Lung inflammation biomarkers and lung function in children chronically exposed to arsenic

Organochlorine pesticide residues and urinary arsenic and fluoride levels in mothers and their newborns who are residents of rural areas in Durango State, Mexico

Maternal and prenatal exposure to organochlorine pesticides (OCP), arsenic (As), and fluoride (F-) is a critical public health concern. The present study assessed serum OCP residues and urinary As and F- levels in mother and newborn pairs who are residents of rural areas of Durango State, Mexico, from August 2018 to February 2019. Levels of OCP, As, and F- were measured in serum and urine samples by Gas chromatography - Tandem mass spectrometry (GC - MS/MS), Hydride generation - Atomic fluorescent spectrometry (HG-AFS, and ion-selective electron analysis (ISE), respectively, in 60 binomial mothers - newborns. Dieldrin, endrin aldehyde, and endosulfan-II were significantly higher in newborns than in mothers (p ˂0.05). Meanwhile, no significant differences were observed for As and F- concentrations between mother - newborn pairs. Differences were observed in ∑Dienes and ∑DDTs comparing newborns with normal and low birth weights and a positive relationship in ƩDienes, ƩChlordanes, and ƩDDTs between mother and newborn pairs (p ˂ 0.05). These findings highlight the importance of extensive research regarding the influence of pollution.

Arsenic exposure and pulmonary function decline: Potential mediating role of TRAIL in chronic obstructive pulmonary disease patients

BACKGROUND

Environmental arsenic (As) exposure is strongly related to the progression of chronic obstructive pulmonary disease (COPD). Pulmonary epithelial cells apoptosis is implicated in the pathophysiological mechanisms of COPD. However, the role of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), one biomarker of apoptosis, remains unclear in As-mediated pulmonary function alternations in COPD patients.

METHODS

This study included 239 COPD patients. The serum level of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) was measured by enzyme-linked immunosorbent assay (ELISA). The blood As level was determined through inductively coupled plasma mass spectrometry (ICP-MS).

RESULTS

Blood As levels exhibited a negative and dose-dependent correlation with pulmonary function. Per unit elevation of blood arsenic concentrations was related to reductions of 0.339 L in FEV1, 0.311 L in FVC, 1.171% in FEV1/FVC%, and 7.999% in FEV1% in COPD subjects. Additionally, a positive dose-response correlation of blood As with serum TRAIL was found in COPD subjects. Additionally, the level of serum TRAIL was negatively linked to lung function. Elevated TRAIL significantly mediated As-induced decreases of 11.05%, 13.35%, and 31.78% in FVC, FEV1, and FEV1%, respectively among the COPD patients.

CONCLUSION

Blood As level is positively correlated with pulmonary function decline and serum TRAIL increase in individuals with COPD. Our findings suggest that elevated TRAIL levels may serve as a mediating mechanism through which As contributes to declining lung function in COPD patients.

The disruption of blood-brain barrier induced by long-term arsenic exposure is associated with the increase of MMP-9 and MMP-2: The characteristics are similar to those caused by senescence

Accumulating evidence suggests that Matrix metalloproteinase-9 (MMP-9) and -2 (MMP-2) are involved in the neuropathological processes by contributing to breaking the extracellular matrix and the tight junctions that constitute the blood-brain barrier (BBB). However, the influences of arsenic (As) on these two MMPs were inconsistent. In the cross-sectional study of 500 adults, serum MMP-2 and MMP-9 positively correlated with urine arsenic. And the positive correlation between urine tAs and serum MMP-9/2 was found in people older than 59 years. In vivo studies, we found that arsenic exposure or senescence might decrease number of neurons and neuritic density and increase serum and cortical MMP-9/2 levels. Furthermore, arsenic exposure or senescence could disrupt the tight junction of BBB and elevate MMP-9 and MMP-2 expression in the cerebral microvascular endothelium. The MMP-9 and MMP-2 are of particular interest when researching the link between arsenic exposure and nerve damage.

Effect of Gestational Pesticide Exposure on the Child's Respiratory System: A Narrative Review

BACKGROUND

In recent years, concern has arisen worldwide about the potential adverse effects that could result from early-life exposure to pesticides. Asthma, bronchitis, and persistent cough in children have been linked to gestational exposure to pesticides. The respiratory effects of gestational exposure to pesticides are controversial. The aim of this study was to determine the relationship between pesticide exposure in pregnant women and its effect on the respiratory system of their children.

METHODS

A narrative review was carried out by means of a search in the main databases.

RESULTS

Findings of studies confirmed the effects of pesticides on the child's health. These substances cross the placenta and become transmitters of exposure to the individual at the most sensitive stage of her development.

CONCLUSIONS

Chronic exposure to pesticides in fetuses is associated with chronic respiratory symptoms and disease.

Arsenic Induces M2 Macrophage Polarization and Shifts M1/M2 Cytokine Production via Mitophagy

Arsenic is an environmental factor associated with epithelial-mesenchymal transition (EMT). Since macrophages play a crucial role in regulating EMT, we studied the effects of arsenic on macrophage polarization. We first determined the arsenic concentrations to be used by cell viability assays in conjunction with previous studies. In our results, arsenic treatment increased the alternatively activated (M2) macrophage markers, including arginase 1 (ARG-1) gene expression, chemokine (C-C motif) ligand 16 (CCL16), transforming growth factor-β1 (TGF-β1), and the cluster of differentiation 206 (CD206) surface marker. Arsenic-treated macrophages promoted A549 lung epithelial cell invasion and migration in a cell co-culture model and a 3D gel cell co-culture model, confirming that arsenic treatment promoted EMT in lung epithelial cells. We confirmed that arsenic induced autophagy/mitophagy by microtubule-associated protein 1 light-chain 3-II (LC3 II) and phosphor-Parkin (p-Parkin) protein markers. The autophagy inhibitor chloroquine (CQ) recovered the expression of the inducible nitric oxide synthase (iNOS) gene in arsenic-treated M1 macrophages, which represents a confirmation that arsenic indeed induced the repolarization of classically activated (M1) macrophage to M2 macrophages through the autophagy/mitophagy pathway. Next, we verified that arsenic increased M2 cell markers in mouse blood and lungs. This study suggests that mitophagy is involved in the arsenic-induced M1 macrophage switch to an M2-like phenotype.

Arsenic exposure and respiratory outcomes during childhood in the INMA study

Ingested inorganic arsenic (iAs) is a human carcinogen that is also linked to other adverse health effects, such as respiratory outcomes. Yet, among populations consuming low-arsenic drinking water, the impact of iAs exposure on childhood respiratory health is still uncertain. For a Spanish child study cohort (INfancia y Medio Ambiente—INMA), low-arsenic drinking water is usually available and ingestion of iAs from food is considered the major source of exposure. Here, we explored the association between iAs exposure and children’s respiratory outcomes assessed at 4 and 7 years of age (n = 400). The summation of 4-year-old children’s urinary iAs, monomethylarsonic acid (MMA), and dimethylarsinic acid (DMA) was used as a biomarker of iAs exposure (∑As) (median of 4.92 μg/L). Children’s occurrence of asthma, eczema, sneeze, wheeze, and medication for asthma and wheeze at each assessment time point (i.e., 4- and 7-year) was assessed with maternal interviewer-led questionnaires. Crude and adjusted Poisson regression models using Generalized Estimating Equation (GEE) were performed to account for the association between natural logarithm transformed (ln) urinary ∑As in μg/L at 4 years and repeated assessments of respiratory symptoms at 4 and 7 years of age. The covariates included in the models were child sex, maternal smoking status, maternal level of education, sub-cohort, and children’s consumption of vegetables, fruits, and fish/seafood. The GEE—splines function using Poisson regression showed an increased trend of the overall expected counts of respiratory symptoms with high urinary ∑As. The adjusted expected counts (95% confidence intervals) at ln-transformed urinary ∑As 1.57 (average concentration) and 4.00 (99^th percentile concentration) were 0.63 (0.36, 1.10) and 1.33 (0.61, 2.89), respectively. These exploratory findings suggest that even relatively low-iAs exposure levels, relevant to the Spanish and other populations, may relate to an increased number of respiratory symptoms during childhood.

