Association of urinary concentrations of bisphenol A and phthalate metabolites with risk of type 2 diabetes: a prospective investigation in the Nurses' Health Study (NHS) and NHSII cohorts

Effect of Rinsing Canned Foods on Bisphenol-A Exposure: The Hummus Experiment

Bisphenol-A (BPA) is associated with adverse health outcomes and is found in many canned foods. It is not understood if some BPA contamination can be washed away by rinsing. The objective of this single-blinded crossover experiment was to determine whether BPA exposure, as measured by urinary concentrations, could be decreased by rinsing canned beans prior to consumption. Three types of hummus were prepared from dried beans, rinsed, and unrinsed canned beans. Fourteen healthy participants ate two samples of each hummus over six experimental days and collected spot urine specimens for BPA measurement. The geometric mean BPA levels for dried beans BPA (GM = 0.97 ng/ml, 95%CI = 0.74,1.26) was significantly lower than rinsed (GM = 1.89 ng/ml, 1.37,2.59) and unrinsed (GM = 2.46 ng/ml, 1.44,4.19). Difference-in-difference estimates showed an increase in GM BPA from pre- to post-hummus between unrinsed and rinsed canned beans of 1.39 ng/ml, p-value = 0.0400. Rinsing canned beans was an effective method to reduce BPA exposure.

Environmental Endocrine-Disrupting Chemical Exposure: Role in Non-Communicable Diseases

The exponential growth of pollutant discharges into the environment due to increasing industrial and agricultural activities is a rising threat for human health and a biggest concern for environmental health globally. Several synthetic chemicals, categorized as potential environmental endocrine-disrupting chemicals (EDCs), are evident to affect the health of not only livestock and wildlife but also humankind. In recent years, human exposure to environmental EDCs has received increased awareness due to their association with altered human health as documented by several epidemiological and experimental studies. EDCs are associated with deleterious effects on male and female reproductive health; causes diabetes, obesity, metabolic disorders, thyroid homeostasis and increase the risk of hormone-sensitive cancers. Sewage effluents are a major source of several EDCs, which eventually reach large water bodies and potentially contaminate the drinking water supply. Similarly, water storage material such as different types of plastics also leaches out EDCs in drinking Water. Domestic wastewater containing pharmaceutical ingredients, metals, pesticides and personal care product additives also influences endocrine activity. These EDCs act via various receptors through a variety of known and unknown mechanisms including epigenetic modification. They differ from classic toxins in several ways such as low-dose effect, non-monotonic dose and trans-generational effects. This review aims to highlight the hidden burden of EDCs on human health and discusses the non-classical toxic properties of EDCs in an attempt to understand the magnitude of the exposome on human health. Present data on the environmental EDCs advocate that there may be associations between human exposure to EDCs and several undesirable health outcomes that warrants further human bio-monitoring of EDCs.

Urinary Concentrations of Bisphenols in the Australian Population and Their Association with the Per Capita Mass Loads in Wastewater

Health concerns and related regulation of bisphenol A (BPA) in some countries have led to an increase in the production and use of unregulated and poorly understood BPA analogues, including bisphenol S (BPS), bisphenol F (BPF), bisphenol B (BPB), and bisphenol AF (BPAF). To assess the temporal trends of human exposure to BPA analogues, urine and wastewater samples were collected from South East Queensland, Australia between 2012 and 2017 and analyzed for five bisphenols using validated isotope dilution liquid chromatography tandem mass spectrometry methods. BPA and BPS were the predominant bisphenols detected in both urine and wastewater samples, with median concentrations of 2.5 and 0.64 μg/L in urine and 0.94 and 1.1 μg/L in wastewater, respectively. BPB, BPF, and BPAF had low detection frequencies in both urine and wastewater samples. Concentrations of BPA in both urine and wastewater decreased over the sampling period, whereas concentrations of BPS increased, suggesting that BPS has become a BPA replacement. The contributions of urinary excretion to wastewater were calculated by the ratio of daily per capita urinary excretion to wastewater-based mass loads of bisphenols. Urinary BPA and BPS contributed to less than 1% of the load found in wastewater, indicating that much of the BPA and BPS originates from other sources.

Association Between Bisphenol A Exposure and Risk of All-Cause and Cause-Specific Mortality in US Adults

IMPORTANCE

Bisphenol A (BPA) is a major public health concern because of its high-volume industrial production, ubiquitous exposure to humans, and potential toxic effects on multiple organs and systems in humans. However, prospective studies regarding the association of BPA exposure with long-term health outcomes are sparse.

OBJECTIVE

To examine the association of BPA exposure with all-cause mortality and cause-specific mortality among adults in the United States.

DESIGN, SETTING, AND PARTICIPANTS

This nationally representative cohort study included 3883 adults aged 20 years or older who participated in the US National Health and Nutrition Examination Survey 2003-2008 and provided urine samples for BPA level measurements. Participants were linked to mortality data from survey date through December 31, 2015. Data analyses were conducted in July 2019.

EXPOSURES

Urinary BPA levels were quantified using online solid-phase extraction coupled to high-performance liquid chromatography-isotope dilution tandem mass spectrometry.

MAIN OUTCOMES AND MEASURES

Mortality from all causes, cardiovascular disease, and cancer.

RESULTS

This cohort study included 3883 adults aged 20 years or older (weighted mean [SE] age, 43.6 [0.3] years; 2032 women [weighted, 51.4%]). During 36 514 person-years of follow-up (median, 9.6 years; maximum, 13.1 years), 344 deaths occurred, including 71 deaths from cardiovascular disease and 75 deaths from cancer. Participants with higher urinary BPA levels were at higher risk for death. After adjustment for age, sex, race/ethnicity, socioeconomic status, dietary and lifestyle factors, body mass index, and urinary creatinine levels, the hazard ratio comparing the highest vs lowest tertile of urinary BPA levels was 1.49 (95% CI, 1.01-2.19) for all-cause mortality, 1.46 (95% CI, 0.67-3.15) for cardiovascular disease mortality, and 0.98 (95% CI, 0.40-2.39) for cancer mortality.

CONCLUSIONS AND RELEVANCE

In this nationally representative cohort of US adults, higher BPA exposure was significantly associated with an increased risk of all-cause mortality. Further studies are needed to replicate these findings in other populations and determine the underlying mechanisms.

Endocrine-disrupting chemicals: implications for human health

Since reports published in 2015 and 2016 identified 15 probable exposure-outcome associations, there has been an increase in studies in humans of exposure to endocrine-disrupting chemicals (EDCs) and a deepened understanding of their effects on human health. In this Series paper, we have reviewed subsequent additions to the literature and identified new exposure-outcome associations with substantial human evidence. Evidence is particularly strong for relations between perfluoroalkyl substances and child and adult obesity, impaired glucose tolerance, gestational diabetes, reduced birthweight, reduced semen quality, polycystic ovarian syndrome, endometriosis, and breast cancer. Evidence also exists for relations between bisphenols and adult diabetes, reduced semen quality, and polycystic ovarian syndrome; phthalates and prematurity, reduced anogenital distance in boys, childhood obesity, and impaired glucose tolerance; organophosphate pesticides and reduced semen quality; and occupational exposure to pesticides and prostate cancer. Greater evidence has accumulated than was previously identified for cognitive deficits and attention-deficit disorder in children following prenatal exposure to bisphenol A, organophosphate pesticides, and polybrominated flame retardants. Although systematic evaluation is needed of the probability and strength of these exposure-outcome relations, the growing evidence supports urgent action to reduce exposure to EDCs.

Bisphenol A-induced metabolic disorders: From exposure to mechanism of action

Bisphenol A (BPA) is considered as ubiquitous xenooestrogen and an endocrine disrupting chemical which has deleterious effects on endocrine functions. Human populations are continuously exposed to BPA as it is abundant in daily life. It has been found to be associated with wide range of metabolic disorders notably type 2 diabetes mellitus (DM). Numerous epidemiological studies have been conducted to find its role in development of DM. Experimental studies have found that BPA exposure is associated with pathogenesis of DM and also considered as a risk factor for gestational diabetes. Being a lipophilic compound, BPA is preferably accumulated in adipose tissues where it alters the production of adipokines that play important roles in insulin resistance. BPA induces apoptosis by caspase activation after mitochondrial damage and it impairs insulin signaling pathways by altering associated ion channel activity especially potassium channels. Perinatal exposure of BPA makes offspring more susceptible to develop DM in early years. Epigenetic modifications are the key mechanisms for BPA-induced metabolic re-programming, where BPA alters the expression of DNA methyltransferases involved in methylation of various genes. In this way, DNA methyltransferase controls the expression of numerous genes including genes important for insulin secretion and signaling. Furthermore, BPA induces histone modifications and alters miRNA expression. In this article, we have briefly described the sources of BPA exposure to human being and summarized the evidence from epidemiological studies linking DM with BPA exposure. Additionally, we have also highlighted the potential molecular pathways for BPA-induced DM.

