Effect of low-level prenatal mercury exposure on neonate neurobehavioral development in China

From farm to table: assessing the status and health risk assessment of heavy metal pollution in rice in Henan Province

Introduction

In recent years, industrial and agricultural advancements in Henan Province have increased heavy metal contamination in rice, raising public concerns. The aim of this study was to investigate the contamination levels of five heavy metals, cadmium (Cd), chromium (Cr), lead (Pb), mercury (Hg), and inorganic arsenic (As), in rice from Henan Province and to assess potential health risks.

Methods

A total of 6,632 rice samples were collected from 18 regions between 2020 and 2022. The samples were analyzed for Cd, Cr, Pb, Hg, and As using inductively coupled plasma mass spectrometry (ICP-MS). Detection rates were compared using the chi-square test, and health risks were assessed for the three populations (adults, children and toddlers) according to USEPA guidelines.

Results

The results of the study showed that As had the highest detection rate of 99.59%, followed by Cd (27.69%), Cr (22.57%), Pb (2.25%) and Hg (1.95%). Cd levels were significantly higher in urban areas (30.42%) than rural areas (23.13%) (P < 0.001). The detection rate of Cd was higher in the southern region compared to other regions, while the detection rate of Cr in the eastern region was the highest among all regions. The health risk assessment showed that the Hazard Quotient (HQ) for inorganic As exceeded 1. However, children and toddlers were at relatively higher risk of exposure to As compared to adults.

Conclusion

This study revealed the current status of heavy metal contamination in rice in Henan, particularly highlighting the presence of As as a significant health hazard for children and toddlers. Consequently, it is recommended that the relevant authorities should strengthen the monitoring and control of food safety in order to effectively protect public health.

Hair and cord blood element levels and their relationship with air pollution, dietary intake, gestational diabetes mellitus, and infant neurodevelopment

BACKGROUND & AIMS

Exposure to a range of elements, air pollution, and specific dietary components in pregnancy has variously been associated with gestational diabetes mellitus (GDM) risk or infant neurodevelopmental problems. We measured a range of pregnancy exposures in maternal hair and/or infant cord serum and tested their relationship to GDM and infant neurodevelopment.

METHODS

A total of 843 pregnant women (GDM = 224, Non-GDM = 619) were selected from the Complex Lipids in Mothers and Babies cohort study. Forty-eight elements in hair and cord serum were quantified using inductively coupled plasma-mass spectrometry analysis. Binary logistic regression was used to estimate the associations between hair element concentrations and GDM risk, while multiple linear regression was performed to analyze the relationship between hair/cord serum elements and air pollutants, diet exposures, and Bayley Scales of infant neurodevelopment at 12 months of age.

RESULTS

After adjusting for maternal age, BMI, and primiparity, we observed that fourteen elements in maternal hair were associated with a significantly increased risk of GDM, particularly Ta (OR = 9.49, 95% CI: 6.71, 13.42), Re (OR = 5.21, 95% CI: 3.84, 7.07), and Se (OR = 5.37, 95% CI: 3.48, 8.28). In the adjusted linear regression model, three elements (Rb, Er, and Tm) in maternal hair and infant cord serum were negatively associated with Mental Development Index scores. For dietary exposures, elements were positively associated with noodles (Nb), sweetened beverages (Rb), poultry (Cs), oils and condiments (Ca), and other seafood (Gd). In addition, air pollutants PM2.5 (LUR) and PM10 were negatively associated with Ta and Re in maternal hair.

CONCLUSIONS

Our findings highlight the potential influence of maternal element exposure on GDM risk and infant neurodevelopment. We identified links between levels of these elements in both maternal hair and infant cord serum related to air pollutants and dietary factors.

Effects of low doses of methylmercury (MeHg) exposure on definitive endoderm cell differentiation in human embryonic stem cells

