Individual and combined developmental toxicity assessment of bisphenol A and genistein using the embryonic stem cell test in vitro

BPA Exposure Affects Mouse Gastruloids Axial Elongation by Perturbing the Wnt/β-Catenin Pathway

Mammalian embryos are very vulnerable to environmental toxicants (ETs) exposure. Bisphenol A (BPA), one of the most diffused ETs, exerts endocrine-disrupting effects through estro-gen-mimicking and hormone-like properties, with detrimental health effects, including on reproduction. However, its impact during the peri-implantation stages is still unclear. This study, using gastruloids as a 3D stem cell-based in vitro model of embryonic development, showed that BPA exposure arrests their axial elongation when present during the Wnt/β-catenin pathway activation period by β-catenin protein reduction. Gastruloid reshaping might have been impeded by the downregulation of Snail, Slug and Twist, known to suppress E-cadherin expression and to activate the N-cadherin gene, and by the low expression of the N-cadherin protein. Also, the lack of gastruloids elongation might be related to altered exit of BPA-exposed cells from the pluripotency condition and their following differentiation. In conclusion, here we show that the inhibition of gastruloids' axial elongation by BPA might be the result of the concomitant Wnt/β-catenin perturbation, reduced N-cadherin expression and Oct4, T/Bra and Cdx2 altered patter expression, which all together concur in the impaired development of mouse gastruloids.

Public perception on human exposure risk: A case study on endocrine disrupting compounds in the environment

Humans are exposed to environmental risks owing to the broad usage of endocrine disrupting compounds (EDCs). However, the subjective evaluation of risk levels and characteristics, as well as the variation in risk processing, have not been thoroughly examined. The objective was to understand the public's perception of the risk associated with human exposure to environmental EDCs and identify any variations in risk perception. In this pioneering study conducted within the distinctive social and cultural context of Malaysia, a developing nation, a quantitative analysis approach was employed to assess the subjective evaluation of risk levels and characteristics among the public while developing a risk perception model. Data gathered from surveys and questionnaires were analyzed to gather information on the public's perception of environmental and health issues pertaining to pesticides, hormones, plastics, medicines, and cosmetics. The analysis revealed that the majority of the public assessed the level of human exposure to environmental risks based on experiential processing, which was influenced by cognitive and affective variables. Interestingly, a higher proportion of individuals in the community had a low risk perception of environmental EDCs, surpassing the overall risk perception by 19.3%. Furthermore, the public showed significant awareness of environmental and health issues related to pesticides, hormones, and plastics but had a lesser inclination to acknowledge the vulnerability of humans to risks associated with medicines and cosmetics. These findings suggest that the public is likely to be exposed to environmental EDCs based on their current perceived risks, and that sociopsychological factors play a significant role in shaping perceptions and judgments. This understanding can inform the development of targeted risk management strategies and interventions to mitigate the potential harm caused by environmental EDCs.

The Mechanism of Houttuynia cordata Embryotoxicity Was Explored in Combination with an Experimental Model and Network Pharmacology

Houttuynia cordata (H. cordata) is the most common herb as a food and traditional Chinese medicine. Currently, studies on its toxicity have mainly focused on hepatotoxicity. However, its potential embryotoxicity by long-term exposure is often overlooked. Objective: To investigate the effects of H. cordata on embryonic development and its toxicity mechanism by combining network pharmacology, molecular docking, and in vitro experimental methods. Methods: The effects of H. cordata on embryos were evaluated. Zebrafish embryos and embryoid bodies were administered to observe the effects of H. cordata on embryonic development. Based on network pharmacological analysis, it was found that the main active agents producing toxicity in H. cordata were oleanolic acid, lignan, and aristolactam AII. H. cordata can affect PI3K-Akt, MAPK, and Ras signaling pathways by regulating targets, such as AKT1, EGFR, CASP3, and IGF-1. RT-PCR and immunohistochemistry results showed that the expression of AKT1 and PI3K in the embryoid body was significantly reduced after drug administration (p < 0.05). Conclusions: The results of network pharmacology and in vitro experiments suggest that H. cordata may affect embryonic development by influencing the PI3K-Akt signaling pathway.