Exposure to Endocrine Disrupting Chemicals in the Dutch general population is associated with adiposity-related traits

Endocrine Disrupting Chemicals (EDCs) have been linked to a variety of cardiometabolic diseases. Yet, few studies have investigated the exposure to EDCs and cardiometabolic health taking lifestyle into account. We aimed to assess exposure to five parabens, three bisphenols and thirteen metabolites of in total eight phthalates in a general Dutch population and to investigate their association with cardiometabolic traits. In 662 adult subjects from the population-based Lifelines cohort, 21 EDC analytes were measured in 24-hour urine collected in 2012, using LC-MS/MS. Association analyses between cardiometabolic traits and EDC concentrations were performed using multivariate linear models adjusting for age, sex, education, smoking, diabetes, physical activity and caloric intake. Quartile analyses were performed to assess linearity. Bisphenol A, four parabens and eight phthalate metabolites were detected in 84-100% of the samples. Adjusted associations for MiBP and MBzP and adiposity-related traits were robust for multiple testing (Beta’s, BMI: 1.12, 2.52; waist circumference: 0.64, 1.56, respectively; FDR < 0.009). Associations for triglyceride, HDL-cholesterol, glucose and blood pressure were not. Linearity was confirmed for significant associations. Exposure to EDCs in the Dutch population is ubiquitous. We found direct associations between phthalates and adiposity-related traits. Prospective studies are needed to confirm these findings.

Urinary phenols and parabens and diabetes among US adults, NHANES 2005-2014

BACKGROUND AND AIMS

Phenols and parabens are ubiquitous and have been associated with markers of cardiovascular health. However, the literature lacks population-based studies examining the link between these endocrine disruptors and diabetes. We examined the association between paraben/phenol concentrations and diabetes among a nationally representative sample of US adults.

METHODS AND RESULTS

We utilized data from the 2005-2014 National Health and Nutrition Examination Surveys (N = 8498). Total urinary concentrations of BPA, triclosan, BP-3, and propyl, butyl, ethyl, and methyl parabens were measured from urine specimens collected during the examination session. Diabetes status was based on self-report of a previous diagnosis or HbA1c≥6.5%. We used logistic regression to estimate odds ratios (ORs) and 95% confidence intervals (CI) associated with the difference in log-transformed values of the 75th and 25th percentiles for each phenol/paraben, adjusting for potential confounders. The adjusted ORs (95% CI) of diabetes comparing the 75th to 25th percentiles of each paraben/phenol were 1.09 (0.96-1.23) for BPA, 0.84 (0.72-0.98) for triclosan, 0.69 (0.61-0.79) for BP-3, 0.71 (0.61-0.83) for propyl paraben, 0.66 (0.54-0.80) for butyl paraben, 0.60 (0.51-0.71) for ethyl paraben, and 0.79 (0.68-0.91) for methyl paraben.

CONCLUSIONS

Higher concentrations of triclosan, BP-3, and propyl, butyl, ethyl, and methyl parabens were associated with lower odds of diabetes. These findings warrant further investigation into the potential mechanism behind the observed associations and the temporal direction of the associations, given that we cannot rule out reverse causation. Future studies of these endocrine disruptors may improve the understanding of their relationship with diabetes.

Rationale and design of a randomized controlled trial examining oral administration of bisphenol A on hepatic glucose production and skeletal muscle insulin sensitivity in adults

Previous observational studies have shown that the endocrine disrupting chemical bisphenol A (BPA) is associated with type 2 diabetes, but few studies have examined direct effects of BPA on human health. The purpose of this study is to determine whether orally administered BPA at the US Environmental Protection Agency (EPA) safe dose of 50 μg/kg body weight has an adverse effect on hepatic glucose production and skeletal muscle insulin sensitivity. Forty, non-habitually active, healthy adults of normal weight will be enrolled. Participants will begin with a 2-day baseline energy balance diet low in bisphenols in which urine and blood will be collected, and standard tests performed to assess the primary outcome measures of hepatic glucose production (via [6,6-²H] glucose infusion) and skeletal muscle insulin sensitivity (via euglycemic hyperinsulinemic clamp technique). Secondary outcome measures are fasting hormones/endocrine factors (insulin, glucose, C-peptide, Pro-insulin, adiponectin, 17-beta-estradiol, free fatty acids) related to the pathogenesis of type 2 diabetes. Participants will then be randomly assigned to a 4-day energy balance diet plus oral administration of BPA at 50 μg/kg body weight (Diet + BPA) or 4-day energy balance diet plus oral administration of placebo (Diet + No BPA); all outcome measures will be reassessed after 4 days. Findings from this study will provide a framework for other studies in this area, and provide much needed experimental evidence using gold standard measures as to whether oral BPA administration over several days poses any risk of type 2 diabetes.

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Bisphenol A is associated with type 2 diabetes.

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Few studies have examined oral bisphenol A administration on the pathogenesis of type 2 diabetes.

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This study will examine oral bisphenol A administration on hepatic glucose [6,6-²H] suppression.

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This study will examine insulin sensitivity (euglycemic hyperinsulinemic clamp technique).

Diabetes and Toxicant Exposure

The worldwide prevalence of obesity has near tripled between 1975 and 2016. Diabetes was the direct cause of an estimated 1.6 million deaths in 2015. Diabetogens, otherwise known as toxicants that cause insulin resistance in animal models and humans as a result of pancreatic β-cell damage include the persistent organochlorine pesticides trans-nonachlor, oxychlordane, and DDE -the main metabolite of DDT, as well as another class of persistent organic pollutants, polychlorinated biphenyls (PCBs). Other toxicants that are now considered diabetogens: BPA, arsenic, phthalates, perfluorinates (PFOS), diethyl hexyl phthalate (DEHP), and dioxin (TCDD) are commonly found in the blood and urine in the CDC NHANES populations and presumed to also be commonly found in the U.S. population as a whole. A review of the literature on the risk for diabetes in epidemiologic studies considering these toxicants, challenges for clinicians using lab testing for these diabetogens, and the necessary interventions for lowering body burden of persistent toxicants are discussed.

In utero Bisphenol A Exposure Is Linked with Sex Specific Changes in the Transcriptome and Methylome of Human Amniocytes

CONTEXT

Prenatal exposure to bisphenol A (BPA) is linked to obesity and diabetes but the molecular mechanisms driving these phenomena are not known. Alterations in deoxyribonucleic acid (DNA) methylation in amniocytes exposed to BPA in utero represent a potential mechanism leading to metabolic dysfunction later in life.

OBJECTIVE

To profile changes in genome-wide DNA methylation and expression in second trimester human amniocytes exposed to BPA in utero.

DESIGN

A nested case-control study was performed in amniocytes matched for offspring sex, maternal race/ethnicity, maternal age, gestational age at amniocentesis, and gestational age at birth. Cases had amniotic fluid BPA measuring 0.251 to 23.74 ng/mL. Sex-specific genome-wide DNA methylation analysis and RNA-sequencing (RNA-seq) were performed to determine differentially methylated regions (DMRs) and gene expression changes associated with BPA exposure. Ingenuity pathway analysis was performed to identify biologically relevant pathways enriched after BPA exposure. In silico Hi-C analysis identified potential chromatin interactions with DMRs.

RESULTS

There were 101 genes with altered expression in male amniocytes exposed to BPA (q < 0.05) in utero, with enrichment of pathways critical to hepatic dysfunction, collagen signaling and adipogenesis. Thirty-six DMRs were identified in male BPA-exposed amniocytes and 14 in female amniocyte analysis (q < 0.05). Hi-C analysis identified interactions between DMRs and 24 genes with expression changes in male amniocytes and 12 in female amniocytes (P < 0.05).

CONCLUSION

In a unique repository of human amniocytes exposed to BPA in utero, sex-specific analyses identified gene expression changes in pathways associated with metabolic disease and novel DMRs with potential distal regulatory functions.

Urine Bisphenol A and Arsenic Levels in Residents of the Cheyenne River Sioux Tribe, South Dakota, with and without Diabetes

INTRODUCTION

Diabetes disproportionately affects American Indians/Alaskan Natives (AI/AN). Bisphenol A (BPA) and arsenic (As), environmental toxicants which may be associated with diabetes, have not been well studied in this population. Our objectives were to determine if urinary BPA and As are associated with diabetes among adults in the Cheyenne River Sioux Tribe (CRST), and to compare their urinary levels with the general US population.

