Association between hypertension and chronic arsenic exposure in drinking water: a cross-sectional study in Bangladesh

Hongjingtian alleviates arsenic-induced hepatocyte injury by inhibiting oxidative stress and endoplasmic reticulum stress

This study explored Hongjingtian's (HJT) protective effects against arsenic-induced hepatotoxicity. NaAsO2 (8 μM, 24 h)-damaged hepatocytes treated with HJT (50/100 mg/L) showed restored cell viability via CCK-8/LDH assays. HJT reduced arsenic-induced ROS, improved mitochondrial membrane potential, elevated SOD/CAT activity, lowered MDA, and suppressed apoptosis by downregulating Caspase-3/Bax while upregulating Bcl-2. Additionally, HJT alleviated endoplasmic reticulum stress (ERS). Mechanistically, HJT attenuated arsenic-induced hepatocyte apoptosis by mitigating oxidative stress and ERS via ROS reduction.

Arsenic Exposure-Related Hypertension in Bangladesh and Reduced Circulating Nitric Oxide Bioavailability

BACKGROUND

Hypertension is a major cause of death worldwide. Although arsenic exposure has been associated with the risk of hypertension, this association appears nonuniform due to inconsistent results from studies conducted in different populations. Moreover, hypertension is a complex condition with multiple underlying mechanisms and factors. One factor is impaired production and bioavailability of vascular nitric oxide (NO). However, the implications of the effects of arsenic exposure on circulating NO and its association with hypertension in humans are largely unknown.

OBJECTIVE

We investigated the dose-response relationship between arsenic exposure and hypertension with vascular NO levels as a potential mediator of arsenic-related hypertension in individuals exposed to a broad range of arsenic.

METHODS

A total of 828 participants were recruited from low- and high-arsenic exposure areas in Bangladesh. Participants' drinking water, hair, and nail arsenic concentrations were measured by inductively coupled plasma mass spectroscopy. Hypertension was defined as a systolic blood pressure (SBP) value of ≥ 140 and a diastolic (DBP) value of ≥ 90  mmHg . Serum NO levels reflected by total serum nitrite concentrations were measured by immunoassay. A formal causal mediation analysis was used to assess NO as a mediator of the association between arsenic level and hypertension.

RESULTS

Increasing concentrations of arsenic measured in drinking water, hair, and nails were associated with the increasing levels of SBP and DBP. The odds of hypertension were dose-dependently increased by arsenic even in participants exposed to relatively low to moderate levels (10 - 50 μ g / L ) of water arsenic [odds ratios (ORs) and 95% confidence intervals (CIs): 2.87 (95% CI: 1.28, 6.44), 2.67 (95% CI: 1.27, 5.60), and 5.04 (95% CI: 2.71, 9.35) for the 10 - 50 μ g / L , 50.01 - 150 μ g / L , and > 150 μ g / L groups, respectively]. Causal mediation analysis showed a significant mediating effect of NO on arsenic-related SBP, DBP, and hypertension.

CONCLUSION

Increasing exposure to arsenic was associated with increasing odds of hypertension. The association was mediated through the reduction of vascular NO bioavailability, suggesting that impaired NO bioavailability was a plausible underlying mechanism of arsenic-induced hypertension in this Bangladeshi population. https://doi.org/10.1289/EHP13018.

Review Article on Molecular Mechanism of Regulation of Hypertension by Macro-elements (Na, K, Ca and Mg), Micro-elements/Trace Metals (Zn and Cu) and Toxic Elements (Pb and As)

Hypertension (HT) is a medical condition arising due to increase in blood pressure (BP) prevalent worldwide. The balanced dietary intakes of macro-elements and micro-elements including Na, K, Ca, Mg, Zn, and Cu have been described to maintain BP in humans by regulating the osmolarity of blood, cells/tissues, prevention of generation of oxidative and nitrosative stress (OANS), and endothelial damage through their functioning as important components of renin-angiotensin-aldosterone system (RAAS), antioxidant enzyme defense system, and maintenance of blood vascular-endothelial and vascular smooth muscle cell (VSMC) functions. However, inadequate/excess dietary intakes of Na/K, Ca/Mg, and Zn/Cu along with higher Pb and As exposures recognized to induce HT through common mechanisms including the followings: endothelial dysfunctions due to impairment of vasodilatation, increased vasoconstriction and arterial stiffness, blood clotting, inflammation, modification of sympathetic activity and higher catecholamine release, increased peripheral vascular resistance, and cardiac output; increased OANS due to reduced and elevated activities of extracellular superoxide dismutase and NAD(P)H oxidase, less nitric oxide bioavailability, decrease in cGMP and guanylate cyclase activity, increase in intracellular Ca2+ ions in VSMCs, and higher pro-inflammatory cytokines; higher parathyroid and calcitriol hormones; activation/suppression of RAAS resulting imbalance in blood Na+, K+, and water regulated by renin, angiotensin II, and aldosterone through affecting natriuresis/kaliuresis/diuresis; elevation in serum cholesterol and LDL cholesterol, decrease in HDL cholesterol due to defect in lipoprotein metabolism. The present study recommends the need to review simple dietary mineral intervention studies/supplementation trials before keeping their individual dietary excess intakes/exposures in consideration because their interactions lead to elevation and fall of their concentrations in body affecting onset of HT.

Safeguarding drinking water: A brief insight on characteristics, treatments and risk assessment of contamination

Water pollution stands as a critical worldwide concern, bearing extensive repercussions that extend to human health and the natural ecosystem. The sources of water pollution can be diverse, arising from natural processes and human activities and the pollutants may range from chemical and biological agents to physical and radiological contaminants. The contamination of water disrupts the natural functioning of the system, leading to both immediate and prolonged health problems. Various technologies and procedures, ranging from conventional to advanced, have been developed to eliminate water impurities, with the choice depending on the type and level of contamination. Assessing risks is a crucial element in guaranteeing the safety of drinking water. Till now, research is continuing the removal of contaminates for the sake of supplying safe drinking water. The study examined physical, inorganic, organic, biological and radiological contaminants in drinking water. It looked at where these contaminants come from, their characteristics, the impact they have and successful methods used in real-world situations to clean the contaminated water. Risk assessment methodologies associated with the use of unsafe drinking water as future directives are also taken into consideration in the present study for the benefit of public concern. The manuscript introduces a comprehensive study on water pollution, focusing on assessing and mitigating risks associated with physical, inorganic, organic, biological and radiological contaminants in drinking water, with a novel emphasis on future directives and sustainable solutions for public safety.

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.

