Environmental exposure to arsenic and cadmium during pregnancy and fetal size: A longitudinal study in rural Bangladesh

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

BACKGROUND

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Maternal urinary cadmium levels during pregnancy associated with risk of sex-dependent birth outcomes from an e-waste pollution site in China

This study was to investigate whether exposure to cadmium (Cd) during pregnancy is associated with an increased risk of adverse birth outcomes in a sex-dependent manner. Cd concentrations in maternal urine (U-Cd) samples were measured in 237 subjects from Guiyu (e-waste area) and 212 subjects from Haojiang. A significance level of p <0.05 was used for all analyses. The maternal U-Cd levels in Guiyu residents were significantly higher than Haojiang. We found significant inverse associations between U-Cd concentrations and birth anthropometry (birth weight, birth length, Head Circumference and Apgar scores with 1min and 5 mins) in female neonates, but no significant associations were observed in male neonates except Apgar (1min) score after adjustment. The association was more pronounced among female neonates than male neonates, suggesting an association between Cd and adverse birth outcomes may be sex-specific.

Congenital heart defects of fetus after maternal exposure to organic and inorganic environmental factors: a cohort study

Objective

Maternal exposure to various contaminants has been reported to be correlated with congetinal heart defects (CHDs). In this study, the effect of maternal exposure to organic and inorganic environmental factors upon the incidence of CHDs was investigated. We conducted a retrospective birth cohort study of infants born in the Maternal and Child Health Hospital of Panyu District in Guangzhou.

Materials and Methods

A total of 5381 cases with complete medical records, including mothers, fathers, and infants, were enrolled. The relationship between maternal occupational exposure to hazardous substances and strong noise during pregnancy and CHDs was analyzed. Occupational exposure to hazardous substances increased the incidence of CHDs.

Results

Forty-eight of 145 mothers (33.1%) in the CHDs group worked in hazardous and strong noise factories, while the corresponding percentage mothers in the control group was 22.8% (1193/5236). The percentage of mothers with a history of contact with organic solvents and exposure to strong noise in the CHDs group was significantly higher than the control group. There was no significant difference in the histories of contact with heavy metals, high temperatures, and other extreme environments between two groups.

Conclusions

Hazardous substances in factories, especially organic solvents, were identified as potential risk factors for CHDs. Besides, exposure to high noise also increased the incidence of CHDs.

Prenatal Heavy Metal Exposure and Adverse Birth Outcomes in Myanmar: A Birth-Cohort Study

Arsenic, cadmium and lead are well-known environmental contaminants, and their toxicity at low concentration is the target of scientific concern. In this study, we aimed to identify the potential effects of prenatal heavy metal exposure on the birth outcomes among the Myanmar population. This study is part of a birth-cohort study conducted with 419 pregnant women in the Ayeyarwady Division, Myanmar. Face-to-face interviews were performed using a questionnaire, and maternal spot urine samples were collected at the third trimester. Birth outcomes were evaluated at delivery during the follow up. The median values of adjusted urinary arsenic, cadmium, selenium and lead concentration were 74.2, 0.9, 22.6 and 1.8 μg/g creatinine, respectively. Multivariable logistic regression revealed that prenatal cadmium exposure (adjusted odds ratio (OR) = 1.10; 95% confidence interval (CI): 1.01–1.21; p = 0.043), gestational age (adjusted OR = 0.83; 95% CI: 0.72–0.95; p = 0.009) and primigravida mothers (adjusted OR = 4.23; 95% CI: 1.31–13.65; p = 0.016) were the predictors of low birth weight. The present study identified that Myanmar mothers were highly exposed to cadmium. Prenatal maternal cadmium exposure was associated with an occurrence of low birth weight.

Investigating causal relation between prenatal arsenic exposure and birthweight: Are smaller infants more susceptible?

BACKGROUND

Shortening of gestation and intrauterine growth restriction (IUGR) are the two main determinants of birthweight. Low birthweight has been linked with prenatal arsenic exposure, but the causal relation between arsenic and birthweight is not well understood.

OBJECTIVES

We applied a quantile causal mediation analysis approach to determine the association between prenatal arsenic exposure and birthweight in relation to shortening of gestation and IUGR, and whether the susceptibility of arsenic exposure varies by infant birth sizes.

METHODS

In a longitudinal birth cohort in Bangladesh, we measured arsenic in drinking water (n=1182) collected at enrollment and maternal toenails (n=1104) collected ≤1-month postpartum using inductively coupled plasma mass spectrometry. Gestational age was determined using ultrasound at ≤16weeks' gestation. Demographic information was collected using a structured questionnaire.

RESULTS

Of 1184 singleton livebirths, 16.4% (n=194) were low birthweight (<2500g), 21.9% (n=259) preterm (<37weeks' gestation), and 9.2% (n=109) both low birthweight and preterm. The median concentrations of arsenic in drinking water and maternal toenails were 2.2μg/L (range: below the level of detection [LOD]-1400) and 1.2μg/g (range: <LOD-46.6), respectively. Prenatal arsenic exposure was negatively associated with birthweight, where the magnitude of the association varied across birthweight percentiles. The effect of arsenic on birthweight mediated via shortening of gestation affected all infants irrespective of birth sizes (β range: 10th percentile=-19.7g [95% CI: -26.7, -13.3] to 90th percentile=-10.9g [95% CI: -18.5, -5.9] per natural log water arsenic increase), whereas the effect via pathways independent of gestational age affected only the smaller infants (β range: 10th percentile=-28.0g [95% CI: -43.8, -9.9] to 20th percentile=-14.9g [95% CI: -30.3, -1.7] per natural log water arsenic increase). Similar pattern was observed for maternal toenail arsenic.

CONCLUSIONS

The susceptibility of prenatal arsenic exposure varied by infant birth sizes, placing smaller infants at greater risk of lower birthweight by shortening of gestation and possibly growth restriction. It is important to mitigate prenatal arsenic exposure to improve perinatal outcomes in Bangladesh.

Elemental content of the placenta: A comparison between two high-risk obstetrical populations, adult women carrying multiples and adolescents carrying singletons

BACKGROUND

The placenta is responsible for the exchange of nutrients and for preventing harmful compounds from entering the fetal circulation. With increasing industrialization, exposures to commercial and toxic metals become a concern for both pregnant women and those planning a pregnancy. The understanding of transport mechanisms and pharmacokinetics for most inorganic elements is incomplete and limited to normal term deliveries.

OBJECTIVES

To obtain novel data on 46 inorganic elements in placentae from two high-risk obstetric populations, women carrying multiples and adolescents carrying singletons, evaluating differences, if present, and identifying predictors of placental content.

METHODS

Placental tissue was collected from adolescents carrying singletons and adults carrying multiples. Elemental content was analyzed using inductively coupled plasma-mass spectrometry (ICP-MS). Multivariate regression and factor analyses were used.

RESULTS

With the exception of Au and Pt, almost all placentae contained quantifiable concentrations of each element analyzed. All placentae contained the essential elements Ca, Fe, Mg, Se and Zn, which clustered together onto the same factor. Most elements were higher in placentae from women carrying multiples. Differences in placental content disappeared after adjusting for maternal age. Rare earth elements (REEs) clustered together and remained higher in the multiples even after adjusting for maternal age.

