EDC-2: The Endocrine Society's Second Scientific Statement on Endocrine-Disrupting Chemicals

An engaged research study to assess the effect of a 'real-world' dietary intervention on urinary bisphenol A (BPA) levels in teenagers

OBJECTIVE

Bisphenol A (BPA) has been associated with adverse human health outcomes and exposure to this compound is near-ubiquitous in the Western world. We aimed to examine whether self-moderation of BPA exposure is possible by altering diet in a real-world setting.

DESIGN

An Engaged Research dietary intervention study designed, implemented and analysed by healthy teenagers from six schools and undertaken in their own homes.

PARTICIPANTS

A total of 94 students aged between 17 and 19 years from schools in the South West of the UK provided diet diaries and urine samples for analysis.

INTERVENTION

Researcher participants designed a set of literature-informed guidelines for the reduction of dietary BPA to be followed for 7 days.

MAIN OUTCOME MEASURES

Creatinine-adjusted urinary BPA levels were taken before and after the intervention. Information on packaging and food/drink ingested was used to calculate a BPA risk score for anticipated exposure. A qualitative analysis was carried out to identify themes addressing long-term sustainability of the diet.

RESULTS

BPA was detected in urine of 86% of participants at baseline at a median value of 1.22 ng/mL (IQR 1.99). No effect of the intervention diet on BPA levels was identified overall (P=0.25), but there was a positive association in those participants who showed a drop in urinary BPA concentration postintervention and their initial BPA level (P=0.003). Qualitative analysis identified themes around feelings of lifestyle restriction and the inadequacy of current labelling practices.

CONCLUSIONS

We found no evidence in this self-administered intervention study that it was possible to moderate BPA exposure by diet in a real-world setting. Furthermore, our study participants indicated that they would be unlikely to sustain such a diet long term, due to the difficulty in identifying BPA-free foods.

Extranuclear-initiated estrogenic actions of endocrine disrupting chemicals: Is there toxicology beyond paracelsus?

Endocrine Disrupting Chemicals (EDCs), including bisphenol-A (BPA) do not act as traditional toxic chemicals inducing massive cell damage or death in an unspecific manner. EDCs can work upon binding to hormone receptors, acting as agonists, antagonists or modulators. Bisphenol-A displays estrogenic activity and, for many years it has been classified as a weak estrogen, based on the classic transcriptional action of estrogen receptors serving as transcription factors. However, during the last two decades our knowledge about estrogen signaling has advanced considerably. It is now accepted that estrogen receptors ERα and ERβ activate signaling pathways outside the nucleus which may or may not involve transcription. In addition, a new membrane estrogen receptor, GPER, has been proposed. Pharmacological and molecular evidence, along with results obtained in genetically modified mice, demonstrated that BPA, and its substitute BPS, are potent estrogens acting at nanomolar concentrations via extranuclear ERα, ERβ, and GPER. The different signaling pathways activated by BPA and BPS explain the well-known estrogenic effects of low doses of EDCs as well as non-monotonic dose-response relationships. These signaling pathways may help to explain the actions of EDCs with estrogenic activity in the etiology of different pathologies, including type-2 diabetes and obesity.

Endocrine Disruptors: Adverse Health Effects Mediated by EGFR?

Although endocrine disruptors represent a serious concern to human health, the underlying molecular mechanisms leading to diseases such as cancer remain poorly understood. Recent work has uncovered the epidermal growth factor receptor (EGFR) as a possible mediator of these adverse health effects, with important implications for the role of endocrine disruptors in human diseases.

Arsenic exposure induces glucose intolerance and alters global energy metabolism

Environmental pollutants acting as endocrine-disrupting chemicals (EDCs) are recognized as potential contributors to metabolic disease pathogenesis. One such pollutant, arsenic, contaminates the drinking water of ~100 million people globally and has been associated with insulin resistance and diabetes in epidemiological studies. Despite these observations, the precise metabolic derangements induced by arsenic remain incompletely characterized. In the present study, the impact of arsenic on in vivo metabolic physiology was examined in 8-wk-old male C57BL/6J mice exposed to 50 mg/l inorganic arsenite in their drinking water for 8 wk. Glucose metabolism was assessed via in vivo metabolic testing, and feeding behavior was analyzed using indirect calorimetry in metabolic cages. Pancreatic islet composition was assessed via immunofluorescence microscopy. Arsenic-exposed mice exhibited impaired glucose tolerance compared with controls; however, no difference in peripheral insulin resistance was noted between groups. Instead, early insulin release during glucose challenge was attenuated relative to the rise in glycemia. Despite decreased insulin secretion, pancreatic β-cell mass was not altered, suggesting that arsenic primarily disrupts β-cell function. Finally, metabolic cage analyses revealed that arsenic exposure induced novel alterations in the diurnal rhythm of food intake and energy metabolism. Taken together, these data suggest that arsenic exposure impairs glucose tolerance through functional impairments in insulin secretion from β-cells rather than by augmenting peripheral insulin resistance. Further elucidation of the mechanisms underlying arsenic-induced behavioral and β-cell-specific metabolic disruptions will inform future intervention strategies to address this ubiquitous environmental contaminant and novel diabetes risk factor.

Phthalate esters on urban airborne particles: Levels in PM10 and PM2.5 from Mexico City and theoretical assessment of lung exposure

Endocrine disrupting chemicals (EDCs) from the environment are associated with reproductive abnormalities (i.e. decreased sperm concentration; increased endometriosis) and alterations of the cardiovascular system (i.e. increased blood pressure and risk of coronary disease). Some phthalates esters have been identified as EDCs, for which inhalation is considered as one of the routes of exposure. However, only little is known regarding inhalational exposure to EDCs via urban airborne particles. In the present study, we report the monthly concentration of 8 phthalate esters measured in PM₁₀ and PM_2.5 collected and recovered during 7 months in a highly populated area of Mexico City. Using the levels of PM₁₀ and PM_2.5 reported by the automatized network of environmental monitoring of Mexico City for the sampling site, we estimated exposure levels for people of different ages and gender. Two endocrine disrupting compounds, the phthalate esters DEHP and DnBP, were found on the particles in higher concentrations during the warmer months of the year. The highest concentration was reported for DEHP (229.7μg/g of particles) in PM_2.5 collected in May 2013. After calculations of the DEHP concentration in the atmosphere, and using the respiratory flow rate, we determined males were potentially exposed to larger quantities of DEHP, reaching up to 18ng/8h in April 2013. Despite the concentrations of phthalates seem to be rather small, a comprehensive characterization of its presence is necessary in order to evaluate the overall exposure to these compounds, providing a clear view of exposure on children, adolescents and pregnant women.

Endocrine disrupters and pubertal timing

PURPOSE OF REVIEW

The current review summarizes recent epidemiologic data demonstrating the effects of endocrine disrupting compounds (EDCs) on the timing of puberty and highlights the complexity of understanding the interplay of environmental and genetic factors on pubertal timing.

RECENT FINDINGS

In girls, there have been mixed results, with some exposures being associated with earlier timing of puberty, and some with later puberty. In boys, prepubertal exposures to nondioxin-like polychlorinated biphenyls accelerate puberty, whereas levels of insecticides, dioxin-like compounds, organochlorine pesticides, and lead delay puberty.

SUMMARY

The effects of EDCs on pubertal timing are sexually dimorphic, compound specific, and varies according to the window of exposure. These studies confirm that low-level exposures to a mix of environmental compounds may mask the effects of individual compounds and complicate our ability to translate data from animal studies to human health and to fully understand the clinical implications of environmental epidemiology studies.