Mechanisms Associated with Cognitive and Behavioral Impairment Induced by Arsenic Exposure

Arsenic (As) is a metalloid naturally present in the environment, in food, water, soil, and air; however, its chronic exposure, even with low doses, represents a public health concern. For a long time, As was used as a pigment, pesticide, wood preservative, and for medical applications; its industrial use has recently decreased or has been discontinued due to its toxicity. Due to its versatile applications and distribution, there is a wide spectrum of human As exposure sources, mainly contaminated drinking water. The fact that As is present in drinking water implies chronic human exposure to this metalloid; it has become a worldwide health problem, since over 200 million people live where As levels exceed safe ranges. Many health problems have been associated with As chronic exposure including cancer, cardiovascular diseases, gastrointestinal disturbances, and brain dysfunctions. Because As can cross the blood-brain barrier (BBB), the brain represents a target organ where this metalloid can exert its long-term toxic effects. Many mechanisms of As neurotoxicity have been described: oxidative stress, inflammation, DNA damage, and mitochondrial dysfunction; all of them can converge, thus leading to impaired cellular functions, cell death, and in consequence, long-term detrimental effects. Here, we provide a current overview of As toxicity and integrated the global mechanisms involved in cognitive and behavioral impairment induced by As exposure show experimental strategies against its neurotoxicity.

Levels, origins and probabilistic health risk appraisal for trace elements in drinking water from Lhasa, Tibet

Due to the lack of monitoring systems and water purification facilities, residents in western China may face the risk of drinking water pollution. Therefore, 673 samples were collected from Lhasa's agricultural and pastoral areas to reveal the status quo of drinking water. We used inductively coupled plasma-mass spectrometry to determine trace elements concentrations for water quality appraisal, source apportionment, and health risk assessment. The results indicate that concentrations of V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Cd, Ba, and Pb are below the guidelines, while As concentrations in a few samples exceed the standard. All samples were classified into "excellent water" for drinking purpose based on Entropy-weighted water quality index. Thereafter by principal component analysis, three potential sources of trace elements were extracted, including natural, anthropogenic, and mining activities. It is worth noting that geotherm and mining exploitation does not threaten drinking water safety. Finally, health risks were assessed using Monte Carlo technique. We found that the 95th percentiles of hazard index are 1.80, 0.80, and 0.79 for children, teenagers, and adults, indicating a non-carcinogenic risk for children, but no risks for the latter two age groups. In contrast, the probabilities of unacceptable cautionary risk are 7.15, 2.95 and 0.69% through exposure to Cr, Ni, As, and Cd for adults, children, and teenagers. Sensitivity analyses reveal As concentration and ingestion rate are most influential factors to health risk. Hence, local governments should pay more attention to monitoring and removal of As in the drinking water.

Short-term exposure to some heavy metals carried with PM10 and cardiovascular system biomarkers during dust storm

This study aimed to evaluate the effect of short-term exposure to heavy metals (HM) extracted from PM10 on CB in workers' population in an outdoor space located in southern Iran during a dust storm. At first, 44 healthy and non-smoking workers were selected. Then PM10 and Blood samples were collected before and after the dust storm. Finally, HMs associated with PM10 measured by ICP-MS and its effect on the CB, including fibrinogen, CRP, TNF-α, and BP were estimated by ANOVA, Pearson correlation, and Odd Ratio (OR) in SPSS23. Based on the results, the concentration of PM10 and extracted HM such as Cr, As, and Cd was higher than the WHO/EPA standards in dust storms they increased the CB and BP remarkably. Moreover, the level of fibrinogen, blood pressure (BP) and TNF-α in dust storms were higher than in normal conditions (p < 0.05, OR > 3). In addition, As and Cd decreased fibrinogen concentration and systolic BP, respectively. Whereas, TNF-α was associated with concentration of Pb (R = - 0.85) on normal days. Consequently, the HM on PM10 such as As, interferes with the level of investigated CB. These results considered a potential risk for the residents in the southern regions of Iran.

Mechanisms of Arsenic Exposure-Induced Hypertension and Atherosclerosis: an Updated Overview

Arsenic is an abundant element in the earth's crust. In the environment and within the human body, this toxic element can be found in both organic and inorganic forms. Chronic exposure to arsenic can predispose humans to cardiovascular diseases including hypertension, stroke, atherosclerosis, and blackfoot disease. Oxidative damage induced by reactive oxygen species is a major player in arsenic-induced toxicity, and it can affect genes expression, inflammatory responses, and/or nitric oxide homeostasis. Exposure to arsenic in drinking water can lead to vascular endothelial dysfunction which is reflected by an imbalance between vascular relaxation and contraction. Arsenic has been shown to inactivate endothelial nitric oxide synthase leading to a reduction of the generation and bioavailability of nitric oxide. Ultimately, these effects increase the risk of vascular diseases such as hypertension and atherosclerosis. The present article reviews how arsenic exposure contributes to hypertension and atherosclerosis development.

Arsenic exposure promotes the emergence of cardiovascular diseases

A large number of studies conducted in the past decade 2010-2020 refer to the impact of arsenic (As) exposure on cardiovascular risk factors. The arsenic effect on humans is complex and mainly depends on the varying individual susceptibilities, its numerous toxic expressions and the variation in arsenic metabolism between individuals. In this review we present relevant data from studies which document the association of arsenic exposure with various biomarkers, the effect of several genome polymorphisms on arsenic methylation and the underling molecular mechanisms influencing the cardiovascular pathology. The corresponding results provide strong evidence that high and moderate-high As intake induce oxidative stress, inflammation and vessel endothelial dysfunction that are associated with increased risk for cardiovascular diseases (CVDs) and in particular hypertension, myocardial infarction, carotid intima-media thickness and stroke, ventricular arrhythmias and peripheral arterial disease. In addition, As exposure during pregnancy implies risks for blood pressure abnormalities among infants and increased mortality rates from acute myocardial infarction during early adulthood. Low water As concentrations are associated with increased systolic, diastolic and pulse pressure, coronary heart disease and incident stroke. For very low As concentrations the relevant studies are few. They predict a risk for myocardial infarction, stroke and ischemic stroke and incident CVD, but they are not in agreement regarding the risk magnitude.