The DevTox Germ Layer Reporter Platform: An Assay Adaptation of the Human Pluripotent Stem Cell Test

Environmental chemical exposures are a contributing factor to birth defects affecting infant morbidity and mortality. The USA EPA is committed to developing new approach methods (NAMs) to detect chemical risks to susceptible populations, including pregnant women. NAM-based coverage for cellular mechanisms associated with early human development could enhance identification of potential developmental toxicants (DevTox) for new and existing data-poor chemicals. The human pluripotent stem cell test (hPST) is an in vitro test method for rapidly identifying potential human developmental toxicants that employs directed differentiation of embryonic stem cells to measure reductions in SOX17 biomarker expression and nuclear localization. The objective of this study was to expand on the hPST principles to develop a model platform (DevTox GLR) that utilizes the transgenic RUES2-GLR cell line expressing fluorescent reporter fusion protein biomarkers for SOX17 (endoderm marker), BRA (mesoderm marker), and SOX2 (ectoderm and pluripotency marker). Initial assay adaption to definitive endoderm (DevTox GLR-Endo) was performed to emulate the hPST SOX17 endpoint and enable comparative evaluation of concordant chemical effects. Assay duration was reduced to two days and screening throughput scaled to 384-well format for enhanced speed and efficiency. Assay performance for 66 chemicals derived from reference and training set data resulted in a balanced accuracy of 72% (79% sensitivity and 65% specificity). The DevTox GLR-Endo assay demonstrates successful adaptation of the hPST concept with increased throughput, shorter assay duration, and minimal endpoint processing. The DevTox GLR model platform expands the in vitro NAM toolbox to rapidly identify potential developmental hazards and mechanistically characterize toxicant effects on pathways and processes associated with early human development.

Chemical Exposure-Induced Developmental Neurotoxicity in Head-Regenerating Schmidtea Mediterranea

The growing number of commercially-used chemicals that are under-evaluated for developmental neurotoxicity (DNT) combined with the difficulty in describing the etiology of exposure-related neurodevelopmental toxicity has created a reticent threat to human health. Current means of screening chemicals for DNT are limited to expensive, time-consuming, and labor-intensive traditional laboratory animal models. In this study, we hypothesize that exposed head regenerating planarian flatworms can effectively and efficiently categorize DNT in known developmental neurotoxins (ethanol and bisphenol A (BPA)). Planarian flatworms are an established alternative animal model for neurodevelopmental studies and have remarkable regenerative abilities allowing neurodevelopment to be induced via head resection. Here, we observed changes in photophobic behavior and central nervous system (CNS) morphology to evaluate the impact of exposure to low concentrations of ethanol, BPA, and BPA industry alternatives bisphenol F (BPF), and bisguaiacol (BG) on neurodevelopment. Our studies show that exposure to 1% v/v ethanol during regeneration induces a recoverable 48-hour delay in the development of proper CNS integrity, which aligns with behavioral assessments of cognitive ability. Exposure to BPA and its alternatives induced deviations to neurodevelopment in a range of severities, distinguished by suppressions, delays, or a combination of the two. These results suggest that quick and inexpensive behavioral assessments are a viable surrogate for tedious and costly immunostaining studies, equipping more utility and resolution to the planarian model for neurodevelopmental toxicity in the future of mass chemical screening. These studies demonstrate that behavioral phenotypes observed following chemical exposure are classifiable and also temporally correlated to the anatomical development of the central nervous system in planaria. This will facilitate and accelerate toxicological screening assays with this alternative animal model.

The Variations of Metabolic Detoxification Enzymes Lead to Recurrent Miscarriage and Their Diagnosis Strategy

Spontaneous abortion has been a common obstetrical and gynecological disease, which occurs in 10-15% of all pregnancies. Recurrent miscarriage (RM) refers to the occurrence of three or more times abortions with the same partner. It is generally believed that environmental pollution associated with economic development may cause infertility and RM. When xenobiotics from the environment enter the body, they must be cleared from the body by various metabolic enzymes in the body. The absence or variation of these enzymes may be the genetic basis of RM caused by environmental pollution. The variation of metabolic detoxification enzyme can directly affect the removal of harmful substances from internal and external sources. Therefore, the determination of metabolic enzyme activity may become an important factor in the diagnosis of RM etiology and seeking methods to improve the detoxification ability has a great significance for the treatment of RM.

