Ambient Volatile Organic Compounds and Racial/Ethnic Disparities in Gestational Diabetes Mellitus: Are Asian/Pacific Islander Women at Greater Risk?

Microglia Mediate Metabolic Dysfunction From Common Air Pollutants Through NF-κB Signaling

The prevalence of type 2 diabetes (T2D) poses a significant health challenge, yet the contribution of air pollutants to T2D epidemics remains under-studied. Several studies demonstrated a correlation between exposure to volatile organic compounds (VOCs) in indoor/outdoor environments and T2D. Here, we conducted the first meta-analysis, establishing a robust association between exposure to benzene, a prevalent airborne VOC, and insulin resistance in humans across all ages. We used a controlled benzene exposure system, continuous glucose monitoring approach, and indirect calorimetry in mice, to investigate the underlying mechanisms. Following exposure, disruptions in energy homeostasis, accompanied by modifications in the hypothalamic transcriptome and alterations in insulin and immune signaling, were observed exclusively in males, leading to a surge in blood glucose levels. In agreement, RNA sequencing of microglia revealed increased expression of genes associated with immune response and NF-κB signaling. Selective ablation of IKKβ in immune cells (Cx3cr1GFPΔIKK) or exclusively in microglia (Tmem119ERΔIKK) in adult mice alleviated benzene-induced gliosis, restored energy homeostasis and hypothalamic gene expression, and protected against hyperglycemia. We conclude that the microglial NF-κB pathway plays a critical role in chemical-induced metabolic disturbances, revealing a vital pathophysiological mechanism linking exposure to airborne toxicants and the onset of metabolic diseases.

ARTICLE HIGHLIGHTS

Unraveling the enigma: chronic kidney disease of unknown etiology and its causative factors with a specific focus on dissolved organic compounds in groundwater-reviews and future prospects

Chronic kidney disease is globally recognized as a highly impactful non-communicable disease. The inability of early identification contributes to its high mortality rate and financial burden on affected individuals. Chronic kidney disease of uncertain etiology (CKDu) constitutes a significant global public health concern. This condition does not arise from traditional risk factors such as diabetes, hypertension, or glomerulonephritis. More than 150 articles were analysed to understand risk factors of CKDu. This study aimed to investigate the potential association between dissolved organic compounds, such as Polycyclic Aromatic Hydrocarbons and Humic Acid, and the incidence of CKDu. Through a comprehensive literature review, we identified CKDu clusters worldwide, including notable nephropathies, and explored their potential links with organic compounds. Our analysis revealed that organic compounds can leach from sediments and low-rank lignite deposits into groundwater, subsequently contaminating water supplies and food. These compounds have been implicated in the development of diabetes and increased heavy metal mobility, both of which are risk factors for kidney disease. Our findings suggest that exposure to organic compounds may contribute to the etiology of CKDu, underscoring the need for regular monitoring and establishment of baseline and threshold values in water and soil. We also emphasize the importance of analyzing organic compounds in groundwater in CKDu hotspots and establishing distinct registries for CKD and CKDu implementation.

Gestational Diabetes and Subsequent Metabolic Dysfunction: An National Health and Nutrition Examination Survey Analysis (2011-2018)

Background: Gestational diabetes mellitus (GDM) complicates ∼10% of pregnancies, with the highest rates among Asian women. Evidence suggests that GDM is associated with an increased risk for future chronic health conditions, yet data for Asian women are sparse. We explored the association between prior GDM and metabolic dysfunction with nationally representative data to obtain Asian-specific estimates. Methods: For this cross-sectional study, data were drawn from the National Health and Nutrition Examination Survey for 7195 women with a prior pregnancy. GDM (yes/no) was defined using the question "During pregnancy, were you ever told by a doctor or other health professional that you had diabetes, sugar diabetes, or gestational diabetes?." Current metabolic dysfunction (yes/no) was based on having at least one of four indicators: systolic blood pressure (SBP, ≥130 mmHg), waist circumference (≥88 cm), high-density lipoprotein (HDL) cholesterol (<50 mg/dL), and glycosylated hemoglobin (HbA1c) (≥6.5%). Logistic regression estimated odds ratios (ORs) and 95% confidence intervals (CIs) for the association between prior GDM and metabolic outcomes, overall and by race. Models included sampling weights and demographic and behavioral factors. Results: Overall, women with prior GDM had 46% greater odds of high waist circumference (OR: 1.5; 95% CI: 1.1-2.0) and 200% greater odds (OR: 3.0; 95% CI: 2.1-4.2) of high HbA1c. Prior GDM was not associated with high blood pressure or low HDL cholesterol. In race-specific analyses, prior GDM was associated with increased risk of elevated HbA1c among Asian (OR: 6.6; 95% CI: 2.5-17.2), Mexican American (OR: 3.0; 95% CI: 1.5-5.8), Black (OR: 3.0; 95% CI: 1.7-5.5), and White (OR: 2.6; 95% CI: 1.5-4.6) women. Prior GDM was associated with elevated SBP among Mexican American women and low HDL among Black women. Discussion: Prior GDM is associated with elevated HbA1c among all women, yet is a stronger predictor of elevated HbA1c among Asian women than other women. Race-specific associations between prior GDM and metabolic dysfunction were observed among Mexican American and Black women. Further research is warranted to understand the observed race/ethnic-specific associations.

