The association between arsenic exposure from drinking water and cerebrovascular disease mortality in Taiwan

Bioaccumulation and sources of metal(loid)s in fish species from a subtropical river in Bangladesh: a public health concern

Toxic metals and freshwater fish's metalloid contamination are significant environmental concerns for overall public health. However, the bioaccumulation and sources of metal(loids) in freshwater fishes from Bangladesh still remain unknown. Thus, the As, Pb, Cd, and Cr concentrations in various freshwater fish species from the Rupsha River basin were measured, including Tenualosa ilisha, Gudusia chapra, Otolithoides pama, Setipinna phasa, Mystus vittatus, Glossogobius giuris, and Pseudeutropius atherinoides. An atomic absorption spectrophotometer was used to determine metal concentrations. The mean concentrations of metal(loids) in the fish muscle (mg/kg) were found to be As (1.53) > Pb (1.25) > Cr (0.51) > Cd (0.39) in summer and As (1.72) > Pb (1.51) > Cr (0.65) > Cd (0.49) in winter. The analyzed fish species had considerably different metal(loid) concentrations with seasonal variation, and the distribution of the metals (loids) was consistent with the normal distribution. The demersal species, M. vittatus, displayed the highest bio-accumulative value over the summer. However, in both seasons, none of the species were bio-accumulative. According to multivariate statistical findings, the research area's potential sources of metal(loid) were anthropogenic activities linked to geogenic processes. Estimated daily intake, target hazard quotient (THQ), and carcinogenic risk (CR) were used to assess the influence of the risk on human health. The consumers' THQs values were < 1, indicating that there were no non-carcinogenic concerns for local consumers. Both categories of customers had CRs that fell below the permissible range of 1E - 6 to 1E - 4, meaning they were not at any increased risk of developing cancer. The children's group was more vulnerable to both carcinogenic and non-carcinogenic hazards. Therefore, the entry of metal(loids) must be regulated, and appropriate laws must be used by policymakers.

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.

Influence of humic acid and fluvic acid on the altered toxicities of arsenite and arsenate toward two freshwater algae

Arsenic pollution in freshwater poses a serious threat to aquatic organisms. However, dissolved organic matter (DOM) in water can modulate arsenic environmental toxicity by either suppressing or promoting its bioaccumulation. In this study, we investigated the toxicity, bioaccumulation, and biotransformation of inorganic arsenic (arsenite As^III and arsenate As^V) combined with two types of DOM, i.e., humic acid (HA) and fulvic acid (FA), in the algae Chlamydomonas reinhardtii and Ochromonas danica. C. reinhardtii has a cell wall and cannot bioaccumulate arsenic complexation, whereas O. danica has no cell wall. Without DOM, As^V was more toxic than As^III for C. reinhardtii, and As^V was less toxic than As^III for O. danica. HA and FA addition reduced As^V and As^III toxicities; the larger molecular weight (M_w) of HA contributed to the reduction in toxicity to an even greater extent, and reduced arsenic accumulation while promoting the biotransformation ability of C. reinhardtii, which has a cell wall. However, HA and FA addition increased As^V and As^III toxicities and arsenic accumulation while relatively enhancing the biotransformation ability of O. danica, which has no cell wall. Coupling toxicity, bioaccumulation, and biotransformation, DOM (HA and FA) contributed to the altered toxicity of freshwater algae to As^V and As^III through reduced/increased arsenic accumulation and enhanced biotransformation. Overall, our study considered the combined toxicity of inorganic arsenic and DOM in phytoplankton, helping estimate the potential environmental risk of arsenic in aqueous environments.

The gut microbiome and arsenic-induced disease-iAs metabolism in mice

PURPOSE OF REVIEW

This review summarizes inorganic arsenic (iAs) metabolism and toxicity in mice and the gut microbiome and how iAs and the gut microbiome interact to induce diseases.

RECENT FINDINGS

Recently, a variety of studies have started to reveal the interactions between iAs and the gut microbiome. Evidence shows that gut bacteria can influence iAs biotransformation and disease risks. The gut microbiome can directly metabolize iAs, and it can also indirectly be involved in iAs metabolism through the host, such as altering iAs absorption, cofactors, and genes related to iAs metabolism. Many factors, such as iAs metabolism influenced by the gut microbiome, and microbiome metabolites perturbed by iAs can lead to different disease risks. iAs is a widespread toxic metalloid in environment, and iAs toxicity has become a global health issue. iAs is subject to metabolic reactions after entering the host body, including methylation, demethylation, oxidation, reduction, and thiolation. Different arsenic species, including trivalent and pentavalent forms and inorganic and organic forms, determine their toxicity. iAs poisoning is predominately caused by contaminated drinking water and food, and chronic arsenic toxicity can cause various diseases. Therefore, studies of iAs metabolism are important for understanding iAs associated disease risks.

Challenges for Safe and Healthy Drinking Water in China

PURPOSE OF REVIEW

Rapid economic growth and its huge population are putting tremendous pressure on water sustainability in China. Ensuring clean drinking water is a great challenge for public health due to water shortage and pollution. This article reviews current scientific findings on health-related issues on drinking water and discusses the challenges for safe and healthy drinking water in China.

