The regulation of endocrine-disrupting chemicals to minimize their impact on health

Shape-controlled asymmetric bowl-like PDA@Au substrates for sensitive SERS detection of anabolic androgenic steroids

The widespread accumulation of androgenic steroid endocrine disruptors in water and food has garnered increasing attention due to their significant risks to ecosystems and human health. These steroids, which cannot be completely eliminated, highlight the urgent need for advanced detection technologies. In this study, we present a novel emulsion-induced interface-anisotropic assembly strategy to synthesize bowl-like mesoporous polydopamine (PDA) particles, which exhibit high sensitivity in surface-enhanced Raman scattering (SERS) detection. In-situ reduction of chloroauric acid leads to the formation of Au nanoparticles (NPs) on the PDA surface, where synergistic Au-N interactions enhance the SERS performance. The distinctive bowl-like structure generates abundant "hot spots" on both sides, resulting in exceptional sensitivity. The low relative standard deviation (RSD) values (<11.7 %) across different PDA@Au NPs, along with real sample analyses (1.9-4.0 %), confirm the high reproducibility and uniformity of the SERS substrates, all achieved without the use of additional reducing agents. This cost-effective and straightforward method eliminates the need for complex surface treatments, making it particularly suitable for real-time detection of anabolic steroids across various matrices. These findings underscore the potential of bowl-like PDA materials for broader applications in clinical diagnostics, environmental monitoring, and sports doping control.

Prompting large language models to extract chemical‒disease relation precisely and comprehensively at the document level: an evaluation study

Given the scarcity of annotated data, current deep learning methods face challenges in the field of document-level chemical-disease relation extraction, making it difficult to achieve precise relation extraction capable of identifying relation types and comprehensive extraction tasks that identify relation-related factors. This study tests the abilities of three large language models (LLMs), GPT3.5, GPT4.0, and Claude-opus, to perform precise and comprehensive extraction in document-level chemical-disease relation extraction on a self-constructed dataset. Firstly, based on the task characteristics, this study designs six workflows for precise extraction and five workflows for comprehensive extraction using prompting engineering strategies. The characteristics of the extraction process are analyzed through the performance differences under different workflows. Secondly, this study analyzes the content bias in LLMs extraction by examining the extraction effectiveness of different workflows on different types of content. Finally, this study analyzes the error characteristics of extracting incorrect examples by the LLMs. The experimental results show that: (1) The LLMs demonstrate good extraction capabilities, achieving the highest F1 scores of 87% and 73% respectively in the tasks of precise extraction and comprehensive extraction; (2) In the extraction process, the LLMs exhibit a certain degree of stubbornness, with limited effectiveness of prompting engineering strategies; (3) In terms of extraction content, the LLMs show a content bias, with stronger abilities to identify positive relations such as induction and acceleration; (4) The essence of extraction errors lies in the LLMs' misunderstanding of the implicit meanings in biomedical texts. This study provides practical workflows for precise and comprehensive extraction of document-level chemical-disease relations and also indicates that optimizing training data is the key to building more efficient and accurate extraction methods in the future.

The connection between Bayesian networks and adverse outcome pathway (AOP) networks and how to use it for predicting drug toxicity

There is significant interest in combining adverse outcome pathways (AOPs) with Bayesian networks (BNs) because of their shared representation using directed acyclic graphs (DAGs). However, it has not been verified empirically whether AOP networks are mathematically congruent with BNs. Furthermore, important properties for BNs, such as Markov blankets, have not been emphasized, which is a missed opportunity for simplifying and optimizing the model. Here, we summarize the connection between AOP networks and BNs and explore the implications for toxicity modeling. We also present a case study in drug-related liver toxicity. Our results confirm that AOP networks are congruent mathematically with BNs, with incorporation of the mathematical properties of BN leading to significantly simplified and more efficient models.

Interpretable machine learning-based insights into early-life endocrine disruptor exposure and small vulnerable newborns

Early-life exposure to endocrine-disrupting chemicals (EDCs) may contribute to small vulnerable newborns, including conditions such as being small for gestational age (SGA) and preterm birth (PTB), yet evidence remains limited. This study, which is based on 739 mother-infant pairs in the Chinese Jiashan Birth Cohort (2016-2018), including 39 SGA and 38 PTB cases, employed interpretable machine learning to elucidate the isolated effects of 34 EDCs on SGA and PTB risk and sex interactions in a multi-substance exposure context. Extra Trees and CatBoost classifiers performed best for SGA and PTB, respectively, achieving sensitivities of 0.60 and 0.73 and specificities of 0.82 and 0.97. For SGA, key predictors included bisphenol A (2,3-dihydroxypropyl) glycidyl ether (BADGE-H2O), benzophenone (bZp), bisphenol A bis(2,3-dihydroxypropyl) ether (BADGE-2H2O), propyl paraben (PrP), and 2-methylthio-benzothiazole (2-Me-S-BTH). Lower exposures to BADGE-H2O, bZp, and BADGE-2H2O (concentrations below 0.21, 4.22, and 0.93 μg·g-1 creatinine, respectively) and higher exposure to 2-Me-S-BTH (above 0.15 μg·g-1 creatinine) were both associated with increased SGA risk. Notably, BADGE-H2O, BADGE-2H2O, and PrP showed significant interactions with fetal sex. For PTB, key predictors included ethyl paraben (EtP), methyl paraben (MeP), bZp, BADGE-H2O, and 1H-benzotriazole (1-H-BTR). Lower BADGE-H2O and higher EtP and bZp exposures increased PTB risk (< 0.10 and > 0.01 and 0.60 μg·g-1 creatinine, respectively). Male fetuses appeared more susceptible to EtP and MeP, and female fetuses were more susceptible to 1-H-BTR. Bayesian kernel machine regression was performed to compare the results. This study demonstrated the potential of interpretable machine learning in environmental epidemiology.

