Chronic respiratory symptoms in children following in utero and early life exposure to arsenic in drinking water in Bangladesh

Prenatal Origins of Obstructive Airway Disease: Starting on the Wrong Trajectory?

From the results of well-performed population health studies, we now have excellent data demonstrating that deficits in adult lung function may be present early in life, possibly as a result of developmental disorders, incurring a lifelong risk of obstructive airway diseases such as asthma and chronic obstructive pulmonary disease. Suboptimal fetal development results in intrauterine growth restriction and low birth weight at term (an outcome distinct from preterm complications), which are associated with subsequent obstructive disease. Numerous prenatal exposures and disorders compromise fetal development and these are summarized herein. Various physiological, structural, and mechanical abnormalities may result from prenatal disruption, including changes to airway smooth muscle structure-function, goblet cell biology, airway stiffness, geometry of the bronchial tree, lung parenchymal structure and mechanics, respiratory skeletal muscle contraction, and pulmonary inflammation. The literature therefore supports the need for early life intervention to prevent or correct growth defects, which may include simple nutritional or antioxidant therapy. © 2024 American Physiological Society. Compr Physiol 14:5729-5762, 2024.

Associations between prenatal metal and metalloid mixtures in teeth and reductions in childhood lung function

BACKGROUND

Metal(oid)s have been cross-sectionally associated with lung function outcomes in childhood but there is limited data on their combined effects starting in utero. Child sex may further modify these effects.

OBJECTIVE

Examine associations between in utero and early life exposure to metals assessed via novel dentine biomarkers and childhood lung function and explore effect modification by child sex.

METHODS

Analyses included 291 children enrolled in the Programming Research in Obesity, Growth, Environment and Social Stressors (PROGRESS) study, a longitudinal birth cohort study in Mexico City. Weekly dentine levels of arsenic (As), cadmium (Cd), cobalt (Co), copper (Cu), manganese (Mn), nickel (Ni), and lead (Pb) were measured from 15 weeks pre-birth to 15 weeks post birth in deciduous children's teeth. Lung function was tested at ages 8-14 years and then modeled as age, height and sex adjusted z-scores. Associations were modeled using lagged weighted quantile sum (LWQS) regression to evaluate the potential for a time-varying mixture effect adjusting for maternal age and education at enrollment and exposure to environmental tobacco smoke in pregnancy. Models were also stratified by sex.

RESULTS

We identified a window of susceptibility at 12-15 weeks pre-birth in which the metal mixture was associated with lower FVC z-scores in children aged 8-14 years. Cd and Mn were the largest contributors to the mixture effect (70 %). There was also some evidence of effect modification by sex, in which the mean weights and weighted correlations over the identified window was more evident in males when compared to females. In the male stratum, Cd, Mn and additionally Pb also dominated the mixture association.

CONCLUSIONS

Prenatal metal(oid) exposure was associated with lower lung function in childhood. These findings underscore the need to consider both mixtures and windows of susceptibility to fully elucidate effects of prenatal metal(oid) exposure on childhood lung function.

Toxic metals and pediatric clinical immune dysfunction: A systematic review of the epidemiological evidence

BACKGROUND

Children are at high risk for exposure to toxic metals and are vulnerable to their effects. Significant research has been conducted evaluating the role of these metals on immune dysfunction, characterized by biologic and clinical outcomes. However, there are inconsistencies in these studies. The objective of the present review is to critically evaluate the existing literature on the association between toxic metals (lead, mercury, arsenic, and cadmium) and pediatric immune dysfunction.

METHODS

Seven databases (PubMed (NLM), Embase (Elsevier), CINAHL (Ebsco), Web of Science (Clarivate Analytics), ProQuest Public Health Database, and ProQuest Environmental Science Collection) were searched following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines in February 2024. Rayaan software identified duplicates and screened by title and abstract in a blinded and independent review process. The remaining full texts were reviewed for content and summarized. Exclusions during the title, abstract, and full-text reviews included: 1) not original research, 2) not epidemiology, 3) did not include toxic metals, 4) did not examine an immune health outcome, or 5) not pediatric (>18 years). This systematic review protocol followed the PRISMA guidelines. Rayaan was used to screen records using title and abstract by two blinded and independent reviewers. This process was repeated for full-text article screening selection.

RESULTS

The search criteria produced 7906 search results; 2456 duplicate articles were removed across search engines. In the final review, 79 studies were included which evaluated the association between toxic metals and outcomes indicative of pediatric immune dysregulation.

CONCLUSIONS

The existing literature suggests an association between toxic metals and pediatric immune dysregulation. Given the imminent threat of infectious diseases demonstrated by the recent COVID-19 epidemic in addition to increases in allergic disease, understanding how ubiquitous exposure to these metals in early life can impact immune response, infection risk, and vaccine response is imperative.

Drinking Water From Private Wells and Risks to Children

Drinking water for approximately 23 million US households is obtained from private wells. These wells can become contaminated by pollutant chemicals or pathogenic organisms, leading to significant illness. Although the US Environmental Protection Agency and all states offer guidance for construction, maintenance, and testing of private wells, most states only regulate the construction of new private water wells. With a few exceptions, there is little regulation after construction. Well owners are responsible for their own wells. Children may also drink well water at child care or when traveling. Illness resulting from children’s ingestion of contaminated water can be severe. This report reviews relevant aspects of groundwater and wells; describes the common chemical and microbiologic contaminants; gives an algorithm with recommendations for inspection, testing, and remediation for wells providing drinking water for children; and provides references and Internet resources for more information.

The Pregnancy, Arsenic, and Immune Response (PAIR) Study in rural northern Bangladesh

BACKGROUND

Arsenic exposure and micronutrient deficiencies may alter immune reactivity to influenza vaccination in pregnant women, transplacental transfer of maternal antibodies to the foetus, and maternal and infant acute morbidity.

OBJECTIVES

The Pregnancy, Arsenic, and Immune Response (PAIR) Study was designed to assess whether arsenic exposure and micronutrient deficiencies alter maternal and newborn immunity and acute morbidity following maternal seasonal influenza vaccination during pregnancy.

POPULATION

The PAIR Study recruited pregnant women across a large rural study area in Gaibandha District, northern Bangladesh, 2018-2019.

DESIGN

Prospective, longitudinal pregnancy and birth cohort.

