Low-dose arsenic: in search of a risk threshold

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.

Impact of lowering the US maximum contaminant level on arsenic exposure: Differences by race, region, and water arsenic in NHANES 2003-2014

Our objective was to evaluate regional and sociodemographic inequalities in water arsenic exposure reductions associated with the US Environmental Protection Agency's Final Arsenic Rule, which lowered the arsenic maximum contaminant level to 10 μg/L in public water systems. We analyzed 8544 participants from the 2003-14 National Health and Nutrition Examination Survey (NHANES) reliant on community water systems (CWSs). We estimated arsenic exposure from water by recalibrating urinary dimethylarsinate (rDMA) to remove smoking and dietary contributions. We evaluated mean differences and corresponding percent reductions of urinary rDMA comparing subsequent survey cycles to 2003-04 (baseline), stratified by region, race/ethnicity, educational attainment, and tertile of CWS arsenic assigned at the county level. The overall difference (percent reduction) in urine rDMA was 0.32 μg/L (9%) among participants with the highest tertile of CWS arsenic, comparing 2013-14 to 2003-04. Declines in urinary rDMA were largest in regions with the highest water arsenic: the South [0.57 μg/L (16%)] and West [0.46 μg/L, (14%)]. Declines in urinary rDMA levels were significant and largest among Mexican American [0.99 μg/L (26%)] and Non-Hispanic White [0.25 μg/L (10%)] participants. Reductions in rDMA following the Final Arsenic Rule were highest among participants with the highest CWS arsenic concentrations, supporting legislation can benefit those who need it the most, although additional efforts are still needed to address remaining inequalities in CWS arsenic exposure.

Behavioral determinants of arsenic-safe water use among Great Plains Indian Nation private well users: results from the Community-Led Strong Heart Water Study Arsenic Mitigation Program

BACKGROUND

The objective of this study was to evaluate the behavioral determinants associated with exclusive use of arsenic-safe water in the community-led Strong Heart Water Study (SHWS) arsenic mitigation program.

METHODS

The SHWS is a randomized controlled trial of a community-led arsenic mitigation program designed to reduce arsenic exposure among private well users in American Indian Great Plains communities. All households received point-of-use (POU) arsenic filters installed at baseline and were followed for 2 years. Behavioral determinants selected were those targeted during the development of the SHWS program, and were assessed at baseline and follow-up.

RESULTS

Among participants, exclusive use of arsenic-safe water for drinking and cooking at follow-up was associated with higher self-efficacy for accessing local resources to learn about arsenic (OR: 5.19, 95% CI: 1.48-18.21) and higher self-efficacy to resolve challenges related to arsenic in water using local resources (OR: 3.11, 95% CI: 1.11-8.71). Higher commitment to use the POU arsenic filter faucet at baseline was also a significant predictor of exclusive arsenic-safe water use for drinking (OR: 32.57, 95% CI: 1.42-746.70) and cooking (OR: 15.90, 95% CI: 1.33-189.52) at follow-up. From baseline to follow-up, the SHWS program significantly increased perceived vulnerability to arsenic exposure, self-efficacy, descriptive norms, and injunctive norms. Changing one's arsenic filter cartridge after installation was associated with higher self-efficacy to obtain arsenic-safe water for drinking (OR: 6.22, 95% CI: 1.33-29.07) and cooking (OR: 10.65, 95% CI: 2.48-45.68) and higher perceived vulnerability of personal health effects (OR: 7.79, 95% CI: 1.17-51.98) from drinking arsenic-unsafe water.

CONCLUSIONS

The community-led SHWS program conducted a theory-driven approach for intervention development and evaluation that allowed for behavioral determinants to be identified that were associated with the use of arsenic safe water and changing one's arsenic filter cartridge. These results demonstrate that theory-driven, context-specific formative research can influence behavior change interventions to reduce water arsenic exposure. The SHWS can serve as a model for the design of theory-driven intervention approaches that engage communities to reduce arsenic exposure.

TRIAL REGISTRATION

The SHWS is registered with ClinicalTrials.gov (Identifier: NCT03725592).

Source-oriented risk and lung-deposited surface area (LDSA) of ultrafine particles in a Southeast Asia urban area

Submicron and ultrafine particle (UFP) exposure may be epidemiologically and toxicologically linked to pulmonary, neurodegenerative, and cardiovascular diseases. This study explores UFP and fine particle sources using a positive matrix factorization (PMF) model based on PM_2.5 chemical compositions and particle number size distributions (PNSDs). The particle chemical composition and size distribution contributions are simultaneously identified to evaluate lung deposition and excess cancer risks. High correlations between the PNSD and chemical composition apportionment results were observed. Fresh and aged traffic particles dominated the number concentrations, while heterogeneous, photochemical reactions and/or regional transport may have resulted in secondary aerosol formation. Fresh and aged road traffic particle sources mostly contributed to the lung deposition dosage in the pulmonary region (~53 %), followed by the tracheobronchial (~30.4 %) and head regions (~16.6 %). However, lung-deposited surface area (LDSA) concentrations were dominated by aged road traffic (~39.2 %) and secondary aerosol (~33.2 %) sources. The excess cancer risks caused by Cr⁶⁺, Ni, and As were also mainly contributed to by aged road traffic (~31.7 %) and secondary aerosols (~67 %). The source apportionments based on the physical and chemical properties of aerosol particles are complementary, offering a health impact benchmark of UFPs in a Southeast Asia urban city.

Biomonitoring California Protocol for Following up on Elevated Levels of Urinary Arsenic

OBJECTIVES

to develop and implement a follow-up protocol for Biomonitoring California study participants with elevated levels of urinary arsenic, particularly inorganic forms.

METHODS

We selected 20 μg/L as the level of concern for urinary inorganic arsenic; samples with total arsenic ≥20 μg/L were speciated. Participants with elevated inorganic arsenic were notified of their level and invited to participate in a telephone survey to help determine possible exposure sources. We illustrate the protocol in four Biomonitoring California studies, which collected samples from 2010-2013 in locations across the state.

RESULTS

48 participants in the four studies had elevated urinary inorganic arsenic levels. Consumption of rice and rice-based products was the most commonly identified potential source of inorganic arsenic exposure.

CONCLUSIONS

Of 48 participants with elevated inorganic arsenic, 27 would have been missed if we had used the previously published threshold of 50 µg/L total arsenic to identify urine samples for speciation. This protocol fills a gap in the clinical literature by providing a more health-protective approach to identify individuals with elevated urinary inorganic arsenic and help determine potentially significant exposure sources.

Evaluation of a water arsenic filter in a participatory intervention to reduce arsenic exposure in American Indian communities: The Strong Heart Water Study

Many rural populations, including American Indian communities, that use private wells from groundwater for their source of drinking and cooking water are disproportionately exposed to elevated levels of arsenic. However, programs aimed at reducing arsenic in American Indian communities are limited. The Strong Heart Water Study (SHWS) is a randomized controlled trial aimed at reducing arsenic exposure among private well users in American Indian Northern Great Plains communities. The community-led SHWS program installed point-of-use (POU) arsenic filters in the kitchen sink of households, and health promoters delivered arsenic health communication programs. In this study we evaluated the efficacy of these POU arsenic filters in removing arsenic during the two-year installation period. Participants were randomized into two arms. In the first arm households received a POU arsenic filter, and 3 calls promoting filter use (SHWS mobile health (mHealth) & filter arm). The second arm received the same filter and phone calls, and 3 in-person home visits and 3 Facebook messages (SHWS intensive arm) for program delivery. Temporal variability in water arsenic concentrations from the main kitchen faucet was also evaluated. A total of 283 water samples were collected from 50 households with private wells from groundwater (139 filter and 144 kitchen faucet samples). Ninety-three percent of households followed after baseline had filter faucet water arsenic concentrations below the arsenic maximum contaminant level of 10 μg/L at the final visit during our 2 year study period with no difference between study arms (98 % in the intensive arm vs. 94 % in the mHealth & filter arm). No significant temporal variation in kitchen arsenic concentration was observed over the study period (intraclass correlation coefficient = 0.99). This study demonstrates that POU arsenic filters installed for the community participatory SHWS program were effective in reducing water arsenic concentration in study households in both arms, even with delivery of the POU arsenic filter and mHealth program only. Furthermore, we observed limited temporal variability of water arsenic concentrations from kitchen faucet samples collected over time from private wells in our study setting.

Long-term exposure to low-level arsenic in drinking water is associated with cause-specific mortality and hospitalization in the Mt. Amiata area (Tuscany, Italy)

BACKGROUND

Arsenic in drinking water is a global public health concern. This study aims to investigate the association between chronic low-level exposure to arsenic in drinking water and health outcomes in the volcanic area of Mt. Amiata in Italy, using a residential cohort study design.

