Arsenic Exposure in Relation to Ischemic Stroke: The Reasons for Geographic and Racial Differences in Stroke Study

Association Between Blood Selenium Levels and Stroke: A Study Based on the NHANES (2011-2018)

At present, the association between circulating selenium and stroke is still in dispute. Thus, this study aimed to ascertain the association with a larger sample size than the previous study, based on the National Health and Nutrition Examination Survey (NHANES) from 2011 to 2018. In total, 13755 adults over the age of 20 years were included in our study. Multivariate logistic regression models were applied to analyze the correlation between blood selenium levels and stroke. The smooth curve fitting was performed to test the dose-response effects between blood selenium levels and stroke. After adjusting for all confounders, blood selenium levels were negatively associated with stroke (odds ratio [OR] = 0.57, 95% confidence interval [CI]: 0.37-0.87, P = 0.014). In the fully adjusted model, the highest tertile of blood selenium levels was negatively associated with stroke compared with the lowest tertile (OR = 0.70, 95% CI: 0.53-0.93, P for trend = 0.016). Moreover, the relationship between blood selenium levels and stroke was linear. In subgroup analyses, we observed that the test for interactions was significant for body mass index (BMI) and uric acid (P for interaction < 0.05). The negative relationship was stronger in participants with BMI 25-30 kg/m2 (OR = 0.23, 95% CI: 0.13-0.44, P < 0.001). Therefore, in American adults, the relationship between blood selenium levels and stroke was negative, with a linear tendency. In the future, a cohort study is warranted to further confirm this relationship.

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.

Association between serum copper levels and stroke in the general population: A nationally representative study

OBJECTIVES

The objective was to explore the association between serum copper levels and the prevalence of stroke.

METHODS

Data were obtained from 3 consecutive National Health and Nutrition Examination Survey (NHANES) cycles (2011-2016). Weighted multivariable logistic regression analysis was conducted to evaluate the association between serum copper levels and self-reported stroke.

RESULTS

A total of 5,151 adults met the inclusion criteria. A total of 181 (3.51%) stroke patients were identified. In comparison to individuals with serum copper levels in the lowest tertile (<16.4 µmol/l), those with levels in the middle tertile (16.4-19.8 µmol/l) had an odds ratio (OR) of 0.99 (95% confidence interval [CI]: 0.44-2.25), while those with levels in the highest tertile (>19.8 µmol/l) had an OR of 2.36 (95% CI: 1.01-5.52). Furthermore, each standard deviation (SD) increase in serum copper was found to be positively associated with the prevalence of stroke, with an OR of 1.44 (95% CI: 1.11-1.86). Dose‒response analysis showed a positive linear association between serum copper levels and stroke (Pnonlinearity=0.554).

CONCLUSIONS

This cross-sectional study suggested a positive association between serum copper levels and stroke among American adults.

Occupational Risk Factors for Stroke: A Comprehensive Review

For primary prevention, it is important for public health and clinical medicine to identify and characterize modifiable risk factors of stroke. In existing literature, the impact of occupational variables on ischemic and hemorrhagic stroke has been extensively studied. This review summarizes the available data on the significance of occupational variables in stroke. The results of this review suggest that there is sufficient evidence for the relationship between increased risk of stroke and job stress, working in extreme temperatures, long working hours, and/or shift work. The association between long working hours and occupational exposure to noise and chemicals remains inconclusive although several studies have reported this finding. This review will act as a step toward future research and provide information that may serve as a baseline for developing targeted interventions to prevent stroke in the working population.

Metals in Alzheimer's Disease

The role of metals in the pathogenesis of Alzheimer's disease (AD) is still debated. Although previous research has linked changes in essential metal homeostasis and exposure to environmental heavy metals to the pathogenesis of AD, more research is needed to determine the relationship between metals and AD. In this review, we included human studies that (1) compared the metal concentrations between AD patients and healthy controls, (2) correlated concentrations of AD cerebrospinal fluid (CSF) biomarkers with metal concentrations, and (3) used Mendelian randomization (MR) to assess the potential metal contributions to AD risk. Although many studies have examined various metals in dementia patients, understanding the dynamics of metals in these patients remains difficult due to considerable inconsistencies among the results of individual studies. The most consistent findings were for Zn and Cu, with most studies observing a decrease in Zn levels and an increase in Cu levels in AD patients. However, several studies found no such relation. Because few studies have compared metal levels with biomarker levels in the CSF of AD patients, more research of this type is required. Given that MR is revolutionizing epidemiologic research, additional MR studies that include participants from diverse ethnic backgrounds to assess the causal relationship between metals and AD risk are critical.

