Arsenic exposure induces glucose intolerance and alters global energy metabolism

Analysis of arsenic-modulated expression of hypothalamic estrogen receptor, thyroid receptor, and peroxisome proliferator-activated receptor gamma mRNA and simultaneous mitochondrial morphology and respiration rates in the mouse

Arsenic has been identified as an environmental toxicant acting through various mechanisms, including the disruption of endocrine pathways. The present study assessed the ability of a single intraperitoneal injection of arsenic, to modify the mRNA expression levels of estrogen- and thyroid hormone receptors (ERα,β; TRα,β) and peroxisome proliferator-activated receptor gamma (PPARγ) in hypothalamic tissue homogenates of prepubertal mice in vivo. Mitochondrial respiration (MRR) was also measured, and the corresponding mitochondrial ultrastructure was analyzed. Results show that ERα,β, and TRα expression was significantly increased by arsenic, in all concentrations examined. In contrast, TRβ and PPARγ remained unaffected after arsenic injection. Arsenic-induced dose-dependent changes in state 4 mitochondrial respiration (St4). Mitochondrial morphology was affected by arsenic in that the 5 mg dose increased the size but decreased the number of mitochondria in agouti-related protein- (AgRP), while increasing the size without affecting the number of mitochondria in pro-opiomelanocortin (POMC) neurons. Arsenic also increased the size of the mitochondrial matrix per host mitochondrion. Complex analysis of dose-dependent response patterns between receptor mRNA, mitochondrial morphology, and mitochondrial respiration in the neuroendocrine hypothalamus suggests that instant arsenic effects on receptor mRNAs may not be directly reflected in St3-4 values, however, mitochondrial dynamics is affected, which predicts more pronounced effects in hypothalamus-regulated homeostatic processes after long-term arsenic exposure.

Adverse Health Effects of the Long-Term Simultaneous Exposure to Arsenic and Particulate Matter in a Murine Model

PM2.5 and arsenic are two of the most hazardous substances for humans that coexist worldwide. Independently, they might cause multiple organ damage. However, the combined effect of PM2.5 and arsenic has not been studied. Here, we used an animal model of simultaneous exposure to arsenic and PM2.5. Adult Wistar rats were exposed to PM2.5, As, or PM2.5 + As and their corresponding control groups. After 7, 14, and 28 days of exposure, the animals were euthanized and serum, lungs, kidneys, and hearts were collected. Analysis performed showed high levels of lung inflammation in all experimental groups, with an additive effect in the coexposed group. Besides, we observed cartilaginous metaplasia in the hearts of all exposed animals. The levels of creatine kinase, CK-MB, and lactate dehydrogenase increased in experimental groups. Tissue alterations might be related to oxidative stress through increased GPx and NADPH oxidase activity. The findings of this study suggest that exposure to arsenic, PM2.5, or coexposure induces high levels of oxidative stress, which might be associated with lung inflammation and heart damage. These findings highlight the importance of reducing exposure to these pollutants to protect human health.

Effect of arsenic on the risk of gestational diabetes mellitus: a systematic review and meta-analysis

BACKGROUND

Gestational diabetes mellitus (GDM) is a complication of pregnancy associated with numerous adverse outcomes. There may be a potential link between GDM and arsenic (As) exposure, but this hypothesis remains controversial. This meta-analysis summarizes the latest studies evaluating the association between As and GDM.

METHODS

A comprehensive search of the PubMed, Embase, and Scopus databases up to September 2023 was performed. The pooled estimates with 95% CIs were presented using forest plots. Estimates were calculated with random effects models, and subgroup and sensitivity analyses were conducted to address heterogeneity.

RESULTS

A total of 13 eligible studies involving 2575 patients with GDM were included in this meta-analysis. The results showed that women exposed to As had a significantly increased risk of GDM (OR 1.47, 95% CI: 1.11 to 1.95, P = 0.007). Subgroup analyses suggested that the heterogeneity might be attributed to the years of publication. In addition, sensitivity analysis confirmed the robust and reliable results.

CONCLUSIONS

This analysis suggested that women exposed to As have a greater risk of GDM. However, the significant heterogeneity across studies requires careful interpretation.

REGISTRATION

The PROSPERO registration ID is CRD42023461820.

Glycemic Changes Related to Arsenic Exposure: An Overview of Animal and Human Studies

BACKGROUND

Arsenic (As) is a risk factor associated with glycemic alterations. However, the mechanisms of action and metabolic aspects associated with changes in glycemic profiles have not yet been completely elucidated. Therefore, in this review, we aimed to investigate the metabolic aspects of As and its mechanism of action associated with glycemic changes.

METHODS

We searched the PubMed (MEDLINE) and Google Scholar databases for relevant articles published in English. A combination of free text and medical subject heading keywords and search terms was used to construct search equations. The search yielded 466 articles; however, only 50 were included in the review.

RESULTS

We observed that the relationship between As exposure and glycemic alterations in humans may be associated with sex, smoking status, body mass index, age, occupation, and genetic factors. The main mechanisms of action associated with changes induced by exposure to As in the glycemic profile identified in animals are increased oxidative stress, reduced expression of glucose transporter type 4, induction of inflammatory factor expression and dysfunction of pancreatic β cells.

CONCLUSIONS

Therefore, As exposure may be associated with glycemic alterations according to inter-individual differences.

Arsenic induces metabolome remodeling in mature human adipocytes

Human lifetime exposure to arsenic through drinking water, food supply or industrial pollution leads to its accumulation in many organs such as liver, kidneys, lungs or pancreas but also adipose tissue. Recently, population-based studies revealed the association between arsenic exposure and the development of metabolic diseases such as obesity and type 2 diabetes. To shed light on the molecular bases of such association, we determined the concentration that inhibited 17% of cell viability and investigated the effects of arsenic acute exposure on adipose-derived human mesenchymal stem cells differentiated in vitro into mature adipocytes and treated with sodium arsenite (NaAsO2, 10 nM to 10 µM). Untargeted metabolomics and gene expression analyses revealed a strong dose-dependent inhibition of lipogenesis and lipolysis induction, reducing the cellular ability to store lipids. These dysregulations were emphasized by the inhibition of the cellular response to insulin, as shown by the perturbation of several genes and metabolites involved in the mentioned biological pathways. Our study highlighted the activation of an adaptive oxidative stress response with the strong induction of metallothioneins and increased glutathione levels in response to arsenic accumulation that could exacerbate the decreased insulin sensitivity of the adipocytes. Arsenic exposure strongly affected the expression of arsenic transporters, responsible for arsenic influx and efflux, and induced a pro-inflammatory state in adipocytes by enhancing the expression of the inflammatory interleukin 6 (IL6). Collectively, our data showed that an acute exposure to low levels of arsenic concentrations alters key adipocyte functions, highlighting its contribution to the development of insulin resistance and the pathogenesis of metabolic disorders.