Fetal development is one of the most sensitive windows to methylmercury (MeHg) toxicity. Laboratory and epidemiological studies have shown a dose-response relationship between fetal MeHg exposure and neuro performance in different life stages from infants to adults. In addition, MeHg exposure has been reported to be associated with disorders in endoderm-derived organs, such as morphological changes in liver cells and pancreatic cell dysfunctions. However, the mechanisms of the effects of MeHg on non-neuronal organs or systems, especially during the early development of endoderm-derived organs, remain unclear. Here we determined the effects of low concentrations of MeHg exposure during the differentiation of definitive endoderm (DE) cells from human embryonic stem cells (hESCs). hESCs were exposed to MeHg (0, 10, 100, and 200 nM) that covers the range of Hg concentrations typically found in human maternal blood during DE cell induction. Transcriptomic analysis showed that sub-lethal doses of MeHg exposure could alter global gene expression patterns during hESC to DE cell differentiation, leading to increased expression of endodermal genes/proteins and the over-promotion of endodermal fate, mainly through disrupting calcium homeostasis and generating ROS. Bioinformatic analysis results suggested that MeHg exerts its developmental toxicity mainly by disrupting ribosome biogenesis during early cell lineage differentiation. This disruption could lead to aberrant growth or dysfunctions of the developing endoderm-derived organs, and it may be the underlying mechanism for the observed congenital diseases later in life. Based on the results, we proposed an adverse outcome pathway for the effects of MeHg exposure during human embryonic stem cells to definitive endoderm differentiation.

Association of mercury exposure with the serum high-sensitivity C-reactive protein level in Korean adults

Although there is evidence that mercury (Hg) exposure may be a potential risk factor for cardiovascular disease (CVD), few nationwide epidemiological researches have analyzed the association between blood Hg concentration and serum high-sensitivity C-reactive protein (hs-CRP) level as a biomarker of CVD. The present population-based national study was performed with data from the 2016-2017 National Health and Nutrition Examination Survey. In the total sample of 3,773 adults aged ≥20 years, the serum hs-CRP concentrations were 1.03 mg/L among participants in the lowest quartile of blood Hg level and 1.18 mg/L among those in highest quartile. The trend for the prevalence of a risky (>1.0 mg/L) hs-CRP level (moderate risk and high risk) was significantly related to an increased quartile blood Hg concentration. After adjustment for confounders, participants with the highest quartiles of blood Hg had increased odds of a risky (>1.0 mg/L) hs-CRP level (adjusted odds ratio = 1.34; 95% confidence interval, 1.02-1.77) compared with those with the lowest quartile of blood Hg. These findings demonstrate that a high blood Hg level increases the concentration of serum hs-CRP, a sensitive marker of chronic low-grade inflammation, and imply that the increased body burden associated with high blood Hg is a potential risk factor in the development of many inflammatory diseases, including CVD.

Free Cortisol Mediates Associations of Maternal Urinary Heavy Metals with Neonatal Anthropometric Measures: A Cross-Sectional Study

Prenatal exposure to heavy metals is known to be associated with adverse birth outcomes and oxidative stress biomarkers. In this study, we examined whether maternal free cortisol or 8-Hydroxy-2-Deoxyguanosine (8-OHdG) could mediate associations between maternal heavy metal exposure and birth outcomes. A total of 182 healthy pregnant women were recruited. Heavy metals (including Pb, Hg, and Cd), free-cortisol, and 8-OHdG were analyzed in urine at delivery. Birth outcomes including birth weight, length, Ponderal index, and head circumference were measured. To examine associations of maternal urinary heavy metals with biomarkers and birth outcomes, generalized linear models were employed. Birth length was positively associated with Pb (β = 0.78, 95% CI: 0.09−1.46) and Hg (β = 0.84, 95% CI: 0.23−1.45) (both p < 0.05). The Ponderal index, a measure of a newborn’s leanness, was negatively associated with maternal urinary Pb (β = −0.23, 95% CI: −0.46−−0.07) and Hg (β = −0.26, 95% CI: −0.44−−0.08) (both p < 0.05). No association between maternal Cd and birth outcomes was observed. Most heavy metals showed positive associations with free cortisol and 8-OHdG. Free cortisol was identified as a mediator underlying the observed relationship between Hg and birth length or Ponderal index. This study observed adverse birth outcomes from maternal exposures to Pb and Hg. Increased free cortisol related to Hg exposure was suggested as a possible causal pathway from Hg exposure to birth outcomes such as the Ponderal index.