Novel Approach to Screen Endocrine-Disrupting Chemicals via Endocrine-Enhanced Reduced Human Transcriptome

Endocrine-disrupting chemicals (EDCs) can interfere with multiple pathways and trigger different modes of action. Thus, the traditional EDC in vitro screening processes often require a battery of bioassays to cover multiple target pathways. Here we developed an endocrine-enhanced reduced human transcriptome (ERHT) focused on hormone receptor signaling induced by the EDCs regulating specific genes. ERHT was developed based on 1200 prioritized genes covering 110 endocrine-related biological pathways across eight potential adverse outcomes. The ability of this approach to identify EDCs was derived from machine learning of 1068 dose-dependent transcriptome profiles and enhanced by quantifying chemical-induced critical pathway responses, and thus, it demonstrated excellent classification performance (AUC = 0.84 ± 0.03) in internal cross-validation. We ultimately applied this approach to known EDCs and inactive substances to validate the reliability of this approach. Through external validation on 210 chemicals, the extrapolation accuracy exceeded 80%, demonstrating the outstanding practical performance of this approach. Meanwhile, the pathway responses induced by the same chemical were consistent with the experimental results reported by multiple sequencing platforms, highlighting the robustness of this approach. The above results demonstrate that this approach can provide novel insights for EDCs' high-throughput screening and comprehensive toxic mechanisms through biological pathways.

Development of an Efficient and Generalized MTSCAM Model to Predict Liquid Chromatography Retention Times of Organic Compounds

Accurate prediction of liquid chromatographic retention times is becoming increasingly important in nontargeted screening applications. Traditional retention time approaches heavily rely on the use of standard compounds, which is limited by the speed of synthesis and manufacture of standard products, and is time-consuming and labor-intensive. Recently, machine learning and artificial intelligence algorithms have been applied to retention time prediction, which show unparalleled advantages over traditional experimental methods. However, existing retention time prediction methods usually suffer from the scarcity of comprehensive training datasets, sparsity of valid data, and lack of classification in datasets, resulting in poor generalization capability and accuracy. In this study, a dataset for 10,905 compounds was constructed including their retention times. Next, an innovative classification system was implemented, classifying 10,905 compounds into a 3-tier hierarchy across 141 classes, based on functional group weighting. Then, data augmentation was performed within each category using simplified molecular input line entry system (SMILES) enumeration combined with structural similarity expansion. Finally, by training the optimal quantitative structure-retention relationship (QSRR) models for each category of compounds and selecting the best-fitting model for prediction via discriminant analysis during the prediction period, a novel and universal high-throughput retention time prediction model was established. The results demonstrate that this model achieves an R 2 of 0.98 and an average prediction error of 23 s, outperforming currently published models. This study provides a scientific basis for high throughput and rapid prediction of unknown pollutants, data mining, nontargeted screening, etc.

Using Intervention Mapping and Behavior Change Techniques to Develop a Health Promotion Intervention on Endocrine Disruptors: Development Study

Endocrine disruptors (EDs) are substances that interfere with the endocrine system, posing risks to health across various life stages, particularly during adolescence when hormonal changes are pronounced. Despite the recognition of adolescents as vulnerable, there have been few interventions targeting their exposure to EDs. This study developed the COPE ADOS program using the intervention mapping (IM) framework to enhance adolescents' knowledge and skills in identifying and mitigating exposure to EDs. The IM framework guided the creation of the program through four steps: conducting a needs assessment, formulating program objectives, selecting relevant behavioral theories, and developing a logical model. The need assessment conducted through focus groups revealed significant knowledge gaps and misconceptions about EDs among adolescents, leading to the establishment of six performance objectives aimed at addressing attitude, knowledge, risk perception, self-efficacy, and skills. As a result, 15 educational tools were created. The COPE ADOS program represents a novel, collaborative effort tailored to the needs of students and demonstrates the potential of the IM framework in developing effective health interventions for adolescents. Future research should evaluate the impact of this program on reducing ED exposure among high school students.

The role of plastics in allergy, immunology, and human health: What the clinician needs to know and can do about it

The effects of plastics on human health include allergy, atopy, asthma, and immune disruption, but the consequences of chemicals used in plastic materials span nearly every organ system and age group as well. Behavioral interventions to reduce plastic chemical exposures have reduced exposure in low- and high-income populations, yet health care providers know little about plastic chemical effects and seldom offer steps to patients to limit exposure. Health care facilities also use many products that increase the risk of chemical exposures, particularly for at-risk populations such as children in neonatal intensive care units. Given that disparities in plastic chemical exposure are well documented, collaborative efforts are needed between scientists and health care organizations, to develop products that improve provider knowledge about chemicals used in plastic materials and support the use of safer alternatives in medical devices and other equipment.

3-methyl-4-nitrophenol disturbs the maternal-to-zygotic transition of early embryos by damaging mitochondrial function and histone modification

3-methyl-4-nitrophenol (PNMC), a chemical prevalent in various industries for drug, dye, and leather production, also serves as a primary byproduct of organophosphate insecticides. Despite its global recognition as an endocrine disruptor with documented reproductive toxicity, its detrimental impact on preimplantation embryonic development has yet to be thoroughly investigated. In this study, through the in vitro culture of mice embryos, it was initially observed that even low concentrations of PNMC exposure led to a significant reduction in blastocyst formation and a sharp decline in the ratio of inner cell mass within the blastocysts. SMART-seq2 transcriptome sequencing further confirmed that PNMC treatment disrupted global gene expression in 2-cell embryos, with differentially expressed genes enriched in multiple signaling pathways, including those related to autophagy, apoptosis, fertilization, embryonic development, transcription, and mRNA processing. Integration of transcriptome data with open databases revealed that both zygotic genome activation genes and maternal factors experienced significant transcript-level disruptions. Moreover, the study demonstrated that these gene expression changes were closely associated with mitochondrial dysfunction, evidenced by diminished mitochondrial membrane potential, reduced ATP production, aberrant expression of mitochondria-related genes, increased ROS accumulation, and heightened DNA damage in PNMC-treated embryos. Additionally, PNMC exposure induced defects in histone modification, as shown by altered levels of H3K9me3 and H3K27me3, H3K9ac and H3K27ac. Lastly, the findings indicated that PNMC triggered apoptosis in embryos, validated by elevated BAX and CASPASE3 expression, alongside positive TUNEL staining. In summary, PNMC exposure impairs the maternal-to-zygotic transition, likely through mitochondrial dysfunction and histone modification, culminating in developmental arrest and apoptosis in mouse preimplantation embryos.