METHODS

Chronic exposure to arsenic in drinking water was evaluated using monitoring data collected by the water supplier. A time-weighted average arsenic exposure was estimated for the period 2005-2010. The population-based cohort included people living in five municipalities in the Mt. Amiata area between 01/01/1998 and 31/12/2019. Residence addresses were georeferenced and each subject was matched with arsenic exposure and socio-economic status. Mortality and hospital discharge data were selected from administrative health databases. Cox proportional hazard models were used to test the associations between arsenic exposure and outcomes, with age as the temporal axis and adjusting for gender, socio-economic status and calendar period.

RESULTS

The residential cohort was composed of 30,910 subjects for a total of 407,213 person-years. Analyses reported risk increases associated with exposure to arsenic concentrations in drinking water > 10 µg/l for non-accidental mortality (HR = 1.07 95%CI:1.01-1.13) and malignant neoplasms in women (HR = 1.14 95%CI:0.97-1.35). Long-term exposure to arsenic concentrations > 10 µg/l resulted positively associated with several hospitalization outcomes: non-accidental causes (HR = 1.06 95%CI:1.03-1.09), malignant neoplasms (HR = 1.10 95%CI:1.02-1.19), lung cancer (HR = 1.85 95%CI:1.14-3.02) and breast cancer (HR = 1.23 95%CI:0.99-1.51), endocrine disorders (HR = 1.13 95%CI:1.02-1.26), cardiovascular (HR = 1.12 95%CI:1.06-1.18) and respiratory diseases (HR = 1.10 95%CI:1.03-1.18). Some risk excesses were also observed for an exposure to arsenic levels below the regulatory standard, with evidence of exposure-related trends.

CONCLUSIONS

Our population-based cohort study in the volcanic area of Mt. Amiata showed that chronic exposure to arsenic concentrations in drinking water above the current regulatory limit was associated with a plurality of outcomes, in terms of both mortality and hospitalization. Moreover, some signs of associations emerge even at very low levels of exposure, ​​below the current regulatory limit, highlighting the need to monitor arsenic concentrations continuously and implement policies to reduce concentrations in the environment as far as possible.

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.

Overview of the cardiovascular effects of environmental metals: New preclinical and clinical insights

Environmental causes of cardiovascular diseases (CVDs) are global health issues. In particular, an association between metal exposure and CVDs has become evident but causal evidence still lacks. Therefore, this symposium at the Society of Toxicology 2022 annual meeting addressed epidemiological, clinical, pre-clinical animal model-derived and mechanism-based evidence by five presentations: 1) An epidemiologic study on potential CVD risks of individuals exposed occupationally and environmentally to heavy metals; 2) Both presentations of the second and third were clinical studies focusing on the potential link between heavy metals and pulmonary arterial hypertension (PAH), by presenting altered blood metal concentrations of both non-essential and essential metals in the patients with PAH and potential therapeutic approaches; 3) Arsenic-induced atherosclerosis via inflammatory cells in mouse model; 4) Pathogenic effects on the heart by adult chronic exposure to very low-dose cadmium via epigenetic mechanisms and whole life exposure to low dose cadmium via exacerbating high-fat-diet-lipotoxicity. This symposium has brought epidemiologists, therapeutic industry, physicians, and translational scientists together to discuss the health risks of occupational and environmental exposure to heavy metals through direct cardiotoxicity and indirect disruption of homeostatic mechanisms regulating essential metals, as well as lipid levels. The data summarized by the presenters infers a potential causal link between multiple metals and CVDs and defines differences and commonalities. Therefore, summary of these presentations may accelerate the development of efficient preventive and therapeutic strategies by facilitating collaborations among multidisciplinary investigators.

Natural and Anthropogenic Processes Affecting Domestic Groundwater Quality within the Northwestern Appalachian Basin

Domestic wells serve as the primary drinking-water source for rural residents in the northern Appalachian Basin (NAB), despite a limited understanding of contaminant distributions in groundwater sources. We employ a newly collected dataset of 216 water samples from domestic wells in Ohio and West Virginia and an integrated contaminant-source attribution method to describe water quality in the western NAB and characterize key agents influencing contaminant distributions. Our results reveal arsenic and nitrate concentrations above federal maximum contaminant levels (MCLs) in 6.8 and 1.3% of samples and manganese concentrations above health advisory in 7.3% of samples. Recently recharged groundwaters beneath upland regions appear vulnerable to surface-related impacts, including nitrate pollution from agricultural activities and salinization from road salting and domestic sewage sources. Valley regions serve as terminal discharge points for long-residence-time groundwaters, where mixing with basin brines is possible. Arsenic impairments occurred in alkaline groundwaters with major-ion compositions altered by ion exchange and in low-oxygen metal-rich groundwaters. Mixing with as much as 4-10% of mine discharge-like waters was observed near coal mining operations. Our study provides new insights into key agents of groundwater impairment in an understudied region of the NAB and presents an integrated approach for contaminant-source attribution applicable to other regions of intensive resource extraction.

Biogeochemical behaviour of geogenic As in a confined aquifer of the Sologne region, France

Arsenic (As) is one of the main toxic elements of geogenic origin that impact groundwater quality and human health worldwide. In some groundwater wells of the Sologne region (Val de Loire, France), drilled in a confined aquifer, As concentrations exceed the European drinking water standard (10 μg L^-1). The monitoring of one of these drinking water wells showed As concentrations in the range 20-25 μg L^-1. The presence of dissolved iron (Fe), low oxygen concentration and traces of ammonium indicated reducing conditions. The δ³⁴S_SO4 was anticorrelated with sulphate concentration. Drilling allowed to collect detrital material corresponding to a Miocene floodplain and crevasse splay with preserved plant debris. The level that contained the highest total As concentration was a silty-sandy clay containing 26.9 mg kg^-1 As. The influence of alternating redox conditions on the behaviour of As was studied by incubating this material with site groundwater, in biotic or inhibited bacterial activities conditions, without synthetic organic nutrient supply, in presence of H₂ during the reducing periods. The development of both AsV-reducing and AsIII-oxidising microorganisms in biotic conditions was evidenced. At the end of the reducing periods, total As concentration strongly increased in biotic conditions. The microflora influenced As speciation, released Fe and consumed nitrate and sulphate in the water phase. Microbial communities observed in groundwater samples strongly differed from those obtained at the end of the incubation experiment, this result being potentially related to influence of the sediment compartment and to different physico-chemical conditions. However, both included major Operating Taxonomic Units (OTU) potentially involved in Fe and S biogeocycles. Methanogens emerged in the incubated sediment presenting the highest solubilised As and Fe. Results support the hypothesis of in-situ As mobilisation and speciation mediated by active biogeochemical processes.

Maternal Folate Status and the Relation between Gestational Arsenic Exposure and Child Health Outcomes

Gestational arsenic exposure adversely impacts child health. Folate-mediated 1-carbon metabolism facilitates urinary excretion of arsenic and may prevent arsenic-related adverse health outcomes. We investigated the potential for maternal folate status to modify associations between gestational arsenic exposure and child health. We used data from 364 mother-child pairs in the MIREC study, a prospective pan-Canadian cohort. During pregnancy, we measured first trimester urinary arsenic concentrations, plasma folate biomarkers, and folic acid supplementation intake. At age 3 years, we evaluated twelve neurodevelopmental and anthropometric features. Using latent profile analysis and multinomial regression, we developed phenotypic profiles of child health, estimated covariate-adjusted associations between arsenic and these phenotypic profiles, and evaluated whether folate status modified these associations. We identified three phenotypic profiles of neurodevelopment and three of anthropometry, ranging from less to more optimal child health. Gestational arsenic was associated with decreased odds of optimal neurodevelopment. Maternal folate status did not modify associations of arsenic with neurodevelopmental phenotypic profiles, but gestational arsenic was associated with increased odds of excess adiposity among those who exceed recommendations for folic acid (>1000 μg/day). However, arsenic exposure was low and folate status was high. Gestational arsenic exposure may adversely impact child neurodevelopment and anthropometry, and maternal folate status may not modify these associations; however, future work should examine these associations in more arsenic-exposed or lower folate-status populations.