High-throughput in Vitro Data To Inform Prioritization of Ambient Water Monitoring and Testing for Endocrine Active Chemicals

The presence of industrial chemicals, consumer product chemicals, and pharmaceuticals is well documented in waters in the U.S. and globally. Most of these chemicals lack health-protective guidelines and many have been shown to have endocrine bioactivity. There is currently no systematic or national prioritization for monitoring waters for chemicals with endocrine disrupting activity. We propose ambient water bioactivity concentrations (AWBCs) generated from high throughput data as a health-based screen for endocrine bioactivity of chemicals in water. The U.S. EPA ToxCast program has screened over 1800 chemicals for estrogen receptor (ER) and androgen receptor (AR) pathway bioactivity. AWBCs are calculated for 110 ER and 212 AR bioactive chemicals using high throughput ToxCast data from in vitro screening assays and predictive pathway models, high-throughput toxicokinetic data, and data-driven assumptions about consumption of water. Chemical-specific AWBCs are compared with measured water concentrations in data sets from the greater Denver area, Minnesota lakes, and Oregon waters, demonstrating a framework for identifying endocrine bioactive chemicals. This approach can be used to screen potential cumulative endocrine activity in drinking water and to inform prioritization of future monitoring, chemical testing and pollution prevention efforts.

Hair product use, age at menarche and mammographic breast density in multiethnic urban women

BACKGROUND

Select hair products contain endocrine disrupting chemicals (EDCs) that may affect breast cancer risk. We hypothesize that, if EDCs are related to breast cancer risk, then they may also affect two important breast cancer risk factors: age at menarche and mammographic breast density.

METHODS

In two urban female cohorts (N = 248): 1) the New York site of the National Collaborative Perinatal Project and 2) the New York City Multiethnic Breast Cancer Project, we measured childhood and adult use of hair oils, lotions, leave-in conditioners, root stimulators, perms/relaxers, and hair dyes using the same validated questionnaire. We used multivariable relative risk regression models to examine the association between childhood hair product use and early age at menarche (defined as <11 years of age) and multivariable linear regression models to examine the association between childhood and adult hair product use and adult mammographic breast density.

RESULTS

Early menarche was associated with ever use of childhood hair products (RR 2.3, 95% CI 1.1, 4.8) and hair oil use (RR 2.5, 95% CI 1.2, 5.2); however, additional adjustment for race/ethnicity, attenuated associations (hair products RR 1.8, 95% CI 0.8, 4.1; hair oil use RR 2.3, 95% CI 1.0, 5.5). Breast density was not associated with adult or childhood hair product or hair oil use.

CONCLUSIONS

If confirmed in larger prospective studies, these data suggest that exposure to EDCs through hair products in early life may affect breast cancer risk by altering timing of menarche, and may operate through a mechanism distinct from breast density.

Evidence for estrogeno-mimetic effects of a mixture of low-dose pollutants in a model of ovariectomized mice

We recently hypothesized that a mixture of low-dosed dioxin, polychlorobiphenyl, phthalate and bisphenol may induce estrogeno-mimetic activities in a model of lifelong-exposed female mice. Herein, we evaluated the impact of this mixture in estrogen deficiency conditions. Based on the protective effects of estrogens against metabolic disorders, we reasoned that exposure to pollutants should attenuate the deleterious metabolic effects induced by ovariectomy. In line with the hypothesis, exposure to pollutants was found to reduce the impact of ovariectomy on glucose intolerance and insulin resistance, to enhance the expression levels of the hepatic estrogen receptor α and to attenuate the ovariectomy-induced enhancement of the chemokine MCP-1/CCL2 considered as an indicator of estrogen signalling. Because of the very low doses of pollutants used in mixture, these findings may have strong implications in terms of understanding the potential role of environmental contaminants in the development of metabolic diseases, specifically in females during menopausal transition.

Marine litter plastics and microplastics and their toxic chemicals components: the need for urgent preventive measures

Persistent plastics, with an estimated lifetime for degradation of hundreds of years in marine conditions, can break up into micro- and nanoplastics over shorter timescales, thus facilitating their uptake by marine biota throughout the food chain. These polymers may contain chemical additives and contaminants, including some known endocrine disruptors that may be harmful at extremely low concentrations for marine biota, thus posing potential risks to marine ecosystems, biodiversity and food availability. Although there is still need to carry out focused scientific research to fill the knowledge gaps about the impacts of plastic litter in the marine environment (Wagner et al. in Environ Sci Eur 26:9, 2014), the food chain and human health, existing scientific evidence and concerns are already sufficient to support actions by the scientific, industry, policy and civil society communities to curb the ongoing flow of plastics and the toxic chemicals they contain into the marine environment. Without immediate strong preventive measures, the environmental impacts and the economic costs are set only to become worse, even in the short term. Continued increases in plastic production and consumption, combined with wasteful uses, inefficient waste collection infrastructures and insufficient waste management facilities, especially in developing countries, mean that even achieving already established objectives for reductions in marine litter remains a huge challenge, and one unlikely to be met without a fundamental rethink of the ways in which we consume plastics. This document was prepared by a working group of Regional Centres of the Stockholm and Basel Conventions and related colleagues intended to be a background document for discussion in the 2017 Conference of the Parties (COP) of the Basel Convention on hazardous wastes and the Stockholm Convention on persistent organic pollutants (POPs). The COP finally approved that the issue of plastic waste could be dealt by its Regional Centres and consistently report their activities on the matter to next COP's meetings.

Developmental Exposure to Endocrine Disrupting Chemicals and Type 1 Diabetes Mellitus

Exposure to endocrine disrupting chemicals (EDCs) may have implications for the development of type 1 diabetes mellitus (T1DM), especially if exposure occurs during development. Exposure to EDCs during fetal or early life can disrupt the development of both the immune system and the pancreatic beta cells, potentially increasing susceptibility to T1DM later in life. Developmental exposure to some EDCs can cause immune system dysfunction, increasing the risk of autoimmunity. In addition, developmental exposure to some EDCs can affect beta cell development and function, influencing insulin secretion. These changes may increase stress on the beta cells, and identify them as a target to the immune system. Developmental exposure to EDCs that disrupt metabolism by increasing insulin resistance or obesity may also stress the beta cells. Exposure to these EDCs during development may play a role in the pathogenesis of T1DM, and requires further research.

Endocrine Disruptors and Developmental Origins of Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is a growing epidemic worldwide, particularly in countries that consume a Western diet, and can lead to life-threatening conditions such as cirrhosis and hepatocellular carcinoma. With increasing prevalence of NAFLD in both children and adults, an understanding of the factors that promote NAFLD development and progression is crucial. Environmental agents, including endocrine-disrupting chemicals (EDCs), which have been linked to other diseases, may play a role in NAFLD development. Increasing evidence supports a developmental origin of liver disease, and early-life exposure to EDCs could represent one risk factor for the development of NAFLD later in life. Rodent studies provide the strongest evidence for this link, but further studies are needed to define whether there is a causal link between early-life EDC exposure and NAFLD development in humans. Elucidating the molecular mechanisms underlying development of NAFLD in the context of developmental EDC exposures may identify biomarkers for people at risk, as well as potential intervention and/or therapeutic opportunities for the disease.

