Effects of arsenic exposure and genetic polymorphisms of p53, glutathione S-transferase M1, T1, and P1 on the risk of carotid atherosclerosis in Taiwan

Essential and Non-Essential Metals and Metalloids and Their Role in Atherosclerosis

Peripheral arterial disease (PAD) is becoming more prevalent in the aging developed world and can have significant functional impacts on patients. There is a recent recognition that environmental toxicants such as circulating metals and metalloids may contribute to the pathogenesis of atherosclerotic disease, but the mechanisms are complex. While the broad toxic biologic effects of metals in human systems have been extensively reviewed, the role of non-essential exposure and essential metal aberrancy in PAD specifically is less frequently discussed. This review of the literature describes current scientific knowledge regarding the individual roles several major metals and metalloids play in atherogenesis and highlights areas where a dearth of data exist. The roles of lead (Pb), arsenic (As), cadmium (Cd), iron (Fe), copper (Cu), selenium (Se) are included. Contemporary outcomes of therapeutic trials aimed at chelation therapy of circulating metals to impact cardiovascular outcomes are also discussed. This review highlights the supported notion of differential metal presence within peripheral plaques themselves, although distinguishing their roles within these plaques requires further illumination.

The links between soil and water pollution and cardiovascular disease

Soil and water pollution represent significant threats to global health, ecosystems, and biodiversity. Healthy soils underpin terrestrial ecosystems, supporting food production, biodiversity, water retention, and carbon sequestration. However, soil degradation jeopardizes the health of 3.2 billion people, while over 2 billion live in water-stressed regions. Pollution of soil, air, and water is a leading environmental cause of disease, contributing to over 9 million premature deaths annually. Soil contamination stems from heavy metals, synthetic chemicals, pesticides, and plastics, driven by industrial activity, agriculture, and waste mismanagement. These pollutants induce oxidative stress, inflammation, and hormonal disruption, significantly increasing risks for non-communicable diseases (NCDs) such as cardiovascular disease (CVD). Emerging contaminants like micro- and nanoplastics amplify health risks through cellular damage, oxidative stress, and cardiovascular dysfunction. Urbanization and climate change exacerbate soil degradation through deforestation, overfertilization, and pollution, further threatening ecosystem sustainability and human health. Mitigation efforts, such as reducing chemical exposure, adopting sustainable land-use practices, and advancing urban planning, have shown promise in lowering pollution-related health impacts. Public health initiatives, stricter pollution controls, and lifestyle interventions, including antioxidant-rich diets, can also mitigate risks. Pollution remains preventable, as demonstrated by high-income nations implementing cost-effective solutions. Policies like the European Commission's Zero-Pollution Vision aim to reduce pollution to safe levels by 2050, promoting sustainable ecosystems and public health. Addressing soil pollution is critical to combating the global burden of NCDs, particularly CVDs, and fostering a healthier environment for future generations.

The effect of consuming bread contaminated with heavy metals on cardiovascular disease and calculating its risk assessment

Heavy metals (HMs) may cause the generation of reactive oxygen species (ROS), which results in oxidative stress and eventually leads to an increase in cardiovascular diseases (CVD). The Hoveyzeh Cohort Study Center provided clinical data for cardiovascular cases. The collection of samples was done randomly. The association between CVD and HMs has been evaluated utilizing seven machine-learning techniques. The results showed that the effect coefficient (β) of bread consumption in the incidence of heart disease is 4.6908 × 10-02. Consumption of bread contaminated with chromium (P value < 0.0217), cadmium (P value < 2.95 × 10-6) and arsenic (P value < 1.15 × 10-07) is significantly related to cardiovascular incidence. Each unit of bread consumption increases As intake by 0.494 (β = 4.940 × 10-01) and CVD incidence by 11.9% (OR = 1.1190). Bread consumption increases Cd intake by 0.479 (β = 4.799 × 10-1) and cardiovascular disease incidence by 11.97% (OR = 1.1197) per unit. The findings indicated that bread intake in the study region is not correlated with non-carcinogenic or carcinogenic risks, since the cancer risk and incremental lifetime cancer risk for both groups were below 1*10^-6. In the present investigation, bread had HMs included As, Cd, Cr, and Pb higher than the limit declared by WHO. The results of the present study showed that bread is a mediating factor (between HMs and the incidence of CVD).

Carcinogenic and non-carcinogenic risks caused by rice contamination with heavy metals and their effect on the prevalence of cardiovascular disease (Using machine learning)

INTRODUCTION

The safety and health of food products are essential in the food industry, and the risk of contamination from various contaminants must be evaluated. Exposure to HMs from the environment (especially food) causes various adverse effects on the body and increases the risk of cardiovascular disease (CVD).

MATERIAL AND METHOD

Volunteers in the study comprised both healthy individuals and those with CVD. Patients were chosen using a cohort database of CVD individuals. A random choice of samples was conducted. Medical information (individuals with CVD) related to the participants was obtained from the Hoveyzeh Cohort Study Center. CVD-HM relationships were assessed using various machine-learning techniques.

RESULT

Based on the results of the GAM statistics approach, the baseline levels (β) of As, Cd, and Cr in rice have been calculated to be 1.05, 1.19, and 1.11, respectively. Based on the investigation's results, rice acts as a mediator between high-magnitude actions and the prevalence of CVD. Eating rice increases the probability of CVD by 0.18 and raises As eating by 0.494. The results showed that rice consumption in the research area is not associated with non-carcinogenic and carcinogenic risk (CRs and ILCRs for both categories were less than 1∗10-6).

CONCLUSION

There was neither a carcinogenic nor non-carcinogenic threat to adults or children and many hazardous HMs existed at the accepted thresholds. A notable relationship was seen between rice contaminated with HM and CVD.

Update of the risk assessment of inorganic arsenic in food

The European Commission asked EFSA to update its 2009 risk assessment on arsenic in food carrying out a hazard assessment of inorganic arsenic (iAs) and using the revised exposure assessment issued by EFSA in 2021. Epidemiological studies show that the chronic intake of iAs via diet and/or drinking water is associated with increased risk of several adverse outcomes including cancers of the skin, bladder and lung. The CONTAM Panel used the benchmark dose lower confidence limit based on a benchmark response (BMR) of 5% (relative increase of the background incidence after adjustment for confounders, BMDL05) of 0.06 μg iAs/kg bw per day obtained from a study on skin cancer as a Reference Point (RP). Inorganic As is a genotoxic carcinogen with additional epigenetic effects and the CONTAM Panel applied a margin of exposure (MOE) approach for the risk characterisation. In adults, the MOEs are low (range between 2 and 0.4 for mean consumers and between 0.9 and 0.2 at the 95th percentile exposure, respectively) and as such raise a health concern despite the uncertainties.

A Clinical Perspective on Arsenic Exposure and Development of Atherosclerotic Cardiovascular Disease

Cardiovascular risk has traditionally been defined by modifiable and non-modifiable risk factors, such as tobacco use, hyperlipidemia, and family history. However, chemicals and pollutants may also play a role in cardiovascular disease (CVD) risk. Arsenic is a naturally occurring element that is widely distributed in the Earth's crust. Inorganic arsenic (iAs) has been implicated in the pathogenesis of atherosclerosis, with chronic high-dose exposure to iAs (> 100 µg/L) being linked to CVD; however, whether low-to-moderate dose exposures of iAs (< 100 µg/L) are associated with the development of CVD is unclear. Due to limitations of the existing literature, it is difficult to define a threshold for iAs toxicity. Studies demonstrate that the effect of iAs on CVD is far more complex with influences from several factors, including diet, genetics, metabolism, and traditional risk factors such as hypertension and smoking. In this article, we review the existing data of low-to-moderate dose iAs exposure and its effect on CVD, along with highlighting the potential mechanisms of action.

Contaminant Metals and Cardiovascular Health

A growing body of research has begun to link exposure to environmental contaminants, such as heavy metals, with a variety of negative health outcomes. In this paper, we sought to review the current research describing the impact of certain common contaminant metals on cardiovascular (CV) health. We reviewed ten metals: lead, barium, nickel, chromium, cadmium, arsenic, mercury, selenium, zinc, and copper. After a literature review, we briefly summarized the routes of environmental exposure, pathophysiological mechanisms, CV health impacts, and exposure prevention and/or mitigation strategies for each metal. The resulting article discloses a broad spectrum of pathological significance, from relatively benign substances with little to no described effects on CV health, such as chromium and selenium, to substances with a wide-ranging and relatively severe spectrum of CV pathologies, such as arsenic, cadmium, and lead. It is our hope that this article will provide clinicians with a practical overview of the impact of these common environmental contaminants on CV health as well as highlight areas that require further investigation to better understand how these metals impact the incidence and progression of CV diseases.