The role of liver enzymes in the association between ozone exposure and diabetes risk: a cross-sectional study of Zhuang adults in China

Background: Growing evidence has demonstrated the role of ambient air pollutants in driving diabetes incidence. However, epidemiological evidence linking ozone (O3) exposure to diabetes risk has been scarcely studied in Zhuang adults in China. We aimed to investigate the associations of long-term exposure to O3 with diabetes prevalence and fasting plasma glucose (FPG) and estimate the mediating role of liver enzymes in Zhuang adults. Methods: We recruited 13 843 ethnic minority adults during 2018-2019 based on a cross-sectional study covering nine districts/counties in Guangxi. Generalized linear mixed models were implemented to estimate the relationships between O3 exposure and diabetes prevalence and FPG. Mediation effect models were constructed to investigate the roles of liver enzymes in the associations of O3 exposure with diabetes prevalence and FPG. Subgroup analyses were conducted to identify potential effect modifications. Results: Long-term exposure to O3 was positively associated with diabetes prevalence and FPG levels in Zhuang adults, with an excess risk of 7.32% (95% confidence interval [CI]: 2.56%, 12.30%) and an increase of 0.047 mmol L-1 (95% CI: 0.032, 0.063) for diabetes prevalence and FPG levels, respectively, for each interquartile range (IQR, 1.18 μg m-3) increment in O3 concentrations. Alanine aminotransferase (ALT) significantly mediated 8.10% and 29.89% of the associations of O3 with FPG and diabetes prevalence, respectively, and the corresponding mediation proportions of alkaline phosphatase (ALP) were 8.48% and 30.00%. Greater adverse effects were observed in females, obese subjects, people with a low education level, rural residents, non-clean fuel users, and people with a history of stroke and hypertension in the associations of O3 exposure with diabetes prevalence and/or FPG levels (all P values for interaction < 0.05). Conclusion: Long-term exposure to O3 is related to an increased risk of diabetes, which is partially mediated by liver enzymes in Chinese Zhuang adults. Promoting clean air policies and reducing exposure to environmental pollutants should be a priority for public health policies geared toward preventing diabetes.

Microglial NF-κB Signaling Deficiency Protects Against Metabolic Disruptions Caused by Volatile Organic Compound via Modulating the Hypothalamic Transcriptome

Prolonged exposure to benzene, a prevalent volatile organic compound (VOC), at concentrations found in smoke, triggers hyperglycemia, and inflammation in mice. Corroborating this with existing epidemiological data, we show a strong correlation between environmental benzene exposure and metabolic impairments in humans. To uncover the underlying mechanisms, we employed a controlled exposure system and continuous glucose monitoring (CGM), revealing rapid blood glucose surges and disturbances in energy homeostasis in mice. These effects were attributed to alterations in the hypothalamic transcriptome, specifically impacting insulin and immune response genes, leading to hypothalamic insulin resistance and neuroinflammation. Moreover, benzene exposure activated microglial transcription characterized by heightened expression of IKKβ/NF-κB-related genes. Remarkably, selective removal of IKKβ in immune cells or adult microglia in mice alleviated benzene-induced hypothalamic gliosis, and protected against hyperglycemia. In summary, our study uncovers a crucial pathophysiological mechanism, establishing a clear link between airborne toxicant exposure and the onset of metabolic diseases.

Methods in Public Health Environmental Justice Research: a Scoping Review from 2018 to 2021

PURPOSE OF REVIEW

The volume of public health environmental justice (EJ) research produced by academic institutions increased through 2022. However, the methods used for evaluating EJ in exposure science and epidemiologic studies have not been catalogued. Here, we completed a scoping review of EJ studies published in 19 environmental science and epidemiologic journals from 2018 to 2021 to summarize research types, frameworks, and methods.

RECENT FINDINGS

We identified 402 articles that included populations with health disparities as a part of EJ research question and met other inclusion criteria. Most studies (60%) evaluated EJ questions related to socioeconomic status (SES) or race/ethnicity. EJ studies took place in 69 countries, led by the US (n = 246 [61%]). Only 50% of studies explicitly described a theoretical EJ framework in the background, methods, or discussion and just 10% explicitly stated a framework in all three sections. Among exposure studies, the most common area-level exposure was air pollution (40%), whereas chemicals predominated personal exposure studies (35%). Overall, the most common method used for exposure-only EJ analyses was main effect regression modeling (50%); for epidemiologic studies the most common method was effect modification (58%), where an analysis evaluated a health disparity variable as an effect modifier. Based on the results of this scoping review, current methods in public health EJ studies could be bolstered by integrating expertise from other fields (e.g., sociology), conducting community-based participatory research and intervention studies, and using more rigorous, theory-based, and solution-oriented statistical research methods.