Prenatal Mercury Exposure and Neurodevelopment up to the Age of 5 Years: A Systematic Review

Neurodevelopmental delays can interfere with children’s engagement with the world and further development, and may have negative consequences into adulthood. Mercury is highly toxic and may negatively influence neurodevelopment because it can freely cross the placenta and accumulate in the fetal brain. We searched four publication databases (Embase, PsycINFO, PubMed/MEDLINE, Scopus) for studies examining the relationship between early life mercury exposure and scores on neurodevelopmental performance measures in children aged 0 to 5 years old. Study quality was assessed using the National Institutes of Health (NIH) Quality Assessment Tool. Thirty-two prospective studies were included in the review. Neurodevelopmental performance was measured using 23 different scales, most commonly the Bayley Scales of Infant and Toddler Development (BSID). In most cases, the evidence for an association between mercury and neurodevelopment was weak. There did not appear to be exceptions for particular childhood ages, outcome scales, or mercury levels. The small number of results to the contrary were more likely to be studies which did not meet our high-quality criteria, and could be a consequence of multiple testing, selection bias, or incomplete confounder adjustment. Based on current evidence, dietary mercury exposure during pregnancy is unlikely to be a risk factor for low neurodevelopmental functioning in early childhood.

Effects of low-level mercury exposure on brain-derived neurotrophic factor in preschool children

OBJECTIVES

Mercury (Hg), a ubiquitous heavy metal, could affect the neurodevelopment of the children, however, these associations are still equivocal. Brain derived neurotrophic factor (BDNF) plays an essential role in the central nervous system development in children. This study aimed to investigate the effects of low-level mercury exposure on serum BDNF levels and the influence of sex and dietary intake on these relationships in children.

METHODS

In this cross-sectional study, a total of 541 pre-school children were recruited, the blood mercury concentrations and serum BDNF levels were measured. The background information on demographic characteristics and dietary habits of the children was collected through questionnaires. Multivariable linear models after adjustment for potential confounders were used to evaluate the associations between mercury exposure and levels of BDNF in children.

RESULTS

The GMs of blood mercury concentrations and serum BDNF levels were 1.06 μg/L, 20.4 ng/mL, respectively. A significant positive association between blood mercury concentrations and serum BDNF levels was found. After stratification by sex, the blood mercury concentrations in children were positive associated with serum BDNF levels in girls but not in boys. However, these associations were attenuated when we further adjusted the children's dietary intake variables.

CONCLUSIONS

Our findings suggest that low-levels of mercury exposure may have sex-specific effects on BDNF levels in young children and that dietary intake may be potential confounders in these relationships. However, further studies are warranted to investigate the role of BDNF in the effects of mercury on neurodevelopment.

Factors Associated with High Mercury Levels in Women and Girls from The Mojana Region, Colombia, 2013-2015

Women are primarily exposed to mercury through the consumption of fish contaminated by gold mining activities. The main systems affected are the central nervous and renal systems, although effects on the reproductive system have also been found. Objective: To explore the relationship between mercury levels in women and their possible sources of contamination. A cross-sectional study was conducted from 2013 to 2015 with women residing in 11 municipalities in La Mojana, Colombia, using non-random sampling. Standardized instruments were used to identify sociodemographic characteristics, mercury use, mining-related activities, water and fish consumption, and other factors. Blood, urine, and hair samples were taken to quantify mercury levels. A logistic regression model was used to identify factors associated with elevated mercury values in the participants’ samples. A total of 428 women were included, with an average age of 36.7 ± 16.7 years, 3.3% of whom were pregnant at the time of the survey and 8.4% of whom were exposed occupationally. High levels of mercury were present in 62.8% of the women, in any one of the three samples processed. Those exposed occupationally and environmentally had similar values (p = 0.821). Frequency of fish consumption and source of drinking water were associated with higher levels of mercury (p < 0.05).

Epigenetic modifications associated with in utero exposure to endocrine disrupting chemicals BPA, DDT and Pb

Endocrine disrupting chemicals (EDCs) are xenobiotics which adversely modify the hormone system. The endocrine system is most vulnerable to assaults by endocrine disruptors during the prenatal and early development window, and effects may persist into adulthood and across generations. The prenatal stage is a period of vulnerability to environmental chemicals because the epigenome is usually reprogrammed during this period. Bisphenol A (BPA), lead (Pb), and dichlorodiphenyltrichloroethane (DDT) were chosen for critical review because they have become serious public health concerns globally, especially in Africa where they are widely used without any regulation. In this review, we introduce EDCs and describe the various modes of action of EDCs and the importance of the prenatal and developmental windows to EDC exposure. We give a brief overview of epigenetics and describe the various epigenetic mechanisms: DNA methylation, histone modifications and non-coding RNAs, and how each of them affects gene expression. We then summarize findings from previous studies on the effects of prenatal exposure to the endocrine disruptors BPA, Pb and DDT on each of the previously described epigenetic mechanisms. We also discuss how the epigenetic alterations caused by these EDCs may be related to disease processes.