Elevated serum periostin levels among arsenic-exposed individuals and their associations with the features of asthma

Chronic exposure to arsenic via drinking water is a serious public health issue in many countries. Arsenic causes not only cancers but also non-malignant diseases, including asthma. We have previously reported that arsenic exposure increases the risk of Th2-mediated allergic asthma. The serum level of periostin, an extracellular matrix protein activated by Th2 cytokines, is recognized as a biomarker for Th2-mediated eosinophilic asthma and contributes to enhanced airway inflammation and remodeling. However, the role of periostin in arsenic-related asthma is unknown. Therefore, this study was designed to explore the associations of serum periostin levels with arsenic exposure and the features of asthma in 442 individuals in Bangladesh who participated in our previous study. Exposure levels of the participants were determined by measuring the arsenic concentrations in drinking water, hair, and nails through inductively coupled plasma mass spectroscopy. Periostin levels in serum were assessed by immunoassay. In this study, we found that serum periostin levels of the participants were increased with increasing exposure to arsenic. Notably, even the participants with 10.1-50 μg/L arsenic in drinking water had significantly higher levels of periostin than participants with <10 μg/L of water arsenic. Elevated serum periostin levels were positively associated with serum levels of Th2 mediators, such as interleukin (IL)-4, IL-5, IL-13, and eotaxin. Each log increase in periostin levels was associated with approximately eight- and three-fold increases in the odds ratios (ORs) for reversible airway obstruction (RAO) and asthma symptoms, respectively. Additionally, causal mediation analyses revealed that arsenic exposure metrics had both direct and indirect (periostin-mediated) effects on the risk of RAO and asthma symptoms. Thus, the results suggested that periostin may be involved in the arsenic-related pathogenesis of Th2-mediated asthma. The elevated serum periostin levels may predict the greater risk of asthma among the people living in arsenic-endemic areas.

Subcellular metal partitioning as a novel tool in ecotoxicological elasmobranch assessments: The case of lesser numbfish (Narcine brasiliensis) affected by the Mariana dam disaster in Southeastern Brazil

This study comprises a novel report on subcellular metal partitioning and metallothionein (MT) metal detoxification efforts in lesser numbfish (Narcine brasiliensis) electric ray specimens, as well as the first assessment on MT contents in any ray electric organ. Individuals sampled from an area in Southeastern Brazil affected by the Mariana dam rupture disaster were assessed concerning subcellular metal partitioning and MT metal-detoxification in the liver, gonads, electric organ and muscle of both adults and embryos. Yolk was also assessed when available. Relative total and heat-stable (bioavailable) metal and metalloid comparisons between adults and embryos in different developmental stages demonstrates maternal transfer of both total and bioavailable metals and significant MT associations demonstrate the detoxification of As, Ag, Mn, Ni, Cd, Co, Cu, Se and V through this biochemical pathway. Our findings expand the lacking ecotoxicological assessments for this near-threatened species and indicates significant ecological concerns, warranting further biomonitoring efforts.

Health damage to housewives by contaminants emitted from coal combustion in the Chinese countryside: focusing on day-to-day cooking

PURPOSE

The study aimed to estimate the health damage and find out the main exposure pathways of housewives posed by polycyclic aromatic hydrocarbons (PAHs) and heavy metals (HMs) from coal combustion in rural areas of China.

METHODS

We obtained the concentrations of 16 PAHs and 8 HMs from published literatures and the Monte Carlo simulation was used to process and analysis the data. Sensitivity analysis was also applied to clear parameter uncertainty and the health damage of housewives was quantitatively evaluated by loss of life expectancy.

RESULTS

Housewives' carcinogenic risks from PAHs exposure were in descending order of inhalation > ingestion > dermal contact, while exposed to HMs were ingestion > dermal contact > inhalation. The carcinogenic risks from PAHs primarily originated from benzo[a]pyrene (BaP), dibenz[ah]anthracene (DahA) and benzo[b]fluorathene (BbF). For HMs, arsenic posed the highest carcinogenic risk to housewives, with a contribution of 92.98%. In addition, the life expectancy loss of housewives exposed to PAHs was 469.04 min from inhalation and 51.82 min for HMs from ingestion.

CONCLUSION

Through a comprehensive assessment of the health risks in housewives exposed to emissions from coal combustion, we can gain insight into the hazards from PAHs and HMs in housewives, and take measures to reduce their exposure risks.

Low‑Level Environmental Heavy Metals are Associated with Obesity Among Postmenopausal Women in a Southern State

Both arsenic and cadmium are reported to be toxic to humans. The use of saliva as a biomarker of low-level exposures to these elements has not been adequately explored, and the putative relationship between exposure and obesity is unclear. This cross-sectional study aims to investigate the relationship between salivary arsenic and cadmium concentrations and their association with obesity. Arsenic and cadmium concentrations were analyzed in human saliva samples by Inductively Coupled Plasma-Mass Spectrometry on 270 randomly selected women who participated in the Arkansas Rural Community Health Study. Multivariable logistic regression was performed to evaluate the association between heavy metal concentrations and obesity. Stratified logistic regression was performed based on menopausal status. Generalized linear models were used to evaluate weight gain velocity. Significant positive associations were observed in postmenopausal women for both arsenic (OR = 4.43, 95% CI 1.91-10.28) and cadmium (OR = 2.72, 95% CI 1.23-5.99) concentrations, as well as significant trends among tertiles (p < 0.01 and p = 0.01, respectively). No relationship with obesity was evident among premenopausal women for either metal. A dose-response relationship was observed between increasing weight gain velocity and increasing metal concentrations. At concentrations well below governmental and industrial standards for acute toxicity, significant associations between obesity and concentration of these heavy metals are evident. The rate at which individuals gain weight is affected by metal concentrations and may play a role in the rapid increase in weight in postmenopausal women. These results might explain, in part, the missing variability in the increasing obesity pandemic in certain population exposed to these environmental toxicants.

T helper 2-driven immune dysfunction in chronic arsenic-exposed individuals and its link to the features of allergic asthma

Limited information is available regarding the effects of arsenic exposure on immune function. We have recently reported that chronic exposure to As was associated asthma, as determined by spirometry and respiratory symptoms. Because T helper 2 (Th2)-driven immune responses are implicated in the pathogenesis of allergic diseases, including asthma, we studied the associations of serum Th1 and Th2 mediators with the As exposure markers and the features of asthma among individuals exposed to As. A total of 553 blood samples were selected from the same study subjects recruited in our previous asthma study. Serum levels of Th1 and Th2 cytokines were analyzed by immunoassay. Subjects' arsenic exposure levels (drinking water, hair and nail arsenic concentrations) were determined by inductively coupled plasma mass spectroscopy. Arsenic exposure levels of the subjects showed significant positive associations with serum Th2-mediators- interleukin (IL)-4, IL-5, IL-13, and eotaxin without any significant changes in Th1 mediators- interferon-γ and tumor necrosis factor-α. The ratios of Th2 to Th1 mediators were significantly increased with increasing exposure to As. Notably, most of the Th2 mediators were positively associated with serum levels of total immunoglobulin E and eotaxin. The serum levels of Th2 mediators were significantly higher in the subjects with asthma than those without asthma. The results of our study suggest that the exacerbated Th2-driven immune responses are involved in the increased susceptibility to allergic asthma among individuals chronically exposed to As.

Winter arsenic pollution in 10 forest ecosystems in the mountainous border regions of the Czech Republic

Arsenic (As) concentrations and deposition fluxes were measured in snow and rime at 10 mountain-top sites near the borders between the Czech Republic and Austria, Germany, Poland, and Slovakia during three consecutive winter seasons (2009-2011). Our study was performed at a time following several decades of sharply decreasing regional atmospheric pollution and following the 2006 implementation of stricter air quality standards across Europe. Our objective was to compare vertical and horizontal depositions of soluble and insoluble As forms throughout the Czech Republic and define a recent Central European As pollution gradient. Arsenic soluble in weak nitric acid contributed 83 to 85% to the total As deposition, with the remaining 17-15% bound to stable particulate forms. The highest As deposition rates were recorded in the eastern Czech Republic near the borders with Poland and Slovakia. Complementary hydrochemical monitoring in four mountain-slope catchments situated near selected main study sites revealed a further decrease in open-area As deposition by the end of 2018 in the east of the country. In contrast, spruce canopy throughfall flux did not change significantly between 2009-2011 and 2016-2018. The site-specific relative roles of coal-burning-derived and ore-smelting-derived atmospheric As are discussed.