Melatonin improves arsenic-induced hypertension through the inactivation of the Sirt1/autophagy pathway in rat

Arsenic (As), a metalloid chemical element, is classified as heavy metal. Previous studies proposed that As induces vascular toxicity by inducing autophagy, apoptosis, and oxidative stress. It has been shown that melatonin (Mel) can decrease oxidative stress and apoptosis, and modulate autophagy in different pathological situations. Hence, this study aimed to investigate the Mel effect on As-induced vascular toxicity through apoptosis and autophagy regulation. Forty male rats were treated with As (15 mg/kg; oral gavage) and Mel (10 and 20 mg/kg, intraperitoneally; i.p.) for 28 days. The systolic blood pressure (SBP) changes, oxidative stress markers, the aorta histopathological injuries, contractile and relaxant responses, the level of apoptosis (Bnip3 and caspase-3) and autophagy (Sirt1, Beclin-1 and LC3 II/I ratio) proteins were determined in rats aorta. The As exposure significantly increased SBP and enhanced MDA level while reduced GSH content. The exposure to As caused substantial histological damage in aorta tissue and changed vasoconstriction and vasorelaxation responses to KCl, PE, and Ach in isolated rat aorta. The levels of HO-1 and Nrf-2, apoptosis markers, Sirt1, and autophagy proteins also enhanced in As group. Interestingly, Mel could reduce changes in oxidative stress, blood pressure, apoptosis, and autophagy induced by As. On the other hand, Mel led to more increased the levels of Nrf-2 and HO-1 proteins compared with the As group. In conclusion, our findings showed that Mel could have a protective effect against As-induced vascular toxicity by inhibiting apoptosis and the Sirt1/autophagy pathway.

Association of selenium, arsenic, and other trace elements in drinking water and urine in residents of the plateau region in China

Drinking water is considered to be an important exposure pathway for humans to ingest trace elements; human urine samples are widely accepted as biometric substrates that can reflect human exposure to trace elements. The current study aimed at investigating the concentrations of trace elements including selenium (Se), arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), manganese (Mn), nickel (Ni), lead (Pb), and zinc (Zn) in drinking water and human urine in plateau region of China, determining the association among trace elements in drinking water and urine, and analyzing their associations with age and gender. The results showed that the majority of trace element concentrations were in the range of the World Health Organization (WHO 2011) guideline values, in both urine samples of male and female, and the median values were descending in the order: Zn > Cu > As > Se > Cr > Ni > Mn > Pb > Cd > Co. Selenium contributed to the excretion of As, Cr, Cu, Cd, and Zn in human body, group of 31-40 years appeared to present the greatest excretion ability in most of the trace elements. Weak positive correlations were observed between age and Mn in female urine samples, and negative correlations were observed between age and Se, As, Co, and Cu in male urine samples and between age and Co in female urine samples, respectively. Significant positive correlation was observed in As between drinking water and the whole human urine. In the same family, female seemed to show higher proportions of urinary As levels than male. This study will provide elementary information regarding trace element levels in drinking water and human urine in residents in plateau region of China and is helpful to provide reference for dietary nutrient trace element intake and effective control for local resident.

The association of arsenic exposure with hypertension and blood pressure: A systematic review and dose-response meta-analysis

Chronic arsenic exposure can induce cardiovascular diseases through oxidative stress injury, inflammation and endothelial dysfunction. However, evidence for hypertension related to chronic arsenic exposure remains limited and inconclusive. To investigate the association of arsenic exposure with hypertension, we reviewed cross-sectional, case-control and longitudinal studies among general population (only excluded pregnant woman and children). Compared with non-exposure (or low exposure) group, we assessed relationship between the exposure (or high exposure) of arsenic and hypertension or blood pressure. We also examined the dose-response relationship to provide a theoretical basis for precision interventions in the population by conducting a two-stage random-effects dose-response meta-analysis. The weighted mean difference (WMD) was calculated to compare the blood pressure of exposed and reference arsenic exposure groups. Twenty-seven studies comprising 117,769 participants were included. The pooled OR and RR for hypertension compared the highest with lowest arsenic exposure categories were 1.14 [95 % confidence interval (CI): 1.06-1.23] and 1.30 [95 % CI: 0.91-1.84], respectively. A dose-response assessment of six studies with the necessary data available demonstrated that the OR of hypertension increased with an increasement of arsenic exposure. The differences in systolic blood pressure levels between the exposed and reference groups were 4.03 mmHg (95 % CI: 1.24-6.82). The meta-analysis further revealed the significant association of chronic arsenic exposure with hypertension among cross-sectional studies and the marginal significance in cohort studies. Besides, arsenic was mainly associated with increasing systolic blood pressure but not significantly related to diastolic blood pressure. We also demonstrated statistical evidence of a nonlinear dose-response association. Details on mechanisms and cohort studies are required to elucidate population-wide health influence of chronic arsenic exposure.

Associations between urinary heavy metal concentrations and blood pressure in residents of Asian countries

BACKGROUND

Previous studies have suggested that exposures to heavy metals (arsenic, cadmium, lead, and selenium) may be associated with differences in blood pressure. However, the findings of these studies have been inconsistent. This study was performed to examine the associations between urinary heavy metal concentrations and blood pressure among residents of four Asian countries (Bangladesh, Indonesia, Nepal, and Vietnam).

METHODS

This cross-sectional study examined 1899 adults in four Asian countries. Urinary concentrations of heavy metals were measured by inductively coupled plasma mass spectrometry. A questionnaire survey was administered regarding individual characteristics. Anthropometric measurements (height and weight) were performed. Systolic and diastolic blood pressures were measured after a short rest. Multiple linear regression models were applied to investigate associations between urinary heavy metal concentrations and blood pressure after adjustments for age, sex, and body mass index.

RESULTS

The geometric means of the urinary concentrations of arsenic, cadmium, lead, and selenium were 84.6, 0.885, 2.09, and 16.5 μg/g creatinine, respectively. The urinary arsenic concentrations were slightly higher than those typically reported in non-polluted populations, while urinary cadmium, lead, and selenium concentrations were equivalent or slightly lower. The urinary lead concentrations were positively associated with both systolic and diastolic blood pressure, but urinary selenium concentrations were negatively associated with them.

CONCLUSIONS

Variations in the urinary concentrations of lead and selenium were associated with blood pressure at low levels of exposure/intake.

Arsenic (III) and/or Antimony (III) induced disruption of calcium homeostasis and endoplasmic reticulum stress resulting in apoptosis in mice heart

Arsenic (As) and antimony (Sb) are known as an environmental contaminant with cardiotoxicity properties. The endoplasmic reticulum (ER) is the largest calcium reservoir in the cell, and its calcium homeostasis disorder plays a vital role in endoplasmic reticulum stress (ERS) and apoptosis. The objective of this study was to investigate whether As and Sb induced apoptosis via endoplasmic reticulum stress (ERS) linked to calcium homeostasis disturbance. In this study, thirty-two adult mice were gavage-fed daily with As₂O₃ (4 mg/kg), SbCl₃ (15 mg/kg) and co-treat with SbCl₃ (15 mg/kg) and As₂O₃ (4 mg/kg) daily for 60 days. It was observed that As or/and Sb caused histopathological lesions and ER expansion of the heart. Meanwhile, the gene expression of ER Ca²⁺ release channels (RyR2 and IP3R) and calmodulin-dependent protein kinase II (CaMKII) increased while the levels of mRNA and protein of ER Ca²⁺ uptake channel (SERCA2) downregulated significantly compared to the controls. Then, As or/and Sb induced ERS and triggered the ER apoptotic pathway by activating unfolded protein response (UPR)-associated genes ((PERK, ATF6, IRE1, XBP1, JNK, GRP78), and apoptosis-related genes (Caspase12, Caspase3, p53, CHOP). Above indicators in As + Sb group became more severe than that of As group and Sb group. Overall, our results proved that the cardiotoxicity caused by As or/and Sb might be concerning disturbing calcium homeostasis, which induced apoptosis through the ERS pathway.