Non-malignant respiratory illness associated with exposure to arsenic compounds in the environment

Arsenic (As), a toxic metalloid, primarily originates from both natural and anthropogenic activities. Reports suggested that millions of people globally exposed to high levels of naturally occurring As compounds via inhalation and ingestion. There is evidence that As is a well-known lung carcinogen. However, there has been relatively little evidence suggesting its non-malignant lung effects. This review comprehensively summarises current experimental and clinical studies implicating the association of As exposure and the development of several non-malignant lung diseases. Experimental studies provided evidence that As exposure induces redox imbalance, apoptosis, inflammatory response, epithelial-to-mesenchymal transition (EMT), and affected normal lung development through alteration of the components of intracellular signaling cascades. In addition, we also discuss the sources and possible mechanisms of As influx and efflux in the lung. Finally, current experimental studies on treatment strategies using phytochemicals and our perspective on future research with As are also discussed.

Arsenic-induced lung inflammation and fibrosis in a rat model: Contribution of the HMGB1/RAGE, PI3K/AKT, and TGF-β1/SMAD pathways

An increasing number of studies have shown that arsenic exposure increases the risk of lung cancer as well as a variety of non-malignant respiratory diseases, including bronchitis and tracheobronchitis. HMGB1 is widely expressed in a variety of tissues and cells and is involved in the pathological processes of many lung diseases through binding to the corresponding receptors and activating the downstream signaling pathways. However, the exact role of HMGB1/RAGE in arsenic-induced lung injury remains unknown. The aim of this study was to investigate whether HMGB1/RAGE and its activated downstream pathways are involved in the process of arsenic exposure-induced lung injury in rats. In this study, an animal model of oral exposure to arsenic was induced using 2.5, 5 and 10 mg/kg NaAsO2. The results showed that capillary permeability (LDH, TP, ACP, and AKP) was increased in the arsenic exposure groups, resulting in cell damage; this was accompanied by acute inflammation marked by significant neutrophil infiltration. Meanwhile, obvious histopathological damage, including thickening of the lung epithelium, increased infiltration of inflammatory cells, rupture of the alveolar wall, swelling of the mitochondria, and chromatin agglutination was observed by H&E staining and transmission electron microscopy. Furthermore, the results confirmed that the expressions of HMGB1 and RAGE in lung tissue were enhanced, and protein expression of PI3K, p-AKT, IL-1β, IL-18, and MMP-9 was increased in lung homogenates from the arsenic-exposed groups compared to the control group. Finally, Masson's staining results revealed arsenic-induced fibrosis and collagen deposition. Moreover, a significant increase in key fibrosis factors, including TGF-β1, p-SMAD2, p-SMAD3, and SMAD4 was observed in the lung homogenates in arsenic-exposed groups. In conclusion, the current study demonstrates that sub-chronic arsenic exposure triggers the inflammatory response and collagen fiber deposition in rat lung tissue. The potential mechanism may be closely related to activation of the pro-inflammatory-related HMGB1/RAGE pathway and initiation of the PI3K/AKT and TGF-β1/SMAD pathways.

Lung developmental is altered after inhalation exposure to various concentrations of calcium arsenate

Exposure to dust from active and abandoned mining operations may be a very significant health hazard, especially to sensitive populations. We have previously reported that inhalation of real-world mine tailing dusts during lung development can alter lung function and structure in adult male mice. These real-world dusts contain a mixture of metal(loid)s, including arsenic. To determine whether arsenic in inhaled dust plays a role in altering lung development, we exposed C57Bl/6 mice to a background dust (0 arsenic) or to the background dust containing either 3% or 10% by mass, calcium arsenate. Total level of exposure was kept at 100 μg/m3. Calcium arsenate was selected since arsenate is the predominant species found in mine tailings. We found that inhalation exposure during in utero and postnatal lung development led to significant increases in pulmonary baseline resistance, airway hyper-reactivity, and airway collagen and smooth muscle expression in male C57Bl/6 mice. Responses were dependent on the level of calcium arsenate in the simulated dust. These changes were not associated with increased expression of TGF-β1, a marker of epithelial to mesenchymal transition. However, responses were correlated with decreases in the expression of club cell protein 16 (CC16). Dose-dependent decreases in CC16 expression and increases in collagen around airways was seen for animals exposed in utero only (GD), animals exposed postnatally only (PN) and animals continuously exposed throughout development (GDPN). These data suggest that arsenic inhalation during lung development can decrease CC16 expression leading to functional and structural alterations in the adult lung.

Prenatal exposure to arsenic and lung function in children from the New Hampshire Birth Cohort Study

Prenatal arsenic exposure is associated with an increased risk of lung cancer along with multiple non-carcinogenic outcomes, including respiratory diseases in arsenic-contaminated areas. Limited epidemiologic data exist on whether in utero arsenic exposure influences lung development and subsequent respiratory health. We investigated the association between gestational arsenic exposure and childhood lung function in the New Hampshire Birth Cohort Study. Urinary arsenic speciation including inorganic arsenic (iAs), monomethylarsonic acid (MMA), dimethylarsinic acid (DMA) and arsenobetaine was measured in maternal urine samples collected during pregnancy and spirometry was performed in offspring at a median age of 7.4 years. Forced vital capacity (FVC), forced expiratory volume in the first second of exhalation (FEV1), and forced expiratory flow between 25% and 75% of FVC (FEF25-75) standardized z-scores were assessed in linear models as dependent variables with the log2-transformed summation of urinary arsenic species (ΣAs = iAs + MMA + DMA) corrected for specific gravity as an independent variable and with adjustment for maternal smoking status, children's age, sex and height. Among the 358 children in the study, a doubling of ΣAs was associated with a -0.08 (ß) decrease in FVC z-scores (95% confidence interval (CI) from -0.14 to -0.01) and -0.10 (ß) (95% CI from -0.18 to -0.02) decrease in FEV1 z-scores. The inverse association appeared stronger among those mothers with lower secondary methylation index (urinary DMA/MMA), especially among girls. No association was observed for FEF25-75 z-scores. Our results suggest that gestation arsenic exposure at levels relevant to the general US population during the vulnerable period of lung formation may adversely affect lung function in childhood.

Inflammation biomarkers associated with arsenic exposure by drinking water and respiratory outcomes in indigenous children from three Yaqui villages in southern Sonora, México

Environmental arsenic exposure in adults and children has been associated with a reduction in the expression of club cell secretory protein (CC16) and an increase in the expression of matrix metalloproteinase-9 (MMP-9), both biomarkers of lung inflammation and negative respiratory outcomes. The objectives of this study were to determine if the levels of serum CC16 and MMP-9 and subsequent respiratory infections in children are associated with the ingestion of arsenic by drinking water. This cross-sectional study included 216 children from three Yaqui villages, Potam, Vicam, and Cocorit, with levels of arsenic in their ground water of 70.01 ± 21.85, 23.3 ± 9.99, and 11.8 ± 4.42 μg/L respectively. Total arsenic in water and urine samples was determined by inductively coupled plasma/optical emission spectrometry. Serum was analyzed for CC16 and MMP-9 using ELISA. The children had an average urinary arsenic of 79.39 μg/L and 46.8 % had levels above of the national concern value of 50 μg/L. Increased arsenic concentrations in drinking water and average daily arsenic intake by water were associated with decreased serum CC16 levels (β = - 0.12, 95% CI - 0.20, - 0.04 and β = - 0.10, 95% CI - 0.18, - 0.03), and increased serum MMP-9 levels (β = 0.35, 95% CI 0.22, 0.48 and β = 0.29, 95% CI 0.18, 0.40) at significant levels (P < 0.05). However, no association was found between levels of these serum biomarkers and urinary arsenic concentrations. In these children, reduced serum CC16 levels were significantly associated with increased risk of respiratory infections (OR = 0.34, 95% CI 0.13, 0.90). In conclusion, altered levels of serum CC16 and MMP-9 in the children may be due to the toxic effects of arsenic exposure through drinking water.