CONCLUSION

Human placentae contain a wide range of elements, including REEs. Ranges differed considerably between cohorts. Elements with similar chemical properties, like REEs or nutritionally essential elements, clustered together. Maternal age, and therefore longer environmental exposure, was significantly associated with elevated element concentrations in the placenta. Placental concentrations of several metals that are known to be nutritionally essential (e.g., Fe, Ca, Mg, and Zn) did not differ significantly between cohorts, suggesting tight regulation, whereas concentrations of environmental contaminants differed significantly between groups, even after adjusting for maternal age.

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.

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.

Embryonic-only arsenic exposure in killifish (Fundulus heteroclitus) reduces growth and alters muscle IGF levels one year later

Arsenic is a contaminant of drinking water and crops in many parts of the world. Epidemiological studies have shown that arsenic exposure is linked to decreased birth weight, weight gain, and proper skeletal muscle function. The goal of this study was to use killifish (Fundulus heteroclitus) as a model to determine the long-term effects of embryonic-only arsenic exposure on muscle growth and the insulin-like growth factor (IGF) pathway. Killifish embryos were exposed to 0, 50, 200 or 800ppb As^III from fertilization until hatching. Juvenile fish were reared in clean water and muscle samples were collected at 16, 28, 40 and 52 weeks of age. There were significant reductions in condition factors, ranging from 12 to 17%, in the fish exposed to arsenic at 16, 28 and 40 weeks of age. However, by 52 weeks, no significant changes in condition factors were seen. Alterations in IGF-1R and IGF-1 levels were assessed as a potential mechanism by which growth was reduced. While there no changes in hepatic IGF-1 transcripts, skeletal muscle cells can also produce their own IGF-1 and/or alter IGF-1 receptor levels to help enhance growth. After a 200 and 800ppb embryonic exposure, fish grown in clean water for 16 weeks had IGF-1R transcripts that were 2.8-fold and 2-fold greater, respectively, than unexposed fish. Through 40 weeks of age, IGF1-R remained elevated in the 200ppb and 800ppb embryonic exposure groups by 1.8-3.9-fold, while at 52 weeks of age, IGF-1R levels were still significantly increased in the 800ppb exposure group. Skeletal muscle IGF-1 transcripts were also significantly increased by 1.9-5.1 fold through the 52 weeks of grow-out in clean by water in the 800ppb embryonic exposure group. Based on these results, embryonic arsenic exposure has long-term effects in that it reduces growth and increases both IGF-1 and IGF-1R levels in skeletal muscle even 1year after the exposure has ended.

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.

Effects of prenatal exposure to endocrine disruptors and toxic metals on the fetal epigenome

Exposure to environmental contaminants during pregnancy has been linked to adverse outcomes at birth and later in life. The link between prenatal exposures and latent health outcomes suggests that these exposures may result in long-term epigenetic reprogramming. Toxic metals and endocrine disruptors are two major classes of contaminants that are ubiquitously present in the environment and represent threats to human health. In this review, we present evidence that prenatal exposures to these contaminants result in fetal epigenomic changes, including altered global DNA methylation, gene-specific CpG methylation and microRNA expression. Importantly, these changes may have functional cellular consequences, impacting health outcomes later in life. Therefore, these epigenetic changes represent a critical mechanism that warrants further study.

Sexual epigenetic dimorphism in the human placenta: implications for susceptibility during the prenatal period

AIM

Sex-based differences in response to adverse prenatal environments and infant outcomes have been observed, yet the underlying mechanisms for this are unclear. The placental epigenome may be a driver of these differences.

METHODS

Placental DNA methylation was assessed at more than 480,000 CpG sites from male and female infants enrolled in the extremely low gestational age newborns cohort (ELGAN) and validated in a separate US-based cohort. The impact of gestational age on placental DNA methylation was further examined using the New Hampshire Birth Cohort Study for a total of n = 467 placentas.

RESULTS

A total of n = 2745 CpG sites, representing n = 587 genes, were identified as differentially methylated (p < 1 × 10^-7). The majority (n = 582 or 99%) of these were conserved among the New Hampshire Birth Cohort. The identified genes encode proteins related to immune function, growth/transcription factor signaling and transport across cell membranes.

CONCLUSION

These data highlight sex-dependent epigenetic patterning in the placenta and provide insight into differences in infant outcomes and responses to the perinatal environment.

Adverse associations between maternal and neonatal cadmium exposure and birth outcomes

Effects of low-level cadmium (Cd) exposure during early life on fetal growth remain unclear. Our aim was to evaluate whether Cd exposure in maternal urine and umbilical cord blood was associated with birth size parameters. A birth cohort study including 1073 mother-newborn pairs was conducted from 2009 to 2010 in an agricultural population in China. Cd concentrations were analyzed in both cord blood and maternal urine. Generalized linear models were performed to determine associations between maternal and neonatal exposure to Cd and birth indicators, including birth weight, length, head circumference and ponderal index. The median (25th to 75th percentile) value of Cd concentration in maternal urine and umbilical cord blood was 0.19 (0.08, 1.00) μg/L and 0.40 (<LOD~0.62) μg/L, respectively. After adjusting for potential confounders, Cd concentration in cord blood was significantly negatively associated with ponderal index at birth [β=-0.06g/cm³, 95% confidence interval (CI): -0.11, -0.02; p<0.01]. Considering sex difference, significant reduction in ponderal index was only observed in males (β=-0.06g/cm³, 95%CI: -0.11, -0.02; p<0.01), but not in females (β=-0.03g/cm³, 95%CI: -0.07, 0.01; p=0.18) (p for interaction term=0.24). Additionally, no significant associations were observed between maternal urinary Cd levels and birth outcomes. Our findings suggest that adverse effects of neonatal exposure to Cd on fetal growth are of considerable public health importance.

Placental biomarkers of PAH exposure and glutathione-S-transferase biotransformation enzymes in an obstetric population from Tijuana, Baja California, Mexico

Environmental exposures along the US-Mexico border have the potential to adversely affect the maternal-fetal environment. The purpose of this study was to assess placental biomarkers of environmental exposures in an obstetric population at the California-Baja California border in relation to detoxifying enzymes in the placenta and nutritional status. This study was conducted on consenting, full-term, obstetric patients (n=54), delivering in a hospital in Tijuana, Baja California (BC), Mexico. Placental polyaromatic hydrocarbon (PAH)-DNA adducts were measured in addition to placental glutathione-S-transferase (GST) activity and genotype, maternal serum folate, and maternal and umbilical cord blood lead and cadmium levels. A questionnaire was administered to the mothers to determine maternal occupation in a maquiladora, other exposures, and obstetric indicators. In univariate analysis, maternal serum folate levels were inversely correlated with total PAH-DNA adducts (rho=-0.375, p=0.007); adduct #1 (rho=-0.388, p=0.005); and adduct #3 (rho =-0.430, p=0.002). Maternal lead levels were significantly positively correlated with cord blood lead levels (rho=0.512, p<0.001). Cadmium levels were generally very low but significantly higher in mothers exposed to environmental tobacco smoke (ETS) (either at work or at home, n=10). In multivariate analysis, only maternal serum folate levels remained as a significant negative predictor of total DNA-PAH adducts levels in placenta. These findings affirm that placental tissue is a valuable and readily available source of human tissue for biomonitoring; and indicate that further study of the role of nutrition in detoxification and mitigation of environmental exposures in pregnant women is warranted.