Environmental Pollutants and Metabolic Disorders: The Multi-Exposure Scenario of Life

Obesity and diabetes have reached epidemic proportions the past few decades and continue to progress worldwide with no clear sign of decline of the epidemic. Obesity is of high concern because it is the main risk factor for a number of non-communicable diseases such as cardiovascular diseases and type 2 diabetes. Metabolic diseases constitute a major challenge as they are associated with an overall reduced quality of life and impose a heavy economic burden on countries. These are multifactorial diseases and it is now recognized that environmental exposure to man-made chemical pollutants is part of the equation. Yet, risk assessment procedures are based on a one-by-one chemical evaluation which does not meet the specificities of the multi-exposure scenario of life, e.g., a combined and long-term exposure to even the smallest amounts of chemicals. Indeed, it is assumed that environmental exposure to chemicals will be negligible based on the low potency of each chemical and that they do not interact. Within this mini-review, strong evidences are brought that exposure to low levels of multiple chemicals especially those shown to interfere with hormonal action, the so-called endocrine disrupting compounds do trigger metabolic disturbances in conditions in which no effect was expected if considering the concentration of each individual chemical in the mixture. This is known as the cocktail effect. It means that risk assessment procedures are not protective enough and thus that it should be revisited for the sake of Public Health.

Immune System: An Emerging Player in Mediating Effects of Endocrine Disruptors on Metabolic Health

The incidence of metabolic disorders like type 2 diabetes and obesity continues to increase. In addition to the well-known contributors to these disorders, such as food intake and sedentary lifestyle, recent research in the exposure science discipline provides evidence that exposure to endocrine-disrupting chemicals like bisphenol A and phthalates via multiple routes (e.g., food, drink, skin contact) also contribute to the increased risk of metabolic disorders. Endocrine-disrupting chemicals (EDCs) can disrupt any aspect of hormone action. It is becoming increasingly clear that EDCs not only affect endocrine function but also adversely affect immune system function. In this review, we focus on human, animal, and in vitro studies that demonstrate EDC exposure induces dysfunction of the immune system, which, in turn, has detrimental effects on metabolic health. These findings highlight how the immune system is emerging as a novel player by which EDCs may mediate their effects on metabolic health. We also discuss studies highlighting mechanisms by which EDCs affect the immune system. Finally, we consider that a better understanding of the immunomodulatory roles of EDCs will provide clues to enhance metabolic function and contribute toward the long-term goal of reducing the burden of environmentally induced diabetes and obesity.

Prenatal exposure to di(2-ethylhexyl) phthalate disrupts ovarian function in a transgenerational manner in female mice

Di(2-ethylhexyl) phthalate (DEHP) is a plasticizer found in polyvinyl chloride products such as vinyl flooring, plastic food containers, medical devices, and children's toys. DEHP is a ubiquitous environmental contaminant and is a known endocrine disrupting chemical. Little is known about the effects of prenatal DEHP exposure on the ovary and whether effects occur in subsequent generations. Thus, we tested the hypothesis that prenatal exposure to DEHP disrupts ovarian functions in the F1, F2, and F3 generations of female mice. To test this hypothesis, pregnant CD-1 mice were orally dosed with corn oil (vehicle control) or DEHP (20 and 200 μg/kg/day and 200, 500, and 750 mg/kg/day) daily from gestation day 10.5 until birth (7-28 dams/treatment group). F1 females were mated with untreated males to obtain the F2 generation, and F2 females were mated with untreated males to produce the F3 generation. On postnatal days 1, 8, 21, and 60, ovaries were collected and used for histological evaluation of follicle numbers and sera were used to measure progesterone, testosterone, 17β-estradiol, luteinizing hormone, and follicle stimulating hormone levels. In the F1 generation, prenatal exposure to DEHP disrupted body and organ weights, decreased folliculogenesis, and increased serum 17β-estradiol levels. In the F2 generation, exposure to DEHP decreased body and organ weights, dysregulated folliculogenesis, and disrupted serum progesterone levels. In the F3 generation, DEHP exposure accelerated folliculogenesis. These data suggest that prenatal exposure to DEHP leads to adverse multigenerational and transgenerational effects on ovarian function.

Giant toads (Rhinella marina) living in agricultural areas have altered spermatogenesis

Across diverse taxa, germ cell development is controlled by an intricate cascade of processes that are tightly controlled by the hypothalamic-pituitary-gonadal axis. Endocrine disturbances, such as those induced by endocrine disrupting chemicals (EDCs) can negatively affect spermatogenesis. Here, we investigate whether spermatogenesis is altered in the giant toad, Rhinella marina, living in agricultural areas where EDCs are used relative to suburban areas. We also ask if reductions in spermatogenesis were associated with developmental gonadal abnormalities (intersex) found in the same frogs. We found that toads in agricultural areas exhibited reduced spermatogenesis relative to non-agricultural animals, and that those reductions were not associated with gross gonadal abnormalities. All toads living in agricultural areas had reduced spermatogenesis relative to those living in non-agricultural areas regardless of whether they had gonadal abnormalities originating during development. Similarities in reproductive dysfunction among diverse taxa living in agricultural areas, including humans, suggest that many vertebrate taxa living in agricultural areas around the globe are likely experiencing some level of reproductive dysfunction.

When enough data are not enough to enact policy: The failure to ban chlorpyrifos

Strong evidence now supports the notion that organophosphate pesticides damage the fetal brain and produce cognitive and behavioral dysfunction through multiple mechanisms, including thyroid disruption. A regulatory ban was proposed, but actions to end the use of one such pesticide, chlorpyrifos, in agriculture were recently stopped by the Environmental Protection Agency under false scientific pretenses. This manuscript describes the costs and consequences of this policy failure and notes how this case study is emblematic of a broader dismissal of scientific evidence and attacks on scientific norms. Scientists have a responsibility to rebut and decry these serious challenges to human health and scientific integrity.

Postnatal separation prevents the development of prenatal stress-induced anxiety in association with changes in oestrogen receptor and oxytocin immunoreactivity in female mandarin vole (Microtus mandarinus) offspring

Oestrogen has both anxiogenic and anxiolytic effects because of variation in opposing action on alpha (ERα) and beta (ERβ) estrogen receptors in the medial preoptic area (mPOA), bed nucleus of the stria terminalis (BNST) and medial amygdala (MeA). Oxytocin (OT) reverses some of the anxiogenic effects of oestrogen in the hypothalamic paraventricular nucleus (PVN) and supraoptic nucleus (SON). Because anxiety disorders are twice as common in women as in men, and oestrogen and OT are more important in females, we examined interactions between prenatal restraint stress (GS) and postnatal early short-term maternal separation (MS) and female mandarin vole behaviour, estrogen receptors and OT. The results show that adult female offspring from GS/noMS mothers showed increased anxiety in open-field and elevated plus-maze tests and had lower serum 17-beta-oestradiol (E₂ ) levels than female offspring from GS/MS, noGS/MS and noGS/noMS mothers. GS/noMS females had more immunoreactive neurons for ERα in several brain regions and less ERβ- and OT-immunoreactive neurons in brain areas compared to GS/MS, noGS/MS and noGS/noMS offspring. Interestingly, noGS/MS and GS/MS offspring were similar to noGS/noMS offspring in that they did not develop anxiety as adults. We propose that MS alters the serum concentration of E₂ and that the ERβ/ERα ratio and OT level in the brain may be responsible for the decrease in anxiety-like behaviour in adult female offspring initially exposed to anxiety-inducing conditions via an adverse foetal environment.

