Arsenic-induced dyslipidemia in male albino rats: comparison between trivalent and pentavalent inorganic arsenic in drinking water

Evaluation of Lipids and Lipid-Related Transcripts in Human and Ovine Theca Cells and an in Vitro Mouse Model Exposed to the Obesogen Chemical Tributyltin

BACKGROUND

Exposure to obesogenic chemicals has been reported to result in enhanced adipogenesis, higher adipose tissue accumulation, and reduced ovarian hormonal synthesis and follicular function. We have reported that organotins [tributyltin (TBT) and triphenyltin (TPT)] dysregulate cholesterol trafficking in ovarian theca cells, but, whether organotins also exert lipogenic effects on ovarian cells remains unexplored.

OBJECTIVE

We investigated if environmentally relevant exposures to organotins [TBT, TPT, or dibutyltin (DBT)] induce lipid dysregulation in ovarian theca cells and the role of the liver X receptor (LXR) in this effect. We also tested the effect of TBT on oocyte maturation and neutral lipid accumulation, and lipid-related transcript expression in cumulus cells and preimplantation embryos.

METHODS

Primary theca cell cultures derived from human and ovine ovaries were exposed to TBT, TPT, or DBT (1, 10, or 50   ng / ml ). The effect of these chemical exposures on neutral lipid accumulation, lipid abundance and composition, lipid homeostasis-related gene expression, and cytokine secretion was evaluated using liquid chromatography-mass spectrometry (LC-MS), inhibitor-based methods, cytokine secretion, and lipid ontology analyses. We also exposed murine cumulus-oocyte complexes to TBT and evaluated oocyte maturation, embryo development, and lipid homeostasis-related mRNA expression in cumulus cells and blastocysts.

RESULTS

Exposure to TBT resulted in higher intracellular neutral lipids in human and ovine primary theca cells. In ovine theca cells, this effect was dose-dependent, independent of cell stage, and partially mediated by LXR. DBT and TPT resulted in higher intracellular neutral lipids but to a lesser extent in comparison with TBT. More than 140 lipids and 9 cytokines were dysregulated in TBT-exposed human theca cells. Expression of genes involved in lipogenesis and fatty acid synthesis were higher in theca cells, as well as in cumulus cells and blastocysts exposed to TBT. However, TBT did not impact the rates of oocyte maturation or blastocyst development.

DISCUSSION

TBT induced dyslipidemia in primary human and ovine theca cells, which may be responsible for some of the TBT-induced fertility dysregulations reported in rodent models of TBT exposure. https://doi.org/10.1289/EHP13955.

Association between blood arsenic concentration and dyslipidemia: Mediating effect of lipid peroxidation in the elderly

BACKGROUND

The earlier investigations have revealed heavy metals exposure is implicated in the pathogenesis of dyslipidemia. The goal was to evaluated the relationship of blood arsenic (As) concentration with dyslipidemia in the elderly through a cross-sectional study.

METHODS

The entire 360 elderly population were selected. Fasting blood specimens, demographic information, and clinical characteristics were obtained. The concentration of blood As was detected using ICP-MS. Serum 8-iso-PGF2α, a biomarker of lipid peroxidation, was measured by ELISA.

RESULTS

Pearson correlative analysis hinted there were strong relationships of blood As with liver function indices in the elderly. Besides, blood As was positively associated with total cholesterol (TC), triglyceride (TG), low density lipoprotein (LDL-C), and apolipoprotein A-I (ApoA I). Further multivariate linear and logistic regression suggested that the incidences of TC and LDL-C elevation were upregulated with the rising tertiles of blood As. Blood As was positively related with the prevalence of dyslipidemia (OR=3.609; 95%CI: 1.353, 6.961). Additionally, serum 8-iso-PGF2α was dramatically and positively linked to the levels of blood As and lipid profiles. Mediation analyses verified that 8-iso-PGF2α partially mediated the correlations between blood As with TC (36.63%) and LDL-C (34.03%).

CONCLUSION

Blood As concentration is positively related to lipid profiles in the elderly. Higher blood As concentration elevates the prevalence of dyslipidemia. Lipid peroxidation partially mediates the correlation of As exposure with dyslipidemia.

Arsenic and adipose tissue: an unexplored pathway for toxicity and metabolic dysfunction

Arsenic-contaminated drinking water can induce various disorders by disrupting lipid and glucose metabolism in adipose tissue, leading to insulin resistance. It inhibits adipocyte development and exacerbates insulin resistance, though the precise impact on lipid synthesis and lipolysis remains unclear. This review aims to explore the processes and pathways involved in adipogenesis and lipolysis within adipose tissue concerning arsenic-induced diabetes. Although arsenic exposure is linked to type 2 diabetes, the specific role of adipose tissue in its pathogenesis remains uncertain. The review delves into arsenic's effects on adipose tissue and related signaling pathways, such as SIRT3-FOXO3a, Ras-MAP-AP-1, PI(3)-K-Akt, endoplasmic reticulum stress proteins, CHOP10, and GPCR pathways, emphasizing the role of adipokines. This analysis relies on existing literature, striving to offer a comprehensive understanding of different adipokine categories contributing to arsenic-induced diabetes. The findings reveal that arsenic detrimentally impacts white adipose tissue (WAT) by reducing adipogenesis and promoting lipolysis. Epidemiological studies have hinted at a potential link between arsenic exposure and obesity development, with limited research suggesting a connection to lipodystrophy. Further investigations are needed to elucidate the mechanistic association between arsenic exposure and impaired adipose tissue function, ultimately leading to insulin resistance.

Ebselen: A Review on its Synthesis, Derivatives, Anticancer Efficacy and Utility in Combating SARS-COV-2

Ebselen is a selenoorganic chiral compound with antioxidant properties comparable to glutathione peroxidase. It is also known as 2-phenyl-1,2-benzisoselenazol-3(2H)-one. In studies examining its numerous pharmacological activities, including antioxidant, anticancer, antiviral, and anti- Alzheimer's, ebselen has demonstrated promising results. This review's primary objective was to emphasize the numerous synthesis pathways of ebselen and their efficacy in fighting cancer. The data were collected from multiple sources, including Scopus, PubMed, Google Scholar, Web of Science, and Publons. The starting reagents for the synthesis of ebselen are 2-aminobenzoic acid and N-phenyl benzamide. It was discovered that ebselen has the ability to initiate apoptosis in malignant cells and prevent the formation of new cancer cells by scavenging free radicals. In addition, ebselen increases tumor cell susceptibility to apoptosis by inhibiting TNF-α mediated NF-kB activation. Ebselen can inhibit both doxorubicin and daunorubicin-induced cardiotoxicity. Allopurinol and ebselen administered orally can be used to suppress renal ototoxicity and nephrotoxicity. Due to excessive administration, diclofenac can induce malignancy of the gastrointestinal tract, which ebselen can effectively suppress. Recent research has demonstrated ebselen to inhibit viral function by binding to cysteinecontaining catalytic domains of various viral proteases. It was discovered that ebselen could inhibit the catalytic dyad function of Mpro by forming an irreversible covalent bond between Se and Cys145, thereby altering protease function and inhibiting SARS-CoV-2. Ebselen may also inhibit the activation of endosomal NADPH oxidase of vascular endothelial cells, which is believed to be required for thrombotic complications in COVID-19. In this review, we have included various studies conducted on the anticancer effect of ebselen as well as its inhibition of SARS-CoV-2.