Drinking Water Criteria for Arsenic in High-Income, Low-Dose Countries: The Effect of Legislation on Public Health

Due to the potential health risks at very low concentrations, the criterion for arsenic in drinking water has been debated. High-income, low-dose countries are uniquely positioned to follow WHO's recommendation of keeping concentrations "as low as reasonably possible." In this policy analysis, 47646 arsenic analyses from Denmark are used to follow the effect of lowering the national criterion from 50 to 5 μg/L. The first 3 years (2002-2004) following the criterion change, 106 waterworks were identified as noncompliant. An additional 64 waterworks were identified as noncompliant in the next 12 years (2005-2016). Of the 106 waterworks initially (2002-2004) aware of the violation, an average concentration drop from 6 to 3 μg/L was observed during a 6 year period following a lag time of 1 year. After this point, no further improvements were observed. Thirteen years after regulation was imposed, 25 of 170 waterworks were still in violation. The results suggest that legislation alone is insufficient to ensure better drinking water quality at some waterworks and that stakeholders' drivers and barriers to change also play an important role. In an exploration of five legislation scenarios, this study showed that a criterion of 1 μg/L would require action by more than 500 Danish waterworks, with treatment costs from 0.06 to 0.70 €/m³. These scenarios illustrate that it can be technically feasible and affordable to lower the arsenic criterion below 5 μg/L in low-dose, high-income countries. However, more information is needed to apply a cost-benefit model, and comparative studies from other counties are warranted.

Recommended Sampling Intervals for Arsenic in Private Wells

Geogenic arsenic in drinking water is a worldwide problem. For private well owners, testing (e.g., private or government laboratory) is the main method to determine arsenic concentration. However, the temporal variability of arsenic concentrations is not well characterized and it is not clear how often private wells should be tested. To answer this question, three datasets, two new and one publicly available, with temporal arsenic data were utilized: 6370 private wells from New Jersey tested at least twice since 2002, 2174 wells from the USGS NAWQA database, and 391 private wells sampled 14 years apart from Bangladesh. Two arsenic drinking water standards are used for the analysis: 10 µg/L, the WHO guideline and EPA standard or maximum contaminant level (MCL) and 5 µg/L, the New Jersey MCL. A rate of change was determined for each well and these rates were used to predict the temporal change in arsenic for a range of initial arsenic concentrations below an MCL. For each MCL and initial concentration, the probability of exceeding an MCL over time was predicted. Results show that to limit a person to below a 5% chance of drinking water above an MCL, wells that are ½ an MCL and above should be tested every year and wells below ½ an MCL should be tested every 5 years. These results indicate that one test result below an MCL is inadequate to ensure long-term compliance. Future recommendations should account for temporal variability when creating drinking water standards and guidance for private well owners.

The Hormetic Effect of Arsenic Trioxide on Rat Pulpal Cells: An In Vitro Preliminary Study

Objectives  Despite the agreement that there is no longer any indication for arsenic use in modern endodontics, some concerns are surfacing about the minute amount of arsenic trioxide (As ₂ O ₃ ) released from Portland cement-based materials. The present study investigated the effect of different concentrations of As ₂ O ₃ on rat pulpal cells and the efficacy of N -acetylcysteine (NAC) in preventing As ₂ O ₃ -mediated toxicity.

Materials and Methods  Cytotoxicities of 50, 10, or 5 µm As ₂ O ₃ and the effect of cells co-treatment with 50 µm As ₂ O ₃ and 5,000 µm NAC or 500 µm NAC were tested at 24 hours or 3 days. Cell viability was assessed by means of MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay and cellular morphological changes were observed under phase contrast microscope.

Statistical Analysis  Two-way analysis of variance with Tukey’s post-hoc test was used to evaluate differences between the groups (α = 0.05).

Results  At both exposure times, 50 µm As ₂ O ₃ resulted in lower optical density (OD) values when compared with 10 or 5 µm As ₂ O ₃ . At 24 hours, 10 µm As ₂ O ₃ resulted in a higher OD value compared with the control; however, at 3 days the difference was statistically insignificant. At each exposure time, the OD value of 5 µm As ₂ O ₃ group was comparable to the control and 10 µm As ₂ O ₃ group. There were no significant differences between 50 µm As ₂ O ₃ group and 500 μm NAC+50 μm As ₂ O ₃ group; however, these two groups had lower OD values when compared with 5,000 μm NAC+50 μm As ₂ O ₃ group at 24 hours and 3 days. The latter group showed significantly lower OD value in comparison with the control at 24 hours and 3 days. Control cells were polygonal-shaped while 50 µm As ₂ O ₃ -treated cells exhibited contracted and spherical morphology with increased intercellular spaces. At 24 hours, 10 μm and 5 µm As ₂ O ₃ -treated cells were slightly hypertrophic. Cells co-treated with NAC and As ₂ O ₃ showed increased intercellular spaces and lower cellular density compared with the control.

Conclusions  As ₂ O ₃ displayed a hormetic effect on pulpal cells; however, the proliferative effect induced by low As ₂ O ₃ concentrations should be interpreted with caution. NAC did not prevent As ₂ O ₃ -mediated toxicity; however, it demonstrated potential for ameliorating this toxicity.

Arsenic removal with zero-valent iron filters in Burkina Faso: Field and laboratory insights

Groundwater contaminated with geogenic arsenic (As) is frequently used as drinking water in Burkina Faso, despite adverse health effects. This study focused on testing low-cost filter systems based on zero-valent iron (ZVI), which have not yet been explored in West Africa for As removal. The active ZVI bed was constructed using small-sized iron nails, embedded between sand layers. Household filters were tested for nine months in a remote village relying on tube well water with As concentrations of 400-1350 μg/L. Daily filtered volumes were 40-60 L, with flow rates of ~10 L/h. In parallel, downscaled laboratory filter columns were run to find the best set-up for optimal As removal, with special attention given to the influence of input pH, flow rate and water/nail contact time. Arsenic removal efficiencies in the field were 60-80% in the first six months of operation. The laboratory experiments revealed that trapped air in the nail layer greatly lowered As removal due to preferential flow and decreased water/nail contact time. Measures taken to avoid trapped air led to a partial improvement in the field filters, but effluent As remained >50 μg/L. Similar structural modifications were however very successful in the laboratory columns, where As removal efficiencies were consistently >95% and effluent concentrations frequently <10 μg/L, despite inflow As >1000 μg/L. A constantly saturated nail bed and careful flow control is necessary for optimal As removal. Slow flow and longer pauses between filtrations are important for sufficient contact times and for transformation of brown amorphous Fe-hydroxides to dense magnetite with incorporated As(V). This preliminary study has shown that nail-based filters have the potential to achieve As removal >90% in a field context if conditions (filter bed saturation, flow rate, pauses between filtrations) are well controlled.

Mobility and redox transformation of arsenic during treatment of artificially recharged groundwater for drinking water production

In this study we investigate opportunities for reducing arsenic (As) to low levels, below 1 μg/L in produced drinking water from artificially infiltrated groundwater. We observe that rapid sand filtration is the most important treatment step for the oxidation and removal of As at water treatment plants which use artificially recharged groundwater as source. Removal of As is mainly due to As co-precipitation with Fe(III)(oxyhydr)oxides, which shows higher efficiency in rapid sand filter beds compared to aeration and supernatant storage. This is due to an accelerated oxidation of As(III) to As(V) in the filter bed which may be caused by the manganese oxides and/or As(III) oxidizing bacteria, as both are found in the coating of rapid sand filter media grains by chemical analysis and taxonomic profiling of the bacterial communities. Arsenic removal does not take place in treatment steps such as granular activated carbon filtration, ultrafiltration or slow sand filtration, due to a lack of hydrolyzing iron in their influent and a lack of adsorption affinity between As and the filtration surfaces. Further, we found that As reduction to below 1 μg/L can be effectively achieved at water treatment plants either by treating the influent of rapid sand filters by dosing potassium permanganate in combination with ferric chloride or by treating the effluent of rapid sand filters with ferric chloride dosing only. Finally, we observe that reducing the pH is an effective measure for increasing As co-precipitation with Fe(III)(oxyhydr)oxides, but only when the oxidized arsenic, As(V), is the predominant species in water.

Effects of Inorganic Arsenic on Human Prostate Stem-Progenitor Cell Transformation, Autophagic Flux Blockade, and NRF2 Pathway Activation

BACKGROUND

Inorganic arsenic (iAs) is an environmental toxicant associated with an increased risk of prostate cancer in chronically exposed populations worldwide. However, the biological mechanisms underlying iAs-induced prostate carcinogenesis remain unclear.

OBJECTIVES

We studied how iAs affects normal human prostate stem-progenitor cells (PrSPCs) and drives transformation and interrogated the molecular mechanisms involved.

METHODS

PrSPCs were enriched by spheroid culture from normal human primary or immortalized prostate epithelial cells, and their differentiation capability was evaluated by organoid culture. Microarray analysis was conducted to identify iAs-dysregulated genes, and lentiviral infection was used for stable manipulation of identified genes. Soft agar colony growth assays were applied to examine iAs-induced transformation. For in vivo study, PrSPCs mixed with rat urogenital sinus mesenchyme were grafted under the renal capsule of nude mice to generate prostatelike tissues, and mice were exposed to 5 ppm (∼65μM) iAs in drinking water for 3 months.