The ENDOMIX perspective: how everyday chemical mixtures impact human health and reproduction by targeting the immune system†

Endocrine-disrupting chemicals are natural and synthetic compounds found ubiquitously in the environment that interfere with the hormonal-immune axis, potentially impacting human health and reproduction. Exposure to endocrine-disrupting chemicals has been associated with numerous health risks, such as neurodevelopmental disorders, metabolic syndrome, thyroid dysfunction, infertility, and cancers. Nevertheless, the current approach to establishing causality between these substances and disease outcomes has limitations. Epidemiological and experimental research on endocrine-disrupting chemicals faces challenges in accurately assessing chemical exposure and interpreting non-monotonic dose response curves. In addition, most studies have focused on single chemicals or simple mixtures, overlooking complex real-life exposures and mechanistic insights, in particular regarding endocrine-disrupting chemicals' impact on the immune system. The ENDOMIX project, funded by the EU's Horizon Health Program, addresses these challenges by integrating epidemiological, risk assessment, and immunotoxicology methodologies. This systemic approach comprises the triangulation of human cohort, in vitro, and in vivo data to determine the combined effects of chemical mixtures. The present review presents and discusses current literature regarding human reproduction in the context of immunotolerance and chemical disruption mode of action. It further underscores the ENDOMIX perspective to elucidate the impact of endocrine-disrupting chemicals on immune-reproductive health.

Impact of Endocrine Disruptors on the Genitourinary Tract

Over the last decades, the human species has seen an increase in the incidence of pathologies linked to the genitourinary tract. Observations in animals have allowed us to link these increases, at least in part, to changes in the environment and, in particular, to an increasing presence of endocrine disruptors. These can be physical agents, such as light or heat; natural products, such as phytoestrogens; or chemicals produced by humans. Endocrine disruptors may interfere with the signaling pathways mediated by the endocrine system, particularly those linked to sex hormones. These factors and their general effects are presented before focusing on the male and female genitourinary tracts by describing their anatomy, development, and pathologies, including bladder and prostate cancer.

Pediatric Obesity Treatment: Considerations for Diabetes Educators and Clinicians

Prevalence rates of pediatric obesity and diabetes are rising, and pediatric health care professionals are ideally situated to address these chronic diseases using a patient- and family-centered approach. This article reviews key elements of evaluation that can inform treatment and emphasizes a comprehensive, team-based strategy. Treatment begins with motivational interviewing and building a foundation of intensive health behavior and lifestyle treatment, followed by pharmacotherapy and metabolic and bariatric surgery, when indicated.

Unlocking the roles of wheat root exudates in regulating laccase-catalyzed estrogen humification

While laccase humification has an efficient capacity to convert estrogenic pollutants, the roles of wheat (Triticum aestivum L.) root exudates (W-REs) in the enzymatic humification remain poorly understood. Herein, we presented the research into the effects of W-REs on 17β-estradiol (E2) and bisphenol A (BPA) conversion in vitro laccase humification. W-REs inhibited E2 removal but promoted BPA conversion in the enzymatic humification, and the first-order kinetic constants for E2 and BPA were 0.27-0.69 and 0.28-0.55 h-1, respectively. Specialized small phenols and amino acids in W-REs were susceptible to laccase humification, resulting in increased copolymerization of estrogen and W-REs. In greenhouse hydroponics, the accumulated amounts of E2 (BPA) in the roots and shoots were estimated to be 0.87 (2.15) and 0.43 (0.51) nmol·plant-1 at day 3, respectively. By forming low- and eventually non-toxic copolymeric precipitates between estrogen and W-REs, laccase humification lowered the phytotoxicity and bioavailability of estrogen in the rhizosphere solution, consequently relieving its uptake, accumulation, and distribution in the wheat cells. This work sheds light on the roles of W-REs in regulating laccase-catalyzed estrogen humification, and gives an insight into the path of addressing organic contamination in the rhizosphere and ensuring food safety.

Differentiation of adsorption and degradation in steroid hormone micropollutants removal using electrochemical carbon nanotube membrane

The growing concern over micropollutants in aquatic ecosystems motivates the development of electrochemical membrane reactors (EMRs) as a sustainable water treatment solution. Nevertheless, the intricate interplay among adsorption/desorption, electrochemical reactions, and byproduct formation within EMR complicates the understanding of their mechanisms. Herein, the degradation of micropollutants using an EMR equipped with carbon nanotube membrane are investigated, employing isotope-labeled steroid hormone micropollutant. The integration of high-performance liquid chromatography with a flow scintillator analyzer and liquid scintillation counting techniques allows to differentiate hormone removal by concurrent adsorption and degradation. Pre-adsorption of hormone is found not to limit its subsequent degradation, attributed to the rapid adsorption kinetics and effective mass transfer of EMR. This analytical approach facilitates determining the limiting factors affecting the hormone degradation under variable conditions. Increasing the voltage from 0.6 to 1.2 V causes the degradation dynamics to transition from being controlled by electron transfer rates to an adsorption-rate-limited regime. These findings unravels some underlying mechanisms of EMR, providing valuable insights for designing electrochemical strategies for micropollutant control.

Ultrasonic decomposition of endocrine disrupting Compounds - A review

Endocrine disrupting compounds (EDCs) need to be removed by efficient treatment methods as they are a major concern for both human and environmental health. To reduce the impact of EDCs in water, this review examines the use of ultrasonic degradation processes. Following an overview of EDCs and their origins, the basic concepts of sonochemistry are examined, highlighting the potential of ultrasound in chemical reactions. An in-depth analysis of the variables that affect the ultrasonic degradation of EDCs, such as frequency, intensity/power, temperature and solution chemistry, prepares the reader for a case study investigation focusing on specific EDCs. The study also looks at synergistic methods, emphasizing how hybrid ultrasonic systems can improve removal efficiency. The study provides a comprehensive overview of the use of sonochemistry in the treatment of EDCs by addressing current issues and suggesting future research directions. The aim of this review paper is to provide insightful analysis and useful suggestions for scientists working on EDC remediation projects.

Differences in endocrine and reproductive responses to substance exposure across generations: highlighting the importance of complementary findings

This article analyzes the results from 112 Extended One-Generation Reproductive Toxicity studies. The objective was to determine if test animals show consistent endocrine and reproductive effects within the same and across different generations and life stages. The analysis, grounded in a comprehensive Binary Matrix, included 530 observed effects and 193 unique, statistically significant associations. Associations' strength was quantified using Jaccard (J) coefficients to measure effect co-occurrence in the same study. Associated effects co-occur infrequently across the whole dataset (median J = 0.231). However, specific patterns emerged: associations of same effects across generations exhibited a higher strength (median J = 0.400) compared to associations of different effects (median J = 0.222). Notably, associations with effects observed in both the parental animals of the adult first filial generation (P1) and developing second filial generations (dF2) demonstrated J coefficients (with medians ranging from 0.300 to 0.430) that were approximately twofold higher than those of other associations. Consistently, equivalent life stage associations across generations revealed statistically significant higher association strengths for the P1 and dF2 generations (medians of 0.375 and 0.333, respectively) compared to other generations (medians of 0.200 and 0.174), possibly due to longer exposure duration and altered cross-talk between pregnant P1 dam and its conceptus. Overall, it is concluded that co-occurrence of associated effects in the same study is rather infrequent and that associations with effects in P1 and dF2 are stronger than all other associations. In general, the findings underscore the importance of independently analyzing each effect per generation due to the generally low co-occurrence rates of associated effects, challenging traditional expectations of generational continuity in toxic effects.