METHODS

We performed a case-control study among 276 volunteers. We matched our cases (persons with diabetes) and controls (persons without diabetes) using age. We collected questionnaire data and urine samples which were tested for BPA and speciated As analytes. We used paired t tests and McNemar's chi-square test to compare continuous and categorical variables, respectively, between cases and controls and linear regression to assess the association between self-reported exposures and BPA and As levels. We used conditional logistic regression to investigate the association between case status and BPA and As levels. BPA and As levels among participants were compared with those from the 2011-2012 National Health and Nutrition Examination Survey (NHANES).

RESULTS

The average age of participants was 46 years. The majority identified as AI/AN race (97%) and 58% were female. The geometric means from CRST participant urine specimens were 1.83 ug/L for BPA and 3.89 ug/L for total As. BPA geometric means of CRST participants were higher than NHANES participants while total As geometric means were lower. BPA and As were not associated with case status.

CONCLUSION

The results of this study are consistent with others that have reported no association between diabetes and exposure to BPA or As.

Oral intake exposure to phthalates in vegetables produced in plastic greenhouses and its health burden in Shaanxi province, China

Phthalate exposure from Vegetables grown in Plastic Greenhouses (VPGs) represents an important source of total daily phthalate exposure in China. However, quantified health risks of phthalates attributable to VPG intake have not been documented. To fill this gap, this study estimates phthalate exposure from VPG intake in western China and calculates the first assessment of the disease burden associated with phthalate exposure from VPG intake in China based on a simple steady-state exposure model and a linear dose-response function between human bio-monitoring phthalates and Type 2 Diabetes (T2D) prevalence. What we present in this paper is a problem identification and screening level risk assessment. We chose Shaanxi province as the research field site due to its large contribution to the total vegetable yield and consumption in western China. Phthalate concentration in VPG samples, phthalate exposure levels from VPG intake, and the T2D burden caused by phthalate attributable to VPG intake for adults were measured or calculated. Di-2-ethylhexyl phthalate (DEHP) was found to represent over 55% of the total phthalate concentration in VPGs, followed by di-n-butyl phthalate (DnBP) and di-isobutyl phthalate (DiBP). Phthalate exposure from VPG intake for urban adults was higher than the level for rural adults. The share of DEHP exposure from VPG intake to urinary total DEHP metabolites were nearly 8% and 15%, and the share of DnBP exposure caused by VPG intake to total daily DnBP metabolites were nearly 4% and 7%, for rural and urban adult populations in Shaanxi, respectively. The adult population with T2D attributable to phthalate exposure from VPG intake was 2561, nearly 6.4% to the T2D burden attributable to total phthalate exposure, and 0.4% to the total adult population with T2D in Shaanxi. The authors recommend policy interventions to protect populations from future risk of phthalate exposure.

Serum beta-carotene modifies the association between phthalate mixtures and insulin resistance: The National Health and Nutrition Examination Survey 2003-2006

Animal models suggest a protective role of antioxidants against the adverse effect of di-2-ethylhexyl phthalate (DEHP) on insulin resistance. However, no epidemiologic study has examined the effects observed in the animal model. We conduct a study to examine associations of urinary concentrations of phthalate metabolites (individually and as a mixture) with insulin resistance, along with potential effect modification by serum antioxidant concentrations. This cross-sectional study included 1605 participants (51% males) aged 12-85 from the National Health and Nutrition Examination Surveys (2003-2006). Urinary concentrations of 9 phthalate metabolites were measured from spot urine samples. Antioxidant (vitamin A, C, E, and carotenoids) concentrations were measured from a fasting serum sample. We used Bayesian Kernel Machine Regression (BKMR) to evaluate associations between phthalate metabolite mixtures and insulin resistance, and examined whether serum antioxidant levels modified these associations, while accounting for the correlations of multiple concurrent exposures. A change in urinary ΣDEHP concentrations from the 25th to the 75th percentile was associated with a higher log HOMA-IR of 0.07 (95% CI = 0.01, 0.14) (4.85% increase in HOMA-IR). In contrast, the same change in urinary monoethyl phthalate (MEP) was associated with a lower HOMA-IR of -0.07 (95% CI = -0.14, -0.02) (6.68% decrease in HOMA-IR). The positive association between ΣDEHP and HOMA-IR became weaker at higher concentrations of serum β-carotene. The relationship between MEP and HOMA-IR, however, was not modified by the serum antioxidants examined. The remaining phthalate metabolites were unrelated to HOMA-IR. In this cross-sectional study, the positive association between DEHP exposure and insulin resistance weakened among participants with higher concentrations of serum β-carotene. As this is the first human report on the protective role of serum β-carotene on DEHP induced insulin resistance, future studies are needed.

Phthalate exposure and metabolic effects: a systematic review of the human epidemiological evidence

OBJECTIVE

We performed a systematic review of the epidemiology literature to identify the metabolic effects associated with phthalate exposure.

DATA SOURCES AND STUDY ELIGIBILITY CRITERIA

Six phthalates were included in the review: di(2‑ethylhexyl) phthalate (DEHP), diisononyl phthalate (DINP), dibutyl phthalate (DBP), diisobutyl phthalate (DIBP), butyl benzyl phthalate (BBP), and diethyl phthalate (DEP). The initial literature search (of PubMed, Web of Science, and Toxline) included all studies of metabolic effects in humans, and outcomes were selected for full systematic review based on data availability.

STUDY EVALUATION AND SYNTHESIS METHODS

Studies of diabetes and insulin resistance were evaluated using criteria defined a priori for risk of bias and sensitivity by two reviewers using a domain-based approach; studies identified with a pre-defined critical deficiency were excluded. Evidence was synthesized by outcome and phthalate and strength of evidence was summarized using a structured framework. Studies of obesity and renal effects received "screening level" reviews to determine whether full systematic review was warranted.

RESULTS

The primary outcomes reviewed here are (number of included/excluded studies in parentheses): type 2 diabetes (1/3), insulin resistance (13/3), and impaired glucose tolerance and blood glucose in pregnancy (4/2). For DEHP exposure, there was consistency among studies of insulin resistance and coherence with the single included study of diabetes, as well as an observed exposure-response gradient observed in a study of insulin resistance. This evidence is considered moderate. Similarly, for DBP and DIBP exposure, the evidence is considered moderate due to strong positive associations in the diabetes study and coherent results for insulin resistance. For DINP, BBP, and DEP, the evidence is considered slight. No association was reported in the single study of diabetes with BBP and DEP exposure (DINP was not investigated). The available evidence does indicate an association between exposure to these phthalates and insulin resistance, but the small number of studies and the lack of coherence with diabetes decreases confidence. The screening level reviews for obesity and renal effects determined that the currently available evidence is inadequate to assess the associations between these outcomes and phthalate exposure.

CONCLUSIONS AND IMPLICATIONS OF KEY FINDINGS

Overall, these results support that phthalate exposure at levels seen in human populations may have metabolic effects. Given the mechanistic support, the large effect sizes for incident diabetes in the single available study, and the coherence with insulin resistance, the association between phthalate exposure and diabetes risk should be considered when assessing the risks and costs of exposure to specific phthalates in humans. The views expressed are those of the authors and do not necessarily represent the views or policies of the U.S. EPA.

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.

Exposure to bisphenol A and diabetes risk in Mexican women

Bisphenol A (BPA) is an endocrine-disrupting chemical widely used in the production of polycarbonate plastics and epoxy resins, which has been previously linked to diabetes among non-Hispanic populations. As part of a case control study for breast cancer, only controls with BPA information were included in this report. The final sample size comprises 70 self-reported diabetics and 334 non-diabetics. Urinary free bisphenol A (BPA-F) (μg/L) was determined by solid-phase extraction and HPLC/FLD analysis. Logistic regression models were used to evaluate the association between BPA-F and self-reported diabetes. After adjusting by age, urinary BPA-F (4.06-224.53 μg/g creatinine) was associated with diabetes exposure (OR = 1.85; 95% CI 1.04, 3.28) compared with women in the reference category (0.67-4.05 μg/g creatinine). BPA may be an environmental cofactor of diabetes. More studies are needed to confirm this result, especially in Hispanic populations.

Urinary bisphenol A concentration and glucose homeostasis in non-diabetic adults: a repeated-measures, longitudinal study

AIMS/HYPOTHESIS

Bisphenol A (BPA) has been shown to be potentially associated with type 2 diabetes; however, there is little evidence associating BPA exposure with glucose metabolic outcomes prior to diabetes onset. We aimed to examine BPA exposure in relation to glucose homeostasis among non-diabetic individuals.