Environmental and occupational exposure to cadmium in Iran: a systematic review

INTRODUCTION

Cadmium (Cd) is one of the heavy metals that have negative effects on human health. In Iran, there is no policy to regularly measure Cd in the general population. However, some studies have been performed on special groups and in different cities of Iran. This paper has reviewed these studies and human contamination levels in Iran.

METHOD AND MATERIALS

All accessible electronic information resources such as Scientific Information Database (SID), Magiran, IranMedex, PubMed, Web of Knowledge, Google Scholar and Science Direct were searched, with relevant phrases and their Persian translations. The search included all studies conducted in Iran and listed in the databases until March 15, 2016.

RESULTS

Eventually, 18 articles were selected from 25 retrieved articles. Cd was higher among industrial workers exposed to Cd. In the general population, Cd was higher among smokers and in people with environmental exposure from living in industrial areas.

CONCLUSION

Considering the high Cd contamination in the workers of industries, it seems to be necessary to do surveillance in this group through periodic regular check-ups and avoiding unnecessary exposure to Cd as much as possible. Also due to the high concentration of Cd in smokers, there should be more awareness of the damaging effects of smoking, especially among pregnant women, and more attention to local industries, especially those dealing with Cd, is necessary. These industries should be kept at a safe distance from residential areas.

Moderate Prenatal Cadmium Exposure and Adverse Birth Outcomes: a Role for Sex-Specific Differences?

BACKGROUND/AIM

Studies on the effects of moderate prenatal exposure to cadmium (Cd) on birth outcomes have been contradictory and it has been suggested that effects may be partly masked by sex-specific effects. Our aim was to examine the association of Cd exposure in a large group of pregnant women with birth outcomes in the whole group of participants and by sex.

METHODS

Pregnant women were enrolled in the Avon Longitudinal Study of Parents and Children (ALSPAC). Whole blood samples for singleton pregnancies with a live birth were analysed for Cd (n = 4191). Data collected on the infants included anthropometric variables and gestational age at delivery. Data were analysed using SPSS v18.

RESULTS

There were adverse associations of maternal blood Cd level with birthweight (unstandardized B coefficient -62.7 g, 95% CI -107.0, -18.4) and crown-heel length (-0.28 cm, 95% CI -0.48, -0.07) in adjusted regression models. On stratification by sex, maternal blood Cd level was adversely associated with birthweight (-87.1 g, 95% CI -144.8, -29.4), head circumference (-0.22 cm, 95% CI -0.39, -0.04), and crown-heel length (-0.44 cm, 95% CI -0.71, -0.18) in girls but not in boys in adjusted regression models.

CONCLUSION

In these pregnant women with moderate prenatal Cd exposure there evidence of adverse associations with birth anthropometry variables in the whole group. However, there was evidence of associations with anthropometric variables in girls that were not evident in boys. Sex-specific effects require further investigation in large cohorts as a possible contributor to the lack of associations generally found in mixed-sex studies.

The influence of maternal smoking on transferrin sialylation and fetal biometric parameters

OBJECTIVES

Transferrin is a glycosylated protein responsible for transporting iron, an essential metal responsible for proper fetal development. Tobacco is a heavily used xenobiotic having a negative impact on the human body and pregnancy outcomes. Aims of this study was to examine the influence of tobacco smoking on transferrin sialic acid residues and their connection with fetal biometric parameters in women with iron-deficiency.

METHODS

The study involved 173 samples from pregnant women, smokers and non-smokers, iron deficient and not. Transferrin sialylation was determined by capillary electrophoresis. The cadmium (Cd) level was measured by atomic absorption and the sialic acid concentration by the resorcinol method.

RESULTS

Women with iron deficiencies who smoked gave birth earlier than non-smoking, non-iron-deficient women. The Cd level, but not the cotinine level, was positively correlated with transferrin sialylation in the blood of iron-deficient women who smoked; 3-, 4-, 5- and 6-sialoTf correlated negatively with fetal biometric parameters in the same group.

CONCLUSION

It has been shown the relationship between Cd from tobacco smoking and fetal biometric parameters observed only in the iron deficient group suggests an additive effect of these two factors, and indicate that mothers with anemia may be more susceptible to Cd toxicity and disturbed fetal development.

Relation between in Utero Arsenic Exposure and Birth Outcomes in a Cohort of Mothers and Their Newborns from New Hampshire

BACKGROUND

Studies suggest that arsenic exposure influences birth outcomes; however, findings are mixed.

OBJECTIVE

We assessed in utero arsenic exposure in relation to birth outcomes and whether maternal prepregnancy weight and infant sex modified the associations.

METHODS

Among 706 mother-infant pairs exposed to low levels of arsenic through drinking water and diet, we assessed in utero arsenic exposure using maternal second-trimester urinary arsenic, maternal prepregnancy weight through self-report, and birth outcomes from medical records.

RESULTS

Median (interquartile range) of total urinary arsenic [tAs; inorganic arsenic (iAs) + monomethylarsonic acid (MMA) + dimethylarsinic acid (DMA)] was 3.4 μg/L (1.7-6.0). In adjusted linear models, each doubling of tAs was associated with a 0.10-cm decrease (95% CI: -0.19, -0.01) in head circumference. Results were similar for MMA and DMA. Ln(tAs) and ln(DMA) were positively associated with birth length in infant males only; among males, each doubling of tAs was associated with a 0.28-cm increase (95% CI: 0.09, 0.46) in birth length (pinteraction = 0.04). Results were similar for DMA. Additionally, arsenic exposure was inversely related to ponderal index, and associations differed by maternal weight. Each ln(tAs) doubling of tAs was associated with a 0.55-kg/m3 lower (95% CI: -0.82, -0.28, p < 0.001) ponderal index for infants of overweight/obese, but not normal-weight, mothers (pinteraction < 0.01). Finally, there was a significant interaction between maternal weight status, infant sex, and arsenic exposure on birth weight (pinteraction = 0.03). In girls born of overweight/obese mothers, each doubling of tAs was associated with a 62.9-g decrease (95% CI: -111.6, -14.2) in birth weight, though the association was null in the other strata.

CONCLUSIONS

Low-level arsenic exposure may affect fetal growth, and the associations may be modified by maternal weight status and infant sex.

CITATION

Gilbert-Diamond D, Emond JA, Baker ER, Korrick SA, Karagas MR. 2016. Relation between in utero arsenic exposure and birth outcomes in a cohort of mothers and their newborns from New Hampshire. Environ Health Perspect 124:1299-1307; http://dx.doi.org/10.1289/ehp.1510065.