Prenatal benzene exposure in mice alters offspring hypothalamic development predisposing to metabolic disease in later life

Maternal exposure to environmental contaminants during pregnancy poses a significant threat to a developing fetus, as these substances can easily cross the placenta and disrupt the neurodevelopment of offspring. Specifically, the hypothalamus is essential in the regulation of metabolism, notably during critical windows of development. An abnormal hormonal and inflammatory milieu during development can trigger persistent changes in the function of hypothalamic circuits, leading to long-lasting effects on the body's energy homeostasis and metabolism. We recently demonstrated that gestational exposure to clinically relevant levels of benzene induces severe metabolic dysregulation in the offspring. Given the central role of the hypothalamus in metabolic control, we hypothesized that prenatal exposure to benzene impacts hypothalamic development, contributing to the adverse metabolic effects in the offspring. C57BL/6JB dams were exposed to benzene at 50 ppm in the inhalation chambers exclusively during pregnancy (from E0.5 to E19). Transcriptomic analysis of the exposed offspring at postnatal day 21 (P21) revealed hypothalamic changes in genes related to metabolic regulation, inflammation, and neurodevelopment exclusively in males. Moreover, the hypothalamus of prenatally benzene-exposed male offspring displayed alterations in orexigenic and anorexigenic projections, impairments in leptin signaling, and increased microgliosis. Additional exposure to benzene during lactation did not promote further microgliosis or astrogliosis in the offspring, while the high-fat diet (HFD) challenge in adulthood exacerbated glucose metabolism and hypothalamic inflammation in benzene-exposed offspring of both sexes. These findings reveal the persistent adverse effects of prenatal benzene exposure on hypothalamic circuits and neuroinflammation, predisposing the offspring to long-lasting metabolic health conditions.

Urinary metabolites of multiple volatile organic compounds, oxidative stress biomarkers, and gestational diabetes mellitus: Association analyses

Volatile organic compounds are ubiquitous in the environment, which may cause various adverse health effects. The objectives of this study were to investigate associations of single and mixture of urinary metabolites of volatile organic compounds (mVOCs) with gestational diabetes mellitus (GDM) risk, and examine the possible role of oxidative stress in the associations. This nested case-control study included 454 GDM cases and 454 healthy controls matched by maternal age and infant sex. Urinary concentrations of twenty-one mVOCs and three oxidative stress biomarkers (including 8-OHdG, 8-OHG, and HNEMA), in early pregnancy were measured. Analyses using logistic regression model showed that an interquartile range increase in urinary concentrations of six individual mVOCs (ATCA, BPMA, CEMA, 3HPMA, MU, and TGA) were significantly associated with increased odds of GDM by 19-27%. Weighted quantile sum regression analyses showed that in each quartile increment of the mixture of mVOCs, the odds of GDM increased by 39% (95% CI: 16%, 67%), with 2-aminothiazoline-4-carboxylic acid weighted the most in the associations (weight: 25%). Furthermore, significant associations of the oxidative stress biomarkers with both GDM and certain mVOCs were observed. These results suggested that certain urinary mVOCs (correspondingly, the parent VOCs such as 1-bromopropane, cyanide, and benzene should be concerned as priority ones for regulation and policy making) in early pregnancy were significantly associated with elevated GDM incidence, and the associations were potentially related with oxidative stress biomarkers.

Associations between residential volatile organic compound exposures and liver injury markers: The role of biological sex and race

While occupational exposures to volatile organic compounds (VOCs) have been linked to steatohepatitis and liver cancer in industrial workers, recent findings have also positively correlated low-dose, residential VOC exposures with liver injury markers. VOC sources are numerous; factors including biological make up (sex), socio-cultural constructs (gender, race) and lifestyle (smoking) can influence both VOC exposure levels and disease outcomes. Therefore, the current study's objective is to investigate how sex and race influence associations between residential VOC exposures and liver injury markers particularly in smokers vs. nonsmokers. Subjects (n = 663) were recruited from residential neighborhoods; informed consent was obtained. Exposure biomarkers included 16 urinary VOC metabolites. Serological disease biomarkers included liver enzymes, direct bilirubin, and hepatocyte death markers (cytokeratin K18). Pearson correlations and generalized linear models were conducted. Models were adjusted for common liver-related confounders and interaction terms. The study population constituted approximately 60% females (n = 401) and 40% males (n = 262), and a higher percent of males were smokers and/or frequent drinkers. Both sexes had a higher percent of White (75% females, 82% males) vs. Black individuals. Positive associations were identified for metabolites of acrolein, acrylamide, acrylonitrile, butadiene, crotonaldehyde, and styrene with alkaline phosphatase (ALP), a biomarker for cholestatic injury; and for the benzene metabolite with bilirubin; only in females. These associations were retained in female smokers. Similar associations were also observed between these metabolites and ALP only in White individuals (n = 514). In Black individuals (n = 114), the styrene metabolite was positively associated with aspartate transaminase. Interaction models indicated that positive associations for acrylamide/crotonaldehyde metabolites with ALP in females were dose-dependent. Most VOC associations with K18 markers were negative in this residential population. Overall, the findings demonstrated that biological sex, race, and smoking status influence VOC effects on liver injury and underscored the role of biological-social-lifestyle factor(s) interactions when addressing air pollution-related health disparities.