RECENT FINDINGS

From literature published since 2010, a variety of emerging contaminants were detected in drinking water, including disinfection byproducts (DBPs), pharmaceuticals and personal care products (PPCPs), endocrine-disrupting compounds (EDCs), antibiotic resistance genes, and pathogens. Arsenic and fluoride are still the two major contaminants in groundwater. Microcystins, toxins produced by cyanobacteria, were also frequently detected in surface water for drinking. Health effects of exposure to arsenic, fluoride, nitrates, DBPs, and noroviruses in drinking water have been reported in several epidemiological studies. According to literature, water scarcity is still a severe ongoing issue, and regional disparity affects the access to safe and healthy drinking water. In addition, urbanization and climate change have strong influences on drinking water quality and water quantity. Multiple classes of contaminants of emerging concern have been detected in drinking water, while epidemiological studies on their health effects are still inadequate. Water scarcity, regional disparity, urbanization, and climate change are the major challenges for safe and healthy drinking water in China.

Study of Toxicity Assessment of Heavy Metals from Steel Slag and Its Asphalt Mixture

Steel slag has been used widely as an aggregate in road application, but it could pose a contamination risk for the environment due to considerable heavy metals (HMs). To explore the leaching behavior and contamination risk of HMs from steel slag and its asphalt mixture is of great significance. In this study, the physical-chemical features, batch leaching test and semi-dynamic test were conducted to determine the mobility capability and leaching characteristics of HMs. The results show that steel slag presents a low pollution risk in short-term leaching, whereas the cumulative release mass of Cd, Ni, As and Pb are more than or approach the limits, which indicates that steel slag exhibits environment impacts to a certain extent. Steel slag covered with asphalt binder results in As and Cu reduced by 3.64% and 4.83%. Diffusion is the main controlling mechanism of HMs in asphalt mixture and the mobility capability of most HMs were classed as “low mobility” (LI > 8). Asphalt stripping off can aggravate the release potential of HMs from asphalt mixture, but the pollution risk remains controllable.

Bioaccumulation and heavy metal concentration in tissues of some commercial fishes from the Meghna River Estuary in Bangladesh and human health implications

Despite the beneficial aspect of aquatic food's consumption, bioaccumulation of toxic metals in fish can enhance the health risk for the consumers. Heavy metals were measured from editable tissues of some commercial fish species like Latis calcarifer, Silonia silondia, Clupisoma garua, Planiliza subviridis, Otolithoides pama, Tenulosa ilisa, Rhinomugil corsula, and Aila coila in the Meghna river estuary in Noakhali district. Heavy metals such as As, Pb, Cd, Cu, and Cr were detected by ICP-MS, which were significantly different (p ≤ 0.01), and the hierarchy of all mean concentrations were: Cu (5.14 mg/kg) > Pb (3.79 mg/kg) > As (1.08 mg/kg) > Cr (0.78 mg/kg) > Cd (0.12 mg/kg). The mean concentration of Cu (6.62 mg/kg) imparted to the maximum level in L. calcarifer, which slightly exceeded the Bangladesh food safety guideline. The mean BAFs of the contaminants were found as: Pb (1042.29) > Cr (1036.47) > As (934.84) > Cd (832.77) > Cu (772). Further, L. calcarifer, S. silondia, C. garua, and P. subviridis showed the bioaccumulative status. To assess the health risk effects, estimated daily intake (EDI), target hazard quotient (THQ) and carcinogenic risk (CR) were conducted. THQs for both adult and children consumers were <1, indicating that, consumers would not experience the non-carcinogenic health effects. Although children were more susceptible than adults, CR for all the consumers was found in the acceptable range (10^-6 to 10^-4).

High arsenic groundwater in the Guide basin, northwestern China: Distribution and genesis mechanisms

High arsenic (As) groundwater has been found in Pliocene confined aquifers at depths from 100 to 300 m of the Guide basin, but little is known on the main hydrogeochemical processes leading to its elevated concentrations. Ninety-seven water samples and fifty-three sediment samples were collected for chemical and/or isotopic analysis. Concentrations of As in groundwater of confined aquifer range from 9.9 to 377 μg/L (average 109 μg/L), which generally show a sharply increasing trend along with NH₄⁺, HCO₃^-, CO₃^2- and TOC along the inferred flow path, while NO₃^-, SO₄^2-/Cl^- and redox potential (Eh) have decreasing trends. Results of sequential extraction show that As bound to amorphous and crystalline Fe oxide minerals are the main As forms, accounting for around 50% of total As in sediments. Reductive dissolution of As-bearing Fe(III) oxide minerals under reducing conditions in confined aquifers lead to the mobilization of As in groundwater. In addition, alkaline environment and high concentrations of HCO₃^- and CO₃^2- may make contributions to As enrichment in groundwater. High As groundwater in confined aquifer continuously flows out on the ground surface through tens of artesian wells, which may potentially contaminate low As groundwater in unconfined aquifer. Thus, further investigation is needed to evaluate long-term variations of water chemistry of low As groundwater and assess vulnerability of unconfined aquifer to As contamination.