Prenatal Arsenic Exposure and Birth Outcomes among a Population Residing near a Mining-Related Superfund Site

BACKGROUND

Limited epidemiologic data exist on prenatal arsenic exposure and fetal growth, particularly in the context of co-exposure to other toxic metals.

OBJECTIVE

We examined whether prenatal arsenic exposure predicts birth outcomes among a rural U.S. population, while adjusting for exposure to lead and manganese.

METHODS

We collected maternal and umbilical cord blood samples at delivery from 622 mother-infant pairs residing near a mining-related Superfund site in Northeast Oklahoma. Whole blood arsenic, lead, and manganese were measured using inductively coupled plasma mass spectrometry. We modeled associations between arsenic concentrations and birth weight, gestational age, head circumference, and birth weight for gestational age.

RESULTS

Median (25th-75th percentile) maternal and umbilical cord blood metal concentrations, respectively, were as follows: arsenic, 1.4 (1.0-2.3) and 2.4 (1.8-3.3) μg/L; lead, 0.6 (0.4-0.9) and 0.4 (0.3-0.6) μg/dL; manganese, 22.7 (18.8-29.3) and 41.7 (32.2-50.4) μg/L. We estimated negative associations between maternal blood arsenic concentrations and birth outcomes. In multivariable regression models adjusted for lead and manganese, an interquartile range increase in maternal blood arsenic was associated with -77.5 g (95% CI: -127.8, -27.3) birth weight, -0.13 weeks (95% CI: -0.27, 0.01) gestation, -0.22 cm (95% CI: -0.42, -0.03) head circumference, and -0.14 (95% CI: -0.24, -0.04) birth weight for gestational age z-score units. Interactions between arsenic concentrations and lead or manganese were not statistically significant.

CONCLUSIONS

In a population with environmental exposure levels similar to the U.S. general population, maternal blood arsenic was negatively associated with fetal growth. Given the potential for relatively common fetal and early childhood arsenic exposures, our finding that prenatal arsenic can adversely affect birth outcomes is of considerable public health importance.

CITATION

Claus Henn B, Ettinger AS, Hopkins MR, Jim R, Amarasiriwardena C, Christiani DC, Coull BA, Bellinger DC, Wright RO. 2016. Prenatal arsenic exposure and birth outcomes among a population residing near a mining-related Superfund site. Environ Health Perspect 124:1308-1315; http://dx.doi.org/10.1289/ehp.1510070.

Preconception Care: A New Standard of Care within Maternal Health Services

Emerging research suggests that much pediatric affliction has origins in the vulnerable phase of fetal development. Prenatal factors including deficiency of various nutrients and exposure to assorted toxicants are major etiological determinants of myriad obstetrical complications, pediatric chronic diseases, and perhaps some genetic mutations. With recent recognition that modifiable environmental determinants, rather than genetic predestination, are the etiological source of most chronic illness, modification of environmental factors prior to conception offers the possibility of precluding various mental and physical health conditions. Environmental and lifestyle modification through informed patient choice is possible but evidence confirms that, with little to no training in clinical nutrition, toxicology, or environmental exposures, most clinicians are ill-equipped to counsel patients about this important area. With the totality of available scientific evidence that now exists on the potential to modify disease-causing gestational determinants, failure to take necessary precautionary action may render members of the medical community collectively and individually culpable for preventable illness in children. We advocate for environmental health education of maternity health professionals and the widespread adoption and implementation of preconception care. This will necessitate the translation of emerging knowledge from recent research literature, to health professionals, to reproductive-aged women, and to society at large.

Maternal body burden of cadmium and offspring size at birth

Increasing evidence suggests an inverse association between cadmium (Cd) and size at birth, potentially greatest among female neonates. We evaluated whether greater maternal body burden of Cd is associated with reduced neonatal anthropometry (birthweight, birth length, head circumference, and ponderal index) and assessed whether these associations differ by infant sex. The analytic sample for the present study (n=396) was derived from a subcohort of 750 women randomly drawn from among all participants (N=4344) in the Omega Study, a prospective pregnancy cohort. Creatinine-corrected Cd in maternal clean-catch spot urine samples (U-Cd) was quantified by inductively coupled plasma mass spectrometry. Continuous log2-transformed Cd (log2-Cd) and U-Cd tertiles (low<0.29μg/g creatinine, middle 0.29-0.42μg/g creatinine, high≥0.43μg/g creatinine) were used in multivariable linear regression models. Females had reduced birth length with greater U-Cd tertile, whereas males birth length marginally increased [β(95% CI) females: low=reference, middle=-0.59cm (-1.37, 0.19), high=-0.83cm (-1.69, 0.02), p-trend=0.08; males: low=reference, middle=0.18cm (-0.59, 0.95), high=0.78cm (-0.04, 1.60), p-trend=0.07; p for interaction=0.03]. The log2-Cd by infant sex interaction was statistically significant for ponderal index [p=0.003; β(95% CI): female=0.25kg/m(3) (-0.20, 0.70); male=-0.63kg/m(3) (-1.01, -0.24)] and birth length [p<0.001; β(95% CI): female=-0.47cm (-0.74, -0.20), male=0.32cm (0.00, 0.65)]. Our findings suggest potential sex-specific reversal of Cd's associations on birth length and contribute to the evidence suggesting Cd impairs fetal growth.

Lead, mercury, and cadmium in umbilical cord serum and birth outcomes in Chinese fish consumers

Heavy metals such as lead (Pb), mercury (Hg), and cadmium (Cd) were detected in the islands of Yangtze River estuary and Hangzhou bay and their exposure caused potential health risk for the residents. To assess the exposure levels of Pb, Hg, and Cd, the umbilical cord serum samples were collected from 103 mother-newborn pairs as the noninvasive specimens. The association of the concentration of Pb, Hg, and Cd with the birth outcomes was evaluated. Pb, Hg, and Cd had high exposure levels with the median concentrations at 76.20 μg L(-1) [interquartile range (IQR): 44.71, 115.80], 21.94 μg L(-1) (IQR: 15.10, 27.64), and 6.36 μg L(-1) (IQR: 3.63, 13.34), respectively. A unit increase in the Pb umbilical cord serum concentration (μg L(-1)) was significantly associated with a 0.29 cm (95% CI: -0.50, -0.09) decrease in birth height and a 0.22 cm (95%CI: -0.44, 0.00) decrease in head circumference. The middle tertile Pb and Hg exposure levels were found significantly negative effects on birth outcomes compared with low tertile exposure levels. Exposure to Cd showed no apparent effect on birth outcomes. Our results suggested that Pb and Hg exposure has potential adverse effects on birth outcomes in Chinese fish consumers from Yangtze River outlet and Hangzhou bay estuary regions.

Newborns health in the Danube Region: Environment, biomonitoring, interventions and economic benefits in a large prospective birth cohort study

BACKGROUND

The EU strategy for the Danube Region addresses numerous challenges including environment, health and socioeconomic disparities. Many old environmental burdens and heavily polluted areas in Europe are located in the Danube Region, consisting of 14 countries, with over 100 million people. Estimating the burden of environmental exposures on early-life health is a growing research area in Europe which has major public health implications, but the data from the Danube Region are largely missing.