Prenatal and Early Postnatal Exposure to Total Mercury and Methylmercury from Low Maternal Fish Consumption

The aim of this study was to investigate the influence of low fish consumption on prenatal and early postnatal exposure to mercury species. The samples of umbilical cord blood and maternal milk as well as interviewer-administered questionnaires were collected from 142 Slovak mother-child pairs. The mean total mercury (THg) concentrations in cord blood and milk were 0.949 μg/L and 0.376 μg/kg, respectively. The mean methylmercury (MeHg) concentration in cord blood was 0.504 μg/L. Fish eaters had significantly higher cord blood MeHg concentrations than non-fish eaters (p = 0.030); no difference was found in milk or cord blood THg concentrations. The bivariate analysis showed a positive correlation between cord blood MeHg and consumption of sea fish and shellfish (r_s = 0.320, p < 0.001); after adjustment for the potential confounders, the association was weakened (β = 0.173, p = 0.059). Nevertheless, the decision tree method showed sea fish and shellfish consumption to be the best predictor of cord blood MeHg. Furthermore, a negative association was found between THg concentrations in maternal milk and freshwater fish consumption (β = - 0.193, p = 0.017), which might indicate a beneficial effect of freshwater fish consumption. The results suggest there is a need for future research to investigate the benefits versus the adverse effects of low maternal fish consumption on child development.

Prenatal polycyclic aromatic hydrocarbons metabolites, cord blood telomere length, and neonatal neurobehavioral development

BACKGROUND

Prenatal exposure to polycyclic aromatic hydrocarbon (PAH) is a potential risk factor for child neurobehavioral development. Telomere length (TL) has important implications for health over the life course.

OBJECTIVE

In this study, we aimed to investigate whether prenatal urinary PAH metabolites were associated with adverse neonatal neurobehavioral development and altered cord blood TL and to explore whether the change of TL was a predictor of neonatal neurobehavioral development.

METHOD

We enrolled 283 nonsmoking pregnant women in Taiyuan city. Eleven PAH metabolites were measured in maternal urine samples. TL in cord blood was measured by real time quantitative polymerase chain reaction. Neonatal behavioral neurological assessment (NBNA) tests were conducted when the infants were three days old. Multiple linear regression models were used to analyze the associations of maternal urinary PAH metabolites with NBNA scores and cord blood TL, and restricted cubic spline models were further used to examine the shapes of dose-response relationships. A mediation analysis was also conducted.

RESULT

We observed dose-response associations of maternal urinary 2-hydroxyfluorene (2-OHFlu) and 2-hydroxyphenanthrene (2-OH Phe) with decreased active tone scores, sum of NBNA scores, and cord blood TL (P for trend<0.05). Each 1 unit increase in urinary levels of Ln (2-OH Flu) or Ln (2-OH Phe) was associated with a 0.092 or 0.135 decrease in the active tone scores and a 0.174 or 0.199 decrease in the sum of NBNA scores. Mediation analysis showed TL could explained 21.74% of the effect of sum of NBNA scores change related to prenatal exposure to 2-OH Phe (P for mediator = 0.047).

CONCLUSION

Our data indicates maternal urinary specific PAH metabolites are inversely associated with neonatal neurobehavioral development and cord blood TL. TL mediates the associations of 2-OH Phe with neonatal neurobehavioral development and partly explains the effect of 2-OH Phe on neonatal neurobehavioral development.

Relation of prenatal low-level mercury exposure with early child neurobehavioral development and exploration of the effects of sex and DHA on it

BACKGROUND

The extent to which low-level, in utero mercury exposure affects child neurobehavioral development during early childhood has been inconclusive. In addition, the effects of sex and docosahexaenoic acid (DHA) on these relationships remain unclear and controversial.

OBJECTIVES

This study aimed to explore the associations between prenatal low-level mercury exposure and child neurobehavioral development during the neonatal and toddler periods and to examine the potential confounding or interactive effects of sex and DHA status on these relationships.

METHODS

This longitudinal study included 286 mother-child pairs in Shanghai, China, whose cord blood samples were analyzed for total mercury, DHA, other nutrients and coexposure contaminants possibly due to maternal consumption of seafood. Children's neurobehavioral development was assessed with the Neonatal Behavioral Neurological Assessment (NBNA) three days after birth and the Bayley Scales of Infant and Toddler Development, Third Edition (BSID-III) at 18 months of age.