Dose-response meta-analysis of arsenic exposure in drinking water and hypertension

Background

Based on the cross-sectional and cohort studies, exposure to As via drinking water can cause hypertension.

Methods

We searched PubMed, ISI WOS, and Scopus for relevant studies up to 1 January 2018 using related keywords. The meta-analysis was done on 10 studies (n = 28255) that report Odds Ratio for hypertension. The extracted ORs between As concentration and hypertension were pooled using random effect models. Study heterogeneity was analyzed using I ².

Results

The estimated adjusted OR for association between As and hypertension was 1.44 (95% CI: 1.12, 1.84) with I ² = 71%. Dose-Response analysis showed a linear relationship between As and hypertension (OR = 1.0008 95% CI: 1.0003, 1.001). In general, by increase of each unit in arsenic concentration, odds of the hypertension would increase as 0.08%.

Conclusion

There was a significant relationship between As exposure and hypertension.

Arsenic Exposure and Incident Hypertension of Adult Residents Living in Rural Areas Along the Yangtze River, Anhui, China

OBJECTIVE

As a widespread toxic metal, arsenic had potential effect for hypertensive. We evaluated the association between urinary arsenic and the incidence of hypertension in adult residents along the Yangtze River of China.

METHODS

We conducted the study of 1358 adults 18 to 74 years of age from Chizhou, Maanshan, and Tongling of Anhui province, who participated in the baseline study in 2014 to 2015. Inductively coupled plasma optical emission spectrometry was used to measure urinary as of residents, and follow-up extended through 2016 to 2017.

RESULTS

We identified 275 hypertension events. The hazard ratios (HRs) of highest quartile arsenic compared with lowest quartile was 1.49 for hypertension events (95% confidence interval [CI] = 1.05 to 2.12), and HRs (≥P20 vs <P20) was 1.37 (95% CI = 1.02 to 1.84).

CONCLUSIONS

Higher level of arsenic exposure might play a role in increasing the incidence of hypertension.

Evaluation of different types of arsenic methylation and its relationship with metabolic syndrome in an area chronically exposed to arsenic

Evidence suggests that the relationship between arsenic metabolism and diseases, including metabolic syndrome, is complex. The aim of this study was to evaluate the different types of arsenic methylation and its association with metabolic syndrome in an arsenic endemic area. A cross-sectional study was conducted on 132 subjects from Shahid-Abad Village, Qazvin province, Iran (arsenic endemic area). Demographic characteristics, metabolic syndrome, and urinary arsenic species, including iAs (inorganic arsenic), MMA (monomethylarsonic acid), and DMA (dimethylarsinic acid) were measured for all patients and their relationship was analyzed by appropriate statistical methods. In this study, 34.5% of the participants had metabolic syndrome. The decrease in %MMA, increase in %DMA and increase in secondary methylation index (DMA/MMA) were associated with increased risk of metabolic syndrome (p<0.05). We did not find any association between the incidence of metabolic syndrome with primary methylation index (MMA/iAs) and %iAs (p>0.05). This study showed that the prevalence of metabolic syndrome was significantly higher in people with metabolic syndrome than in the general population. A closer examination revealed that the secondary methylation index is related to the metabolic syndrome and its components. Given the higher prevalence of cardiovascular disease and diabetes in patients with metabolic syndrome, it is necessary to change the pathogenesis of the disease using comprehensive management methods for decreasing patient complications.

Hypertension prevalence and its trend in Bangladesh: evidence from a systematic review and meta-analysis

BACKGROUND

Hypertension, itself being a major chronic condition, is one of the most significant risk factors for premature cardiovascular diseases and mortality. Hypertension is responsible for 13% of global deaths and three-quarters of the world's hypertensive population reside in low- and middle-income countries. Bangladesh is one of those countries that experiencing an epidemiological transition from communicable to non-communicable diseases, a nutritional transition from a traditional diet to process and fast food, and an increase in a sedentary lifestyle, resulting in increased hypertension prevalence. We carried out a systematic review and meta-analysis to identify existing research on hypertension prevalence in Bangladesh, summarize findings and assess its temporal change.

METHODS

We searched MEDLINE, EMBASE and PubMed and relevant references to identify studies on the prevalence of hypertension in Bangladesh. We used Random-effects meta-analysis to pool the prevalence estimates and performed subgroup analyses. We assessed heterogeneity, a trend in prevalence of hypertension and publication bias in selected studies.

RESULTS

Our search initially identified 735 articles and after removing duplicates, reviewing titles and abstracts, and screening full texts, 53 studies were finally selected. The studies comprised 305,432 subjects and reported overall, gender-specific, geographical location specific and criteria specific prevalence of hypertension. We identified the range of hypertension prevalence is from 1.10% to 75.0% and the overall weighted pooled prevalence of hypertension is 20.0%. An extremely high heterogeneity (I2 = 99.53%; Cochran Q-statistic p < 0.001) was observed in the prevalence of hypertension. Consequently, we performed subgroup analysis based on gender, age group and geographical location of the study participants, the cut-off level used to define hypertension, and the types of hypertension reported and presented our findings accordingly. An overall increasing trend of hypertension prevalence is also observed.

CONCLUSIONS

The prevalence of hypertension is high and rising in Bangladesh. Strategies targeting prevention are required to mitigate a further increase in the prevalence and reduce the morbidity and mortality associated with it.