Non-coding RNA therapeutics: Towards a new candidate for arsenic-induced liver disease

Arsenic, a metalloid toxicant, has caused serious environmental pollution and is presently a global health issue. Long-term exposure to arsenic causes diverse organ and system dysfunctions, including liver disease. Arsenic-induced liver disease comprises a spectrum of liver pathologies, ranging from hepatocyte damage, steatosis, fibrosis, to hepatocellular carcinoma. Various mechanisms, including an imbalance in redox reactions, mitochondrial dysfunction and epigenetic changes, participate in the pathogenesis of arsenic-induced liver disease. Altered epigenetic processes involved in its initiation and progression. Dysregulated modulations of non-coding RNAs (ncRNAs), including miRNAs, lncRNAs and circRNAs, exert regulating effects on these processes. Here, we have reviewed the underlying pathogenic mechanisms that lead to progressive arsenic-induced liver disease, and we provide a discussion focusing on the effects of ncRNAs on dysfunctions in intercellular communication and on the activation of hepatic stellate cells and malignant transformation of hepatocytes. Further, we have discussed the roles of ncRNAs in intercellular communication via extracellular vesicles and cytokines, and have provided a perspective for the application of ncRNAs as biomarkers in the early diagnosis and evaluation of the pathogenesis of arsenic-induced liver disease. Further investigations of ncRNAs will help us to understand the nature of arsenic-induced liver disease and to identify biomarkers and therapeutic targets.

Assessment of roadside pollution by heavy metals: A case study from the District of Bani Kinanah, Irbid, Northern Jordan

The District of Bani Kenanah is home to natural reserves, forests, local agricultural practices, and a multitude of historical and cultural sites. The majority of the population in the study area is employed in the agricultural sector, which is dominated by olive tree cultivation and the production of premium olive oil. The current study aimed to assess the degree of roadside soil pollution and predict the potential ecological impacts of Pb, Cd, Zn, Cr, Ni, Mn, Cu, Fe, and Co. Therefore, 30 soil samples were collected and analyzed with a Flame atomic absorption spectrophotometer for the aforementioned metals. The spatial distribution maps of these metals were generated by inverse distance weighted (IDW) interpolation in ArcGIS 10.3. The values of heavy metals (HMs) in the study were lower than the international standards for soil quality. The soil was classified as moderately to substantially enriched with Cd, Pb, and Zn based on the EF values. However, the indices of geo-accumulation (Igeo), contamination factor (CF), and potential ecological risk (RI) generally revealed minor metallic contamination. The traffic and agricultural activities were the potential sources of Cd, Pb, and Zn in the study area. Incorporating HMs analysis with GIS maps was beneficial for assessing soil pollution.

Assessment of sub-chronic oral toxicity of Nityanand Rasa: An ayurvedic herbo-metallic formulation

ETHNOPHARMACOLOGICAL RELEVANCE

Nityananda Rasa (NR) is an ayurvedic herbo-metallic formulation used to treat gout, obesity, hypothyroidism, elephantiasis, and other diseases. However, its safety is a concern owing to the use of heavy metals like mercury and arsenic.

AIM OF THE STUDY

To study the sub-chronic oral toxicity of NR on albino wistar rats for safety evaluation.

MATERIALS AND METHODS

The male and female albino wistar rats were administered a daily dose of 30 (low), 300 (medium) and 600 (high) mg/kg BW/day of NR for 90-day period. The body weight and feed consumption were monitored once a week. After 90 days, blood and vital organs were harvested for genotoxicity, hematology, biochemistry, histopathology, gene expression and the biodistribution analysis.

RESULTS

There was no mortality or severe behavioural changes observed in rats. Significant changes in biochemical enzyme levels were seen at medium and high doses of NR i. e. 300 and 600 mg/kg BW/day respectively. No hematological changes were observed. Mild histopathological changes seen at high dose of NR which were found in concurrence with the biochemical alterations in liver and brain. There was mild genotoxicity and no detectable level of mercury but significant arsenic level in blood at high dose. Gene expression was mildly affected.

CONCLUSIONS

NR induced moderate toxic effects at high dose but can be considered safe at therapeutic doses.

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

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

The effects of sucrose and arsenic on muscular insulin signaling pathways differ between the gastrocnemius and quadriceps muscles

Introduction

Insulin resistance in muscle can originate from a sedentary lifestyle, hypercaloric diets, or exposure to endocrine-disrupting pollutants such as arsenic. In skeletal muscle, insulin stimulates glucose uptake by translocating GLUT4 to the sarcolemma. This study aimed to evaluate the alterations induced by sucrose and arsenic exposure in vivo on the pathways involved in insulinstimulated GLUT4 translocation in the quadriceps and gastrocnemius muscles.

Methods

Male Wistar rats were treated with 20% sucrose (S), 50 ppm sodium arsenite (A), or both (A+S) in drinking water for 8 weeks. We conducted an intraperitoneal insulin tolerance (ITT) test on the seventh week of treatment. The quadriceps and gastrocnemius muscles were obtained after overnight fasting or 30 min after intraperitoneal insulin injection. We assessed changes in GLUT4 translocation to the sarcolemma by cell fractionation and abundance of the proteins involved in GLUT4 translocation by Western blot.