METHODS

This longitudinal cohort study comprised 2336 Chinese adults aged 40 years or above (62.8% women) and free of diabetes at baseline in 2009, followed for 4 years. Urinary BPA and glucose metabolic traits including fasting plasma glucose (FPG), 2 h post-load plasma glucose, fasting serum insulin, HOMA-IR and HOMA-B were measured at baseline and follow-up. Repeated-measures analysis was performed to evaluate associations of urinary BPA concentration with markers of glucose homeostasis.

RESULTS

After full adjustment for confounders including BMI, each tenfold increase in urinary BPA concentrations was associated with a 3.39% increase in FPG (95% CI 2.24%, 4.55%) and an 11.6% decrease in HOMA-B (95% CI -15.8%, -7.18%) in women. The inverse association between urinary BPA and HOMA-B was more prominent among overweight or obese individuals (change -13.7%; 95% CI -19.3%, -7.61%) compared with those who were of normal weight (change -6.74%; 95% CI -13.2%, 0.20%) (p_interaction = 0.07). Moreover, the ORs of fasting hyperglycaemia and beta cell dysfunction corresponding to a tenfold increase in urinary BPA concentrations were 1.37 (95% CI 1.10, 1.72) and 1.30 (95% CI 1.02, 1.65) in women, respectively. No significant associations existed between urinary BPA and glucose metabolic markers in men.

CONCLUSIONS/INTERPRETATION

Our findings suggest that exposure to BPA was independently associated with impaired glucose homeostasis before the development of diabetes in middle-aged and elderly women.

Urinary bisphenol A and incidence of metabolic syndrome among Chinese men: a prospective cohort study from 2013 to 2017

OBJECTIVES

Experimental studies suggested that bisphenol A (BPA) exposure increased the risk of metabolic syndrome (MetS) through the mechanism of insulin resistance. All previous epidemiological studies of BPA and MetS were cross-sectional studies, and their findings were mixed. This study aims to provide further evidence on the association between urinary BPA and risk of MetS using a prospective cohort study in China.

METHODS

The study population was from the Shenzhen Night shift workers' cohort. A total of 1227 male workers were recruited from the baseline survey in 2013 and then followed until 2017. Modified Adult Treatment Panel III criteria were used to identify the cases of MetS. Urinary BPA concentration was assessed using high-performance liquid chromatography-tandem mass spectrometry, and it was categorised into three subgroups by tertiles to obtain the adjusted HR (aHR) and 95% CI using Cox proportional hazard model.

RESULTS

During 4 years of follow-up, 200 subjects developed MetS. Compared with the lowest urinary BPA subgroup, a weakly increased risk of MetS was suggested among those with the middle (aHR=1.19, 95% CI 0.87 to 1.63) and high level of urinary BPA (aHR=1.16, 95% CI 0.84 to 1.59); however, the significant association with MetS was restricted primarily to the smokers, showing a positive gradient with urinary BPA (middle level: aHR=2.40, 95% CI 1.13 to 5.08; high level: aHR=2.87, 95% CI 1.38 to 5.98; p trend= 0.010).

CONCLUSION

This prospective cohort study provided further evidence that exposure to BPA may increase the risk of MetS, and this association was further positively modified by cigarette smoking.

Bisphenol A, Chlorinated Derivatives of Bisphenol A and Occurrence of Myocardial Infarction in Patients with Type 2 Diabetes: Nested Case-Control Studies in Two European Cohorts

A positive association between Bisphenol A (BPA) exposure and coronary heart disease has been shown, but not in patients with type 2 diabetes (T2D). During the treatment of drinking water, chlorination leads to the formation of chlorinated derivatives of Bisphenol A (ClxBPA), that have higher estrogenic activity than BPA. No evidence exists for a relationship between exposure to ClxBPA and myocardial infarction in patients with T2D. The objective of this study was to evaluate the relationship between exposure to BPA, ClxBPA and the occurrence of myocardial infarction (MI) in patients with T2D. Two nested case-control studies in two independent European cohorts were performed. Each case with incident MI during follow-up was matched to one control on age, sex, and personal cardiovascular history in the same cohort. Association between baseline urine concentrations of BPA and of ClxBPA and incident MI was determined. Exposure to BPA was 31% in the ESTHER cohort and 18% in the SURDIAGENE cohort. In a meta-analysis of the two studies, occurrence of MI was significantly associated with urine BPA detection: adjusted OR = 1.97 (1.05-3.70), p = 0.04. Exposure to ClxBPA significantly differed in the SURDIAGENE and ESTHER studies: 24% and 8%, respectively (p = 0.0003). It was very strongly associated with MI in the SURDIAGENE cohort with an adjusted odds ratio (OR) of 14.15 (2.77-72.40) but this association was not replicated in the ESTHER study: adjusted OR: 0.17 (0.02-1.23). Whether these results may be explained by different water chlorination processes in France and Germany, resulting in different ClxBPA exposure levels, requires further investigation.

Phthalate exposure increases subclinical atherosclerosis in young population

The link between phthalate exposure and the risk of subclinical atherosclerosis in young population remains unclear. This study investigated the association between phthalate exposure and subclinical atherosclerosis, in terms of carotid intima-media thickness (CIMT), in young population. From a nationwide mass urine screening for renal health, conducted in 1992-2000 among school children 6-18 years of age in Taiwan, we recruited 789 subjects to participate in the cardiovascular health examination in 2006-2008. Among them, 787 received measurements of 7 urinary phthalate metabolites and CIMT. Results showed both mean and maximal values of CIMT at all segments of carotid arteries significantly increased with the urinary mono-2-ethylhexyl phthalate (MEHP), ∑ di-(2-ethylhexyl) phthalate (DEHP), and mono-n-butyl phthalate (MnBP) in a dose-response relationship after adjustment for multiple linear regression models. Multivariate logistic regression analysis showed that higher quartiles of urinary concentrations of MEHP, ∑DEHP, and MnBP were associated with a higher risk of thicker CIMT. Compared to subjects with the lowest quartile (Q1) of urinary MEHP, the adjusted odds ratios (95% confidence interval) for thicker CIMT among subjects with higher urinary MEHP were 2.13 (1.18-3.84) at Q2, 4.02 (2.26-7.15) at Q3 and 7.39 (4.16-13.12) at the highest Q4. In conclusion, urinary phthalate metabolites of MEHP, ∑DEHP, and MnBP are strongly associated with CIMT in adolescents and young adults in Taiwan.

Association between phthalate exposure and glycosylated hemoglobin, fasting glucose, and type 2 diabetes mellitus: A case-control study in China

Epidemiological studies have shown that exposure to phthalates (PAEs) is associated with type 2 diabetes mellitus (T2DM) and related markers, but limited evidence has been found in Chinese people. Given that China has the highest number of people with DM and Chinese people show relatively higher exposure levels of PAEs, a case-control study was conducted in China to explore the associations of PAE exposure with T2DM and two glycemic indicators, including fasting glucose and glycosylated hemoglobin (HbA1c). Two hundred fifty people with T2DM and 250 controls were recruited in this study. Multivariable logistic regression analyses showed significant positive associations between urinary concentrations of most studied PAE metabolites (mPAEs) and T2DM, with odd ratios comparing extreme mPAEs quartiles ranging from 2.09 to 40.53, whereas two secondary metabolites, mono (2-ethyl-5-carboxypentyl) phthalate and mono [(2-carboxymethyl) hexyl] phthalate showed significant inverse relationships with T2DM. In addition, multivariable linear regression analyses showed that urinary concentrations of mono (2-ethyl-5-hydroxyhexyl) phthalate were positively associated with HbA1c levels in controls (β = 0.013; 95% CI: 0.003, 0.023). A significant positive association was also observed for urinary mono (2-ethylhexyl) phthalate and fasting glucose (β = 0.009; 95% CI: 0.002, 0.016). In the stratified analyses, the significant associations of mPAEs with T2DM were more likely to be observed in the younger people, compared to the older people. The significant positive associations between urinary mPAEs and HbA1c levels were more likely to be found in the lower body mass index (BMI) subgroup. Additionally, urinary specific mPAEs were found to be significantly positively related to fasting glucose in males and the older people. The findings suggest that exposure to PAEs is associated with T2DM, fasting glucose, and HbA1c levels in Chinese people and the associations of exposure to PAEs with T2DM, fasting glucose, and HbA1c may differ between sexes, BMIs, or ages.