Co-exposure to arsenic and fluoride to explore the interactive effect on oxidative stress and autophagy in myocardial tissue and cell

Co-contamination of arsenic and fluoride is widely distributed in groundwater. However, little is known about the interactively influence of arsenic and fluoride, especially the combined mechanism in cardiotoxicity. Cellular and animal models exposure to arsenic and fluoride were established to assess the oxidative stress and autophagy mechanism of cardiotoxic damage using the factorial design, a widely used statistical method for assessing two factor interventions. In vivo, combined exposure to high arsenic (50 mg/L) and high fluoride (100 mg/L) induced myocardial injury. The damage is accompanied by accumulation of myocardial enzyme, mitochondrial disorder, and excessive oxidative stress. Further experiment identified that arsenic and fluoride induced the accumulation of autophagosome and increased expression level of autophagy related genes during the cardiotoxicity process. These findings were further demonstrated through the in vitro model of arsenic and fluoride-treated the H9c2 cells. Additionally, combined of arsenic-fluoride exposure possesses the interactively influence on oxidative stress and autophagy, contributing to the myocardial cell toxicity. In conclusion, our data suggest that oxidative stress and autophagy are involved in the process of cardiotoxic injury, and that these indicators showed interaction effect in response to the combined exposure of arsenic and fluoride.

Glutathione S-Transferase P1 Genetic Variant's Influence on the HbA1c Level in Type Two Diabetic Patients

GST (glutathione S-transferases) are capable of influencing glucose homeostasis, probably through regulation of the response to oxidant stress. The aim of our study was to investigate the relationship between GSTP1 gene polymorphism and glycated hemoglobin (HbA1c) levels in type two diabetic (T2D) patients. A total of 307 T2D patients were included. Analysis of the GSTP1 gene polymorphism (rs1695) was conducted using the TaqMan qPCR method endpoint genotyping. HbA1c was determined using a COBAS 6000 autoanalyzer. A univariable linear regression and multivariable linear regression model were used to investigate the association between mean HbA1c level and GSTP1 gene polymorphism, age at T2D diagnosis, T2D duration, therapy with insulin, gender, BMI, smoking status. GSTP1 Val/Val genotype, age at T2D diagnosis, T2D duration and therapy with insulin were statistically significant contributors to HbA1c levels (p < 0.05). Multivariable regression analysis revealed that GSTP1 (Val/Val vs. Ile/Ile) was associated with higher HbA1c even after adjustment for variables that showed a statistically significant relationship with HbA1c in univariable analyses (p = 0.024). The results suggest that GSTP polymorphism may be one of the risk factors for higher HbA1c in T2D patients. Our study is limited by the relatively small sample size, cross-sectional design, and lack of inclusion of other oxidative stress-related genetic variants.

Drinking water and the implications for gender equity and empowerment: A systematic review of qualitative and quantitative evidence

BACKGROUND

Safe drinking water is a fundamental human right, yet more than 785 million people do not have access to it. The burden of water management disproportionately falls on women and young girls, and they suffer the health, psychosocial, political, educational, and economic effects. While water conditions and disease outcomes have been widely studied, few studies have summarized the research on drinking water and implications for gender equity and empowerment (GEE).

METHODS

A systematic review of primary literature published between 1980 and 2019 was conducted on drinking water exposures and management and the implications for GEE. Ten databases were utilized (EMBASE, PubMed, Web of Science, Cochrane, ProQuest, Campbell, the British Library for Development Studies, SSRN, 3ie International Initiative for Impact Evaluation, and clinicaltrials.gov). Drinking water studies with an all-female cohort or disaggregated findings according to gender were included.

RESULTS

A total of 1280 studies were included. GEE outcomes were summarized in five areas: health, psychosocial stress, political power and decision-making, social-educational conditions, and economic and time-use conditions. Water quality exposures and implications for women's health dominated the literature reviewed. Women experienced higher rates of bladder cancer when exposed to arsenic, trihalomethanes, and chlorine in drinking water and higher rates of breast cancer due to arsenic, trichloroethylene, and disinfection byproducts in drinking water, compared to men. Women that were exposed to arsenic experienced higher incidence rates of anemia and adverse pregnancy outcomes compared to those that were not exposed. Water-related skin diseases were associated with increased levels of psychosocial stress and social ostracization among women. Women had fewer decision-making responsibilities, economic independence, and employment opportunities around water compared to men.

CONCLUSION

This systematic review confirms the interconnected nature of gender and WaSH outcomes. With growing attention directed towards gender equity and empowerment within WaSH, this analysis provides key insights to inform future research and policy.

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.

Association of GSTP1 Ile105Val polymorphism with the risk of coronary heart disease: An updated meta-analysis

Background

Numerous case-control studies have investigated the association between GSTP1 Ile105Val polymorphism and CHD risk, but the results from published studies were inconclusive. The present meta-analysis was performed to derive a more precise estimation.

Methods

PubMed, EMBASE, and Web of Science database searches were conducted to retrieve relevant articles.

Results

Ultimately, 5,451 CHD cases and 5,561 controls from 15 studies were included. Pooled analysis did not yield any statistically significant association between GSTP1 Ile105Val polymorphism and CHD risk for the overall population (Val vs. Ile: OR, 1.05; 95% CI, 0.93 to 1.18; Val/Val vs. Ile/Ile: OR, 1.09; 95% CI, 0.83 to 1.42; Val/Ile vs. Ile/Ile: OR, 1.09; 95% CI, 0.93 to 1.28; Val/Val vs. Val/Ile+Ile/Ile: OR, 1.04; 95% CI, 0.83 to 1.30; Val/Val+Val/Ile vs. Ile/Ile: OR, 1.14; 95% CI, 0.97 to 1.33). Subgroup analyses and sensitivity analyses indicated that GSTP1 Ile105Val polymorphism was still not associated with an increased risk of CHD. After excluding studies detected by Galbraith plots as major sources of heterogeneity, these relationships were still not significant.

Conclusions

The overall results did not reveal a major role of the GSTP1 Ile105Val polymorphism in modulating CHD risk. Well-designed studies with large sample sizes are needed to validate our findings and explore the possible gene-gene or gene-environment interactions.

Use of study-specific MOE-like estimates to prioritize health effects from chemical exposure for analysis in human health assessments

There are unique challenges in estimating dose-response with chemicals that are associated with multiple health outcomes and numerous studies. Some studies are more suitable than others for quantitative dose-response analyses. For such chemicals, an efficient method of screening studies and endpoints to identify suitable studies and potentially important health effects for dose-response modeling is valuable. Using inorganic arsenic as a test case, we developed a tiered approach that involves estimating study-specific margin of exposure (MOE)-like unitless ratios for two hypothetical scenarios. These study-specific unitless ratios are derived by dividing the exposure estimated to result in a 20% increase in relative risk over the background exposure (RRE20) by the background exposure, as estimated in two different ways. In our case study illustration, separate study-specific ratios are derived using estimates of United States population background exposure (RRB-US) and the mean study population reference group background exposure (RRB-SP). Systematic review methods were used to identify and evaluate epidemiologic studies, which were categorized based on study design (case-control, cohort, cross-sectional), various study quality criteria specific to dose-response analysis (number of dose groups, exposure ascertainment, exposure uncertainty), and availability of necessary dose-response data. Both case-control and cohort studies were included in the RRB analysis. The RRE20 estimates were derived by modeling effective counts of cases and controls estimated from study-reported adjusted odds ratios and relative risks. Using a broad (but not necessarily comprehensive) set of epidemiologic studies of multiple health outcomes selected for the purposes of illustrating the RRB approach, this test case analysis would suggest that diseases of the circulatory system, bladder cancer, and lung cancer may be arsenic health outcomes that warrant further analysis. This is suggested by the number of datasets from adequate dose-response studies demonstrating an effect with RRBs close to 1 (i.e., RRE20 values close to estimated background arsenic exposure levels).