Estrogen, through estrogen receptor 1, regulates histone modifications and chromatin remodeling during spermatogenesis in adult rats

Estrogen receptors (ESR1 and ESR2) play crucial roles in various processes during spermatogenesis. To elucidate individual roles of ESRs in male fertility, we developed in vivo selective ESR agonist administration models. Adult male rats treated with ESR1 and ESR2 agonist for 60 days show spermatogenic defects leading to reduced sperm counts and fertility. While studying epigenetic changes in the male germ line that could have affected fertility, we earlier observed a decrease in DNA methylation and its machinery upon ESR2 agonist treatment. Here, we explored the effects on histone modifications, which could contribute to decreased male fertility upon ESR agonist administration. ESR1 agonist treatment affected testicular levels of histone modifications associated with active and repressed chromatin states, along with heterochromatin marks. This was concomitant with deregulation of corresponding histone modifying enzymes in the testis. In addition, there was increased retention of histones along with protamine deficiency in the caudal spermatozoa after ESR1 agonist treatment. This could be due to the observed decrease in several chromatin remodeling proteins implicated in mediating histone-to-protamine exchange during spermiogenesis. The activating and repressing histone marks in spermatozoa, which play a critical role in early embryo development, were deregulated after both the ESR agonist treatments. Together, these epigenetic defects in the male germ line could affect the spermatozoa quality and lead to the observed decrease in fertility. Our results thus highlight the importance of ESRs in regulating different epigenetic processes during spermatogenesis, which are crucial for male fertility.

Xenoestrogen regulation of ERα/ERβ balance in hormone-associated cancers

The hormone 17β-estradiol (E2) contributes to body homeostasis maintenance by regulating many different physiological functions in both male and female organs. E2 actions in reproductive and non-reproductive tissues rely on a complex net of nuclear and extra-nuclear signal transduction pathways triggered by at least two estrogen receptor subtypes (ERα and ERβ). Consequently, the de-regulation of E2:ER signaling contributes to the pathogenesis of many diseases including cancer. Among other factors, the ERα/ERβ ratio is considered one of the pivotal mechanisms at the root of E2 action in cancer progression. Remarkably, several natural or synthetic exogenous chemicals, collectively called xenoestrogens, bind to ERs and interfere with their signals and intracellular functions. In this review, the molecular mechanism(s) through which xenoestrogens influence ERα and ERβ intracellular concentrations and the consequences of this influence on E2-related cancer will be discussed.

Calculation of the disease burden associated with environmental chemical exposures: application of toxicological information in health economic estimation

Calculation of costs and the Burden of Disease (BoD) is useful in developing resource allocation and prioritization strategies in public and environmental health. While useful, the Disability-Adjusted Life Year (DALY) metric disregards subclinical dysfunctions, adheres to stringent causal criteria, and is hampered by gaps in environmental exposure data, especially from industrializing countries. For these reasons, a recently calculated environmental BoD of 5.18% of the total DALYs is likely underestimated. We combined and extended cost calculations for exposures to environmental chemicals, including neurotoxicants, air pollution, and endocrine disrupting chemicals, where sufficient data were available to determine dose-dependent adverse effects. Environmental exposure information allowed cost estimates for the U.S. and the EU, for OECD countries, though less comprehensive for industrializing countries. As a complement to these health economic estimations, we used attributable risk valuations from expert elicitations to as a third approach to assessing the environmental BoD. For comparison of the different estimates, we used country-specific monetary values of each DALY. The main limitation of DALY calculations is that they are available for few environmental chemicals and primarily based on mortality and impact and duration of clinical morbidity, while less serious conditions are mostly disregarded. Our economic estimates based on available exposure information and dose-response data on environmental risk factors need to be seen in conjunction with other assessments of the total cost for these environmental risk factors, as our estimate overlaps only slightly with the previously estimated environmental DALY costs and crude calculations relying on attributable risks for environmental risk factors. The three approaches complement one another and suggest that environmental chemical exposures contribute costs that may exceed 10% of the global domestic product and that current DALY calculations substantially underestimate the economic costs associated with preventable environmental risk factors. By including toxicological and epidemiological information and data on exposure distributions, more representative results can be obtained from utilizing health economic analyses of the adverse effects associated with environmental chemicals.

Heavy metals in the volcanic environment and thyroid cancer

In the last two decades thyroid cancer incidence has increased worldwide more than any other cancer. Overdiagnosis of subclinical microcarcinomas has certainly contributed to this increase but many evidences indicate that a true increase, possibly due to environmental factors, has also occurred. Thyroid cancer incidence is markedly increased in volcanic areas. Thus, the volcanic environment is a good model to investigate the possible factors favoring thyroid cancer. In the volcanic area of Mt. Etna in Sicily, as well as in other volcanic areas, a non-anthropogenic pollution with heavy metals has been documented, a consequence of gas, ash and lava emission. Soil, water and atmosphere contamination, via the food chain, biocontaminate the residents as documented by high levels in the urines and the scalp hair compared to individuals living in adjacent non-volcanic areas. Trace amounts of metals are essential nutrients but, at higher concentrations, can be toxic for living cells. Metals can behave both as endocrine disruptors, perturbing the hormonal system, and as carcinogens, promoting malignant transformation. Similarly to other carcinogens, the transforming effect of heavy metals is higher in developing organisms as the fetus (contaminated via the mother) and individuals in early childhood. In the last decades environment metal pollution has greatly increased in industrialized countries. Although still within the "normal" limits for each single metal the hormesis effect (heavy metal activity at very low concentration because of biphasic, non linear cell response) and the possible potentiation effect resulting from the mixture of different metals acting synergistically can explain cell damage at very low concentrations. The effect of metals on the human thyroid is poorly studied: for some heavy metals no data are available. The scarce studies that have been performed mainly focus on metal effect as thyroid endocrine disruptors. The metal concentration in tissues has been rarely measured in the thyroid. Heavy metal accumulation and metabolism in the thyroid or the carcinogenic activity of different doses and different speciation of metals has not been investigated. These studies are now warranted to better understand thyroid biology and heavy metal role in human thyroid carcinogenesis.

Prenatal phthalate exposure and language development in toddlers from the Odense Child Cohort

BACKGROUND

Phthalates are a group of chemicals found in a variety of consumer products. They have anti-androgenic properties and human studies have reported associations between prenatal phthalate exposure and neuropsychological development in the offspring despite different cognitive tests, different ages and varying timing of exposure.

OBJECTIVES

To investigate the association between prenatal phthalate exposure and language development in children aged 20-36months.

METHODS

In the Odense Child Cohort, we analyzed 3rd trimester urine samples of 518 pregnant women for content of metabolites of diethyl, di-n-butyl, diisobutyl, butylbenzyl, di(2-ethylhexyl), and diisononyl phthalate, adjusted for osmolality. Language development was addressed using the Danish version of the MacArthur-Bates Communicative Development Inventories "Words and Sentences". Associations were assessed using logistic regression models comparing children below and above the 15th percentile while stratifying by sex and adjusting for maternal age and educational level.

RESULTS

Phthalate metabolites were detectable in all samples although in lower levels than previous studies. Among boys, increased prenatal phthalate exposure was associated with lower scores in language development; odds ratios for vocabulary score below the 15th percentile with doubling in monoethyl phthalate, and summed di-(2-ethylhexyl) phthalate metabolites were respectively 1.24 (95% confidence interval: 1.05,1.46), and 1.33 (1.01,1.75). Similar associations were found for language complexity. No associations were found for girls.

CONCLUSIONS

Our findings are notable, as adverse associations were suggested even in this low-level exposed population, with only one spot urine sample for exposure assessment and control for confounders. Lower scores in early language development are of relevance to health as this test predicts later educational success.