Sneaky Entry of IFNγ Through Arsenic-Induced Leaky Blood-Brain Barrier Reduces CD200 Expression by Microglial pro-Inflammatory Cytokine

Recent studies showed that neuronal surface protein CD200 plays a key role in the regulation of neuroinflammation. Previously, we showed that arsenic (0.38 mg/kg body weight) exposure induces microglial activation and consequently IL-6/TNF-α secretion. This result indicated the possibility of alteration in the expression of CD200. Therefore, the present study was focused on checking arsenic-induced alteration in CD200 expression and revealing the underlying mechanism. Male BALB/c mice were exposed to arsenic (vehicle, 0.038 and 0.38 mg/kg body weight) for 60 days, and the expression level of CD200 was found to be decreased which was rescued by minocycline (33 mg/kg body weight) co-administration. Higher CD68 staining, increased level of IL-6/TNF-α, as well as higher level of IFNγ, were observed in in vivo arsenic-exposed groups. Interestingly, in vitro arsenic exposure could not increase IL-6/TNF-α level in the culture supernatant, whereas, supplementation of IFNγ could mimic the in vivo results. However, arsenic could not induce IFNγ production from brain endothelial cells, microglia, and astrocytes, thereby suggesting the entry of IFNγ through the impaired blood-brain barrier. Evans blue fluorescence in the brain confirms altered blood-brain barrier permeability although no changes were observed in the expression level of tight junction proteins (claudin-5 and occludin). Finally, intracerebral injection of anti-IFNγ neutralizing antibody in arsenic-exposed brain reduced microglia activation (IL-6 and TNF-α and CD68 expression) and subsequently rescued CD200 level. Taken together, the study showed that arsenic-mediated compromised blood-brain barrier is a major driving force to induce microglial IL-6 and TNF-α production through serum IFNγ leading to CD200 downregulation.

Associations between arsenic in drinking water and occurrence of end-stage renal disease with modifications by comorbidities: A nationwide population-based study in Taiwan

Arsenic may affect the function of proximal convoluted tubules and glomeruli, but epidemiological data on the association between arsenic ingestion and end-stage renal disease (ESRD) are limited. Therefore, we conducted a nationwide population-based study in Taiwan, where the incidence of ESRD is the highest in the world, to study the potential association. Using the National Health Insurance Database in Taiwan, we constructed a cohort of 362,505 members with age≥40years in 1998. We identified patients of ESRD newly diagnosed between January 1, 1998 and December 31, 2010 and performed Cox proportional hazard regressions to identify risk factors for ESRD and evaluate their effects. Arsenic levels in drinking water were assessed on the basis of a nationwide census survey conducted by the government, of which measurement reports were available for 311 townships. We identified 5442 new patient of ESRD during the study period and found that residents of areas with arsenic levels≥50μg/L in the drinking water had a hazard ratio (HR) of 1.14 (95% confidence interval [CI]: 1.08-1.21) for ESRD. After adjusting for sex, age, income, and comorbidities, we found an adjusted HR of 1.12 (95% CI: 1.06-1.19), which was still statistically significant. Furthermore, the effect was modified by comorbidities, with more prominent effects on patients with less than three comorbidities (adjusted HR=1.51; 95% CI: 1.22-1.86 for low comorbidity score). In conclusion, a high arsenic level in drinking water was a risk factor for ESRD, independent of other documented risk factors. Reducing high-risk comorbidities in patients with early-stage renal dysfunction is important for slowing the progression of the disease to ESRD, even in the endemic area of arsenic exposure.

Concentration and potential health risk of heavy metals in seafoods collected from Sanmen Bay and its adjacent areas, China

Commercial marine fish, crustacean, and mollusc samples were collected from Sanmen Bay and its adjacent areas to investigate the accumulation of heavy metals in various species of marine organisms and evaluate the potential health risk for local consumers. The results indicated significant variations in metal contents among species. The highest concentrations of studied metals were found in molluscs, followed by crustaceans and fish. The first metal group of arsenic (As), cadmium, copper, and zinc were associated by their relatively high concentrations in the tissues of marine organisms, whereas chromium, mercury, and lead were identified the other group with low concentrations. Human health risk evaluation indicated that the exposure doses of most elements for coastal people were safe, except for As, which scored a high total target hazard quotient and target cancer risk value. Potential health risk of heavy metal exposure from seafood consumption should not be ignored.

Associations between urinary total arsenic levels, fetal development, and neonatal birth outcomes: A cohort study in Taiwan

BACKGROUND

Arsenic exposure is a global health concern. Several studies have focused on chronic arsenic exposure in adults; however, limited data are available regarding the potential adverse effects of prenatal exposure on fetuses and neonates.

OBJECTIVES

To assess which time point maternal arsenic exposure may influence the fetus during pregnancy and birth outcomes.

METHODS

In this study, total arsenic concentrations were analyzed in urine samples collected from 130 women with singleton pregnancies (22-45years old) in Taiwan from March to December of 2010. All fetal biometric measurements in each trimester period and birth outcomes at delivery were obtained. We applied a generalized estimating equation model and multivariate regression models to evaluate the associations between maternal urinary total arsenic (UtAs) exposure during pregnancy, fetal biometric measurements, and neonatal birth outcomes.

RESULTS

We observed statistically significant correlations between maternal UtAs levels and the fetal biparietal diameter over all three trimesters (β=-1.046mm, p<0.05). Multiple regression analyses showed a negative association between maternal UtAs levels and chest circumference in the first trimester (β=-0.721cm, p<0.05), and second-trimester UtAs exposure was associated with decreases in birth weight (β=-173.26g, p<0.01), head circumference (β=-0.611cm, p<0.05), and chest circumference (β=-0.654cm, p<0.05). Dose-response relationships were also observed for maternal UtAs exposure and birth outcomes.

CONCLUSIONS

We identified a negative relationship between maternal UtAs levels during pregnancy, fetal development, and neonatal birth outcomes. These findings should be confirmed in future studies with large sample sizes.