METHODS

We conducted home visits to enrol pregnant women in the late first or early second trimester (11-17 weeks of gestational age). Women received a quadrivalent seasonal inactivated influenza vaccine at enrolment. Follow-up included up to 13 visits between enrolment and 3 months postpartum. Arsenic was measured in drinking water and maternal urine. Micronutrient deficiencies were assessed using plasma biomarkers. Vaccine-specific antibody titres were measured in maternal and infant serum. Weekly telephone surveillance ascertained acute morbidity symptoms in women and infants.

PRELIMINARY RESULTS

We enrolled 784 pregnant women between October 2018 and March 2019. Of 784 women who enrolled, 736 (93.9%) delivered live births and 551 (70.3%) completed follow-up visits to 3 months postpartum. Arsenic was detected (≥0.02 μg/L) in 99.7% of water specimens collected from participants at enrolment. The medians (interquartile ranges) of water and urinary arsenic at enrolment were 5.1 (0.5, 25.1) μg/L and 33.1 (19.6, 56.5) μg/L, respectively. Water and urinary arsenic were strongly correlated (Spearman's ⍴ = 0.72) among women with water arsenic ≥ median but weakly correlated (⍴ = 0.17) among women with water arsenic < median.

CONCLUSIONS

The PAIR Study is well positioned to examine the effects of low-moderate arsenic exposure and micronutrient deficiencies on immune outcomes in women and infants.

REGISTRATION

NCT03930017.

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.

Human adaptation to arsenic in Bolivians living in the Andes

Humans living in the Andes Mountains have been historically exposed to arsenic from natural sources, including drinking water. Enzymatic methylation of arsenic allows it to be excreted more efficiently by the human body. Adaptation to high-arsenic environments via enhanced methylation and excretion of arsenic was first reported in indigenous women in the Argentinean Andes, but whether adaptation to arsenic is a general phenomenon across native populations from the Andes Mountains remains unclear. Therefore, we evaluated whether adaptation to arsenic has occurred in the Bolivian Andes by studying indigenous groups who belong to the Aymara-Quechua and Uru ethnicities and have lived in the Bolivian Andes for generations. Our population genetics methods, including genome-wide selection scans based on linkage disequilibrium patterns and allele frequency differences, in combination with targeted and whole-genome sequencing and genotype-phenotype association analyses, detected signatures of positive selection near the gene encoding arsenite methyltransferase (AS3MT), the main arsenic methylating enzyme. This was among the strongest selection signals (top 0.5% signals via locus-specific branch length and extended haplotype homozygosity tests) at a genome-wide level in the Bolivian study groups. We found a large haplotype block of 676 kb in the AS3MT region and identified candidate functional variants for further analysis. Moreover, our analyses revealed associations between AS3MT variants and the fraction of mono-methylated arsenic in urine and showed that the Bolivian study groups had the highest frequency of alleles associated with more efficient arsenic metabolism reported so far. Our data support the idea that arsenic exposure has been a driver for human adaptation to tolerate arsenic through more efficient arsenic detoxification in different Andean populations.

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 in the water and agricultural crop production system: Bangladesh perspectives

The presence of high levels of carcinogenic metalloid arsenic (As) in the groundwater system of Bangladesh has been considered as one of the major environmental disasters in this region. Many parts of Bangladesh have extensively reported the presence of high levels of arsenic in the groundwater due to both geological and anthropogenic activities. In this paper, we reviewed the available literature and scientific information regarding arsenic pollution in Bangladesh, including arsenic chemistry and occurrences. Along with using As-rich groundwater as a drinking-water source, the agricultural activities and especially irrigation have greatly depended on the groundwater resources in this region due to high water demands for ensuring food security. A number of investigations in Bangladesh have shown that high arsenic content in both soil and groundwater may result in high levels of arsenic accumulation in different plants, including cereals and vegetables. This review provides information regarding arsenic accumulation in major rice varieties, soil-groundwater-rice arsenic interaction, and past arsenic policies and plans, as well as previously implemented arsenic mitigation options for both drinking and irrigation water systems in Bangladesh. In conclusion, this review highlights the importance and necessity for more in-depth studies as well as more effective arsenic mitigation action plans to reduce arsenic incorporation in the food chain of Bangladesh.

A mass-balance model to assess arsenic exposure from multiple wells in Bangladesh

BACKGROUND

Water arsenic (As) sources beyond a rural household's primary well may be a significant source for certain individuals, including schoolchildren and men working elsewhere.

OBJECTIVE

To improve exposure assessment by estimating the fraction of drinking water that comes from wells other than the household's primary well in a densely populated area.

METHODS

We use well water and urinary As data collected in 2000-2001 within a 25 km² area of Araihazar upazila, Bangladesh, for 11,197 participants in the Health Effects of Arsenic Longitudinal Study (HEALS). We estimate the fraction of water that participants drink from different wells by imposing a long-term mass-balance constraint for both As and water.

RESULTS

The mass-balance model suggest that, on average, HEALS participants obtain 60-75% of their drinking water from their primary household wells and 25-40% from other wells, in addition to water from food and cellular respiration. Because of this newly quantified contribution from other wells, As in drinking water rather than rice was identified as the largest source of As exposure at baseline for HEALS participants with a primary household well containing ≤50 µg/L As.

SIGNIFICANCE

Dose-response relationships for As based on water As should take into account other wells. The mass-balance approach could be applied to study other toxicants.

Infant infections, respiratory symptoms, and allergy in relation to timing of rice cereal introduction in a United States cohort

Rice products marketed in the USA, including baby rice cereal, contain inorganic arsenic, a putative immunotoxin. We sought to determine whether the timing of introduction of rice cereal in the first year of life influences occurrence of infections, respiratory symptoms, and allergy. Among 572 infants from the New Hampshire Birth Cohort Study, we used generalized estimating equation, adjusted for maternal smoking during pregnancy, marital status, education attainment, pre-pregnancy body mass index, maternal age at enrollment, infant birth weight, and breastfeeding history. Among 572 infants, each month earlier of introduction to rice cereal was associated with increased risks of subsequent upper respiratory tract infections (relative risk, RR = 1.04; 95% CI: 1.00-1.09); lower respiratory tract infections (RR = 1.19; 95% CI: 1.02-1.39); acute respiratory symptoms including wheeze, difficulty breathing, and cough (RR = 1.10; 95% CI: 1.00-1.22); fever requiring a prescription medicine (RR = 1.22; 95% CI: 1.02-1.45) and allergy diagnosed by a physician (RR = 1.20; 95% CI: 1.06-1.36). No clear associations were observed with gastrointestinal symptoms. Our findings suggest that introduction of rice cereal earlier may influence infants' susceptibility to respiratory infections and allergy.