RESULTS

Low-dose iAs (1μM) disturbed PrSPC homeostasis in vitro, leading to increased self-renewal and suppressed differentiation. Transcriptomic analysis indicated that iAs activated oncogenic pathways in PrSPCs, including the KEAP1-NRF2 pathway. Further, iAs-exposed proliferative progenitor cells exhibited NRF2 pathway activation that was sustained in their progeny cells. Knockdown of NRF2 inhibited spheroid formation by driving PrSPC differentiation, whereas its activation enhanced spheroid growth. Importantly, iAs-induced transformation was suppressed by NRF2 knockdown. Mechanistically, iAs suppressed Vacuolar ATPase subunit VMA5 expression, impairing lysosome acidification and inhibiting autophagic protein degradation including p62, which further activated NRF2. In vivo, chronic iAs exposure activated NRF2 in both epithelial and stroma cells of chimeric human prostate grafts and induced premalignant events.

CONCLUSIONS

Low-dose iAs increased self-renewal and decreased differentiation of human PrSPCs by activating the p62-NRF2 axis, resulting in epithelial cell transformation. NRF2 is activated by iAs through specific autophagic flux blockade in progenitor cells, which may have potential therapeutic implications. https://doi.org/10.1289/EHP6471.

Arsenic reduction to <1 µg/L in Dutch drinking water

Arsenic (As) is a highly toxic element which naturally occurs in drinking water. In spite of substantial evidence on the association between many illnesses and chronic consumption of As, there is still a considerable uncertainty about the health risks due to low As concentrations in drinking water. In the Netherlands, drinking water companies aim to supply water with As concentration of <1 μg/L - a water quality goal which is tenfold more stringent than the current WHO guideline. This paper provides (i) an account on the assessed lung cancer risk for the Dutch population due to pertinent low-level As in drinking water and cost-comparison between health care provision and As removal from water, (ii) an overview of As occurrence and mobility in drinking water sources and water treatment systems in the Netherlands and (iii) insights into As removal methods that have been employed or under investigation to achieve As reduction to <1 µg/L at Dutch water treatment plants. Lowering of the average As concentration to <1μg/L in the Netherlands is shown to result in an annual benefit of 7.2-14 M€. This study has a global significance for setting drinking water As limits and provision of safe drinking water.

An overview of environmental arsenic issues and exposure risks in Uruguay

Evidence for low-dose health effects of Arsenic (As) in humans is still controversial and presents a major public health issue in several countries worldwide. It is not clear yet, whether there is a lower safe threshold for arsenic in drinking water among other possible sources such as food, below which, exposures are not harmful. In Uruguay, safe drinking water is supplied to 94% of the population by a state company (OSE) and As levels in workplaces and food are officially regulated. This paper aims to present and discuss the issues regarding arsenic exposure risks to the environment and human population, which are being addressed in a multidisciplinary manner in Uruguay since 2007. An overview is given on both the background and the current situation, presenting reports and research studies conducted on these problems by various academic, state, and private institutions that deal with regulations, surveillance, and health care. Scientific research on geogenic As levels in groundwater indicates As levels above those recommended by the WHO for drinking water (10 μg L^-1) in different Uruguayan aquifers. There is a lack of baseline studies concerning Uruguayan residents that are exposed to As in drinking water over time. Furthermore, there is a need for data on environmental chemical exposure that could be associated with disease or death in the country. In addition, only a few As risk exposure assessment studies in children, adults, and workers using biomarkers in urine are available. Furthermore, this paper presents As levels in a rice growing region and the spatial distribution of groundwater arsenic data compared to a national cancer atlas database as ongoing research advances. Multidisciplinary research projects and local future actions are also described. This contribution constitutes a first attempt to develop a feasible health risk assessment of low-dose arsenic exposure in this Latin-American country.

Using disability-adjusted life years to estimate the cancer risks of low-level arsenic in drinking water

Recent studies have shown that long-term exposure to low-level arsenic (<10 μg/L) may cause human health problems. However, the induced cancer risks and differences among multisite cancers have not been well-understood. In this study, the concentrations of low-level arsenic in drinking water in XP city, Northwest China were investigated. A health risk assessment was carried out for different age groups and exposure pathways based on Monte Carlo simulations and disability-adjusted life years (DALYs). The measured arsenic levels were in the range of 7.61-9.25 μg/L with a mean of 8.23 μg/L. For the public, the average total lifetime cancer risk was 3.87 × 10^-4, and the total DALYs estimation for all age groups was 20.58 person-year. The average individual DALYs lost was 3.35 × 10^-5 per person-year (ppy), which was 33.5 times the reference value (1.00 × 10^-6 ppy). The mortality burden had a considerably larger contribution (97.31%) to the total disease burden, and the 60-65-year age group exhibited the largest DALYs lost. Skin cancer exhibited the largest burden of 2.15 × 10^-5 ppy, followed by lung cancer (1.20 × 10^-5 ppy). This study might be useful for potential strategies of risk control and management in XP drinking water.

Probabilistic Human Health Risk Assessment of Heavy Metal Intake via Vegetable Consumption around Pb/Zn Smelters in Southwest China

Vegetable contamination in mining and smelting areas has resulted in high dietary intakes of heavy metals, which pose potential health risks to local residents. In this study, paired soil-vegetable samples were collected around Pb/Zn smelters in Southwest China. Probabilistic risks to local residents via vegetable consumption were evaluated with a Monte Carlo simulation. The mean concentrations of As, Cd, Cu, Pb, and Zn in the soils were 116.76, 3.59, 158.56, 196.96, and 236.74 mg/kg, respectively. About 38.18%, 58.49%, and 52.83% of the vegetable samples exceeded the maximum allowable concentrations for As, Cd, and Pb, respectively. The daily dietary intake of As, Cd, and Pb exceeded the provisional tolerable daily intakes for local residents, with children showing the highest intake via vegetable consumption. The percentages of the target hazard quotients of As, Cd, and Pb for local residents exceeding the safe value of one were about 95%, 50%, and 25%, respectively. The 95th percentiles of the hazard index for children, adolescents, and adults were 15.71, 11.15, and 9.34, respectively, indicating significant risks to local residents, especially children. These results highlight a need to develop effective strategies to reduce heavy metal contamination and exposure to protect human health.

Targeted Quantitative Proteomics Revealed Arsenite-induced Proteasomal Degradation of RhoB in Fibroblast Cells

Arsenic is a toxicant widely present in the environment. Previous epidemiological and animal studies support that arsenic exposure is associated with elevated incidences of lung and skin cancers. Therefore, it is important to understand the molecular mechanisms through which arsenite initiates malignant transformation of lung and skin tissues. Ras superfamily of small GTPases assumes a crucial role in many cellular processes including transcription, protein synthesis, and trafficking. In addition, small GTPase signaling is known to be altered in many types of cancer. By employing a multiple-reaction monitoring (MRM)-based targeted proteomic method, we found that the protein level of RhoB was substantially decreased in IMR90 human lung fibroblast cells upon a 12-h exposure to 5 μM NaAsO2. In addition, the protein level of ectopically expressed RhoB was found to decline in a dose-dependent manner upon arsenite exposure in HEK293T, HeLa, and GM00637 cells as well as that of endogenous RhoB protein in IMR90 cells. Moreover, the arsenite-elicited down-regulation of RhoB was found to arise from enhanced proteasomal degradation. Taken together, we demonstrated, for the first time, that exposure to arsenite could attenuate the protein expression of RhoB through proteasomal degradation.

Hormetic Dose Response of NaAsO2 on Cell Proliferation of Prostate Cells in Vitro: Implications for Prostate Cancer Initiation and Therapy

Sodium meta-arsenite (NaAsO₂) has been suggested to play a role both in initiation/progression of prostate cancer and as a future antiprostate cancer drug. We have studied the effects of NaAsO₂ on cell proliferation of prostate cancer and noncancer cells, breast cancer cells, and adrenocortical carcinoma cells in vitro. Further, we have investigated the effect of NaAsO₂ on the androgen receptor. We report that NaAsO₂ alters the cell proliferation of prostate cells, in a hormetic manner, by increasing cell proliferation at low concentrations and decreasing the cell proliferation at high concentrations. No activation of the androgen receptor was detected. We conclude that NaAsO₂ is able to increase cell proliferation of prostate cells in vitro at low concentrations, while it decreases cell viability at high concentrations. This novel finding has to be further addressed if NaAsO₂ should be developed into an antiprostate cancer drug.