Prenatal benzene exposure alters offspring hypothalamic development predisposing to metabolic disease in later life

The hypothalamus is essential in the regulation of metabolism, notably during critical windows of development. An abnormal hormonal and inflammatory milieu during development can trigger persistent changes in the function of hypothalamic circuits, leading to long-lasting effects on the body’s energy homeostasis and metabolism. We recently demonstrated that gestational exposure to benzene at smoking levels induces severe metabolic dysregulation in the offspring. Given the central role of the hypothalamus in metabolic control, we hypothesized that prenatal exposure to benzene impacts hypothalamic development, contributing to the adverse metabolic effects in the offspring. C57BL/6JB dams were exposed to benzene in the inhalation chambers exclusively during pregnancy (from E0.5 to E19). The transcriptome analysis of the offspring hypothalamus at postnatal day 21 (P21) revealed changes in genes related to metabolic regulation, inflammation, and neurodevelopment exclusively in benzene-exposed male offspring. Moreover, the hypothalamus of prenatally benzene-exposed male offspring displayed alterations in orexigenic and anorexigenic projections, impairments in leptin signaling, and increased microgliosis. Additional exposure to benzene during lactation did not promote further microgliosis or astrogliosis in the offspring, while the high-fat diet (HFD) challenge in adulthood exacerbated glucose metabolism and hypothalamic inflammation in benzene-exposed offspring of both sexes. These findings reveal the persistent impact of prenatal benzene exposure on hypothalamic circuits and neuroinflammation, predisposing the offspring to long-lasting metabolic health conditions.

Effect of airflow pattern and distance on removal of particulate matters and volatile organic compounds from cigarette smoke using Sansevieria trifasciata botanical biofilter

Botanical biofilters can effectively remove indoor air pollution. However, to apply botanical biofilters in situ, the distance of botanical biofilter to the pollutants and airflow pattern can be important factors impacting efficiency. This study examined the removal efficiency of particulate matters (PMs) and volatile organic compounds (VOCs) from cigarette smoke, such as formaldehyde and acetone, at various distances (100 cm, 175 cm, 240 cm, and 315 cm) using a Sansevieria trifasciata botanical biofilter. The botanical biofilter was placed inside a testing room (24 m³) and exposed to cigarette smoke. The pollutants removal efficiency was evaluated for six cycles (24 h/cycle) and one cycle as a recovery period where botanical biofilter was placed under normal conditions for 30 days. Results showed that the botanical biofilter could remove 140-250 μg m^-3, 147-257 μg m^-3, 212-455 μg m^-3 for PM₁, PM_2.5, and PM₁₀, respectively, at 8 h. Total VOCs, formaldehyde, and acetone removal were 40%-65%, 46%-69%, and 31%-61% at 24 h. PMs and VOCs removal efficiency can be affected by both distance and pattern of airflow in the testing room. The highest PM₁ and PM_2.5 elimination appeared at 240 cm and 315 cm, while VOCs removal was high at 100 cm. Botanical biofilter creates airflow vortices around 100 cm, indicating low removal of PMs. This is the first study that demonstrated the effect of airflow patterns on different pollutants removal efficiency.

A Scoping Review on Gestational Diabetes in Hawai'i: A "Window of Opportunity" to Address Intergenerational Risk for Type 2 Diabetes Mellitus

The health of women over the entire span of their reproductive years is crucial - beginning in adolescence and extending through the postpartum period. This paper provides a scoping review of the relevant literature on risk factors for gestational diabetes mellitus (GDM) and progression from GDM to type 2 diabetes mellitus (T2DM), particularly among women of Native Hawaiian and Pacific Islander (NHPI) and Asian racial/ethnic backgrounds in Hawai'i, using the PubMed database (July 2010 to July 2020). NHPI and Asian populations have a greater likelihood of developing GDM compared to their White counterparts. Risk factors such as advanced maternal age, high maternal body mass index, and lack of education about GDM have varying levels of impact on GDM diagnosis between ethnic populations. Mothers who have a history of GDM are also at higher risk of developing T2DM. Common risk factors include greater increase in postpartum body mass index and use of diabetes medications during pregnancy. However, few studies investigate the progression from GDM to T2DM in Hawai'i's Asian and NHPI populations, and no studies present upstream preconception care programs to prevent an initial GDM diagnosis among Hawai'i's women. Thus, updated reports are necessary for optimal early interventions to prevent the onset of GDM and break the intergenerational cycle of increased susceptibility to T2DM and GDM in both mother and child. Further attention to the development of culturally sensitive interventions may reduce disparities in GDM and improve the health for all affected by this condition.

Sex Difference and Benzene Exposure: Does It Matter?