Associations between area-level arsenic exposure and adverse birth outcomes: An Echo-wide cohort analysis

BACKGROUND

Drinking water is a common source of exposure to inorganic arsenic. In the US, the Safe Drinking Water Act (SDWA) was enacted to protect consumers from exposure to contaminants, including arsenic, in public water systems (PWS). The reproductive effects of preconception and prenatal arsenic exposure in regions with low to moderate arsenic concentrations are not well understood.

OBJECTIVES

This study examined associations between preconception and prenatal exposure to arsenic violations in water, measured via residence in a county with an arsenic violation in a regulated PWS during pregnancy, and five birth outcomes: birth weight, gestational age at birth, preterm birth, small for gestational age (SGA), and large for gestational age (LGA).

METHODS

Data for arsenic violations in PWS, defined as concentrations exceeding 10 parts per billion, were obtained from the Safe Drinking Water Information System. Participants of the Environmental influences on Child Health Outcomes Cohort Study were matched to arsenic violations by time and location based on residential history data. Multivariable, mixed effects regression models were used to assess the relationship between preconception and prenatal exposure to arsenic violations in drinking water and birth outcomes.

RESULTS

Compared to unexposed infants, continuous exposure to arsenic from three months prior to conception through birth was associated with 88.8 g higher mean birth weight (95% CI: 8.2, 169.5), after adjusting for individual-level confounders. No statistically significant associations were observed between any preconception or prenatal violations exposure and gestational age at birth, preterm birth, SGA, or LGA.

CONCLUSIONS

Our study did not identify associations between preconception and prenatal arsenic exposure, defined by drinking water exceedances, and adverse birth outcomes. Exposure to arsenic violations in drinking water was associated with higher birth weight. Future studies would benefit from more precise geodata of water system service areas, direct household drinking water measurements, and exposure biomarkers.

The Role of the Nuclear Receptor FXR in Arsenic-Induced Glucose Intolerance in Mice

Inorganic arsenic in drinking water is prioritized as a top environmental contaminant by the World Health Organization, with over 230 million people potentially being exposed. Arsenic toxicity has been well documented and is associated with a plethora of human diseases, including diabetes, as established in numerous animal and epidemiological studies. Our previous study revealed that arsenic exposure leads to the inhibition of nuclear receptors, including LXR/RXR. To this end, FXR is a nuclear receptor central to glucose and lipid metabolism. However, limited studies are available for understanding arsenic exposure-FXR interactions. Herein, we report that FXR knockout mice developed more profound glucose intolerance than wild-type mice upon arsenic exposure, supporting the regulatory role of FXR in arsenic-induced glucose intolerance. We further exposed mice to arsenic and tested if GW4064, a FXR agonist, could improve glucose intolerance and dysregulation of hepatic proteins and serum metabolites. Our data showed arsenic-induced glucose intolerance was remarkably diminished by GW4064, accompanied by a significant ratio of alleviation of dysregulation in hepatic proteins (83%) and annotated serum metabolites (58%). In particular, hepatic proteins "rescued" from arsenic toxicity by GW4064 featured members of glucose and lipid utilization. For instance, the expression of PCK1, a candidate gene for diabetes and obesity that facilitates gluconeogenesis, was repressed under arsenic exposure in the liver, but revived with the GW4064 supplement. Together, our comprehensive dataset indicates FXR plays a key role and may serve as a potential therapeutic for arsenic-induced metabolic disorders.

Association between Heavy Metals, Metalloids and Metabolic Syndrome: New Insights and Approaches

Metabolic syndrome (MetS) is an important public health issue that affects millions of people around the world and is growing to pandemic-like proportions. This syndrome is defined by the World Health Organization (WHO) as a pathologic condition characterized by abdominal obesity, insulin resistance, hypertension, and hyperlipidemia. Moreover, the etiology of MetS is multifactorial, involving many environmental factors, including toxicant exposures. Several studies have associated MetS with heavy metals exposure, which is the focus of this review. Environmental and/or occupational exposure to heavy metals are a major risk, contributing to the development of chronic diseases. Of particular note, toxic metals such as mercury, lead, and cadmium may contribute to the development of MetS by altering oxidative stress, IL-6 signaling, apoptosis, altered lipoprotein metabolism, fluid shear stress and atherosclerosis, and other mechanisms. In this review, we discuss the known and potential roles of heavy metals in MetS etiology as well as potential targeted pathways that are associated with MetS. Furthermore, we describe how new approaches involving proteomic and transcriptome analysis, as well as bioinformatic tools, may help bring about an understanding of the involvement of heavy metals and metalloids in MetS.

Arsenic in brown rice: do the benefits outweigh the risks?

Brown rice has been advocated for as a healthier alternative to white rice. However, the concentration of arsenic and other pesticide contaminants is greater in brown rice than in white. The potential health risks and benefits of consuming more brown rice than white rice remain unclear; thus, mainstream nutritional messaging should not advocate for brown rice over white rice. This mini-review aims to summarize the most salient concepts related to dietary arsenic exposure with emphasis on more recent findings and provide consumers with evidence of both risks and benefits of consuming more brown rice than white rice. Despite risk-benefit assessments being a challenging new frontier in nutrition, researchers should pursue an assessment to validate findings and solidify evidence. In the interim, consumers should be cognizant that the dose of arsenic exposure determines its toxicity, and brown rice contains a greater concentration of arsenic than white rice.

Arsenic metabolism, diabetes prevalence, and insulin resistance among Mexican Americans: A mendelian randomization approach

Background

Differences in arsenic metabolism capacity may influence risk for type 2 diabetes, but the mechanistic drivers are unclear. We evaluated the associations between arsenic metabolism with overall diabetes prevalence and with static and dynamic measures of insulin resistance among Mexican Americans living in Starr County, Texas.