Childhood obesity and endocrine disrupting chemicals

The prevalence of obesity around the world has increased sharply. Strong evidence has emerged over the last decades that human exposure to numerous endocrine disrupting chemicals (EDCs) is the cause of obesity and obesity-related metabolic diseases. Many EDCs are manmade chemicals that are released into the environment. EDCs are exogenous compounds that interfere with hormonal regulation and normal endocrine systems, thereby affecting the health of animals and humans. The number of chemicals belonging to EDCs is increasing and some of them are very stable; they persist in the environment (persistent organic pollutants). Although they are banned, their concentrations have been continuously increasing over time. This review gives a brief introduction to common EDCs, and evidence of harmful effects of EDCs on obesity-related diseases; we focus in particular on EDCs' role in causing mitochondrial dysfunction.

'Omics' and endocrine-disrupting chemicals - new paths forward

The emerging field of omics - large-scale data-rich biological measurements of the genome - provides new opportunities to advance and strengthen research into endocrine-disrupting chemicals (EDCs). Although some EDCs have been associated with adverse health effects in humans, our understanding of their impact remains incomplete. Progress in the field has been primarily limited by our inability to adequately estimate and characterize exposure and identify sensitive and measurable outcomes during windows of vulnerability. Evolving omics technologies in genomics, epigenomics and mitochondriomics have the potential to generate data that enhance exposure assessment to include the exposome - the totality of the lifetime exposure burden - and provide biology-based estimates of individual risks. Applying omics technologies to expand our knowledge of individual risk and susceptibility will augment biological data in the prediction of variability and response to disease, thereby further advancing EDC research. Together, refined exposure characterization and enhanced disease-risk prediction will help to bridge crucial gaps in EDC research and create opportunities to move the field towards a new vision - precision public health.

Low-Level Prenatal Toxin Exposures and Breastfeeding Duration: A Prospective Cohort Study

Introduction Maternal exposure to tobacco smoke is associated with shortened breastfeeding duration, but few studies have examined the effects on breastfeeding outcomes of low level exposures to other toxic chemicals. Moreover, it is unclear if passive smoking is associated with duration of breastfeeding. Our objective was therefore to examine the effect of low-level prenatal exposures to common environmental toxins (tobacco smoke, lead, and phthalates) on breastfeeding exclusivity and duration. Methods We conducted an analysis of data from the Health Outcomes and Measures of the Environment (HOME) Study. Serum and urine samples were collected at approximately 16 and 26 weeks gestation and at delivery from 373 women; 302 breastfed their infants. Maternal infant feeding interviews were conducted a maximum of eight times through 30 months postpartum. The main predictor variables for this study were gestational exposures to tobacco smoke (measured by serum cotinine), lead, and phthalates. Passive smoke exposure was defined as cotinine levels of 0.015-3.0 μg/mL. Primary outcomes were duration of any and exclusive breastfeeding. Results Serum cotinine concentrations were negatively associated with the duration of any breastfeeding (29.9 weeks unexposed vs. 24.9 weeks with passive exposure, p = 0.04; and 22.4 weeks with active exposure, p = 0.12; p = 0.03 for linear trend), but not duration of exclusive breastfeeding. Prenatal levels of blood lead and urinary phthalate metabolites were not significantly associated with duration of any or exclusive breastfeeding. Conclusions Passive exposure to tobacco smoke during pregnancy was associated with shortened duration of any breastfeeding.

Thyroid Disrupting Chemicals

Endocrine disruptor compounds are exogenous agents able to interfere with a gland function, exerting their action across different functional passages, from the synthesis to the metabolism and binding to receptors of the hormone produced. Several issues, such as different levels and time of exposure and different action across different ages as well as gender, make the study of endocrine disruptors still a challenge. The thyroid is very sensitive to the action of disruptors, and considering the importance of a correct thyroid function for physical and cognitive functioning, addressing this topic should be considered a priority. In this review, we examined the most recent studies, many of them concentrating on maternal and child exposure, conducted to assess the impact of industrial chemicals which showed an influence on thyroid function. So far, the number of studies conducted on that topic is not sufficient to provide solid conclusions and lead to homogeneous guidelines. The lack of uniformity is certainly due to differences in areas and populations examined, the different conditions of exposures and the remarkable inter-subject variability. Nonetheless, the European Commission for Health and Food Safety is implementing recommendations to ensure that substances identified as endocrine disruptors will be withdrawn from the market.

Multiple-stressor effects in an apex predator: combined influence of pollutants and sea ice decline on lipid metabolism in polar bears

There is growing evidence from experimental and human epidemiological studies that many pollutants can disrupt lipid metabolism. In Arctic wildlife, the occurrence of such compounds could have serious consequences for seasonal feeders. We set out to study whether organohalogenated compounds (OHCs) could cause disruption of energy metabolism in female polar bears (Ursus maritimus) from Svalbard, Norway (n = 112). We analyzed biomarkers of energy metabolism including the abundance profiles of nine lipid-related genes, fatty acid (FA) synthesis and elongation indices in adipose tissue, and concentrations of lipid-related variables in plasma (cholesterol, high-density lipoprotein, triglycerides). Furthermore, the plasma metabolome and lipidome were characterized by low molecular weight metabolites and lipid fingerprinting, respectively. Polychlorinated biphenyls, chlordanes, brominated diphenyl ethers and perfluoroalkyl substances were significantly related to biomarkers involved in lipid accumulation, FA metabolism, insulin utilization, and cholesterol homeostasis. Moreover, the effects of pollutants were measurable at the metabolome and lipidome levels. Our results indicate that several OHCs affect lipid biosynthesis and catabolism in female polar bears. Furthermore, these effects were more pronounced when combined with reduced sea ice extent and thickness, suggesting that climate-driven sea ice decline and OHCs have synergistic negative effects on polar bears.

Reproductive Impacts of Endocrine-Disrupting Chemicals on Wildlife Species: Implications for Conservation of Endangered Species

Wildlife have proven valuable to our understanding of the potential effects of endocrine-disrupting chemicals (EDCs) on human health by contributing considerably to our understanding of the mechanisms and consequences of EDC exposure. But the threats EDCs present to populations of wildlife species themselves are significant, particularly for endangered species whose existence is vulnerable to any reproductive perturbation. However, few studies address the threats EDCs pose to endangered species owing to challenges associated with their study. Here, we highlight those barriers and review the available literature concerning EDC effects on endangered species. Drawing from other investigations into nonthreatened wildlife species, we highlight opportunities for new approaches to advance our understanding and potentially mitigate the effects of EDCs on endangered species to enhance their fertility.

Resveratrol supports and alpha-naphthoflavone disrupts growth of human ovarian follicles in an in vitro tissue culture model

Infertility is a global health problem with an estimated incidence of 15%. Exposure to chemicals is a potential causal factor, and there is a lack of studies examining the effects on female germ cells. Here, we have studied the impact of different aryl hydrocarbon receptor (AHR) modulators on human ovarian follicles using a human ovarian tissue culture model. Expression of AHR was analyzed in tissue samples, and effects of the selected ligands resveratrol (RSVL), 6-formylindolo(3,2-b)carbazole (FICZ), and alpha-naphthoflavone (aNF) on AHR transactivation studied in a granulosa cell tumor line. Cortical human ovarian tissue containing preantral follicles was exposed to the ligands or vehicle (dimethylsulfoxide, DMSO) for seven days in vitro. Follicle growth was assessed by counting and measuring follicles from serial tissue sections, cell death quantified using in situ Terminal deoxynucleotidyl transferase dUTP Nick-End Labeling (TUNEL) assay, and steroid hormone production measured using a newly developed ultra-performance liquid chromatography method. AHR was expressed in all donated ovarian tissue samples. FICZ induced AHR transactivation in the granulosa cell line while aNF antagonised it. Compared to DMSO control, FICZ had no effect on follicles in culture, RSVL increased the proportion of growing follicles, and aNF increased cell death, disrupted growth of secondary follicles, increased testosterone, and reduced estradiol levels. We conclude that RSVL supports and aNF disrupts growth of human ovarian follicles in culture. We further conclude that the human ovarian tissue culture model is suitable for studying effects of chemicals on follicular biology.