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.

Environmental toxic metal contaminants and risk of stroke: a systematic review and meta-analysis

The relationship between toxic metals in the environment and clinical stroke risk remains unclear, although their role as immunotoxicants and carcinogens has been well established. We conducted a systematic review of the relationship between five metals (arsenic, mercury, copper, cadmium, and lead) and stroke. First, we comprehensively searched 3 databases (Pubmed, EMBASE, and Cochrane) from inception until June 2021. Random-effects meta-analyses, pooled relative risks (RR) and 95% confidence intervals (CI) were applied to evaluate the effect value. We finally identified 38 studies involving 642,014 non-overlapping participants. Comparing the highest vs. lowest baseline levels, chronic exposure to lead (RR = 1.07; 95%CI,1.00-1.14), cadmium (RR = 1.30; 95%CI,1.13-1.48), and copper (RR = 1.19; 95%CI,1.04-1.36) were significantly associated with stroke risks. However, the other two metals (arsenic and mercury) had less effect on stroke risk. Further analysis indicated that the association was likely in a metal dose-dependent manner. The results may further support the possibility that environmental toxic metal contaminants in recent years are associated with the increased risk of stroke.

Pentoxifylline Attenuates Arsenic Trioxide-Induced Cardiac Oxidative Damage in Mice

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

Association of low-level inorganic arsenic exposure from rice with age-standardized mortality risk of cardiovascular disease (CVD) in England and Wales

Adverse health outcomes, including death from cardiovascular disease (CVD), arising from chronic exposure to inorganic arsenic (iAs) are well documented. Consumption of rice is a major iAs exposure route for over 3 billion people, however, there is still a lack of epidemiological evidence demonstrating the association between iAs exposure from rice intake and CVD risks. We explored this potential association through an ecological study using data at local authority level across England and Wales. Local authority level daily per capita iAs exposure from rice (E-iAs_ing,rice) was estimated using ethnicity as a proxy for class of rice consumption. A series of linear and non-linear models were applied to estimate the association between E-iAs_ing,rice and CVD age-standardized mortality rate (ASMR), using Akaike's Information Criterion as the principle model selection criterion. When adjusted for significant confounders, notably smoking prevalence, education level, employment rate, overweight percentage, PM2.5, female percentage and medical and care establishments, the preferred non-linear model indicated that CVD risks increased with iAs exposure from rice at exposures above 0.3 μg/person/day. Also, the best-fitted linear model indicated that CVD ASMR in the highest quartile of iAs exposure (0.375-2.71 μg/person/day) was 1.06 (1.02, 1.11; p-trend <0.001) times higher than that in the lowest quartile (<0.265 μg/person/day). Notwithstanding the well-known limitations of ecological studies, this study further suggests exposure to iAs, including from rice intake, as a potentially important confounder for studies of the factors controlling CVD risks.

Association between Heavy Metals and Rare Earth Elements with Acute Ischemic Stroke: A Case-Control Study Conducted in the Canary Islands (Spain)

The role of inorganic elements as risk factors for stroke has been suggested. We designed a case-control study to explore the role of 45 inorganic elements as factors associated with stroke in 92 patients and 83 controls. Nineteen elements were detected in >80% of patients and 21 were detected in >80% of controls. Blood level of lead was significantly higher among patients (11.2 vs. 9.03 ng/mL) while gold and cerium were significantly higher among controls (0.013 vs. 0.007 ng/mL; and 18.0 vs. 15.0 ng/mL). Lead was associated with stroke in univariate and multivariate analysis (OR = 1.65 (95% CI, 1.09–2.50) and OR = 1.91 (95% CI, 1.20–3.04), respectively). Gold and cerium showed an inverse association with stroke in multivariate analysis (OR = 0.81 (95% CI, 0.69–0.95) and OR = 0.50 (95% CI, 0.31–0.78)). Future studies are needed to elucidate the potential sources of exposure and disclose the mechanisms of action.