Positive Association of Cardiovascular Disease (CVD) with Chronic Exposure to Drinking Water Arsenic (As) at Concentrations below the WHO Provisional Guideline Value: A Systematic Review and Meta-Analysis

To the best of our knowledge, a dose-response meta-analysis of the relationship between cardiovascular disease (CVD) and arsenic (As) exposure at drinking water As concentrations lower than the WHO provisional guideline value (10 µg/L) has not been published yet. We conducted a systematic review and meta-analyses to estimate the pooled association between the relative risk of each CVD endpoint and low-level As concentration in drinking water both linearly and non-linearly using a random effects dose-response model. In this study, a significant positive association was found between the risks of most CVD outcomes and drinking water As concentration for both linear and non-linear models (p-value for trend < 0.05). Using the preferred linear model, we found significant increased risks of coronary heart disease (CHD) mortality and CVD mortality as well as combined fatal and non-fatal CHD, CVD, carotid atherosclerosis disease and hypertension in those exposed to drinking water with an As concentration of 10 µg/L compared to the referent (drinking water As concentration of 1 µg/L) population. Notwithstanding limitations included, the observed significant increased risks of CVD endpoints arising from As concentrations in drinking water between 1 µg/L and the 10 µg/L suggests further lowering of this guideline value should be considered.

Morbidity profile of communities in Bhopal city (India) vis-à-vis distance of residence from Union Carbide India Limited plant and drinking water usage pattern

Objective:

A cross-sectional study was undertaken to assess the prevalence of morbidities in communities residing at variable distances from the closed down insecticide manufacturing plant premises of Union Carbide India Limited (UCIL), Bhopal, India and to determine association of morbidities, if any, with their drinking water usage pattern and distance of localities from the UCIL plant.

Materials and Methods:

A total of 10,827 individuals belonging to 2,184 families, residing within 0-1 km (Stratum I) and 2.5-5.0 km (Stratum II) radial distances from UCIL plant were surveyed and 9,306 of them (86%) were clinically examined. Data were analyzed to examine the association between the groups of morbidities, likely due to biological and chemical water contamination, and the distance of locality from the UCIL plant. Multiple logistic regression was used to explore the risk factors for morbidities.

Results:

Nearly similar prevalence (25.3% in stratum I, 25.8% in stratum II) and the trend of all-cause morbidities were recorded in the two strata. While morbidities related to gastrointestinal tract system (P < 0.05), auditory system (P < 0.01), neoplasm/cancers (P < 0.01) and congenital anomalies (P < 0.01) were significantly higher in stratum I, the prevalence of hypertension (6.4% stratum II, 4.7% stratum I; P < 0.01) and diabetes mellitus (3.4% stratum II, 2.0% stratum I; P < 0.001) was found significantly higher in stratum II. No association (P > 0.05) was observed between the prevalence of morbidities, likely due to the consumption of biologically or chemically contaminated drinking water, and the distance of locality/stratum from the UCIL plant.

Discussion and Conclusion:

By and large similar pattern of morbidities were recorded in the two strata suggesting that the communities, irrespective of the distance of their residences from UCIL plant or sources of their drinking water, are equally vulnerable to various morbidities.

Associations of exposure to metals with the risk of hypertension among an older population aged 40-75 years in rural southwest China

Metal exposure has recently been related to the risk of hypertension. However, the association remains unclear and relevant epidemiologic studies are limited. The present study aimed to assess the associations between exposure to metals and the odds of hypertension, as well as blood pressure (BP) levels. A total of 816 participants were enrolled in southwestern China. Hypertension was defined as a systolic BP (SBP) of ≥140 mmHg or diastolic BP (DBP) of ≥90 mmHg, a self-reported physician diagnosis, or current use of antihypertensive medication. Blood samples were used to detect the levels of exposure to metals, ie, magnesium (Mg), calcium (Ca), iron (Fe), zinc (Zn), arsenic (As), cadmium (Cd), copper (Cu) and lead (Pb). Logistic and linear regression models were used to assess the potential associations. The results show that positive trends for elevated odds of hypertension with increasing quartiles of Fe in a polluted area; and of Mg, Ca and Cu in an unpolluted area. Compared with those in the lowest quartiles, participants in the highest quartiles of Fe, Mg and Ca had 2.7-, 9.0- and 5.1-fold increased odds of hypertension, respectively. High blood Fe and Pb levels in the Cd-polluted area, and Mg and Fe in the unpolluted area were found to be related to increasing SBP and DBP levels. Our findings suggest that exposure to Fe and/or Pb in the polluted area; and Mg, Ca and Fe in the unpolluted area might increase the risk of hypertension or elevate BP levels.

Arsenic exposure through drinking Water and oxidative stress Status: A cross-sectional study in the Ayeyarwady region, Myanmar

Arsenic is a well-known toxic heavy metal that is naturally dispersed in groundwater. Whereas arsenic is widely accepted to be involved in oxidative stress damage, little is known about arsenic-induced oxidative damage in relationship to contaminated drinking water as a source. The aim of this study was to determine the association between arsenic exposure through drinking water and oxidative stress status by measuring levels of urinary 8-hydroxydeoxyguanosine (8-OHdG) as a biomarker of oxidative stress damage in a Myanmar population. A questionnaire-based survey and drinking water and urine sampling (n = 198) were performed to assess the association between arsenic exposure and urinary 8-OHdG concentration in the Ayeyarwady Region, Myanmar. Urinary arsenic concentrations were significantly correlated with drinking water arsenic concentrations (Spearman's rho = 0.32, p < 0.001). Multivariate linear regression analysis showed that higher urinary arsenic concentrations were significantly associated with higher 8-OHdG concentrations (coefficient = 0.09, 95% confidence interval, 0.03 - 0.15; p =  0.002). The present study identified that exposure to arsenic through drinking water could induce an increase in the urinary 8-OHdG concentration, reflecting increased oxidative DNA damage. These findings provide evidence that may explain the role of arsenic-induced oxidative stress in the pathophysiology of arsenic-induced diseases including cancers.

Health effects among a cohort exposed to low-level arsenic in a geothermal area of Tuscany, Italy

BACKGROUND

Studies on low-level As exposure have not found an association with cancer, while increased risks were reported for skin lesions, respiratory and cardiovascular diseases and reproductive outcomes. Prospective observational studies with individual exposure measures are needed to study low-level As exposure effects. In a geothermal area in Southern Tuscany (Italy), characterized by a natural presence of As in drinking water (< 50 µg/l), As urinary concentrations were measured in a survey in 1998 and cohort members were followed to evaluate the effects on health.

METHODS

Around 900 subjects (20-55 years old) randomly sampled in 4 municipalities of the area (Monte Amiata), have been followed from 1999 to 2015, by hospitalisation and mortality registries. Standardized Hospitalisation Ratios (SHRs) were performed, compared to a reference area. Competing-risks regression models were performed to test the association between As urinary concentration and risk of first hospitalisation.

RESULTS

SHRs show various increased risks, more frequently among males. Internal analyses show a positive association between As and skin diseases in the general population, the Hazard Ratio (HR) for 1 µg/l increase of As urinary concentration is 1.06 (90%CI 1.01-1.11) and in males, HR 1.08 (90%CI 1.02-1.14), between As and circulatory system diseases in males, HR 1.03 (90%CI 1.01-1.05).