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

BACKGROUND AND PURPOSE

The purpose of this case-cohort study was to examine urinary arsenic levels in relation to incident ischemic stroke in the United States.

METHODS

We performed a case-cohort study nested within the REGARDS (REasons for Geographic and Racial Differences in Stroke) cohort. A subcohort (n=2486) of controls was randomly sampled within region-race-sex strata while all incident ischemic stroke cases from the full REGARDS cohort (n=671) were included. Baseline urinary arsenic was measured by inductively coupled plasma-mass spectrometry. Arsenic species, including urinary inorganic arsenic and its metabolites monomethylarsonic acid and dimethylarsinic acid, were measured in a random subset (n=199). Weighted Cox's proportional hazards models were used to calculate hazard ratios and 95% confidence intervals of ischemic stroke by arsenic and its species.

RESULTS

The average follow-up was 6.7 years. Although incident ischemic stroke showed no association with total arsenic or total inorganic arsenic, for each unit higher level of urinary monomethylarsonic acid on a log-scale, after adjustment for potential confounders, ischemic stroke risk increased ≈2-fold (hazard ratio=1.98; 95% confidence interval: 1.12-3.50). Effect modification by age, race, sex, or geographic region was not evident.

CONCLUSIONS

A metabolite of arsenic was positively associated with incident ischemic stroke in this case-cohort study of the US general population, a low-to-moderate exposure area. Overall, these findings suggest a potential role for arsenic methylation in the pathogenesis of stroke, having important implications for future cerebrovascular research.

Nationwide "Hospital Emergent Capability Accreditation by Level-Stroke" Improves Stroke Treatment in Taiwan

Background and Purpose

Recombinant tissue plasminogen activator (rtPA) is one of the proven therapies that improve the outcome of patients with acute ischemic stroke (AIS). In 2009, the Ministry of Health and Welfare, Executive Yuan, Republic of China, launched the project “Hospital Emergent Capability Accreditation by Level-Stroke (HECAL-Stroke)” to improve AIS treatment in Taiwan. The current study was performed to determine whether the project launched by the government was effective in promoting rtPA therapy among AIS patients.

Methods

All participating hospitals were verified and designated as “heavy duty (HD),” “moderate duty (MoD),” or “medium duty (MeD)” according to the stroke center criteria. Four annual indices (rates of treatment, protocol adherence, in-time treatment, and complications) were recorded from 2009 to 2014 as outcome measures. The data were analyzed using the χ² test for significance.

Results

The number of certified hospitals progressively increased from 74 to 112 during the 6-year period and finally consisted of 33 HD, 9 MoD and 70 MeD hospitals in 2014. The annual intravenous rtPA treatment rate increased significantly from 3.0% in 2009 to 4.5% in 2014. The protocol adherence rates were 95.7% in the HD group, 92.4% in the MoD group and 72.8% in the MeD group. The annual in-time treatment rate significantly improved from 26.0% in 2009 to 60.1% in 2014. The overall symptomatic intracranial hemorrhagic rate after rtPA treatment was 8.6%.

Conclusions

Initiation of the HECAL-Stroke project by the government significantly improved rtPA treatment in Taiwan.

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.

Associations between arsenic in drinking water and the progression of chronic kidney disease: A nationwide study in Taiwan

To evaluate the associations between exposure to arsenic in drinking water and the progression of chronic kidney disease (CKD), we conducted a study in Taiwan. We recruited 8854 participants from a nationwide health screening program from 2000 to 2009 who were at least 20 years old and had two checkups in a 24-month period with at least 12 months apart. We defined CKD as having an estimated glomerular filtration rate (eGFR)<90ml/min/1.73m² or renal dysfunction demonstrated by proteinuria and a rapid progression of CKD as a decline in eGFR>5ml/min/1.73m²/year. Arsenic levels were assessed on the basis of a governmental nationwide survey. Of the 8854 participants, 1341 exhibited rapid progression. Participants who lived in areas with arsenic levels≥50μg/L had a higher risk of rapid progression, with an odds ratio of 1.22 (95% confidence interval: 1.05-1.42, p<0.01) after adjusting for hypertension, diabetes mellitus, proteinuria, and anemia. The results showed that a high arsenic level in drinking water was a risk factor for rapid progression of CKD, independent of most of the documented risk factors. Screening and intervention programs should be implemented in endemic areas of exposure to reduce the risk.

Influences of size-fractionated humic acids on arsenite and arsenate complexation and toxicity to Daphnia magna

The intrinsic physicochemical properties of dissolved organic matter (DOM) may affect the mobility and toxicity of arsenic in aquatic environments. In the present study, the humic acid (HA) was ultra-filtered into five fractions according to molecular weight, and their physicochemical properties were characterized. Complexation of HA fractions with arsenite and arsenate was first determined by differential pulse polarography (DPP). The influences of HA fractions on arsenic toxicity were then examined using Daphnia magna as a model organism. As(V) had a higher affinity with HA than As(III), and their complexation was dependent on the total acidity and fluorescence characteristics of DOM. We demonstrated that the acidity and fluorescence also better explained the As toxicity to daphnids than UV absorbance and hydraulic diameter. Arsenic speciation determined by DPP significantly affected the toxicity of arsenite and arsenate. The results extended the free-ion activity model application to the case of arsenic. The present study clearly indicated that DOM with different molecular weights has distinct physicochemical properties, and could influence the speciation and toxicity of As to different extent.