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.

Prenatal arsenic exposure interferes in postnatal immunocompetence despite an absence of ongoing arsenic exposure

Arsenic (As) readily crosses the placenta and exposure of the fetus may cause adverse consequences later in life, including immunomodulation. In the current study, the question was asked how the immune repertoire might respond in postnatal life when there is no further As exposure. Here, pregnant mice (Balb/c [H-2^d]) were exposed to arsenic trioxide (As₂O₃) through their drinking water from time of conception until parturition. Their offspring, 4-week-old mice who had not been exposed again to As, were used for functional analyses of innate, humoral and cellular immunity. Compared to cells from non-As-exposed dam offspring, isolated peritoneal macro-phages (Mϕ) displayed no differences in T-cell stimulating ability. Levels of circulating IgG_2a but not IgG₁ were decreased in As-exposed dam offspring as compared to control offspring counterparts. Mixed-leukocyte reactions (MLR) indicated that CD4⁺ T-cells from the prenatal As-exposed mice were significantly less responsive to allogenic stimulation as evidenced by decreases in interferon (IFN)-γ and IL-2 production and in expression of CD44 and CD69 (but not CD25) activation markers. Interestingly, the Mϕ from the prenatal As-exposed mice were capable of stimulating normal allogenic T-cells, indicating that T-cells from these mice were refractory to allogenic signals. There was also a significant decrease in absolute numbers of splenic CD4⁺ and CD8⁺ T-cells due to prenatal As exposure (as compared to control). Lastly, the impaired immune function of the prenatal As-exposed mice was correlated with a very strong susceptibility to Escherichia coli infection. Taken together, the data from this study clearly show that in utero As exposure may continue to perpetuate a dampening effect on the immune repertoire of offspring, even into the early stages of postnatal life.

The role of H3K9me2-regulated base excision repair genes in the repair of DNA damage induced by arsenic in HaCaT cells and the effects of Ginkgo biloba extract intervention

Arsenic is an established human carcinogen that can induce DNA damage; however, the precise mechanism remains unknown. Histone modification is of great significance in chemical toxicity and carcinogenesis. To investigate the role of histone H3K9me2 in arsenic-induced DNA damage, HaCaT cells were exposed to sodium arsenite in this study, and the results showed that the enrichment level of H3K9me2 at the N-methylated purine-DNA-glycosylase (MPG), X-ray repair cross-complementary gene 1 (XRCC1), and polyadenylate diphosphate ribose polymerase-1 (PARP1) promoter regions of base-excision repair (BER) genes was increased, which inhibited the expression of these BER genes, thereby inhibiting the repair of DNA damage and aggravating the DNA damage. Furthermore, the molecular mechanism by which H3K9me2 participates in the BER repair of arsenic-induced DNA damage was verified based on functional loss and gain experiments. In addition, Ginkgo biloba extract can upregulate the expression of MPG, XRCC1, and PARP1 and ameliorate cell DNA damage by reducing the enrichment of H3K9me2 at repair gene promoter regions.

Maternal and childhood exposure to inorganic arsenic and airway allergy - A 15-Year birth cohort follow-up study

BACKGROUND

The prevalence of allergic diseases in children has increased globally. Early-life exposure to inorganic arsenic has been found to be associated with impaired immune function and decreased lung function in children; however, the results are inconsistent. We aimed to evaluate the effect of prenatal and childhood exposure to inorganic arsenic on allergic diseases in children, through a 15-year follow-up birth cohort study, conducted in central Taiwan.

METHODS

Children born to women enrolled in the Taiwan Maternal and Infant Cohort Study (TMICS-pilot) from December 2000 to November 2001 were recruited and followed every 2-3 years until the age of 14 years. Urinary specimens were collected in the pregnant women during the 3rd trimester and the followed children. Diagnoses of allergic diseases were based on physician diagnoses using the International Study of Asthma and Allergies in Childhood questionnaire. Urinary arsenic speciation was performed using high-performance liquid chromatography and inductively coupled plasma dynamic reaction cell mass spectrophotometry.

RESULTS

Of the 261 children from 358 mother-infant pairs for this study, those with asthma and allergic rhinitis reported a higher prevalence of maternal allergy (49.47%) than did non-allergic children (29.81%). In the fully adjusted model, levels of maternal urine (iAs + MMA + DMA) greater than the median were found to be significantly associated with an increased risk of asthma (OR = 4.28; 95% CI 1.32, 13.85). Levels of urinary (iAs + MMA + DMA) in children higher than the median were associated with an increased risk of allergic rhinitis (OR = 2.26; 95% CI 1.20, 4.26).

CONCLUSION

Prenatal and childhood exposure to inorganic arsenic were found to be significantly associated with the occurrence of asthma and allergic rhinitis in children, respectively. Further large cohort follow-up studies are important to validate the association between inorganic arsenic exposure and allergic diseases in children.

Global impact of atmospheric arsenic on health risk: 2005 to 2015

Arsenic is a toxic pollutant commonly found in the environment. Most of the previous studies on arsenic pollution have primarily focused on arsenic contamination in groundwater. In this study, we examine the impact on human health from atmospheric arsenic on the global scale. We first develop an improved global atmospheric arsenic emission inventory and connect it to a global model (Goddard Earth Observing System [GEOS]-Chem). Model evaluation using observational data from a variety of sources shows the model successfully reproduces the spatial distribution of atmospheric arsenic around the world. We found that for 2005, the highest airborne arsenic concentrations were found over Chile and eastern China, with mean values of 8.34 and 5.63 ng/m3, respectively. By 2015, the average atmospheric arsenic concentration in India (4.57 ng/m3) surpassed that in eastern China (4.38 ng/m3) due to the fast increase in coal burning in India. Our calculation shows that China has the largest population affected by cancer risk due to atmospheric arsenic inhalation in 2005, which is again surpassed by India in 2015. Based on potential exceedance of health-based limits, we find that the combined effect by including both atmospheric and groundwater arsenic may significantly enhance the risks, due to carcinogenic and noncarcinogenic effects. Therefore, this study clearly implies the necessity in accounting for both atmospheric and groundwater arsenic in future management.

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.