Heavy Metal-Induced Cerebral Small Vessel Disease: Insights into Molecular Mechanisms and Possible Reversal Strategies

Heavy metals are considered a continuous threat to humanity, as they cannot be eradicated. Prolonged exposure to heavy metals/metalloids in humans has been associated with several health risks, including neurodegeneration, vascular dysfunction, metabolic disorders, cancer, etc. Small blood vessels are highly vulnerable to heavy metals as they are directly exposed to the blood circulatory system, which has comparatively higher concentration of heavy metals than other organs. Cerebral small vessel disease (CSVD) is an umbrella term used to describe various pathological processes that affect the cerebral small blood vessels and is accepted as a primary contributor in associated disorders, such as dementia, cognitive disabilities, mood disorder, and ischemic, as well as a hemorrhagic stroke. In this review, we discuss the possible implication of heavy metals/metalloid exposure in CSVD and its associated disorders based on in-vitro, preclinical, and clinical evidences. We briefly discuss the CSVD, prevalence, epidemiology, and risk factors for development such as genetic, traditional, and environmental factors. Toxic effects of specific heavy metal/metalloid intoxication (As, Cd, Pb, Hg, and Cu) in the small vessel associated endothelium and vascular dysfunction too have been reviewed. An attempt has been made to highlight the possible molecular mechanism involved in the pathophysiology, such as oxidative stress, inflammatory pathway, matrix metalloproteinases (MMPs) expression, and amyloid angiopathy in the CSVD and related disorders. Finally, we discussed the role of cellular antioxidant defense enzymes to neutralize the toxic effect, and also highlighted the potential reversal strategies to combat heavy metal-induced vascular changes. In conclusion, heavy metals in small vessels are strongly associated with the development as well as the progression of CSVD. Chelation therapy may be an effective strategy to reduce the toxic metal load and the associated complications.

Positive association between soil arsenic concentration and mortality from alzheimer's disease in mainland China

OBJECTIVES

The current study was designed to investigate the relationship between the soil arsenic (As) concentration and the mortality from Alzheimer's disease (AD) in mainland China.

STUDY DESIGN

Ecological study.

METHODS

Twenty-two provinces and 3 municipal districts in mainland China were included in this study. The As concentrations in soil in 1990 was obtained from the China State Environmental Protection Bureau; the data on annual mortality of AD from 1991 to 2000 were obtained from the National Death Cause Surveillance Database of China. Using these data, we calculated the spearman correlation coefficient between soil As concentration and AD mortality, and the relative risk (RR) between soil As levels and AD mortality by quartile-dividing study groups.

RESULTS

The spearman correlation coefficient between As concentration and AD mortality was 0.552 (p = 0.004), 0.616 (p = 0.001) and 0.622 (p = 0.001) in the A soil As (eluvial horizon), the C soil As (parent material horizon), and the Total soil As (A soil As + C soil As), respectively. When the A soil As concentration was over 9.05 mg/kg, 10.40 mg/kg and 13.10 mg/kg, the relative risk was 0.835 (95 % CI: 0.832, 0.838), 1.969 (95 %CI: 1.955, 1.982), and 2.939 (95 % CI: 2.920, 2.958), respectively; when the C soil As reached 9.45 mg/kg, 11.10 mg/kg and 13.55 mg/kg, the relative risk was 4.349 (95 % CI: 4.303, 4.396), 6.108 (95 % CI: 6.044, 6.172), and 9.125 (95 %CI: 9.033, 9.219), respectively. No correlation was found between lead, cadmium, and mercury concentration in the soil and AD mortality.

CONCLUSION

There was an apparent soil As concentration dependent increase in AD mortality. Results of this study may provide evidence for a possible causal linkage between arsenic exposure and the death risk from AD.

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.

Associations of multiple plasma metals with the risk of ischemic stroke: A case-control study

BACKGROUND

Ischemic stroke (IS) is a major cause of morbidity and mortality globally. Environmental exposure to metals may be linked to the risk of IS, but the association remains uncertain in Chinese populations.

OBJECTIVES

The present study aimed to examine the associations between the concentrations of 11 metals (aluminum, arsenic, cadmium, cobalt, copper, iron, manganese, molybdenum, selenium, thallium, and zinc) in plasma and the risk of IS in a Chinese population.

METHODS

A total of 1277 pairs of newly diagnosed IS patients and controls matched on age (±3 years) and sex were recruited in our study. Plasma metal concentrations were measured using inductively coupled plasma mass spectrometry. Multivariable conditional logistic regression models were conducted to investigate the impacts of single and multiple metals, respectively.