AIM

This review presents an inventory of current environmental challenges, related early-life health risks, and knowledge gaps in the Danube Region, based on publicly available databases, registers, and literature, as a rationale and incentive for a new integrated project. The review also proposes the concept for the project aiming to characterize in utero exposures to multiple environmental factors and estimate their effect on early-life health, evaluate economic impact, as well as identify interventions with a potential to harness social norms to reduce emissions, exposures and health risks in the Danube Region.

METHODS

Experts in environmental epidemiology, human biomonitoring and social science in collaboration with clinicians propose to establish a new large multi-center birth cohort of mother-child pairs from Danube countries, measure biomarkers of exposure and health in biological samples at birth, collect centrally measured climate, air and water pollution data, conduct pre- and postnatal surveys on lifestyle, indoor exposures, noise, occupation, socio-economic status, risk-averting behavior, and preferences; and undertake clinical examinations of children at and after birth. Birth cohort will include at least 2000 newborns per site, and a subset of at least 200 mother-child pairs per site for biomonitoring. Novel biomarkers of exposure, susceptibility, and effect will be applied, to gain better mechanistic insight. Effects of multiple environmental exposures on fetal and child growth, respiratory, allergic, immunologic, and neurodevelopmental health outcomes will be estimated. Parent's willingness to pay for reducing health risks in children will be elicited by survey, while values of cost-of-illness will be gathered from literature and national statistics. Effects of risk reducing interventions will be examined.

CONCLUSIONS

The proposed project would provide novel estimates of the burden of early childhood diseases attributable to environmental exposures and assess health impacts of different intervention scenarios in the Danube Region, in an integrated approach combining human biomonitoring, epidemiological and social science research.

The Epigenetic Effects of Prenatal Cadmium Exposure

Prenatal exposure to the highly toxic and common pollutant cadmium has been associated with adverse effects on child health and development. However, the underlying biological mechanisms of cadmium toxicity remain partially unsolved. Epigenetic disruption due to early cadmium exposure has gained attention as a plausible mode of action, since epigenetic signatures respond to environmental stimuli and the fetus undergoes drastic epigenomic rearrangements during embryogenesis. In the current review, we provide a critical examination of the literature addressing prenatal cadmium exposure and epigenetic effects in human, animal, and in vitro studies. We conducted a PubMed search and obtained eight recent studies addressing this topic, focusing almost exclusively on DNA methylation. These studies provide evidence that cadmium alters epigenetic signatures in the DNA of the placenta and of the newborns, and some studies indicated marked sexual differences for cadmium-related DNA methylation changes. Associations between early cadmium exposure and DNA methylation might reflect interference with de novo DNA methyltransferases. More studies, especially those including environmentally relevant doses, are needed to confirm the toxicoepigenomic effects of prenatal cadmium exposure and how that relates to the observed health effects of cadmium in childhood and later life.

Prenatal exposure to mixtures of xenoestrogens and genome-wide DNA methylation in human placenta

Background: In utero exposure to xenostrogens may modify the epigenome. We explored the association of prenatal exposure to mixtures of xenoestrogens and genome-wide placental DNA methylation. Materials & methods: Sex-specific associations between methylation changes in placental DNA by doubling the concentration of TEXB-alpha exposure were evaluated by robust multiple linear regression. Two CpG sites were selected for validation and replication in additional male born placentas. Results: No significant associations were found, although the top significant CpGs in boys were located in the LRPAP1, HAGH, PPARGC1B, KCNQ1 and KCNQ1DN genes, previously associated to birth weight, Type 2 diabetes, obesity or steroid hormone signaling. Neither technical validation nor biological replication of the results was found in boys for LRPAP and PPARGC1B. Conclusion: Some suggestive genes were differentially methylated in boys in relation to prenatal xenoestrogen exposure, but our initial findings could not be validated or replicated.

Low level arsenic contaminated water consumption and birth outcomes in Romania-An exploratory study

Women are exposed to drinking water with low arsenic concentrations (<10.0μg/L) worldwide, yet little work has been done to assess the risk. To begin to address this data gap, we conducted an exploratory study of birth outcomes in Timis County, Romania. We prospectively followed 122 women with singleton deliveries, for whom we constructed individual exposure indicators using self-reported water consumption weighted by arsenic measured in drinking water sources. There were no overall confounder-adjusted effects for arsenic exposure on birth outcomes. Yet, higher average arsenic (10μg/L) was associated with a -2.45 lower birth weight Z-score (P=0.021) and a -1.17 shorter birth length Z-score (P=0.029) among smokers. Higher average iAs (10μg/L) was also associated with smaller ponderal index in boys (P=0.023). Our results suggest smoking may potentiate an otherwise benign arsenic exposure. A larger, more definitive biomarker-based study is needed to investigate the potential risks in conjunction with smoking.

Effects of Environmental Exposures on Fetal and Childhood Growth Trajectories

Delayed fetal growth and adverse birth outcomes are some of the greatest public health threats to this generation of children worldwide because these conditions are major determinants of mortality, morbidity, and disability in infancy and childhood and are also associated with diseases in adult life. A number of studies have investigated the impacts of a range of environmental conditions during pregnancy (including air pollution, endocrine disruptors, persistent organic pollutants, heavy metals) on fetal and child development. The results, while provocative, have been largely inconsistent. This review summarizes up to date epidemiologic studies linking major environmental pollutants to fetal and child development and suggested future directions for further investigation.

Maternal exposure to arsenic and cadmium and the risk of congenital heart defects in offspring

Hair arsenic and cadmium from 339 women with congenital heart defect (CHD)-affected pregnancies (case women) and 333 women with normal live births (control women) in China were estimated using inductively coupled plasma mass spectrometry. The median levels of hair arsenic and cadmium in the case women were 98.30 (74.30-136.30)ng/g and 14.60 (8.30-32.50)ng/g, respectively, which were significantly higher than the levels in the control group (P<0.05). Arsenic concentrations ≥62.03ng/g were associated with increased risk for almost every CHD subtype, with a dose-response relationship. However, only the group with the highest cadmium levels (≥25.85ng/g) displayed an increased risk of CHDs (AOR 1.96; 95% CI 1.24-3.09), with a 2.81-fold increase found for the occurrence of conotruncal defects in their offspring. Furthermore, an interaction between arsenic and cadmium was observed. Our findings suggest that maternal exposure to arsenic and cadmium may be a significant risk factor for CHDs in offspring. Cadmium may have an enhancing effect on the association between arsenic and the risk of CHDs in offspring.

Effects of thirty elements on bone metabolism

The human skeleton, made of 206 bones, plays vital roles including supporting the body, protecting organs, enabling movement, and storing minerals. Bones are made of organic structures, intimately connected with an inorganic matrix produced by bone cells. Many elements are ubiquitous in our environment, and many impact bone metabolism. Most elements have antagonistic actions depending on concentration. Indeed, some elements are essential, others are deleterious, and many can be both. Several pathways mediate effects of element deficiencies or excesses on bone metabolism. This paper aims to identify all elements that impact bone health and explore the mechanisms by which they act. To date, this is the first time that the effects of thirty minerals on bone metabolism have been summarized.