Individual susceptibility to arsenic-induced diseases: the role of host genetics, nutritional status, and the gut microbiome

Arsenic (As) contamination in water or food is a global issue affecting hundreds of millions of people. Although As is classified as a group 1 carcinogen and is associated with multiple diseases, the individual susceptibility to As-related diseases is highly variable, such that a proportion of people exposed to As have higher risks of developing related disorders. Many factors have been found to be associated with As susceptibility. One of the main sources of the variability found in As susceptibility is the variation in the host genome, namely, polymorphisms of many genes involved in As transportation, biotransformation, oxidative stress response, and DNA repair affect the susceptibility of an individual to As toxicity and then influence the disease outcomes. In addition, lifestyles and many nutritional factors, such as folate, vitamin C, and fruit, have been found to be associated with individual susceptibility to As-related diseases. Recently, the interactions between As exposure and the gut microbiome have been of particular concern. As exposure has been shown to perturb gut microbiome composition, and the gut microbiota has been shown to also influence As metabolism, which raises the question of whether the highly diverse gut microbiota contributes to As susceptibility. Here, we review the literature and summarize the factors, such as host genetics and nutritional status, that influence As susceptibility, and we also present potential mechanisms of how the gut microbiome may influence As metabolism and its toxic effects on the host to induce variations in As susceptibility. Challenges and future directions are also discussed to emphasize the importance of characterizing the specific role of these factors in interindividual susceptibility to As-related diseases.

Association between arsenic exposure and soluble thrombomodulin: A cross sectional study in Bangladesh

Chronic exposure to arsenic is associated with increased morbidity and mortality from cardiovascular disease (CVD); however, plausible biomarker for early prediction and the underlying mechanism of arsenic-related CVD have not yet been clearly understood. Endothelial dysfunction plays a central role in the development of CVD. We hypothesized that endothelial damage or dysfunction is an important aspect and may be an early event of arsenic-related CVD. Soluble thrombomodulin (sTM) in serum is thought to be a specific and stable marker for endothelial damage or dysfunction. This study was designed to evaluate the association between chronic exposure to arsenic and sTM among human subjects in arsenic-endemic and non-endemic rural areas in Bangladesh. A total of 321 study subjects (217 from arsenic-endemic areas and 104 from a non-endemic area) were recruited. Subjects' arsenic exposure levels (i.e., drinking water, hair and nail arsenic concentrations) were measured by Inductively Coupled Plasma Mass Spectroscopy. The subjects' serum sTM levels were quantified by immunoassay kit. The average sTM levels of the subjects in arsenic-endemic and non-endemic areas were 4.58 ± 2.20 and 2.84 ± 1.29 (ng mL-1) respectively, and the difference was significant (p<0.001). Arsenic exposure levels showed a significant (water arsenic: rs = 0.339, p<0.001, hair arsenic: rs = 0.352, p<0.001 and nail arsenic: rs = 0.308, p<0.001) positive associations with sTM levels. Soluble TM levels were higher in the higher exposure gradients if we stratified the subjects into tertile groups (low, medium and high) based on the arsenic concentrations of the subjects' drinking water, hair and nails. Finally, increased levels of sTM were negatively correlated with high density lipoprotein cholesterol (HDL-C), and positively correlated with intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1). Results of this study show that chronic exposure to arsenic has mild to moderate association with sTM levels.

Arsenic Exposure and Predicted 10-Year Atherosclerotic Cardiovascular Risk Using the Pooled Cohort Equations in U.S. Hypertensive Adults

This study was to evaluate the association of urine arsenic with predicted 10-year atherosclerotic cardiovascular disease (ASCVD) risk in U.S. adults with hypertension. Cross-sectional analysis was conducted in 1570 hypertensive adults aged 40-79 years in the 2003-2012 National Health and Nutrition Examination Survey (NHANES) with determinations of urine arsenic. Predicted 10-year ASCVD risk was estimated by the Pooled Cohort Equations, developed by the American College of Cardiology/American Heart Association in 2013. For men, after adjustment for sociodemographic factors, urine dilution, ASCVD risk factors and organic arsenic intake from seafood, participants in the highest quartiles of urine arsenic had higher 10-year predicted ASCVD risk than in the lowest quartiles; the increases were 24% (95% confidence interval (CI): 2%, 53%) for total arsenic, 13% (95% CI: 2%, 25%) for dimethylarsinate and 22% (95% CI: 5%, 40%) for total arsenic minus arsenobetaine separately. For women, the corresponding increases were 5% (95% CI: -15%, 29%), 10% (95% CI: -8%, 30%) and 0% (95% CI: -15%, 19%), respectively. Arsenic exposure, even at low levels, may contribute to increased ASCVD risk in men with hypertension. Furthermore, our findings suggest that particular circumstances need urgently to be considered while elucidating cardiovascular effects of low inorganic arsenic levels.

Arsenic and subclinical vascular damage in a sample of Italian young adults: a cross-sectional analysis

Exposure to arsenic (As) increases cardiovascular risk. The purpose of this study was to evaluate the relationship between As and intima-media thickness (IMT) in the common carotid artery and common genetic variants in genes implicated in As metabolism (ASIIIMT Met287Thr, GSTT1+/-, and GSTM1+/-) and DNA repair (hOGG1 Ser326Cys and XRCC1 Arg399Ser). Two hundred and fourteen healthy volunteers, age 20-46, were recruited in four zones polluted by As. Urine samples were tested for total As, inorganic As (iAs), monomethylarsinic (MMA), and dimethylarsinic acid (DMA). Primary and secondary methylation index (PMI, SMI) were computed as MMA/iAs and DMA/MMA. Common carotid artery scans were obtained by high-resolution ultrasound. There was no correlation between IMT and total As, iAs, iAs + MMA + DMA, PMI, or SMI. However, the increase of IMT with age was higher than that observed in the healthy population, both in males (6.25 vs. 5.20 μm/year) and, to a lesser extent, in females (5.05 vs. 4.97 μm/year). After correction for age and gender, subjects with a high urinary As level (≥3.86 μg/L) and carriers of the GSTT1-positive (+) genotype also had higher IMT than those with a low urinary level and the GSTT1-null (-) genotype (0.56 [0.48-0.64] vs. 0.53 [0.44-0.62] mm, p = 0.010). The analysis hints at faster vascular aging as compared to the healthy population. Our findings also suggested that GSTT1 and hOGG1 gene polymorphisms might play an important role in the individual risk of As-induced carotid atherosclerosis.

Effect of heme oxygenase-1 gene promoter polymorphism on cancer risk by histological subtype: A prospective study in arseniasis-endemic areas in Taiwan

Heme oxygenase (HO)-1 is upregulated by many stressful stimuli, including arsenic. A GT-repeat ((GT)n) polymorphism in the HO-1 gene promoter inversely modulates the levels of HO-1 induction. Previous HO-1 (GT)n polymorphism studies in relation to cancer risk have shown disparate results. We prospectively investigated the associations between HO-1 (GT)n polymorphism and cancer risk related to arsenic from drinking water. Totally, 1,013 participants from community-based cohorts of arseniasis-endemic areas in Taiwan were followed for 13 years. Allelic polymorphisms were classified into long (L, ≥ 27 (GT)n) and short (S, <27 (GT)n). Newly developed cases were identified through linkage with National Cancer Registry of Taiwan. Multivariate Cox proportional hazard methods were used to evaluate effects of the HO-1 polymorphism alone or combined with arsenic exposure. Results showed that participants with the S/S genotype had an increased risk of Bowen's disease (HR = 10.49; 95% CI: 2.77-39.7), invasive skin cancer (HR = 2.99; 95% CI: 1.13-7.87), and lung squamous cell carcinoma (HR = 3.39; 95% CI: 1.15-9.95) versus those with L/S or L/L genotype. The S/S genotype combined with high arsenic exposure (>300 μg/L) had a greater risk of skin cancer compared to the genotype alone. Consistent with previous findings, participants with the S-allele had a reduced risk of lung adenocarcinoma (HR = 0.21; 95% CI: 0.03-0.68) versus those with L/L genotype. There were no significant differences in risk of urothelial carcinoma among the three genotypes. Associations of HO-1 (GT)n polymorphism with cancer risk differs by histological subtype and the polymorphism should be considered a modifier in the risk assessment of arsenic exposure.

Influence of MRP1 G1666A and GSTP1 Ile105Val genetic variants on the urinary and blood arsenic levels of Turkish smelter workers

To understand the cellular mechanisms responsible for arsenic metabolism and transport pathways plays a fundamental role in order to prevent the arsenic-induced toxicity. The effect of MRP1 G1666A and GSTP1 Ile105Val polymorphisms on blood and urinary arsenic levels were determined in 95 Turkish smelter workers. Blood and urinary arsenic concentrations were measured by GF-AAS with Zeeman correction and gene polymorphisms were investigated by PCR-RFLP method. The mean blood and urinary arsenic levels were 21.60±12.28μg/L and 5.58±4.37μg/L, respectively. A significant association between MRP1 1666A allele and urinary arsenic levels was found (p=0.001). GSTP1 Ile105Val polymorphism was detected not to be associated with either blood or urinary arsenic levels (p=0.384, p=0.440, respectively). Significant association was also detected between MRP1A(-)/GSTP1Val(-) genotypes and urinary arsenic levels (p=0.001). This study suggested that MRP1 G1666A alone and, also, combined with GSTP1 Ile105Val were associated with inter-individual variations in urinary arsenic levels, but not with blood arsenic levels.