Results

Male rats consuming S and A+S gained more weight than control and Atreated animals. Rats consuming S, A, and A+S developed insulin resistance assessed through ITT. Neither treatments nor insulin stimulation in the quadriceps produced changes in GLUT4 levels in the sarcolemma and Akt phosphorylation. Conversely, A and A+S decreased protein expression of Tether containing UBX domain for GLUT4 (TUG), and A alone increased calpain-10 expression. All treatments reduced this muscle's protein levels of VAMP2. Conversely, S and A treatment increased basal GLUT4 levels in the sarcolemma of the gastrocnemius, while all treatments inhibited insulin-induced GLUT4 translocation. These effects correlated with lower basal levels of TUG and impaired insulin-stimulated TUG proteolysis. Moreover, animals treated with S had reduced calpain-10 protein levels in this muscle, while A and A+S inhibited insulin-induced Akt phosphorylation.

Conclusion

Arsenic and sucrose induce systemic insulin resistance due to defects in GLUT4 translocation induced by insulin. These defects depend on which muscle is being analyzed, in the quadriceps there were defects in GLUT4 retention and docking while in the gastrocnemius the Akt pathway was impacted by arsenic and the proteolytic pathway was impaired by arsenic and sucrose.

Disease-associated metabolic pathways affected by heavy metals and metalloid

Increased exposure to environmental heavy metals and metalloids and their associated toxicities has become a major threat to human health. Hence, the association of these metals and metalloids with chronic, age-related metabolic disorders has gained much interest. The underlying molecular mechanisms that mediate these effects are often complex and incompletely understood. In this review, we summarize the currently known disease-associated metabolic and signaling pathways that are altered following different heavy metals and metalloids exposure, alongside a brief summary of the mechanisms of their impacts. The main focus of this study is to explore how these affected pathways are associated with chronic multifactorial diseases including diabetes, cardiovascular diseases, cancer, neurodegeneration, inflammation, and allergic responses upon exposure to arsenic (As), cadmium (Cd), chromium (Cr), iron (Fe), mercury (Hg), nickel (Ni), and vanadium (V). Although there is considerable overlap among the different heavy metals and metalloids-affected cellular pathways, these affect distinct metabolic pathways as well. The common pathways may be explored further to find common targets for treatment of the associated pathologic conditions.

Lysinibacillus sphaericus mediates stress responses and attenuates arsenic toxicity in Caenorhabditis elegans

Exposure to toxic metals alters host response and that leads to disease development. Studies have revealed the effects of metals on microbial physiology, however, the role of metal resistant bacteria on host response to metals is unclear. The hypothesis that xenobiotic interactions between gut microbes and arsenic influence the host physiology and toxicity was assessed in a Caenorhabditis elegans model. The arsenic-resistant Lysinibacillus sphaericus B1CDA was fed to C. elegans to determine the host responses to arsenic in comparison to Escherichia coli OP50 food. L. sphaericus diet extended C. elegans lifespan compared to E. coli diet, with an increased expression of genes involved in lifespan, stress response and immunity (hif-1, hsp-16.2, mtl-2, abf-2, clec-60), as well as reduced fat accumulation. Arsenic-exposed worms fed L. sphaericus also had a longer lifespan than those fed E. coli and had an increased expression of genes involved in cytoprotection, stress resistance (mtl-1, mtl-2) and oxidative stress response (cyp-35A2, isp-1, ctl-2, sod-1), together with a decreased accumulation of reactive oxygen species (ROS). In comparison with E. coli, L. sphaericus B1CDA diet increased C. elegans fitness while detoxifying arsenic induced ROS and extending lifespan.

The impact of essential and toxic elements on cardiometabolic risk factors in adults and older people

BACKGROUND AND AIM

Evidence suggests an association between essential and toxic elements and the worsening of cardiometabolic risk factors. This study aimed to investigate the concentrations of zinc, copper, selenium, arsenic, cadmium, and mercury and their relationship with cardiometabolic risk factors in adults and older people.

METHODS

This cross-sectional study was carried out with 112 adults with a mean age of 59 (sd 14) years old and a BMI of 29.30 (sd 5.11) Kg/m². The subject's weight and height were measured for body mass index (BMI) calculation, classified according to the cut-off points recommended by the World Health Organization (WHO). We evaluated sociodemographic, clinical, lifestyle, waist circumference - WC, visceral adiposity index - VAI, glycemic lipid profile, blood pressure, and high-sensitive C-reactive protein (hs-CRP). Cardiovascular risk was defined by The Global Risk Score (GRS) score. Plasma zinc, selenium, copper levels, urinary arsenic, cadmium, and mercury levels were measured using the inductively coupled plasma mass spectrometry technique (ICP-MS).

RESULTS

There was a negative association between urinary arsenic and VAI (β - 0.03, p < 0.01), triglycerides (β - 1.10, p < 0.01), and VLDL cholesterol (β - 0.14, p = 0.02). Plasma copper and copper/zinc ratio were positively associated with fasting glucose and hs-CRP (β 0.38, p < 0.01; β 36.02, p = 0.01, β 0.004, p < 0.01, β 0.68, p < 0.001, respectively). Urinary arsenic (β - 0.14, p = 0.04) and cadmium (β - 36.42, p = 0.04) were negatively associated with systolic blood pressure. Also, urinary cadmium was negatively associated with diastolic blood pressure (β - 21.55, p = 0.03), and urinary mercury showed an opposite behavior (β 1.45, p = 0.03).

CONCLUSION

Essential and toxic elements in urine and plasma could be potential biomarkers for cardiovascular risk factors. A healthy lifestyle should be adopted; in addition, government policies should be developed to guarantee sustainable production and a safe environment.

Arsenic Exposure through Dietary Intake and Associated Health Hazards in the Middle East

Dietary arsenic (As) contamination is a major public health issue. In the Middle East, the food supply relies primarily on the import of food commodities. Among different age groups the main source of As exposure is grains and grain-based food products, particularly rice and rice-based dietary products. Rice and rice products are a rich source of core macronutrients and act as a chief energy source across the world. The rate of rice consumption ranges from 250 to 650 g per day per person in South East Asian countries. The source of carbohydrates through rice is one of the leading causes of human As exposure. The Gulf population consumes primarily rice and ready-to-eat cereals as a large proportion of their meals. Exposure to arsenic leads to an increased risk of non-communicable diseases such as dysbiosis, obesity, metabolic syndrome, diabetes, chronic kidney disease, chronic heart disease, cancer, and maternal and fetal complications. The impact of arsenic-containing food items and their exposure on health outcomes are different among different age groups. In the Middle East countries, neurological deficit disorder (NDD) and autism spectrum disorder (ASD) cases are alarming issues. Arsenic exposure might be a causative factor that should be assessed by screening the population and regulatory bodies rechecking the limits of As among all age groups. Our goals for this review are to outline the source and distribution of arsenic in various foods and water and summarize the health complications linked with arsenic toxicity along with identified modifiers that add heterogeneity in biological responses and suggest improvements for multi-disciplinary interventions to minimize the global influence of arsenic. The development and validation of diverse analytical techniques to evaluate the toxic levels of different As contaminants in our food products is the need of the hour. Furthermore, standard parameters and guidelines for As-containing foods should be developed and implemented.