Mediation analysis for the relationship between urinary phthalate metabolites and type 2 diabetes via oxidative stress in a population in Jeddah, Saudi Arabia

Human exposure to phthalates is ubiquitous and has received considerable attention due to their association with adverse health outcomes, including type 2 diabetes mellitus (T2DM). Nevertheless, earlier studies that link phthalate exposure to T2DM yielded ambiguous results. Furthermore, studies that associate phthalate exposure with oxidative stress and then with T2DM are scant. In this diabetic case-control study, urine samples collected from 101 individuals aged 28-68 years from Jeddah, Saudi Arabia, were analyzed to determine 20 phthalate metabolites (PhMs) and seven oxidative stress biomarkers (OSBs). Unconditional logistic regression was used to estimate odds ratios for the association between diabetes and urinary PhMs and OSBs in participants, stratified by age, gender, nationality, smoking status, occupation, and urinary creatinine. Twelve PhMs and five OSBs were found at detection rates above 50%, with geometric mean concentrations of 0.61-100 and 0.35-10.7 ng/mL (1.04-171 and 0.61-18.6 μg/g creatinine), respectively. Almost all exposures were significantly higher in diabetic cases than in controls. The 12 PhMs were positively associated with higher urinary concentrations of 8-hydroxy-2'-deoxyguanosine (8-OHdG) and 8-iso-prostaglandin F_2α (8-PGF_2α). Individuals in the 3rd and/or 4th quartile(s) for urinary concentrations of PhMs and OSBs showed 3.7- and 7.3-fold increase, respectively, in the odds of having diabetes compared with those in the 1st quartile. The rank order of association of PhMs/OSBs with diabetes followed the order of: mEP ≈ mBP > mEHP > mCPP > mECPP ≈ mEOHP ≈ mEHHP ≈ mIBP ≈ mMP > mCMHP ≈ mBzP and 8-OHdG > 8-PGF_2α ≈ 15-PGF_2α. The relationship between phthalate exposure and risk of developing T2DM was mediated in part by phthalate-induced oxidative stress, especially 8-OHdG. Our study suggests that human exposure to phthalates is associated with increased oxidative stress which mediates the development of T2DM.

A Review of Biomonitoring of Phthalate Exposures

Phthalates (diesters of phthalic acid) are widely used as plasticizers and additives in many consumer products. Laboratory animal studies have reported the endocrine-disrupting and reproductive effects of phthalates, and human exposure to this class of chemicals is a concern. Several phthalates have been recognized as substances of high concern. Human exposure to phthalates occurs mainly via dietary sources, dermal absorption, and air inhalation. Phthalates are excreted as conjugated monoesters in urine, and some phthalates, such as di-2-ethylhexyl phthalate (DEHP), undergo secondary metabolism, including oxidative transformation, prior to urinary excretion. The occurrence of phthalates and their metabolites in urine, serum, breast milk, and semen has been widely reported. Urine has been the preferred matrix in human biomonitoring studies, and concentrations on the order of several tens to hundreds of nanograms per milliliter have been reported for several phthalate metabolites. Metabolites of diethyl phthalate (DEP), dibutyl- (DBP) and diisobutyl- (DiBP) phthalates, and DEHP were the most abundant compounds measured in urine. Temporal trends in phthalate exposures varied among countries. In the United States (US), DEHP exposure has declined since 2005, whereas DiNP exposure has increased. In China, DEHP exposure has increased since 2000. For many phthalates, exposures in children are higher than those in adults. Human epidemiological studies have shown a significant association between phthalate exposures and adverse reproductive outcomes in women and men, type II diabetes and insulin resistance, overweight/obesity, allergy, and asthma. This review compiles biomonitoring studies of phthalates and exposure doses to assess health risks from phthalate exposures in populations across the globe.

Pilot Study on the Effect of Orally Administered Bisphenol A on Glucose and Insulin Response in Nonobese Adults

OBJECTIVE

To determine the effects of varying doses of orally administered BPA on indices of glucose metabolism.

METHODS

Eleven college students (21.0 ± 0.8 years; 24.2 ± 3.9 kg/m2) were randomized in a double-blinded, crossover fashion separated by >1 week to placebo (PL), deuterated BPA at 4 µg/kg body weight (BPA-4), and deuterated BPA at 50 µg/kg body weight (BPA-50). Total BPA, glucose, insulin, and C-peptide were assessed at baseline, minutes 15, 30, 45, 60, and every 30 minutes for 2 hours in response to a glucose tolerance test.

RESULTS

There was a significant condition × time interaction for total BPA (P < 0.001) such that BPA increased more rapidly in BPA-50 than BPA-4 and PL (P = 0.003) and increased more rapidly in BPA-4 than PL (P < 0.001). There were no significant condition × time interactions on glucose, insulin, and C-peptide. Significant condition main effects were observed for glucose such that BPA-50 was significantly lower than PL (P = 0.036) and nearly lower for BPA-4 vs PL (P = 0.056). Significant condition main effects were observed such that insulin in BPA-50 was lower than BPA-4 (P = 0.021), and C-peptide in BPA-50 was lower than BPA-4 (t18 = 3.95; Tukey-adjusted P = 0.003). Glucose, insulin, and C-peptide areas under the curve for the 3-hour profile were significantly lower in BPA-50 vs PL (P < 0.05).

CONCLUSION

Orally administered BPA protocol appeared feasible and has immediate effects on glucose, insulin, and C-peptide concentrations.

Predictors of urinary phthalate biomarker concentrations in postmenopausal women

BACKGROUND

Phthalates are ubiquitous endocrine disrupting chemicals present in a wide variety of consumer products. However, the personal characteristics associated with phthalate exposure are unclear.

OBJECTIVES

We sought to describe personal, behavioral, and reproductive characteristics associated with phthalate metabolite concentrations in an ongoing study nested within the Women's Health Initiative (WHI).

MATERIALS AND METHODS

We measured thirteen phthalate metabolites in two or three archived urine samples collected in 1993-2001 from each of 1257 WHI participants (2991 observations). We fit multivariable generalized estimating equation models to predict urinary biomarker concentrations from personal, behavioral, and reproductive characteristics.

RESULTS

Older age was predictive of lower concentrations of monobenzyl phthalate (MBzP), mono-carboxyoctyl phthalate (MCOP), mono-3-carboxypropyl phthalate (MCPP), and the sum of di-n-butyl phthalate metabolites (ΣDBP). Phthalate metabolite concentrations varied by race/region, with generally higher concentrations observed among non-Whites and women from the West region. Higher neighborhood socioeconomic status predicted lower MBzP concentrations, and higher education predicted lower monoethyl phthalate (MEP) and higher concentrations of the sum of metabolites of di-isobutyl phthalate (ΣDiBP). Overweight/obesity predicted higher MBzP, MCOP, monocarboxynonyl phthalate (MCNP), MCPP, and the sum of metabolites of di(2-ethylhexyl) phthalate (ΣDEHP) and lower MEP concentrations. Alcohol consumption predicted higher concentrations of MEP and ΣDBP, while current smokers had higher ΣDBP concentrations. Better diet quality as assessed by Healthy Eating Index 2005 scores predicted lower concentrations of MBzP, ΣDiBP, and ΣDEHP.

CONCLUSION

Factors predictive of lower biomarker concentrations included increased age and healthy behaviors (e.g. lower alcohol intake, lower body mass index, not smoking, higher quality diet, and moderate physical activity). Racial group (generally higher among non-Whites) and geographic regions (generally higher in Northeast and West compared to South regions) also were predictive of phthalate biomarker concentrations.

Exposure to Bisphenol a Substitutes and Gestational Diabetes Mellitus: A Prospective Cohort Study in China

Background: The association of bisphenol A (BPA) and gestational diabetes mellitus (GDM) has been investigated in only a small number of studies, and research on the associations between BPA substitutes and GDM is scarce. Objective: We aimed to investigate the associations of four bisphenols [bisphenol A (BPA), bisphenol S (BPS), bisphenol F (BPF), and bisphenol AF (BPAF)] levels in urine sample with the risk of gestational diabetes mellitus (GDM) and plasma glucose levels. Methods: A total of 1,841 pregnant women from a cohort study were recruited at their first prenatal examination between 2013 and 2015 in Wuhan, China. Concentrations of four bisphenols (BPA, BPS, BPF, BPAF) were measured in first-trimester urine samples using Ultra-high performance liquid chromatography system coupled to a Triple Quadrupole mass spectrometer (UHPLC-TQMS). An oral glucose tolerance test (OGTT) was performed at 24-28 gestational weeks and GDM was diagnosed post hoc using International Association of Diabetes and Pregnancy Study Groups criteria. We used multivariable logistic regression models to examine the associations of urinary bisphenols with the risk of GDM, and multiple linear regression models to determine the associations between bisphenols exposure and plasma glucose levels. Results: Urinary BPAF was associated with increased odds of GDM among women with normal pre-pregnancy BMI [adjusted odds ratio (aOR) = 1.70 (95% CI: 1.08, 2.67) for the highest group compared to the lowest group], and the association remained significant after additional adjustment for other bisphenols [aOR = 1.68 (95% CI: 1.03, 2.72)]. No significant associations were observed for other bisphenols and GDM. Consistent with the result of GDM, women in the highest BPAF category had a mean of 0.05 mmol/L (95% CI: 0.01, 0.09) higher fasting plasma glucose (FPG) levels than women in the lowest category. For BPA and plasma glucose, non-linear associations were observed between urinary BPA and FPG and the sum of the PG z-score among women who were overweight (p for non-linear association < 0.05). We also found that the per-unit increase in natural log transformed specific gravity adjusted BPS [ln (SG-adj BPS)] was associated with a 0.03 mmol/L (95% CI: 0.01, 0.04) increase in FPG levels and the associations might be modified by fetal sex (p for interaction < 0.05). Among women with female fetus, a per-unit increase in ln (SG-adj BPS) was associated with a 0.04 mmol/L (95% CI: 0.02, 0.06) increase in FPG, a 0.11 mmol/L (95% CI: 0.04, 0.17) increase in 1 h-PG and a 0.19 mmol/L (95% CI: 0.08, 0.30) increase in the sum of PG z-score. Conclusions: Our results provide evidence that BPAF and BPS might be potential risk factors of GDM, which require to be studied further.