Peripheral Arterial Disease and Its Association With Arsenic Exposure and Metabolism in the Strong Heart Study

At high levels, inorganic arsenic exposure is linked to peripheral arterial disease (PAD) and cardiovascular disease. To our knowledge, no prior study has evaluated the association between low-to-moderate arsenic exposure and incident PAD by ankle brachial index (ABI). We evaluated this relationship in the Strong Heart Study, a large population-based cohort study of American Indian communities. A total of 2,977 and 2,966 PAD-free participants who were aged 45-74 years in 1989-1991 were reexamined in 1993-1995 and 1997-1999, respectively, for incident PAD defined as either ABI <0.9 or ABI >1.4. A total of 286 and 206 incident PAD cases were identified for ABI <0.9 and ABI >1.4, respectively. The sum of inorganic and methylated urinary arsenic species (∑As) at baseline was used as a biomarker of long-term exposure. Comparing the highest tertile of ∑As with the lowest, the adjusted hazard ratios were 0.57 (95% confidence interval (CI): 0.32, 1.01) for ABI <0.9 and 2.24 (95% CI: 1.01, 4.32) for ABI >1.4. Increased arsenic methylation (as percent dimethylarsinate) was associated with a 2-fold increased risk of ABI >1.4 (hazard ratio = 2.04, 95% CI: 1.02, 3.41). Long-term low-to-moderate ∑As and increased arsenic methylation were associated with ABI >1.4 but not with ABI <0.9. Further studies are needed to clarify whether diabetes and enhanced arsenic metabolism increase susceptibility to the vasculotoxic effects of arsenic exposure.

Arsenic trioxide suppresses liver X receptor β and enhances cholesteryl ester transfer protein expression without affecting the liver X receptor α in HepG2 cells

Chronic arsenic exposure is associated with cerebrovascular disease and the formation of atherosclerotic lesions. Our previous study demonstrated that arsenic trioxide (ATO) exposure was associated with atherosclerotic lesion formation through alterations in lipid metabolism in the reverse cholesterol transport process. In mouse livers, the expression of the liver X receptor β (LXR-β) and the cholesteryl ester transfer protein (CETP) was suppressed without any changes to the lipid profile. The aim of this study was to elucidate whether ATO contributes to atherosclerotic lesions by suppressing LXR-β and CETP levels in hepatocytes. HepG2 cells, human hepatocytes, were exposed to different ATO concentrations in vitro. Cell viability was determined by a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide assay. The liver X receptor α (LXR-α), LXR-β, sterol regulatory element-binding protein-1c (SREBP-1c) and CETP protein levels were measured by Western blotting, and their mRNA levels were measured by real-time PCR. Cholesterol efflux was analyzed by flow cytometry. The results showed ATO inhibited LXR-β mRNA and protein levels with a subsequent decrease in SREBP-1c protein levels and reduced cholesterol efflux from HepG2 cells into the extracellular space without influencing LXR-α mRNA and protein levels. CETP protein levels of HepG2 cells were significantly elevated under arsenic exposure. Transfection of LXR-β shRNA did not change CETP protein levels, implying that there is no cross-talk between LXR-β and CETP. In conclusion, arsenic not only inhibits LXR-β and SREBP-1c mRNA and protein levels but also independently increases CETP protein levels in HepG2 cells.

Trace metal contamination in commercial fish and crustaceans collected from coastal area of Bangladesh and health risk assessment

Trace metals contamination in commercial fish and crustaceans have become a great problem in Bangladesh. This study was conducted to determine seven trace metals concentration (Cr, Ni, Cu, Zn, As, Cd, and Pb) in some commercial fishes and crustaceans collected from coastal areas of Bangladesh. Trace metals in fish samples were in the range of Cr (0.15 - 2.2), Ni (0.1 - 0.56), Cu (1.3 - 1.4), Zn (31 - 138), As (0.76 - 13), Cd (0.033 - 0.075), and Pb (0.07 - 0.63 mg/kg wet weight (ww)), respectively. Arsenic (13 mg/kg ww) and Zn (138 mg/kg ww) concentrations were remarkably high in fish of Cox's Bazar due to the interference of uncontrolled huge hatcheries and industrial activities. The elevated concentrations of Cu (400), Zn (1480), and As (53 mg/kg ww) were also observed in crabs of Cox's Bazar which was considered as an absolutely discrepant aquatic species with totally different bioaccumulation pattern. Some metals in fish and crustaceans exceeded the international quality guidelines. Estimated daily intake (EDI) and target cancer risk (TR) revealed high dietary intake of As and Pb, which was obviously a matter of severe public health issue of Bangladeshi coastal people which should not be ignored and concentrate our views to solve this problem with an integrated approaches. Thus, continuous monitoring of these toxic trace elements in seafood and immediate control measure is recommended.