Endocrine Disruptors in Pregnancy: Effects on Mothers and Fetuses-A Review

Background/Objectives: Endocrine disruptors are ubiquitous agents in the environment and are present in everyday consumer products. These agents can interfere with the endocrine system, and subsequently the reproductive system, especially in pregnancy. An increasing number of studies have been conducted to discover and describe the health effects of these agents on humans, including pregnant women, their fetuses, and the placenta. This review discusses prenatal exposure to various endocrine disruptors, focusing on bisphenols, phthalates, organophosphates, and perfluoroalkyl substances, and their effects on pregnancy and fetal development. Methods: We reviewed the literature via the PubMed and EBSCO databases and included the most relevant studies. Results: Our findings revealed that several negative health outcomes were linked to endocrine disruptors. However, despite the seriousness of this topic and the abundance of research on these agents, it remains challenging to draw strong conclusions about their effects from the available studies. This does not allow for strong, universal guidelines and might result in poor patient counseling and heterogeneous approaches to regulating endocrine disruptors. Conclusions: The seriousness of this matter calls for urgent efforts, and more studies are needed in this realm, to protect pregnant patients, and ultimately, in the long term, society.

Parabens effects on female reproductive health - Review of evidence from epidemiological and rodent-based studies

Parabens have been used as antimicrobial preservatives since the 1920s. The prevalent use of parabens increases their detection in the environment and in women's biological samples including reproductive tissues. Recent studies suggest parabens may alter endocrine function and thus female reproductive health may be affected. In this literature review, we summarize findings on parabens and female reproduction while focusing on epidemiological and rodent-based studies. The topics reviewed include paraben effects on cyclicity, pregnancy, newborn and pubertal development, reproductive hormones, and ovarian and uterine specific outcomes. Overall, the scientific literature on paraben effects on female reproduction is limited and with some conflicting results. Yet, some epidemiological and/or rodent-based experimental studies report significant findings in relation to paraben effects on cyclicity, fertility, gestation length, birth weight, postnatal development and pubertal onset, hormone levels, and hormone signaling in reproductive tissues. Future epidemiological and experimental studies are needed to better understand paraben effects on female reproduction while focusing on human related exposures including mixtures, physiologic concentrations of parabens, and multi-generational studies.

Aptamer biosensor design for the detection of endocrine-disrupting chemicals small organic molecules using novel bioinformatics methods

Endocrine-disrupting chemicals (EDCs) are substances that can disrupt the normal functioning of hormones.Using aptamers, which are biological recognition elements, biosensors can quickly and accurately detect EDCs in environmental samples. However, the elucidation of aptamer structures by conventional methods is highly challenging due to their complexity. This has led to the development of three-dimensional aptamer structures based on different models and techniques. To do this, we developed a way to predict the 3D structures of the SS DNA needed for this sequence by starting with an aptamer sequence that has biosensor properties specific to bisphenol-A (BPA), one of the chemicals found in water samples that can interfere with hormones. In addition, we will elucidate the intermolecular mechanisms and binding affinity between aptamers and endocrine disruptors using bioinformatics techniques such as molecular docking, molecular dynamics simulation, and binding energies. The outcomes of our study are to compare modeling programs and force fields to see how reliable they are and how well they agree with results found in the existing literature, to understand the intermolecular mechanisms and affinity of aptamer-based biosensors, and to find a new way to make aptamers that takes less time and costs less.

Environmental endocrine disruptor-induced mitochondrial dysfunction: a potential mechanism underlying diabetes and its complications

Diabetes and its complications significantly affect individuals' quality of life. The etiology of diabetes mellitus and its associated complications is complex and not yet fully understood. There is an increasing emphasis on investigating the effects of endocrine disruptors on diabetes, as these substances can impact cellular processes, energy production, and utilization, ultimately leading to disturbances in energy homeostasis. Mitochondria play a crucial role in cellular energy generation, and any impairment in these organelles can increase susceptibility to diabetes. This review examines the most recent epidemiological and pathogenic evidence concerning the link between endocrine disruptors and diabetes, including its complications. The analysis suggests that endocrine disruptor-induced mitochondrial dysfunction-characterized by disruptions in the mitochondrial electron transport chain, dysregulation of calcium ions (Ca2+), overproduction of reactive oxygen species (ROS), and initiation of signaling pathways related to mitochondrial apoptosis-may be key mechanisms connecting endocrine disruptors to the development of diabetes and its complications.

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.

Impact of antenatal exposure to a mixture of persistent organic pollutants on intellectual development

OBJECTIVE

Strong experimental evidence exists that several endocrine disrupting chemicals (EDCs) have neurobehavioral toxicity. However, evidence of associations between prenatal exposure and child's cognitive development is inconsistent. Moreover, toxicants are generally analyzed one by one without considering aggregate effects. We examined here the impact of a prenatal exposure to a mixture of persistent organic pollutants (POPs) on intellectual abilities in preschool children, and compared their effects to those described in the literature.

METHODS

Sixty-two children were included in a longitudinal cohort. Four organochlorine pesticides, four polychlorinated biphenyls (PCBs) and seven perfluorinated compounds (PFCs) were measured in cord blood. Intellectual abilities were assessed at 6 years of age using the Wechsler Preschool and Primary Scale of Intelligence 4th ed. (WPPSI-IV). We examined the associations between a mixture of POPs and cognitive performances using principal components approach (PCA) and weighted quantile sum (WQS) regression taking sex difference into account.

RESULTS

No negative correlation was found when analyses were performed on boys and girls together. In sex-stratified analyses, lower scores in full scale intelligence quotient (FSIQ) and fluid reasoning index (FRI) were observed in boys most exposed to a mixture of POPs. Increase of the WQS index was also associated with lower verbal comprehension index (VCI) scores in girls only. No other negative correlation was found using both WQS and PCA models.

