relevant results of this study can be used to provide references for environmental toxicology evaluation, food safety risk assessment, and formulation and revision of pesticides and their metabolites residue limits in agricultural products and food.

Pesticides: formulants, distribution pathways and effects on human health - a review

Pesticides are commonly used in agriculture to enhance crop production and control pests. Therefore, pesticide residues can persist in the environment and agricultural crops. Although modern formulations are relatively safe to non-target species, numerous theoretical and experimental data demonstrate that pesticide residues can produce long-term negative effects on the health of humans and animals and stability of ecosystems. Of particular interest are molecular mechanisms that mediate the start of a cascade of adverse effects. This is a review of the latest literature data on the effects and consequences of contamination of agricultural crops by pesticide residues. In addition, we address the issue of implicit risks associated with pesticide formulations. The effects of pesticides are considered in the context of the Adverse Outcome Pathway concept.

A computational insight into endocrine disruption by polychlorinated biphenyls via non-covalent interactions with human nuclear receptors

Production of polychlorinated biphenyls (PCBs) was banned a long time ago because of their harmful health effects but humans continue to be exposed to residual PCBs in the environment. In this study, the susceptibility of human nuclear receptors to binding by PCBs was investigated using molecular docking simulation. Findings revealed that PCBs belonging to ortho-substituted, mono-ortho-substituted and non-ortho-substituted congeners could bind to agonistic conformations of androgen (AR), estrogen (ER α and ER β), glucocorticoid (GR) and thyroid hormone (TR α and TR β) receptors as well as antagonistic conformation of androgen receptor (AR an) but only ortho-substituted and mono-ortho-substituted PCBs could bind to estrogen receptors in their antagonistic conformations (ER α an and ER β an). Further molecular docking analyses showed that PCBs mimic the modes of interaction observed for the co-crystallized ligands in the crystal structures of the affected receptors, utilizing 81%, 83%, 78%, 60%, 75%, 60%, 86%, 100% and 75% of the amino acid residues utilized by the co-crystallized ligands for binding in AR, AR an, ER α, ER α an, ER β, ER β an, GR, TR α and TR β respectively. This computational study suggests that PCBs may cause endocrine disruption via formation of non-covalent interactions with androgen, estrogen, glucocorticoid and thyroid hormone receptors.

Differential Disrupting Effects of Prolonged Low-Dose Exposure to Dichlorodiphenyltrichloroethane on Androgen and Estrogen Production in Males

Dichlorodiphenyltrichloroethane (DDT) is the most widespread, persistent pollutant and endocrine disruptor on the planet. Although DDT has been found to block androgen receptors, the effects of its low-dose exposure in different periods of ontogeny on the male reproductive system remain unclear. We evaluate sex steroid hormone production in the pubertal period and after maturation in male Wistar rats exposed to low doses of o,p'-DDT, either during prenatal and postnatal development or postnatal development alone. Prenatally and postnatally exposed rats exhibit lower testosterone production and increased estradiol and estriol serum levels after maturation, associated with the delayed growth of gonads. Postnatally exposed rats demonstrate accelerated growth of gonads and higher testosterone production in the pubertal period. In contrast to the previous group, they do not present raised estradiol production. All of the exposed animals exhibit a reduced conversion of progesterone to 17OH-progesterone after sexual maturation, which indicates putative attenuation of sex steroid production. Thus, the study reveals age-dependent outcomes of low-dose exposure to DDT. Prenatal onset of exposure results in the later onset of androgen production and the enhanced conversion of androgens to estrogens after puberty, while postnatal exposure induces the earlier onset of androgen secretion.

Birds feeding on tebuconazole treated seeds have reduced breeding output

Drilled seeds are an important food resource for many farmland birds but may pose a serious risk when treated with pesticides. Most compounds currently used as seed treatment in the EU have low acute toxicity but may still affect birds in a sub-chronic or chronic way, especially considering that the sowing season lasts several weeks or months, resulting in a long exposure period for birds. Tebuconazole is a triazole fungicide widely used in agriculture but its toxicity to birds remains largely unknown. Our aim was to test if a realistic scenario of exposure to tebuconazole treated seeds affected the survival and subsequent reproduction of the red-legged partridge (Alectoris rufa). We fed captive partridges with wheat seeds treated with 0%, 20% or 100% of tebuconazole application rate during 25 days in late winter (i.e. tebuconazole dietary doses were approximately 0.2 and 1.1 mg/kg bw/day). We studied treatment effects on the physiology (i.e. body weight, biochemistry, immunology, oxidative stress, coloration) and reproduction of partridges. Exposed birds did not reduce food consumption but presented reduced plasmatic concentrations of lipids (triglycerides at both exposure doses, cholesterol at high dose) and proteins (high dose). The coloration of the eye ring was also reduced in the low dose group. Exposure ended 60 days before the first egg was laid, but still affected reproductive output: hatching rate was reduced by 23% and brood size was 1.5 times smaller in the high dose group compared with controls. No significant reproductive effects were found in the low dose group. Our results point to the need to study the potential endocrine disruption mechanism of this fungicide with lagged effects on reproduction. Risk assessments for tebuconazole use as seed treatment should be revised in light of these reported effects on bird reproduction.