Sex-related biological differences might lead to different effects in women and men when they are exposed to risk factors. A scoping review was carried out to understand if sex could be a discriminant in health outcomes due to benzene. Studies on both animals and humans were collected. In vivo surveys, focusing on genotoxicity, hematotoxicity and effects on metabolism suggested a higher involvement of male animals (mice or rats) in adverse health effects. Conversely, the studies on humans, focused on the alteration of blood parameters, myeloid leukemia incidence and biomarker rates, highlighted that, overall, women had significantly higher risk for blood system effects and a metabolization of benzene 23-26% higher than men, considering a similar exposure situation. This opposite trend highlights that the extrapolation of in vivo findings to human risk assessment should be taken with caution. However, it is clear that sex is a physiological parameter to consider in benzene exposure and its health effects. The topic of sex difference linked to benzene in human exposure needs further research, with more numerous samples, to obtain a higher strength of data and more indicative findings. Sex factor, and gender, could have significant impacts on occupational exposures and their health effects, even if there are still uncertainties and gaps that need to be filled.

Association between high-risk pregnancy and environmental contaminants in the Metropolitan Region of Baixada Santista, Brazil

The Metropolitan Region of Baixada Santista (MRBS) is a highly contaminated area. High-risk pregnancy is one factor that leads to a higher chance of both morbidity and mortality of the mother-fetus binomial. The purpose of this study is to analyze the association between exposure to environmental contaminants and high-risk pregnancy. Case-control study, using a probabilistic and random sample composed of 201 high-risk pregnant women (cases) and 201 no high-risk pregnant women (control) followed up during prenatal care at a Public Hospital. The instrument used was a self-administered questionnaire. Contaminated areas data were obtained from the Environmental Company of the São Paulo State. The participants were georeferenced by their place of residence. Descriptive analysis, Chi-square test, and univariate and multiple logistic regression analysis were performed. The multiple logistic regression model demonstrated that living in a contaminated area (OR = 1.565; 95%CI: 1.033; 2.370), preterm delivery in the current pregnancy (OR = 1.989; 95%CI: 1.239; 3.194), and more than 35 years old (OR = 2.822; 95%CI: 1.692; 4.706) are factors jointly related to high-risk pregnancy. Environmental contaminants play an important role in high-risk pregnancy, and mitigating measures are needed to improve the environment and reduce high-risk pregnancy.

Associations of propylene oxide exposure with fasting plasma glucose and diabetes: Roles of oxidative DNA damage and lipid peroxidation

Whether propylene oxide (PO) exposure is associated with hyperglycemia were rarely explored. We aimed to determine the relationship between PO exposure and glucose metabolism, and potential role of oxidative stress. Among 3294 Chinese urban adults, urinary PO metabolite (N-Acetyl-S-(2-hydroxypropyl)-L-cysteine, 2HPMA), biomarkers of oxidative DNA damage (8-oxo-7,8-dihydro-20-deoxyguanosine, 8-OHdG) and lipid peroxidation (8-isoprostane, 8-iso-PGF_2α) in urine were determined. The associations of 2HPMA with 8-OHdG, 8-iso-PGF_2α, fasting plasma glucose (FPG), and risk of diabetes were explored. The roles of 8-OHdG and 8-iso-PGF_2α on association of 2HPMA with FPG and risk of diabetes were detected. After adjusted for potential confounders, each 1-unit increase in log-transformed concentration of 2HPMA was associated with a 0.15-mmol/L increase in FPG level, and the adjusted OR (95% CI) of diabetes by the associations of log-transformed urinary 2HPMA concentrations was 1.47 (95% CI: 1.03-2.11). Combination effects of 2HPMA with 8-OHdG or 8-iso-PGF_2α on risk of diabetes were detected, and elevated 8-iso-PGF_2α significantly mediated 34.5% of the urinary 2HPMA-associated FPG elevation. PO exposure was positively associated with FPG levels and risk of diabetes. PO exposure combined with DNA oxidative damage or lipid peroxidation may increase the risk of diabetes, and lipid peroxidation may partially mediate the PO exposure-induced FPG elevation.

Joint effects of ethnic enclave residence and ambient volatile organic compounds exposure on risk of gestational diabetes mellitus among Asian/Pacific Islander women in the United States

BACKGROUND

Asian/Pacific Islander (API) communities in the United States often reside in metropolitan areas with distinct social and environmental attributes. Residence in an ethnic enclave, a socially distinct area, is associated with lower gestational diabetes mellitus (GDM) risk, yet exposure to high levels of air pollution, including volatile organic compounds (VOCS), is associated with increased GDM risk. We examined the joint effects of ethnic enclaves and VOCs to better understand GDM risk among API women, the group with the highest prevalence of GDM.

METHODS

We examined 9069 API births in the Consortium on Safe Labor (19 hospitals, 2002-2008). API ethnic enclaves were defined as areas ≥66th percentile for percent API residents, dissimilarity (geographic dispersal of API and White residents), and isolation (degree that API individuals interact with another API individual). High levels of 14 volatile organic compounds (VOC) were defined as ≥75th percentile. Four joint categories were created for each VOC: Low VOC/Enclave (reference group), Low VOC/No Enclave, High VOC/Enclave, High VOC/No Enclave. GDM was reported in medical records. Hierarchical logistic regression estimated odds ratios (OR) and 95% confidence intervals (95%CI) between joint exposures and GDM, adjusted for maternal factors and area-level poverty. Risk was estimated for 3-months preconception and first trimester exposures.