CONCLUSION

Our study suggests deleterious associations between antenatal exposure to a mixture of POPs and sex-specific cognitive level, clarifying some trends described in the literature.

Zirconium-Based Metal-Organic Frameworks with Free Hydroxy Groups for Enhanced Perfluorooctanoic Acid Uptake in Water

Perfluorooctanoic acid (PFOA) is a highly recalcitrant organic pollutant, and its bioaccumulation severely endangers human health. While various methods are developed for PFOA removal, the targeted design of adsorbents with high efficiency and reusability remains largely unexplored. Here the rational design and synthesis of two novel zirconium-based metal‒organic frameworks (MOFs) bearing free ortho-hydroxy sites, namely noninterpenetrated PCN-1001 and twofold interpenetrated PCN-1002, are presented. Single crystal analysis of the pure ligand reveals that intramolecular hydrogen bonding plays a pivotal role in directing the formation of MOFs with free hydroxy groups. Furthermore, the transformation from PCN-1001 to PCN-1002 is realized. Compared to PCN-1001, PCN-1002 displays higher chemical stability due to interpenetration, thereby demonstrating an exceptional PFOA adsorption capacity of up to 632 mg g-1 (1.53 mmol g-1), which is comparable to the reported record values. Moreover, PCN-1002 shows rapid kinetics, high selectivity, and long-life cycles in PFOA removal tests. Solid-state nuclear magnetic resonance results and density functional theory calculations reveal that multiple hydrogen bonds between the free ortho-hydroxy sites and PFOA, along with Lewis acid-base interaction, work collaboratively to enhance PFOA adsorption.

Association of prenatal exposure to phthalates and synthetic phenols with pubertal development in three European cohorts

BACKGROUND

There is limited epidemiological evidence on the association of prenatal exposure to phthalates and synthetic phenols with altered pubertal timing.

OBJECTIVE

To examine the association of prenatal exposure to phthalates, bisphenol A (BPA), parabens, benzophenone 3 (BP-3), and triclosan (TCS) with pubertal development in girls and boys from three European cohorts.

METHODS

Urinary metabolites of six different phthalate diesters (DEP, DiBP, DnBP, BBzP, DEHP, and DiNP), BPA, methyl- (MePB), ethyl- (EtPB), propyl- (PrPB), and butyl-paraben (BuPB), BP-3, and TCS were quantified in one or two (1st and 3rd trimester) urine samples collected during pregnancy (1999-2008) from mothers in three birth cohorts: INMA (Spain), EDEN (France), and MoBa (Norway). Pubertal development of their children was assessed at a single visit at age 7-12 years (579 girls, 644 boys) using the parent-reported Pubertal Development Scale (PDS). Mixed-effect Poisson and g-computation and Bayesian Kernel Machine Regression (BKMR) were employed to examine associations of individual and combined prenatal chemical exposure, respectively, with the probability of overall pubertal onset, adrenarche, and gonadarche (stage 2+) in girls and boys. Effect modification by child body mass index (BMI) was also assessed.

RESULTS

Maternal concentrations of the molar sum of DEHP and of DiNP metabolites were associated with a slightly higher probability of having started puberty in boys (relative risk, RR [95% CI] = 1.13 [0.98-1.30] and 1.20 [1.06-1.34], respectively, for a two-fold increase in concentrations), with a stronger association for DiNP in boys with overweight or obesity. In contrast, BPA, BuPB, EtPB, and PrPB were associated with a lower probability of pubertal onset, adrenarche, and/or gonadarche in all boys (e.g. overall puberty, BPA: RR [95% CI] = 0.93 [0.85-1.01] and BuPB: 0.95 [0.90-1.00], respectively), and the association with BPA was stronger in boys with underweight/normal weight. In girls, MEHP and BPA were associated with delayed gonadarche in those with underweight/normal weight (RR [95% CI] = 0.86 [0.77-0.95] and 0.90 [0.84-0.97], respectively). Most of these associations were trimester specific. However, the chemical mixture was not associated with any pubertal outcome in boys or girls.

CONCLUSIONS

Prenatal exposure to certain phthalates and synthetic phenols such as BPA may impact the pubertal development of boys, and weight status may modify this effect. BPA may also alter the pubertal development of girls.

Liver and Pancreatic Toxicity of Endocrine-Disruptive Chemicals: Focus on Mitochondrial Dysfunction and Oxidative Stress

In recent years, the worldwide epidemic of metabolic diseases, namely obesity, metabolic syndrome, diabetes and metabolic-associated fatty liver disease (MAFLD) has been strongly associated with constant exposure to endocrine-disruptive chemicals (EDCs), in particular, the ones able to disrupt various metabolic pathways. EDCs have a negative impact on several human tissues/systems, including metabolically active organs, such as the liver and pancreas. Among their deleterious effects, EDCs induce mitochondrial dysfunction and oxidative stress, which are also the major pathophysiological mechanisms underlying metabolic diseases. In this narrative review, we delve into the current literature on EDC toxicity effects on the liver and pancreatic tissues in terms of impaired mitochondrial function and redox homeostasis.

Environmental phenol exposures in 6- to 12-week-old infants: The Infant Feeding and Early Development (IFED) study

BACKGROUND

Exposure to phenols, endocrine-disrupting chemicals used in personal care and consumer products, is widespread. Data on infant exposures are limited despite heightened sensitivity to endocrine disruption during this developmental period. We aimed to describe distributions and predictors of urinary phenol concentrations among U.S. infants ages 6-12 weeks.

METHODS

The Infant Feeding and Early Development (IFED) study is a prospective cohort study of healthy term infants enrolled during 2010-2013 in the Philadelphia region. We measured concentrations of seven phenols in 352 urine samples collected during the 6- or 8- and/or 12-week study visits from 199 infants. We used linear mixed models to estimate associations of maternal, sociodemographic, infant, and sample characteristics with natural-log transformed, creatinine-standardized phenol concentrations and present results as mean percent change from the reference level.