Tap water contamination: Multiclass endocrine disrupting compounds in different housing types in an urban settlement

Contamination of endocrine disrupting compounds (EDCs) in tap water is an emerging global issue, and there are abundant influencing factors that have an ambivalent effect on their transportation and fate. Different housing types vary in terms of water distribution system operation and design, water consumption choices, and other hydraulic factors, which potentially affect the dynamics, loadings, and partitioning of pollutants in tap water. Thus, this study analyzed 18 multiclass EDCs in tap water from different housing types (i.e., landed and high-rise) and the associated health risks. Sample analyses revealed the presence of 16 EDCs, namely hormones (5), pharmaceuticals (8), a pesticide (1), and plasticizers (2) in tap water, with the prevalent occurrence of bisphenol A up to 66.40 ng/L in high-rise housing. The presence of caffeine and sulfamethoxazole distribution in tap water was significantly different between landed and high-rise housings (t(152) = -2.298, p = 0.023 and t(109) = 2.135, p = 0.035). Moreover, the salinity and conductivity of tap water in high-rise housings were significantly higher compared to those in landed housings (t(122) = 2.411, p = 0.017 and t(94) = 2.997, p = 0.003, respectively). Furthermore, there were no potential health risks of EDCs (risk quotient < 1) estimated in different age groups via drinking water intake. However, EDC variation in different housing types requires simulation of the occurrence, transport, and fate of EDCs in the distribution system and investigation of the underlying factors for effective mitigation, prevention, and intervention.

An automated and high-throughput-screening compatible pluripotent stem cell-based test platform for developmental and reproductive toxicity assessment of small molecule compounds

The embryonic stem cell test (EST) represents the only validated and accepted in vitro system for the detection and classification of compounds according to their developmental and reproductive teratogenic potency. The widespread implementation of the EST, however, in particular for routine application in pharmaceutical development, has not been achieved so far. Several drawbacks still limit the high-throughput screening of potential drug candidates in this format: The long assay period, the use of non-homogeneous viability assays, the low throughput analysis of marker protein expression and the compatibility of the assay procedures to automation. We have therefore introduced several advancements into the EST workflow: A reduction of the assay period, an introduction of homogeneous viability assays, and a straightforward analysis of marker proteins by flow cytometry and high content imaging to assess the impact of small molecules on differentiation capacity. Most importantly, essential parts of the assay procedure have been adapted to lab automation in 96-well format, thus enabling the interrogation of several compounds in parallel. In addition, extensive investigations were performed to explore the predictive capacity of this next-generation EST, by testing a set of well-known embryotoxicants that encompasses the full range of chemical-inherent embryotoxic potencies possible. Due to these significant improvements, the augmented workflow provides a basis for a sensitive, more rapid, and reproducible high throughput screening compatible platform to predict in vivo developmental toxicity from in vitro data which paves the road towards application in an industrial setting.

Graphical abstract

Dietary Contaminants and Their Effects on Zebrafish Embryos

Dietary contaminants are often an over-looked factor in the health of zebrafish. Typically, water is considered to be the source for most contaminants, especially within an aquatic environment. For this reason, source water for zebrafish recirculating systems is highly regulated and monitored daily. Most facilities use reverse osmosis or de-ionized water filtration systems to purify incoming water to ensure that contaminants, as well as pathogens, do not enter their zebrafish housing units. However, diets are rarely tested for contaminants and, in the case of manufactured zebrafish feeds, since the product is marketed for aquaculture or aquarium use it is assumed that the feed is acceptable for animals used for research. The following provides examples as to how contaminants could lead to negative effects on development and behavior of developing zebrafish.

The evaluation of embryotoxicity of Ligusticum chuanxiong on mice and embryonic stem cells

ETHNOPHARMACOLOGICAL RELEVANCE

Chuanxiong (Chuanxiong Rhizoma, CR), the dried rhizome of Ligusticum chuanxiong Hort, has been used during pregnancy for more than 2000 years. However, the embryotoxicity of CR was not evaluated so far. The purpose of this study was to examine the safety and rational use of CR during pregnancy on mice and mouse embryonic stem cell (ES), and to explore the mechanism of embryotoxicity.

AIM OF THE STUDY

This study was carried out to evaluate embryotoxicity of CR decoction in vivo and in vitro, and to explore the mechanism of embryotoxicity from the perspective of bone metabolism.