Prospective cohort study of respiratory effects at ages 14 to 26 following early life exposure to arsenic in drinking water

BACKGROUND

We previously reported chronic respiratory effects in children who were then 7-17 years of age in Matlab, Bangladesh. One group of children had been exposed to high concentrations of arsenic in drinking water in utero and early childhood (average 436 µg/L), and the other group of children were never known to have been exposed to >10 µg/L. The exposed children, both males and females, had marked increases in chronic respiratory symptoms.

METHODS

The current study involves a further follow-up of these children now 14-26 years of age with 463 located and agreeing to participate. They were interviewed for respiratory symptoms and lung function was measured. Data were collected on smoking, body mass index (BMI), and number of rooms in the house as a measure of socioeconomic status.

RESULTS

Respiratory effects were still present in males but not females. In the high exposure group (>400 µg/L in early life) the odds ratio (OR) among male participants for dry cough in the last 12 months was 2.36 (95% confidence interval [CI] = 1.21, 4.63, P = 0.006) and for asthma OR = 2.51 (95% CI = 1.19, 5.29, P = 0.008). Forced vital capacity (FVC) was reduced in males in the early life high-exposure group compared with those never exposed (-95ml, P = 0.04), but not in female participants.

CONCLUSIONS

By the age range 14-26, there was little remaining evidence of chronic respiratory effects in females but pronounced effects persisted in males. Mechanisms for the marked male female differences warrant further investigation along with further follow-up to see if respiratory effects continue in males.

Intra- and Interlaboratory Evaluation of an Assay of Soil Arsenic Relative Bioavailability in Mice

Hand-to-mouth activity in children can be an important route for ingestion of soil and dust contaminated with inorganic arsenic. Estimating the relative bioavailability of arsenic present in these media is a critical element in assessing the risks associated with aggregate exposure to this toxic metalloid during their early life. Here, we evaluated the performance of a mouse assay for arsenic bioavailability in two laboratories using a suite of 10 soils. This approach allowed us to examine both intralaboratory and interlaboratory variations in assay performance. Use of a single vendor for preparation of all amended test diets and of a single laboratory for arsenic analysis of samples generated in the participating laboratories minimized contributions of these potential sources of variability in assay performance. Intralaboratory assay data showed that food and water intake and cumulative urine and feces production remained stable over several years. The stability of these measurements accounted for the reproducibility of estimates of arsenic bioavailability obtained from repeated intralaboratory assays using sodium arsenate or soils as the test material. Interlaboratory comparisons found that estimates of variables used to evaluate assay performance (recovery and urinary excretion factor) were similar in the two laboratories. For all soils, estimates of arsenic relative bioavailability obtained in the two laboratories were highly correlated (r² = 0.94 and slope = 0.9) in a linear regression model. Overall, these findings show that this mouse assay for arsenic bioavailability provides reproducible estimates using a variety of test soils. This robust model may be adaptable for use in other laboratory settings.

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.

Long-Term Health Effects and Underlying Biological Mechanisms of Developmental Exposure to Arsenic

PURPOSE OF REVIEW

Exposure to inorganic arsenic (iAs) via drinking water represents a significant global public health threat with chronic exposure associated with cancer, skin lesions, neurological impairment, and cardiovascular diseases. Particularly susceptible populations include the developing fetus and young children. This review summarizes some of the critical studies of the long-term health effects and underlying biological mechanisms related to developmental exposure to arsenic. It also highlights the complex factors, such as the sex of the exposed individual, that contribute to susceptibility to the later life health effects of iAs.

RECENT FINDINGS

Studies in animal models, as well as human population-based studies, have established that prenatal and early life iAs exposures are associated with long-term effects, and many of these effects display sexually dimorphic responses. As an underlying molecular basis, recent epidemiologic and toxicologic studies have demonstrated that changes to the epigenome may play a key mechanistic role underlying many of the iAs-associated health outcomes. Developmental exposure to iAs results in early and later life health effects. Mechanisms underlying these outcomes are likely complex, and include disrupted key biological pathways with ties to the epigenome. This highlights the importance of continued research, particularly in animal models, to elucidate the important underpinnings (e.g., timing of exposure, metabolism, dose) of these complex health outcomes and to identify the biological mechanisms underlying sexual dimorphism in iAs-associated diseases. Future research should investigate preventative strategies for the protection from the detrimental health endpoints associated with early life exposure to iAs. Such strategies could include potential interventions focused on dietary supplementation for example the adoption of a folate-rich diet.

Arsenite suppresses NO production evoked by lipopolysaccharide and poly(I:C) via the suppression of interferon-β expression in RAW264.7 cells

Immunological functions are disturbed in humans who have been chronically exposed to arsenic via contaminated groundwater. Little is known about the specific mechanisms underlying the impairment of immunological defense system caused by arsenic. The activation of macrophage cells upon infection with bacteria and viruses plays important roles in the defense against these pathogens. Here we show that exposure to arsenite (As(III)) suppresses nitric oxide (NO) production in murine RAW264.7 macrophage cells stimulated with lipopolysaccharide (LPS) and poly(I:C), the compounds mimicking bacterial and viral infection, respectively. As(III) suppressed the LPS- or poly(I:C)-evoked induction of inducible NO synthase (iNOS) without affecting the transactivation of NF-κB. As the interferon (IFN)-β/STAT1 pathway is also involved in the induction of iNOS in addition to NF-κB, we examined the effects of As(III) on the expression and secretion of IFN-β, the expression of the components of IFN-α/β receptor, the phosphorylation of STAT1, and the levels of cytokines involved in STAT1 activation. The results showed that the expression and secretion of IFN-β were specifically suppressed by As(III) treatment in RAW264.7 cells stimulated with LPS or poly(I:C). These results suggest that As(III) suppresses the expression and secretion of IFN-β, leading to the reduced STAT1 activation and consequently the reduced iNOS induction in macrophage cells. Our data suggest an important role of the arsenic-induced suppression of IFN-β on the disturbances in immunological defense against both bacteria and viruses.

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.