RESULTS

Median concentrations (μg/L) were 311 for methylparaben, 10.3 for propylparaben, 3.6 for benzophenone-3, 2.1 for triclosan, 1.0 for 2,5-dichlorophenol, 0.7 for BPA, and 0.3 for 2,4-dichlorophenol. Geometric mean methylparaben concentrations were approximately 10 times higher than published estimates for U.S. children ages 3-5 and 6-11 years, while propylparaben concentrations were 3-4 times higher. Infants of Black mothers had higher concentrations of BPA (83%), methylparaben (121%), propylparaben (218%), and 2,5-dichorophenol (287%) and lower concentrations of benzophenone-3 (-77%) and triclosan (-53%) than infants of White mothers. Triclosan concentrations were higher in breastfed infants (176%) and lower in infants whose mothers had a high school education or less (-62%). Phenol concentrations were generally higher in summer samples.

CONCLUSIONS

Widespread exposure to select environmental phenols among this cohort of healthy U.S. infants, including much higher paraben concentrations compared to those reported for U.S. children, supports the importance of expanding population-based biomonitoring programs to infants and toddlers. Future investigation of exposure sources is warranted to identify opportunities to minimize exposures during these sensitive periods of development.

Gestational exposure to environmental chemicals and epigenetic alterations in the placenta and cord blood mononuclear cells

Background

Exposure to environmental chemicals such as phthalates, phenols, and polycyclic aromatic hydrocarbons (PAHs) during pregnancy can increase the risk of adverse newborn outcomes. We explored the associations between maternal exposure to select environmental chemicals and DNA methylation in cord blood mononuclear cells (CBMC) and placental tissue (maternal and fetal sides) to identify potential mechanisms underlying these associations.

Method

This study included 75 pregnant individuals who planned to give birth at the University of Cincinnati Hospital between 2014 and 2017. Maternal urine samples during the delivery visit were collected and analyzed for 37 biomarkers of phenols (12), phthalates (13), phthalate replacements (4), and PAHs (8). Cord blood and placenta tissue (maternal and fetal sides) were also collected to measure the DNA methylation intensities using the Infinium HumanMethylation450K BeadChip. We used linear regression, adjusting for potential confounders, to assess CpG-specific methylation changes in CBMC (n = 54) and placenta [fetal (n = 67) and maternal (n = 68) sides] associated with gestational chemical exposures (29 of 37 biomarkers measured in this study). To account for multiple testing, we used a false discovery rate q-values < 0.05 and presented results by limiting results with a genomic inflation factor of 1±0.5. Additionally, gene set enrichment analysis was conducted using the Kyoto Encyclopedia of Genes and Genomics pathways.

Results

Among the 29 chemical biomarkers assessed for differential methylation, maternal concentrations of PAH metabolites (1-hydroxynaphthalene, 2-hydroxyfluorene, 4-hydroxyphenanthrene, 1-hydroxypyrene), monocarboxyisononyl phthalate, mono-3-carboxypropyl phthalate, and bisphenol A were associated with altered methylation in placenta (maternal or fetal side). Among exposure biomarkers associated with epigenetic changes, 1-hydroxynaphthalene, and mono-3-carboxypropyl phthalate were consistently associated with differential CpG methylation in the placenta. Gene enrichment analysis indicated that maternal 1-hydroxynaphthalene was associated with lipid metabolism and cellular processes of the placenta. Additionally, mono-3-carboxypropyl phthalate was associated with organismal systems and genetic information processing of the placenta.

Conclusion

Among the 29 chemical biomarkers assessed during delivery, 1-hydroxynaphthalene and mono-3-carboxypropyl phthalate were associated with DNA methylation in the placenta.

Supplementary Information

The online version contains supplementary material available at 10.1186/s43682-024-00027-7.

Regrettable Substitutes and the Brain: What Animal Models and Human Studies Tell Us about the Neurodevelopmental Effects of Bisphenol, Per- and Polyfluoroalkyl Substances, and Phthalate Replacements

In recent decades, emerging evidence has identified endocrine and neurologic health concerns related to exposure to endocrine-disrupting chemicals (EDCs), including bisphenol A (BPA), certain per- and polyfluoroalkyl compounds (PFASs), and phthalates. This has resulted in consumer pressure to remove these chemicals from the market, especially in food-contact materials and personal care products, driving their replacement with structurally or functionally similar substitutes. However, these "new-generation" chemicals may be just as or more harmful than their predecessors and some have not received adequate testing. This review discusses the research on early-life exposures to new-generation bisphenols, PFASs, and phthalates and their links to neurodevelopmental and behavioral alterations in zebrafish, rodents, and humans. As a whole, the evidence suggests that BPA alternatives, especially BPAF, and newer PFASs, such as GenX, can have significant effects on neurodevelopment. The need for further research, especially regarding phthalate replacements and bio-based alternatives, is briefly discussed.

Knowledge and beliefs of endocrine disruptors in pediatrics: all hands on deck!

Endocrine disruptors (ED) are ubiquitous pollutants, possibly implicated in chronic disease. Exposure of vulnerable populations; including neonates, infants and children; must therefore be limited. Informing parents is now a public health challenge. We conducted a quantitative cross-sectional study at the Lyon Mother and child Hospital. We used questionnaires to assess the beliefs and knowledge about ED of parents and pediatric healthcare professionals in the pediatric ward in Lyon, France. A total of 746 questionnaires were completed: 444 for professionals and 302 for parents. The majority of both populations had already heard of ED but only 10% of parents and 5% of professionals felt sufficiently informed. Professionals answered better than parents (73% vs. 60%). The main source of information was similar: media. Only 20% of professionals had read a scientific article about ED and 4% have followed a training. Environmental exposure and EDs is an increasing concern for parents but specific knowledge remains scare for parents and professionals. Specific training is needed.

Effect-directed analysis of androgenic compounds from sewage sludges in China

The safety of municipal sewage sludge has raised great concerns because of the accumulation of large-scale endocrine disrupting chemicals in the sludge during wastewater treatment. The presence of contaminants in sludge can cause secondary pollution owing to inappropriate disposal mechanisms, posing potential risks to the environment and human health. Effect-directed analysis (EDA), involving an androgen receptor (AR) reporter gene bioassay, fractionation, and suspect and nontarget chemical analysis, were applied to identify causal AR agonists in sludge; 20 of the 30 sludge extracts exhibited significant androgenic activity. Among these, the extracts from Yinchuan, Kunming, and Shijiazhuang, which held the most polluted AR agonistic activities were prepared for extensive EDA, with the dihydrotestosterone (DHT)-equivalency of 2.5 - 4.5 ng DHT/g of sludge. Seven androgens, namely boldione, androstenedione, testosterone, megestrol, progesterone, and testosterone isocaproate, were identified in these strongest sludges together, along with testosterone cypionate, first reported in sludge media. These identified androgens together accounted for 55 %, 87 %, and 52 % of the effects on the sludge from Yinchuan, Shijiazhuang, and Kunming, respectively. This study elucidates the causative androgenic compounds in sewage sludge and provides a valuable reference for monitoring and managing androgens in wastewater treatment.