Methods

We utilized data from cross-sectional studies conducted in Starr County, Texas, from 2010-2014. A Mendelian randomization approach was utilized to evaluate the associations between arsenic metabolism and type 2 diabetes prevalence using the intronic variant in the arsenic methylating gene, rs9527, as the instrumental variable for arsenic metabolism. To further assess mechanisms for diabetes pathogenesis, proportions of the urinary arsenic metabolites were employed to assess the association between arsenic metabolism and insulin resistance among participants without diabetes. Urinary biomarkers of arsenic metabolites were modeled as individual proportions of the total. Arsenic metabolism was evaluated both with a static outcome of insulin resistance, homeostatic measure of assessment (HOMA-IR), and a dynamic measure of insulin sensitivity, Matsuda Index.

Results

Among 475 Mexican American participants from Starr County, higher metabolism capacity for arsenic is associated with higher diabetes prevalence driven by worse insulin resistance. Presence of the minor T allele of rs9527 is independently associated with an increase in the proportion of monomethylated arsenic (MMA%) and is associated with an odds ratio of 0.50 (95% CI: 0.24, 0.90) for type 2 diabetes. This association was conserved after potential covariate adjustment. Furthermore, among participants without type 2 diabetes, the highest quartile of MMA% was associated with 22% (95% CI: -33.5%, -9.07%) lower HOMA-IR and 56% (95% CI: 28.3%, 91.3%) higher Matsuda Index for insulin sensitivity.

Conclusions

Arsenic metabolism capacity, indicated by a lower proportion of monomethylated arsenic, is associated with increased diabetes prevalence driven by an insulin resistant phenotype among Mexican Americans living in Starr County, Texas.

Diosmin exerts hepatoprotective and antihyperglycemic effects against sodium arsenite-induced toxicity through the modulation of oxidative stress and inflammation in mice

BACKGROUND

Chronic exposure to high concentrations of inorganic arsenic (NaAsO₂) in drinking water is related to an increase in the risk of liver toxicity and diabetes. Diosmin has various pharmacological properties, including antioxidant and anti-inflammatory properties. This study was designed to investigate the protective effects of diosmin on diabetes and hepatotoxicity caused by NaAsO₂.

METHODS

Sixty male 8-week-old NMRI mice, weighing 25 ± 2 g, were randomly selected and put into six groups. The control (Group 1) was treated orally with distilled water, group 2 was treated with diosmin (100 mg/kg, p.o), group 3 received NaAsO₂ (10 mg/kg, p.o), and groups 4, 5, 6 received diosmin (25, 50, 100 mg/kg, p.o), respectively and NaAsO₂ (10 mg/kg, p.o). After 29 days, fasting blood sugar (FBS) measurement and glucose tolerance test were done. The mice were sacrificed on day 31, and blood and tissue (liver and pancreas) samples were taken. Then, serum and tissue samples were studied for biochemical and histological evaluations.

RESULTS

The results demonstrated that diosmin ameliorated glucose intolerance and decreased FBS compared to the NaAsO₂ group. Diosmin (50 and 100 mg/kg) improved the serum factors of liver function (alanine aminotransferase, aspartate transaminase, and alkaline phosphatase) in the groups receiving NaAsO₂. Moreover, increased levels of nitric oxide, tumor necrosis factor-alpha, and thiobarbituric acid reactive substances in liver tissue induced by NaAsO₂ were diminished by diosmin treatment. Administration of diosmin increased total thiol and enzymatic activities of catalase, superoxide dismutase, and glutathione peroxidase in liver tissue. Furthermore, treatment with diosmin reduced the increase in protein amount of Sirtuin 3 and nuclear factor kappa B in the groups receiving NaAsO₂. Also, the liver and pancreas histological lesions induced by NaAsO₂ were attenuated by diosmin treatment.

CONCLUSION

Diosmin has a preventive effect against hepatotoxicity and diabetes induced by NaAsO₂ in mice through its antioxidant and anti-inflammatory properties.

Arsenic induces the global hypophosphorylation of insulin receptor substrate proteins in differentiated human neuroblastoma SH-SY5Y cells

We recently reported that arsenic disrupted neuronal insulin signaling. Here, we further investigated the effect of arsenic on insulin receptor substrate (IRS) proteins, which are crucial downstream signaling molecules of insulin in differentiated human neuroblastoma SH-SY5Y cells. We also found that prolonged arsenic treatment accelerated the migration of IRS1 and IRS2 on SDS-PAGE. Treatment with phosphatases abolished the arsenic-induced increased mobility of IRS, suggesting that the electrophoretic mobility shift of IRS on SDS-PAGE by arsenic was phosphorylation-dependent. By using label-free mass spectrometry, the phosphorylation sites of IRS1 were found to be S24, S345, S636, T774, S1057, S1058, and S1070, while those of IRS2 were at S645, Y653, T657, S665, S667, S669, S672, S915, and S1203, which were at least 2-fold lower than found in the control. These findings indicated a global hypophosphorylation of IRS proteins after prolonged arsenic treatment. In addition, four novel phosphorylation sites were identified on IRS1 (T774, S1057, S1058, and S1070), with another two on IRS2 (S665 and S667). As basal IRS phosphorylation plays an important role in insulin signaling, the reduction of IRS phosphorylation on multiple residues may underlie arsenic-impaired insulin signaling in neurons.

Critical Overview on Endocrine Disruptors in Diabetes Mellitus

Diabetes mellitus is a major public health problem in all countries due to its high human and economic burden. Major metabolic alterations are associated with the chronic hyperglycemia that characterizes diabetes and causes devastating complications, including retinopathy, kidney failure, coronary disease and increased cardiovascular mortality. The most common form is type 2 diabetes (T2D) accounting for 90 to 95% of the cases. These chronic metabolic disorders are heterogeneous to which genetic factors contribute, but so do prenatal and postnatal life environmental factors including a sedentary lifestyle, overweight, and obesity. However, these classical risk factors alone cannot explain the rapid evolution of the prevalence of T2D and the high prevalence of type 1 diabetes in particular areas. Among environmental factors, we are in fact exposed to a growing amount of chemical molecules produced by our industries or by our way of life. In this narrative review, we aim to give a critical overview of the role of these pollutants that can interfere with our endocrine system, the so-called endocrine-disrupting chemicals (EDCs), in the pathophysiology of diabetes and metabolic disorders.