Birth outcomes and background exposures to select elements, the Longitudinal Investigation of Fertility and the Environment (LIFE)

Evidence suggests that trace exposures to select elements may increase the risk for adverse birth outcomes. To investigate further, we used multiple regression to assess associations between preconception parental exposures to Pb, Cd, and total Hg in blood, and 21 elements in urine, with n=235 singleton birth outcomes, adjusted for confounders and partner's exposure. Earlier gestational age at delivery (GA) was associated with higher tertiles of urine maternal W (-1.22 days) and paternal U (-1.07 days), but GA was later for higher tertiles of maternal (+1.11 days) and paternal (+1.30 days) blood Hg. Additional analysis indicated shorter GA associated with higher paternal urine Ba, W, and U, and with higher maternal blood Pb for boys, but GA was longer in association with higher maternal urine Cr. Birth weight (BW) was lower for higher tertiles of paternal urine Cs (-237.85g), U (-187.34g), and Zn (-209.08g), and for higher continuous Cr (P=0.021). In contrast, BW was higher for higher tertiles of paternal urine As (+194.71g) and counterintuitively for maternal blood Cd (+178.52g). Birth length (BL) was shorter for higher tertiles of urine maternal W (-1.22cm) and paternal U (-1.10cm). Yet, higher tertiles of maternal (+1.11cm) and paternal (+1.30) blood Hg were associated with longer BL. Head circumference at delivery was lower for higher tertiles of paternal urine U (-0.83cm), and for higher continuous Mo in boys (-0.57cm). Overall, associations were most consistently indicated for GA and measures of birth size with urine W and U, and paternal exposures were more frequently associated than maternal. Though limited by several factors, ours is the largest multi-element investigation of prospective couple-level trace exposures and birth outcomes to date; the novel observations for W and U merit further investigation.

Geospatial association between adverse birth outcomes and arsenic in groundwater in New Hampshire, USA

There is increasing evidence of the role of arsenic in the etiology of adverse human reproductive outcomes. Because drinking water can be a major source of arsenic to pregnant women, the effect of arsenic exposure through drinking water on human birth may be revealed by a geospatial association between arsenic concentration in groundwater and birth problems, particularly in a region where private wells substantially account for water supply, like New Hampshire, USA. We calculated town-level rates of preterm birth and term low birth weight (term LBW) for New Hampshire, by using data for 1997-2009 stratified by maternal age. We smoothed the rates by using a locally weighted averaging method to increase the statistical stability. The town-level groundwater arsenic probability values are from three GIS data layers generated by the US Geological Survey: probability of local groundwater arsenic concentration >1 µg/L, probability >5 µg/L, and probability >10 µg/L. We calculated Pearson's correlation coefficients (r) between the reproductive outcomes (preterm birth and term LBW) and the arsenic probability values, at both state and county levels. For preterm birth, younger mothers (maternal age <20) have a statewide r = 0.70 between the rates smoothed with a threshold = 2,000 births and the town mean arsenic level based on the data of probability >10 µg/L; for older mothers, r = 0.19 when the smoothing threshold = 3,500; a majority of county level r values are positive based on the arsenic data of probability >10 µg/L. For term LBW, younger mothers (maternal age <25) have a statewide r = 0.44 between the rates smoothed with a threshold = 3,500 and town minimum arsenic concentration based on the data of probability >1 µg/L; for older mothers, r = 0.14 when the rates are smoothed with a threshold = 1,000 births and also adjusted by town median household income in 1999, and the arsenic values are the town minimum based on probability >10 µg/L. At the county level for younger mothers, positive r values prevail, but for older mothers, it is a mix. For both birth problems, the several most populous counties-with 60-80 % of the state's population and clustering at the southwest corner of the state-are largely consistent in having a positive r across different smoothing thresholds. We found evident spatial associations between the two adverse human reproductive outcomes and groundwater arsenic in New Hampshire, USA. However, the degree of associations and their sensitivity to different representations of arsenic level are variable. Generally, preterm birth has a stronger spatial association with groundwater arsenic than term LBW, suggesting an inconsistency in the impact of arsenic on the two reproductive outcomes. For both outcomes, younger maternal age has stronger spatial associations with groundwater arsenic.

Infant sex-specific placental cadmium and DNA methylation associations

BACKGROUND

Recent evidence suggests that maternal cadmium (Cd) burden and fetal growth associations may vary by fetal sex. However, mechanisms contributing to these differences are unknown.

OBJECTIVES

Among 24 maternal-infant pairs, we investigated infant sex-specific associations between placental Cd and placental genome-wide DNA methylation.

METHODS

We used ANOVA models to examine sex-stratified associations of placental Cd (dichotomized into high/low Cd using sex-specific Cd median cutoffs) with DNA methylation at each cytosine-phosphate-guanine site or region. Statistical significance was defined using a false discovery rate cutoff (<0.10).

RESULTS

Medians of placental Cd among females and males were 5 and 2 ng/g, respectively. Among females, three sites (near ADP-ribosylation factor-like 9 (ARL9), siah E3 ubiquitin protein ligase family member 3 (SIAH3), and heparin sulfate (glucosamine) 3-O-sulfotransferase 4 (HS3ST4) and one region on chromosome 7 (including carnitine O-octanoyltransferase (CROT) and TP5S target 1 (TP53TG1)) were hypomethylated in high Cd placentas. Among males, high placental Cd was associated with methylation of three sites, two (hypomethylated) near MDS1 and EVI1 complex locus (MECOM) and one (hypermethylated) near spalt-like transcription factor 1 (SALL1), and two regions (both hypomethylated, one on chromosome 3 including MECOM and another on chromosome 8 including rho guanine nucleotide exchange factor (GEF) 10 (ARHGEF10). Differentially methylated sites were at or close to transcription start sites of genes involved in cell damage response (SIAH3, HS3ST4, TP53TG1) in females and cell differentiation, angiogenesis and organ development (MECOM, SALL1) in males.

CONCLUSIONS

Our preliminary study supports infant sex-specific placental Cd-DNA methylation associations, possibly accounting for previously reported differences in Cd-fetal growth associations across fetal sex. Larger studies are needed to replicate and extend these findings. Such investigations may further our understanding of epigenetic mechanisms underlying maternal Cd burden with suboptimal fetal growth associations.

Preliminary analysis of in utero low-level arsenic exposure and fetal growth using biometric measurements extracted from fetal ultrasound reports

BACKGROUND

Early life exposure to arsenic is associated with decreased birth weight in highly exposed populations but little is known about effects of low-level arsenic exposure on growth in utero.

METHODS

Using a sample of 272 pregnancies from New Hampshire we obtained biometric measurements directly from fetal ultrasound reports commonly found in electronic medical records. We used information extraction methods to develop and validate an automated approach for mining biometric measurements from the text of clinical reports. As a preliminary analysis, we examined associations between in utero low-level arsenic exposure (as measured by maternal urinary arsenic concentration) and fetal growth measures (converted to Z-scores based on reference populations for estimated fetal weight, head, and other body measures) at approximately 18 weeks of gestation.