Acute Toxicity, Teratogenic, and Estrogenic Effects of Bisphenol A and Its Alternative Replacements Bisphenol S, Bisphenol F, and Bisphenol AF in Zebrafish Embryo-Larvae

Bisphenol A (BPA), a chemical incorporated into plastics and resins, has estrogenic activity and is associated with adverse health effects in humans and wildlife. Similarly structured BPA analogues are widely used but far less is known about their potential toxicity or estrogenic activity in vivo. We undertook the first comprehensive analysis on the toxicity and teratogenic effects of the bisphenols BPA, BPS, BPF, and BPAF in zebrafish embryo-larvae and an assessment on their estrogenic mechanisms in an estrogen-responsive transgenic fish Tg(ERE:Gal4ff)(UAS:GFP). The rank order for toxicity was BPAF > BPA > BPF > BPS. Developmental deformities for larval exposures included cardiac edema, spinal malformation, and craniofacial deformities and there were distinct differences in the effects and potencies between the different bisphenol chemicals. These effects, however, occurred only at concentrations between 1.0 and 200 mg/L which exceed those in most environments. All bisphenol compounds induced estrogenic responses in Tg(ERE:Gal4ff)(UAS:GFP) zebrafish that were inhibited by coexposure with ICI 182 780, demonstrating an estrogen receptor dependent mechanism. Target tissues included the heart, liver, somite muscle, fins, and corpuscles of Stannius. The rank order for estrogenicity was BPAF > BPA = BPF > BPS. Bioconcentration factors were 4.5, 17.8, 5.3, and 0.067 for exposure concentrations of 1.0, 1.0, 0.10, and 50 mg/L for BPA, BPF, BPAF, and BPS, respectively. We thus show that these BPA alternatives induce similar toxic and estrogenic effects to BPA and that BPAF is more potent than BPA, further highlighting health concerns regarding the use of BPA alternatives.

Effects of bisphenol A treatment during pregnancy on kidney development in mice: a stereological and histopathological study

Bisphenol A (BPA) is a chemical found in plastics that resembles oestrogen in organisms. Developmental exposure to endocrine-disrupting chemicals, such as BPA, increases the susceptibility to type 2 diabetes (T2DM) and cardiovascular diseases. Animal studies have reported a nephron deficit in offspring exposed to maternal diabetes. The aim of this study was to investigate the prenatal BPA exposure effects on nephrogenesis in a mouse model that was predisposed to T2DM. This study quantitatively evaluated the renal structural changes using stereology and histomorphometry methods. The OF1 pregnant mice were treated with a vehicle or BPA (10 or 100 μg/kg/day) during days 9-16 of gestation (early nephrogenesis). The 30-day-old offspring were sacrificed, and tissue samples were collected and prepared for histopathological and stereology studies. Glomerular abnormalities and reduced glomerular formation were observed in the BPA offspring. The kidneys of the BPA10 and BPA100 female offspring had a significantly lower glomerular number and density than those of the CONTROL female offspring. The glomerular histomorphometry revealed a significant difference between the female and male CONTROL offspring for the analysed glomerular parameters that disappeared in the BPA10 and BPA100 offspring. In addition, the kidney histopathological examination showed typical male cuboidal epithelial cells of the Bowman capsule in the female BPA offspring. Exposure to environmentally relevant doses of BPA during embryonic development altered nephrogenesis. These structural changes could be associated with an increased risk of developing cardiometabolic diseases later in life.

Low-dose developmental exposure to bisphenol A induces sex-specific effects in bone of Fischer 344 rat offspring

BACKGROUND

Bisphenol A (BPA) is a component of polycarbonate plastics to which humans are regularly exposed at low levels, and an endocrine disruptor with effects on several hormonal systems. Bone is a sensitive hormone target tissue, and we have recently shown that in utero and lactational exposure to 25µg BPA/kg BW/day alters femoral geometry in rat offspring.

OBJECTIVE

To investigate bone effects in rat offspring after developmental exposure to a BPA dose in the range of human daily exposure (0.1-1.5µg/kg BW/day) as well as a dose to corroborate previous findings.

METHODS

Pregnant Fischer 344 rats were exposed to BPA via drinking water corresponding to 0.5µg/kg BW/day: [0.5], (n=21) or 50µg/kg BW/day: [50], (n = 16) from gestational day 3.5 until postnatal day 22, while controls were given only vehicle (n = 25). The offspring was sacrificed at 5 weeks of age. Bone effects were analyzed using peripheral quantitative computed tomography (pQCT), the 3-point bending test, plasma markers of bone turnover, and gene expression in cortical bone and bone marrow.

RESULTS

Compared to controls, male offspring developmentally exposed to BPA had shorter femurs. pQCT analysis revealed effects in the [0.5] group, but not in the [50] group; BPA reduced both trabecular area (-3.9%, p < 0.01) and total cross sectional area (-4.1%, p < 0.01) of femurs in the [0.5] group, whereas no effects were seen on bone density. Conversely, bone length and size were not affected in female offspring. However, the procollagen type I N-terminal propeptide (P1NP), a peptide formed during type 1 collagen synthesis, was increased in plasma (42%: p < 0.01) in female offspring exposed to [0.5] of BPA, although collagen gene expression was not increased in bone. The biomechanical properties of the bones were not altered in either sex. Bone marrow mRNA expression was only affected in male offspring.

CONCLUSIONS

Developmental low-dose exposure to BPA resulted in sex-specific bone effects in rat offspring. A dose approximately eight times lower than the current temporary EFSA human tolerable daily intake of 4µg/kg BW/day, reduced bone length and size in male rat offspring. Long-term studies are needed to clarify whether the increased plasma levels of P1NP in female offspring reflect development of fibrosis.

Associations between internal exposure levels of persistent organic pollutants in adipose tissue and deep infiltrating endometriosis with or without concurrent ovarian endometrioma

Endometriosis is a gynaecological disease characterized by the presence of ectopic endometrial tissue. Histologically, it appears as different sub-types, being peritoneal endometriosis, ovarian endometrioma (OvE) and deep infiltrating endometriosis (DIE), which are of major relevance due to their varying clinical presentations. A number of persistent organic pollutants (POPs) have been associated with the onset of endometriosis, yet the overall set of existing studies remains fairly divergent. In this preliminary case-control study we aimed to assess the potential associations between the internal exposure to POPs and the presence of DIE with or without concurrent OvE. Adipose tissue and serum samples were collected from surgically confirmed cases (n=55) and controls (n=44) enrolled during 2013 and 2015 in Pays de la Loire, France. Targeted pollutants (76 historical or more emerging POPs including dioxins, polychlorobiphenyls (PCB), polybrominated diphenyl ethers (PBDEs), polybrominated biphenyls (PBBs), hexabromocyclododecanes (HBCDs) and organochlorine pesticides (OCPs) were quantified by chromatography coupled to mass spectrometry. Odds ratios (ORs) and 95% confidence intervals (CI) were estimated from unconditional logistic regression adjusted for known confounding variables. The results showed significant associations between DIE and adipose tissue levels of 1.2.3.7.8 - PeCDD, OCDF, PCB 105, 114, 118 and 123, PBDE 183, PBB 153, and several OCPs including trans‑nonachlor, cis‑heptachlor epoxide, dieldrin, β-hexachlorocyclohexane and hexachlorobenzene. The largest associations were observed for OCDF followed by cis‑heptachlor epoxide, exhibiting adjusted ORs (95% CI) of 5.42 (2.73-12.85) and 5.36 (2.44-14.84) per 1-SD increase, respectively. The stratified analysis comparing both disease sub-types suggested that adipose tissue exposure markers may be more associated with DIE concurrent with OvE, however these results need to be confirmed in a larger population.