Biomonitoring of metals and trace elements in urine of central Ethiopian populations

Biomonitoring of chemical concentrations in humans is important for detecting, monitoring, and addressing a wide range of health threats. However, it is virtually absent across many African nations, including Ethiopia. This study aims to determine urinary concentrations for metals and trace elements in populations living in the central Ethiopian Rift Valley. The region is unindustralized, rural, and characterized by unique geologic rifting and volcanic activities that have produced vast pyroclastic materials, forming its aquifer and fertile agricultural soils. Millions of people in the region rely on wells for drinking water and are engaged in cereal-based subsistence agriculture. We enrolled a total of 386 residents aged 10-50 years old (201 females and 185 males). The levels of 23 elements except F^─ were quantified in water and urine samples by ICP-MS. Mean concentrations of B, F^─, Ca, and Mg were measured in mg/L levels, while concentrations of Mo, Zn, Sr, Rb, and Li ranged between 100 and 700 μg/L. Mean concentrations between 5 and 15 μg/L were found for Ni, Cu, and Mn, while Ag, Be, Cd, Co, Pb, Sb, Th, TI, and U were all below 5 μg/L. Arsenic and Al had mean concentrations between 30 and 50 μg/L. Mean urinary concentrations of Ca, Cu, Mg, Pb, Sr, and Zn were significantly higher in males than females, whereas Co and Mn were higher in females. Finally, younger individuals (10-30 years) had significantly higher mean concentrations of B, Cd, Co, Mg, Mo, and Pb than those between 31 and 50 years, whereas only Ca was higher in the older age group. The concentration ranges of B, Mo, Mn, TI, Li, Zn, and in particular F^─ (0.44-44.6 mg/L) and As (2.2-164 μg/L) in urine were higher than the reference ranges reported in healthy unexposed North American and European populations, while those for the remaining 16 elements were comparable to published reference ranges from such settings. The established concentration ranges are important to monitor future changes in exposure, and risk factors for disease, that might stem from the economic growth and industrialization that is currently underway in the region.

Arsenic in groundwater in private wells in rural North Dakota and South Dakota: Water quality assessment for an intervention trial

Elevated exposure to arsenic disproportionately affects populations relying on private well water in the United States (US). This includes many American Indian (AI) communities where naturally occurring arsenic is often above 10 µg/L, the current US Environmental Protection Agency safety standard. The Strong Heart Water Study is a randomized controlled trial aiming to reduce arsenic exposure to private well water users in AI communities in North Dakota and South Dakota. In preparation for this intervention, 371 households were included in a community water arsenic testing program to identify households with arsenic ≥10 µg/L by inductively coupled plasma mass spectrometry (ICP-MS). Arsenic ≥10 µg/L was found in 97/371 (26.1%) households; median water arsenic concentration was 6.3 µg/L, ranging from <1-198 µg/L. Silica was identified as a water quality parameter that could impact the efficacy of arsenic removal devices to be installed. A low-range field rapid arsenic testing kit evaluated in a small number of households was found to have low accuracy; therefore, not an option for the screening of affected households in this setting. In a pilot study of the effectiveness of a point-of-use adsorptive media water filtration device for arsenic removal, all devices installed removed arsenic below 1 µg/L at both installation and 9 months post-installation. This study identified a relatively high burden of arsenic in AI study communities as well as an effective water filtration device to reduce arsenic in these communities. The long-term efficacy of a community based arsenic mitigation program in reducing arsenic exposure and preventing arsenic related disease is being tested as part of the Strong Heart Water Study.

A Comprehensive Review of Arsenic Exposure and Risk from Rice and a Risk Assessment among a Cohort of Adolescents in Kunming, China

Inorganic arsenic (iAs) is carcinogenic and highly concentrated in rice. Dietary exposure to iAs is concerning among adolescents due to their developmental stage and iAs’s long-latency effects. This paper aimed to assess iAs exposure from rice and related lifetime cancer risks (LCR) among adolescents in Kunming, China. A comprehensive literature review of iAs levels in rice and LCR in humans was also conducted. Average daily consumption of rice (ADC) was estimated from 267 adolescents (15–18 years). Rice samples obtained from 6 markets were analyzed for iAs concentration (AC). Estimated daily intake (EDI) of iAs was calculated using ADC, AC, and average body weight (BW). Lifetime Cancer Risk (LCR) was calculated using EDI and U.S. EPA derived iAs oral slope factor. The AC was 0.058 mg/kg and the average BW and ADC were 67.5 kg and 410 g/day for males and 55.5 kg and 337 g/day for females. The EDI and LCR were 3.52 × 10⁻⁴ mg/kg-BW/day and 5.28 × 10⁻⁴ for both males and females, with LCR 5 times above the U.S. LCR upper limit of 1.0 × 10⁻⁴. While the AC was below the Chinese maximum contaminant level of 0.2 mg/kg, study results indicated that Kunming adolescents may be at increased risk for iAs-related cancers.

Low-Dose Arsenic Trioxide Modulates the Differentiation of Mouse Embryonic Stem Cells

Arsenic (As) is a well-known environmental pollutant, while arsenic trioxide (ATO) has been proven to be an effective treatment for acute promyelocytic leukemia, however, the mechanism underlying its dual effects is not fully understood. Embryonic stem cells (ESCs) exhibit properties of stemness and serve as a popular model to investigate epigenetic modifiers including environmental pollutants. Herein, the effects of low-dose ATO on differentiation were evaluated in vitro using a mouse ESCs (mESCs) cell line, CGR8. Cells treated with 0.2-0.5 μM ATO for 3-4 days had slight inhibition of proliferation with elevation of apoptosis, but obvious alterations of differentiation by morphological checking and alkaline phosphatase (AP) staining. Moreover, ATO exposure significantly decreased the mRNA expression of the stemness maintenance genes including Oct4, Nanog, and Rex-1 ( P < 0.01), whereas obviously increased some tissue-specific differentiation marker genes such as Gata4, Gata-6, AFP, and IHH. These alterations were consistent with the differentiation phenotype induced by retinoic acid (RA) and the expression patterns of distinct pluripotency markers such as SSEA-1 and Oct4. Furthermore, low-dose ATO led to a quantitative increase in Caspase 3 (CASP3) activation and subsequent cleavage of Nanog around 27 kDa, which corresponded with the mouse Nanog cleaved by CASP3 in a tube cleavage assay. Taken together, we suggest that low-dose ATO exposure will induce differentiation, other than apoptosis, of ESCs, such effects might be tuned partially by ATO-induced CASP3 activation and Nanog cleavage coupling with other differentiation related genes involved. The present findings provide a preliminary action mechanism of arsenic on the cell fate determination.

Estimating the risk of bladder and kidney cancer from exposure to low-levels of arsenic in drinking water, Nova Scotia, Canada

Arsenic in drinking water impacts health. Highest levels of arsenic have been historically observed in Taiwan and Bangladesh but the contaminant has been affecting the health of people globally. Strong associations have been confirmed between exposure to high-levels of arsenic in drinking water and a wide range of diseases, including cancer. However, at lower levels of exposure, especially near the current World Health Organization regulatory limit (10μg/L), this association is inconsistent as the effects are mostly extrapolated from high exposure studies. This ecological study used Bayesian inference to model the relative risk of bladder and kidney cancer at these lower concentrations-0-2μg/L; 2-5μg/L and; ≥5μg/L of arsenic-in 864 bladder and 525 kidney cancers diagnosed in the study area, Nova Scotia, Canada between 1998 and 2010. The model included proxy measures of lifestyle (e.g. smoking) and accounted for spatial dependencies. Overall, bladder cancer risk was 16% (2-5μg/L) and 18% (≥5μg/L) greater than that of the referent group (<2μg/L), with posterior probabilities of 88% and 93% for these risks being above 1. Effect sizes for kidney cancer were 5% (2-5μg/L) and 14% (≥5μg/L) above that of the referent group (<2μg/L), with probabilities of 61% and 84%. High-risk areas were common in southwestern areas, where higher arsenic-levels are associated with the local geology. The study suggests an increased bladder cancer, and potentially kidney cancer, risk from exposure to drinking water arsenic-levels within the current the World Health Organization maximum acceptable concentration.

A dose-response meta-analysis of chronic arsenic exposure and incident cardiovascular disease

Background

Consistent evidence at high levels of water arsenic (≥100 µg/l), and growing evidence at low-moderate levels (<100 µg/l), support a link with cardiovascular disease (CVD). The shape of the dose-response across low-moderate and high levels of arsenic in drinking water is uncertain and critical for risk assessment.