RESULTS

In a preliminary cross-sectional analysis of 223 out of 272 pregnancies, maternal urinary arsenic concentration (excluding arsenobetaine) was associated with a reduction in head circumference Z-score (Spearman correlation coefficient, rs = -0.08, p-value = 0.21) and a stronger association was observed among female fetuses at approximately 18 weeks of gestation (rs = - 0.21, p-value < 0.05). Although, associations were attenuated in adjusted analyses - among female fetuses a 1 μg/L increase in maternal urinary arsenic concentration was associated with a decrease of 0.047 (95% CI: -0.115, 0.021) in head circumference and 0.072 (95% CI: -0.151, 0.007) decrease in biparietal head diameter Z-score.

CONCLUSIONS

Our study demonstrates that useful data can be extracted directly from electronic medical records for epidemiologic research. We also found evidence that exposure to low-level arsenic may be associated with reduced head circumference in a sex dependent manner that warrants further investigation.

The developmental neurotoxicity of arsenic: cognitive and behavioral consequences of early life exposure

BACKGROUND

More than 200 million people worldwide are chronically exposed to arsenic. Arsenic is a known human carcinogen, and its carcinogenic and systemic toxicity have been extensively studied. By contrast, the developmental neurotoxicity of arsenic has been less well described. The aim of this review was to provide a comprehensive review of the developmental neurotoxicity of arsenic.

METHODS

We reviewed the published epidemiological and toxicological literature on the developmental neurotoxicity of arsenic.

RESULTS

Arsenic is able to gain access to the developing brain and cause neurotoxic effects. Animal models link prenatal and early postnatal exposure to reduction in brain weight, reductions in numbers of glia and neurons, and alterations in neurotransmitter systems. Animal and in vitro studies both suggest that oxidative stress may be a mechanism of arsenic neurotoxicity. Fifteen epidemiological studies indicate that early life exposure is associated with deficits in intelligence and memory. These effects may occur at levels of exposure below current safety guidelines, and some neurocognitive consequences may become manifest only later in life. Sex, concomitant exposures, and timing of exposure appear to modify the developmental neurotoxicity of arsenic. Four epidemiological studies failed to show behavioral outcomes of arsenic exposure.

CONCLUSIONS

The published literature indicates that arsenic is a human developmental neurotoxicant. Ongoing and future prospective birth cohort studies will allow more precise definition of the developmental consequences of arsenic exposure in early life.

Platelet hyperactivity, neurobehavioral symptoms and depression among Indian women chronically exposed to low level of arsenic

The prevalence of neurobehavioral symptoms (NBS) and depression has been investigated in premenopausal rural women of West Bengal, India enrolled from arsenic (As) endemic (groundwater As 11-50 μg/L; n = 342) and control areas (As level ≤ 10 μg/L; n = 312). The subjective symptoms questionnaire and Beck's 21-point depression inventory-II were used for the detection of NBS and depression, respectively. Platelet P-selectin expression was measured by flow cytometry, plasma neurotransmitter activity with high performance liquid chromatography and groundwater As level by atomic absorption spectroscopy. The As level in groundwater was 2.72 ± 1.18 μg/L in control and 28.3 ± 13.51 μg/L in endemic areas (p < 0.0001). Women residing in endemic areas demonstrated a higher prevalence of depressive symptoms (39.8 vs. 19.9%, p < 0.001) and anxiety (43.3 vs. 18.0% in control, p < 0.001), fatigue (68.4 vs. 23.4%, p < 0.0001), reduced sense of taste (15.8 vs. 4.5%, p<0.0001) and smell (14.9 vs. 5.8%, p < 0.001); burning sensation (36.8 vs. 5.4%, p < 0.0001) and tingling or numbness in the extremities (25.1 vs. 5.1%, p < 0.0001); and transient loss of memory (69.9 vs. 28.2%, p < 0.001). As-exposed women had 1.6-times more plasma epinephrine and norepinephrine (p < 0.05), 1.8-times higher level plasma serotonin with 28.9% lower intraplatelet serotonin (p < 0.05 for both), but their plasma dopamine level was not significantly different (p>0.05) from that of controls. Moreover, women from endemic areas had 2.3-times more P-selectin-expressing platelets in their circulation (p < 0.001). After controlling the potential confounders, chronic low level As (11-50 μg/L) exposure showed a positive association with the prevalence of neurobehavioral symptoms and depression among Indian women in their child-bearing age.

Infant toenails as a biomarker of in utero arsenic exposure

A growing body of evidence suggests that in utero and early-life exposure to arsenic may have detrimental effects on children, even at the low to moderate levels common in the United States and elsewhere. In a sample of 170 mother-infant pairs from New Hampshire, we determined infant exposure to in utero arsenic by evaluating infant toenails as a biomarker using inductively coupled plasma mass spectrometry. Infant toenail arsenic concentration correlated with maternal postpartum toenail concentrations (Spearman's correlation coefficient 0.34). In adjusted linear models, a doubling of maternal toenail arsenic concentration was associated with a 53.8% increase in infant toenail arsenic concentration as compared with 20.4% for a doubling of maternal urine arsenic concentration. In a structural equation model, a doubling of the latent variable integrating maternal toenail and urine arsenic concentrations was associated with a 67.5% increase in infant toenail arsenic concentration. A similar correlation between infant and maternal postpartum toenail concentrations was observed in a validation cohort of 130 mother-infant pairs from Rhode Island. In utero exposure to arsenic occurs through maternal water and dietary sources, and infant toenails appear to be a reliable biomarker for estimating arsenic exposure during the critical window of gestation.

Maternal urinary iodine concentration up to 1.0 mg/L is positively associated with birth weight, length, and head circumference of male offspring

Adequate iodine status in early life is crucial for neurodevelopment. However, little is known about the effects of maternal iodine status during pregnancy on fetal growth. The present study investigated the potential impact of maternal iodine status during pregnancy on offspring birth size. This large prospective cohort study was nested in a Bangladeshi population-based randomized supplementation trial in pregnant women [MINIMat (Maternal and Infant Nutrition Interventions in Matlab)]. Urine samples obtained at 8 wk of gestation from 1617 women were analyzed for iodine and other elements, such as arsenic and cadmium, using inductively coupled plasma mass spectrometry. Anthropometric measurements at birth included weight, length, and head and chest circumference. Maternal urinary iodine concentrations (UICs) ranged from 0.020 to 10 mg/L, with a median of 0.30 mg/L. Below ∼1.0 mg/L, UIC was significantly positively associated with birth weight and length. Birth weight and length increased by 9.3 g (95% CI: 2.9, 16) and 0.042 cm (95% CI: 0.0066, 0.076), respectively, for each 0.1-mg/L increase in maternal UIC. No associations were observed between UIC and head or chest circumference. When we stratified the analyses by newborn sex, the positive associations between maternal UIC (<1 mg/L) and measurements of size at birth were restricted to boys, with no evidence in girls. Among boys, the mean weight, length, and head circumference increased by 70 g (P = 0.019), 0.41 cm (P = 0.013), and 0.28 cm (P = 0.031) for every 0.5-mg/L increase in maternal UIC. Maternal iodine status was positively associated with weight, length, and head circumference in boys up to ∼1 mg/L, which is well above the recommended maximum concentration of 0.5 mg/L. The associations leveled off at UIC ≥ 1 mg/L. Our findings support previous conclusions that the advantages of correcting potential iodine deficiency outweigh the risks of excess exposure.