Arsenic Toxicity on Metabolism and Autophagy in Adipose and Muscle Tissues

Arsenic, a naturally occurring metalloid derived from the environment, has been studied worldwide for its causative effects in various cancers. However, the effects of arsenic toxicity on the development and progression of metabolic syndrome, including obesity and diabetes, has received less attention. Many studies suggest that metabolic dysfunction and autophagy dysregulation of adipose and muscle tissues are closely related to the development of metabolic disease. In the USA, arsenic contamination has been reported in some ground water, soil and grain samples in major agricultural regions, but the effects on adipose and muscle tissue metabolism and autophagy have not been investigated much. Here, we highlight arsenic toxicity according to the species, dose and exposure time and the effects on adipose and muscle tissue metabolism and autophagy. Historically, arsenic was used as both a poison and medicine, depending on the dose and treatment time. In the modern era, arsenic intoxication has significantly increased due to exposure from water, soil and food, which could be a contributing factor in the development and progression of metabolic disease. From this review, a better understanding of the pathogenic mechanisms by which arsenic alters metabolism and autophagy regulation could become a cornerstone leading to the development of therapeutic strategies against arsenic-induced toxicity and metabolic disease.

Associations of total urinary arsenic with total cholesterol and high-density lipoprotein among 12-17-year-old participants from the 2009-2016 NHANES cycles: A cross-sectional study

INTRODUCTION

Hypertension and diabetes are highly prevalent among US adults. Arsenic exposure is associated with these cardiometabolic morbidities but the relationship between arsenic exposure and cholesterol markers of cardiometabolic disease has not been elucidated, especially at younger ages, when many chronic diseases may initiate. This study examined the association of total urinary arsenic with total cholesterol (TC) and high-density lipoprotein cholesterol (HDL) and explored effect modification by weight status.

METHODS

The study sample consisted of 12-17-year-old participants with complete data from the 2009-2016 National Health and Nutrition Examination Survey cycles. The cross-sectional associations of creatinine-adjusted total urinary arsenic with TC and HDL were assessed using multivariable linear regression models with survey weights. Three models were built, adjusting for varying combinations of age, gender, race/ethnicity, weight status, survey cycle, family income to poverty ratio, reference person education level, arsenobetaine, and dimethylarsinic acid (DMA). Model adjustments for arsenobetaine approximated inorganic arsenic exposure, and further adjustment for DMA approximated unmethylated inorganic arsenic exposure. We also explored weight status (underweight/healthy, overweight, and obese) as a potential effect modifier of these relationships using stratified analyses and interaction tests.

RESULTS

The final analytical sample consisted of 1,177 12-17-year-old participants. After adjusting for covariates and arsenobetaine, creatinine-adjusted arsenic was positively associated with HDL levels (β = 0.063; 95% CI: 0.007, 0.119). Upon further adjustment for DMA, creatinine-adjusted arsenic was positively associated with HDL levels (β = 0.079; 95% CI: 0.015, 0.143) and TC levels (β = 0.258; 95% CI: 0.002, 0.515). No effect modification by weight status was observed.

CONCLUSIONS

We found a positive association of approximated unmethylated inorganic arsenic exposure with TC, and contrary to our expectation, with HDL. There was no effect modification by weight status. Our findings should be confirmed by conducting longitudinal studies among adolescents exposed to low-level arsenic and focusing specifically on urinary inorganic arsenic concentrations.

Arsenic Induces Continuous Inflammation and Regulates Th1/Th2/Th17/Treg Balance in Liver and Kidney In Vivo

Numerous studies on arsenic-induced hepatonephric toxicity including cancer have been reported. Given that chronic inflammatory response and immune imbalance are associated with oncogenesis, we investigated whether arsenic could influence the hepatic and nephritic expression of inflammatory factors and the differentiation of T cells. Mice were exposed to NaAsO₂ (0, 25, and 50 mg/L) for 1 and 3 months. Our data showed the destruction of the structure and inflammatory infiltration in the liver. The arsenic markedly increased the activity of serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST). The myeloperoxidase (MPO) activities increased in the liver at 25 and 50 mg/L arsenic for 3 months as well as in the kidney at both 1 and 3 months. An increased expression of inflammatory indicators (IL-1β, IL-12, and TNF-α) at 25 and 50 mg/L arsenic for 1 and 3 months in the liver and kidney, as well as IL-1β in the liver for 3 months and in the kidney at 50 mg/L for 1 and 3 months were demonstrated in our experiments. Besides, a definite tendency toward Th1/Th17 cytokines in the liver while Th2/Th17 cytokines in kidney was also observed by arsenic. Moreover, arsenic enhanced the expression of MAPK/Nrf2/NF-κB signaling molecules. In conclusion, the results of the study suggested that arsenic induces continuous immune-inflammatory responses in the liver and kidney.

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

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

Sexual dimorphism in inorganic mercury toxicokinetics and the attendant lipotoxic and non-lipotoxic dyslipidemia in the rat

The influence of variability in the biology of living organisms is poorly appreciated in toxicology. However, multiple lines of evidence indicate that sex-differences modulate toxicokinetics and toxicodynamics from cellular/molecular to whole animal levels resulting in different toxic responses of living organisms to xenobiotics exposure. In order to investigate the influence of sex in inorganic mercury (Hg) exposure, male and female Wistar rats were exposed to 0.5, 1.0 and 1.5 mg Hg/kg body weight orally as HgCl₂ twice a week for 12 weeks. Higher Hg levels in the females (except heart) as compared to males were observed in the animals. At the highest dose of inorganic Hg, female renal Hg content was 3.3 times higher than that of the males. Mixed sexual dimorphism characterised circulating-lipid- and organ-lipid lipotoxic and non-lipotoxic dyslipidemia. The highest dose of inorganic Hg, induced hypercholesterolemia in the males as opposed to hypocholesterolemia in the female. Plasma and erythrocyte free fatty acids increased in both sexes, although the increase was more pronounced in the male. Reverse cholesterol transport was inhibited in the male at the highest dose of Hg, whereas female HDL became enriched with cholesterol. Female erythrocytes had all their lipids increased, whereas only male erythrocyte triglyceride increased. Brain cholesterol and phospholipids, and splenic phospholipids were depleted in both sexes. Our findings indicate that inorganic Hg exposure appears to affect Hg and lipid kinetics differently in both sexes, thus underscoring the need to develop sex-tailored approaches in the treatment of metal toxicosis and its metabolic outcomes.