Glutathione-S-Transferase Variants are not Associated With Increased Carotid Intima-Media Thickness in Turkish Familial Mediterranean Fever Patients

Objectives

This study aims to evaluate the carotid intima-media thickness (CIMT) in patients diagnosed with Familial Mediterranean fever (FMF) and investigate whether there is a relationship between glutathione-S-transferase (GST) gene polymorphisms and CIMT.

Patients and methods

Sixty FMF patients (17 males, 43 females; mean age: 31.43±11.36 years; range 18 to 45 years) and 60 healthy controls (22 males, 38 females; mean age: 29.8±5.82 years; range 18 to 40 years) were enrolled in this study. Polymerase chain reaction-restriction fragment length polymorphism methods were carried out to assess GST polymorphisms. CIMT was measured by carotid ultrasonography. Biochemical parameters were also evaluated using biochemical methods.

Results

Right and left CIMT of FMF patients were statistically significantly higher than that of control group (CIMT right p=0.001 and CIMT left: p=0.033). There was no significant association in terms of GST polymorphisms between FMF and control groups. No significant association was observed between GST polymorphisms and CIMT. Low density lipoprotein, erythrocyte sedimentation rate, and fibrinogen levels were significantly higher in the patient group (p<0.05). The difference between groups was not significant in terms of other biochemical parameters (p>0.05).

Conclusion

Although no significant association was observed between GST polymorphisms and CIMT in FMF patients and controls, CIMT was statistically significantly higher in FMF patients compared to controls.

Arsenic and human health effects: A review

Arsenic (As) is ubiquitous in nature and humans being exposed to arsenic via atmospheric air, ground water and food sources are certain. Major sources of arsenic contamination could be either through geological or via anthropogenic activities. In physiological individuals, organ system is described as group of organs that transact collectively and associate with other systems for conventional body functions. Arsenic has been associated with persuading a variety of complications in body organ systems: integumentary, nervous, respiratory, cardiovascular, hematopoietic, immune, endocrine, hepatic, renal, reproductive system and development. In this review, we outline the effects of arsenic on the human body with a main focus on assorted organ systems with respective disease conditions. Additionally, underlying mechanisms of disease development in each organ system due to arsenic have also been explored. Strikingly, arsenic has been able to induce epigenetic changes (in utero) and genetic mutations (a leading cause of cancer) in the body. Occurrence of various arsenic induced health effects involving emerging areas such as epigenetics and cancer along with their respective mechanisms are also briefly discussed.

Environmental factors in cardiovascular disease

Environmental exposure is an important but underappreciated risk factor contributing to the development and severity of cardiovascular disease (CVD). The heart and vascular system are highly vulnerable to a number of environmental agents--ambient air pollution and the metals arsenic, cadmium, and lead are widespread and the most-extensively studied. Like traditional risk factors, such as smoking and diabetes mellitus, these exposures advance disease and mortality via augmentation or initiation of pathophysiological processes associated with CVD, including blood-pressure control, carbohydrate and lipid metabolism, vascular function, and atherogenesis. Although residence in highly polluted areas is associated with high levels of cardiovascular risk, adverse effects on cardiovascular health also occur at exposure levels below current regulatory standards. Considering the widespread prevalence of exposure, even modest contributions to CVD risk can have a substantial effect on population health. Evidence-based clinical and public-health strategies aimed at reducing environmental exposures from current levels could substantially lower the burden of CVD-related death and disability worldwide.

Low-level arsenic exposure and developmental neurotoxicity in children: A systematic review and risk assessment

Risk assessments of arsenic have focused on skin, bladder, and lung cancers and skin lesions as the sensitive cancer and non-cancer health endpoints, respectively; however, an increasing number of epidemiologic studies that can inform risk assessment have examined neurodevelopmental effects in children. We conducted a systematic review and risk assessment based on the epidemiologic literature on possible neurodevelopmental effects at lower arsenic exposures. Twenty-four cross-sectional, case-control, and cohort studies were identified that report on the association between low-level arsenic exposure (i.e., largely <100 μg/L of arsenic in drinking water) and neurological outcomes in children. Although the overall evidence does not consistently show a causal dose-response relationship at low doses, the most rigorously conducted studies from Bangladesh indicate possible inverse associations with cognitive function, predominantly involving concurrent arsenic exposure as measured by biomarkers (i.e., arsenic in urine or blood) and raw verbal test scores at ages 5-11 years. Issues such as non-comparability of outcome measures across studies; inaccuracies of biomarkers and other measures of inorganic arsenic exposure; potential effect modification by cultural practices; insufficient adjustment for nutritional deficiencies, maternal IQ, and other important confounders; and presence of other neurotoxicants in foreign populations limit generalizability to U.S.

POPULATIONS

Of the few U.S. studies available, the most rigorously conducted study did not find a consistent dose-response relationship between arsenic concentrations in tap water or toenails and decrements in IQ scores. Assuming that the strongest dose-response relationship from the most rigorous evidence from Bangladesh is generalizable to U.S. populations, possible reference doses were estimated in the range of 0.0004-0.001 mg/kg-day. These doses are higher than the U.S. Environmental Protection Agency reference dose for chronic lifetime exposure, thus indicating protectiveness of the existing value for potential neurotoxicity in children. This reference dose is undergoing revision as EPA considers various health endpoints in the reassessment of inorganic arsenic health risks.

Interaction between arsenic exposure from drinking water and genetic polymorphisms on cardiovascular disease in Bangladesh: a prospective case-cohort study

BACKGROUND

Epidemiologic data on genetic susceptibility to cardiovascular effects of arsenic exposure from drinking water are limited.

OBJECTIVE

We investigated whether the association between well-water arsenic and cardiovascular disease (CVD) differed by 170 single nucleotide polymorphisms (SNPs) in 17 genes related to arsenic metabolism, oxidative stress, inflammation, and endothelial dysfunction.

METHOD

We conducted a prospective case-cohort study nested in the Health Effects of Arsenic Longitudinal Study, with a random subcohort of 1,375 subjects and 447 incident fatal and nonfatal cases of CVD. Well-water arsenic was measured in 2000 at baseline. The CVD cases, 56 of which occurred in the subcohort, included 238 coronary heart disease cases, 165 stroke cases, and 44 deaths due to other CVD identified during follow-up from 2000 to 2012.

RESULTS

Of the 170 SNPs tested, multiplicative interactions between well-water arsenic and two SNPs, rs281432 in ICAM1 (padj = 0.0002) and rs3176867 in VCAM1 (padj = 0.035), were significant for CVD after adjustment for multiple testing. Compared with those with GC or CC genotype in rs281432 and lower well-water arsenic, the adjusted hazard ratio (aHR) for CVD was 1.82 (95% CI: 1.31, 2.54) for a 1-SD increase in well-water arsenic combined with the GG genotype, which was greater than expected given aHRs of 1.08 and 0.96 for separate effects of arsenic and the genotype alone, respectively. Similarly, the joint aHR for arsenic and the rs3176867 CC genotype was 1.34 (95% CI: 0.95, 1.87), greater than expected given aHRs for their separate effects of 1.02 and 0.84, respectively.

CONCLUSIONS

Associations between CVD and arsenic exposure may be modified by genetic variants related to endothelial dysfunction.

Mechanisms of action for arsenic in cardiovascular toxicity and implications for risk assessment

The possibility of an association between inorganic arsenic (iAs) exposure and cardiovascular outcomes has received increasing attention in the literature over the past decade. The United States Environmental Protection Agency (US EPA) is currently revising its Integrated Risk Assessment System (IRIS) review of iAs, and one of the non-cancer endpoints of interest is cardiovascular disease (CVD). Despite the increased interest in this area, substantial gaps remain in the available information, particularly regarding the mechanism of action (MOA) by which iAs could cause or exacerbate CVD. Few studies specifically address the plausibility of an association between iAs and CVD at the low exposure levels which are typical in the United States (i.e., below 100 μg As/L in drinking water). We have conducted a review and evaluation of the animal, mechanistic, and human data relevant to the potential MOAs of iAs and CVD. Specifically, we evaluated the most common proposed MOAs, which include disturbance of endothelial function and hepatic dysfunction. Our analysis of the available evidence indicates that there is not a well-established MOA for iAs in the development or progression of CVD. Few human studies of the potential MOAs have addressed plausibility at low doses and the applicability of extrapolation from animal studies to humans is questionable. However, the available evidence indicates that regardless of the specific MOA, the effects of iAs on physiological processes at the cellular level appear to operate via a threshold mechanism. This finding is consistent with the lack of association of CVD with iAs exposure in humans at levels below 100 μg/L, particularly when considering important exposure and risk modifiers such as nutrition and genetics. Based on this analysis, we conclude that there are no data supporting a linear dose-response relationship between iAs and CVD, indicating this relationship has a threshold.