Relationships Between Urinary Metals and Diabetes Traits Among Mexican Americans in Starr County, Texas, USA

Hispanics/Latinos have higher rates of type 2 diabetes (T2D), and the origins of these disparities are poorly understood. Environmental endocrine-disrupting chemicals (EDCs), including some metals and metalloids, are implicated as diabetes risk factors. Data indicate that Hispanics/Latinos may be disproportionately exposed to EDCs, yet they remain understudied with respect to environmental exposures and diabetes. The objective of this study is to determine how metal exposures contribute to T2D progression by evaluating the associations between 8 urinary metals and measures of glycemic status in 414 normoglycemic or prediabetic adults living in Starr County, Texas, a Hispanic/Latino community with high rates of diabetes and diabetes-associated mortality. We used multivariable linear regression to quantify the differences in homeostatic model assessments for pancreatic β-cell function, insulin resistance, and insulin sensitivity (HOMA-β, HOMA-IR, HOMA-S, respectively), plasma insulin, plasma glucose, and hemoglobin A1c (HbA1c) associated with increasing urinary metal concentrations. Quantile-based g-computation was utilized to assess mixture effects. After multivariable adjustment, urinary arsenic and molybdenum were associated with lower HOMA-β, HOMA-IR, and plasma insulin levels and higher HOMA-S. Additionally, higher urinary copper levels were associated with a reduced HOMA-β. Lastly, a higher concentration of the 8 metal mixtures was associated with lower HOMA-β, HOMA-IR, and plasma insulin levels as well as higher HOMA-S. Our data indicate that arsenic, molybdenum, copper, and this metal mixture are associated with alterations in measures of glucose homeostasis among non-diabetics in Starr County. This study is one of the first to comprehensively evaluate associations of urinary metals with glycemic measures in a high-risk Mexican American population.

Interactions between arsenic exposure, high-fat diet and NRF2 shape the complex responses in the murine gut microbiome and hepatic metabolism

Inorganic arsenic (iAs) exposure has been associated to various detrimental effects such as development of metabolic syndrome and type 2 diabetes via oxidative stress and induced prolonged activation of the NRF2 transcription factor. Such effects can be aggravated by poor dietary habits. The role of gut microbiota in promoting metabolic changes in response to arsenic has yet to be precisely defined. To address the complexity of the interactions between diet, NFE2L2/NRF2, and gut microbiota, we studied the chronic effects of iAs exposure in wild-type (WT) and Nrf2-/- mice fed normal (ND) vs. high-fat diet (HFD), on the gut microbial community in the context of hepatic metabolism. We demonstrate that all treatments and interactions influenced bacteria and metabolic profiles, with dietary differences causing a strong overlap of responses between the datasets. By identifying five metabolites of known microbial origin and following their fate across treatments, we provide examples on how gut microbial products can participate in the development of iAs and HFD-induced metabolic disease. Overall, our results underline the importance of the microbial community in driving gut-liver-cross talk during iAs and HFD exposure.

Effects of carnosic acid on arsenic-induced liver injury in mice: A comparative transcriptomics analysis

BACKGROUND

Long-term chronic exposure to arsenic can cause different degrees of liver injury. Till date, its molecular mechanism has not meant fully elucidated. Evidence indicates that Carnosic acid (CA) has a protective role in arsenic-induced liver injury. This study aimed to reveal the potential targets and evaluate the potential effect of CA intervention at transcriptional level, and provide reference for the intervention of arsenic-induced liver injury.

METHODS

Arsenic-induced liver injury and CA intervention models were established in C57BL/6 mice. RNA sequencing technique was carried out to obtain the differentially expressed gene (DEG) profiles. The common covariant DEGs between arsenic induction and CA intervention was screened by comparative transcriptomic analysis methods. QRT-PCR was used to verify the covariant DEGs.

RESULTS

Transcriptome results showed that 220 DEGs were identified after arsenic induction. 267 DEGs were identified after CA intervention (|fold change| > 2.0 and adjusted P < 0.05). 42 covariant DEGs were discovered between the comparison of "AS vs Control" and "AS & CA vs AS". In addition, hub gene analysis revealed a total of 8 covariant DEGs (Ehhadh, Fgf21, Cyp2b10, Plin2, Aacs, Cyp7a1, Per2 and Mylip). The mRNA expressions of Fgf21 and Plin2 were significantly increased (P < 0.05) and the mRNA expressions of Cyp2b10, Cyp7a1, Per2 and Mylip were significantly decreased (P < 0.05) after arsenic induction. On the contrary, the changes of these DEGs were reversed after CA intervention.

CONCLUSION

The present study would be helpful to understand the potential health effects of arsenic-induced liver injury and identify new potential targets, and provide a reference for the intervention of CA.

In situ analysis of variations of arsenicals, microbiome and transcriptome profiles along murine intestinal tract

In situ-based studies on microbiome-host interactions after arsenic exposure are few. In this study, the variations in arsenics, microbiota, and host genes along murine intestinal tracts were determined after arsenic exposure for two months. There was a gradual increase in the concentration of total As (C_tAs) in feces from ileum to colon, whereas C_tAs in the corresponding tissues were relatively stable. Differences in arsenic levels between feces and tissues were significantly different. The proportion of arsenite (iAs^Ⅲ) in feces gradually decreased, however, it gradually increased in tissues. After arsenic exposure, the diversity and abundance of microbial community and networks in each segment were significantly dysregulated. Notably, 328, 579 and 90 differently expressed genes were detected in ileum, cecum, and colon, respectively. In addition, microbiome and transcriptome analyses showed a significant correlation between the abundance of Faecalibaculum and expressions of Plb1, Hspa1b, Areg and Duoxa2 genes. This implies that they may be involved in arsenic biotransformation. In vitro experiments using Biofidobactrium and Lactobacillus showed that probiotics have arsenic transformation abilities. Therefore, gut microbiome may modulate arsenic accumulation, excretion and detoxification along the digestive tract. Moreover, the abundance and diversity of gut microbiome may be related to the changes in host health.

Is Arsenic Exposure a Risk Factor for Metabolic Syndrome? A Review of the Potential Mechanisms

Exposure to arsenic in drinking water is a worldwide health problem. This pollutant is associated with increased risk of developing chronic diseases, including metabolic diseases. Metabolic syndrome (MS) is a complex pathology that results from the interaction between environmental and genetic factors. This condition increases the risk of developing type 2 diabetes, cardiovascular diseases, and cancer. The MS includes at least three of the following signs, central obesity, impaired fasting glucose, insulin resistance, dyslipidemias, and hypertension. Here, we summarize the existing evidence of the multiple mechanisms triggered by arsenic to developing the cardinal signs of MS, showing that this pollutant could contribute to the multifactorial origin of this pathology.