Gender-specific abdominal fat distribution and insulin resistance associated with organophosphate esters and phthalate metabolites exposure

The worldwide prevalence of obesity highlights the potential contribution of endocrine-disrupting chemicals (EDCs). However, common epidemiological measures such as body mass index and waist circumference may misrepresent the intricate obesity risks these chemicals pose across genders. This study delves deeper into abdominal fat by differentiating between subcutaneous and visceral regions by analyzing data from National Health and Nutrition Examination Surveys (NHANES). We particularly investigated the gender-specific associations between organophosphorus flame-retardant metabolites (mOPFRs), phthalates (mPAEs) and accumulated fat indexes from 2536 people. Aiding by Bayesian Kernel Machine Regression (BKMR), we found while co-exposure to mOPFRs and mPAEs was linked to general and abdominal obesity across the entire and gender-specific populations, a gender-specific fat distribution emerged. For women, urinary BDCPP and MBzP were linked to an increased subcutaneous fat index (SFI) [BDCPP OR: 1.12 (95% CI: 1.03-1.21), MBzP OR: 1.09 (95% CI: 1.01-1.18)], but not to visceral fat index (VFI). These metabolites had a combined linkage with SFI, with BDCPP (weighting 22.0%) and DPHP (weighting 31.0%) being the most influential in Quantile g-computation model (qgcomp) model. In men, BCEP exposure exclusively associated with the elevated VFI [OR: 1.14 (95% CI: 1.03-1.26)], a trend further highlighted in mixture models with BCEP as the predominant association. Intriguingly, only males displayed a marked correlation between these metabolites and insulin resistance in subpopulation. An attempted mediation analysis revealed that elevated C-reactive protein mediated 12.1% of the association between urinary BCEP and insulin resistance, suggesting a potential role of inflammation. In conclusion, the gender-specific fat distribution and insulin resistance that associated with mOPFRs represented the potential risk of these chemicals to man.

8-OHdG mediates the association of co-exposure to fifty-five typical endocrine-disrupting chemicals with renal function: a cross-section investigation in Southern Chinese adults

Individual typical endocrine-disrupting chemicals (EDCs), including organophosphate triesters (OPEs), parabens, triclosan (TCS), bisphenols, benzophenones (BPs), phthalates (PAEs), and synthetic phenolic antioxidants (SPAs), are associated with renal dysfunction. However, the combined effects and underlying mechanisms of mixed EDC exposure on renal function remain unclear. Two hundred ninety-nine adult participants were enrolled in the cross-sectional survey conducted in Guangzhou, China. Urinary levels of 7 OPEs, 6 parabens, TCS, 14 bisphenols, 8 BPs, 15 PAEs, 4 SPAs, and 8-hydroxy-2'-deoxyguanosine (8-OHdG) were determined, and estimated glomerular filtration rate (eGFR) was served as the outcome index. We found elevated levels of diphenyl phosphate (DPP), bisphenol A (BPA), mono-(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP), and mono-butyl phthalate (MBP) showed dose-responsive associations with eGFR decline, However, nonlinear associations were observed for bis(2-butoxyethyl) hydrogen phosphate (BBOEP), TCS, 4-hydroxybenzophenone (HBP), mono-n-pentyl phthalate (MnPP), and mono-benzyl phthalate (MBzP). The quantile-based g-computation model demonstrated that a quartile increase in the EDC mixture corresponded to a 0.383-SD decrease (95% CI - 0.658 ~  - 0.108, P = 0.007) in eGFR. Notably, BPA was identified as the primary contributor to this effect. Moreover, 8-OHdG mediated the eGFR decline associated with EDC mixtures with a mediation proportion of 25.49%. A sex-modified effect was also observed (P = 0.004), indicating that exposure to the mixture of EDC was linked to more pronounced renal dysfunction in females. Our novel findings suggest that exposure to a typical mixture of EDCs is associated with renal dysfunction in the general adult population of Southern China. Furthermore, 8-OHdG may play a role in the pathogenesis of EDC mixture-related renal dysfunction.

Exceptionally High Perfluorooctanoic Acid Uptake in Water by a Zirconium-Based Metal-Organic Framework through Synergistic Chemical and Physical Adsorption

Perfluorooctanoic acid (PFOA) is an environmental contaminant ubiquitous in water resources, which as a xenobiotic and carcinogenic agent, severely endangers human health. The development of techniques for its efficient removal is therefore highly sought after. Herein, we demonstrate an unprecedented zirconium-based MOF (PCN-999) possessing Zr6 and biformate-bridged (Zr6)2 clusters simultaneously, which exhibits an exceptional PFOA uptake of 1089 mg/g (2.63 mmol/g), representing a ca. 50% increase over the previous record for MOFs. Single-crystal X-ray diffraction studies and computational analysis revealed that the (Zr6)2 clusters offer additional open coordination sites for hosting PFOA. The coordinated PFOAs further enhance the interaction between coordinated and free PFOAs for physical adsorption, boosting the adsorption capacity to an unparalleled high standard. Our findings represent a major step forward in the fundamental understanding of the MOF-based PFOA removal mechanism, paving the way toward the rational design of next-generation adsorbents for per- and polyfluoroalkyl substance (PFAS) removal.

The Conflict between Regulatory Agencies over the 20,000-Fold Lowering of the Tolerable Daily Intake (TDI) for Bisphenol A (BPA) by the European Food Safety Authority (EFSA)

BACKGROUND

The European Food Safety Authority (EFSA) recommended lowering their estimated tolerable daily intake (TDI) for bisphenol A (BPA) 20,000-fold to 0.2  ng / kg  body weight  ( BW ) / day . BPA is an extensively studied high production volume endocrine disrupting chemical (EDC) associated with a vast array of diseases. Prior risk assessments of BPA by EFSA as well as the US Food and Drug Administration (FDA) have relied on industry-funded studies conducted under good laboratory practice protocols (GLP) requiring guideline end points and detailed record keeping, while also claiming to examine (but rejecting) thousands of published findings by academic scientists. Guideline protocols initially formalized in the mid-twentieth century are still used by many regulatory agencies. EFSA used a 21st century approach in its reassessment of BPA and conducted a transparent, but time-limited, systematic review that included both guideline and academic research. The German Federal Institute for Risk Assessment (BfR) opposed EFSA's revision of the TDI for BPA.