RESULTS

Enclave residence was associated with lower GDM risk regardless of VOC exposure. Preconception benzene exposure was associated with increased risk when women resided outside enclaves [High VOC/No Enclave (OR:3.45, 95%CI:1.77,6.72)], and the effect was somewhat mitigated within enclaves, [High VOC/Enclave (OR:2.07, 95%:1.09,3.94)]. Risks were similar for 12 of 14 VOCs during preconception and 10 of 14 during the first trimester.

CONCLUSIONS

API residence in non-enclave areas is associated with higher GDM risk, regardless of VOC level. Ethnic enclave residence may mitigate effects of VOC exposure, perhaps due to lower stress levels. The potential benefit of ethnic enclaves warrants further study.

In Utero Maternal Benzene Exposure Predisposes to the Metabolic Imbalance in the Offspring

Environmental chemicals play a significant role in the development of metabolic disorders, especially when exposure occurs early in life. We have recently demonstrated that benzene exposure, at concentrations relevant to cigarette smoke, induces a severe metabolic imbalance in a sex-specific manner affecting male but not female mice. However, the roles of benzene in the development of aberrant metabolic outcomes following gestational exposure, remain largely unexplored. In this study, we exposed pregnant C57BL/6JB dams to benzene at 50 ppm or filtered air for 6 h/day from gestational day 0.5 (GD0.5) through GD21 and studied male and female offspring metabolic phenotypes in their adult life. While no changes in body weight or body composition were observed between groups, 4-month-old male and female offspring exhibited reduced parameters of energy homeostasis (VO2, VCO2, and heat production). However, only male offspring from benzene-exposed dams were glucose intolerant and insulin resistant at this age. By 6 months of age, both male and female offspring exhibited marked glucose intolerance however, only male offspring developed severe insulin resistance. This effect was accompanied by elevated insulin secretion and increased beta-cell mass only in male offspring. In support, Homeostatic Model Assessment for Insulin Resistance, the index of insulin resistance was elevated only in male but not in female offspring. Regardless, both male and female offspring exhibited a considerable increase in hepatic gene expression associated with inflammation and endoplasmic reticulum stress. Thus, gestational benzene exposure can predispose offspring to increased susceptibility to the metabolic imbalance in adulthood with differential sensitivity between sexes.

Use of trajectory models to track air pollution from source to exposure: A methodological approach for identifying communities at risk

OBJECTIVE

Ongoing environmental changes increasingly require public health nurses to understand how environmental factors impact the health of populations. One approach to researching these impacts is incorporating environmental research methods to determine associations between harmful exposures and health. We use the Salton Sea in Southern California as a demonstration of how environmental exposure can be examined using air parcel trajectory analysis.

DESIGN

We demonstrate a methodology for public health nurses to better understand and apply data from the Hybrid Single-Particle Lagrangian Integrated Trajectory meteorological model to estimate the effect of airborne particulate matter from a single source.

MEASUREMENTS

We explain a method for tracking air parcel trajectories to populations: selection of meterological data to identify air parcels, geographic identification of population centers, generation of trajectories, classification of trajectory dispersions, adjusting for atmospheric stability, and merging environmental variables with health data.

CONCLUSIONS

Climate change-related environmental events are expected to become more commonplace and disproportionately affect those populations impacted by health disparities. Public health nurses can identify communities at risk so that public health nursing researchers can use these techniques in collaboration with environmental science to robustly examine health effects of proximal air pollution sources for communities at risk.

A Systematic Review of Racial and Ethnic Disparities in Maternal Health Outcomes among Asians/Pacific Islanders

Efforts to improve women's health and to reduce maternal mortality worldwide have led to a notable reduction in the global maternal mortality ratio (MMR) over the past two decades. However, it is clear that maternal health outcomes are not equitable, especially when analyzing the scope of maternal health disparities across "developed" and "underdeveloped" nations. This study evaluates recent MMR scholarship with a particular focus on the racial and ethnic divisions that impact on maternal health outcomes. The study contributes to MMR research by analyzing the racial and ethnic disparities that exist in the US, especially among Asian and Pacific Islander (API) subgroups. The study applies exclusionary criteria to 710 articles and subsequently identified various maternal health issues that disproportionately affect API women living in the US. In applying PRISMA review guidelines, the study produced 22 peer-reviewed articles that met inclusionary and exclusionary criteria for this review. The data analysis identified several maternal health foci: obstetric outcomes, environmental exposure, obstetric care and quality measures, and pregnancy-related measures. Only eight of the 22 reviewed studies disaggregated API populations by focusing on specific subgroups of APIs, which signals a need to reconceptualize marginalized API communities' inclusion in health care systems, to promote their equitable access to care, and to dissolve health disparities among racial and ethnic divides. Several short- and long-term initiatives are recommended to develop and implement targeted health interventions for API groups, and thus provide the groundwork for future empirically driven research among specific API subgroups in the US.