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The influence of sex in inorganic Hg exposure was investigated in the rat.

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Higher Hg levels in females compared to males were observed.

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Sexual dimorphism characterised inorganic Hg-induced dyslipidemia.

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Inorganic Hg exposure affects Hg and lipid kinetics differently in both sexes.

Biochemical investigation of human exposure to aflatoxin M1 and its association with risk factors of diabetes mellitus

Recently, aflatoxin M1 (AFM1) has emerged as a major health concern owing to its exposure to human being via consumption of milk, dairy products, and food commodities, and this has a strong association with risk factors that may lead to the onset of type 2 diabetes mellitus (T2DM) and various other associated metabolic disorders. This study was conducted to investigate the exposure to AFM1 and its association with sociodemographic features and risk factors of T2DM. Urine and blood samples from 672 participants were collected to investigate the concentration of AFM1 in urine and glucose, glycosylated hemoglobin (HbA1c), insulin, α-amylase, dipeptidyl peptidase-IV (DPP-IV), free fatty acids (FFAs), triglycerides (TGs), high-density lipoprotein cholesterol (HDL-chol), interleukine-6 (IL-6), tumor necrosis factor-α (TNF-α), malondialdehyde (MDA), glutathione (GSH), superoxide dismutase (SOD), creatinine, uric acid, blood urea nitrogen (BUN), aspartate aminotransferase (AST), and alanine transaminase (ALT) from the blood of study participants. Association of exposure to AFM1 with sociodemographic features and risk factors of T2DM was determined using person correlation coefficient (r), coefficient of determination (R²), and 95% confidence interval, and the level of significance (P<0.05) was measured by Student's unpaired t-test. Among the participants in which AFM1 was detected, 62.91% of participants were found to be diabetic and 37.09% of participants were found to be non-diabetic. Further to this, it was also found that concentration of AFM1 in the urine of diabetic participants was found to be higher (P<0.05) as compared to that in non-diabetic participants. Association of AFM1 exposure with risk factors of T2MD exhibits that exposure to AFM1 was responsible for the induction of inflammatory responses and oxidative stress that may lead to the onset of impaired insulin secretion and metabolism of carbohydrates and ultimately the onset of T2DM and associated metabolic disorders. Hence, it can be summarized that exposure to AFM1 is one of the causative factors that may lead to potentiate the several risk factors notably inflammatory responses and oxidative stress that ultimately induce the pathogenesis of T2DM and associated metabolic disorders. The key findings of this study suggest that human population who are at greater risk of AFM1 exposure can develop T2DM and other associated metabolic risk factors.

Virgin Coconut Oil Resists Arsenic-Induced Cerebral Neurotoxicity and Cholesterol Imbalance via Suppression of Oxidative Stress, Adenosine Deaminase and Acetylcholinesterase Activities in Rats

Arsenic (As) is a classic neurotoxicant; its pathogenesis is associated with oxidative stress and oxidative stress-mediated cholinergic deficits. This study explored antioxidant activity of virgin coconut oil (VCO) against sodium arsenite-induced oxidative stress-mediated cerebral neurotoxicity in rats. Eighteen rats were divided into 3 groups- Normal control, As control and VCO + As. The VCO (5 mL/kg) was given once daily by oral gavage from day 1 to day 21, while As (10 mg/kg) was given once daily by oral gavage from day 15 to day 21. Cerebral superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), malondialdehyde (MDA), adenosine deaminase (ADA) and acetylcholinesterase (AchE) activities were analysed. Nitric oxide (NO), lipid profile, phospholipid (PL), and reduced glutathione (GSH) were also evaluated in cerebral homogenate. The cerebrum was sectioned for histological analysis. Administration of As induced significant depressions in antioxidant enzymes, GSH, PL, and HDL-c compared to normal control. Levels of MDA, NO, total cholesterol and activities of ADA, AchE in the cerebrum were markedly increased by As compared to normal rats. Lipid profile indices and PL were prominently altered by As. Histopathological study supported the biochemical findings through extensive cerebral damage. In contrast, oral supplementation of VCO prior to and along with As treatment significantly attenuated the As-induced biochemical alterations and restored near-normal histology. VCO attenuates cerebral neurotoxicity by strengthening endogenous antioxidant defence and cholinergic function via counteracting free-radical-mediated arsenic toxicity.

Assessment of the hyperlipidemia risk for residents exposed to potential emitted metals in the vicinity of a petrochemical complex

Hyperlipidemia, which is associated with certain environmental factors, is a risk factor for cardiovascular disease. Heavy metals are important pollutants from industrial emissions. However, the relationship between the exposure to heavy metals and the occurrence of hyperlipidemia is limited. This study aimed to investigate the association between serum metal levels and the risk of hyperlipidemia in adults living near a petrochemical complex. Our study subjects were 959 residents aged above 35 years in 11 townships near the largest petrochemical complex in central Taiwan. The serum levels of chromium, arsenic, and mercury in the study subjects were measured. The basic characteristics of the study subjects were collected via a questionnaire survey, and the levels of blood lipid biomarkers were analyzed by health examination. The definition of hyperlipidemia was defined in the provided guidelines. Adjusted generalized linear and logistic regression models were applied to evaluate the associations between petrochemical-related metal exposure and hyperlipidemia. The study subjects had chromium, arsenic, and mercury serum levels of 3.24±3.45, 3.45±4.66, and 1.24±1.08 (μg/L), respectively, and close proximity of the study subjects to the petrochemical complex was significantly associated with increased serum metal levels. The results showed that the total cholesterol levels were significantly associated with the increased serum chromium, arsenic, and mercury levels. And, the LDL-C levels were significantly associated with the increased serum mercury levels. In addition, the increased serum arsenic and mercury levels of the study subjects were significantly associated with higher odds ratios for abnormal total cholesterol levels and the risk of hyperlipidemia. Residing in close proximity to a petrochemical complex and high arsenic and mercury exposure were associated with elevated blood lipid levels and an increased risk of hyperlipidemia among the residential population in the vicinity of the petrochemical industry.