The Association Between Peptic Ulcer Disease and Ischemic Stroke: A Population-Based Longitudinal Study

Stroke is a common cause of death worldwide, but about 30% of ischemic stroke (IS) patients have no identifiable contributing risk factors. Because peptic ulcer disease (PUD) and vascular events share some common risk factors, we conducted a population-based study to evaluate the association between PUD and IS.We followed up a representative sample of 1 million residents of Taiwan using the National Health Insurance Research Database from 1997 to 2011. We defined patients who received medications for PUD and had related diagnosis codes as the PUD group, and a reference group matched by age and sex was sampled from those who did not have PUD. We also collected data on medical history and monthly income. The events of IS occurred after enrollment were compared between the 2 groups. The data were analyzed using Cox proportional hazard models at the 2-tailed significant level of 0.05.The PUD group had higher income and prevalence of hypertension, diabetes mellitus (DM), heart disease, and hyperlipidemia. They also had a higher risk of developing IS with an adjusted hazard ratio of 1.31 (95% confidence interval: 1.20-1.41). Other independent risk factors included male sex, older age, lower income, and co-morbidity of hypertension, diabetes mellitus (DM), and heart disease.PUD is a risk factor for IS, independent of conventional risk factors such as male sex, older age, lower income, and co-morbidity of hypertension, DM, and heart disease. Prevention strategies taking into account PUD should be developed and evaluated.

Prolonged central sensory conduction time in patients with chronic arsenic exposure

BACKGROUND

Many patients from Toroku, Japan, who have chronic arsenic exposure demonstrate whole-body sensory disturbance that is slightly more pronounced in the extremities. Although previous research in this population showed a mild peripheral neuropathy, it is unknown whether these patients have central nervous system impairment. To investigate the lesion sites underlying sensory disturbance related to chronic arsenic poisoning, we analyzed somatosensory evoked potentials (SEP).

METHODS

Clinical features, nerve conduction study results, and median and/or tibial SEP were analyzed in patients with chronic arsenic exposure (total, 13 patients; median & tibial, 4; median, 5; tibial, 4) retrospectively. The SEP findings in patients were compared with those in normal controls.

RESULTS

The median SEP results indicated a conduction delay between the proximal brachial plexus and the primary sensory cortex, and tibial SEP findings indicated a delay between the dorsal gray matter of the lumbosacral cord and the primary sensory cortex.

CONCLUSION

This is the first study to identify an impairment of the central somatosensory pathway in patients with chronic arsenic exposure. Sensory disturbance in these patients is related not only to peripheral neuropathy but also to impairment of the central nervous system.

Levels of arsenic pollution in daily foodstuffs and soils and its associated human health risk in a town in Jiangsu Province, China

The development of industries in rural areas can aggravate the arsenic (As) contamination of the local environment, which may pose unacceptable health risks to the local residents. This paper estimated the health risk posed by inorganic As (iAs) to residents via ingestion of soil, skin contact with soil and consumption of foodstuffs in a typical rural- industrial developed town in southern Jiangsu, China. The average concentrations of total As in soil, rice, fish, shrimp and crab, pork and eggs, vegetables and fruits were detected to be 10.367, 0.104 mg/kg dw (dry weight), 0.050, 0.415, 0.011, 0.013 and 0.017 mg/kg fw (fresh weight), respectively. All of these values are below the maximum allowable concentration in food and soil in China. The deterministic estimation results showed that the hazard quotient (HQ) and excess lifetime cancer risk (R) were 1.28 (0.78-2.31) and 2.38 × 10(-4) (2.71 × 10(-5)-5.09 × 10(-4)) for all age groups, respectively. Males in the age range of 2-29 years and females in the age range of 2-13 years and 18-29 years exhibited non-carcinogenic risk (HQ>1). Carcinogenic risk exceeded the acceptable level of 1 × 10(-)(5) for both genders at all ages. Furthermore, this risk rose with age. The probabilistic estimation results showed that about 28% of residents had non-carcinogenic risk due to over ingestion of iAs. The R value of 90% of residents was greater than 10(-)(5). The sensitivity analysis indicated that the cancer slope factor (SF), the ingestion rates of rice and the iAs concentration in rice were the most relevant variables affecting the assessment outcome. Based on these results, it is recommended that residents reduce their consumption of rice, though it should be noted that the assessment outcome has uncertainty due to estimating iAs from foodstuffs and not considering the bioaccessibility of iAs in foodstuffs. Nevertheless, measures like reducing industrial As emissions, forbidding the use of pesticides, fertilizers and sludge which contain As and optimizing water management in rice paddy fields should be taken to mitigate the risks.

Assessing arsenic intake from groundwater and rice by residents in Prey Veng province, Cambodia

We investigated total daily intake of As by residents in Prey Veng province in the Mekong River basin of Cambodia. Groundwater (n = 11), rice (n = 11) and fingernail (n = 23) samples were randomly collected from the households and analyzed for total As by inductively coupled plasma mass spectrometry. Calculation indicated that daily dose of inorganic As was greater than the lower limits on the benchmark dose for a 0.5% increased incidence of lung cancer (BMDL0.5 equals to 3.0 μg d(-1) kg(-1)body wt.). Moreover, positive correlation between As in fingernail and daily dose of As from groundwater and rice and total daily dose of As were found. These results suggest that the Prey Veng residents are exposed to As in groundwater. As in rice is an additional source which is attributable to high As accumulation in human bodies in the Mekong River basin of Cambodia.

Association between exposure to low to moderate arsenic levels and incident cardiovascular disease. A prospective cohort study

BACKGROUND

Long-term exposure to high levels of arsenic is associated with increased risk for cardiovascular disease, whereas risk from long-term exposure to low to moderate arsenic levels (< 100μg/L in drinking water) is unclear.

OBJECTIVE

To evaluate the association between long-term exposure to low to moderate arsenic levels and incident cardiovascular disease.

DESIGN

Prospective cohort study.

SETTING

The Strong Heart Study baseline visit between 1989 and 1991, with follow-up through 2008.