Climate factors and gestational diabetes mellitus risk - a systematic review

BACKGROUND

Current and projected increases in global temperatures and extreme climate events have led to heightened interest in the impact of climate factors (i.e. ambient temperature, season/seasonality, and humidity) on human health. There is growing evidence that climate factors may impact metabolic function, including insulin sensitivity. Gestational diabetes mellitus (GDM) is a common pregnancy complication, with an estimated global prevalence of up to 14%. While lifestyle and genetic risk factors for GDM are well established, environmental factors may also contribute to GDM risk. Previous reviews have summarized the growing evidence of environmental risk factors for GDM including endocrine disrupting chemicals and ambient air pollution. However, studies of the effects of climate factors on GDM risk have not been systematically evaluated. Therefore, we conducted a systematic review to summarize and evaluate the current literature on the associations of climate factors with GDM risk.

METHODS

We conducted systematic searches in PubMed and EMBASE databases for original research articles on associations of climate factors (i.e. ambient temperature, season/seasonality, and humidity) with GDM and/or related glycemic outcomes for all publication dates through September 20th, 2020.

RESULTS

Our search identified 16 articles on the associations of ambient temperature and/or season with GDM and maternal glycemic outcomes during pregnancy, which were included in this review. Despite inconsistencies in exposure and outcome assessment, we found consistent evidence of a seasonal effect on GDM risk, with higher prevalence of GDM and higher pregnancy glucose levels in summer months. We found suggestive evidence of an association between higher ambient temperature and elevated glucose levels from GDM screening tests.

CONCLUSION

Climate factors may be associated with GDM risk. However, further research is needed to evaluate these associations and to elucidate the specific mechanisms involved.

Ambient air pollution exposure associated with glucose homeostasis during pregnancy and gestational diabetes mellitus

BACKGROUND

To investigate the effects of air pollution exposure during pregnancy on the indicators of glucose homeostasis and gestational diabetes mellitus (GDM).

METHODS

We conducted a birth cohort study in Foshan, China during 2015-2019. Oral glucose tolerance test (OGTT) was administered to each participant during pregnancy. GDM was defined according to the International Association of Diabetes and Pregnancy Study Groups criteria (IADPSG). Air pollutant (fine particulate matter (PM_2.5), particulate matter with an aerodynamic diameter of 10 μm or less (PM₁₀), sulfate dioxide (SO₂), nitrogen dioxide (NO₂) and ozone (O₃)) concentrations from the air monitoring stations in Foshan were used to estimate individual air pollutant exposure during the first two trimesters. Linear and logistic regression models were employed to estimate the associations between air pollution exposure during the first two trimesters and OGTT glucose levels and GDM.

RESULTS

Of 12,842 pregnant women, 3055 (23.8%) had GDM. A 10 μg/m³ increase in PM_2.5, PM₁₀ and SO₂ during trimester 1, trimester 2 and two trimesters were associated with 0.07 mmol/L to 0.29 mmol/L increment in OGTT-fasting glucose levels in single-pollutant model. A 10 μg/m³ increase in NO₂ and O₃ during two trimesters were associated with 0.15 mmol/L and 0.12 mmol/L decrease in OGTT-fasting glucose in single-pollutant model. However, no significant or weaker effects of O₃ during two trimesters on OGTT-fasting glucose were observed in two-pollutant models. Moreover, exposure to PM_2.5, PM₁₀ and SO₂ were associated with increased risk of GDM in both single- and two-pollutant models.

CONCLUSIONS

Our study suggests PM_2.5, PM₁₀ and SO₂ exposure during the first two trimesters might increase the risk of GDM.

Acarbose protects from central and peripheral metabolic imbalance induced by benzene exposure

Benzene is a well-known human carcinogen that is one of the major components of air pollution. Sources of benzene in ambient air include cigarette smoke, e-cigarettes vaping, and evaporation of benzene containing petrol processes. While the carcinogenic effects of benzene exposure have been well studied, less is known about the metabolic effects of benzene exposure. We show that chronic exposure to benzene at low levels induces a severe metabolic imbalance in a sex-specific manner, and is associated with hypothalamic inflammation and endoplasmic reticulum (ER) stress. Benzene exposure rapidly activates hypothalamic ER stress and neuroinflammatory responses in male mice, while pharmacological inhibition of ER stress response by inhibiting IRE1α-XBP1 pathway significantly alleviates benzene-induced glial inflammatory responses. Additionally, feeding mice with Acarbose, a clinically available anti-diabetes drug, protected against benzene induced central and peripheral metabolic imbalance. Acarbose imitates the slowing of dietary carbohydrate digestion, suggesting that choosing a diet with a low glycemic index might be a potential strategy for reducing the negative metabolic effect of chronic exposure to benzene for smokers or people living/working in urban environments with high concentrations of exposure to automobile exhausts.

Associations of Per- and Polyfluoroalkyl Substances (PFAS) With Glucose Tolerance During Pregnancy in Project Viva

CONTEXT

Per- and polyfluoroalkyl substances (PFAS) exposure may alter glucose homeostasis. Research on PFAS exposure and glucose tolerance during pregnancy is limited.