Association of urinary concentrations of bisphenols with type 2 diabetes mellitus: A case-control study

Bisphenols, as synthetic chemicals, have been widely detected in environmental and human samples. Epidemiological studies have reported relationships between bisphenol A (BPA) and type 2 diabetes mellitus (T2DM), but results are inconsistent. Additionally, the associations between other bisphenols (i.e., the substitutes of BPA) with T2DM have been scarcely reported. A case-control study was conducted to examine the associations of urinary bisphenols with T2DM by investigating 8 bisphenols in urine samples of 251 T2DM cases and 251 controls and using different statistic models. Urinary bisphenol AF (BPAF) and bisphenol S (BPS) concentrations were significantly positively associated with T2DM in the log-transformed statistical models and adjusted odd ratios (ORs) were separately 4.95 [95% confidence interval (CI): 3.15, 7.79] and 1.73 (95% CI: 1.37, 2.18), which was consistent with the results in categorical models (OR = 2.03; 95% CI: 1.31, 3.15; p = 0.001 for BPAF; OR = 3.83; 95% CI: 2.37, 6.20; p < 0.001 for BPS). In addition, in the categorical models, elevated odds of T2DM were observed in the second BPA quartile (OR = 2.58; 95% CI: 1.38, 4.80) and the third quartile (OR = 1.89; 95% CI: 1.03, 3.46), but not in the fourth quartile, which reflected a nonlinear association between urinary BPA and T2DM. Similarly, only significant positive association with T2DM was found in the second quartile of the sum of bisphenols (OR = 2.07; 95% CI: 1.12, 3.82). In the sensitivity analyses, the associations of bisphenols with T2DM remained consistent except for BPAF in the categorical model. Our study suggested that several urinary bisphenols were positively associated with T2DM.

Estimating population exposure to phthalate esters in major Chinese cities through wastewater-based epidemiology

Phthalate esters (PAEs) are widely used in consumer and industrial products and may thus pose significant health risks. Urine analysis, which has usually been applied to assess the health risks of PAEs, has the drawback of small sample sizes and insufficient representativeness. Wastewater-based epidemiology (WBE) collects wastewater samples containing urine from the entire community and thus is more representative than urine samples. In this work, exposure levels and health risks of PAEs were estimated on a national scale for the first time through the WBE approach. Wastewater samples were collected from 54 wastewater treatment plants in 27 major cities that cover all of the geographic regions of China. The estimated ∑5PAEs exposure levels ranged from 290 μg/inh/d (Lhasa) to 3642 ± 467 μg/inh/d (Zhengzhou) with a mean level of 2184 ± 1173 μg/inh/d. Di-n-butyl phthalate accounted for the highest proportion (65%) in the total exposure level. The ∑5PAEs exposure levels in Southwest China were significantly lower than those in other regions due to the low production and consumption of plastics in the region. The health risks of PAEs were assessed by comparing the estimated daily exposure levels to the acceptable daily exposure levels. For adults, the hazard index that represents cumulative risk of PAEs was above or below 1 depending on a particular reference dose (total daily intake values or the reference dose for anti-androgenicity) that was used for risk calculation. In contrast, the hazard index was above 1 for a significant number of cities for children, regardless of which reference dose was used. The results indicate that health risks of PAE exposure in China cannot be overlooked. Children in China are under considerably greater risks than adults, which warrants further research or proper regulation of PAE use in China.

Bisphenol A exposure and type 2 diabetes mellitus risk: a meta-analysis

BACKGROUND

This meta-analytic study explored the relationship between the risk of type 2 diabetes mellitus (T2DM) and bisphenol A concentrations.

METHODS

The Embase and Medline (PubMed) databases were searched, using relevant keywords, for studies published between 1980 and 2018. A total of 16 studies, twelve cross-sectional, two case-control and one prospective, were included in the meta-analysis. The odds ratio (OR) and its 95% confidence interval (CI) were determined across the sixteen studies. The OR and its 95% CI of diabetes associated with bisphenol A were estimated using both fixed-effects and random-effects models.

RESULTS

A total of 41,320 subjects were included. Fourteen of the sixteen studies included in the analysis provided measurements of urine bisphenol A levels and two study provided serum bisphenol A levels. Bisphenol A concentrations in human bio-specimens showed positive associations with T2DM risk (OR 1.28, 95% CI 1.14, 1.44). A sensitivity analysis indicated that urine bisphenol A concentrations were positively associated with T2DM risk (OR 1.20, 95% CI 1.09, 1.31).

CONCLUSIONS

This meta-analysis indicated that Bisphenol A exposure is positively associated with T2DM risk in humans.

Effects of bisphenol A on metabolism and evidences of a mode of action mediated through endocrine disruption

Based on rodent studies after prenatal and/or perinatal or adult exposure, there is now evidence that BPA may increase metabolic disturbances eventually leading to type-2 diabetes development via an ED MoA. In particular, BPA has been shown to alter insulin synthesis and/or release by pancreatic β-cells, and insulin signaling within insulin-sensitive organs (i.e., liver, muscle, adipose tissues). This resulted in variations in the expression of specific hepatic or adipose tissue markers, which are indicative of a state of insulin resistance. These effects are considered by experts to be hallmarks of adverse hormonal effects, each leading to insulin resistance within the different insulin-sensitive tissues. Although epidemiological studies are inconclusive, these effects are considered relevant for humans, because similarities exist in homeostatic regulation of insulin production and sensitivity between rodents and humans and because evidence was also shown through in vitro experimental data using human cells or tissues.

Mitochondria as target of endocrine-disrupting chemicals: implications for type 2 diabetes

Type 2 diabetes is a chronic, heterogeneous syndrome characterized by insulin resistance and pancreatic β-cell dysfunction or death. Among several environmental factors contributing to type 2 diabetes development, endocrine-disrupting chemicals (EDCs) have been receiving special attention. These chemicals include a wide variety of pollutants, from components of plastic to pesticides, with the ability to modulate endocrine system function. EDCs can affect multiple cellular processes, including some related to energy production and utilization, leading to alterations in energy homeostasis. Mitochondria are primarily implicated in cellular energy conversion, although they also participate in other processes, such as hormone secretion and apoptosis. In fact, mitochondrial dysfunction due to reduced oxidative capacity, impaired lipid oxidation and increased oxidative stress has been linked to insulin resistance and type 2 diabetes. Herein, we review the main mechanisms whereby metabolism-disrupting chemical (MDC), a subclass of EDCs that disturbs energy homeostasis, cause mitochondrial dysfunction, thus contributing to the establishment of insulin resistance and type 2 diabetes. We conclude that MDC-induced mitochondrial dysfunction, which is mainly characterized by perturbations in mitochondrial bioenergetics, biogenesis and dynamics, excessive reactive oxygen species production and activation of the mitochondrial pathway of apoptosis, seems to be a relevant mechanism linking MDCs to type 2 diabetes development.