Arsenic exposure and its joint effects with cigarette smoking and physical exercise on lung function impairment: Evidence from an occupational cohort study

BACKGROUND

Arsenic (As) is an established toxic metal, but its effect on longitudinal lung function change among occupational workers is less conclusive.

METHODS

1243 participants were recruited in a coke-oven plant and followed up from 2010 to 2014. Each individual provided 20 mL morning urine sample at baseline, which was then used for urinary levels of As (U-As) and polycyclic aromatic hydrocarbon (PAH) metabolites detecting. Lung function levels at both baseline and the end of follow-up were determined. Multiple linear regression models were used to analyze the associations between U-As with annual lung function changes, and to evaluate the joint effects of U-As with cigarette smoking and regular physical exercise.

RESULTS

Among all participants, each 2-fold increase in U-As was associated with -12.09 (95%CI: -19.37, -4.81) mL, -0.32% (95%CI: -0.54%, -0.10%), -15.04 (95%CI: -24.62, -5.46) mL, and -0.36% (95%CI: -0.64%, -0.08%) annual changes in reduced forced expiratory volume in 1 second (FEV1), percent predicted FEV1 (ppFEV1), forced vital capacity (FVC), and percent predicted FVC (ppFVC), respectively. These effects were more pronounced among coke-oven workers with smoking (especially heavy smoking with pack-years≥15) and without regular physical exercise. Compared to low-As-exposed (≤4.70 μg/mmol creatinine) non-smokers with regular physical exercise, the high-As-exposed (>4.70 μg/mmol creatinine) smokers without regular physical exercise had the worst annual declines in FEV1 [β (95%CI) = -69.01 (-106.67, -31.34) mL], ppFEV1 [β (95%CI) = -1.94% (-3.02%, -0.87%)], FVC [β (95%CI) = -78.66 (95%CI: -129.46, -27.86) mL], and ppFVC [β (95%CI) = -1.80% (-3.23%, -0.37%)].

CONCLUSIONS

The findings in our prospective cohort study suggested the positively linear dose-response relationship of U-As with annual lung function decline. The adverse effects of As could be enhanced by cigarette smoking and attenuated by regular physical exercise. Specific emphasizes on tobacco control and physical exercise were suggested to prevent As exposure induced pulmonary impairment.

Toxic metal exposure as a possible risk factor for COVID-19 and other respiratory infectious diseases

Multiple medical, lifestyle, and environmental conditions, including smoking and particulate pollution, have been considered as risk factors for COronaVIrus Disease 2019 (COVID-19) susceptibility and severity. Taking into account the high level of toxic metals in both particulate matter (PM2.5) and tobacco smoke, the objective of this review is to discuss recent data on the role of heavy metal exposure in development of respiratory dysfunction, immunotoxicity, and severity of viral diseases in epidemiological and experimental studies, as to demonstrate the potential crossroads between heavy metal exposure and COVID-19 severity risk. The existing data demonstrate that As, Cd, Hg, and Pb exposure is associated with respiratory dysfunction and respiratory diseases (COPD, bronchitis). These observations corroborate laboratory findings on the role of heavy metal exposure in impaired mucociliary clearance, reduced barrier function, airway inflammation, oxidative stress, and apoptosis. The association between heavy metal exposure and severity of viral diseases, including influenza and respiratory syncytial virus has been also demonstrated. The latter may be considered a consequence of adverse effects of metal exposure on adaptive immunity. Therefore, reduction of toxic metal exposure may be considered as a potential tool for reducing susceptibility and severity of viral diseases affecting the respiratory system, including COVID-19.

Low serum indium levels induce expression disorders of some inflammatory factors

OBJECTIVES

It has been reported that occupational exposure to indium compounds, including indium-tin oxide, can induce pulmonary inflammation resulting in serious indium lung disease. However, whether there is an early effect of indium exposure on inflammatory factor expression remains unclear.

METHODS

Twenty indium-tin oxide processing workers and 15 healthy volunteers were recruited to measure serum indium levels, respiratory symptoms, pulmonary function, and serum inflammatory factor levels.

RESULTS

Although low serum indium was detected in workers, lung abnormalities were not increased, compared with healthy population. However, serum G-CSF, IL-4, IL-5, TNF-alpha, and TNF-beta levels were significantly increased, while IL-16 and TIMP-1 were obviously down-regulated in indium-tin oxide processing workers. These inflammatory factor levels showed a significant correlation with serum indium levels.

CONCLUSIONS

Basing on our findings, we speculate that low serum indium levels may induce inflammatory responses, which may be an adaptive response or may cause lung diseases. Therefore, further experiments or follow-up is needed. However, better safeguard procedures and indium exposure reduction should be considered in ITO industry.

Effect of low- and high-level groundwater arsenic on peripheral blood and lung function of exposed rural women

The World Health Organization (WHO) recommended maximum contaminant level (MCL) of arsenic (As) in drinking water at 10 μg/L. Many Asian countries still have their MCL for As at 50 μg/L. The current cross sectional study was conducted on asymptomatic females (without As related skin lesions) selected from rural areas of West Bengal, Baruipur and Dhamakhali [low As 11-50 μg/L; N,93]; Kamardanga & Sibhati [high As>50 μg/L; N,70] and Boria [Control; As<10 μg/L N,118] of West Bengal, India. The study was designed to compare the status of peripheral blood and lung function due to prolonged As exposure. The lung function parameters were considered according to Miller's prediction quadrant - FVC less than 80% indicated restrictive lung, FEV1/FVC less than 70% showed obstructive lung and both FVC and FEV1/FVC less than predicted percentage exhibited combined lung function decrement. The study showed that groundwater As concentration [22.5 ± 19.2 (low), 67.8 ± 26.9 (high) and 1.02 ± 2.3 μg/L (control)] was correlated with nail As content of the enrolled women. Linear regression depicted that nail As content influenced reduction of haemoglobin (β: 0.43; 95%CI: 0.02 to -0.006; p = 0.0001) and CD56⁺ NK cells (β: 0.53; 95%CI: 0.07 to -0.03; p = 0.0001) per 1 μg/g increase in As in nails. Multivariate logistic regression exhibited that nail As content was associated with reduction of lung function parameters [FEV1 (Exp B:1.04; 95%CI: 1.022 to 1.055; p = 0.0001) and FVC (Exp B:1.05; 95%CI: 1.03 to 1.07; p = 0.0001) per 1 μg/g increase in As in nails. Hence the study may be indicative of the fact that even in asymptomatic women, increase in chronic As exposure may weaken immune surveillance and provoke respiratory ailments.

A prospective cohort study of in utero and early childhood arsenic exposure and infectious disease in 4- to 5-year-old Bangladeshi children

Previous research found that infants who were exposed to high levels of arsenic in utero had an increased risk of infectious disease in the first year of life. This prospective study examined the association between arsenic exposures during gestation, and respiratory, diarrheal, and febrile morbidity in children 4–5 years of age.