MATERIALS AND METHODS

In animal experiments, pregnant mice were randomly assigned into 5 groups, i.e. mice were orally treated with CR decoction at dosages of 0 (distilled water, as negative controls), 2, 8, 32 g/kg/d (low, medium and high-dose group), and vitamin A (as positive controls), respectively. Maternal and embryo-fetal parameters were registered after cesarean section. The fetal skeletal development was further assessed with the alizarin red S and Hematoxylin-Eosin staining (H&E staining) and fluorescent imaging. Meanwhile, the mouse embryonic stem cell test model (EST model) was established to objectively evaluate the toxicity of CR on the embryo development. The median inhibitory proliferation values (IC₅₀) for both the mouse embryonic stem cell D3 (ES) and mouse embryonic fibroblast 3T3 (3T3) were detected with MTT assays. After removal of inhibiting factor (LIF), mouse embryonic stem cells spontaneously differentiated into cardiomyocytes, the expression of specific myosin heavy chain gene (β-MHC) contained in cardiomyocytes were detected by q-PCR quantitative analysis, and median inhibitory differentiation concentration (ID₅₀) of ES was obtained. The development toxicity calculation formula was used to determine the embryotoxicity grade of CR decoction. finally, based on the successful induction of osteoblasts, the molecular mechanism of CR embryotoxicity was preliminarily studied based on BMP-Smads signal pathway.

RESULTS

Compared with the negative control group, high, medium, and low doses of CR decoction had no significant effect on the maternal body weight and uterine weight (P > 0.05), as well as on the maternal liver, heart, and kidneys. The observation results showed that high dose of CR decoction significantly increase the number of absorbed fetuses (P < 0.05). The EST model was successfully established, the IC₅₀ 3T3, IC₅₀ ES and ID₅₀ ES of CR were 9.39 mg/mL, 18.78 mg/mL, and 10.20 mg/mL, respectively. CR was classified as weak embryonic development toxicity by the EST linear discriminant formula. Meanwhile, osteoblasts were successfully induced in vitro, the relative expression levels of BMP2, BMPR2, Smad1, and Smad5 were down-regulated in varying degrees after 3, 6, and 9 days of treatment with different concentration gradients of CR decoction.

CONCLUSIONS

Combining in vivo and in vitro experiments, CR showed a potential embryotoxicity. The mechanism of embryotoxicity may be related to inhibiting the expression of key genes in the BMP-SMADs signaling pathway. In the clinical application, the normal dosage of CR is safe to a certain extent. However, when the dosage is too high (160 g/60 kg/d), there may be a risk of embryotoxicity.

Pluripotent Stem Cells in Developmental Toxicity Testing: A Review of Methodological Advances

Millions of children are born each year with a birth defect. Many of these defects are caused by environmental factors, although the underlying etiology is often unknown. In vivo mammalian models are frequently used to determine if a chemical poses a risk to the developing fetus. However, there are over 80 000 chemicals registered for use in the United States, many of which have undergone little safety testing, necessitating the need for higher-throughput methods to assess developmental toxicity. Pluripotent stem cells (PSCs) are an ideal in vitro model to investigate developmental toxicity as they possess the capacity to differentiate into nearly any cell type in the human body. Indeed, a burst of research has occurred in the field of stem cell toxicology over the past decade, which has resulted in numerous methodological advances that utilize both mouse and human PSCs, as well as cutting-edge technology in the fields of metabolomics, transcriptomics, transgenics, and high-throughput imaging. Here, we review the wide array of approaches used to detect developmental toxicants, suggest areas for further research, and highlight critical aspects of stem cell biology that should be considered when utilizing PSCs in developmental toxicity testing.

Individual and combined cytotoxicity assessment of zearalenone with ochratoxin A or α-zearalenol by full factorial design

The combined mycotoxins zearalenone (ZEA) with ochratoxin A (OTA) or α-zearalenol (α-ZOL) are frequently found together in milk. Toxicological data concerning the combined effects of these mycotoxins are sparse. In present study, individual and combined ZEA, OTA and α-ZOL caused cytotoxicity and oxidative damage, including reductions in intracellular superoxide dismutase and glutathione peroxidase activities and glutathione content, along with increases in malonaldehyde content on human Hep G2 cells after 48 h of exposure. Among individual mycotoxins, OTA had the greatest cytotoxic effect followed by α-ZOL. Compared with individual mycotoxins, combinations produced more serious negative effects, more importantly, ZEA + OTA was antagonistic for these effects, whereas ZEA + α-ZOL was antagonistic at low concentrations, but synergistic at high concentrations of ZEA, which were evaluated by 3 × 3 full factorial analysis and estimated marginal means plots. Our results also demonstrated a significant correlation between cytotoxicity and oxidative damage in response to these combinations.