Association of low-level arsenic exposure in drinking water with cardiovascular disease: a systematic review and risk assessment

The U.S. Environmental Protection Agency (EPA) is developing an integrated assessment of non-cancer and cancer risk assessment of inorganic arsenic (iAs). Cardiovascular disease (CVD) in association with iAs exposure has been examined in a number of studies and provides a basis for evaluating a reference dose (RfD) for assessing potential non-cancer health risks of arsenic exposure. In this systematic review of low-level iAs exposure (i.e., <100-150μg/L arsenic water concentration) and CVD in human populations, 13 cohort and case-control studies from the United States, Taiwan, Bangladesh, and China were identified and critically examined for evidence for derivation of a RfD. Eight cross-sectional and ecological studies from the United States were also examined for additional information. Prospective cohort data from Bangladesh provided the strongest evidence for determining the point of departure in establishing a candidate RfD based on a combined endpoint of mortality from "ischemic heart disease and other heart diseases." This study as well as the overall literature supported a no-observed-adverse-effect level of 100μg/L for arsenic in water, which was equivalent to an iAs dose of 0.009mg/kg-day (based on population-specific water consumption rates and dietary iAs intake). The study population was likely sensitive to arsenic toxicity because of nutritional deficiencies affecting arsenic methylation and one-carbon metabolism, as well as increasing CVD risk. Evidence is less clear on the interaction of CVD risk factors in the United States (e.g., diabetes, obesity, and hypertension) with arsenic at low doses. Potential uncertainty factors up to 3 resulted in a RfD for CVD in the range of 0.003-0.009mg/kg-day. Although caution should be exercised in extrapolating these results to the U.S. general population, these doses allow a margin of exposure that is 10-30 times the current RfD derived by EPA (based on skin lesions in Southwest Taiwan). These findings suggest that the current EPA RfD is protective of CVD.

A prospective study of arm circumference and risk of death in Bangladesh

BACKGROUND

Epidemiological studies have observed protective effects of mid-upper arm circumference (MUAC) against all-cause mortality mostly in Western populations. However, evidence on cause-specific mortality is limited.

METHODS

The sample included 19 575 adults from a population-based cohort study in rural Bangladesh, who were followed up for an average of 7.9 years for mortality. Cox proportional hazards regression was used to evaluate the effect of MUAC, as well as the joint effect of body mass index (BMI) and MUAC, on the risk of death from any cause, cancer and cardiovascular disease (CVD).

RESULTS

During 154 664 person-years of follow-up, 744 deaths including 312 deaths due to CVD and 125 deaths due to cancer were observed. There was a linear inverse relationship of MUAC with total and CVD mortality. Each 1-cm increase in MUAC was associated a reduced risk of death from any cause [hazard ratio (HR) = 0.85; 95% confidence interval (C), 0.81-0.89) and CVD (HR = 0.87; 95% CI, 0.80-0.94), after controlling for potential confounders. No apparent relationship between MUAC and the risk of death from cancer was observed. Among individuals with a low BMI (<18.5 kg/m(2)), a MUAC less than 24 cm was associated with increased risk for all-cause (HR = 1.81; 95% CI, 1.52-2.17) and CVD mortality (HR = 1.45; 95% CI, 1.11-1.91).

CONCLUSIONS

MUAC may play a critical role on all-cause and CVD mortality in lean Asians.

Arsenic Exposure and Subclinical Endpoints of Cardiovascular Diseases

Mechanistic evidence suggests that arsenic exposure from drinking water increases the production of reactive oxygen species and influences inflammatory responses and endothelial nitric oxide homeostasis. These arsenic-induced events may lead to endothelial dysfunction that increases the risk of atherosclerosis and cardiovascular disease. We reviewed accumulating epidemiologic evidence that evaluated the association between arsenic exposure and intermediate markers and subclinical measures that predict future cardiovascular risk. Cross-sectional studies have indicated positive associations between high or low-to-moderate levels of arsenic exposure with indices of subclinical atherosclerosis, QT interval prolongation, and circulating markers of endothelial dysfunction. The evidence is limited for other intermediate endpoints such as markers of oxidative stress and inflammation, QT dispersion, and lipid profiles. Prospective studies are needed to enhance the causal inferences of arsenic's effects on subclinical endpoints of cardiovascular disease, especially at lower arsenic exposure levels.

Interaction between arsenic exposure from drinking water and genetic susceptibility in carotid intima-media thickness in Bangladesh

Epidemiologic studies that evaluated genetic susceptibility for the effects of arsenic exposure from drinking water on subclinical atherosclerosis are limited. We conducted a cross-sectional study of 1078 participants randomly selected from the Health Effects of Arsenic Longitudinal Study in Bangladesh to evaluate whether the association between arsenic exposure and carotid artery intima-media thickness (cIMT) differs by 207 single-nucleotide polymorphisms (SNPs) in 18 genes related to arsenic metabolism, oxidative stress, inflammation, and endothelial dysfunction. Although not statistically significant after correcting for multiple testing, nine SNPs in APOE, AS3MT, PNP, and TNF genes had a nominally statistically significant interaction with well-water arsenic in cIMT. For instance, the joint presence of a higher level of well-water arsenic (≥ 40.4 μg/L) and the GG genotype of AS3MT rs3740392 was associated with a difference of 40.9 μm (95% CI = 14.4, 67.5) in cIMT, much greater than the difference of cIMT associated with the genotype alone (β = -5.1 μm, 95% CI = -31.6, 21.3) or arsenic exposure alone (β = 7.2 μm, 95% CI = -3.1, 17.5). The pattern and magnitude of the interactions were similar when urinary arsenic was used as the exposure variable. Additionally, the at-risk genotypes of the AS3MT SNPs were positively related to the proportion of monomethylarsonic acid (MMA) in urine, which is indicative of arsenic methylation capacity. The findings provide novel evidence that genetic variants related to arsenic metabolism may play an important role in arsenic-induced subclinical atherosclerosis. Future replication studies in diverse populations are needed to confirm the findings.

Molecular biology of atherosclerosis

At least 468 individual genes have been manipulated by molecular methods to study their effects on the initiation, promotion, and progression of atherosclerosis. Most clinicians and many investigators, even in related disciplines, find many of these genes and the related pathways entirely foreign. Medical schools generally do not attempt to incorporate the relevant molecular biology into their curriculum. A number of key signaling pathways are highly relevant to atherogenesis and are presented to provide a context for the gene manipulations summarized herein. The pathways include the following: the insulin receptor (and other receptor tyrosine kinases); Ras and MAPK activation; TNF-α and related family members leading to activation of NF-κB; effects of reactive oxygen species (ROS) on signaling; endothelial adaptations to flow including G protein-coupled receptor (GPCR) and integrin-related signaling; activation of endothelial and other cells by modified lipoproteins; purinergic signaling; control of leukocyte adhesion to endothelium, migration, and further activation; foam cell formation; and macrophage and vascular smooth muscle cell signaling related to proliferation, efferocytosis, and apoptosis. This review is intended primarily as an introduction to these key signaling pathways. They have become the focus of modern atherosclerosis research and will undoubtedly provide a rich resource for future innovation toward intervention and prevention of the number one cause of death in the modern world.

Arsenic exposure from drinking water, arsenic methylation capacity, and carotid intima-media thickness in Bangladesh

We conducted a cross-sectional study to evaluate the interrelationships between past arsenic exposure, biomarkers specific for susceptibility to arsenic exposure, and carotid intima-media thickness (cIMT) in 959 subjects from the Health Effects of Arsenic Longitudinal Study in Bangladesh. We measured cIMT levels on average 7.2 years after baseline during 2010-2011. Arsenic exposure was measured in well water at baseline and in urine samples collected at baseline and during follow-up. Every 1-standard-deviation increase in urinary arsenic (357.9 µg/g creatinine) and well-water arsenic (102.0 µg/L) concentration was related to a 11.7-µm (95% confidence interval (CI): 1.8, 21.6) and 5.1-µm (95% CI: -0.2, 10.3) increase in cIMT, respectively. For every 10% increase in monomethylarsonic acid (MMA) percentage, there was an increase of 12.1 µm (95% CI: 0.4, 23.8) in cIMT. Among participants with a higher urinary MMA percentage, a higher ratio of urinary MMA to inorganic arsenic, and a lower ratio of dimethylarsinic acid to MMA, the association between well-water arsenic and cIMT was stronger. The findings indicate an effect of past long-term arsenic exposure on cIMT, which may be potentiated by suboptimal or incomplete arsenic methylation capacity. Future prospective studies are needed to confirm the association between arsenic methylation capacity and atherosclerosis-related outcomes.