Health effects of arsenic exposure in Latin America: An overview of the past eight years of research

Studies conducted over the past eight years in Latin America (LA) have continued to produce new knowledge regarding health impacts of arsenic (As) in drinking water. We conducted a systematic review of 92 peer-reviewed English articles published between 2011 and 2018 to expand our understanding on these health effects. Majority of the LA studies on As have been conducted in Chile and Mexico. Additional data have emerged from As-exposed populations in Argentina, Bolivia, Brazil, Colombia, Ecuador, and Uruguay. The present review has documented recent data on the biomarkers of As exposure, genetic susceptibility and genotoxicity, and risk assessment to further characterize the health effects and exposed populations. Some recent findings on the associations of As with bladder and lung cancers, reproductive outcomes, and declined cognitive performance have been consistent with what we reported in our previous systematic review article. We have found highly convincing evidence of in utero As exposure as a significant risk factor for several health outcomes, particularly for bladder cancer, even at moderate level. New data have emerged regarding the associations of As with breast and laryngeal cancers as well as type 2 diabetes. We observed early life As exposure to be associated with kidney injury, carotid intima-media thickness, and various pulmonary outcomes in children. Other childhood effects such as low birth weight, low gestational age, anemia, increased apoptosis, and decreased cognitive functions were also reported. Studies identified genetic variants of As methyltransferase that could determine susceptibility to As related health outcomes. Arsenic-induced DNA damage and alteration of gene and protein expression have also been reported. While the scope of research is still vast, the substantial work done on As exposure and its health effects in LA will help direct further large-scale studies for more comprehensive knowledge and plan appropriate mitigation strategies.

Serum matrix metalloproteinase-9 in children exposed to arsenic from playground dust at elementary schools in Hermosillo, Sonora, Mexico

Arsenic exposure in adults has been associated with increased serum matrix metalloproteinase-9 (MMP-9), a biomarker which is associated with chronic respiratory disease, lung inflammation, cardiovascular disease and cancer. The objective of this study was to evaluate the association between serum MMP-9 levels in children, urinary arsenic, arsenic chronic daily intake (CDI) and arsenic exposure from playground dust. This cross-sectional study examined 127 children from five elementary schools, in Hermosillo, Sonora, Mexico. Arsenic was analyzed in the dust using a portable X-ray fluorescence (XRF) analyzer. Total urinary arsenic was determined by inductively coupled plasma/optical emission spectrometry. Serum was analyzed for MMP-9 using ELISA. Arsenic levels in playground dust averaged 16.9 ± 4.6 mg/kg. Urinary arsenic averaged 34.9 ± 17.1 µg/L. Arsenic concentration in playground dust was positively associated with serum MMP-9 levels in crude analyses and after adjustment (P < 0.01), MMP-9 and CDI were positively associated only after adjustment (P < 0.01), and no association was found between MMP-9 and urinary arsenic. In conclusion, our study showed an association in children between serum MMP-9 levels and playground dust arsenic concentrations. Therefore, exposure to arsenic in dust where children spend significant time may manifest toxic effects.

Exposure to low-dose arsenic in early life alters innate immune function in children

Early-life exposure to arsenic (As) increases risks of respiratory diseases/infections in children. However, data on the ability of the innate immune system to combat bacterial infections in the respiratory tracts of As-exposed children are scarce. To evaluate whether persistent low-dose As exposure alters innate immune function among children younger than 5 years-of-age, mothers and participating children (N = 51) that were members of the Health Effects of Arsenic Longitudinal Study (HEALS) cohort in rural Bangladesh were recruited. Household water As, past and concurrent maternal urinary As (U-As) as well as child U-As were all measured at enrollment. In addition, U-As metabolites were evaluated. Innate immune function was examined via measures of cathelicidin LL-37 in plasma, ex vivo monocyte-derived-macrophage (MDM)-mediated killing of Streptococcus pneumoniae (Spn), and serum bactericidal antibody (SBA) responses against Haemophilus influenzae type b (Hib). Cyto-/chemokines produced by isolated peripheral blood mononuclear cells (PBMC) were assayed using a Multiplex system. Multivariable linear regression analyses revealed that maternal (p < 0.01) and child (p = 0.02) U-As were positively associated with plasma LL-37 levels. Decreased MDM-mediated Spn killing (p = 0.05) and SBA responses (p = 0.02) were seen to be each associated with fractions of mono-methylarsonic acid (MMA; a U-As metabolite) in the children. In addition, U-As levels were seen to be negatively associated with PBMC formation of fractalkine and IL-7, and positively associated with that for IL-13, IL-17 and MIP-1α. These findings suggested that early-life As exposure may disrupt the innate host defense pathway in these children. It is possible that such disruptions may have health consequences later in life.

Low-moderate arsenic exposure and respiratory in American Indian communities in the Strong Heart Study

BACKGROUND

Arsenic exposure through drinking water is an established lung carcinogen. Evidence on non-malignant lung outcomes is less conclusive and suggests arsenic is associated with lower lung function. Studies examining low-moderate arsenic (< 50 μg/L), the level relevant for most populations, are limited. We evaluated the association of arsenic exposure with respiratory health in American Indians from the Northern Plains, the Southern Plains and the Southwest United States, communities with environmental exposure to inorganic arsenic through drinking water.

METHODS

The Strong Heart Study is a prospective study of American Indian adults. This analysis used urinary arsenic measurements at baseline (1989-1991) and spirometry at Visit 2 (1993-1995) from 2132 participants to evaluate associations of arsenic exposure with airflow obstruction, restrictive pattern, self-reported respiratory disease, and symptoms.

RESULTS

Airflow obstruction was present in 21.5% and restrictive pattern was present in 14.4%. The odds ratio (95% confidence interval) for obstruction and restrictive patterns, based on the fixed ratio definition, comparing the 75th to 25th percentile of arsenic, was 1.17 (0.99, 1.38) and 1.27 (1.01, 1.60), respectively, after adjustments, and 1.28 (1.02, 1.60) and 1.33 (0.90, 1.50), respectively, based on the lower limit of normal definition. Arsenic was associated with lower percent predicted FEV1 and FVC, self-reported emphysema and stopping for breath.

CONCLUSION

Low-moderate arsenic exposure was positively associated with restrictive pattern, airflow obstruction, lower lung function, self-reported emphysema and stopping for breath, independent of smoking and other lung disease risk factors. Findings suggest that low-moderate arsenic exposure may contribute to restrictive lung disease.

Urinary arsenic concentration, airway inflammation, and lung function in the U.S. adult population

BACKGROUND

Inorganic arsenic (iAs) is ubiquitous in the environment and has been linked to lung cancer and a number of non-malignant lung disease in both adults and children. However, most studies were conducted in populations with higher arsenic exposure levels in drinking water and relatively little epidemiologic research evaluated the impacts of low levels iAs exposure on non-malignant lung disease among populations that are not primarily exposed to arsenic through drinking water.

OBJECTIVES

We assessed the associations of arsenic exposure with airway inflammation and lung function among U.S. adults aged 20-79 years using data from the National Health and Nutrition Examination Survey 2007-2012 cycles.

METHODS

Two measures of arsenic exposure, urinary total arsenic and dimethylarsonic acid (DMA), were used. We calibrated these two exposure measures by regressing their concentrations by arsenobetaine and extracting the residuals to calculate estimated total arsenic and estimated DMA. Arsenic exposures were modeled as log-transformed continuous variables as well as quartile categories. Fractional exhaled nitric oxide (FENO), an indicator of respiratory inflammation, was available for participants. For lung function, the best forced expiratory volume in the first one second (FEV₁), forced vital capacity (FVC), forced expiratory flow rate (FEF) 25-75%, their percent estimated values, ratios of FEV₁ to FVC, and FEF 25-75% to FVC were used (i.e. FEV₁/FVC and FEF/FVC). Weighted multivariable linear regression models, adjusted for potential confounders, were used to evaluate the association of arsenic exposure with airway inflammation and lung function overall, and among males and females.