CONCLUSIONS

The results suggest an effect on skin diseases and circulatory system diseases and, considering the relative young age of cohort members, they could be considered also as predictive of future severer diseases.

Effects of arsenic toxicity beyond epigenetic modifications

Worldwide chronic arsenic (As) poisoning by arsenic-contaminated groundwater is one of the most threatening public health problems. Chronic inorganic As (inAs) exposure has been associated with various forms of cancers and numerous other pathological effects in humans, collectively known as arsenicosis. Over the past decade, evidence indicated that As-induced epigenetic modifications have a role in the adverse effects on human health. The main objective of this article is to review the evidence on epigenetic modifications induced by arsenicals. The epigenetic components play a crucial role in the regulation of gene expression, at both transcriptional and posttranscriptional levels. We synthesized the large body of existing research on arsenic exposure and epigenetic mechanisms of health outcomes with an emphasis on recent publications. Changes in patterns of DNA methylation, histone posttranslational modifications, and microRNAs have been repeatedly observed after inAs exposure in laboratory studies and in studies of human populations. Such alterations have the potential to disturb cellular homeostasis, resulting in the modulation of key pathways in the As-induced carcinogenesis. The present article reviews recent data on As-induced epigenetic effects and concludes that it is time for heightened awareness of pathogenic arsenic exposure, particularly for pregnant women and children, given the potential for a long-lasting disturbed cellular homeostasis.

Serum lipid, lipoprotein and apolipoprotein profiles in workers exposed to low arsenic levels: Lipid profiles and occupational arsenic exposure

Epidemiologic studies have reported that exposure to arsenic (As) is associated with higher risk of cardiovascular disease (i.e., coronary heart disease and peripheral arterial heart disease) and mortality. This cross-sectional study aimed to compare serum lipid, lipoprotein, and apolipoprotein profiles in workers exposed to As. The subjects of this study included 57 workers exposed to As and 57 controls. Demographic characteristics and occupational information were collected through questionnaires. Exposure to As was assessed in indoor air of a workplace and determined using the creatinine values in the urine. Blood samples were collected using immunochemistry and nephelometry to measure the levels of total cholesterol (CHOL), triglycerides (TRIG), high-density lipoprotein (HDL), low-density lipoprotein (LDL), lipoprotein(a) (Lp(a)), apolipoprotein-A1 (Apo-A1), and apolipoprotein-B (Apo-B). No significant difference in the demographic data was detected between the two groups. Urinary As concentration was significantly (p<0.001) higher in exposed subjects than in the controls (13.4±6.1 and 4.4±6.1μg/gCreat, respectively). No statistically significant differences were observed in CHOL, TRIG, HDL, and LDL concentrations between the two groups. Lp(a), Apo-B, and Apo-B/Apo-A1 ratio values were significantly higher and the Apo-A1 level was significantly lower in the exposed group than in the control subjects. Regression analysis highlighted a significant (p<0.001) association between urinary As and Lp(a), Apo-A1, and Apo-B concentration, and Apo-B/Apo-A1 ratio. This study revealed the influence of As on apolipoproteins, suggesting a potential risk of cardiovascular diseases in subjects exposed to low levels of As.

Environmental Exposures and Cardiovascular Disease: A Challenge for Health and Development in Low- and Middle-Income Countries

Environmental exposures in low- and middle-income countries lie at the intersection of increased economic development and the rising public health burden of cardiovascular disease. Increasing evidence suggests an association of exposure to ambient air pollution, household air pollution from biomass fuel, lead, arsenic, and cadmium with multiple cardiovascular disease outcomes, including hypertension, coronary heart disease, stroke, and cardiovascular mortality. Although populations in low- and middle-income countries are disproportionately exposed to environmental pollution, evidence linking these exposures to cardiovascular disease is derived from populations in high-income countries. More research is needed to further characterize the extent of environmental exposures.

Assessment of heart rate response to exercise and recovery during treadmill testing in arsenic-exposed workers

BACKGROUND

Arsenic exposure is associated with various cardiovascular diseases. The aim of the present study was to assess cardiac autonomic function via heart rate response to exercise and recovery period of treadmill testing in arsenic-exposed workers.

METHODS

Sixty-five (65) occupationally arsenic-exposed workers and 35 healthy controls were enrolled. Blood and urinary arsenic levels were analyzed and symptom limited maximal treadmill exercise test were performed. Chronotropic response to exercise including age-predicted maximal heart rate (APMHR), heart rate reserve (HR_reserve ), age-predicted HR_reserve (APHR_reserve ) and adjusted HR_reserve and 1st-, 2nd-and 3rd-min heart rate recovery (HRR) indices were calculated.

RESULTS

Baseline clinical and echocardiographic parameters, exercise test duration, resting and maximal heart rate, peak exercise capacity, HR_reserve , APMHR, APHR_reserve , and adjusted HR_reserve were found to be similar between groups. HRR₁ (22.0 ± 4.3 vs. 24.3 ± 3.1 bpm, p = .003) and HRR₂ (43.2 ± 6.2 vs. 46.7 ± 6.4 bpm, p = .012) were significantly lower in arsenic-exposed workers compared to controls. Blood and urinary arsenic levels negatively correlated with HRR₁ (r = -.477, p < .001 and r = -.438, p < .001, respectively) and HRR₂ (r = -.507, p < .001 and r = -.412, p < .001 respectively).

CONCLUSIONS

Arsenic-exposed workers had lower HRR indices than normal subjects but chronotropic response were similar. Cardiac autonomic dysregulation may be one of the cardiovascular consequences of arsenic exposure.

Molecular insight of arsenic-induced carcinogenesis and its prevention

Population of India and Bangladesh and many other parts of the world are badly exposed to arsenic through drinking water. Due to non-availability of safe drinking water, they are dependent on arsenic-contaminated water. Generally, poverty level is high in those areas with lack of proper nutrition. Arsenic is considered to be an environmental contaminant and widely distributed in the environment due to its natural existence and anthropogenic applications. Contamination of arsenic in both human and animal could occur through air, soil, and other sources. Arsenic exposure mainly occurs in food materials through drinking water with high levels of arsenic in it. High levels of arsenic in groundwater have been found to be associated with various health-related problems including arsenicosis, skin lesions, cardiovascular diseases, reproductive problems, psychological, neurological, immunotoxic, and carcinogenesis. The mechanism of arsenic toxicity consists in its transformation in metaarsenite, which acylates protein sulfhydryl groups, affect on mitochondria by inhibiting succinic dehydrogenase activity and can uncouple oxidative phosphorylation with production of active oxygen species by tissues. A variety of dietary antioxidant supplements are useful to protect the carcinogenetic effects of arsenic. They play crucial role for counteracting oxidative damage and protect carcinogenesis by chelating with heavy metal moiety. Phytochemicals and chelating agents will be beneficial for combating heavy metal-induced carcinogenesis through its biopharmaceutical properties.