PATIENTS

3575 American Indian men and women aged 45 to 74 years living in Arizona, Oklahoma, and North and South Dakota.

MEASUREMENTS

The sum of inorganic and methylated arsenic species in urine at baseline was used as a biomarker of long-term arsenic exposure. Outcomes were incident fatal and nonfatal cardiovascular disease.

RESULTS

A total of 1184 participants developed fatal and nonfatal cardiovascular disease. When the highest and lowest quartiles of arsenic concentrations (> 15.7 vs. < 5.8 μg/g creatinine) were compared,the hazard ratios for cardiovascular disease, coronary heart disease, and stroke mortality after adjustment for sociodemographic factors, smoking, body mass index, and lipid levels were 1.65 (95%CI, 1.20 to 2.27; P for trend < 0.001), 1.71 (CI, 1.19 to 2.44; P for trend < 0.001), and 3.03 (CI, 1.08 to 8.50; P for trend = 0.061),respectively. The corresponding hazard ratios for incident cardiovascular disease, coronary heart disease, and stroke were 1.32 (CI,1.09 to 1.59; P for trend = 0.002), 1.30 (CI, 1.04 to 1.62; P for trend = 0.006), and 1.47 (CI, 0.97 to 2.21; P for trend = 0.032).These associations varied by study region and were attenuated after further adjustment for diabetes, hypertension, and kidney disease measures.

LIMITATION

Direct measurement of individual arsenic levels in drinking water was unavailable.

CONCLUSION

Long-term exposure to low to moderate arsenic levels was associated with cardiovascular disease incidence and mortality.

Mobilization of arsenic and other naturally occurring contaminants in groundwater of the Main Ethiopian Rift aquifers

This study investigates the mechanisms of arsenic (As) and other naturally occurring contaminants (F(-), U, V, B, and Mo) mobilization from Quaternary sedimentary aquifers of the Main Ethiopian Rift (MER) and their enrichment in the local groundwater. The study is based on systematic measurements of major and trace elements as well as stable oxygen and hydrogen isotopes in groundwater, coupled with geochemical and mineralogical analyses of the aquifer rocks. The Rift Valley aquifer is composed of rhyolitic volcanics and Quaternary lacustrine sediments. X-ray fluorescence (XRF) results revealed that MER rhyolites (ash, tuff, pumice and ignimbrite) and sediments contain on average 72 wt. % and 65 wt. % SiO2, respectively. Petrographic studies of the rhyolites indicate predominance of volcanic glass, sanidine, pyroxene, Fe-oxides and plagioclase. The As content in the lacustrine sediments (mean = 6.6 mg/kg) was higher than that of the rhyolites (mean: 2.5 mg/kg). The lacustrine aquifers of the Ziway-Shala basin in the northern part of MER were identified as high As risk zones, where mean As concentration in groundwater was 22.4 ± 33.5 (range of 0.60-190 μg/L) and 54% of samples had As above the WHO drinking water guideline value of 10 μg/L. Field As speciation measurements showed that most of the groundwater samples contain predominantly (~80%) arsenate-As(V) over arsenite-As(III) species. The As speciation together with field data of redox potential (mean Eh = +73 ± 65 mV) and dissolved-O2 (6.6 ± 2.2 mg/L) suggest that the aquifer is predominantly oxidative. Water-rock interactions, including the dissolution of volcanic glass produces groundwater with near-neutral to alkaline pH (range 6.9-8.9), predominance of Na-HCO3 ions, and high concentration of SiO2 (mean: 85.8 ± 11.3 mg/L). The groundwater data show high positive correlation of As with Na, HCO3, U, B, V, and Mo (R(2) > 0.5; p < 0.001). Chemical modeling of the groundwater indicates that Fe-oxides and oxyhydroxides minerals were saturated in the groundwater, suggesting that the As reactivity is controlled by adsorption/desorption processes with these minerals. The data show that As and other oxyanion-forming elements such as U, B, Mo, and V had typically higher concentrations at pH > ~8, reflecting the pH-dependence of their mobilization. Based on the geochemical and stable isotope variations we have established a conceptual model for the occurrence of naturally occurring contaminants in MER groundwater: 1) regional groundwater recharge from the Highland, along the Rift margins, followed by lateral flow and water-rock interactions with the aquifer rocks resulted in a gradual increase of the salinity and naturally occurring contaminants towards the center of the valley; and (2) local δ(18)O-rich lake water recharge into adjacent shallow aquifers, followed by additional mobilization of As and other oxyanion-forming elements from the aquifer rocks. We posit that the combined physical-chemical conditions of the aquifers such as oxidizing state, Na-HCO3 composition, and pH>~8 lead to enhanced mobilization of oxyanion-forming elements from Fe-oxides and consequently contamination of local groundwater. These geochemical conditions characterize groundwater resources along the Eastern African Rift and thus constitute a potential threat to the quality of groundwater in larger areas of Eastern Africa.