Prospects and Frontiers of Stem Cell Toxicology

The development of stem cell biology has revolutionized regenerative medicine and its clinical applications. Another aspect through which stem cells would benefit human health is their use in toxicology. In fact, owing to their ability to differentiate into all the lineages of the human body, including germ cells, stem cells, and, in particular, pluripotent stem cells, can be utilized for the assessment, in vitro, of embryonic, developmental, reproductive, organ, and functional toxicities, relevant to human physiology, without employing live animal tests and with the possibility of high throughput applications. Thus, stem cell toxicology would tremendously assist in the toxicological evaluation of the increasing number of synthetic chemicals that we are exposed to, of which toxicity information is limited. In this review, we introduce stem cell toxicology, as an emerging branch of in vitro toxicology, which offers quick and efficient alternatives to traditional toxicology assessments. We first discuss the development of stem cell toxicology, and we then emphasize its advantages and highlight the achievements of human pluripotent stem cell-based toxicity research.

Interactions between three typical endocrine-disrupting chemicals (EDCs) in binary mixtures exposure on myocardial differentiation of mouse embryonic stem cell

In recent years, various kinds of endocrine-disrupting chemicals (EDCs) have been detected in human blood and urine. Thus, it was important to investigate the combined toxicity effect of EDCs. In the present study, we evaluated the individual and combined developmental toxicities of three classic EDCs: perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA), and bisphenol A (BPA) by embryonic stem cell test (EST). The similarities and differences between combination of same chemical group as well as different chemical groups were investigated in this research. Our results showed that the three compounds were all classified as weak embryotoxicity. The results of co-exposure revealed that there was synergistic action in combination of PFOS and BPA on myocardial differentiation. However, in all endpoints, the combined effects between PFOA with PFOS or BPA were both additive action. Therefore, we concluded that the additive effects were found in most different EDC mixtures whether they had similar structure or not. On the other hand, synergistic action was observed in a mixture of EDCs that belonged to a different chemical groups.

Effect of bisphenol A on reproductive processes: A review of in vitro, in vivo and epidemiological studies

As bisphenol A (BPA) is characterized by a pronounced influence on human hormonal regulation, particular attention has been aimed at understanding its role in reproductive processes in males and females, as well as on fetal development. Owing to the increasing number of alarming reports on the negative consequences of the presence of BPA in human surroundings, more and more studies are being undertaken to clarify the negative effects of BPA on human reproductive processes. The aim of this work was to collect and summarize data on the influence of BPA exposure on reproductive health. Based on an analysis of selected publications it was stated that there is strong proof confirming that BPA is an ovarian, uterine and prostate toxicant at a level below the lowest observed adverse effect level (50 mg kg^-1 bodyweight) as well as a level below the proposed safe level (4 μg kg^-1 bodyweight). It seems there is also reliable evidence in relation to the negative effect of BPA on sperm quality and motility. Limited evidence also pertains to the case of the potential of BPA to affect polycystic ovary syndrome occurrence. Although in epidemiological studies this disease was common, in studies on animal models such results were still not confirmed. No unambiguous results of epidemiological studies and with animal models were obtained in relation to the evaluation of associations between BPA and implantation failure in women, evaluation of associations between BPA and sexual dysfunction in men, and impact of BPA on birth rate, birth weight and length of gestation. Copyright © 2017 John Wiley & Sons, Ltd.

Autism genes are selectively targeted by environmental pollutants including pesticides, heavy metals, bisphenol A, phthalates and many others in food, cosmetics or household products