Arsenic exposure in early pregnancy alters genome-wide DNA methylation in cord blood, particularly in boys

Early-life inorganic arsenic exposure influences not only child health and development but also health in later life. The adverse effects of arsenic may be mediated by epigenetic mechanisms, as there are indications that arsenic causes altered DNA methylation of cancer-related genes. The objective was to assess effects of arsenic on genome-wide DNA methylation in newborns. We studied 127 mothers and cord blood of their infants. Arsenic exposure in early and late pregnancy was assessed by concentrations of arsenic metabolites in maternal urine, measured by high performance liquid chromatography-inductively coupled plasma mass spectrometry. Genome-wide 5-methylcytosine methylation in mononuclear cells from cord blood was analyzed by Infinium HumanMethylation450K BeadChip. Urinary arsenic in early gestation was associated with cord blood DNA methylation (Kolmogorov-Smirnov test, P-value<10-15), with more pronounced effects in boys than in girls. In boys, 372 (74%) of the 500 top CpG sites showed lower methylation with increasing arsenic exposure (r S -values>-0.62), but in girls only 207 (41%) showed inverse correlation (r S -values>-0.54). Three CpG sites in boys (cg15255455, cg13659051 and cg17646418), but none in girls, were significantly correlated with arsenic after adjustment for multiple comparisons. The associations between arsenic and DNA methylation were robust in multivariable-adjusted linear regression models. Much weaker associations were observed with arsenic exposure in late compared with early gestation. Pathway analysis showed overrepresentation of affected cancer-related genes in boys, but not in girls. In conclusion, early prenatal arsenic exposure appears to decrease DNA methylation in boys. Associations between early exposure and DNA methylation might reflect interference with de novo DNA methylation.

Maternal arsenic exposure and birth outcomes: a comprehensive review of the epidemiologic literature focused on drinking water

Inorganic arsenic (iAs) is a human toxicant to which populations may be exposed through consumption of geogenically contaminated groundwater. A growing body of experimental literature corroborates the reproductive toxicity of iAs; however, the results of human studies are inconsistent. Therefore, we conducted a comprehensive review of epidemiologic studies focused on drinking water iAs exposure and birth outcomes to assess the evidence for causality and to make recommendations for future study. We reviewed 18 English language papers assessing birth weight, gestational age, and birth size. Thirteen of the studies were conducted among populations with frequent exposure to high-level groundwater iAs contamination (>10 μg/L) and five studies were conducted in areas without recognized contamination. Most studies comprised small samples and used cross-sectional designs, often with ecologic exposure assessment strategies, although several large prospective investigations and studies with individual-level measurements were also reported. We conclude that: (1) the epidemiologic evidence for an increased risk of low birth weight (<2500 g) is insufficient, although there exists limited evidence for birth weight decreases; (2) the evidence for increased preterm delivery is insufficient; and, (3) there exists minimal evidence for decreased birth size. In further investigation of birth weight and size, we recommend incorporation of individual susceptibility measures using appropriate biomarkers, with collection timed to windows of vulnerability and speciated arsenic analysis, as well as consideration of populations exposed primarily to drinking water iAs contamination <10 μg/L. Given the large potential public health impact, additional, high quality epidemiologic studies are necessary to more definitively assess the risk.

Arsenic exposure affects plasma insulin-like growth factor 1 (IGF-1) in children in rural Bangladesh

BACKGROUND

Exposure to inorganic arsenic (As) through drinking water during pregnancy is associated with lower birth size and child growth. The aim of the study was to assess the effects of As exposure on child growth parameters to evaluate causal associations.

METHODOLOGY/FINDINGS

Children born in a longitudinal mother-child cohort in rural Bangladesh were studied at 4.5 years (n=640) as well as at birth (n=134). Exposure to arsenic was assessed by concurrent and prenatal (maternal) urinary concentrations of arsenic metabolites (U-As). Associations with plasma concentrations of insulin-like growth factor 1 (IGF-1), calcium (Ca), vitamin D (Vit-D), bone-specific alkaline phosphatase (B-ALP), intact parathyroid hormone (iPTH), and phosphate (PO4) were evaluated by linear regression analysis, adjusted for socioeconomic factor, parity and child sex. Child U-As (per 10 µg/L) was significantly inversely associated with concurrent plasma IGF-1 (β=-0.27; 95% confidence interval: -0.50, -0.0042) at 4.5 years. The effect was more obvious in girls (β=-0.29; -0.59, 0.021) than in boys, and particularly in girls with adequate height (β=-0.491; -0.97, -0.02) or weight (β=-0.47; 0.97, 0.01). Maternal U-As was inversely associated with child IGF-1 at birth (r=-0.254, P=0.003), but not at 4.5 years. There was a tendency of positive association between U-As and plasma PO4 in stunted boys (β=0.27; 0.089, 0.46). When stratified by % monomethylarsonic acid (MMA, arsenic metabolite) (median split at 9.7%), a much stronger inverse association between U-As and IGF-1 in the girls (β=-0.41; -0.77, -0.03) was obtained above the median split.

CONCLUSION

The results suggest that As-related growth impairment in children is mediated, at least partly, through suppressed IGF-1 levels.

Sex-specific effects of early life cadmium exposure on DNA methylation and implications for birth weight

Dietary cadmium exposure was recently found to alter DNA methylation in adults, but data on effects early in life are lacking. Our objective was to evaluate associations between prenatal cadmium exposure, DNA methylation and birth weight. In total 127 mother-child pairs from rural Bangladesh were studied. For comparison, we included 56 children at 4.5 y. Cadmium concentrations in mothers’ blood (gestational week 14) and children’s urine were measured by ICPMS. Global DNA methylation was analyzed by Infinium HumanMethylation450K BeadChip in cord blood and children’s blood. Maternal cadmium exposure was associated with cord blood DNA methylation (p-value < 10^–16). The association was markedly sex-specific. In boys, 96% of the top 500 CpG sites showed positive correlations (r_S-values > 0.50), whereas most associations in girls were inverse; only 29% were positive (r_S > 0.45). In girls we found overrepresentation of methylation changes in genes associated with organ development, morphology and mineralization of bone, whereas changes in boys were found in cell death-related genes. Several individual CpG sites that were positively associated with cadmium were inversely correlated with birth weight, although none statistically significant after correction for multiple comparisons. The associations were, however, fairly robust in multivariable-adjusted linear regression models. We identified CpG sites that were significantly associated with cadmium exposure in both newborns and 4.5-y-old children. In conclusion, cadmium exposure in early life appears to alter DNA methylation differently in girls and boys. This is consistent with previous findings of sex-specific cadmium toxicity. Cadmium-related changes in methylation were also related to lower birth weight.