Methods

We conducted a systematic review of general population epidemiological studies of arsenic and incident clinical CVD (all CVD, coronary heart disease (CHD) and stroke) with three or more exposure categories. In a dose-response meta-analysis, we estimated the pooled association between log-transformed water arsenic (log-linear) and restricted cubic splines of log-transformed water arsenic (non-linear) and the relative risk of each CVD endpoint.

Results

Twelve studies (pooled N = 408 945) conducted at high (N = 7) and low-moderate (N = 5) levels of water arsenic met inclusion criteria, and 11 studies were included in the meta-analysis. Compared with 10 µg/l, the estimated pooled relative risks [95% confidence interval (CI)] for 20 µg/l water arsenic, based on a log-linear model, were 1.09 (1.03, 1.14) (N = 2) for CVD incidence, 1.07 (1.01, 1.14) (N = 6) for CVD mortality, 1.11 (1.05, 1.17) (N = 4) for CHD incidence, 1.16 (1.07, 1.26) (N = 6) for CHD mortality, 1.08 (0.99, 1.17) (N = 2) for stroke incidence and 1.06 (0.93, 1.20) (N = 6) for stroke mortality. We found no evidence of non-linearity, although these tests had low statistical power.

Conclusions

Although limited by the small number of studies, this analysis supports quantitatively including CVD in inorganic arsenic risk assessment, and strengthens the evidence for an association between arsenic and CVD across low-moderate to high levels.

Arsenic exposure impels CD4 commitment in thymus and suppress T cell cytokine secretion by increasing regulatory T cells

Arsenic is globally infamous for inducing immunosuppression associated with prevalence of opportunistic infection in exposed population, although the mechanism remains elusive. In this study, we investigate the effect of arsenic exposure on thymocyte lineage commitment and the involvement of regulatory T cells (T_reg) in arsenic-induced immunosuppression. Male Balb/c mice were exposed to 0.038, 0.38 and 3.8 ppm sodium arsenite for 7, 15 and 30 days through oral gavage. Arsenic exposure promoted CD4 lineage commitment in a dose dependent manner supported by the expression of ThPOK in thymus. Arsenic also increased splenic CD4⁺ T cells and promoted their differentiation into T_reg cells. In parallel, arsenic exposure induced immunosuppression characterized by low cytokine secretion from splenocytes and increased susceptibility to Mycobacterium fortuitum (M. fortuitum) infection. Therefore, we linked arsenic-induced rise in T_reg cells with suppressed T_h1 and T_h2 related cytokines, which has been reversed by inhibition of T_reg cells in-vivo using wortmannin. Other parameters like body weight, kidney and liver function, histoanatomy of thymus and spleen as well as thymocyte and splenocytes viability were unaltered by arsenic exposure. Taken together our findings indicated that environmentally relevant dose of arsenic enhanced differentiation of T_reg cells which in turn induce immunosuppression in experimental animals.

Chronic arsenic exposure and risk of carotid artery disease: The Strong Heart Study

BACKGROUND

Inorganic arsenic exposure from naturally contaminated groundwater is related to vascular disease. No prospective studies have evaluated the association between arsenic and carotid atherosclerosis at low-moderate levels. We examined the association of long-term, low-moderate inorganic arsenic exposure with carotid arterial disease.

METHODS

American Indians, 45-74 years old, in Arizona, Oklahoma, and North and South Dakota had arsenic concentrations (sum of inorganic and methylated species, μg/g urine creatinine) measured from baseline urine samples (1989-1991). Carotid artery ultrasound was performed in 1998-1999. Vascular disease was assessed by the carotid intima media thickness (CIMT), the presence of atherosclerotic plaque in the carotid, and by the number of segments containing plaque (plaque score).

RESULTS

2402 participants (mean age 55.3 years, 63.1% female, mean body mass index 31.0kg/m², diabetes 45.7%, hypertension 34.2%) had a median (interquintile range) urine arsenic concentration of 9.2 (5.00, 17.06) µg/g creatinine. The mean CIMT was 0.75mm. 64.7% had carotid artery plaque (3% with >50% stenosis). In fully adjusted models comparing participants in the 80th vs. 20th percentile in arsenic concentrations, the mean difference in CIMT was 0.01 (95% confidence interval (95%CI): 0.00, 0.02) mm, the relative risk of plaque presence was 1.04 (95%CI: 0.99, 1.09), and the geometric mean ratio of plaque score was 1.05 (95%CI: 1.01, 1.09).

CONCLUSIONS

Urine arsenic was positively associated with CIMT and increased plaque score later in life although the association was small. The relationship between urinary arsenic and the presence of plaque was not statistically significant when adjusted for other risk factors. Arsenic exposure may play a role in increasing the severity of carotid vascular disease.

Inorganic Arsenic Determination in Food: A Review of Analytical Proposals and Quality Assessment Over the Last Six Years

Here we review recent developments in analytical proposals for the assessment of inorganic arsenic (iAs) content in food products. Interest in the determination of iAs in products for human consumption such as food commodities, wine, and seaweed among others is fueled by the wide recognition of its toxic effects on humans, even at low concentrations. Currently, the need for robust and reliable analytical methods is recognized by various international safety and health agencies, and by organizations in charge of establishing acceptable tolerance levels of iAs in food. This review summarizes the state of the art of analytical methods while highlighting tools for the assessment of quality assessment of the results, such as the production and evaluation of certified reference materials (CRMs) and the availability of specific proficiency testing (PT) programmes. Because the number of studies dedicated to the subject of this review has increased considerably over recent years, the sources consulted and cited here are limited to those from 2010 to the end of 2015.

Arsenic Uptake by Muskmelon (Cucumis melo) Plants from Contaminated Water

Arsenic is a carcinogenic element that occurs naturally in the environment. High levels of arsenic are found in water in some parts of the world, including Texas. The aims of this study were to determine the distribution of arsenic in muskmelon (Cucumis melo) plants accumulated from arsenic spiked water and to observe effects on plant biomass. Plants were grown and irrigated using water spiked with variable concentrations of arsenic. Inductively coupled plasma mass spectrometry was used to quantify arsenic in different parts of the plant and fruit. Under all conditions tested in this study, the highest concentrations of arsenic were found in the leaves, soil, and roots. Arsenic in the water had no significant effect on plant biomass. Fruits analyzed in this study had arsenic concentrations of 101 μg/kg or less. Consuming these fruits would result in less arsenic exposure than drinking water at recommended levels.

Association of Children's Urinary CC16 Levels with Arsenic Concentrations in Multiple Environmental Media

Arsenic exposure has been associated with decreased club cell secretory protein (CC16) levels in adults. Further, both arsenic exposure and decreased levels of CC16 in childhood have been associated with decreased adult lung function. Our objective was to determine if urinary CC16 levels in children are associated with arsenic concentrations in environmental media collected from their homes. Yard soil, house dust, and tap water were taken from 34 homes. Urine and toenail samples were collected from 68 children. All concentrations were natural log-transformed prior to data analysis. There were associations between urinary CC16 and arsenic concentration in soil (b = -0.43, p = 0.001, R² = 0.08), water (b = -0.22, p = 0.07, R² = 0.03), house dust (b = -0.37, p = 0.07, R² = 0.04), and dust loading (b = -0.21, p = 0.04, R² = 0.04). In multiple analyses, only the concentration of arsenic in soil was associated with urinary CC16 levels (b = -0.42, p = 0.02, R² = 0.14 (full model)) after accounting for other factors. The association between urinary CC16 and soil arsenic may suggest that localized arsenic exposure in the lungs could damage the airway epithelium and predispose children for diminished lung function. Future work to assess this possible mechanism should examine potential associations between airborne arsenic exposures, CC16 levels, lung function, and other possible confounders in children in arsenic-impacted communities.

Health risks of children's cumulative and aggregative exposure to metals and metalloids in a typical urban environment in China

Rapid development of industrialization and urbanization results in serious environmental contamination by metal(loid)s, which would consequently cause deleterious health effects to the exposed people through multi-pathways. Therefore, total health risk assessment for the population in urban environment is very important. Unfortunately, few studies to date investigate the cumulative health risks of metal(loid)s through aggregative pathways in Children who are often susceptible population. 12 metal(loid)s including Lead(Pb), Cadmium(Cd), Arsenic(As), Chromium(Cr), Zinc(Zn), Copper(Cu), Nickel(Ni), Manganese(Mn), Cobalt(Co), Selenium(Se), Antimony(Se) and Vanadium(V), were analyzed in PM10, drinking water, food, soil and indoor dust in this study. The cumulative and aggregative risks of these metal(loid)s among the local children were then evaluated on a field sampling and questionnaire-survey basis. The results showed that the environments were heavily polluted by metal(loid)s. For most metal(loid)s, food ingestion accounted for more than 80% of the total daily exposure dose. The non-cancer risks were up to 30 times higher than the acceptable level due to the food ingestion via Pb, Cr, Cu, Zn, As, Se, Cd and Sb, and the PM10 inhalation via Cr and Mn. While, the cancer risks were mainly attributed to Cr via food ingestion and As via food and dust ingestion, and approximately 100 times of the maximum acceptable level of 1.0 × 10(-4). The study highlights the cumulative and aggregative exposure assessment, instead of pollutant investigation to evaluate the potential health risks and emphasizes concerns to improve indoor hygienic and environmental quality and to decrease the potential harmful health effects of children living in urban area.