The increasing incidence of autism suggests a major environmental influence. Epidemiology has implicated many candidates and genetics many susceptibility genes. Gene/environment interactions in autism were analysed using 206 autism susceptibility genes (ASG's) from the Autworks database to interrogate ∼1 million chemical/gene interactions in the comparative toxicogenomics database. Any bias towards ASG's was statistically determined for each chemical. Many suspect compounds identified in epidemiology, including tetrachlorodibenzodioxin, pesticides, particulate matter, benzo(a)pyrene, heavy metals, valproate, acetaminophen, SSRI's, cocaine, bisphenol A, phthalates, polyhalogenated biphenyls, flame retardants, diesel constituents, terbutaline and oxytocin, inter alia showed a significant degree of bias towards ASG's, as did relevant endogenous agents (retinoids, sex steroids, thyroxine, melatonin, folate, dopamine, serotonin). Numerous other suspected endocrine disruptors (over 100) selectively targeted ASG's including paraquat, atrazine and other pesticides not yet studied in autism and many compounds used in food, cosmetics or household products, including tretinoin, soy phytoestrogens, aspartame, titanium dioxide and sodium fluoride. Autism polymorphisms influence the sensitivity to some of these chemicals and these same genes play an important role in barrier function and control of respiratory cilia sweeping particulate matter from the airways. Pesticides, heavy metals and pollutants also disrupt barrier and/or ciliary function, which is regulated by sex steroids and by bitter/sweet taste receptors. Further epidemiological studies and neurodevelopmental and behavioural research is warranted to determine the relevance of large number of suspect candidates whose addition to the environment, household, food and cosmetics might be fuelling the autism epidemic in a gene-dependent manner.

The treatment of phenolic contaminants from shale gas drilling wastewater: a comparison with UV-Fenton and modified UV-Fenton processes at neutral pH

In this study, the treatment efficiency of phenolic contaminants from drilling wastewater was evaluated with three different UV-Fenton processes.

Assessment of Bisphenol A (BPA) neurotoxicity in vitro with mouse embryonic stem cells

The adverse effects of environmental pollution on our well-being have been intensively studied with many in vitro and in vivo systems. In our group, we focus on stem cell toxicology due to the multitude of embryonic stem cell (ESC) properties which can be exerted in toxicity assays. In fact, ESCs can differentiate in culture to mimic embryonic development in vivo, or specifically to virtually any kind of somatic cells. Here, we used the toxicant Bisphenol A (BPA), a chemical known as a hazard to infants and children, and showed that our stem cell toxicology system was able to efficiently recapitulate most of the toxic effects of BPA previously detected by in vitro system or animal tests. More precisely, we demonstrated that BPA affected the proper specification of germ layers during our in vitro mimicking of the embryonic development, as well as the establishment of neural ectoderm and neural progenitor cells.

Assessment of the embryotoxicity of four Chinese herbal extracts using the embryonic stem cell test

Rhizoma Atractylodes macrocephala, Radix Isatidis, Coptis chinensis and Flos Genkwa are common herbal remedies used by pregnant woman in China. In this study, their potential embryotoxicity was assessed using the embryonic stem cell test (EST) and a prediction model. The potential embryotoxicity of the herbs was based on three endpoints: the concentrations of the compounds that inhibited the proliferation of 50% of embryonic stem cells (ESCs) (IC50ES), the concentrations that inhibited 50% of 3T3 cells (IC503T3), and the concentrations that inhibited the differentiation of 50% of ESCs (ID50ES). The results revealed that Rhizoma Atractylodes macrocephala and Radix Isatidis are non-embryotoxic compounds. Coptis chinensis extracts appeared to demonstrated weak embryotoxicity, and Flos Genkwa exhibited strong embryotoxicity. These results may be useful in guiding the clinical use of these herbs and in expanding the application of the EST to the field of traditional Chinese medicine.

Long-term effects of chromatin remodeling and DNA damage in stem cells induced by environmental and dietary agents

The presence of histones acts as a barrier to protein access; thus chromatin remodeling must occur for essential processes such as transcription and replication. In conjunction with histone modifications, DNA methylation plays critical roles in gene silencing through chromatin remodeling. Chromatin remodeling is also interconnected with the DNA damage response, maintenance of stem cell properties, and cell differentiation programs. Chromatin modifications have increasingly been shown to produce long-lasting alterations in chromatin structure and transcription. Recent studies have shown environmental exposures in utero have the potential to alter normal developmental signaling networks, physiologic responses, and disease susceptibility later in life during a process known as developmental reprogramming. In this review we discuss the long-term impact of exposure to environmental compounds, the chromatin modifications that they induce, and the differentiation and developmental programs of multiple stem and progenitor cell types altered by exposure. The main focus is to highlight agents present in the human lifestyle that have the potential to promote epigenetic changes that impact developmental programs of specific cell types, may promote tumorigenesis through altering epigenetic marks, and may be transgenerational, for example, those able to be transmitted through multiple cell divisions.