Association of metabolites of benzene and toluene with lipid profiles in Korean adults: Korean National Environmental Health Survey (2015-2017)

Vascular toxicity of benzene series released from decorative materials

The health risks associated with benzene series emissions from decorative materials have become a paramount concern in indoor air quality assessments, particularly given their established link with cardiovascular diseases, such as hypertension and atherosclerosis. Despite epidemiological evidence supporting this correlation, the underlying mechanisms remain under debate. This research comprehensively reviewed contemporary epidemiological studies on the cardiovascular impacts of benzene series emissions. It concentrated on the elucidation of their vascular toxicity, encompassing structural damage to vascular tissues, impaired vasoconstrictive-diastolic function, and abnormal lipid accumulation. By illuminating these research advancements, this study aimed to outline directions for future investigations and furnish insights into mitigating the risk of cardiovascular diseases stemming from benzene-contaminated decorative materials, ultimately contributing to public health protection.

Hematological biochemical and liver function changes associated with BTEX exposure in a six year retrospective cohort study

This 6-year retrospective cohort study aimed to investigate the health effects of exposure to BTEX compounds in a petroleum products distribution company in Iran. Blood samples were collected annually from both exposed and control groups at the start of each work shift and analyzed for a range of hematological, biochemical, and liver function parameters, including lymphocyte, neutrophil, ALT, AST, Hb, HCT, MCV, MCHC, platelet, WBC, RBC, TG, LDL, and HDL. Annual monitoring of BTEX exposure was conducted using the standard NIOSH 1501 method. The study found significant time-dependent effects of BTEX exposure on liver function, lipid profile, and hematopoietic parameters. Linear mixed-effects models revealed consistent increases in ALT, TG, Hb, and MCHC levels in the exposed group compared to the control group, with statistically significant differences (β = 1.10, p = 0.029; β = 6.56, p = 0.016; β = 0.85, p = 0.013; β = 0.87, p = 0.027). Additionally, the model fitting results for LDL indicated a decreasing trend in the exposed group compared to the control group, which was also statistically significant (β = -1.76, p = 0.034). These findings suggest that long-term exposure to BTEX compounds may have adverse health effects on the liver, lipid profile, and hematopoietic system. Further research with larger sample sizes and longer follow-up periods is needed to confirm these findings and explore the long-term health effects of BTEX exposure.

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

Potential Effects of Low-Level Toluene Exposure on the Nervous System of Mothers and Infants

In day-to-day living, individuals are exposed to various environmentally hazardous substances that have been associated with diverse diseases. Exposure to air pollutants can occur during breathing, posing a considerable risk to those with environmental health vulnerabilities. Among vulnerable individuals, maternal exposure can negatively impact the mother and child in utero. The developing fetus is particularly vulnerable to environmentally hazardous substances, with potentially greater implications. Among air pollutants, toluene is neurotoxic, and its effects have been widely explored. However, the impact of low-level toluene exposure in daily life remains unclear. Herein, we evaluated 194 mothers and infants from the Growing children's health and Evaluation of Environment (GREEN) cohort to determine the possible effects of early-life toluene exposure on the nervous system. Using Omics experiments, the effects of toluene were confirmed based on epigenetic changes and altered mRNA expression. Various epigenetic changes were identified, with upregulated expression potentially contributing to diseases such as glioblastoma and Alzheimer's, and downregulated expression being associated with structural neuronal abnormalities. These findings were detected in both maternal and infant groups, suggesting that maternal exposure to environmental hazardous substances can negatively impact the fetus. Our findings will facilitate the establishment of environmental health policies, including the management of environmentally hazardous substances for vulnerable groups.

Association of Urinary Benzene Metabolite and the Ratio of Triglycerides to High-Density Lipoprotein Cholesterol: A Cross-Sectional Study Using the Korean National Environmental Health Survey (2018-2020)

The aim of this study was to investigate the association between benzene and toluene, and the ratio of triglycerides to high-density lipoprotein cholesterol (TG/HDL-C). This cross-sectional study analyzed 1928 adults using nationally representative data from the Korean National Environmental Health Survey (KoNEHS) Cycle 4 (2018-2020). Urinary trans, trans-muconic acid (t,t-MA) and benzylmercapturic acid (BMA) were measured by high-performance liquid chromatography-mass spectrometry (HPLC-MS/MS), and high-density lipoprotein cholesterol (HDL-C) and triglycerides (TGs) were analyzed by colorimetry. Survey logistic regression analysis was applied to examine the association between urinary t,t-MA and BMA and the TG/HDL-C ratio. Urinary t,t-MA is significantly associated with an elevated TG/HDL-C ratio in both men and women (for men, OR [95% (CI)]: 2nd quartile: 2.10 [1.04, 4.22]; 3rd quartile: 2.13 [0.98, 4.62]; 4th quartile: 2.39 [1.05, 5.45]; for women, OR [95% (CI)]: 2nd quartile: 1.21 [0.71, 2.06]; 3rd quartile: 1.65 [0.94, 2.90]; 4th quartile: 1.78 [1.01, 3.11]), with significant dose-response relationships (P for trend: for men, 0.029; women, 0.024). This study shows that environmental exposure to benzene is associated with the TG/HDL-C ratio in the Korean general population. This suggests that more stringent environmental health policies are needed to reduce benzene exposure.

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.

Study on the correlation and interaction between metals and dyslipidemia: a case-control study in Chinese community-dwelling elderly

Previous studies on the association between metals and dyslipidemia are not completely consistent. There are few studies investigating the relationship between mixed metal exposure and dyslipidemia as well as the effects of metals on dyslipidemia in community-dwelling elderly. To evaluate the correlations and interaction effect between the urinary concentrations of metals and the risk of dyslipidemia in community-dwelling elderly. We designed a case-control study to assess the correlation between urine metals and dyslipidemia in elderly people in the Yinchuan. The urinary levels of 13 metals, including calcium, vanadium, iron, cobalt, zinc, copper, arsenic, selenium, molybdenum, cadmium, tellurium, and thallium, were measured by inductively coupled plasma-mass spectrometry (ICP-MS), and the blood biochemical analyzer was used to measure the blood lipid levels of 3384 senior individuals from four different areas of Yinchuan city. Logistic regression and restricted cubic splines (RCS) were used to explore the correlation and dose-response relationship between urinary metals and the risk of dyslipidemia. Least absolute shrinkage and selection operator (LASSO) regression was used to select metals, and then weighted quantile sum (WQS) regression was used to explore the weight of each metal in mixed metals. Bayesian kernel machine regression (BKMR) was used to explore the interactions between metals on dyslipidemia risk. (1) After selection by LASSO regression, in the multi-metal model, compared with the lowest quartile, the adjusted ORs (95%CI) of the highest quartiles were 0.47 (0.37-0.60) for Fe, 1.43 (1.13-1.83) for Zn, 1.46 (1.11-1.92) for As, 0.59 (0.44-0.80) for Se, 1.53 (1.18-2.00) for Mo, and 1.36 (1.07-1.73) for Te. (2) In the WQS regression model, Fe and Mo accounted for the largest weight in the negative and positive effects of dyslipidemia, respectively. (3) In the BKMR model, there may be a positive interaction between Te and Se on dyslipidemia. Among the mixed metals, Fe, As, Se, Mo, and Te were associated with the prevalence of dyslipidemia, with Fe and Mo contributing the most. There may be certain interactions between Te and Se.

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.