NADPH Oxidase-Dependent Mechanism Explains How Arsenic and Other Oxidants Can Activate Aryl Hydrocarbon Receptor Signaling

The mechanisms explaining arsenic toxicity are not well understood, but physiological consequences of stimulated aryl hydrocarbon receptor (AHR) signaling both directly and through cross-talk with other pathways have been indicated. The aim of this study was to establish how arsenic interacts with AHR-mediated transcription. The human hepatoma cell line (HepG2-XRE-Luc) carrying a luciferase reporter under the control of two AHR response elements (AHREs) and immortalized human keratinocytes (HaCaT) were exposed to sodium arsenite (NaAsO2; As(3+)), alone or in combination with the endogenous high affinity AHR ligand 6-formylindolo[3,2-b]carbazole (FICZ). Luciferase activity, cytochrome P4501A1 (CYP1A1) activity, oxidative stress-related responses, metabolic clearance of FICZ, and NADPH oxidase (NOX) activity as well as nuclear factor (erythroid-derived 2)-like 2 (Nrf2)-dependent gene expression were measured. Arsenic inhibited CYP1A1 enzyme activity and reduced the metabolic clearance of FICZ. Arsenic also led to activated CYP1A1 transcription but only in cells grown in medium containing trace amounts of the endogenous ligand FICZ, pointing to an indirect mechanism of activation. Initially, arsenic caused dose-dependent inhibition of FICZ-activated AHR signaling, disturbed intracellular GSH status, and increased expression of oxidative stress-related genes. Silencing of NOX4, addition of N-acetylcystein, or pretreatment with arsenic itself attenuated the initial dose-dependent inhibition of AHR signaling. Arsenic pretreatment led to elevated GSH levels and sensitized the cells to ligand-dependent AHR signaling, while silencing of Nrf2 significantly reduced arsenic-mediated activation of the AHR. In addition, influence of NOX on AHR activation was also observed in cells treated with the SH-reactive metals cadmium, mercury, and nickel. Together, the results suggest that SH-reactive agents via a new and possibly general NOX/H2O2-dependent mechanism can interfere with the endogenous regulation of the AHR.

Environmental factors in cardiovascular disease

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

Arsenic in Drinking Water and Mortality for Cancer and Chronic Diseases in Central Italy, 1990-2010

BACKGROUND

In several volcanic areas of Italy, arsenic levels exceed European regulatory limits (10 μg/L in drinking water). There is still uncertainty about health risks from arsenic at low-medium doses (<100 μg/L).

OBJECTIVES

A large population-based study using an administrative cohort of residents in the Viterbo province (Central Italy), chronically exposed to low-medium arsenic levels via drinking water, was investigated to evaluate the effects of a lifetime exposure to arsenic on mortality from cancers and chronic diseases.

METHODS

The study population consisted of 165,609 residents of 17 municipalities, followed from 1990 until 2010. Average individual arsenic exposure at the first residence (AsI) was estimated through a space-time modeling approach using residential history and arsenic concentrations from water supply. A time-dependent Cumulative Arsenic dose Indicator (CAI) was calculated, accounting for daily water intake and exposure duration. Mortality Hazard Ratios (HR) were estimated by gender for different diseases using Cox proportional models, adjusting for individual and area-level confounders. A flexible non-parametric approach was used to investigate dose-response relationships.

RESULTS

Mean AsI exposure was 19.3 μg/L, and average exposure duration was 39.5 years. Associations of AsI and CAI indicators with several diseases were found, with greatest risks found for lung cancer in both sexes (HR = 2.61 males; HR = 2.09 females), myocardial infarction, peripheral arterial disease and COPD in males (HR = 2.94; HR = 2.44; HR = 2.54 respectively) and diabetes in females (HR = 2.56). For lung cancer and cardiovascular diseases dose-response relationship is modelled by piecewise linear functions revealing effects even for doses lower than 10 μg/L, and no threshold dose value was identified as safe for health.

CONCLUSIONS

Results provide new evidence for risk assessment of low-medium concentrations of arsenic and contribute to the ongoing debate about the threshold-dose of effect, suggesting that even concentrations below 10 μg/L carry a mortality risk. Policy actions are urgently needed in areas exposed to arsenic like in the Viterbo province, to comply with current EU regulations.

MDI Biological Laboratory Arsenic Summit: Approaches to Limiting Human Exposure to Arsenic

This report is the outcome of the meeting "Environmental and Human Health Consequences of Arsenic" held at the MDI Biological Laboratory in Salisbury Cove, Maine, August 13-15, 2014. Human exposure to arsenic represents a significant health problem worldwide that requires immediate attention according to the World Health Organization (WHO). One billion people are exposed to arsenic in food, and more than 200 million people ingest arsenic via drinking water at concentrations greater than international standards. Although the US Environmental Protection Agency (EPA) has set a limit of 10 μg/L in public water supplies and the WHO has recommended an upper limit of 10 μg/L, recent studies indicate that these limits are not protective enough. In addition, there are currently few standards for arsenic in food. Those who participated in the Summit support citizens, scientists, policymakers, industry, and educators at the local, state, national, and international levels to (1) establish science-based evidence for setting standards at the local, state, national, and global levels for arsenic in water and food; (2) work with government agencies to set regulations for arsenic in water and food, to establish and strengthen non-regulatory programs, and to strengthen collaboration among government agencies, NGOs, academia, the private sector, industry, and others; (3) develop novel and cost-effective technologies for identification and reduction of exposure to arsenic in water; (4) develop novel and cost-effective approaches to reduce arsenic exposure in juice, rice, and other relevant foods; and (5) develop an Arsenic Education Plan to guide the development of science curricula as well as community outreach and education programs that serve to inform students and consumers about arsenic exposure and engage them in well water testing and development of remediation strategies.

Arsenic: A Review of the Element's Toxicity, Plant Interactions, and Potential Methods of Remediation

Arsenic is a naturally occurring element with a long history of toxicity. Sites of contamination are found worldwide as a result of both natural processes and anthropogenic activities. The broad scope of arsenic toxicity to humans and its unique interaction with the environment have led to extensive research into its physicochemical properties and toxic behavior in biological systems. The purpose of this review is to compile the results of recent studies concerning the metalloid and consider the chemical and physical properties of arsenic in the broad context of human toxicity and phytoremediation. Areas of focus include arsenic's mechanisms of human toxicity, interaction with plant systems, potential methods of remediation, and protocols for the determination of metals in experimentation. This assessment of the literature indicates that controlling contamination of water sources and plants through effective remediation and management is essential to successfully addressing the problems of arsenic toxicity and contamination.

Association of hypothyroidism with low-level arsenic exposure in rural West Texas

It has been reported recently that a higher airborne arsenic level was correlated with higher urinary arsenic concentration and lower serum thyroxin level among urban policemen and rural highway workmen in Italy. The current study was to determine whether exposure to low-level arsenic groundwater (2-22µg/L) is associated with hypothyroidism among 723 participants (118 male and 267 female Hispanics; 108 male and 230 female non-Hispanic whites, NHW) living in rural West Texas counties. Arsenic and iodine levels in their groundwater used for drinking and or cooking were estimated by the inverse distance weighted (IDW) interpolation technique. Groundwater arsenic was ≥8µg/L in 36% of the subjects' wells while iodine concentration was <1µg/L in 91% of their wells. Logistic regression analysis showed that arsenic in groundwater ≥8µg/L and cumulative arsenic exposure (groundwater arsenic concentration multiplied by the number of years living in the current address) but not groundwater iodine concentration were significant predictors for hypothyroidism among Hispanics (p<0.05) but not NHW after adjusting for covariates such as age, gender, annual household income and health insurance coverage. The ethnic difference may be due to a marginally higher percentage of Hispanics (p=0.0622) who lived in areas with groundwater arsenic ≥8µg/L compared with NHW. The prevalence of hypothyroidism was significantly higher in Hispanics or NHW of this rural cohort than the national prevalence. Measures should be taken to reduce arsenic in drinking water in order to prevent hypothyroidism in rural areas.