RESULTS

Significant associations between arsenic exposure and increased airway inflammation were found. A two-fold increase in urinary total arsenic and DMA was associated with 23.87% (95% CI: 2.66, 49.46) and 14.05% (95% CI: 1.77, 27.81) higher levels of FENO, respectively. In addition, participants in the highest quartile of urinary total arsenic had FENO levels 8.49% (95% CI: 1.13, 16.39) higher than those in the lowest quartile. These associations were similar between males and females. Limited evidence was found for the association with respect to lung function and potential modification effect of sex.

CONCLUSIONS

Arsenic exposure was related to increased risk of airway inflammation but there is limited evidence of an association in relation to lung function. Future research conducted in populations with relatively lower exposure levels that are not primarily exposed to arsenic through drinking water is needed to confirm our findings.

A Meta-analysis of Arsenic Exposure and Lung Function: Is There Evidence of Restrictive or Obstructive Lung Disease?

PURPOSE OF REVIEW

Hundreds of millions of people worldwide are exposed to arsenic via contaminated water. The goal of this study was to identify whether arsenic-associated lung function deficits resemble obstructive- or restrictive-like lung disease, in order to help illuminate a mechanistic pathway and identify at-risk populations.

RECENT FINDINGS

We recently published a qualitative systematic review outlining the body of research on arsenic and non-malignant respiratory outcomes. Evidence from several populations, at different life stages, and at different levels of exposure showed consistent associations of arsenic exposure with chronic lung disease mortality, respiratory symptoms, and lower lung function levels. The published review, however, only conducted a broad qualitative description of the published studies without considering specific spirometry patterns, without conducting a meta-analysis, and without evaluating the dose-response relationship. We searched PubMed and Embase for studies on environmental arsenic exposure and lung function. We performed a meta-analysis using inverse-variance-weighted random effects models to summarize adjusted effect estimates for arsenic and forced expiratory volume in one second (FEV₁), forced vital capacity (FVC), and FEV₁/FVC ratio. Across nine studies, median water arsenic levels ranged from 23 to 860 μg/L. The pooled estimated mean difference (MD) comparing the highest category of arsenic exposure (ranging from > 11 to > 800 μg/L) versus the lowest (ranging from < 10 to < 100 μg/L) for each study for FEV₁ was - 42 mL (95% confidence interval (CI) - 70, - 16) and for FVC was - 50 mL (95% CI - 63, - 37). Three studies reported effect estimates for FEV₁/FVC, for which there was no evidence of an association; the pooled estimated MD was 0.01 (95% CI - 0.005, 0.024). This review supports that arsenic is associated with restrictive impairments based on inverse associations between arsenic and FEV₁ and FVC, but not with FEV₁/FVC. Future studies should confirm whether low-level arsenic exposure is a restrictive lung disease risk factor in order to identify at-risk populations in the USA.

Chronic arsenic exposure in drinking water interferes with the balances of T lymphocyte subpopulations as well as stimulates the functions of dendritic cells in vivo

The immunomodulatory properties of arsenic are nowadays supposed be associated with pathological injuries of this toxicant and the details have not been clarified. Our objective was to explore inflammation, differentiation of diverse T cell subsets, as well as the phenotypic molecules and functions of dendritic cells (DCs) by chronic arsenic exposure in vivo. We exposed different concentrations of arsenic (0, 0.1, 1 and 10 mg/L) in drinking water for 6 and 12 months in C57BL/6 mice. We first confirmed that low levels of arsenic induced excess inflammation evidenced by accumulation of macrophages and lymphocytes in bronchoalveolar lavage fluid (BALF), secretion of pro-inflammatory cytokine IL-1β in BALF and serum, as well as histological analysis. Flow cytometry analysis revealed that arsenic disturbed CD4/CD8 T-cell ratio in isolated pneumonocytes and splenocytes, as well as enhanced IFN-γ and reduced IL-4 in spleen. The mRNA expressions of transcription factors (T-bet, GATA3, ROR-γt) and cytokines (IFN-γ, IL-4, IL-10, IL-23, IL-22) showed the imbalanced Th1/Th2/Th17 differentiation in arsenic exposed lung and spleen. We further testified that arsenic enhanced the percentages of CD11c⁺ DCs, and promoted the expressions of antigen presentation molecule MHC II and cytokine IL-12, co-stimulatory molecules (CD86, CD80), and chemokine receptors (CCR7, CCR5) in vivo. Moreover, arsenic activated the expressions of immune-related MAPKs and NF-κB. Taken together, our study here demonstrated that chronic arsenic exposure could disrupt the immune homeostasis in vivo possibly by interfering with the differentiation of Th1/Th2/Th17 subsets as well as the function of DCs.

Early life inhalation exposure to mine tailings dust affects lung development

Exposure to mine tailings dust from active and abandoned mining operations may be a very significant health hazard, especially to sensitive populations living in arid and semi-arid climates like the desert southwest of the US. It is anticipated that early life exposures during sensitive times of development can lead to adult disease. However, very few studies have investigated the effects of inhalation exposure to real world dusts during lung development. Using a mouse model, we have examined the effect(s) of inhalation of real world mine tailing dusts under three separate conditions: (1) Exposure only during in utero development (exposure of the pregnant moms) (2) exposure only after birth and (3) exposures that occurred continuously during in utero development, through gestation and birth until the mice reached adulthood (28 days old). We found that the most significant changes in lung structure and function were observed in male mice when exposure occurred continuously throughout development. These changes included increased airway hyper-reactivity, increased expression of epithelial to mesenchymal (EMT) transition protein markers and increased expression of cytokines related to eosinophils. The data also indicate that in utero exposures through maternal inhalation can prime the lung of male mice for more severe responses to subsequent postnatal exposures. This may be due to epigenetic alterations in gene regulation, immune response, molecular signaling, and growth factors involved in lung development that may make the neonatal lung more susceptible to continued dust exposure.

Impact of prenatal arsenic exposure on chronic adult diseases

Exposure to environmental stressors during susceptible windows of development can result in negative health outcomes later in life, a concept known as the Developmental Origins of Health and Disease (DOHaD). There is a growing body of evidence that exposures to metals early in life (in utero and postnatal) increase the risk of developing adult diseases such as cancer, cardiovascular disease, non-alcoholic fatty liver disease, and diabetes. Of particular concern is exposure to the metalloid arsenic, a drinking water contaminant and worldwide health concern. Epidemiological studies of areas with high levels of arsenic in the drinking water, such as some regions in Chile and Bangladesh, indicate an association between in utero arsenic exposure and the development of adult diseases. Therefore, the need for experimental models to address the mechanism underlining early onset of adult diseases have emerged including the in utero and whole-life exposure models. This review will highlight the epidemiological events and subsequent novel experimental models implemented to study the impact of early life exposure to arsenic on the development of adult diseases. In addition, current research using these models will be discussed as well as possible underlying mechanism for the early onset of disease. Abbreviations: ALT: alanine aminotransferase; AMI: acute myocardial infarction; AST: aspartate aminotransferase; ATSDR: Agency for Toxic Substances and Disease Registry; CVD: cardiovascular disease; DMA: dimethylarsinate; DOHaD: Developmental Origins of Health and Disease; EPA: U.S. Environmental Protection Agency; ER-α: estrogen receptor alpha; HDL: high-density lipoprotein; HOMA-IR: homeostatic model assessment of insulin resistance; iAs: inorganic arsenic; LDL: low-density lipoprotein; MetS: metabolic syndrome; MMA: monomethylarsonate; NAFLD: non-alcoholic fatty liver disease; PND: postnatal day; ppb: parts per billion; ppm: parts per million; SAM: S-adenosylmethionine; USFDA: United States Food and Drug Administration.