Age at Exposure to Arsenic in Water and Mortality 30-40 Years After Exposure Cessation

Arsenic in drinking water is known to cause cancer and noncancer diseases, but little is known about its association with age at exposure. Here, we investigated age at arsenic exposure and mortality in Antofagasta, Chile, 30-40 years after a distinct period of very high water arsenic concentrations (1958-1970). We calculated standardized mortality ratios (SMRs) comparing Antofagasta with the rest of Chile for 2001-2010 by sex and age at potential first exposure. A remarkable relationship with age at first exposure was found for bronchiectasis, with increased risk in adults 30-40 years after exposure being confined to those who were in utero (SMR = 11.7, 95% confidence interval (CI): 4.3, 25.4) or aged 1-10 years (SMR = 5.4, 95% CI: 1.1, 15.8) during the high-exposure period. Increased SMRs for lung, bladder, and laryngeal cancer were evident for exposures starting at all ages, but the highest SMRs were for exposures beginning at birth (for bladder cancer, SMR = 16.0 (95% CI: 10.3, 23.8); for laryngeal cancer, SMR = 6.8 (95% CI: 2.2, 15.8); for lung cancer, SMR = 3.8 (95% CI: 2.9, 4.9)). These findings suggest that interventions targeting early-life arsenic exposure could have major impacts in reducing long-term mortality due to arsenic 30-40 years after exposure ends.

A comparison of arsenic exposure in young children and home water arsenic in two rural West Texas communities

Background

In a previously conducted Health Impact Assessment of a well-water dependent southwest community, arsenic (As) levels greater than the EPA Maximum Contaminant Level (10 μg/L) were identified in home water samples. The goals of this study were to test whether children from the previously studied well-water dependent community (Community 1) had higher blood As levels than children from a demographically similar and geographically nearby community dependent on a municipal water supply (Community 2); to test whether home water As levels predicted child As blood levels; and to examine how child As blood levels changed over time.

Methods

This was an observational study of 252 children aged 4 to 12 years from two communities. Children were recruited through elementary schools and tested during the school day; 204 children participated in follow-up testing. Home water samples were collected according to U.S. Environmental Protection agency recommended procedures. Child heavy metal blood levels and home water sample heavy metal levels were analyzed using inductively coupled plasma mass spectrometry. General linear regression analysis was used to test the influence of community on child As levels, and to examine the contribution of home water As levels to child blood As levels.

Results

Arsenic was detectable in all children tested. Blood levels ranged from 0.09–2.61 μg/dL; approximately 31% of children tested at Time I (79/252) had blood As values above the current acceptable limit (1.2 μg/dL). Approximately 8% of household water samples (6/76) had As levels higher than 10 μg/L. Community did not predict child blood As levels; seasonal effects differed by Community. At Time II, child blood As levels were higher in Community 2 than in Community 1.

Conclusion

A large proportion of children in the communities tested had As exposure. Home water As levels did not predict child blood As levels. Fluctuating child blood As levels by season and over time suggested the contribution of multiple factors and the need for further studies.

Arsenic and Immune Response to Infection During Pregnancy and Early Life

PURPOSE OF REVIEW

Arsenic, a known carcinogen and developmental toxicant, is a major threat to global health. While the contribution of arsenic exposure to chronic diseases and adverse pregnancy and birth outcomes is recognized, its ability to impair critical functions of humoral and cell-mediated immunity-including the specific mechanisms in humans-is not well understood. Arsenic has been shown to increase risk of infectious diseases that have significant health implications during pregnancy and early life. Here, we review the latest research on the mechanisms of arsenic-related immune response alterations that could underlie arsenic-associated increased risk of infection during the vulnerable periods of pregnancy and early life.

RECENT FINDINGS

The latest evidence points to alteration of antibody production and transplacental transfer as well as failure of T helper cells to produce IL-2 and proliferate. Critical areas for future research include the effects of arsenic exposure during pregnancy and early life on immune responses to natural infection and the immunogenicity and efficacy of vaccines.

The impact of BMI on non-malignant respiratory symptoms and lung function in arsenic exposed adults of Northern Chile

BACKGROUND

Elevated body mass index (BMI) and arsenic are both associated with cancer and with non-malignant lung disease. Using a unique exposure situation in Northern Chile with data on lifetime arsenic exposure, we previously identified the first evidence of an interaction between arsenic and BMI for the development of lung cancer.

OBJECTIVES

We examined whether there was an interaction between arsenic and BMI for the development of non-malignant lung disease.

METHODS

Data on lifetime arsenic exposure, respiratory symptoms, spirometry, BMI, and smoking were collected from 751 participants from cities in Northern Chile with varying levels of arsenic water concentrations. Spirometry values and respiratory symptoms were compared across subjects in different categories of arsenic exposure and BMI.

RESULTS

Adults with both a BMI above the 90th percentile (>33.9kg/m²) and arsenic water concentrations ≥11µg/L exhibited high odds ratios (ORs) for cough (OR = 10.7, 95% confidence interval (CI): 3.03, 50.1), shortness of breath (OR = 14.2, 95% CI: 4.79, 52.4), wheeze (OR = 14.4, 95% CI: 4.80, 53.7), and the combined presence of any respiratory symptom (OR = 9.82, 95% CI: 4.22, 24.5). In subjects with lower BMIs, respiratory symptom ORs for arsenic water concentrations ≥11µg/L were markedly lower. In never-smokers, reductions in forced vital capacity associated with arsenic increased as BMI increased. Analysis of the FEV₁/FVC ratio in never-smokers significantly increased as BMI and arsenic concentrations increased. Similar trends were not observed for FEV₁ alone or in ever-smokers.

CONCLUSIONS

This study provides preliminary evidence that BMI may increase the risk for arsenic-related non-malignant respiratory disease.

Early life arsenic exposure, infant and child growth, and morbidity: a systematic review

Epidemiological studies have suggested a negative association between early life arsenic exposure and fetal size at birth, and subsequently with child morbidity and growth. However, our understanding of the relationship between arsenic exposure and morbidity and growth is limited. This paper aims to systematically review original human studies with an analytical epidemiological study design that have assessed arsenic exposure in fetal life or early childhood and evaluated the association with one or several of the following outcomes: fetal growth, birth weight or other birth anthropometry, infant and child growth, infectious disease morbidity in infancy and early childhood. A literature search was conducted in PubMed, TOXLINE, Web of Science, SciFinder and Scopus databases filtered for human studies. Based on the predefined eligibility criteria, two authors independently evaluated the studies. A total of 707 studies with morbidity outcomes were identified, of which six studies were eligible and included in this review. For the growth outcomes, a total of 2959 studies were found and nine fulfilled the criteria and were included in the review. A majority of the papers (10/15) emanated from Bangladesh, three from the USA, one from Romania and one from Canada. All included studies on arsenic exposure and morbidity showed an increased risk of respiratory tract infections and diarrhea. The findings in the studies of arsenic exposure and fetal, infant, and child growth were heterogeneous. Arsenic exposure was not associated with fetal growth. There was limited evidence of negative associations between arsenic exposures and birth weight and growth during early childhood. More studies from arsenic-affected low- and middle-income countries are needed to support the generalizability of study findings.