A perspective of chronic low exposure of arsenic on non-working women: Risk of hypertension

The relationship between arsenic (As) exposure and hypertension risk are extensively studied. The As content in scalp hair has been used as a reliable indicator of population for long-time exposure from different sources. Therefore, we investigated the association between hair As concentration and hypertension risk, as well as the potential modifying effects of single nucleotide polymorphisms (SNPs) related to phase II metabolism enzyme genes. We recruited 398 non-working women in Shanxi Province, northern China, from Aug 2012 to May 2013, including 163 subjects with hypertension (cases) and 235 healthy controls. Scalp hair and blood samples were collected from each subject. We analyzed the As concentrations of ~24-cm-long strands of hair representing the two most recent years of growth and SNPs of three genes (epoxide hydrolase 1, N-acetyltransferase 2, and glutathione S-transferase P1) in each subject. The results revealed that the hair As concentration of this population was significantly lower than in populations living near high As polluted sources in China and other countries. The median As concentration (inter-quartile range) of hair in the cases (i.e. 0.211 [0.114-0.395] μg/g hair) was higher than in the controls (i.e. 0.101 [0.048-0.227] μg/g hair). Higher hair As concentrations were associated with an elevated hypertension risk, with an adjusted odds ratio of 2.55 [95% confidence interval: 1.55-4.20]. No interaction effects between hair As concentration and SNPs related to phase II metabolism enzymes on hypertension risk were observed. It was concluded that chronic low exposure level of As might be associated with hypertension risk among the study subjects.

Chronic Exposure to Arsenic and Markers of Cardiometabolic Risk: A Cross-Sectional Study in Chihuahua, Mexico

BACKGROUND

Exposure to arsenic (As) concentrations in drinking water > 150 μg/L has been associated with risk of diabetes and cardiovascular disease, but little is known about the effects of lower exposures.

OBJECTIVE

This study aimed to examine whether moderate As exposure, or indicators of individual As metabolism at these levels of exposure, are associated with cardiometabolic risk.

METHODS

We analyzed cross-sectional associations between arsenic exposure and multiple markers of cardiometabolic risk using drinking-water As measurements and urinary As species data obtained from 1,160 adults in Chihuahua, Mexico, who were recruited in 2008-2013. Fasting blood glucose and lipid levels, the results of an oral glucose tolerance test, and blood pressure were used to characterize cardiometabolic risk. Multivariable logistic, multinomial, and linear regression were used to assess associations between cardiometabolic outcomes and water As or the sum of inorganic and methylated As species in urine.

RESULTS

After multivariable adjustment, concentrations in the second quartile of water As (25.5 to < 47.9 μg/L) and concentrations of total speciated urinary As (< 55.8 μg/L) below the median were significantly associated with elevated triglycerides, high total cholesterol, and diabetes. However, moderate water and urinary As levels were also positively associated with HDL cholesterol. Associations between arsenic exposure and both dysglycemia and triglyceridemia were higher among individuals with higher proportions of dimethylarsenic in urine.

CONCLUSIONS

Moderate exposure to As may increase cardiometabolic risk, particularly in individuals with high proportions of urinary dimethylarsenic. In this cohort, As exposure was associated with several markers of increased cardiometabolic risk (diabetes, triglyceridemia, and cholesterolemia), but exposure was also associated with higher rather than lower HDL cholesterol.

CITATION

Mendez MA, González-Horta C, Sánchez-Ramírez B, Ballinas-Casarrubias L, Hernández Cerón R, Viniegra Morales D, Baeza Terrazas FA, Ishida MC, Gutiérrez-Torres DS, Saunders RJ, Drobná Z, Fry RC, Buse JB, Loomis D, García-Vargas GG, Del Razo LM, Stýblo M. 2016. Chronic exposure to arsenic and markers of cardiometabolic risk: a cross-sectional study in Chihuahua, Mexico. Environ Health Perspect 124:104-111; http://dx.doi.org/10.1289/ehp.1408742.

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.

Clinical and biochemical characterization of high risk and not high risk for cardiovascular disease adults in a population from peripheral region of Bangladesh

Background

A group of 63708 Bangladeshi adults from a rural area were screened in 2011–12 for cardiovascular diseases (CVD) risk using a questionnaire based tool developed as part of the ‘WHO CVD-RISK Management Package for low-and medium resource setting’. In the current study participants who were found to be high risk and a sample of the not high risk participants from the screening were further characterized clinically and biochemically to explore the burden and determinants of CVD risk factors in a remote rural Bangladeshi population.

Methods

The high risk participants comprised all 1170 subjects who screened positive in 2011–12 and the not high risk group comprised 563 randomly sampled participants from the 62538 who screened negative. Socio-demographic, behavioral, anthropometric, clinical and biochemical data (glucose and lipids) were collected by standardized procedures. Body Mass Index (BMI) was classified following Asian BMI criteria. Data was analyzed using univariable and multivariable methods.

Results

On univariable analysis in high risk and not high risk participants respectively, age in years (M ± SD) was 50 ± 11 for both groups, ratio of male: female was 40:60 and 66:44, current smoking 28.5 % and 50.6 %; smokeless tobacco use 37.1 % and 34.8 %; overweight and obesity measured by body mass index (BMI) was 39.1 % and 20.5 %; high waist circumference (WC) 36.1 % and 11.9 %; high waist to hip ratio (WHR) 53.8 % and 26.3 %; and with high waist to height ratio (WHtR) 56.4 % and 28.4 %, existence of hypertension (HTN) was 15.8 % and 3.6 %, pre-HTN 43.8 % and 12.1 %, diabetes (DM) 14.0 % and 10.5 %, pre-DM 16.9 % and 12.1 % and dyslipidaemia 85.8 % and 89.5 %. In multivariable logistic regression analysis female sex, BMI, WC, WHR and WHtR, HTN and dyslipidaemia remain significantly more common among high risk participants (p < 0.05 and p < 0.001).

Conclusions

The prevalence of clinical and biochemical risk factors of CVDs are quite high even in this rural population and this may be related to the socioeconomic and cultural transition in Bangladeshi society. Surprisingly more of the high risk group was female and there were fewer smokers. Obesity and hypertension were more frequent in high risk participants.