Potential Co-exposure to Arsenic and Fluoride and Biomonitoring Equivalents for Mexican Children

BACKGROUND

Mexico is included in the list of countries with concurrent arsenic and fluoride contamination in drinking water. Most of the studies have been carried out in the adult population and very few in the child population. Urinary arsenic and urinary fluoride levels have been accepted as good biomarkers of exposure dose. The Biomonitoring Equivalents (BE) values are useful tools for health assessment using human biomonitoring data in relation to the exposure guidance values, but BE information for children is limited.

METHODS

We conducted a systematic review of the reported levels of arsenic and fluoride in drinking water, urinary quantification of speciated arsenic (inorganic arsenic and its methylated metabolites), and urinary fluoride levels in child populations. For BE values, urinary arsenic and fluoride concentrations reported in Mexican child populations were revised discussing the influence of factors such as diet, use of dental products, sex, and metabolism.

RESULTS

Approximately 0.5 and 6 million Mexican children up to 14 years of age drink water with arsenic levels over 10 μg/L and fluoride over 1.5 mg/L, respectively. Moreover, 40% of localities with arsenic levels higher than 10 μg/L also present concurrent fluoride exposure higher than 1.5 mgF/L. BE values based in urinary arsenic of 15 μg/L and urinary fluoride of 1.2 mg/L for the environmentally exposed child population are suggested.

CONCLUSIONS

An actual risk map of Mexican children exposed to high levels of arsenic, fluoride, and both arsenic and fluoride in drinking water was generated. Mexican normativity for maximum contaminant level for arsenic and fluoride in drinking water should be adjusted and enforced to preserve health. BE should be used in child populations to investigate exposure.

Ellagic acid: A promising protective remedy against testicular toxicity induced by arsenic

Chronic exposure to arsenic, an inducer of oxidative stress, is one of the major causes of male infertility. Therefore, the present study investigated the protective role of Ellagic acid (EA), as a natural antioxidant, against testicular toxicity evoked by arsenic. Thirty-five male Wistar rats were divided into 5 treatment groups. Group 1 served as control, group 2 were orally exposed to sodium arsenite (SA, 10 mg/kg; 21 days), groups 3 and 4 were initially exposed to SA for 7 days and then were treated with both EA (10 and 30 mg/kg) and SA up to 21 days, and group 5 was treated with EA for 14 days. After this period, biochemical and histopathological parameters were evaluated in serum samples and testicular tissue. SA markedly reduced levels of serum testosterone, total antioxidant capacity, reduced glutathione as well as the activity of antioxidant enzymes. Furthermore, SA enhanced levels of malondialdehyde, tumor necrosis factor-α, interleukin-1β and nitric oxide in testes. Treatment with EA was found to reduce testicular arsenic accumulation and oxidative stress parameters. In addition, EA improved the serum testosterone level, testicular antioxidant markers and histological parameters after exposure to SA. EA may emerge as a promising therapeutic option to protect testes from arsenic-induced toxicity through reducing oxidative stress and inflammatory responses.

Subchronic Arsenism Disorders mRNA Expression of Cytokines and Immunoglobulins in the Intestinal Tract of the Cock

Provision of feed containing arsenic may cause intestinal flora imbalance and consequently, the dysfunction of immunological protection of the cock. To understand the intricate tuning of immune responses in the intestinal tract elicited by subchronic arsenism, a cock model (1-day-old Hy-line cocks) was established by subjecting cocks to different environmentally relevant concentrations of arsenic in the diet for 90 days. Intestinal cytokine and immunoglobulin (Ig) messenger RNA (mRNA) expression levels were determined using real-time PCR on days 30, 60, and 90. Results showed that, compared to those of the control groups, the mRNA levels of interleukin (IL)-1β, IL-2, IL-4, and interferon (IFN)-γ displayed increases on day 30 then decreases on days 60 and 90 dose-dependently in every tissue. Except for the decrease in the jejunum, the mRNA levels of IL-6 and IL-8 were increased in the duodenum, ileum, cecum, and rectum. However, the mRNA levels of IL-12β decreased in every tissue and every time point compared to those of the control groups. In contrast, chicks showed considerably higher expression levels of IgA, IgM, and IgG after exposure to arsenic. These results demonstrated that immune strategies of cocks were disturbed when suffered from subchronic arsenism, at least on the intestinal level.

Dose and Diet - Sources of Arsenic Intake in Mouse in Utero Exposure Scenarios

In humans, early life exposure to inorganic arsenic is associated with adverse health effects. Inorganic arsenic in utero or in early postnatal life also produces adverse health effects in offspring of pregnant mice that consumed drinking water containing low part per billion levels of inorganic arsenic. Because aggregate exposure of pregnant mice to inorganic arsenic from both drinking water and food has not been fully evaluated in experimental studies, quantifying arsenic exposure of the developing mouse is problematic. Here, we determined levels of total arsenic and arsenic species in natural ingredient rodent diets that are composed of many plant and animal-derived foodstuffs and in a purified ingredient rodent diet that is composed of a more restricted mixture of foodstuffs. In natural ingredient diets, total arsenic levels ranged from ∼60 to ∼400 parts per billion, and in the purified ingredient diet, total arsenic level was 13 parts per billion. Inorganic arsenic was the predominant arsenic species in trifluoroacetic acid extracts of each diet. Various exposure scenarios were evaluated using information on inorganic arsenic levels in diet and drinking water and on daily food and water consumption of pregnant mice. In a scenario in which pregnant mice consumed drinking water with 10 parts per billion of inorganic arsenic and a natural ingredient diet containing 89 parts per billion of inorganic arsenic, drinking water contributed only ∼20% of inorganic arsenic intake. Quantitation of arsenic species in diets used in studies in which drinking water is the nominal source of arsenic exposure provides more accurate dosimetry and improves understanding of dose-response relations. Use of purified ingredient diets will minimize the discrepancy between the target dosage level and the actual dosage level attained in utero exposure studies designed to evaluate effects of low level exposure to inorganic arsenic.

Imbalanced immune responses involving inflammatory molecules and immune-related pathways in the lung of acute and subchronic arsenic-exposed mice

Inorganic arsenic has been claimed to increase the risk of pulmonary diseases through ingestion, as opposed to inhalation, which makes it a unique and intriguing environmental toxicant. However, the immunotoxic effects of lung, one of the targets of arsenic exposure, have not been extensively investigated in vivo. In the present study, we first confirmed that 2.5, 5 and 10mg/kg NaAsO₂ orally for 24h dose-dependently triggered the infiltration of neutrophils, lymphocytes and macrophages in BALF. Not only the transcription activity, but also the secretion of proinflammatory cytokines IL-1β, IL-6 and TNF-α were consistently raised in the lung and BALF of acute arsenic-exposed mice. Acute oral administration of NaAsO₂ also raised pulmonary MPO activity and mRNA levels of chemokine Mip-2 and Mcp-1. Meanwhile, obvious histopathological damages with inflammatory cells infiltration and erythrocyte aggregation around the capillaries were verified in the lung of mice drank arsenic-rich water freely for 3 months. Furthermore, we affirmed notable disturbance of CD4⁺ T-cell differentiation in the lung of acute arsenic-exposed mice, as demonstrated by up-regulated mRNA levels of regulator Gata3 and cytokine Il-4 of Th2, enhanced Foxp3 and Il-10 of Treg, down-regulated T-bet and Ifn-γ of Th1, as well as lessened Ror-γt and Il-23 of Th17. However, impressive elevation of cytokine Ifn-γ and Il-23, as well as moderate enhancement of Il-4 and Il-10 were found in the lung by subchronic arsenic administration. Finally, our present study demonstrated that both a single and sustained arsenic exposure prominently increased the expression of immune-related p38, JNK, ERK1/2 and NF-κB proteins in the lung tissue. While disrupting the pulmonary redox homeostasis by increasing MDA levels, exhausting GSH and impaired enzyme activities of CAT and GSH-Px, antioxidant regulator NRF2 and its downstream targets HO-1 and GSTO1/2 were also up-regulated by both acute and subchronic arsenic treatment. Conclusively, our present study demonstrated both acute and subchronic oral administration of arsenic triggers multiple pulmonary immune responses involving inflammatory molecules and T-cell differentiation, which might be closely associated with the imbalanced redox status and activation of immune-related MAPKs, NF-κB and anti-inflammatory NRF2 pathways.