Transgenerational effects of maternal bisphenol: a exposure on offspring metabolic health

Exposure to the endocrine disruptor bisphenol A (BPA) is ubiquitous and associated with health abnormalities that persist in subsequent generations. However, transgenerational effects of BPA on metabolic health are not widely studied. In a maternal C57BL/6J mice (F0) exposure model using BPA doses that are relevant to human exposure levels (10 μg/kg/day, LowerB; 10 mg/kg/day, UpperB), we showed male- and dose-specific effects on pancreatic islets of the first (F1) and second generation (F2) offspring relative to controls (7% corn oil diet; control). In this study, we determined the transgenerational effects (F3) of BPA on metabolic health and pancreatic islets in our model. Adult F3 LowerB and UpperB male offspring had increased body weight relative to Controls, however glucose tolerance was similar in the three groups. F3 LowerB, but not UpperB, males had reduced β-cell mass and smaller islets which was associated with increased glucose-stimulated insulin secretion. Similar to F1 and F2 BPA male offspring, staining for markers of T-cells and macrophages (CD3 and F4/80) was increased in pancreas of F3 LowerB and UpperB male offspring, which was associated with changes in cytokine levels. In contrast to F3 BPA males, LowerB and UpperB female offspring had comparable body weight, glucose tolerance and insulin secretion as Controls. Thus, maternal BPA exposure resulted in fewer metabolic defects in F3 than F1 and F2 offspring, and these were sex- and dose-specific.

Urinary concentrations of environmental phenols and their association with type 2 diabetes in a population in Jeddah, Saudi Arabia

A few epidemiologic studies suggest that exposure to bisphenol A (BPA) is associated with type 2 diabetes mellitus (T2DM). However, little is known about association between other phenolic endocrine disrupting chemicals (EDCs) and T2DM. In this case-control study, we measured urinary concentrations of 23 phenolic EDCs in 101 individuals from Jeddah, Saudi Arabia, to examine the association of parabens, antimicrobials, bisphenols, benzophenones and bisphenol A diglycidyl ethers with T2DM. Urine samples were collected from 54 T2DM cases and 47 non-diabetic individuals (controls), aged 28-68 years old, during 2015-2016. Unconditional logistic regression was performed to estimate odd ratios (ORs) for the association between diabetes and EDC exposures after adjusting for confounders including age, gender, nationality, smoking status and occupation. Age from 40 to 59 years (OR 5.56, 95% CI 2.20-14.0) and smoking status (OR 2.92, 95% CI 1.25-6.79) showed significant positive associations with T2DM. After adjusting for potential confounders, we found that T2DM cases had high urinary levels of parabens (i.e., methyl- (MeP), ethyl- (EtP), propyl- (PrP) and 4-hydroxy benzoic acid (4-HB)), bisphenols (i.e., bisphenols A (BPA) and F (BPF)), and benzophenone (i.e., 4-hydroxybenzophenone (4-OH-BP)) relative to the controls. Individuals in the 4th quartile for urinary concentrations of MeP, EtP, PrP, 4-HB and BPF and in the 3rd quartile for BPA and 4-OH-BP showed over a 6-fold increase in the odds of having diabetes compared with those in the first quartile. Overall, our study shows that urinary levels of multiple phenolic EDCs were associated with increased risk for diabetes. Further prospective studies are required to verify these associations.

Elevated Concentrations of Bisphenols, Benzophenones, and Antimicrobials in Pantyhose Collected from Six Countries

Pantyhose, a skin-tight item of clothing made of synthetic fibers and worn by women in many countries, is a source of exposure to several endocrine-disrupting chemicals. Little is known regarding the occurrence of and dermal exposure to chemicals present in pantyhose. In this study, concentrations and profiles of 23 endocrine-disrupting chemicals, including bisphenols, benzophenones, chlorophenols, parabens, and triclocarban (TCC), were determined in 74 pantyhose samples collected from 6 countries. Pantyhose samples were analyzed by two extraction methods: complete dissolution and ultrasonic extraction. Dissolution of the fabric in 1,1,1,3,3,3-hexafluoro-2-propanol/chloroform yielded concentrations of several target chemicals that were up to 286 times higher than in the ultrasonic extraction. Bisphenol S (BPS) and bisphenol A (BPA) were found in 100% and 96% of the samples at median concentrations of 1430 and 14.3 ng/g, respectively. Several brands of pantyhose contained BPS, bisphenol F (BPF), benzophenone-1 (BP-1), ethyl-paraben (EtP), and TCC at concentrations of milligrams per gram. Benzophenone-3 (BP-3), 4-hydroxy benzoic acid (4-HB), and methyl- (MeP) and propyl-parabens (PrP) were found in ≥85% of the samples at median concentrations on the order of several tens to hundreds of nanograms per gram of fabric. Pantyhose made in Japan and China with 21-50% Spandex contained the highest concentrations of BPS (2.2 mg/g), BP-1 (2.4 mg/g), and EtP (88 μg/g). Calculated dermal exposure doses to BPS, BP-1, and EtP by women via pantyhose were as high as 45 900, 50 600, and 1800 picograms per kilogram of body weight per day, respectively.

Urinary bisphenol-A levels in children with type 1 diabetes mellitus

BACKGROUND

Bisphenol-A (BPA) is one of the most abundantly produced chemicals globally. Concerns have been raised about BPA's possible role in the pathogenesis of type 1 diabetes mellitus (T1DM). The main aim of the current study was to evaluate the possible association between BPA exposure and T1DM. The second aim was to investigate children's possible BPA exposure routes in Turkey.

METHODS

A total of 100 children aged between 5 and 18 years including 50 children with T1DM and 50 healthy children were included. Urinary BPA levels of all children were measured using high-performance liquid chromatography. Mothers of children enrolled in the study were also requested to complete a survey that included questions on the sociodemographic characteristics, medical history and possible BPA exposure routes of their children.

RESULTS

In the T1DM group, urinary BPA levels were slightly higher compared to the control group, but this difference was not significant (p=0.510). However, there was an inverse relationship between current urinary BPA levels and birth weight. It was found that the use of plastic kettles and the consumption of dairy products in plastic boxes significantly increased the urinary BPA concentrations in all subjects.

CONCLUSIONS

Although there was no significant association between urinary BPA levels and T1DM, we found an inverse relationship between current urinary BPA levels and birth weight. This finding might be important for prenatal exposure, and further prospective research must be conducted. Also, the use of plastic kettles, which has not been mentioned much in the literature before, was found to be an important exposure route for BPA.

Sex differences, endogenous sex-hormone hormones, sex-hormone binding globulin, and exogenous disruptors in diabetes and related metabolic outcomes

In assessing clinical and pathophysiological development of type 2 diabetes (T2D), the critical role of the sex steroids axis is underappreciated, particularly concerning the sex-specific relationships with many relevant cardiometabolic outcomes. In this issue of the Journal of Diabetes, we provide a comprehensive overview of these significant associations of germline variants in the genes governing the sex steroid pathways, plasma levels of steroid hormones, and sex hormone-binding globulin (SHBG) with T2D risk that have been observed in many clinical and high-quality large prospective cohorts of men and women across ethnic populations. Together, this body of evidence indicates that sex steroids and SHBG should be routinely incorporated into clinical characterization of T2D patients, particularly in screening prediabetic patients, such as those with metabolic syndrome, using plasma levels of SHBG. Given that several germline mutations in the SHBG gene have also been directly related to both plasma concentrations of SHBG and clinical manifestation of T2D, targeting signals in the sex steroid axis, particularly SHBG, may have significant utility in the prediction and treatment of T2D. Further, many of the environmental endocrine disrupting chemicals may exert their potential adverse effects on cardiometabolic outcomes via either estrogenic or androgenic signaling pathways, highlighting the importance of using the sex steroids and SHBG as important biochemical markers in both clinical and population studies in studying sex-specific mechanisms in the pathogenesis of T2D and its complications, as well as the need to equitably allocate resources in studying both men and women.

The role of pollutants in type 2 diabetes mellitus (T2DM) and their prospective impact on phytomedicinal treatment strategies

Type 2 diabetes mellitus (T2DM) is the most common form of diabetes and it is characterized by high blood sugar and abnormal sera lipid levels. Although the specific reasons for the development of these abnormalities are still not well understood, traditionally, genetic and lifestyle behavior have been reported as the leading causes of this disease. In the last three decades, the number of diabetic patients has drastically increased worldwide, with current statistics suggesting the number is to double in the next two decades. To combat this incurable ailment, orthodox medicines, to which economically disadvantaged patients have minimal access to, have been used. Thus, a considerable amalgamation of medicinal plants has recently been proven to possess therapeutic capabilities to manage T2DM, and this has prompted studies primarily focusing on the healing aspect of these plants, and ultimately, their commercialization. Hence, this review aims to highlight the potential threat of pollutants, i.e., polyfluoroalkyl compounds (PFCs), endocrine disrupting chemicals (EDCs) and heavy metals, to medicinal plants, and their prospective impact on the phytomedicinal therapy strategies for T2DM. It is further suggested that auxiliary research be undertaken to better comprehend the factors that influence the uptake of these compounds by these plants. This should include a comprehensive risk assessment of phytomedicinal products destined for the treatment of T2DM. Regulations that control the use of PFC-precursors in certain developing countries are also long overdue.