RESULTS

Cord blood mercury concentration, with geometric mean of 2.00 μg/l, was related to poorer NBNA performance but unrelated to BSID-III scores with adjustment for DHA and other covariates. Cord serum DHA was positively associated with motor development assessed by the BSID-III. The interaction was found between mercury and DHA on the NBNA score, and the inverse relation of cord blood mercury with NBNA was significant only among the children with lower DHA levels (<45.54 μg/ml). Additional adjustment for DHA didn't change the associations between cord blood mercury and neurodevelopmental outcomes substantially. The mercury by sex interaction for language of BSID-III was borderline significant.

CONCLUSIONS

Our research provides initial evidence for the negative effects of prenatal low-level mercury exposure on neonates' neurobehavioral development. Prenatal DHA status may modify the relationship between cord blood mercury level and neonatal neurobehavioral development, but the confounding effects of DHA were not observed. Further studies are warranted before the causality of the observed associations can be determined.

Heavy Metals in Indigenous Preparations Used for Sex Selection During Pregnancy in India

Indigenous preparations (IPs) have evoked a considerable interest in alleviating infections and chronic diseases and improving wellbeing. While such formulations have been a part of traditional practice in several countries and many have been reviewed scientifically for their claims, several of them until date remain to be investigated. A class of IPs for sex selection by Indian pregnant women exists with an aim of begetting a male offspring. In view of the leads obtained from our previous studies on detrimental effects of the newborn, for instance stillbirths and congenital malformations, we attempted to investigate the samples for heavy metal toxicity. Three samples were chosen following phytochemical analysis and reproductive toxicity of such preparations under in vivo conditions. The selected samples were examined for heavy metals-lead, cadmium, arsenic, and mercury using Microwave-assisted atomic absorption spectroscopy. The upper limit level of lead, mercury, and cadmium was found to be 18.56, 0.11, and 0.84 mg/kg respectively whereas arsenic was not detected. The levels of lead and mercury were found to be manifolds high in the IP samples that were primarily contributed by its constituents. The results of our study indicate the potential risk conferred upon, to both the mother and fetus on account of high levels of lead, mercury, and cadmium.

Lead and Mercury Levels in Preterm Infants Before and After Blood Transfusions

Very low birth weight (VLBW) infants usually receive packed red blood cell unit (pRBC) transfusions. Heavy metal transfer via pRBCs is not widely discussed before. This study aimed to determine pre-/post-transfusion erythrocyte lead and mercury levels in infants and to correlate these levels to heavy metal concentrations in pRBCs. VLBW infants (n = 80), needing pRBC transfusion for the first time, were enrolled. Erythrocyte heavy metal levels were determined in pre-/post-transfusion blood samples and also in pRBC units. Mean lead and mercury levels in the pRBCs were found to be 16.3 ± 10.8 and 3.75 ± 3.23 μg/L, respectively. Of the infants, 69.7% received lead above reference dose. Erythrocyte lead levels increased significantly after transfusions (10.6 ± 10.3 vs. 13 ± 8.5, p < 0.05) with significant correlated to amount of lead within pRBCs (r = 0.28). Mean pre-/post-transfusion erythrocyte mercury levels were 3.28 ± 3.08 and 3.5 ± 2.83 μg/L, respectively (p > 0.05). There was a significant correlation between mean difference of mercury levels after transfusion and amount of mercury delivered by pRBCs (r = 0.28). Infants can be subject to high levels of lead and mercury through pRBC transfusions.

Mercury Materno-fetal Burden and Its Nutritional Impact

BACKGROUND:

Mercury exists worldwide in food, water and air throwing its health hazards on all body systems.

AIM:

To show the influence of the presence of mercury in pregnant mothers’ blood on its level in the umbilical cord blood; and to display the relationship between the different foodstuff on the mercury levels in pregnant mothers’ and umbilical cord blood.

PATIENTS AND METHODS:

This cross-sectional study was conducted on randomly chosen 113 pregnant mothers at the time of labour and on their newborns. Full history, sociodemographic data and food frequency questionnaire for dietary assessment were recorded. The Maternal and neonatal anthropometric measurements together with the Apgar scoring were also measured. Serum mercury levels in both mothers’ and umbilical cord blood were measured using the Inductively Coupled Plasma Mass Spectrometry (ICP-MS).