Environmental arsenic exposure and its contribution to human diseases, toxicity mechanism and management

Arsenic is a well-recognized environmental contaminant that occurs naturally through geogenic processes in the aquifer. More than 200 million people around the world are potentially exposed to the elevated level of arsenic mostly from Asia and Latin America. Many adverse health effects including skin diseases (i.e., arsenicosis, hyperkeratosis, pigmentation changes), carcinogenesis, and neurological diseases have been reported due to arsenic exposure. In addition, arsenic has recently been shown to contribute to the onset of non-communicable diseases, such as diabetes mellitus and cardiovascular diseases. The mechanisms involved in arsenic-induced diabetes are pancreatic β-cell dysfunction and death, impaired insulin secretion, insulin resistance and reduced cellular glucose transport. Whereas, the most proposed mechanisms of arsenic-induced hypertension are oxidative stress, disruption of nitric oxide signaling, altered vascular response to neurotransmitters and impaired vascular muscle calcium (Ca²⁺) signaling, damage of renal, and interference with the renin-angiotensin system (RAS). However, the contributions of arsenic exposure to non-communicable diseases are complex and multifaceted, and little information is available about the molecular mechanisms involved in arsenic-induced non-communicable diseases and also no suitable therapeutic target identified yet. Therefore, in the future, more basic research is necessary to identify the appropriate therapeutic target for the treatment and management of arsenic-induced non-communicable diseases. Several reports demonstrated that a daily balanced diet with proper nutrient supplements (vitamins, micronutrients, natural antioxidants) has shown effective to reduce the damages caused by arsenic exposure. Arsenic detoxication through natural compounds or nutraceuticals is considered a cost-effective treatment/management and researchers should focus on these alternative options. This review paper explores the scenarios of arsenic contamination in groundwater with an emphasis on public health concerns. It also demonstrated arsenic sources, biogeochemistry, toxicity mechanisms with therapeutic targets, arsenic exposure-related human diseases, and onsets of cardiovascular diseases as well as feasible management options for arsenic toxicity.

Dietary Selenium Deficiency Partially Mimics the Metabolic Effects of Arsenic

Chronic arsenic exposure via drinking water is associated with diabetes in human pop-ulations throughout the world. Arsenic is believed to exert its diabetogenic effects via multiple mechanisms, including alterations to insulin secretion and insulin sensitivity. In the past, acute arsenicosis has been thought to be partially treatable with selenium supplementation, though a potential interaction between selenium and arsenic had not been evaluated under longer-term exposure models. The purpose of the present study was to explore whether selenium status may augment arsenic's effects during chronic arsenic exposure. To test this possibility, mice were exposed to arsenic in their drinking water and provided ad libitum access to either a diet replete with selenium (Control) or deficient in selenium (SelD). Arsenic significantly improved glucose tolerance and decreased insulin secretion and β-cell function in vivo. Dietary selenium deficiency resulted in similar effects on glucose tolerance and insulin secretion, with significant interactions between arsenic and dietary conditions in select insulin-related parameters. The findings of this study highlight the complexity of arsenic's metabolic effects and suggest that selenium deficiency may interact with arsenic exposure on β-cell-related physiological parameters.

Inappropriately sweet: Environmental endocrine-disrupting chemicals and the diabetes pandemic

Afflicting hundreds of millions of individuals globally, diabetes mellitus is a chronic disorder of energy metabolism characterized by hyperglycemia and other metabolic derangements that result in significant individual morbidity and mortality as well as substantial healthcare costs. Importantly, the impact of diabetes in the United States is not uniform across the population; rather, communities of color and those with low income are disproportionately affected. While excessive caloric intake, physical inactivity, and genetic susceptibility are undoubted contributors to diabetes risk, these factors alone fail to fully explain the rapid global rise in diabetes rates. Recently, environmental contaminants acting as endocrine-disrupting chemicals (EDCs) have been implicated in the pathogenesis of diabetes. Indeed, burgeoning data from cell-based, animal, population, and even clinical studies now indicate that a variety of structurally distinct EDCs of both natural and synthetic origin have the capacity to alter insulin secretion and action as well as global glucose homeostasis. This chapter reviews the evidence linking EDCs to diabetes risk across this spectrum of evidence. It is hoped that improving our understanding of the environmental drivers of diabetes development will illuminate novel individual-level and policy interventions to mitigate the impact of this devastating condition on vulnerable communities and the population at large.

Effects of arsenic and heavy metals on metabolic pathways in cells of human origin: Similarities and differences

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There are distinctive overlaps in different heavy metal affected metabolic pathways.

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Affected pathways vary according to the tissue origin and maturity of the cell.

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Arsenic appears to have relatively more pleiotropic effects on metabolic pathways.

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Some of the arsenic affected pathways are associated with diabetes.

Various anthropogenic and natural events over the years have gradually increased human exposure to various heavy metals. Several of these heavy metals including cadmium, mercury, nickel, chromium, and the metalloid arsenic among others, have created major public health concerns for their high level of toxicities. Identification of the general as well as the differentially affected cellular metabolic pathways will help understanding the molecular mechanism of different heavy metal-induced toxicities. In this study, we analyzed 25 paired (control vs. treated) transcriptomic datasets derived following treatment of various human cells with different heavy metals and metalloid (arsenic, cadmium, chromium, iron, mercury, nickel and vanadium) to identify the affected metabolic pathways. The effects of these metals on metabolic pathways depend not only on the metals per se, but also on the nature of the treated cells. Tissue of origin, therefore, must be considered while assessing the effects of any particular heavy metal or metalloid. Among the metals and metalloid, arsenic appears to have relatively more pleiotropic influences on cellular metabolic pathways including those known to have association with diabetes. Although only two stem cell derived datasets are included in the current study, effects of heavy metals on these cells appear to be different from other mature cells of similar tissue origin. This study provides useful information about different heavy metal affected pathways, which may be useful in further exploration using wet-lab based techniques.

Urinary metal mixtures and longitudinal changes in glucose homeostasis: The Study of Women's Health Across the Nation (SWAN)

BACKGROUND

Epidemiologic studies on associations between metals and insulin resistance and β-cell dysfunction have been cross-sectional and focused on individual metals.

OBJECTIVE

We assessed the association of exposure to metal mixtures, based on assessment of 15 urinary metals, with both baseline levels and longitudinal changes in homeostatic model assessments for insulin resistance (HOMA-IR) and β-cell function (HOMA-β).