Molecular mechanism of heavy metals (Lead, Chromium, Arsenic, Mercury, Nickel and Cadmium) - induced hepatotoxicity - A review

Heavy metals pose a serious threat if they go beyond permissible limits in our bodies. Much heavy metal's viz. Lead, Chromium, Arsenic, Mercury, Nickel, and Cadmium pose a serious threat when they go beyond permissible limits and cause hepatotoxicity. They cause the generation of ROS which in turn causes numerous injuries and undesirable changes in the liver. Epidemiological studies have shown an increase in the levels of such heavy metals in the environment posing a serious threat to human health. Epigenetic alterations have been seen in the event of exposure to such heavy metals. Apoptosis, caspase activation as well as ultrastructural changes in the hepatocytes have also been seen due to heavy metals. Inflammation involving TNF-alpha, pro-inflammatory cytokines, MAPK, ERK pathways have been seen in the event of heavy metal hepatotoxicity. All these have shown that these heavy metals pose a serious threat to human health in particular and the environment as a whole.

Coenzyme Q10 protected against arsenite and enhanced the capacity of 2,3-dimercaptosuccinic acid to ameliorate arsenite-induced toxicity in mice

BACKGROUND

Arsenic poisoning affects millions of people. The inorganic forms of arsenic are more toxic. Treatment for arsenic poisoning relies on chelation of extracellularly circulating arsenic molecules by 2,3-dimecaptosuccinic acid (DMSA). As a pharmacological intervention, DMSA is unable to chelate arsenic molecules from intracellular spaces. The consequence is continued toxicity and cell damage in the presence of DMSA. A two-pronged approach that removes extracellular arsenic, while protecting from the intracellular arsenic would provide a better pharmacotherapeutic outcome. In this study, Coenzyme Q10 (CoQ10), which has been shown to protect from intracellular organic arsenic, was administered separately or with DMSA; following oral exposure to sodium meta-arsenite (NaAsO2) - a very toxic trivalent form of inorganic arsenic. The aim was to determine if CoQ10 alone or when co-administered with DMSA would nullify arsenite-induced toxicity in mice.

METHODS

Group one represented the control; the second group was treated with NaAsO2 (15 mg/kg) daily for 30 days, the third, fourth and fifth groups of mice were given NaAsO2 and treated with 200 mg/kg CoQ10 (30 days) and 50 mg/kg DMSA (5 days) either alone or in combination.

RESULTS

Administration of CoQ10 and DMSA resulted in protection from arsenic-induced suppression of RBCs, haematocrit and hemoglobin levels. CoQ10 and DMSA protected from arsenic-induced alteration of WBCs, basophils, neutrophils, monocytes, eosinophils and platelets. Arsenite-induced dyslipidemia was nullified by administration of CoQ10 alone or in combination with DMSA. Arsenite induced a drastic depletion of the liver and brain GSH; that was significantly blocked by CoQ10 and DMSA alone or in combination. Exposure to arsenite resulted in significant elevation of liver and kidney damage markers. The histological analysis of respective organs confirmed arsenic-induced organ damage, which was ameliorated by CoQ10 alone or when co-administered with DMSA. When administered alone, DMSA did not prevent arsenic-driven tissue damage.

CONCLUSIONS

Findings from this study demonstrate that CoQ10 and DMSA separately or in a combination, significantly protect against arsenic-driven toxicity in mice. It is evident that with further pre-clinical and clinical studies, an adjunct therapy that incorporates CoQ10 alongside DMSA may find applications in nullifying arsenic-driven toxicity.

Associations between metabolic syndrome and four heavy metals: A systematic review and meta-analysis

Four most concerned heavy metal pollutants, arsenic, cadmium, lead, and mercury may share common mechanisms to induce metabolic syndrome (MetS). However, recent studies exploring the relationships between MetS and metal exposure presented inconsistent findings. We aimed to clarify the relationship between heavy metal exposure biomarkers and MetS using a meta-analysis and systematic review approach. Literature search was conducted in international and the Chinese national databases up to June 2020. Of selected studies, we extracted the relevant data and evaluated the quality of each study's methodology. We then calculated the pooled effect sizes (ESs), standardized mean differences (SMDs), and their 95% confidence intervals (CIs) using a random-effect meta-analysis approach followed by stratification analyses for control of potential confounders. Involving 55,536 participants, the included 22 articles covered 52 observational studies reporting ESs and/or metal concentrations on specific metal and gender. Our results show that participants with MetS had significantly higher levels of heavy metal exposure [pooled ES = 1.16, 95% CI: 1.09, 1.23; n = 42, heterogeneity I2 = 75.6%; and SMD = 0.22, 95% CI: 0.15, 0.29; n = 32, I2 = 94.2%] than those without MetS. Pooled ESs in the subgroups stratified by arsenic, cadmium, lead, and mercury were 1.04 (95% CI: 0.97, 1.10; n = 8, I2 = 61.0%), 1.10 (0.95, 1.27; 11, 45.0%), 1.21 (1.00, 1.48; 12, 82.9%), and 1.26 (1.06, 1.48; 11, 67.7%), respectively. Pooled ESs in the subgroups stratified by blood, urine, and the other specimen were 1.22 (95% CI: 1.08, 1.38; n = 26, I2 = 75.8%), 1.06 (1.00, 1.13; 14, 58.1%), and 2.41 (1.30, 4.43; 2, 0.0%), respectively. In conclusion, heavy metal exposure was positively associated with MetS. Further studies are warranted to examine the effects of individual metals and their interaction on the relationship between MetS and heavy metals.

Pentoxifylline Attenuates Arsenic Trioxide-Induced Cardiac Oxidative Damage in Mice

This study was undertaken to evaluate the therapeutic potential effect of pentoxifylline (PTX) against arsenic trioxide (ATO)-induced cardiac oxidative damage in mice. Thirty-six male albino mice were divided into six groups and treated intraperitoneally with normal saline (group 1), ATO (5 mg/kg; group 2), PTX (100 mg/kg; group 3), and different doses of PTX (25, 50, and 100 mg/kg; groups 4, 5, and 6, respectively) with ATO. After four weeks, the blood sample was collected for biochemical experiments. In addition, cardiac tissue was removed for assessment of oxidative stress markers and histopathological changes (such as hemorrhage, necrosis, infiltration of inflammatory cells, and myocardial degeneration). The findings showed that ATO caused a significant raise in serum biochemical markers such as lactate dehydrogenase (LDH), creatine phosphokinase (CPK) and troponin-I (cTnI), glucose, total cholesterol (TC), and triglyceride (TG) levels. In addition to histopathological changes in cardiac tissue, ATO led to the significant increase in cardiac lipid peroxidation (LPO) and nitric oxide (NO); remarkable decrease in the activity of cardiac antioxidant enzymes such as catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GPx); and the depletion of the total antioxidant capacity (TAC) and total thiol groups (TTGs). PTX was able to reduce the increased levels of serum cardiac markers (LDH, CPK, cTnI, TC, and TG), cardiac LPO, and improve antioxidant markers (TAC, TTGs, CAT, SOD, and GPx) alongside histopathologic changes. However, no significant changes were observed in elevated serum glucose and cardiac NO levels. In conclusion, the current study showed the potential therapeutic effect of PTX in the prevention of ATO-induced cardiotoxicity via reversing the oxidative stress.