Agrochemicals in freshwater systems and their potential as endocrine disrupting chemicals: A South African context

South Africa is the largest agrochemical user in sub-Saharan Africa, with over 3000 registered pesticide products. Although they reduce crop losses, these chemicals reach non-target aquatic environments via leaching, spray drift or run-off. In this review, attention is paid to legacy and current-use pesticides reported in literature for the freshwater environment of South Africa and to the extent these are linked to endocrine disruption. Although banned, residues of many legacy organochlorine pesticides (endosulfan and dichlorodiphenyltrichloroethane (DDT)) are still detected in South African watercourses and wildlife. Several current-use pesticides (triazine herbicides, glyphosate-based herbicides, 2,4-dichlorophenoxyacetic acid (2,4-D) and chlorpyrifos) have also been reported. Agrochemicals can interfere with normal hormone function of non-target organism leading to various endocrine disrupting (ED) effects: intersex, reduced spermatogenesis, asymmetric urogenital papillae, testicular lesions and infertile eggs. Although studies investigating the occurrence of agrochemicals and/or ED effects in freshwater aquatic environments in South Africa have increased, few studies determined both the levels of agricultural pesticides present and associated ED effects. The majority of studies conducted are either laboratory-based employing in vitro or in vivo bioassays to determine ED effects of agrochemicals or studies that investigate environmental concentrations of pesticides. However, a combined approach of bioassays and chemical screening will provide a more comprehensive overview of agrochemical pollution of water systems in South Africa and the risks associated with long-term chronic exposure.

Oxidative Stress in NAFLD: Role of Nutrients and Food Contaminants

Non-alcoholic fatty liver disease (NAFLD) is often the hepatic expression of metabolic syndrome and its comorbidities that comprise, among others, obesity and insulin-resistance. NAFLD involves a large spectrum of clinical conditions. These range from steatosis, a benign liver disorder characterized by the accumulation of fat in hepatocytes, to non-alcoholic steatohepatitis (NASH), which is characterized by inflammation, hepatocyte damage, and liver fibrosis. NASH can further progress to cirrhosis and hepatocellular carcinoma. The etiology of NAFLD involves both genetic and environmental factors, including an unhealthy lifestyle. Of note, unhealthy eating is clearly associated with NAFLD development and progression to NASH. Both macronutrients (sugars, lipids, proteins) and micronutrients (vitamins, phytoingredients, antioxidants) affect NAFLD pathogenesis. Furthermore, some evidence indicates disruption of metabolic homeostasis by food contaminants, some of which are risk factor candidates in NAFLD. At the molecular level, several models have been proposed for the pathogenesis of NAFLD. Most importantly, oxidative stress and mitochondrial damage have been reported to be causative in NAFLD initiation and progression. The aim of this review is to provide an overview of the contribution of nutrients and food contaminants, especially pesticides, to oxidative stress and how they may influence NAFLD pathogenesis.

Ultrastructural Mechanisms of Impaired Aldosterone Synthesis in Rats Exposed to DDT during Prenatal and Postnatal Development

The study is aimed at elucidation of ultrastructural mechanisms underlying impaired aldosterone synthesis by glomerulosa cells in Wistar rats exposed to low doses of endocrine disrupter DDT during prenatal and postnatal development. Analysis of rat zona glomerulosa histology and function during the pubertal and postpubertal periods showed that exposure to endocrine disrupter DDT disturbs its development and reduced the production of aldosterone. Electron microscopy showed that changes in the aldosterone synthesis are related to impaired reorganization of the mitochondrial apparatus, one of the leading factors in the regulation of steroidogenesis, in glomerulosa cells in DDT-exposed rats during puberty.

Sex steroids and autoimmune rheumatic diseases: state of the art

In autoimmune rheumatic diseases, oestrogens can stimulate certain immune responses (including effects on B cells and innate immunity), but can also have dose-related anti-inflammatory effects on T cells, macrophages and other immune cells. By contrast, androgens and progesterone have predominantly immunosuppressive and anti-inflammatory effects. Hormone replacement therapies and oral contraception (and also pregnancy) enhance or decrease the severity of autoimmune rheumatic diseases at a genetic or epigenetic level. Serum androgen concentrations are often low in men and in women with autoimmune rheumatic diseases, suggesting that androgen-like compounds might be a promising therapeutic approach. However, androgen-to-oestrogen conversion (known as intracrinology) is enhanced in inflamed tissues, such as those present in patients with autoimmune rheumatic diseases. In addition, it is becoming evident that the gut microbiota differs between the sexes (known as the microgenderome) and leads to sex-dependent genetic and epigenetic changes in gastrointestinal inflammation, systemic immunity and, potentially, susceptibility to autoimmune or inflammatory rheumatic diseases. Future clinical research needs to focus on the therapeutic use of androgens and progestins or their downstream signalling cascades and on new oestrogenic compounds such as tissue-selective oestrogen complex to modulate altered immune responses.

The EDCMET Project: Metabolic Effects of Endocrine Disruptors

Endocrine disruptors (EDs) are defined as chemicals that mimic, block, or interfere with hormones in the body's endocrine systems and have been associated with a diverse array of health issues. The concept of endocrine disruption has recently been extended to metabolic alterations that may result in diseases, such as obesity, diabetes, and fatty liver disease, and constitute an increasing health concern worldwide. However, while epidemiological and experimental data on the close association of EDs and adverse metabolic effects are mounting, predictive methods and models to evaluate the detailed mechanisms and pathways behind these observed effects are lacking, thus restricting the regulatory risk assessment of EDs. The EDCMET (Metabolic effects of Endocrine Disrupting Chemicals: novel testing METhods and adverse outcome pathways) project brings together systems toxicologists; experimental biologists with a thorough understanding of the molecular mechanisms of metabolic disease and comprehensive in vitro and in vivo methodological skills; and, ultimately, epidemiologists linking environmental exposure to adverse metabolic outcomes. During its 5-year journey, EDCMET aims to identify novel ED mechanisms of action, to generate (pre)validated test methods to assess the metabolic effects of Eds, and to predict emergent adverse biological phenotypes by following the adverse outcome pathway (AOP) paradigm.