Effects of Orally Ingested Arsenic on Respiratory Epithelial Permeability to Bacteria and Small Molecules in Mice

BACKGROUND

Arsenic exposure via drinking water impacts millions of people worldwide. Although arsenic has been associated epidemiologically with increased lung infections, the identity of the lung cell types targeted by peroral arsenic and the associated immune mechanisms remain poorly defined.

OBJECTIVES

We aimed to determine the impact of peroral arsenic on pulmonary antibacterial host defense.

METHODS

Female C57BL/6 mice were administered drinking water with 0, 250 ppb, or 25 ppm sodium arsenite for 5 wk and then challenged intratracheally with Klebsiella pneumoniae, Streptococcus pneumoniae, or lipopolysaccharide. Bacterial clearance and immune responses were profiled.

RESULTS

Arsenic had no effect on bacterial clearance in the lung or on the intrapulmonary innate immune response to bacteria or lipopolysaccharide, as assessed by neutrophil recruitment to, and cytokine induction in, the airspace. Alveolar macrophage TNFα production was unaltered. By contrast, arsenic-exposed mice had significantly reduced plasma TNFα in response to systemic lipopolysaccharide challenge, together suggesting that the local airway innate immune response may be relatively preserved from arsenic intoxication. Despite intact intrapulmonary bacterial clearance during pneumonia, arsenic-exposed mice suffered dramatically increased bacterial dissemination to the bloodstream. Mechanistically, this was linked to increased respiratory epithelial permeability, as revealed by intratracheal FITC-dextran tracking, serum Club Cell protein 16 measurement, and other approaches. Consistent with barrier disruption at the alveolar level, arsenic-exposed mice had evidence for alveolar epithelial type 1 cell injury.

CONCLUSIONS

Peroral arsenic has little effect on local airway immune responses to bacteria but compromises respiratory epithelial barrier integrity, increasing systemic translocation of inhaled pathogens and small molecules. https://doi.org/10.1289/EHP1878.

Decreased lung function with mediation of blood parameters linked to e-waste lead and cadmium exposure in preschool children

Blood lead (Pb) and cadmium (Cd) levels have been associated with lower lung function in adults and smokers, but whether this also holds for children from electronic waste (e-waste) recycling areas is still unknown. To investigate the contribution of blood heavy metals and lung function levels, and the relationship among living area, the blood parameter levels, and the lung function levels, a total of 206 preschool children from Guiyu (exposed area), and Haojiang and Xiashan (reference areas) were recruited and required to undergo blood tests and lung function tests during the study period. Preschool children living in e-waste exposed areas were found to have a 1.37 μg/dL increase in blood Pb, 1.18 μg/L increase in blood Cd, and a 41.00 × 10⁹/L increase in platelet counts, while having a 2.82 g/L decrease in hemoglobin, 92 mL decrease in FVC and 86 mL decrease in FEV₁. Each unit of hemoglobin (1 g/L) decline was associated with 5 mL decrease in FVC and 4 mL decrease in FEV₁. We conclude that children living in e-waste exposed area have higher levels of blood Pb, Cd and platelets, and lower levels of hemoglobin and lung function. Hemoglobin can be a good predictor for lung function levels.

Arsenic alters transcriptional responses to Pseudomonas aeruginosa infection and decreases antimicrobial defense of human airway epithelial cells

Arsenic contamination of drinking water and food threatens the health of hundreds of millions of people worldwide by increasing the risk of numerous diseases. Arsenic exposure has been associated with infectious lung disease in epidemiological studies, but it is not yet understood how ingestion of low levels of arsenic increases susceptibility to bacterial infection. Accordingly, the goal of this study was to examine the effect of arsenic on gene expression in primary human bronchial epithelial (HBE) cells and to determine if arsenic altered epithelial cell responses to Pseudomonas aeruginosa, an opportunistic pathogen. Bronchial epithelial cells line the airway surface, providing a physical barrier and serving critical roles in antimicrobial defense and signaling to professional immune cells. We used RNA-seq to define the transcriptional response of HBE cells to Pseudomonas aeruginosa, and investigated how arsenic affected HBE gene networks in the presence and absence of the bacterial challenge. Environmentally relevant levels of arsenic significantly changed the expression of genes involved in cellular redox homeostasis and host defense to bacterial infection, and decreased genes that code for secreted antimicrobial factors such as lysozyme. Using pathway analysis, we identified Sox4 and Nrf2-regulated gene networks that are predicted to mediate the arsenic-induced decrease in lysozyme secretion. In addition, we demonstrated that arsenic decreased lysozyme in the airway surface liquid, resulting in reduced lysis of Microccocus luteus. Thus, arsenic alters the expression of genes and proteins in innate host defense pathways, thereby decreasing the ability of the lung epithelium to fight bacterial infection.

Chronic early childhood exposure to arsenic is associated with a TNF-mediated proteomic signaling response

Exposure to inorganic arsenic (iAs) in drinking water is a global public health concern and is associated with a range of health outcomes, including immune dysfunction. Children are a particularly sensitive population to the effects of inorganic arsenic, yet the biological mechanisms underlying adverse health outcomes are understudied. Here we used a proteomic approach to examine the effects of iAs exposure on circulating serum protein levels in a cross-sectional children's cohort in Mexico. To identify iAs-associated proteins, levels of total urinary arsenic (U-tAs) and its metabolites were determined and serum proteins assessed for differences in expression. The results indicate an enrichment of Tumor Necrosis Factor-(TNF)-regulated immune and inflammatory response proteins that displayed decreased expression levels in relation to increasing U-tAs. Notably, when analyzed in the context of the proportions of urinary arsenic metabolites in children, the most robust response was observed in relation to the monomethylated arsenicals. This study is among the first serum proteomics assessment in children exposed to iAs.

DNA methylation of extracellular matrix remodeling genes in children exposed to arsenic

Several novel mechanistic findings regarding to arsenic's pathogenesis has been reported and some of them suggest that the etiology of some arsenic induced diseases are due in part to heritable changes to the genome via epigenetic processes such as DNA methylation, histone maintenance, and mRNA expression. Recently, we reported that arsenic exposure during in utero and early life was associated with impairment in the lung function and abnormal receptor for advanced glycation endproducts (RAGE), matrix metalloproteinase-9 (MMP-9) and tissue inhibitor of matrix metalloproteinase-1 (TIMP-1) sputum levels. Based on our results and the reported arsenic impacts on DNA methylation, we designed this study in our cohort of children exposed in utero and early childhood to arsenic with the aim to associate DNA methylation of MMP9, TIMP1 and RAGE genes with its protein sputum levels and with urinary and toenail arsenic levels. The results disclosed hypermethylation in MMP9 promotor region in the most exposed children; and an increase in the RAGE sputum levels among children with the mid methylation level; there were also positive associations between MMP9 DNA methylation with arsenic toenail concentrations; RAGE DNA methylation with iAs, and %DMA; and finally between TIMP1 DNA methylation with the first arsenic methylation. A negative correlation between MMP9 sputum levels with its DNA methylation was registered. In conclusion, arsenic levels were positive associated with the DNA methylation of extracellular matrix remodeling genes;, which in turn could modifies the biological process in which they are involved causing or predisposing to lung diseases.