METHODS

We examined 1262 women, aged 45-56 years at baseline (1999-2000), who were followed through 2015-2016, from the Study of Women's Health Across the Nation. Urinary concentrations of 15 metals (arsenic, barium, cadmium, cobalt, cesium, copper, mercury, manganese, molybdenum, nickel, lead, antimony, tin, thallium, and zinc) were determined at baseline. HOMA-IR and HOMA-β were repeatedly measured over 16 years of follow-up. A two-stage modeling was used to account for correlations in dependent and independent variables: In stage-1, linear mixed effects models were used to estimate the participant-specific baseline HOMA levels from random intercepts and participant-specific rates of changes from random slopes. In stage-2, adaptive elastic-net (AENET) models were fit to identify components of metal mixtures associated with participant-specific baseline levels and rates of changes in HOMA-IR and HOMA-β, respectively. An environmental risk score (ERS) was used to integrate metal mixture effects from AENET results.

RESULTS

In multivariable adjusted AENET models, urinary zinc was associated with higher HOMA-IR at baseline, whereas molybdenum was associated with lower HOMA-IR at baseline. The estimated changes in baseline HOMA-IR for one standard deviation increase in log-transformed urinary metal concentrations were 5.76% (3.05%, 8.55%) for zinc and -3.25% (-5.45%, -1.00%) for molybdenum, respectively. Urinary zinc was also associated with lower HOMA- β at baseline. Arsenic was associated with a slightly faster rate of decline in HOMA-β in the AENET model evaluating associations between metals and rate of changes. Significant associations of ERS with both HOMA-IR and HOMA-β at baseline were observed. ERS for the rate of changes was not calculated and examined in relation to rates of changes in HOMA-IR and HOMA-β because only a single metal was selected by AENET.

CONCLUSION

Exposure to metal mixtures may be exerting effects on insulin resistance and β-cell dysfunction, which might be mechanisms by which metal exposures lead to elevated diabetes risks.

Arsenic Exposure Decreases Adiposity During High-Fat Feeding

OBJECTIVE

Arsenic is an endocrine-disrupting chemical associated with diabetes risk. Increased adiposity is a significant risk factor for diabetes and its comorbidities. Here, the impact of chronic arsenic exposure on adiposity and metabolic health was assessed in mice.

METHODS

Male C57BL/6J mice were provided ad libitum access to a normal or high-fat diet and water +/- 50 mg/L of sodium arsenite. Changes in body weight, body composition, insulin sensitivity, energy expenditure, and locomotor activity were measured. Measures of adiposity were compared with accumulated arsenic in the liver.

RESULTS

Despite uniform arsenic exposure, internal arsenic levels varied significantly among arsenic-exposed mice. Hepatic arsenic levels in exposed mice negatively correlated with overall weight gain, individual adipose depot masses, and hepatic triglyceride accumulation. No effects were observed in mice on a normal diet. For mice on a high-fat diet, arsenic exposure reduced fasting insulin levels, homeostatic model assessment of insulin resistance and β-cell function, and systemic insulin resistance. Arsenic exposure did not alter energy expenditure or activity.

CONCLUSIONS

Collectively, these data indicate that arsenic is antiobesogenic and that concentration at the source poorly predicts arsenic accumulation and phenotypic outcomes. In future studies, investigators should consider internal accumulation of arsenic rather than source concentration when assessing the outcomes of arsenic exposure.

Domain- and sex-specific effects of prenatal exposure to low levels of arsenic on children's development at 6 months of age: Findings from the Ma'anshan birth cohort study in China

The relationship between prenatal arsenic exposure at low levels and poor development in children, especially in regard to neurodevelopment, has aroused several concerns, but the conclusions have been inconsistent. It still remains unclear whether such adverse effect is associated with a specific profile of the developing brain in early life. To investigate the association between arsenic exposure in utero and children's development and behaviour, we performed a large prospective birth cohort study including 2315 mother-infant pairs in Anhui Province, China. The Ages and Stages Questionnaire of China (ASQ-C) was used to assess the status of children's development and behaviour at 6 months postpartum, and the levels of arsenic were determined in umbilical cord serum samples. Odds ratios for suspected developmental delay (SDD) in each domain of the ASQ-C clusters were estimated using logistic regression models. Compared with low arsenic levels group, medium and high arsenic levels were significantly associated with the increased risks of SDD in the personal-social domain among infants aged 6 months after adjustment for all potential confounders (OR = 1.33, 95% CI (1.01, 1.75) and OR = 1.47, 95% CI (1.08, 2.00), respectively). Sex stratification analysis demonstrated that this association was stronger in females. The sensitivity analyses also showed that high cord serum arsenic levels were associated with a 1.80-fold (95% CIs (1.12, 2.90)) higher risk of a more severe developmental delay in the personal-social domain among six-month-old females. Our results suggest that low-level arsenic exposure in utero could have an adverse domain-specific effect on children's development at 6 months of age, particularly among females. Further studies are warranted to support the findings and explore the mechanism of these domain-and sex-specific associations.

A State-of-the-Science Review of Arsenic's Effects on Glucose Homeostasis in Experimental Models

BACKGROUND

The prevalence of type 2 diabetes (T2D) has more than doubled since 1980. Poor nutrition, sedentary lifestyle, and obesity are among the primary risk factors. While an estimated 70% of cases are attributed to excess adiposity, there is an increased interest in understanding the contribution of environmental agents to diabetes causation and severity. Arsenic is one of these environmental chemicals, with multiple epidemiology studies supporting its association with T2D. Despite extensive research, the molecular mechanism by which arsenic exerts its diabetogenic effects remains unclear.

OBJECTIVES

We conducted a literature search focused on arsenite exposure in vivo and in vitro, using relevant end points to elucidate potential mechanisms of oral arsenic exposure and diabetes development.

METHODS

We explored experimental results for potential mechanisms and elucidated the distinct effects that occur at high vs. low exposure. We also performed network analyses relying on publicly available data, which supported our key findings.

RESULTS

While several mechanisms may be involved, our findings support that arsenite has effects on whole-body glucose homeostasis, insulin-stimulated glucose uptake, glucose-stimulated insulin secretion, hepatic glucose metabolism, and both adipose and pancreatic β -cell dysfunction.

DISCUSSION

This review applies state-of-the-science approaches to identify the current knowledge gaps in our understanding of arsenite on diabetes development. https://doi.org/10.1289/EHP4517.

Multiple metal concentrations and gestational diabetes mellitus in Taiyuan, China

BACKGROUND

The association between multiple metal concentrations and gestational diabetes mellitus (GDM) is poorly understood.