Arsenic-induced genotoxicity and genetic susceptibility to arsenic-related pathologies

The arsenic (As) exposure represents an important problem in many parts of the World. Indeed, it is estimated that over 100 million individuals are exposed to arsenic, mainly through a contamination of groundwaters. Chronic exposure to As is associated with adverse effects on human health such as cancers, cardiovascular diseases, neurological diseases and the rate of morbidity and mortality in populations exposed is alarming. The purpose of this review is to summarize the genotoxic effects of As in the cells as well as to discuss the importance of signaling and repair of arsenic-induced DNA damage. The current knowledge of specific polymorphisms in candidate genes that confer susceptibility to arsenic exposure is also reviewed. We also discuss the perspectives offered by the determination of biological markers of early effect on health, incorporating genetic polymorphisms, with biomarkers for exposure to better evaluate exposure-response clinical relationships as well as to develop novel preventative strategies for arsenic- health effects.

A prospective study of tobacco smoking and mortality in Bangladesh

Background

Limited data are available on smoking-related mortality in low-income countries, where both chronic disease burden and prevalence of smoking are increasing.

Methods

Using data on 20, 033 individuals in the Health Effects of Arsenic Longitudinal Study (HEALS) in Bangladesh, we prospectively evaluated the association between tobacco smoking and all-cause, cancer, and cardiovascular disease mortality during ∼7.6 years of follow-up.

Cox proportional hazards models were used to estimate hazard ratios (HRs) and their 95% confidence intervals (CIs) for deaths from all-cause, cancer, CVD, ischemic heart disease (IHD), and stroke, in relation to status, duration, and intensity of cigarette/bidi and hookah smoking.

Results

Among men, cigarette/bidi smoking was positively associated with all-cause (HR 1.40, 95% CI 1.06 1.86) and cancer mortality (HR 2.91, 1.24 6.80), and there was a dose-response relationship between increasing intensity of cigarette/bidi consumption and increasing mortality. An elevated risk of death from ischemic heart disease (HR 1.87, 1.08 3.24) was associated with current cigarette/bidi smoking. Among women, the corresponding HRs were 1.65 (95% CI 1.16 2.36) for all-cause mortality and 2.69 (95% CI 1.20 6.01) for ischemic heart disease mortality. Similar associations were observed for hookah smoking. There was a trend towards reduced risk for the mortality outcomes with older age at onset of cigarette/bidi smoking and increasing years since quitting cigarette/bibi smoking among men. We estimated that cigarette/bidi smoking accounted for about 25.0% of deaths in men and 7.6% in women.

Conclusions

Tobacco smoking was responsible for substantial proportion of premature deaths in the Bangladeshi population, especially among men. Stringent measures of tobacco control and cessation are needed to reduce tobacco-related deaths in Bangladesh.

Sodium arsenite-induced cardiotoxicity in rats: protective role of p-coumaric acid, a common dietary polyphenol

This study was performed to investigate the ameliorative role of p-coumaric acid against sodium arsenite-induced cardiotoxicity in rats. Sodium arsenite (5 mg/kg/b.wt) was orally administered once a day for 30 days to the animals to induce cardiotoxicity. After the experimental period, cardiotoxicity was assessed by estimating the levels of lipid peroxidation, anti-oxidant status (superoxide dismutase, catalase, glutathione peroxidase, glutathione S-transferase, glutathione reductase, total reduced glutathione, protein sulfyhydryl and non-protein sulfhydryl groups) and DNA fragmentation in the cardiac tissue of control and experimental rats. In addition, cardiac tissue specific serum markers (triacylglycerides, total cholesterol, low-density lipoprotein cholesterol and high density lipoprotein cholesterol) in serum and histopathological changes in the cardiac tissue were also evaluated. From the results obtained in our study, sodium arsenite administration to the rats increased lipid peroxidation, DNA fragmentation, triacylglycerides, total cholesterol and low-density lipoprotein cholesterol, whereas antioxidant status and high-density lipoprotein cholesterol were found to be reduced. However, p-coumaric acid (75 and100 mg/kg/b.wt) treatment orally once per day for 30 days, immediately before a daily administration of sodium arsenite protected the abnormal biochemical abnormalities observed in the cardiac tissue of sodium arsenite treated rats as evidenced by the cardiac histopathology. For comparison purpose, a standard antioxidant vitamin C (100 mg/kg/b.wt) was used. In conclusion, this study concluded that p-coumaric acid could be a promising candidate for protecting the sodium arsenite-induced cardiotoxicity in rats through its antioxidant character.

Individual variations in arsenic metabolism in Vietnamese: the association with arsenic exposure and GSTP1 genetic polymorphism

We investigated the association of As exposure and genetic polymorphism in glutathione S-transferase π1 (GSTP1) with As metabolism in 190 local residents from the As contaminated groundwater areas in the Red River Delta, Vietnam. Total As concentrations in groundwater ranged from <0.1 to 502 μg l(-1). Concentrations of dimethylarsinic acid (DMA(V)), monomethylarsonic acid (MMA(V)), and arsenite (As(III)) in human urine were positively correlated with total As levels in the groundwater, suggesting that people in these areas may be exposed to As through the groundwater. The concentration ratios of urinary As(III)/arsenate (As(V)) and MMA(V)/inorganic As (IA; As(III) + As(V))(M/I), which are indicators of As metabolism, increased with the urinary As level. Concentration and proportion of As(III) were high in the wild type of GSTP1 Ile105Val compared with the hetero type, and these trends were more pronounced in the higher As exposure group (>56 μg l(-1) creatinine in urine), but not in the lower exposure group. In the high As exposure group, As(III)/As(V) ratios in the urine of wild type of GSTP1 Ile105Val were significantly higher than those of the hetero type, while the opposite trend was observed for M/I. These results suggest that the excretion and metabolism of IA may depend on both the As exposure level and the GSTP1 Ile105Val genotype.

Heavy metal poisoning and cardiovascular disease

Cardiovascular disease (CVD) is an increasing world health problem. Traditional risk factors fail to account for all deaths from CVD. It is mainly the environmental, dietary and lifestyle behavioral factors that are the control keys in the progress of this disease. The potential association between chronic heavy metal exposure, like arsenic, lead, cadmium, mercury, and CVD has been less well defined. The mechanism through which heavy metals act to increase cardiovascular risk factors may act still remains unknown, although impaired antioxidants metabolism and oxidative stress may play a role. However, the exact mechanism of CVD induced by heavy metals deserves further investigation either through animal experiments or through molecular and cellular studies. Furthermore, large-scale prospective studies with follow up on general populations using appropriate biomarkers and cardiovascular endpoints might be recommended to identify the factors that predispose to heavy metals toxicity in CVD. In this review, we will give a brief summary of heavy metals homeostasis, followed by a description of the available evidence for their link with CVD and the proposed mechanisms of action by which their toxic effects might be explained. Finally, suspected interactions between genetic, nutritional and environmental factors are discussed.

Significantly increased risk of carotid atherosclerosis with arsenic exposure and polymorphisms in arsenic metabolism genes

Individual susceptibility to arsenic-induced carotid atherosclerosis might be associated with genetic variations in arsenic metabolism. The purpose of this study is to explore the interaction effect on risk of carotid atherosclerosis between arsenic exposure and risk genotypes of purine nucleoside phosphorylase (PNP), arsenic (+3) methyltransferase (As3MT), and glutathione S-transferase omega 1 (GSTO1) and omega 2 (GSTO2). A community-based case-control study was conducted in northeastern Taiwan to investigate the arsenic metabolic-related genetic susceptibility to carotid atherosclerosis. In total, 863 subjects, who had been genotyped and for whom the severity of carotid atherosclerosis had been determined, were included in the present study. Individual well water was collected and arsenic concentration determined using hydride generation combined with flame atomic absorption spectrometry. The result showed that a significant dose-response trend (P=0.04) of carotid atherosclerosis risk associated with increasing arsenic concentration. Non-significant association between genetic polymorphisms of PNP Gly51Ser, Pro57Pro, As3MT Met287Thr, GSTO1 Ala140Asp, and GSTO2 A-183G and the risk for development of carotid atherosclerosis were observed. However, the significant interaction effect on carotid atherosclerosis risk was found for arsenic exposure (>50μg/l) and the haplotypes of PNP (p=0.0115). A marked elevated risk of carotid atherosclerosis was observed in subjects with arsenic exposure of >50μg/l in drinking water and those who carried the PNP A-T haplotype and at least either of the As3MT risk polymorphism or GSTO risk haplotypes (OR, 6.43; 95% CI, 1.79-23.19). In conclusion, arsenic metabolic genes, PNP, As3MT, and GSTO, may exacerbate the formation of atherosclerosis in individuals with high levels of arsenic concentration in well water (>50μg/l).