Bioaccumulation of heavy metals, lipid profiles, and antioxidant status of snails (Achatina achatina) around cement factory vicinities

Some snails (Achatina spp) can be used as a biosensor of heavy metal poisoning. This study thus estimated some heavy metal levels, antioxidant markers, and lipid profiles of snails handpicked around cement factory vicinities in Ogun State, Nigeria. Snails and soil samples were collected from Oke, Ewekoro, Papalanto, and Mowodani Imeko-Afon (control site). Lead (Pb), cadmium (Cd), and arsenic (As) levels were estimated in the soil, snail foot, hemolymph, and shell using Atomic Absorption Spectrophotometry. Triacylglycerol (TAG), phospholipids (PHOL), cholesterol (CHOL), malondialdehyde (MDA), and reduced glutathione (GSH) levels, as well as glutathione-S-transferase (GST), lactate dehydrogenase (LDH), and arylesterase (AR) activities in the hemolymph, were estimated spectrophotometrically. The snails collected from the Oke site had the highest foot Pb (274.66 ± 13.50 mg/g tissue), CHOL, TAG, PHOL levels, and GST activity when compared with other sites. Snails collected from Papa had the highest Cd levels (1.79 ± 0.74 mg/kg), As (1206 ± 18.87 mg/g tissue) in the foot, and LDH activity, while Ewekoro snails had highest MDA levels and AR activities but the lowest GSH levels. Additionally, there were negative correlations between the heavy metal levels and the activities of GST and AR as well as GSH levels, while positively correlating with LDH activity and MDA level. Workers and the general public around cement factories are at a greater risk of heavy metal-induced pathologies. More so, consumption of snails around these sites may be deleterious to health.

Characterizing pollution indices and children health risk assessment of potentially toxic metal(oid)s in school dust of Lahore, Pakistan

Toxic metal pollution is a renowned environmental concern, especially to sensitive environments like school classrooms and their association with children's health. The study was planned to determine the pollution characteristics of 13 potentially toxic metal (oid)s (PTMs) and their associated children's health risk assessment from school dust samples of considerably three land-use types (residential, roadside, and industrial areas) of Lahore, Pakistan. Geo-accumulation (I_geo), pollution (PI), integrated pollution (IPI) and pollution load (PLI) indexes were used to determine the PTMs contamination and USEPA health risk assessment models were employed to assess the health risks in children. The mean concentrations of Cd, Cr, Cu, Ni, Pb, and Zn for three land-use types were found much higher than the permissible limits. Results of pollution indices revealed that school dust was strongly contaminated with Cd, Pb, and Zn whilst moderately contaminated with Cr and Cu. Moreover, the health risk assessment models revealed no significant non-cancerous risks in children with predominantly highest hazardous index (HI) of Cr in industrial (4.61E-01) and Pb in both roadside (4.30E-01) and residential (2.26E-01) area schools. According to cumulative HI of all PTMs and exposure routes, the land-use areas were in descending order as industrial > roadside > residential. The calculations of hazardous quotient (HQ) showed ingestion was the leading pathway of PTMs exposure through school dust. For carcinogenic health risk (CR), the most prominent PTM was Cr with values of 1.53E-06 in industrial area schools, found close to the tolerable range (1.0E-06). Hence, school dust of Lahore prominently contaminated with eminent PTMs triggering slight health risks predominantly by ingestion exposure to children.

Toxic Effects of Chronic Exposure to High-Fat Diet and Arsenic on the Reproductive System of the Male Mouse

Objective: Obesity is associated with reproductive disorders. Arsenic disrupts male reproduction by direct effects on the male gonads or androgens secretion. So, the present study was conducted to evaluate the toxic effects of chronic concomitant administration of high-fat diet (HF) and arsenic on the reproductive system of the male mouse. Materials and methods: In this experimental study, 72 adult male mice were randomly divided into 6 groups: low-fat diet (LF0), LF+arsenic 25 ppm, LF+arsenic 50ppm, HF0, HF+arsenic 25 ppm and, HF+arsenic 50 ppm. 24 hours after the last experimental day, plasma samples, the cauda of epididymis and testis were prepared and removed for hormonal, sperm count and histopathological assessments. Results: Testis weight and volume increased in HF0 than other groups except for LF0. Plasma LH and testosterone levels decreased in LF50, HF0, HF25, and HF50 compared to LF0. A similar effect was observed in plasma FSH levels of HF0, HF25 and HF50 groups compared with LF0. Plasma level of estradiol increased in LF50 versus to other groups. Testosterone to estradiol ratio and sperm count decreased in all groups compared to LF0. Reduced interstitial cells and large numbers of vacuoles were observed in germinal epithelium of HF0 group, that these changes were more intense in both concentrations of arsenic-treated mice. Conclusion: Present study indicated that chronic exposure to HF and arsenic-induced hypogonadotropic hypogonadism concomitant with sperm count reduction and testicular damage.

Arsenic exposure intensifies glycogen nephrosis in diabetic rats

It is known that either arsenic exposure or diabetes can impact renal function. However, it is unclear how these combined factors may influence kidney functions. Therefore, we evaluated morphological, functional, and oxidative parameters in the kidney of diabetic rats exposed to arsenic. Healthy male Wistar rats and streptozotocin-induced diabetic rats were exposed to 0 and 10 mg/L arsenate through drinking water for 40 days. Renal tissue was assessed using morphometry, mitosis and apoptosis markers, mineral proportion, oxidative stress markers, as well as the activity of antioxidant enzymes and membrane-bound adenosine triphosphatases. Arsenate intake altered glucose levels in healthy animals, but it did not reach hyperglycemic conditions. In diabetic animals, arsenate led to a remarkable increase of glycogen nephrosis in distal tubules. In these animals, additionally, the activity of catalase and glutathione S-transferase, besides the proportion of Fe, Cu, and K in renal tissue, was altered. Nevertheless, arsenate did not accumulate in the kidney and did not impact on other parameters previously altered by diabetes, including levels of malondialdehyde, Na, urea, creatinine, and apoptosis and mitosis markers. In conclusion, besides the intensification of glycogen nephrosis, the kidney was able to handle arsenate toxicity at this point, preventing arsenic deposition in the exposed groups and the impairment of renal function.