METHODS

A total of 776 women with GDM and an equal number of controls were included in the study. Concentrations of metals in participants' blood (nickel (Ni), arsenic (As), cadmium (Cd), antimony (Sb), thallium (Tl), mercury (Hg), lead (Pb)) were measured using inductively coupled plasma-mass. We used unconditional logistical regression models to estimate the associations between metals and GDM. We also employed weighted quantile sum (WQS) regression and principal components analysis (PCA) to examine metal mixtures in relation to GDM.

RESULTS

An increased risk of GDM was associated with As (OR = 1.49, 95% CI: 1.11, 2.01 for the 2nd tertile vs. the 1st tertile) and Hg (OR = 1.43, 95% CI: 1.09, 1.88 for the 3rd tertile vs. the 1st tertile). In WQS analysis, the WQS index was significantly associated with GDM (OR = 1.20, 95% CI: 1.02, 1.41). The major contributor to the metal mixture index was Hg (69.2%), followed by Pb (12.8%), and As (11.3%). Based on PCA, the second principal component, which was characterized by Hg, Ni, and Pb, was associated with an increased risk of GDM (OR = 1.46, 95% CI: 1.02, 2.08 for the highest quartile vs. the lowest quartile).

CONCLUSIONS

Our study results suggest that high metal levels are associated with an increased risk of GDM, and this increased risk is mainly driven by Hg and, to a lesser extent, by Ni, Pb, and As.

Lipid Metabolism Alterations in a Rat Model of Chronic and Intergenerational Exposure to Arsenic

Chronic exposure to arsenic (As), whether directly through the consumption of contaminated drinking water or indirectly through the daily intake of As-contaminated food, is a health threat for more than 150 million people worldwide. Epidemiological studies found an association between chronic consumption of As and several pathologies, the most common being cancer-related disorders. However, As consumption has also been associated with metabolic disorders that could lead to diverse pathologies, such as type 2 diabetes mellitus, nonalcoholic fatty liver disease, and obesity. Here, we used ultra-performance liquid chromatography (UPLC) coupled to electrospray ionization/quadrupole time-of-flight mass spectrometry (ESI-QToF) to assess the effect of chronic intergenerational As exposure on the lipid metabolism profiles of serum from 4-month-old Wistar rats exposed to As prenatally and also during early life in drinking water (3 ppm). Significant differences in the levels of certain identified lysophospholipids, phosphatidylcholines, and triglycerides were found between the exposed rats and the control groups, as well as between the sexes. Significantly increased lipid oxidation determined by the malondialdehyde (MDA) method was found in exposed rats compared with controls. Chronic intergenerational As exposure alters the rat lipidome, increases lipid oxidation, and dysregulates metabolic pathways, the factors associated with the chronic inflammation present in different diseases associated with chronic exposure to As (i.e., keratosis, Bowen's disease, and kidney, liver, bladder, and lung cancer).

Environmental neglect: endocrine disruptors as underappreciated but potentially modifiable diabetes risk factors

Type 2 diabetes prevalence is increasing dramatically across the globe, imposing a tremendous toll on individuals and healthcare systems. Reversing these trends requires comprehensive approaches to address both classical and emerging diabetes risk factors. Recently, environmental toxicants acting as endocrine-disrupting chemicals (EDCs) have emerged as novel metabolic disease risk factors. EDCs implicated in diabetes pathogenesis include various inorganic and organic molecules of both natural and synthetic origin, including arsenic, bisphenol A, phthalates, polychlorinated biphenyls and organochlorine pesticides. Indeed, evidence implicates EDC exposures across the lifespan in metabolic dysfunction; moreover, specific developmental windows exhibit enhanced sensitivity to EDC-induced metabolic disruption, with potential impacts across generations. Importantly, differential exposures to diabetogenic EDCs likely also contribute to racial/ethnic and economic disparities. Despite these emerging links, clinical practice guidelines fail to address this underappreciated diabetes risk factor. Comprehensive approaches to stem the tide of diabetes must include efforts to address its environmental drivers.

Non-monotonic dose-response effects of arsenic on glucose metabolism

BACKGROUND

Inorganic arsenic (iAs) is a widespread environmental toxin. In addition to being a human carcinogen, its effect on diabetes has started to gain recognition recently. Insulin is the key hormone regulating systemic glucose metabolism. The in vivo effect of iAs on insulin sensitivity has not been directly addressed.

OBJECTIVES

Here we use mouse models to dissect the dose-dependent effects of iAs on glucose metabolism in vivo.

METHODS

We performed hyperinsulinemic-euglycemic clamp, the gold standard analysis of systemic insulin sensitivity. We also performed dynamic metabolic testings and RNA-seq analysis.

RESULTS

We found that a low-dose exposure (0.25 ppm iAs in drinking water) caused glucose intolerance in adult male C57BL/6 mice, likely by disrupting glucose-induced insulin secretion without affecting peripheral insulin sensitivity. However, a higher-dose exposure (2.5 ppm iAs) had diminished effects on glucose tolerance despite disrupted pancreatic insulin secretion. Insulin Clamp analysis showed that 2.5 ppm iAs actually enhanced systemic insulin sensitivity by simultaneously enhancing insulin-stimulated glucose uptake in skeletal muscles and improved insulin-mediated suppression of endogenous glucose production. RNA-seq analysis of skeletal muscles revealed that 2.5 ppm iAs regulated expression of many genes involved in the metabolism of fatty acids, pyruvate, and amino acids.

CONCLUSION

These findings suggest that iAs has opposite glycemic effects on distinct metabolic tissues at different dose thresholds. Such non-monotonic dose-response effects of iAs on glucose tolerance shed light on the complex interactions between iAs and the systemic glucose metabolism, which could potentially help reconcile some of the conflicting results in human epidemiological studies.