Effects of abandoned arsenic mine on water resources pollution in north west of iran

BACKGROUND

Pollution due to mining activities could have an important role in health and welfare of people who are living in mining area. When mining operation finishes, environ-ment of mining area can be influenced by related pollution e.g. heavy metals emission to wa-ter resources. The present study was aimed to evaluate Valiloo abandoned arsenic mine ef-fects on drinking water resources quality and possible health effects on the residents of min-ing area in the North West of Iran.

METHODS

Water samples and some limited composite wheat samples in downstream of min-ing area were collected. Water samples were analyzed for chemical parameters according to standard methods. For determination of arsenic in water samples, Graphite Furnace Atomic Absorption Spectrometric Method (GFAAS) and for wheat samples X - Ray Fluorescence (XRF) and Inductively Coupled Plasma Method (ICP) were used. Information about possible health effects due to exposure to arsenic was collected through interviews in studied villages and health center of Herris City.

RESULTS

The highest concentrations of arsenic were measured near the mine (as high as 2000 µg/L in Valiloo mine opening water). With increasing distance from the mine, concentration was decreased. Arsenic was not detectable in any of wheat samples. Fortunately, no health effects had been reported between residents of studied area due to exposure to arsenic.

CONCLUSION

Valiloo abandoned arsenic mine has caused release of arsenic to the around en-vironment of the mine, so arsenic concentration has been increased in the groundwater and also downstream river that requires proper measures to mitigate spread of arsenic.

GT-repeat polymorphism in the heme oxygenase-1 gene promoter is associated with cardiovascular mortality risk in an arsenic-exposed population in northeastern Taiwan

Inorganic arsenic has been associated with increased risk of atherosclerotic vascular disease and mortality in humans. A functional GT-repeat polymorphism in the heme oxygenase-1 (HO-1) gene promoter is inversely correlated with the development of coronary artery disease and restenosis after clinical angioplasty. The relationship of HO-1 genotype with arsenic-associated cardiovascular disease has not been studied. In this study, we evaluated the relationship between the HO-1 GT-repeat polymorphism and cardiovascular mortality in an arsenic-exposed population. A total of 504 study participants were followed up for a median of 10.7 years for occurrence of cardiovascular deaths (coronary heart disease, cerebrovascular disease, and peripheral arterial disease). Cardiovascular risk factors and DNA samples for determination of HO-1 GT repeats were obtained at recruitment. GT repeats variants were grouped into the S (<27 repeats) or L allele (≥ 27 repeats). Relative mortality risk was estimated using Cox regression analysis, adjusted for competing risk of cancer and other causes. For the L/L, L/S, and S/S genotype groups, the crude mortalities for cardiovascular disease were 8.42, 3.10, and 2.85 cases/1000 person-years, respectively. After adjusting for conventional cardiovascular risk factors and competing risk of cancer and other causes, carriers with class S allele (L/S or S/S genotypes) had a significantly reduced risk of cardiovascular mortality compared to non-carriers (L/L genotype) [OR, 0.38; 95% CI, 0.16-0.90]. In contrast, no significant association was observed between HO-1 genotype and cancer mortality or mortality from other causes. Shorter (GT)n repeats in the HO-1 gene promoter may confer protective effects against cardiovascular mortality related to arsenic exposure.

GT-repeat polymorphism in the heme oxygenase-1 gene promoter and the risk of carotid atherosclerosis related to arsenic exposure

BACKGROUND

Arsenic is a strong stimulus of heme oxygenase (HO)-1 expression in experimental studies in response to oxidative stress caused by a stimulus. A functional GT-repeat polymorphism in the HO-1 gene promoter was inversely correlated to the development of coronary artery disease in diabetics and development of restenosis following angioplasty in patients. The role of this potential vascular protective factor in carotid atherosclerosis remains unclear. We previously reported a graded association of arsenic exposure in drinking water with an increased risk of carotid atherosclerosis. In this study, we investigated the relationship between HO-1 genetic polymorphism and the risk of atherosclerosis related to arsenic.

METHODS

Three-hundred and sixty-seven participants with an indication of carotid atherosclerosis and an additional 420 participants without the indication, which served as the controls, from two arsenic exposure areas in Taiwan, a low arsenic-exposed Lanyang cohort and a high arsenic-exposed LMN cohort, were studied. Carotid atherosclerosis was evaluated using a duplex ultrasonographic assessment of the extracranial carotid arteries. Allelic variants of (GT)n repeats in the 5'-flanking region of the HO-1 gene were identified and grouped into a short (S) allele (< 27 repeats) and long (L) allele (≥ 27 repeats). The association of atherosclerosis and the HO-1 genetic variants was assessed by a logistic regression analysis, adjusted for cardiovascular risk factors.

RESULTS

Analysis results showed that arsenic's effect on carotid atherosclerosis differed between carriers of the class S allele (OR 1.39; 95% CI 0.86-2.25; p = 0.181) and non-carriers (OR 2.65; 95% CI 1.03-6.82; p = 0.044) in the high-exposure LMN cohort. At arsenic exposure levels exceeding 750 μg/L, difference in OR estimates between class S allele carriers and non-carriers was borderline significant (p = 0.051). In contrast, no such results were found in the low-exposure Lanyang cohort.

CONCLUSIONS

This exploratory study suggests that at a relatively high level of arsenic exposure, carriers of the short (GT)n allele (< 27 repeats) in the HO-1 gene promoter had a lower probability of developing carotid atherosclerosis than non-carriers of the allele after long-term arsenic exposure via ground water. The short (GT)n repeat in the HO-1 gene promoter may provide protective effects against carotid atherosclerosis in individuals with a high level of arsenic exposure.

Urinary arsenic methylation capability and carotid atherosclerosis risk in subjects living in arsenicosis-hyperendemic areas in southwestern Taiwan

Long-term exposure to inorganic arsenic from artesian drinking well water is associated with carotid atherosclerosis in the Blackfoot Disease (BFD)-hyperendemic area in Taiwan. The current study examined the arsenic methylation capacity and its risk on carotid atherosclerosis. A total of 304 adults (158 men and 146 women) residing in the BFD-hyperendemic area were included. The extent of carotid atherosclerosis was assessed by duplex ultrasonography. Chronic arsenic exposure was estimated by an index of cumulative arsenic exposure (CAE) and the duration of artesian well water consumption. Urinary levels of inorganic arsenite [As(III)], arsenate [As(V)], monomethylarsonic acid [MMA(V)] and dimethylarsinic acid [DMA(V)] were determined by high performance liquid chromatography linked on-line to a hydride generator and atomic absorption spectrometry (HPLC-HG-AAS). The percentage of arsenic species, primary methylation index [PMI=MMA(V)/(As(III)+As(V)] and secondary methylation index [SMI=DMA(V)/MMA(V)] were calculated and employed as indicators of arsenic methylation capacity. Results showed that women and younger subjects had a more efficient arsenic methylation capacity than did men and the elderly. Carotid atherosclerosis cases had a significantly greater percentage of MMA(V) [%MMA(V)] and a lower percentage of DMA [%DMA (V)] compared to controls. Subjects in the highest two tertiles of PMI with a median of CAE >0 mg/L-year had an odds ratio (OR) and a 95% confidence interval (CI) of carotid atherosclerosis of 2.61 and 0.98-6.90 compared to those in the highest two tertiles of PMI with a CAE=0 mg/L-year. We conclude that individuals with greater exposure to arsenic and lower capacity to methylate inorganic arsenic may be at a higher risk to carotid atherosclerosis.