Role of thymoquinone and ebselen in the prevention of sodium arsenite-induced nephrotoxicity in female rats

The aim of this study is to investigate the protective effects of thymoquinone (TQ) and ebselen (Eb) on arsenic (As)-induced renal toxicity in female rats. Sodium arsenite was orally administrated at a dose of 20 mg/kg body weight daily for 28 days, either alone or 1 h before TQ (10 mg/kg) or Eb (5 mg/kg) administration. Renal tissue As concentration and oxidative stress markers, including lipid peroxidation (LPO), nitrite/nitrate, and glutathione (GSH) levels, were determined. In addition to the oxidative stress response, antioxidant enzyme activities including that of superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase were measured. Exposure to As elicited a significant increase in As concentration and significant modifications to the redox state of the kidney, as was evidenced by a significant elevation in LPO and nitrite/nitrate concentration, with a concomitant reduction in GSH content and antioxidant enzyme activity. The oxidant/antioxidant imbalance observed in As toxicity was associated with a significant elevation in renal tumor necrosis factor α, interleukin 6, B-cell lymphoma 2 (Bcl-2)-associated X protein, and caspase 3 levels, in addition to a significant decrease in Bcl-2 levels. Post-administration of TQ and Eb markedly prevented As-induced oxidative stress, inflammation, apoptosis, and As accumulation in the renal tissue and reduced histological renal damage. These findings demonstrate that TQ, the main bioactive phytochemical constituent of Nigella sativa seed oil, and Eb, an organoselenium compound, could significantly inhibit As-induced oxidative damage, apoptosis, and inflammation, and significantly attenuate the accumulation of As in renal tissues by facilitating As biomethylation and excretion.

Early-life arsenic exposure promotes atherogenic lipid metabolism in adolescence: A 15-year birth cohort follow-up study in central Taiwan

BACKGROUND

Inorganic arsenic (iAs) exposure potentially causes diabetes and cardiovascular diseases in adults. However, its effect on glucose and lipid metabolism in early life remains unknown.

OBJECTIVE

We evaluated the associations between early-life arsenic exposure and profiles of glucose and lipids in a 15-year birth cohort in central Taiwan.

METHODS

We studied 237 adolescents through 5 waves of follow-up interviews and examinations at ages of approximately 2, 5, 8, 11, and 14 y. We obtained at least one follow-up urine measurement for arsenic species and blood sample collection up to 14 y of age and identified group-based trajectories of serial iAs by semiparametric mixture modeling. Multiple linear and logistic regressions were performed to assess the effect of the arsenic exposure trajectory on serum fasting glucose, total cholesterol (TCHO), triglycerides (TGs), low-density lipoprotein cholesterol (LDL), and high-density lipoprotein cholesterol (HDL).

RESULTS

Three trajectories of postnatal arsenic exposure were identified, namely stable-low (31.4%), stable-high (48.2%), and rising-high (20.4%) groups. Compared with the stable-low trajectory group, the percent changes in TCHO and LDL was 14% (95% confidence interval 4-24%) and 23% (9-38%) for the group with "rising-high" trajectory and was 8% (-1-16%) and 16% (4-29%) for the group with "stable-high" trajectory. The rising-high group was also associated with an increase in the TCHO/HDL ratio by 14% (95% CI 3%-25%). The adjusted odds ratios of high developmental trajectories of TCHO, TG, LDL, and non-HDL levels were 4.0 (95% CI 1.2-13.7), 12.2 (2.2-67), 7.3 (1.8-30), and 3.6 (0.9-14.6), respectively, in the rising-high group (reference: stable-low group).

CONCLUSION

Our findings suggest that conversion to an atherogenic lipid profile in adolescents may be associated with early-life exposure to environmental arsenic, particularly during the pre-adolescent period. An environmental modification approach for preventing As-related cardiovascular disease is recommended to begin early in life.

Changes in Serum Adiponectin in Mice Chronically Exposed to Inorganic Arsenic in Drinking Water

Cardiovascular disease and diabetes mellitus are prominent features of glucose and lipid metabolism disorders. Adiponectin is a key adipokine that is largely involved in glucose and lipid metabolism processes. A growing body of evidence suggests that chronic exposure to inorganic arsenic is associated with cardiovascular disease and diabetes mellitus. We hypothesized that arsenic exposure may increase the risk of cardiovascular disease and diabetes mellitus by affecting the level of adiponectin. In this study, we examined serum adiponectin levels, as well as serum levels of metabolic measures (including fasting blood glucose, insulin, total cholesterol, triglyceride, and high-density lipoprotein (HDL)-cholesterol) in C57BL/6 mice exposed to inorganic arsenic in drinking water (5 and 50 ppm NaAsO₂) for 18 weeks. Body mass and adiposity were monitored throughout the study. We found no significant changes in serum insulin and glucose levels in mice treated with arsenic for 18 weeks. However, arsenic exposure decreased serum levels of adiponectin, triglyceride, and HDL-cholesterol. Further, an inverse relationship was observed between urinary concentrations of total arsenic and serum levels of adiponectin. This study suggests that arsenic exposure could disturb the metabolism of lipids and increase the risk of cardiovascular disease by reducing the level of adiponectin.

Heavy metal burdens of public primary school children related to playground soils and classroom dusts in Ibadan North-West local government area, Nigeria

Information about heavy metal burden of children in Nigeria related to playground soils and classroom dusts is lacking. Playground soil, classroom dust, blood and spot urine samples (n=253) were collected from 6 urban and 2 semi-rural public schools in Ibadan North-West, Nigeria. Samples were analysed for Pb, Cu, Zn, Fe and Mn. Mean blood Pb levels in urban area (male, 41.66±8.78μg/dl vs. female, 40.64±5.46μg/dl) were twice as high as those in semi-rural area (male, 19.71±3.73μg/dl vs. female, 20.65±2.26μg/dl). Concentrations of Pb, Cu, Zn, and Fe in soil and dust samples in the urban schools were between 2- to 4-fold greater than that of semi-rural schools. No correlation was observed between blood and dust metals. A positive correlation (r=0.168, p=0.008) was observed between blood Pb and playground soil Pb. Pb burden in the children might be from their schools' playgrounds and other yet unidentified sources.