RESULTS:

A high percentage of mothers (82.3%) were exposed to passive smoking. There was a statistically significant positive correlation between the maternal and fetal umbilical cord blood mercury levels (p = 0.002). There was an insignificant negative correlation between the maternal blood and fetal umbilical cord blood mercury levels on one side and each of the different foodstuff on the other side (fish, vegetables, fruits and proteins, for example, meat and legumes). An insignificant positive correlation was found between dairy products and of the maternal blood and umbilical cord blood mercury levels.

CONCLUSION:

The fetal umbilical cord blood mercury levels correlate positively with the maternal blood mercury. The different foodstuff can influence the maternal and umbilical cord blood mercury levels whether by increase or decrease. Strict measures should be taken to decrease environmental mercury contamination with attention to pregnant mothers.

Determine Multiple Elements Simultaneously in the Sera of Umbilical Cord Blood Samples-a Very Simple Method

Analyzing the concentrations of heavy metals in the sera of umbilical cord blood samples can provide useful information about prenatal exposure to environmental agents. An analytical method based on ICP-MS to simultaneously determine multiple elements in umbilical cord blood samples was developed for assessing the in utero exposure to metallic and metalloid elements. The method only required as little as 100 μL of serum diluted 1:25 for direct analysis. Matrix-matched protocol was used to eliminate mass matrix interference and kinetic energy discrimination mode was used to eliminate the polyatomic ion interference. The assay was completed on average within 4 min with the detection limits ranging from 0.0002 to 44.4 μg/L for all the targeted elements. The detection rates for most of elements were 100 % other than cadmium (Cd), lead (Pb), and mercury (Hg). The testing results of the certified reference materials were ideal. The method is simple and sensitive, so it is suitable for the monitoring of large quantities of samples.

Scientific foundations of fish-consumption advice for pregnant women: Epidemiological evidence, benefit-risk modeling, and an integrated approach

BACKGROUND

Pregnant women need fish consumption advice that increases seafood intake and simultaneously reduces methylmercury (MeHg) exposure. Two disciplines, epidemiology and benefit-risk modeling, can support such advice. Some current models suggest that fish consumption during pregnancy has only net beneficial effects. In contrast, many recent epidemiological studies have associated adverse effects on cognitive development with ordinary fish intake and MeHg doses routinely encountered by up to one in six US women of childbearing age. Proposed federal fish-consumption advice is based solely on a benefit-risk model. A more complete assessment integrating both types of evidence is needed.

OBJECTIVES AND METHODS

The goal of this paper is to use a model to rank seafood items by their relative benefits and risks, producing consumer seafood choice recommendations that are also consistent with epidemiological observations. Recent epidemiological studies and benefit-risk models are reviewed, and model results are compared with one another and with epidemiological observations to identify commonalities that support inter-calibration.

RESULTS AND CONCLUSIONS

Both approaches quantify MeHg doses at which harm slightly exceeds benefit. A model from the US Food and Drug Administration (FDA) predicts adverse effects at fish intakes containing, on average, more than 16 times the the US Reference Dose (RfD) for MeHg. Epidemiological results indicate that the RfD itself approximates a minimal adverse dose. This conceptual similarity allows FDA's model to be calibrated with the epidemiological results to generate fish intake recommendations that both the model and the epidemiology suggest should have substantially positive public health impacts.

Is there a relationship between tea intake and maternal whole blood heavy metal concentrations?

The aim of this analysis was to examine the association between tea intake during pregnancy and maternal and infant metal exposures. Data from the Maternal-Infant Research on Environmental Chemicals (MIREC) Study, a pan-Canadian pregnancy cohort, were used. All participants with a gestational age of ⩾20 weeks (n=1954) with available biomarkers were included. Geometric means (GMs) for lead, arsenic, mercury, cadmium and manganese in maternal (first and third trimesters) and cord blood, as well as speciated arsenic in maternal urine in the first trimester, were calculated for participants who drank regular, green or herbal tea and for those who did not. Differences between groups were examined using chi-square tests. Adjusted least squares geometric means (LSGMs) were estimated by tea intake, controlling for factors such as country of birth, coffee intake and maternal smoking. Concentrations of all metals were above the limits of detection in most participants in the first trimester: lead (GM): 0.62 μg/dl), mercury (GM: 2.99 nmol/l); cadmium (GM 1.93 nmol/l), arsenic (GM 9.75 nmol/l) and manganese (GM 160.1 nmol/l). Adjusted LSGMs for lead in the first trimester were higher for tea drinkers than for those who were non-tea drinkers (LSGM 0.65 μg/dl, 95%CI: 0.62, 0.69 and 0.61 μg/dl, 95%CI: 0.59, 0.62), and there was evidence of a dose-response relationship for green and herbal tea. Those who consumed herbal tea in the third trimester had significantly higher third trimester maternal and cord blood lead concentrations than non-herbal tea drinkers. This study provides evidence of an association between blood lead concentrations and green or herbal tea consumption. However, the GM blood lead concentrations of the highest tea consumers were still less than 1 μg/dl and within the normal range of blood lead concentrations in the Canadian population.