Risk of carotid atherosclerosis is associated with low serum paraoxonase (PON1) activity among arsenic exposed residents in Southwestern Taiwan

To understand whether human paraoxonase 1 (PON1) would modulate the risk for arsenic-related atherosclerosis, we studied 196 residents from an arseniasis-endemic area in Southwestern Taiwan and 291 age- and sex-matched residents from a nearby control area where arsenic exposure was found low. Carotid atherosclerosis was defined by a carotid artery intima-media wall thickness (IMT) of >1.0 mm. Prevalence of carotid atherosclerosis was increased in the arseniasis-endemic area as compared to the control area after adjustment for conventional risk factors (OR=2.20, p<0.01). The prevalence was positively associated with cumulative arsenic exposure (mg/L-year) in a dose-dependent manner. Multiple logistic regression analysis showed that in the endemic group, low serum PON1 activity was an independent risk factor for atherosclerosis (OR=4.18 low vs. high, p<0.05). For those of low PON1 activity and high cumulative arsenic exposure, the odds ratio for the prevalence of atherosclerosis was further increased up to 5.68 (p<0.05). No significant association was found between atherosclerosis and four polymorphisms of the PON gene cluster (PON1 -108C/T, PON1 Q192R, PON2 A148G, PON2 C311S). However, genetic frequencies of certain alleles including PON1 Q192, PON2 G148 and PON2 C311 were found increased in the endemic group as compared to the controls and a general Chinese population, indicating a possible survival selection in the endemic group after a long arsenic exposure history. Our results showed a significant joint effect between arsenic exposure and serum PON1 activity on carotid atherosclerosis, suggesting that subjects of low PON1 activity may be more susceptible to arsenic-related cardiovascular disease.

Arsenic exposure at low-to-moderate levels and skin lesions, arsenic metabolism, neurological functions, and biomarkers for respiratory and cardiovascular diseases: review of recent findings from the Health Effects of Arsenic Longitudinal Study (HEALS) in Bangladesh

The contamination of groundwater by arsenic in Bangladesh is a major public health concern affecting 35-75 million people. Although it is evident that high levels (>300 microg/L) of arsenic exposure from drinking water are related to adverse health outcomes, health effects of arsenic exposure at low-to-moderate levels (10-300 microg/L) are not well understood. We established the Health Effects of Arsenic Longitudinal Study (HEALS) with more than 20,000 men and women in Araihazar, Bangladesh, to prospectively investigate the health effects of arsenic predominantly at low-to-moderate levels (0.1 to 864 microg/L, mean 99 microg/L) of arsenic exposure. Findings to date suggest adverse effects of low-to-moderate levels of arsenic exposure on the risk of pre-malignant skin lesions, high blood pressure, neurological dysfunctions, and all-cause and chronic disease mortality. In addition, the data also indicate that the risk of skin lesion due to arsenic exposure is modifiable by nutritional factors, such as folate and selenium status, lifestyle factors, including cigarette smoking and body mass index, and genetic polymorphisms in genes related to arsenic metabolism. The analyses of biomarkers for respiratory and cardiovascular functions support that there may be adverse effects of arsenic on these outcomes and call for confirmation in large studies. A unique strength of the HEALS is the availability of outcome data collected prospectively and data on detailed individual-level arsenic exposure estimated using water, blood and repeated urine samples. Future prospective analyses of clinical endpoints and related host susceptibility will enhance our knowledge on the health effects of low-to-moderate levels of arsenic exposure, elucidate disease mechanisms, and give directions for prevention.

Arsenic and cardiovascular disease

Chronic arsenic exposure is a worldwide health problem. Although arsenic-induced cancer has been widely studied, comparatively little attention has been paid to arsenic-induced vascular disease. Epidemiological studies have shown that chronic arsenic exposure is associated with increased morbidity and mortality from cardiovascular disease. In addition, studies suggest that susceptibility to arsenic-induced vascular disease may be modified by nutritional factors in addition to genetic factors. Recently, animal models for arsenic-induced atherosclerosis and liver sinusoidal endothelial cell dysfunction have been developed. Initial studies in these models show that arsenic exposure accelerates and exacerbates atherosclerosis in apolipoprotein E-knockout mice. Microarray studies of liver mRNA and micro-RNA abundance in mice exposed in utero suggest that a permanent state of stress is induced by the arsenic exposure. Furthermore, the livers of the arsenic-exposed mice have activated pathways involved in immune responses suggesting a pro-hyperinflammatory state. Arsenic exposure of mice after weaning shows a clear dose-response in the extent of disease exacerbation. In addition, increased inflammation in arterial wall is evident. In response to arsenic-stimulated oxidative signaling, liver sinusoidal endothelium differentiates into a continuous endothelium that limits nutrient exchange and waste elimination. Data suggest that nicotinamide adenine dinucleotide phosphate oxidase-derived superoxide or its derivatives are essential second messengers in the signaling pathway for arsenic-stimulated vessel remodeling. The recent findings provide future directions for research into the cardiovascular effects of arsenic exposure.

Genetic variations associated with interindividual sensitivity in the response to arsenic exposure

People are exposed to arsenic compounds environmentally, occupationally or therapeutically. In some areas, where arsenic is present in high proportions in the drinking water, this exposure represents an important health concern. Chronic exposure to arsenic leads to hyperkeratosis and loss of skin pigmentation, as well as to significant increases of different types of cancer in skin, lung, bladder and liver; in addition, other pathologies, such as vascular diseases, hepatotoxicity and diabetes, have also been related to arsenic exposure. Since high interindividual variability is observed among people exposed to equivalent doses, genetic susceptibility factors have been postulated to be involved. When inorganic arsenic enters into the body it undergoes metabolic conversion, in a process where methylation plays a crucial role. Trivalent forms, both inorganic and organic, are the most toxic and genotoxic and, for this reason, metabolic variations owing to variant alleles in genes involved in such a process have been the aim of several studies. Genes involved in other mechanisms, such as antioxidant defense and DNA-repair lesions, among others, have also been the subject of association studies. A survey of those studies related to individual susceptibility is summarized here. Results with genes involved in folate one-carbon metabolism and in arsenic transport across the cell membrane provide promising data for future studies.

Risk of erectile dysfunction induced by arsenic exposure through well water consumption in Taiwan

BACKGROUND

Erectile dysfunction (ED) has a profound impact on the quality of life of many men. Many risk factors are associated with ED, such as aging, sex hormone levels, hypertension, cardiovascular diseases, and diabetes mellitus. Arsenic exposure could damage peripheral vessels and increase the risk of cardiovascular disease. However, the relationship between arsenic exposure and ED has seldom been evaluated.

OBJECTIVES

In this study we aimed to investigate whether exposure to arsenic enhances the risk of ED.

METHODS

We recruited 177 males >or= 50 years of age through health examinations conducted in three hospitals in Taiwan. We used a questionnaire (International Index of Erectile Function-5) to measure the level of erectile function. Sex hormones, including total testosterone and sex hormone-binding globulin, were determined by radioimmunoassay. We used another standardized questionnaire to collect background and behavioral information (e.g., cigarette smoking; alcohol, tea, or coffee drinking; and physical activity).

RESULTS

The prevalence of ED was greater in the arsenic-endemic area (83.3%) than in the non-arsenic-endemic area (66.7%). Subjects with arsenic exposure > 50 ppb had a significantly higher risk of developing ED than those with exposure <or= 50 ppb, after adjusting for age, cigarette smoking, diabetes mellitus, hypertension, and cardiovascular disease [odds ratio (OR) = 3.4]. Results also showed that the risk of developing severe ED was drastically enhanced by arsenic exposure (OR = 7.5), after adjusting for free testosterone and traditional risk factors of ED.

CONCLUSIONS

Results suggested that chronic arsenic exposure has a negative impact on erectile function.

Risk of carotid atherosclerosis associated with genetic polymorphisms of apolipoprotein E and inflammatory genes among arsenic exposed residents in Taiwan

Arsenic had been reported to be associated with carotid atherosclerosis. However, there were few studies to evaluate the association between the susceptible gene of lipid metabolism and inflammation and carotid atherosclerosis among arsenic exposure residents. The aim of the study was to investigate the associations between the genetic polymorphisms of APOE and MCP-1 and the risk of carotid atherosclerosis among residents of Lanyang Basin in Taiwan which was a newly confirmed arsenic-endemic area. In total, 479 residents who had been genotyped of these two genes and examined the severity of carotid atherosclerosis were included in this study. The study subjects with carotid intima media thickness (IMT) >or=1.0 mm or with the observable plaque in the extracranial carotid artery were diagnosed as carotid atherosclerosis. A significantly age- and gender-adjusted odds ratio of 2.0 for the development of carotid atherosclerosis was observed in study subjects with epsilon4 allele of APOE than those without epsilon4 allele. Compared with study subjects who carried wild genotypes of APOE and MCP-1, those with both risk genotypes of APOE and MCP-1 had 2.5-fold risk of carotid atherosclerosis after adjustment for age and gender, revealing a significant dose-response relationship between number of risk genotypes of these genes and risk of carotid atherosclerosis. Additionally, study subjects with two risk genotypes of APOE and MCP-1 and either had ingested well water contained arsenic level >10 microg/L or had arsenic exposure >0.22 mg/L-year would have strikingly highest risk of 10.3-fold and 15.7-fold, respectively, for the development carotid atherosclerosis, showing significant joint effect of arsenic exposure and risk genotypes of APOE and MCP-1.