Arsenic modifies serotonin metabolism through glucuronidation in pancreatic β-cells

In arsenic-endemic regions of the world, arsenic exposure correlates with diabetes mellitus. Multiple animal models of inorganic arsenic (iAs, as As³⁺) exposure have revealed that iAs-induced glucose intolerance manifests as a result of pancreatic β-cell dysfunction. To define the mechanisms responsible for this β-cell defect, the MIN6-K8 mouse β-cell line was exposed to environmentally relevant doses of iAs. Exposure to 0.1-1 µM iAs for 3 days significantly decreased glucose-induced insulin secretion (GIIS). Serotonin and its precursor, 5-hydroxytryptophan (5-HTP), were both decreased. Supplementation with 5-HTP, which loads the system with bioavailable 5-HTP and serotonin, rescued GIIS, suggesting that recovery of this pathway was sufficient to restore function. Exposure to iAs was accompanied by an increase in mRNA expression of UDP-glucuronosyltransferase 1 family, polypeptide a6a (Ugt1a6a), a phase-II detoxification enzyme that facilitates the disposal of cyclic amines, including serotonin, via glucuronidation. Elevated Ugt1a6a and UGT1A6 expression levels were observed in mouse and human islets, respectively, following 3 days of iAs exposure. Consistent with this finding, the enzymatic rate of serotonin glucuronidation was increased in iAs-exposed cells. Knockdown by siRNA of Ugt1a6a during iAs exposure restored GIIS in MIN6-K8 cells. This effect was prevented by blockade of serotonin biosynthesis, suggesting that the observed iAs-induced increase in Ugt1a6a affects GIIS by targeting serotonin or serotonin-related metabolites. Although it is not yet clear exactly which element(s) of the serotonin pathway is/are most responsible for iAs-induced GIIS dysfunction, this study provides evidence that UGT1A6A, acting on the serotonin pathway, regulates GIIS under both normal and pathological conditions.

Arsenic Exposure Contributes to the Bioenergetic Damage in an Alzheimer's Disease Model

Worldwide, every year there is an increase in the number of people exposed to inorganic arsenic (iAs) via drinking water. Human populations present impaired cognitive function as a result of prenatal and childhood iAs exposure, while studies in animal models demonstrate neurobehavioral deficits accompanied by neurotransmitter, protein, and enzyme alterations. Similar impairments have been observed in close association with Alzheimer's disease (AD). In order to determine whether iAs promotes the pathophysiological progress of AD, we used the 3xTgAD mouse model. Mice were exposed to iAs in drinking water from gestation until 6 months (As-3xTgAD group) and compared with control animals without arsenic (3xTgAD group). We investigated the behavior phenotype on a test battery (circadian rhythm, locomotor behavior, Morris water maze, and contextual fear conditioning). Adenosine triphosphate (ATP), reactive oxygen species, lipid peroxidation, and respiration rates of mitochondria were evaluated, antioxidant components were detected by immunoblots, and immunohistochemical studies were performed to reveal AD markers. As-3xTgAD displayed alterations in their circadian rhythm and exhibited longer freezing time and escape latencies compared to the control group. The bioenergetic profile revealed decreased ATP levels accompanied by the decline of complex I, and an oxidant state in the hippocampus. On the other hand, the cortex showed no changes of oxidant stress and complex I; however, the antioxidant response was increased. Higher immunopositivity to amyloid isoforms and to phosphorylated tau was observed in frontal cortex and hippocampus of exposed animals. In conclusion, mitochondrial dysfunction may be one of the triggering factors through which chronic iAs exposure exacerbates brain AD-like pathology.

Braving the Element: Pancreatic β-Cell Dysfunction and Adaptation in Response to Arsenic Exposure

Type 2 diabetes mellitus (T2DM) is a serious global health problem, currently affecting an estimated 451 million people worldwide. T2DM is characterized by hyperglycemia and low insulin relative to the metabolic demand. The precise contributing factors for a given individual vary, but generally include a combination of insulin resistance and insufficient insulin secretion. Ultimately, the progression to diabetes occurs only after β-cells fail to meet the needs of the individual. The stresses placed upon β-cells in this context manifest as increased oxidative damage, local inflammation, and ER stress, often inciting a destructive spiral of β-cell death, increased metabolic stress due to further insufficiency, and additional β-cell death. Several pathways controlling insulin resistance and β-cell adaptation/survival are affected by a class of exogenous bioactive compounds deemed endocrine disrupting chemicals (EDCs). Epidemiological studies have shown that, in several regions throughout the world, exposure to the EDC inorganic arsenic (iAs) correlates significantly with T2DM. It has been proposed that a lifetime of exposure to iAs may exacerbate problems with both insulin sensitivity as well as β-cell function/survival, promoting the development of T2DM. This review focuses on the mechanisms of iAs action as they relate to known adaptive and maladaptive pathways in pancreatic β-cells.

Effect of gestational exposure to arsenic on puberty in offspring female mice

We examined the vaginal opening day, ovary and uterus organ coefficient, reproductive hormone levels of luteinizing hormone (LH) and follicle stimulating hormone (FSH), mRNA and protein expression levels of kiss-1, hypothalamus gonadotrophin releasing hormone 1 (GnRH1), organic cation transporters 2 (Oct2) and transcription termination factor 1 (Ttf1) in different pubertal ages [late lactation (18 days), pre-puberty (21-22 days), puberty (23-27 days; with respect to vaginal opening) and maturity (65 days)] of offspring females, to evaluate the effect of arsenic (As) on puberty initiation after maternal exposure to As at different concentration [0, 0.15, 1.5 and 15 mg/L As(III)] during gestational period. The results showed that the vaginal opening time was significantly advanced in utero in mice exposed to As compared to the control. The hormone level of LH was significantly increased in the mice treated with 15 mg/L of As(III) at puberty compared to the control. During puberty, the mRNA expression levels of kiss-1, GnRH1, Oct2 and Ttf1 in the hypothalamus were significantly increased in the group treated with 15 mg/L of As(III) compared to the control. The protein expressions of Kisspeptin, GnRH1, Oct2 and Ttf1 in the hypothalamus were significantly increased in the pubertal females, while Oct2 and Ttf1 expression levels were significantly decreased in the matured females compared to the control, which is in line with the transcriptional changes of related mRNA expressions. In brief, this study demonstrated that maternal exposure to As during gestational period could result in early onset of puberty in offspring females.

Underutilized and Under Threat: Environmental Policy as a Tool to Address Diabetes Risk

PURPOSE OF REVIEW

Diabetes is a burgeoning threat to public health in the USA. Importantly, the burden of diabetes is not equally borne across society with marked disparities based on geography, race/ethnicity, and income. The etiology of global and population-specific diabetes risk remains incompletely understood; however, evidence linking environmental toxicants acting as endocrine-disrupting chemicals (EDCs), such as particulate matter and arsenic, with diabetes suggests that environmental policies could play an important role in diabetes risk reduction.

RECENT FINDINGS

Evidence suggests that disproportionate exposures to EDCs may contribute to subgroup-specific diabetes risk; however, no federal policies regulate EDCs linked to diabetes based upon diabetogenic potential. Nevertheless, analyses of European Union data indicate that such regulation could reduce diabetes-associated costs and disease burden. Federal laws only regulate EDCs indirectly. The accumulating evidence linking these chemicals with diabetes risk should encourage policymakers to adopt stricter environmental standards that consider both health and economic impacts.