Endocrine Disrupting Chemicals, Transgenerational Epigenetics and Metabolic Diseases

Exposure to environmental chemicals can produce effects on the endocrine system through epigenetic mechanisms. These can considerably decrease or increase the sensitivity of multiple hormones depending on the dose, route, or time of exposure. The exposure of endocrine disrupting chemicals (EDCs) during the in utero period could be a critical window, altering the epigenome profile. Recently, several researchers suggest a role of EDCs in the obesity epidemic. In this brief review, we focused on how four EDCs (bisphenol A, dichlorodiphenyltrichloroethane, di-(2-ethylhexyl) phthalate and tributyltin) may underlay transgenerational epigenetic effects. We also discuss the adipogenesis signaling pathway and the impact of exposure to individual or mixtures of EDCs on the developing endocrine system. Understanding the molecular determinants of epigenetic memory across generations will provide essential insight into how environmental exposure can affect the health of individuals, as well as subsequent generations.

Prenatal bisphenol A (BPA) exposure alters the transcriptome of the neonate rat amygdala in a sex-specific manner: a CLARITY-BPA consortium study

Bisphenol A (BPA) is a widely recognized endocrine disruptor prevalent in many household items. Because experimental and epidemiological data suggest links between prenatal BPA exposure and altered affective behaviors in children, even at levels below the current US FDA No Observed Adverse Effect Level (NOAEL) of 5mg/kg body weight (bw)/day, there is concern that early life exposure may alter neurodevelopment. The current study was conducted as part of the CLARITY-BPA (Consortium Linking Academic and Regulatory Insights on BPA Toxicity) program and examined the full amygdalar transcriptome on postnatal day (PND) 1, with the hypothesis that prenatal BPA exposure would alter the expression of genes and pathways fundamental to sex-specific affective behaviors. NCTR Sprague-Dawley dams were gavaged from gestational day 6 until parturition with BPA (2.5, 25, 250, 2500, or 25000μg/kg bw/day), a reference estrogen (0.05 or 0.5μg ethinyl estradiol (EE₂)/kg bw/day), or vehicle. PND 1 amygdalae were microdissected and gene expression was assessed with qRT-PCR (all exposure groups) and RNAseq (vehicle, 25 and 250μg BPA, and 0.5μg EE₂ groups only). Our results demonstrate that that prenatal BPA exposure can disrupt the transcriptome of the neonate amygdala, at doses below the FDA NOAEL, in a sex-specific manner and indicate that the female amygdala may be more sensitive to BPA exposure during fetal development. We also provide additional evidence that developmental BPA exposure can interfere with estrogen, oxytocin, and vasopressin signaling pathways in the developing brain and alter signaling pathways critical for synaptic organization and transmission.

Polluted Pathways: Mechanisms of Metabolic Disruption by Endocrine Disrupting Chemicals

PURPOSE OF REVIEW

Environmental toxicants are increasingly implicated in the global decline in metabolic health. Focusing on diabetes, herein, the molecular and cellular mechanisms by which metabolism disrupting chemicals (MDCs) impair energy homeostasis are discussed.

RECENT FINDINGS

Emerging data implicate MDC perturbations in a variety of pathways as contributors to metabolic disease pathogenesis, with effects in diverse tissues regulating fuel utilization. Potentiation of traditional metabolic risk factors, such as caloric excess, and emerging threats to metabolism, such as disruptions in circadian rhythms, are important areas of current and future MDC research. Increasing evidence also implicates deleterious effects of MDCs on metabolic programming that occur during vulnerable developmental windows, such as in utero and early post-natal life as well as pregnancy. Recent insights into the mechanisms by which MDCs alter energy homeostasis will advance the field's ability to predict interactions with classical metabolic disease risk factors and empower studies utilizing targeted therapeutics to treat MDC-mediated diabetes.

Potentiation of ecological factors on the disruption of thyroid hormones by organo-halogenated contaminants in female polar bears (Ursus maritimus) from the Barents Sea

As apex predators, polar bears (Ursus maritimus) are among the most heavily polluted organisms in the Arctic. In addition to this anthropogenic stressor, climate warming has been shown to negatively affect their body condition, reproductive output and survival. Among potential underlying physiological mechanisms, thyroid hormones (THs), which control thermoregulation, metabolism and reproduction, can be affected by a variety of both natural and anthropogenic factors. While THs have been extensively used as proxies for pollution exposure in mammals, including polar bears, there is a lack of knowledge of their natural variations. In this context, we examined seasonal variations in body condition and circulating TH concentrations in free-ranging female polar bears. Females with variable reproductive status (i.e., solitary, with cubs of the year or with yearlings) were sampled from locations with contrasted sea ice conditions. Furthermore, we studied THs in relation to levels of organo-halogenated contaminants. As predicted, solitary females were in better condition than females caring for offspring, especially in spring. In addition, TH levels were lower in autumn compared to spring, although this seasonal effect was mainly observed in solitary females. Finally, the negative relationships between organochlorine and perfluoroalkyl substances and some THs suggest a possible alteration of homeostasis of THs. Since the latter relationships were only observed during spring, we emphasize the importance of considering the ecological factors when using THs as proxies for pollution exposure. Yet, the combined effects of natural and anthropogenic stressors on THs might impair the ability of polar bears to adapt to ongoing climate changes.

Neonatal exposure to a glyphosate-based herbicide alters uterine decidualization in rats

We investigated whether defective modulation of uterine signaling may cause decidualization failure in rats neonatally exposed to a glyphosate-based herbicide (GBH). Female pups received vehicle or 2mg/kg of GBH from postnatal day (PND) 1 to PND7. On PND8 and PND21, Wnt5a and β-catenin expression was evaluated in uterine samples. On gestational day (GD) 9, Wnt5a, Wnt7a and β-catenin expression and Dkk1 and sFRP4 mRNA were evaluated on implantation sites. On PND8, GBH-exposed rats showed increased Wnt5a and β-catenin expression in luminal epithelium (LE), whereas on PND21, they showed increased Wnt5a and β-catenin expression in subepithelial stroma but decreased β-catenin expression in glandular epithelium. On GD9, GBH-exposed rats showed decreased Wnt5a and Wnt7a expression in the antimesometrial zone and LE respectively, without changes in β-catenin expression, while Dkk1 and sFRP4 were up- and down-regulated respectively. We concluded that neonatal GBH exposure may lead to embryo losses by disturbing uterine signaling.