Serum Bisphenol A is an independent risk factor of hyperuricemia: A 6-year prospective study

OBJECTIVE

This study aims to evaluate whether serum Bisphenol A (BPA) is a risk factor for hyperuricemia.

METHODS

In this prospective study, a total of 482 participants without hyperuricemia were enrolled at baseline and followed up for 6 years. Clinical characteristics were recorded, and serum levels of uric acid and BPA were measured. Participants were stratified into tertiles according to low, median, and high baseline serum BPA levels. Regression models were used to analyze associations of serum BPA with the change in uric acid and the risk of developing hyperuricemia.

RESULTS

At baseline, serum concentrations of BPA was 0.51 (0.24-2.37) ng/mL. After 6 years of follow-up, the change in serum uric acid concentration from baseline to the 6-year mark was significantly higher in subjects with higher baseline BPA concentration (0.03 ± 0.19, 0.07 ± 0.21, and 0.11 ± 0.25mg/dL for low, median, and high tertiles, respectively, P = 0.006). When adjusted for potential confounders, such as age, renal function, and history of diabetes and hypertension, multivariable logistic analyses showed that subjects in the median or high baseline BPA tertiles exhibited a twofold higher risk of 6-year hyperuricemia incidence compared to subjects in the low baseline BPA tertile [odds ratio (OR) = 2.28 (95% CI: 1.05-4.95) for the median tertile; 2.42 (1.07-5.48) for the high tertile, P_{for Trend} = 0.043].

CONCLUSION

In conclusion, serum BPA is an independent risk factor for hyperuricemia.

Embryonic exposure to Mono(2-ethylhexyl) phthalate (MEHP) disrupts pancreatic organogenesis in zebrafish (Danio rerio)

Mono(2-ethylhexyl) phthalate (MEHP) is the bioactive metabolite of di(2-ethylhexyl) phthalate, a plasticizing agent and persistent environmental contaminant associated with obesity, developmental abnormalities, and oxidative stress. Nrf2 (Nfe2l2) is a transcription factor that regulates cytoprotective genes as part of the adaptive antioxidant response. We previously identified the pancreas as a sensitive target of oxidative stress during embryonic development. The goals of this study were to 1) characterize the effects of MEHP exposure on pancreatic development, and 2) determine whether oxidative stress contributes to MEHP embryotoxicity. Zebrafish (Danio rerio) embryos from AB wildtype and Tg(ins:GFP;nrf2a^fh318/fh318) were exposed to 0 or 200 μg/L MEHP at 3 h post fertilization (hpf) through 168 hpf to assess pancreatic organogenesis. MEHP exposure significantly decreased β-cell area at all timepoints (48, 72, 96, 168 hpf), but Nrf2a did not significantly protect against islet hypomorphism. Tg(gcga:GFP) embryos exposed to MEHP showed a decrease in α-cell area in the islet across the same timepoints. Tg(ptf1a:GFP) embryos were assessed at 80 and 168 hpf for exocrine pancreas length. MEHP exposure decreased growth of the exocrine pancreas. Expression of pancreas genes insa, sst2 and ptf1a was significantly reduced by MEHP exposure compared to controls. Glutathione (GSH) concentrations and redox potentials were quantified at 72 hpf by HPLC, but no significant changes were observed. However, expression of the GSH-related genes gstp1 and gsr were significantly altered by MEHP exposure. These data indicate that the developing pancreas is a sensitive target tissue of embryonic exposure to MEHP.

Serum Phthalate and Triclosan Levels Have Opposing Associations With Risk Factors for Gestational Diabetes Mellitus

Certain phthalates and bisphenol A (BPA) have been associated with insulin resistance and type 2 diabetes in non-pregnant adults, but studies of gestational diabetes mellitus (GDM) have reported conflicting results for phthalates and no associations with BPA. Our aim was to investigate the relationship between maternal serum levels of phthalate metabolites and phenols at 10-17 weeks of gestation and glucose homeostasis at 28 weeks of gestation. 232 women aged ≥16 years without type 1 or 2 diabetes with singleton male pregnancies were recruited from a single UK maternity centre between 2001 and 2009 as part of a prospective observational study (Cambridge Baby Growth Study). Serum levels of 16 phthalate metabolites and 9 phenols (including BPA) were measured using liquid chromatography/tandem mass spectrometry. Oral glucose tolerance tests were performed at 28 weeks. 47/232 (20.3%) women had GDM. First-trimester triclosan (TCS) was inversely associated with incident GDM (adjusted odds ratio per log increase in concentration 0.54, 95% confidence interval 0.34-0.86, p = 0.010). Amongst women without GDM, first-trimester mono-(2-ethylhexyl) phthalate and mono(carboxyisooctyl) phthalate levels were positively associated with 120-min plasma glucose (adjusted β 0.268 and 0.183, p = 0.0002 and 0.010, respectively) in mid-pregnancy. No other monotonic associations were detected between phthalate or phenol levels and fasting or stimulated plasma glucose, β-cell function, insulin resistance, or 60-min disposition index. Our results support a glycaemia-raising effect of phthalates during pregnancy, consistent with findings in non-pregnant populations and suggest a possible protective effect of exposure to TCS against GDM.

Disparities in Environmental Exposures to Endocrine-Disrupting Chemicals and Diabetes Risk in Vulnerable Populations

Burgeoning epidemiological, animal, and cellular data link environmental endocrine-disrupting chemicals (EDCs) to metabolic dysfunction. Disproportionate exposure to diabetes-associated EDCs may be an underappreciated contributor to disparities in metabolic disease risk. The burden of diabetes is not uniformly borne by American society; rather, this disease disproportionately affects certain populations, including African Americans, Latinos, and low-income individuals. The purpose of this study was to review the evidence linking unequal exposures to EDCs with racial, ethnic, and socioeconomic diabetes disparities in the U.S.; discuss social forces promoting these disparities; and explore potential interventions. Articles examining the links between chemical exposures and metabolic disease were extracted from the U.S. National Library of Medicine for the period of 1966 to 3 December 2016. EDCs associated with diabetes in the literature were then searched for evidence of racial, ethnic, and socioeconomic exposure disparities. Among Latinos, African Americans, and low-income individuals, numerous studies have reported significantly higher exposures to diabetogenic EDCs, including polychlorinated biphenyls, organochlorine pesticides, multiple chemical constituents of air pollution, bisphenol A, and phthalates. This review reveals that unequal exposure to EDCs may be a novel contributor to diabetes disparities. Efforts to reduce the individual and societal burden of diabetes should include educating clinicians on environmental exposures that may increase disease risk, strategies to reduce those exposures, and social policies to address environmental inequality as a novel source of diabetes disparities.

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.

Exposure to phthalates in patients with diabetes and its association with oxidative stress, adiponectin, and inflammatory cytokines

Epidemiologic studies have revealed higher concentrations of the metabolites of phthalic acid esters (mPAEs) in patients with type 2 diabetes. On the other hand, oxidative stress, adiponectin, and inflammatory cytokines play important roles in the pathogenesis of diabetes and its complications. However, little information is known about the association between exposure to PAEs and these physiological parameters. Hence, paired urine and blood samples were collected from a total of 329 volunteers, and 11 main mPAEs and malondialdehyde (MDA), as a biomarker of oxidative stress, were measured in the urine samples. Serum adiponectin and tumor necrosis factor-α (TNF-α), a biomarker of inflammation, were also measured. Multivariable linear regression was used to assess the association between urinary mPAEs and these physiological parameters in the total subjects and subjects stratified by age, sex, and body mass index (BMI) to elucidate their possible interactions. All 11 mPAEs were detected in the urine with detection rates of 42.9%-100% and geometric means of 0.30-54.52ng/mL (0.44-79.93μg/g creatinine). The mPAEs were all positively associated with MDA levels. There were significant positive associations between monomethyl phthalate (mMP) and TNF-α, and inverse associations between mMP and adiponectin levels. In the stratified analysis, there were age-, sex-, and BMI-specific differences for these associations. The positive associations between mPAEs and MDA were insignificant in some subgroups, especially in the larger age group. However, in the larger BMI group, summed metabolites of di-(2-ethylhexyl) phthalate (∑DEHP) and mono(2-ethylhexyl) phthalate were positively associated with TNF-α, and the concentrations of ∑DEHP were negatively associated with adiponectin. Our findings suggested that PAE exposure is associated with oxidative stress, adiponectin, and inflammatory cytokines in diabetic patients; further studies on toxicology and a comparison with general population are needed.