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.

Humoral Immunity in Arsenic-Exposed Children in Rural Bangladesh: Total Immunoglobulins and Vaccine-Specific Antibodies

BACKGROUND

Early-life arsenic exposure has been associated with reduced cell-mediated immunity, but little is known about its effects on humoral immunity.

OBJECTIVE

We evaluated whether prenatal and childhood arsenic exposure was associated with humoral immune function in school-aged children.

METHODS

Children born in a prospective mother–child cohort in rural Bangladesh were immunized with measles, mumps, and rubella (MMR) vaccines at 9 years of age (n=525). Arsenic exposure was assessed in urine (U-As), from mothers during pregnancy and their children at 4.5 and 9 years of age. Total IgG (tIgG), tIgE, tIgA, and MMR-specific IgG concentrations were measured in plasma using immunoassays.

RESULTS

Arsenic exposure was positively associated with child tIgG and tIgE, but not tIgA. The association with tIgG was mainly apparent in boys (p for interaction=0.055), in whom each doubling of maternal U-As was related to an increase in tIgG by 28 mg/dL. The associations of U-As at 9 years with tIgG and tIgE were evident in underweight children (p for interaction <0.032). Childhood arsenic exposure tended to impair mumps-specific vaccine response, although the evaluation was complicated by high preimmunization titers. Postimmunization mumps–specific IgG titers tended to decrease with increasing U-As at 4.5 and 9 years of age [regression coefficient (β)=−0.16; 95% confidence interval (CI): −0.33, 0.01; p=0.064 and β=−0.12; 95% CI: −0.27, −0.029; p=0.113, respectively) in 25% children with the lowest preexisting mumps-specific IgG titers.

CONCLUSIONS

Arsenic exposure increased tIgG and tIgE in plasma, and tended to decrease mumps-specific IgG in children at 9 years of age. https://doi.org/10.1289/EHP318.

Arsenic exposure alters lung function and airway inflammation in children: A cohort study in rural Bangladesh

Exposure to arsenic has been associated with increased risk of reduced lung function in adults, but the adverse impacts in early life are unclear. We aim to examine whether prenatal and childhood arsenic exposure is associated with reduced lung function and increased airway inflammation in school-aged children. Children born in the MINIMat cohort in rural Bangladesh were evaluated at 9years of age (n=540). Arsenic exposure was assessed in urine (U-As) that was collected from mothers during early pregnancy and their children aged 4.5 and 9years. In the 9-year-old children, lung function was assessed using spirometry and airway inflammation was assessed by the NIOX MINO system. C-reactive protein (CRP) and Clara cell secretory protein (CC16) concentrations were measured in plasma by immunoassays. The U-As concentrations in 9-year-old children were lower (median 53μg/l) compared to their mothers (median 76μg/l). Maternal U-As (log₂ transformed) was inversely associated with forced vital capacity (FVC) and forced expiratory volume at 1s (FEV1) (β=-12; 95% CI: -22, -1.5; p=0.031 and β=-12; 95% CI: -22, -1.9; p=0.023, respectively) in all children, and the associations were stronger in boys and among children with adequate height and weight, as well as among those whose mothers had higher percentages of methylarsonic acid (MMA) and lower percentages of dimethylarsinic acid (DMA). U-As (log₂ transformed) at 4.5 and 9years was positively associated with fractional exhaled nitric oxide (FE_NO) concentrations in boys (β=0.89; 95% CI: 0.13, 1.66; p=0.022 and β=0.88; 95% CI: 0.16, 1.61; p=0.017, respectively) but not in girls. Increased CC16 concentrations were associated with higher lung function indices. In conclusion, our findings suggest that prenatal arsenic exposure is related to impaired lung function, while childhood exposure may increase airway inflammation, particularly in boys.

Molecular insight of arsenic-induced carcinogenesis and its prevention

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

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.

Developmental Windows of Susceptibility to Inorganic Arsenic: A Survey of Current Toxicologic and Epidemiologic Data

Globally, millions of people are exposed to elevated levels of inorganic arsenic (iAs) via drinking water. Exposure to iAs is associated with a wide range of negative health outcomes, including cancers, skin lesions, neurological impairment, cardiovascular diseases, and an increased susceptibility to infection. Among those exposed to iAs, the developing fetus and young children represent particularly sensitive subpopulations. Specifically, it has been noted in animal models and human populations that prenatal and early life iAs exposures are associated with diseases occurring during childhood and later in life. Recent epidemiologic and toxicologic studies have also demonstrated that epigenetic alterations may play a key mechanistic role underlying many of the iAs-associated health outcomes, including the carcinogenic and immunologic effects of exposure. This review summarizes some of the key studies related to prenatal and early life iAs exposure and highlights the complexities in isolating the precise developmental windows of exposure associated with these health outcomes.

Effects of health intervention programs and arsenic exposure on child mortality from acute lower respiratory infections in rural Bangladesh

BACKGROUND

Respiratory infections continue to be a public health threat, particularly to young children in developing countries. Understanding the geographic patterns of diseases and the role of potential risk factors can help improve future mitigation efforts. Toward this goal, this paper applies a spatial scan statistic combined with a zero-inflated negative-binomial regression to re-examine the impacts of a community-based treatment program on the geographic patterns of acute lower respiratory infection (ALRI) mortality in an area of rural Bangladesh. Exposure to arsenic-contaminated drinking water is also a serious threat to the health of children in this area, and the variation in exposure to arsenic must be considered when evaluating the health interventions.

METHODS

ALRI mortality data were obtained for children under 2 years old from 1989 to 1996 in the Matlab Health and Demographic Surveillance System. This study period covers the years immediately following the implementation of an ALRI control program. A zero-inflated negative binomial (ZINB) regression model was first used to simultaneously estimate mortality rates and the likelihood of no deaths in groups of related households while controlling for socioeconomic status, potential arsenic exposure, and access to care. Next a spatial scan statistic was used to assess the location and magnitude of clusters of ALRI mortality. The ZINB model was used to adjust the scan statistic for multiple social and environmental risk factors.