Health risk from As contaminated fish consumption by population living around River Chenab, Pakistan

We analyzed six edible fish species (Securicola gora; Cirrhinus reba; Rita rita; Sperata sarvari; Culpisoma naziri and Labeo kalbasu) to evaluation As contamination. These species were caught from the River Chenab of Pakistan. The aim of this study was to determine the concentration of arsenic (As) and the antioxidant response in the muscle, liver and gills. The sampling sites were divided into agricultural, industrial and urban land uses. Although, the highest concentration of As, and the antioxidant activity was found in the liver, but the muscles also had a high concentration of As than that of gills. The range of As detected in these tissues was in the following order: Liver (0.009-3.95μgg(-1))>muscles (0.006-3.5μgg(-1))>gills (0.002-2.96μgg(-1)). Furthermore, the R. rita showed the highest concentration of As (2.18μgg(-1)) followed by S. sarvari (1.98μgg(-1)). The median concentrations of As, in the liver and muscles were also above the FAO/WHO, EPA permissible limits. The LPO activity was significantly related to As, which showed a possibility of cell membrane damage in these species. The human health risk assessment revealed that higher than normal concentration of As in muscle was particularly hazardous for the younger population.

Arsenic exposure and cardiovascular disease: an updated systematic review

In epidemiologic studies, high-chronic arsenic exposure has been associated with cardiovascular disease, despite methodological limitations. At low-moderate arsenic levels, the evidence was inconclusive. Here, we update a previous systematic review (Am J Epidemiol 2005;162:1037-49) examining the association between arsenic exposure and cardiovascular disease. Eighteen studies published since 2005 were combined with 13 studies from the previous review. We calculated pooled relative risks by comparing the highest versus the lowest exposure category across studies. For high exposure (arsenic in drinking water > 50 μg/L), the pooled relative risks (95 % confidence interval) for cardiovascular disease, coronary heart disease, stroke, and peripheral arterial disease were 1.32 (95 % CI:1.05-1.67), 1.89 (95 % CI:1.33-2.69), 1.08 (95 % CI:0.98-1.19), and 2.17 (95 % CI:1.47-3.20), respectively. At low-moderate arsenic levels, the evidence was inconclusive. Our review strengthens the evidence for a causal association between high-chronic arsenic exposure and clinical cardiovascular endpoints. Additional high quality studies are needed at low-moderate arsenic levels.

Atherosclerosis induced by arsenic in drinking water in rats through altering lipid metabolism

Arsenic in drinking water is a global environmental health problem, and the exposure may increase cardiovascular and cerebrovascular diseases mortalities, most likely through causing atherosclerosis. However, the mechanism of atherosclerosis formation after arsenic exposure is still unclear. To study the mechanism of atherosclerosis formation after arsenic exposure and explore the role of high cholesterol diet (HCD) in this process, we fed spontaneous hypertensive rats and Wistar Kyoto rats with basal diet or HCD and provided with them drinking water containing arsenic at different ages and orders for 20 consecutive weeks. We measured high density lipoprotein cholesterol (HDL-C), low density lipoprotein cholesterol (LDL-C), total cholesterol, triglycerides, heat shock protein 70 (HSP 70), and high sensitive C-reactive protein (hs-CRP) at predetermined intervals and determined expressions of cholesteryl ester transfer protein-1 (CETP-1) and liver X receptor β (LXRβ) in the liver. Atherosclerosis was determined by examining the aorta with hematoxylin and eosin stain. After 20 weeks, we found arsenic, alone or combined with HCD, may promote atherosclerosis formation with transient increases in HSP 70 and hs-CRP. Early combination exposure decreased the HDL-C/LDL-C ratio without changing the levels of total cholesterol and triglyceride until 30 weeks old. Both CETP-1 and LXRβ activities were suppressed, most significantly in early combination exposure. In conclusion, arsenic exposure may induce atherosclerosis through modifying reverse cholesterol transport in cholesterol metabolism and suppressing LXRβ and CEPT-1 expressions. For decreasing atherosclerosis related mortality associated with arsenic, preventing exposure from environmental sources in early life is an important element.

Aberrantly Expressed Genes in HaCaT Keratinocytes Chronically Exposed to Arsenic Trioxide

Inorganic arsenic is a known environmental toxicant and carcinogen of global public health concern. Arsenic is genotoxic and cytotoxic to human keratinocytes. However, the biological pathways perturbed in keratinocytes by low chronic dose inorganic arsenic are not completely understood. The objective of the investigation was to discover the mechanism of arsenic carcinogenicity in human epidermal keratinocytes. We hypothesize that a combined strategy of DNA microarray, qRT-PCR and gene function annotation will identify aberrantly expressed genes in HaCaT keratinocyte cell line after chronic treatment with arsenic trioxide. Microarray data analysis identified 14 up-regulated genes and 21 down-regulated genes in response to arsenic trioxide. The expression of 4 up-regulated genes and 1 down-regulated gene were confirmed by qRT-PCR. The up-regulated genes were AKR1C3 (Aldo-Keto Reductase family 1, member C3), IGFL1 (Insulin Growth Factor-Like family member 1), IL1R2 (Interleukin 1 Receptor, type 2), and TNFSF18 (Tumor Necrosis Factor [ligand] SuperFamily, member 18) and down-regulated gene was RGS2 (Regulator of G-protein Signaling 2). The observed over expression of TNFSF18 (167 fold) coupled with moderate expression of IGFL1 (3.1 fold), IL1R2 (5.9 fold) and AKR1C3 (9.2 fold) with a decreased RGS2 (2.0 fold) suggests that chronic arsenic exposure could produce sustained levels of TNF with modulation by an IL-1 analogue resulting in chronic immunologic insult. A concomitant decrease in growth inhibiting gene (RGS2) and increase in AKR1C3 may contribute to chronic inflammation leading to metaplasia, which may eventually lead to carcinogenicity in the skin keratinocytes. Also, increased expression of IGFL1 may trigger cancer development and progression in HaCaT keratinocytes.