OBJECTIVES

We identify the flaws in the assumptions that the German BfR, as well as the FDA, have used to justify maintaining the TDI for BPA at levels above what a vast amount of academic research shows to cause harm. We argue that regulatory agencies need to incorporate 21st century science into chemical hazard identifications using the CLARITY-BPA (Consortium Linking Academic and Regulatory Insights on BPA Toxicity) nonguideline academic studies in a collaborative government-academic program model.

DISCUSSION

We strongly endorse EFSA's revised TDI for BPA and support the European Commission's (EC) apparent acceptance of this updated BPA risk assessment. We discuss challenges to current chemical risk assessment assumptions about EDCs that need to be addressed by regulatory agencies to, in our opinion, become truly protective of public health. Addressing these challenges will hopefully result in BPA, and eventually other structurally similar bisphenols (called regrettable substitutions) for which there are known adverse effects, being eliminated from all food-related and many other uses in the EU and elsewhere. https://doi.org/10.1289/EHP13812.

Building an adverse outcome pathway network for estrogen-, androgen- and steroidogenesis-mediated reproductive toxicity

Introduction: Adverse Outcome Pathways (AOPs) can support both testing and assessment of endocrine disruptors (EDs). There is, however, a need for further development of the AOP framework to improve its applicability in a regulatory context. Here we have inventoried the AOP-wiki to identify all existing AOPs related to mammalian reproductive toxicity arising from disruption to the estrogen, androgen, and steroidogenesis modalities. Core key events (KEs) shared between relevant AOPs were also identified to aid in further AOP network (AOPN) development. Methods: A systematic approach using two different methods was applied to screen and search the entire AOP-wiki library. An AOPN was visualized using Cytoscape. Manual refinement was performed to remove AOPS devoid of any KEs and/or KERs. Results: Fifty-eight AOPs relevant for mammalian reproductive toxicity were originally identified, with 42 AOPs included in the final AOPN. Several of the KEs and KE relationships (KERs) described similar events and were thus merged to optimize AOPN construction. Sixteen sub-networks related to effects on hormone levels or hormone activity, cancer outcomes, male and female reproductive systems, and overall effects on fertility and reproduction were identified within the AOPN. Twenty-six KEs and 11 KERs were identified as core blocks of knowledge in the AOPN, of which 19 core KEs are already included as parameters in current OECD and US EPA test guidelines. Discussion: The AOPN highlights knowledge gaps that can be targeted for further development of a more complete AOPN that can support the identification and assessment of EDs.

Endocrine-disrupting chemicals: Mainstream recognition of health effects and implications for the practicing internist

Rapidly advancing evidence documents that a broad array of synthetic chemicals found ubiquitously in the environment contribute to disease and disability across the lifespan. Although the early literature focused on early life exposures, endocrine-disrupting chemicals (EDCs) are now understood to contribute substantially to chronic disease in adulthood, especially metabolic, cardiovascular, and reproductive consequences as well as endocrine cancers. The contribution to mortality is substantial, with over 90,000 deaths annually and at least $39 billion/year in lost economic productivity in the United States (US) due to exposure to certain phthalates that are used as plasticizers in food packaging. Importantly, exposures are disproportionately high in low-income and minoritized populations, driving disparities in these conditions. Though non-Hispanic Blacks and Mexican Americans comprise 12.6% and 13.5% of the US population, they bear 16.5% and 14.6% of the disease burden due to EDCs, respectively. Many of these exposures can be modified through safe and simple behavioral changes supported by proactive government action to both limit known hazardous exposures and to proactively screen new industrial chemicals prior to their use. Routine healthcare maintenance should include guidance to reduce EDC exposures, and a recent report by the Institute of Medicine suggests that testing be conducted, particularly in populations heavily exposed to perfluoroalkyl substances-chemicals used in nonstick coatings as well as oil- and water-resistant clothing.

[Disruptors of thyroid hormones: Which consequences for human health and environment?]

Endocrine disruptors (EDs) of chemical origin are the subject of numerous studies, some of which have led to measures aimed at limiting their use and their impact on the environment and human health. Dozens of hormones have been described and are common to all vertebrates (some chemically related messengers have also been identified in invertebrates), with variable roles that are not always known. The effects of endocrine disruptors therefore potentially concern all animal species via all endocrine axes. These effects are added to the other parameters of the exposome, leading to strong, multiple and complex adaptive pressures. The effects of EDs on reproductive and thyroid pathways have been among the most extensively studied over the last 30 years, in a large number of species. The study of the effects of EDs on thyroid pathways and brain development goes hand in hand with increasing knowledge of 1) the different roles of thyroid hormones at cellular or tissue level (particularly developing brain tissue) in many species, 2) other hormonal pathways and 3) epigenetic interactions. If we want to understand how EDs affect living organisms, we need to integrate results from complementary scientific fields within an integrated, multi-model approach (the so-called translational approach). In the present review article, we aim at reporting recent discoveries and discuss prospects for action in the fields of medicine and research. We also want to highlight the need for an integrated, multi-disciplinary approach to studying impacts and taking appropriate action.

Imprinting and Reproductive Health: A Toxicological Perspective

This overview discusses the role of imprinting in the development of an organism, and how exposure to environmental chemicals during fetal development leads to the physiological and biochemical changes that can have adverse lifelong effects on the health of the offspring. There has been a recent upsurge in the use of chemical products in everyday life. These chemicals include industrial byproducts, pesticides, dietary supplements, and pharmaceutical products. They mimic the natural estrogens and bind to estradiol receptors. Consequently, they reduce the number of receptors available for ligand binding. This leads to a faulty signaling in the neuroendocrine system during the critical developmental process of 'imprinting'. Imprinting causes structural and organizational differentiation in male and female reproductive organs, sexual behavior, bone mineral density, and the metabolism of exogenous and endogenous chemical substances. Several studies conducted on animal models and epidemiological studies provide profound evidence that altered imprinting causes various developmental and reproductive abnormalities and other diseases in humans. Altered metabolism can be measured by various endpoints such as the profile of cytochrome P-450 enzymes (CYP450's), xenobiotic metabolite levels, and DNA adducts. The importance of imprinting in the potentiation or attenuation of toxic chemicals is discussed.