RESULTS

In the single-metal model, exposure to seven metals (aluminum, arsenic, cadmium, cobalt, iron, manganese and selenium) was individually associated with the risk of IS based on the trend test. Further stepwise regression analyses with the multiple-metal model revealed increasing trends in the risk of IS associated with aluminum, arsenic, and cadmium quartiles and decreasing trends with iron and selenium quartiles (p-trend < 0.01). Compared to the lowest quartiles, the odds ratios (95% confidence intervals) for the highest quartiles of these five metals were 4.23 (2.63, 6.79), 1.88 (1.25, 2.81), 5.02 (3.30, 7.63), 0.59 (0.40, 0.89), and 0.10 (0.06, 0.17), respectively.

CONCLUSIONS

Our study suggested that higher plasma concentrations of aluminum, arsenic, and cadmium, and lower concentrations of iron and selenium may increase the risk of IS. Further prospective studies in larger populations are warranted to confirm our findings.

Low-level exposure to arsenic in drinking water and incidence rate of stroke: A cohort study in Denmark

INTRODUCTION

High arsenic concentration in drinking water is associated with a higher incidence rate of stroke, but only few studies have investigated an association with arsenic in drinking water at low concentration (<50 μg/L).

OBJECTIVE

To examine if arsenic in drinking water at low concentration was associated with higher incidence rate of stroke in Denmark.

METHODS

A total of 57,053 individuals from the Danish Diet, Cancer, and Health cohort was included in the study (enrolment in 1993-1997, age 50-64 years), of which 2195 individuals had incident stroke between enrolment and November 2009. Individuals were enrolled in two major cities (Copenhagen and Aarhus). Residential addresses in the period 1973-2009 were geocoded and arsenic concentration in drinking water at each address was estimated by linking addresses with water supply areas. Associations between arsenic concentration and incidence rate of stroke were analysed using a generalized linear model with a Poisson distribution. Incidence rate ratios (IRR) were adjusted for differences in age, sex, calendar-year, lifestyle factors, and educational level.

RESULTS

Median arsenic concentration in drinking water was 0.7 μg/L at enrolment addresses (range: 0.03 to 25 μg/L), with highest concentrations in the Aarhus area. The adjusted IRRs were 1.17 (95% CI: 1.04-1.32) for the highest arsenic quartile (1.93-25.3 μg/L) when compared with the lowest quartile (0.049-0.57 μg/L), but the highest IRR was seen in the second quartile (0.57-0.76 μg/L) (IRR = 1.21; 95% CI: 1.07-1.36). The highest IRR in the upper quartile was seen in the Aarhus area (IRR = 1.79; 95% CI: 1.41-2.26). Having ever been exposed to10 μg/L or more arsenic in drinking water resulted in an IRR at 1.44 (95% CI: 1.00-2.08) for all strokes and 1.63 (95% CI: 1.11-2.39) for ischemic strokes.

CONCLUSION

The results indicate that arsenic in drinking water even at low concentration is associated with higher incidence rate of stroke.

Urinary cadmium concentration and the risk of ischemic stroke

OBJECTIVES

To examine the association between urinary cadmium levels and the incidence of ischemic stroke and to explore possible effect modifications.

METHODS

A case-cohort study was designed nested in the Reasons for Geographic and Racial Differences in Stroke (REGARDS) study, including 680 adjudicated incident cases of ischemic stroke and 2,540 participants in a randomly selected subcohort. Urinary creatinine-corrected cadmium concentration was measured at baseline. Multivariable-adjusted hazard ratios (HRs) and the corresponding 95% confidence intervals (CIs) were estimated with the Barlow weighting method for the Cox proportional hazards regression model.

RESULTS

The median urinary cadmium concentration was 0.42 (interquartile range 0.27-0.68) μg/g creatinine. After adjustment for potential confounders, urinary cadmium was associated with increased incidence of ischemic stroke (quintile 5 vs quintile 1: HR 1.50, 95% CI 1.01-2.22, p for trend = 0.02). The observed association was more pronounced among participants in the lowest serum zinc tertile (tertile 3 vs tertile 1: HR 1.82, 95% CI 1.06-3.11, p for trend = 0.004, p for interaction = 0.05) but was attenuated and became nonsignificant among never smokers (tertile 3 vs tertile 1: never smokers: HR 1.27, 95% CI 0.80-2.03, p for trend = 0.29; ever smokers: HR 1.60, 95% CI 1.06-2.43, p for trend = 0.07, p for interaction = 0.51).

CONCLUSIONS

Findings from this study suggest that cadmium exposure may be an independent risk factor for ischemic stroke in the US general population. Never smoking and maintaining a high serum zinc level may ameliorate the potential adverse effects of cadmium exposure.