RESULTS

The results of the ZINB models and spatial scan statistic suggest that the ALRI control program was successful in reducing child mortality in the study area. Exposure to arsenic-contaminated drinking water was not associated with increased mortality. Higher socioeconomic status also significantly reduced mortality rates, even among households who were in the treatment program area.

CONCLUSION

Community-based ALRI interventions can be effective at reducing child mortality, though socioeconomic factors may continue to influence mortality patterns. The combination of spatial and non-spatial methods used in this paper has not been applied previously in the literature, and this study demonstrates the importance of such approaches for evaluating and improving public health intervention programs.

Behavioral Determinants of Switching to Arsenic-Safe Water Wells

More than 100 million people globally are estimated to be exposed to arsenic in drinking water that exceeds the World Health Organization guideline of 10 µg/L. In an effort to develop and test a low-cost sustainable approach for water arsenic testing in Bangladesh, we conducted a randomized controlled trial which found arsenic educational interventions when combined with fee-based water arsenic testing programs led to nearly all households buying an arsenic test for their drinking water sources (93%) compared with only 53% when fee-based arsenic testing alone was offered. The aim of the present study was to build on the findings of this trial by investigating prospectively the psychological factors that were most strongly associated with switching to arsenic-safe wells in response to these interventions. Our theoretical framework was the RANAS (risk, attitude, norm, ability, and self-regulation) model of behavior change. In the multivariate logistic regression model of 285 baseline unsafe well users, switching to an arsenic-safe water source was significantly associated with increased instrumental attitude (odds ratio [OR] = 9.12; 95% confidence interval [CI] = [1.85, 45.00]), descriptive norm (OR = 34.02; 95% CI = [6.11, 189.45]), coping planning (OR = 11.59; 95% CI = [3.82, 35.19]), and commitment (OR = 10.78; 95% CI = [2.33, 49.99]). In addition, each additional minute from the nearest arsenic-safe drinking water source reduced the odds of switching to an arsenic-safe well by more than 10% (OR = 0.89; 95% CI = [0.87, 0.92]). Future arsenic mitigation programs should target these behavioral determinants of switching to arsenic-safe water sources.

Infant Infections and Respiratory Symptoms in Relation to in Utero Arsenic Exposure in a U.S. Cohort

BACKGROUND

Arsenic has been linked to disrupted immune function and greater infection susceptibility in highly exposed populations. Well arsenic levels above the U.S. EPA limit occur in our U.S. study area and are of particular concern for pregnant women and infants.

OBJECTIVES

We investigated whether in utero arsenic exposure affects the risk of infections and respiratory symptoms over the first year of life.

METHODS

We prospectively obtained information on infant infections and symptoms, including their duration and treatment (n = 412) at 4, 8, and 12 months using a parental telephone survey. Using generalized estimating equation models adjusted for potential confounders, we evaluated the association between maternal pregnancy urinary arsenic and infant infections and symptoms over the first year.

RESULTS

Each doubling of maternal urinary arsenic was related to increases in the total number of infections requiring prescription medication in the first year [relative risk (RR) = 1.1; 95% CI: 1.0, 1.2]. Urinary arsenic was related specifically to respiratory symptoms (difficulty breathing, wheezing, and cough) lasting ≥ 2 days or requiring prescription medication (RR = 1.1; 95% CI: 1.0, 1.2; and RR = 1.2; 95% CI: 1.0, 1.5, respectively), and wheezing lasting ≥ 2 days, resulting in a doctor visit or prescription medication treatment (RR = 1.3; 95% CI: 1.0, 1.7; RR = 1.3; 95% CI: 1.0, 1.8, and RR = 1.5; 95% CI: 1.0, 2.2, respectively). Associations also were observed with diarrhea (RR = 1.4; 95% CI: 1.1, 1.9) and fever resulting in a doctor visit (RR = 1.2; 95% CI: 1.0, 1.5).

CONCLUSIONS

In utero arsenic exposure was associated with a higher risk of infection during the first year of life in our study population, particularly infections requiring medical treatment, and with diarrhea and respiratory symptoms.

CITATION

Farzan SF, Li Z, Korrick SA, Spiegelman D, Enelow R, Nadeau K, Baker E, Karagas MR. 2016. Infant infections and respiratory symptoms in relation to in utero arsenic exposure in a U.S.

COHORT

Environ Health Perspect 124:840-847; http://dx.doi.org/10.1289/ehp.1409282.

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.

Arsenic Metabolism in Children Differs From That in Adults

Arsenic toxicity in adults is associated with methylation efficiency, influenced by factors such as gender, genetics, and nutrition. The aim of this study was to evaluate influencing factors for arsenic metabolism in children. For 488 children (9 years), whose mothers participated in a study on arsenic exposure during pregnancy (nested into the MINIMat trial) in rural Bangladesh, we measured urinary concentrations of inorganic arsenic (iAs) and its metabolites methylarsonic acid (MMA) and dimethylarsinic acid (DMA) by HPLC-HG-ICPMS. Methylation efficiency was assessed by relative amounts (%) of the metabolites. We evaluated the impact of factors such as maternal urinary metabolite pattern, arsenic exposure, gender, socioeconomic status, season of sampling, and nutritional factors, including erythrocyte selenium (Ery-Se), and plasma folate and vitamin B12.

Children had higher %DMA and lower %iAs in urine compared to their mothers, unrelated to their lower exposure [median urinary arsenic (U-As) 53 vs 78 µg/l]. Surprisingly, selenium status (Ery-Se) was strongly associated with children’s arsenic methylation; an increase in Ery-Se from the 5–95th percentile was associated with: +1.8 percentage points (pp) for %iAs (P  =  .001), +1.4 pp for %MMA (P  =  .003), and −3.2 pp for %DMA (P  <  .001). Despite this, Ery-Se was positively associated with U-As (5–95th percentile: +41 µg/l, P  =  .026). As expected, plasma folate was inversely associated with %iAs (5–95th percentile: −1.9 pp, P  =  .001) and positively associated with %DMA (5–95th percentile: +2.2 pp, P  =  .008). Children methylated arsenic more efficiently than their mothers. Also influencing factors, mainly selenium and folate, differed. This warrants further research.

Effects of in Utero Exposure to Arsenic during the Second Half of Gestation on Reproductive End Points and Metabolic Parameters in Female CD-1 Mice

BACKGROUND

Mice exposed to high levels of arsenic in utero have increased susceptibility to tumors such as hepatic and pulmonary carcinomas when they reach adulthood. However, the effects of in utero arsenic exposure on general physiological functions such as reproduction and metabolism remain unclear.