Retinoid X Receptor Activation Alters the Chromatin Landscape To Commit Mesenchymal Stem Cells to the Adipose Lineage

Developmental exposure to environmental factors has been linked to obesity risk later in life. Nuclear receptors are molecular sensors that play critical roles during development and, as such, are prime candidates to explain the developmental programming of disease risk by environmental chemicals. We have previously characterized the obesogen tributyltin (TBT), which activates the nuclear receptors peroxisome proliferator-activated receptor γ (PPARγ) and retinoid X receptor (RXR) to increase adiposity in mice exposed in utero. Mesenchymal stem cells (MSCs) from these mice are biased toward the adipose lineage at the expense of the osteoblast lineage, and MSCs exposed to TBT in vitro are shunted toward the adipose fate in a PPARγ-dependent fashion. To address where in the adipogenic cascade TBT acts, we developed an in vitro commitment assay that permitted us to distinguish early commitment to the adipose lineage from subsequent differentiation. TBT and RXR activators (rexinoids) had potent effects in committing MSCs to the adipose lineage, whereas the strong PPARγ activator rosiglitazone was inactive. We show that activation of RXR is sufficient for adipogenic commitment and that rexinoids act through RXR to alter the transcriptome in a manner favoring adipogenic commitment. RXR activation alters expression of enhancer of zeste homolog 2 (EZH2) and modifies genome-wide histone 3 lysine 27 trimethylation (H3K27me3) in promoting adipose commitment and programming subsequent differentiation. These data offer insights into the roles of RXR and EZH2 in MSC lineage specification and shed light on how endocrine-disrupting chemicals such as TBT can reprogram stem cell fate.

The environmental injustice of beauty: framing chemical exposures from beauty products as a health disparities concern

The obstetrics-gynecology community has issued a call to action to prevent toxic environmental chemical exposures and their threats to healthy human reproduction. Recent committee opinions recognize that vulnerable and underserved women may be impacted disproportionately by environmental chemical exposures and recommend that reproductive health professionals champion policies that secure environmental justice. Beauty product use is an understudied source of environmental chemical exposures. Beauty products can include reproductive and developmental toxicants such as phthalates and heavy metals; however, disclosure requirements are limited and inconsistent. Compared with white women, women of color have higher levels of beauty product-related environmental chemicals in their bodies, independent of socioeconomic status. Even small exposures to toxic chemicals during critical periods of development (such as pregnancy) can trigger adverse health consequences (such as impacts on fertility and pregnancy, neurodevelopment, and cancer). In this commentary, we seek to highlight the connections between environmental justice and beauty product-related chemical exposures. We describe racial/ethnic differences in beauty product use (such as skin lighteners, hair straighteners, and feminine hygiene products) and the potential chemical exposures and health risks that are associated with these products. We also discuss how targeted advertising can take advantage of mainstream beauty norms to influence the use of these products. Reproductive health professionals can use this information to advance environmental justice by being prepared to counsel patients who have questions about toxic environmental exposures from beauty care products and other sources. Researchers and healthcare providers can also promote health-protective policies such as improved ingredient testing and disclosure for the beauty product industry. Future clinical and public health research should consider beauty product use as a factor that may shape health inequities in women's reproductive health across the life course.

The effects of in utero bisphenol A exposure on ovarian follicle numbers and steroidogenesis in the F1 and F2 generations of mice

Bisphenol A (BPA) is a commonly used plasticizer. Previous studies show that in utero exposure to BPA affects reproductive outcomes in the F1-F3 generations of mice. However, its multigenerational effects on ovarian histology and steroidogenesis over the reproductive lifespan are unknown. Thus, we tested the hypothesis that BPA has multigenerational effects on follicle numbers and steroidogenesis. Mice were exposed in utero to vehicle control or BPA (0.5, 20, and 50μg/kg/day). Ovaries were collected for histological and gene expression analyses and sera were collected for hormone assays. In utero BPA exposure decreased preantral follicle numbers, cytochrome P450 aromatase mRNA levels, and estradiol levels in the F1 generation, whereas it decreased testosterone levels and altered steroidogenic acute regulatory protein, cytochrome P450 cholesterol side-chain cleavage, 3β-hydroxysteroid dehydrogenase 1, and cytochrome P450 aromatase mRNA levels in the F2 generation. These data suggest that BPA has multigenerational effects on the ovary in mice.

Association between Exposure to p,p'-DDT and Its Metabolite p,p'-DDE with Obesity: Integrated Systematic Review and Meta-Analysis

BACKGROUND

The prevalence of obesity is increasing in all countries, becoming a substantial public health concern worldwide. Increasing evidence has associated obesity with persistent pollutants such as the pesticide DDT and its metabolite p,p'-DDE.

OBJECTIVES

Our objective was to systematically review the literature on the association between exposure to the pesticide DDT and its metabolites and obesity to develop hazard identification conclusions.

METHODS

We applied a systematic review-based strategy to identify and integrate evidence from epidemiological, in vivo, and in vitro studies. The evidence from prospective epidemiological studies was quantitatively synthesized by meta-analysis. We rated the body of evidence and integrated the streams of evidence to systematically develop hazard identification conclusions.

RESULTS

We identified seven epidemiological studies reporting prospective associations between exposure to p,p'-DDE and adiposity assessed by body mass index (BMI) z-score. The results from the meta-analysis revealed positive associations between exposure to p,p'-DDE and BMI z-score (β=0.13 BMI z-score (95% CI: 0.01, 0.25) per log increase of p,p'-DDE). Two studies constituted the primary in vivo evidence. Both studies reported positive associations between exposure to p,p'-DDT and increased adiposity in rodents. We identified 19 in vivo studies and 7 in vitro studies that supported the biological plausibility of the obesogenic effects of p,p'-DDT and p,p'-DDE.

CONCLUSIONS

We classified p,p'-DDT and p,p'-DDE as "presumed" to be obesogenic for humans, based on a moderate level of primary human evidence, a moderate level of primary in vivo evidence, and a moderate level of supporting evidence from in vivo and in vitro studies. https://doi.org/10.1289/EHP527.

Molecular mechanisms involved in the non-monotonic effect of bisphenol-a on ca2+ entry in mouse pancreatic β-cells

In regulatory toxicology, the dose-response relationship is a key element towards fulfilling safety assessments and satisfying regulatory authorities. Conventionally, the larger the dose, the greater the response, following the dogma “the dose makes the poison”. Many endocrine disrupting chemicals, including bisphenol-A (BPA), induce non-monotonic dose response (NMDR) relationships, which are unconventional and have tremendous implications in risk assessment. Although several molecular mechanisms have been proposed to explain NMDR relationships, they are largely undemonstrated. Using mouse pancreatic β-cells from wild-type and oestrogen receptor ERβ−/− mice, we found that exposure to increasing doses of BPA affected Ca²⁺ entry in an NMDR manner. Low doses decreased plasma membrane Ca²⁺ currents after downregulation of Cav2.3 ion channel expression, in a process involving ERβ. High doses decreased Ca²⁺ currents through an ERβ-mediated mechanism and simultaneously increased Ca²⁺ currents via oestrogen receptor ERα. The outcome of both molecular mechanisms explains the NMDR relationship between BPA and Ca²⁺ entry in β-cells.

Understanding Epigenetic Effects of Endocrine Disrupting Chemicals: From Mechanisms to Novel Test Methods

Endocrine-disrupting chemicals (EDCs) are man-made chemicals that interfere with hormonal signalling pathways. They are used in, for example, production of common household materials, in resin-based medical supplies and in pesticides. Thus, they are environmentally ubiquitous and human beings and wildlife are exposed to them on a daily basis. Early-life exposure to EDCs has been associated with later-life adversities such as obesity, diabetes and cancer. Mechanisms underlying such associations are unknown but are likely to be mediated by epigenetic changes induced by EDCs. Epigenetics is the study of changes in gene function that are heritable but do not entail a change in DNA sequence. EDCs have been shown to affect epigenetic marks such as DNA methylation and histone modifications. The scope of this article was to review today's knowledge about mechanisms involved in EDC-induced epigenetic changes and to discuss how this knowledge could be used for designing novel methods addressing epigenetic effects of EDCs.