OBJECTIVE

The objective of this work is to estimate associations between first-trimester plasma PFAS concentrations and glucose tolerance assessed in late second pregnancy trimester.

DESIGN, SETTING, PARTICIPANTS, AND MAIN OUTCOME MEASURES

Pregnant women (n = 1540) enrolled in Project Viva in 1999 to 2002 provided first-trimester plasma samples analyzed for 8 PFAS. At approximately 28 weeks' gestation, women completed 1-hour nonfasting, 50-g oral glucose challenge tests (GCTs); if abnormal, women completed subsequent 3-hour oral glucose tolerance tests (OGTTs) to screen for gestational diabetes mellitus (GDM). We assessed both continuous GCT glucose levels and 4 categories of glucose tolerance (normal glycemia [reference], isolated hyperglycemia, impaired glucose tolerance, GDM). We used multinomial logistic regression to estimate associations of PFAS with glucose tolerance categories. We used multivariable linear regression and Bayesian kernel machine regression (BKMR) to assess individual and joint effects of PFAS on continuous GCT glucose levels, respectively. We evaluated effect modification by maternal age and race/ethnicity.

RESULTS

PFAS were not associated with glucose tolerance categories. In BKMR analyses, we observed a positive association between ln-perfluorooctane sulfonate (PFOS) and glucose levels (Δ25th to 75th percentile: 6.2 mg/dL, 95% CI, 1.1-11.3) and an inverse-U shaped association between 2-(N-perfluorooctane sulfonamide) acetate and glucose levels. Individual linear regression results were similar. We found suggestive evidence that associations varied by age and racial/ethnic group.

CONCLUSION

Certain PFAS may alter glucose homeostasis during pregnancy, but may not be associated with overt GDM.

Concomitant exposure to area-level poverty, ambient air volatile organic compounds, and cardiometabolic dysfunction: a cross-sectional study of U.S. adolescents

PURPOSE

A key to better understanding the influence of the place of residence on cardiometabolic function is the effect of concomitant exposure to both air pollution and residence in economically marginalized areas. We hypothesized that, among adolescents, the association between air pollution and cardiometabolic function is exacerbated among residents of economically marginalized areas.

METHODS

In this cross-sectional study, individual-level data on cardiometabolic function collected from a representative sample of U.S. adolescents in the National Health and Nutrition Examination Survey (n = 10,415) were merged with data on area-level poverty (U.S. decennial survey and American Community Survey) and air pollution levels (National-Scale Air Toxics Assessment ) using contemporary census-tract identifiers. We excluded respondents who were pregnant, had hypertension or diabetes or using medication for hypertension or diabetes, or with missing data on outcome variables.

RESULTS

We observed a significant interaction between area-level poverty and air pollution. Among residents of high-poverty areas, exposure to high levels of air pollution predicted a 30% elevated odds of cardiometabolic dysfunction (OR = 1.30; 95% CI: 1.04, 1.61), whereas in low-poverty areas, exposure to high levels of air pollution was not associated with elevated odds of cardiometabolic dysfunction (OR = 1.04; 95% CI: 0.85, 1.28).

CONCLUSIONS

Our findings suggest that the cardiometabolic consequences of air pollution are more readily realized among residents of economically marginalized areas. Structural remedies are discussed.

Ethnic Enclaves and Pregnancy and Behavior Outcomes Among Asian/Pacific Islanders in the USA

OBJECTIVES

Ethnic enclaves are ethnically, spatially, and socially distinct communities that may promote health through access to culturally appropriate resources and reduced exposure to discrimination. This study examined ethnic enclave residence and pregnancy outcomes among Asian/Pacific Islander (API) women in the USA.

DESIGN

We examined 9206 API births in the Consortium on Safe Labor (2002-2008). Ethnic enclaves were defined as hospital regions with high percentage of API residents (> 4%), high dissimilarity index (> 0.41; distribution of API and white residents within a geographic area), and high isolation index (> 0.03; interaction between API and white residents in an area). Gestational diabetes mellitus (GDM), preterm birth (PTB), small for gestational age (SGA), and smoking and alcohol use during pregnancy were reported in medical records supplemented with ICD-9 codes. Hierarchical logistic regression models estimated associations between ethnic enclaves and pregnancy outcomes, adjusted for maternal factors, area-level poverty, and air pollution.

RESULTS

Women in enclaves had lower odds of GDM (OR 0.61; 95%CI 0.45, 0.82), PTB (OR 0.74; 95%CI 0.56, 0.99), and SGA (OR 0.68; 95%CI 0.52, 0.89) compared with women in non-enclaves. Prenatal smoking and alcohol use appeared less likely in enclaves, but estimates were imprecise. Within enclaves, about 10.5% of homes speak an API language, compared with 6.0% in non-enclaves. The mean percent of foreign-born API populations was 67.4% in enclaves and 68.8% in non-enclaves.

CONCLUSIONS

API women residing in ethnic enclaves had better pregnancy outcomes than API women residing in non-enclave areas. Access to culturally appropriate social supports and resources may be important for health promotion among API populations.