Exploring the associations between microRNA expression profiles and environmental pollutants in human placenta from the National Children's Study (NCS)

The placenta is the principal regulator of the in utero environment, and disruptions to this environment can result in adverse offspring health outcomes. To better characterize the impact of in utero perturbations, we assessed the influence of known environmental pollutants on the expression of microRNA (miRNA) in placental samples collected from the National Children's Study (NCS) Vanguard birth cohort. This study analyzed the expression of 654 miRNAs in 110 term placentas. Environmental pollutants measured in these placentas included dichlorodiphenyldichloroethylene (DDE), bisphenol A (BPA), polybrominated diphenyl ethers (PBDEs), polychlorinated biphenyls (PCBs), arsenic (As), mercury (Hg), lead (Pb), and cadmium (Cd). A moderated t-test was used to identify a panel of differentially expressed miRNAs, which were further analyzed using generalized linear models. We observed 112 miRNAs consistently expressed in >70% of the samples. Consistent with the literature, miRNAs located within the imprinted placenta-specific C19MC cluster, specifically mir-517a, mir-517c, mir-522, and mir-23a, are among the top expressed miRNA in our study. We observed a positive association between PBDE 209 and miR-188-5p and an inverse association between PBDE 99 and let-7c. Both PCBs and Cd were positively associated with miR-1537 expression level. In addition, multiple let-7 family members were downregulated with increasing levels of Hg and Pb. We did not observe DDE or BPA levels to be associated with placental miRNA expression. This is the first birth cohort study linking environmental pollutants and placental expression of miRNAs. Our results suggest that placental miRNA profiles may signal in utero exposures to environmental chemicals.

The critical fetal stage for maternal manganese exposure

Prenatal exposure and the health effects of that exposure have been intensively studied for a variety of environmental pollutants and trace elements. However, few studies have compared susceptibilities among the three trimesters of gestation. Manganese (Mn) is a naturally occurring and abundant trace element in the environment. Although the effects of Mn on animals are well documented, knowledge of the effects of Mn exposure on pregnant women and fetuses remains limited. A longitudinal study was conducted by collecting blood samples during all three trimesters, and Mn exposure was completely characterized during gestation. The aims of this study were to examine the effects of maternal Mn exposure on neonatal birth outcomes and to explore the critical stage of these effects. In total, 38, 76 and 76 samples were obtained from singleton pregnant women in their first, second and third trimesters, respectively. The cohort of pregnant women was selected at a medical center in northern Taiwan. Erythrocyte samples were collected during the first, second and third trimesters of gestation. Erythrocyte Mn concentrations were measured by inductively coupled plasma mass spectrometry. Neonatal birth outcomes were evaluated immediately after delivery. A multivariate regression model was used to determine the associations between maternal Mn levels in erythrocytes in each trimester and neonatal birth outcomes. The geometric mean concentrations of Mn were 2.93 μg/dL, 3.96 μg/dL and 4.41 μg/dL in the first, second and third trimesters, respectively. After adjusting for potential confounders, a consistently negative association was found between maternal Mn levels throughout the three trimesters and birth outcomes. Log-transformed Mn levels in maternal erythrocytes in the second trimester were significantly associated with neonatal birth weight, head and chest circumferences, respectively (β=-556.98 g, p=0.038; β=-1.87 cm, p=0.045; β=-2.74 cm, p=0.024). Despite the limited sample size in the first trimester, negative effects of maternal Mn levels on birth weight (β=-1108.95 g, p<0.01) and chest circumference (β=-4.40 cm, p=0.019) were also observed.