Arsenic causes aortic dysfunction and systemic hypertension in rats: Augmentation of angiotensin II signaling

The groundwater pollutant arsenic can cause various cardiovascular disorders. Angiotensin II, a potent vasoconstrictor, plays an important role in vascular dysfunction by promoting changes in endothelial function, vascular reactivity, tissue remodeling and oxidative stress. We investigated whether modulation of angiotensin II signaling and redox homeostasis could be a mechanism contributing to arsenic-induced vascular disorder. Rats were exposed to arsenic at 25, 50 and 100ppm of sodium arsenite through drinking water consecutively for 90 days. Blood pressure was recorded weekly. On the 91st day, the rats were sacrificed for blood collection and isolation of thoracic aorta. Angiotensin converting enzyme and angiotensin II levels were assessed in plasma. Aortic reactivity to angiotensin II was assessed in organ-bath system. Western blot of AT1 receptors and G protein (Gαq/11), ELISA of signal transducers of MAP kinase pathway and reactive oxygen species (ROS) generation were assessed in aorta. Arsenic caused concentration-dependent increase in systolic, diastolic and mean arterial blood pressure from the 10th, 8th and 7th week onwards, respectively. Arsenic caused concentration-dependent enhancement of the angiotensin II-induced aortic contractile response. Arsenic also caused concentration-dependent increase in the plasma levels of angiotensin II and angiotensin converting enzyme and the expression of aortic AT1 receptor and Gαq/11 proteins. Arsenic increased aortic protein kinase C activity and the concentrations of protein tyrosine kinase, extracellular signal-regulated kinase-1/2 and vascular endothelial growth factor. Further, arsenic increased aortic mRNA expression of Nox2, Nox4 and p22phox, NADPH oxidase activity and ROS generation. The results suggest that arsenic-mediated enhancement of angiotensin II signaling could be an important mechanism in the arsenic-induced vascular disorder, where ROS could augment the angiotensin II signaling through activation of MAP kinase pathway.

The health effects of exposure to arsenic-contaminated drinking water: a review by global geographical distribution

Chronic arsenic exposure through drinking water has been a vigorously studied and debated subject. However, the existing literature does not allow for a thorough examination of the potential regional discrepancies that may arise among arsenic-related health outcomes. The purpose of this article is to provide an updated review of the literature on arsenic exposure and commonly discussed health effects according to global geographical distribution. This geographically segmented approach helps uncover the discrepancies in the health effects of arsenic. For instance, women are more susceptible than men to a few types of cancer in Taiwan, but not in other countries. Although skin cancer and arsenic exposure correlations have been discovered in Chile, Argentina, the United States, and Taiwan, no evident association was found in mainland China. We then propose several globally applicable recommendations to prevent and treat the further spread of arsenic poisoning and suggestions of future study designs and decision-making.

Embryonic exposure to sodium arsenite perturbs vascular development in zebrafish

Exposure to arsenic in its inorganic form, arsenite, causes adverse effects to many different organs and tissues. Here, we have investigated arsenite-induced adverse effects on vascular tissues in the model organism zebrafish, Danio rerio. Zebrafish embryos were exposed to arsenite at different exposure windows and the susceptibility to vascular tissue damage was recorded at 72hours post fertilization (hpf). Intersegmental vessel sprouting and growth was most perturbed by exposure to arsenite during the 24-48hpf window, while disruption in the condensation of the caudal vein plexus was more often observed at the 48-72hpf exposure window, reflecting when these structures develop during normal embryogenesis. The vascular growth rate was decreased by arsenite exposure, and deviated from that of control embryos at around 24-26.5hpf. We further mapped changes in expression of key regulators of angiogenesis and vasculogenesis. Downregulation of vascular endothelial growth factor receptor 1/fms-related tyrosine kinase 1 (vegfr1/flt1) expression was evident already at 24hpf, coinciding with the decreased vascular growth rate. At later time points, matrix metalloproteinase 9 (mmp9) expression was upregulated, suggesting that arsenite affects the composition of the extracellular matrix. In total, the expression of eight key factors involved in different aspects of vascularization was significantly altered by arsenic exposure. In conclusion, our results show that arsenite is a potent vascular disruptor in the developing zebrafish embryo, a finding that calls for an evaluation of arsenite as a developmental vascular toxicant in mammalian model systems.

Arsenic exposure decreases rhythmic contractions of vascular tone through sodium transporters and K+ channels

Arsenic-contaminated drinking water is a public health problem in countries such as Taiwan, Bangladesh, United States, Mexico, Argentina, and Chile. The chronic ingestion of arsenic-contaminated drinking water increases the risk for ischemic heart disease, cerebrovascular disease, and prevalence of hypertension. Although toxic arsenic effects are controversial, there is evidence that a high concentration of arsenic may induce hypertension through increase in vascular tone and resistance. Vascular tone is regulated by the rhythmic contractions of the blood vessels, generated by calcium oscillations in the cytosol of vascular smooth muscle cells. To regulate the cytosolic calcium oscillations, the membrane oscillator model involves the participation of Ca²⁺ channels, calcium-activated K⁺ channels, Na⁺/Ca²⁺ exchange, plasma membrane Ca²⁺-ATPase, and the Na⁺/K⁺-ATPase. However, little is known about the role of K⁺ uptake by sodium transporters [Na⁺/K⁺-ATPase or Na⁺-K⁺-2Cl^- (NKCC1)] on the rhythmic contractions. Vascular rhythmic contractions, or vasomotion are a local mechanism to regulate vascular resistance and blood flow. Since vascular rhythmic contractions of blood vessels are involved in modulating the vascular resistance, the blood flow, and the systemic pressure, we suggest a model explaining the participation of the sodium pump and NKCC1 co-transporter in low dose arsenic exposure effects on vasomotion and vascular dysfunction.

Analysis of the spatial variation of hospitalization admissions for hypertension disease in Shenzhen, China

In China, awareness about hypertension, the treatment rate and the control rate are low compared to developed countries, even though China's aging population has grown, especially in those areas with a high degree of urbanization. However, limited epidemiological studies have attempted to describe the spatial variation of the geo-referenced data on hypertension disease over an urban area of China. In this study, we applied hierarchical Bayesian models to explore the spatial heterogeneity of the relative risk for hypertension admissions throughout Shenzhen in 2011. The final model specification includes an intercept and spatial components (structured and unstructured). Although the road density could be used as a covariate in modeling, it is an indirect factor on the relative risk. In addition, spatial scan statistics and spatial analysis were utilized to identify the spatial pattern and to map the clusters. The results showed that the relative risk for hospital admission for hypertension has high-value clusters in the south and southeastern Shenzhen. This study aimed to identify some specific regions with high relative risk, and this information is useful for the health administrators. Further research should address more-detailed data collection and an explanation of the spatial patterns.