Biological effects and epidemiological consequences of arsenic exposure, and reagents that can ameliorate arsenic damage in vivo

Through contaminated diet, water, and other forms of environmental exposure, arsenic affects human health. There are many U.S. and worldwide "hot spots" where the arsenic level in public water exceeds the maximum exposure limit. The biological effects of chronic arsenic exposure include generation of reactive oxygen species (ROS), leading to oxidative stress and DNA damage, epigenetic DNA modification, induction of genomic instability, and inflammation and immunomodulation, all of which can initiate carcinogenesis. High arsenic exposure is epidemiologically associated with skin, lung, bladder, liver, kidney and pancreatic cancer, and cardiovascular, neuronal, and other diseases. This review briefly summarizes the biological effects of arsenic exposure and epidemiological cancer studies worldwide, and provides an overview for emerging rodent-based studies of reagents that can ameliorate the effects of arsenic exposure in vivo. These reagents may be translated to human populations for disease prevention. We propose the importance of developing a biomarker-based precision prevention approach for the health issues associated with arsenic exposure that affects millions of people worldwide.

Cognitive performance among cohorts of children exposed to a waste disposal site containing heavy metals in Chile

Between 1984 and 1998, people living in Arica were involuntarily exposed to metal-containing waste stored in the urban area. The study aims to determine whether children who lived near the waste disposal site during early childhood experienced negative effects on their cognitive development. The cognitive performance was assessed using the Wechsler Intelligence Scale for Children. The exposure variable was defined by the year of birth in three categories: (1) Pre-remediation (born before 1999); (2) During-remediation (born between 1999 and 2003); and (3) Post-remediation (born after 2003). In the crude analysis, a difference of 10 points in the IQ average was observed between the group born in the pre- (81.9 points) and post-remediation period (91.1 points). The difference between both groups was five times higher as compared to children of similar age and socioeconomic status in other cities of Chile. This result could be related with a period of high potential for exposure to this contaminated site.

High risks of lung disease associated with early-life and moderate lifetime arsenic exposure in northern Chile

BACKGROUND

Arsenic in drinking water has been associated with increases in lung disease, but information on the long-term impacts of early-life exposure or moderate exposure levels are limited.

METHODS

We investigated pulmonary disease and lung function in 795 subjects from three socio-demographically similar areas in northern Chile: Antofagasta, which had a well-described period of high arsenic water concentrations (860μg/L) from 1958 to 1970; Iquique, which had long-term arsenic water concentrations near 60μg/L; and Arica, with long-term water concentrations ≤10μg/L.

RESULTS

Compared to adults never exposed >10μg/L, adults born in Antofagasta during the high exposure period had elevated odds ratios (OR) of respiratory symptoms (e.g., OR for shortness of breath=5.56, 90% confidence interval (CI): 2.68-11.5), and decreases in pulmonary function (e.g., 224mL decrease in forced vital capacity in nonsmokers, 90% CI: 97-351mL). Subjects with long-term exposure to arsenic water concentrations near 60μg/L also had increases in some pulmonary symptoms and reduced lung function.

CONCLUSIONS

Overall, these findings provide new evidence that in utero or childhood arsenic exposure is associated with non-malignant pulmonary disease in adults. They also provide preliminary new evidence that long-term exposures to moderate levels of arsenic may be associated with lung toxicity, although the magnitude of these latter findings were greater than expected and should be confirmed.

DNA methylation changes in Mexican children exposed to arsenic from two historic mining areas in San Luis potosí

Arsenic is a carcinogen and epimutagen that threatens the health of exposed populations worldwide. In this study, we examined the methylation status of Alu and long interspersed nucleotide elements (LINE-1) and their association with levels of urinary arsenic in 84 Mexican children between 6 and 12 years old from two historic mining areas in the State of San Luis Potosí, Mexico. Urinary arsenic levels were determined by atomic absorption spectrophotometry and DNA methylation analysis was performed in peripheral blood leukocytes by bisulfite-pyrosequencing. The geometric mean of urinary arsenic was 26.44 µg/g Cr (range 1.93-139.35). No significant differences in urinary arsenic or methylation patterns due to gender were observed. A positive correlation was found between urinary arsenic and the mean percentage of methylated cytosines in Alu sequences (Spearman correlation coefficient r = 0.532, P < 0.001), and a trend of LINE-1 hypomethylation was also observed (Spearman correlation coefficient r = -0.232, P = 0.038) after adjustment for sex and age. A linear regression model showed an association with log-normalized urinary arsenic for Alu (β = 1.05, 95% CI: 0.67; 1.43, P < 0.001) and LINE-1 (β = -0.703, 95% CI: -1.36; -0.38, P = 0.038). Despite the low-level arsenic exposure, a subtle epigenetic imbalance measured as DNA methylation was detected in the leukocytes of Mexican children living in two historic mining areas. Environ. Mol. Mutagen. 57:717-723, 2016. © 2016 Wiley Periodicals, Inc.

Association between polymorphisms in arsenic metabolism genes and urinary arsenic methylation profiles in girls and boys chronically exposed to arsenic

Disease manifestations or susceptibilities often differ among individuals exposed to the same concentrations of arsenic (As). These differences have been associated with several factors including As metabolism, sex, age, genetic variants, nutritional status, smoking, and others. This study evaluated the associations between four As metabolism-related gene polymorphisms/null genotypes with urinary As methylation profiles in girls and boys chronically exposed to As. In a total of 332 children aged 6-12 years, the frequency of AS3MT, GSTO1, GSTT1, and GSTM1 polymorphisms/null genotypes and As urinary metabolites were measured. The results revealed that total As and monomethyl metabolites of As (MMA) levels were higher in boys than in girls. No differences in the frequency of the evaluated polymorphisms were found between girls and boys. In AS3MT-Met287Thr carriers, %MMA levels were higher and second methylation levels (defined as dimethylarsinic acid divided by MMA) were lower. In children with the GSTM1 null genotype, second methylation levels were higher. In boys, a positive association between the AS3MT-Met287Thr polymorphism with %MMA and between the GSTO1-Glu155del and As(v) was found; whereas, a negative relationship was identified between AS3MT-Met287Thr and second methylation profiles. In girls, a positive association was found between the GSTO1-Ala140Asp polymorphism with second methylation levels. In conclusion, our data indicate that gender, high As exposure levels, and polymorphisms in the evaluated genes negatively influenced As metabolism. Environ. Mol. Mutagen. 57:516-525, 2016. © 2016 Wiley Periodicals, Inc.

Inorganic arsenic and respiratory health, from early life exposure to sex-specific effects: A systematic review

This systematic review synthesizes the diverse body of epidemiologic research accrued on inorganic arsenic exposure and respiratory health effects. Twenty-nine articles were identified that examined the relationship between inorganic arsenic exposure and respiratory outcomes (i.e. lung function, symptoms, acute respiratory infections, chronic non-malignant lung diseases, and non-malignant lung disease mortality). There was strong evidence of a general association between arsenic and non-malignant respiratory illness, including consistent evidence on lung function impairment, acute respiratory tract infections, respiratory symptoms, and non-malignant lung disease mortality. Overall, early life exposure (i.e. in utero and/or early-childhood) had a marked effect throughout the lifespan. This review also identified some research gaps, including limited evidence at lower levels of exposure (water arsenic <100μg/L), mixed evidence of sex differences, and some uncertainty on arsenic and any single non-malignant respiratory disease or pathological process. Common limitations, including potential publication bias; non-comparability of outcome measures across included articles; incomplete exposure histories; and limited confounder control attenuated the cumulative strength of the evidence as it relates to US populations. This systematic review provides a comprehensive assessment of the epidemiologic evidence and should be used to guide future research on arsenic's detrimental effects on respiratory health.