OBJECTIVES

We evaluated the effects of in utero exposure to inorganic arsenic at the U.S. Environmental Protection Agency (EPA) drinking water standard (10 ppb) and at tumor-inducing levels (42.5 ppm) on reproductive end points and metabolic parameters when the exposed females reached adulthood.

METHODS

Pregnant CD-1 mice were exposed to sodium arsenite [none (control), 10 ppb, or 42.5 ppm] in drinking water from gestational day 10 to birth, the window of organ formation. At birth, exposed offspring were fostered to unexposed dams. We examined reproductive end points (age at vaginal opening, reproductive hormone levels, estrous cyclicity, and fertility) and metabolic parameters (body weight changes, hormone levels, body fat content, and glucose tolerance) in the exposed females when they reached adulthood.

RESULTS

Arsenic-exposed females (10 ppb and 42.5 ppm) exhibited early onset of vaginal opening. Fertility was not affected when females were exposed to the 10-ppb dose. However, the number of litters per female was decreased in females exposed to 42.5 ppm of arsenic in utero. In both 10-ppb and 42.5-ppm groups, arsenic-exposed females had significantly greater body weight gain, body fat content, and glucose intolerance.

CONCLUSION

Our findings revealed unexpected effects of in utero exposure to arsenic: exposure to both a human-relevant low dose and a tumor-inducing level led to early onset of vaginal opening and to obesity in female CD-1 mice.

Mechanisms Underlying Latent Disease Risk Associated with Early-Life Arsenic Exposure: Current Research Trends and Scientific Gaps

BACKGROUND

Millions of individuals worldwide, particularly those living in rural and developing areas, are exposed to harmful levels of inorganic arsenic (iAs) in their drinking water. Inorganic As exposure during key developmental periods is associated with a variety of adverse health effects, including those that are evident in adulthood. There is considerable interest in identifying the molecular mechanisms that relate early-life iAs exposure to the development of these latent diseases, particularly in relationship to cancer.

OBJECTIVES

This work summarizes research on the molecular mechanisms that underlie the increased risk of cancer development in adulthood that is associated with early-life iAs exposure.

DISCUSSION

Epigenetic reprogramming that imparts functional changes in gene expression, the development of cancer stem cells, and immunomodulation are plausible underlying mechanisms by which early-life iAs exposure elicits latent carcinogenic effects.

CONCLUSIONS

Evidence is mounting that relates early-life iAs exposure and cancer development later in life. Future research should include animal studies that address mechanistic hypotheses and studies of human populations that integrate early-life exposure, molecular alterations, and latent disease outcomes.

Arsenic exposure is associated with pediatric pneumonia in rural Bangladesh: a case control study

BACKGROUND

Pneumonia is the leading cause of death for children under 5 years of age globally, making research on modifiable risk factors for childhood pneumonia important for reducing this disease burden. Millions of children globally are exposed to elevated levels of arsenic in drinking water. However, there is limited data on the association between arsenic exposure and respiratory infections, particularly among pediatric populations.

METHODS

This case control study of 153 pneumonia cases and 296 controls 28 days to 59 months of age in rural Bangladesh is the first to assess whether arsenic exposure is a risk factor for pneumonia in a pediatric population. Cases had physician diagnosed World Health Organization defined severe or very severe pneumonia. Urine collected during hospitalization (hospital admission time point) and 30 days later (convalescent time point) from cases and a single specimen from community controls was tested for urinary arsenic by graphite furnace atomic absorption.

RESULTS

The odds for pneumonia was nearly double for children with urinary arsenic concentrations higher than the first quartile (≥6 μg/L) at the hospital admission time point (Odd Ratio (OR):1.88 (95% Confidence Interval (CI): 1.01, 3.53)), after adjustment for urinary creatinine, weight for height, breastfeeding, paternal education, age, and number of people in the household. This was consistent with findings at the convalescent time point where the adjusted OR for children with urinary arsenic concentrations greater than the first quartile (≥6 μg/L) was 2.32 (95% CI: 1.33, 4.02).

CONCLUSION

We observed a nearly two times higher odds of pneumonia for children with creatinine adjusted urinary arsenic concentrations greater than the first quartile (≥6 μg/L) at the hospital admission time point. This novel finding suggests that low to moderate arsenic exposure may be a risk factor for pneumonia in children under 5 years of age.

Blood pressure, left ventricular geometry, and systolic function in children exposed to inorganic arsenic

BACKGROUND

Inorganic arsenic (iAs) is a ubiquitous element present in the groundwater worldwide. Cardiovascular effects related to iAs exposure have been studied extensively in adult populations. Few epidemiological studies have been focused on iAs exposure-related cardiovascular disease in children.

OBJECTIVE

In this study we investigated the association between iAs exposure, blood pressure (BP), and functional and anatomical echocardiographic parameters in children.

METHODS

A cross-sectional study of 161 children between 3 and 8 years was conducted in Central Mexico. The total concentration of arsenic (As) species in urine (U-tAs) was determined by hydride generation-cryotrapping-atomic absorption spectrometry and lifetime iAs exposure was estimated by multiplying As concentrations measured in drinking water by the duration of water consumption in years (LAsE). BP was measured by standard protocols, and M-mode echocardiographic parameters were determined by ultrasonography.

RESULTS

U-tAs concentration and LAsE were significantly associated with diastolic (DBP) and systolic blood pressure (SBP) in multivariable linear regression models: DBP and SBP were 0.013 (95% CI: 0.002, 0.024) and 0.021 (95% CI: 0.004, 0.037) mmHg higher in association with each 1-ng/mL increase in U-tAs (p < 0.025), respectively. Left ventricular mass (LVM) was significantly associated with LAsE [5.5 g higher (95% CI: 0.65, 10.26) in children with LAsE > 620 compared with < 382 μg/L-year; p = 0.03] in an adjusted multivariable model. The systolic function parameters left ventricular ejection fraction (EF) and shortening fraction were 3.67% (95% CI: -7.14, -0.20) and 3.41% (95% CI: -6.44, -0.37) lower, respectively, in children with U-tAs > 70 ng/mL compared with < 35 ng/mL.

CONCLUSION

Early-life exposure to iAs was significantly associated with higher BP and LVM and with lower EF in our study population of Mexican children.