Cord Blood Mercury Concentrations Research Articles

The impact of prenatal mercury on neurobehavioral functioning longitudinally assessed from a young age to pre-adolescence in a Spanish birth cohort

The objective is to investigate the relation between cord blood mercury concentrations and child neurobehavioural functioning assessed longitudinally during childhood until pre-adolescence. MethodsThe study involves mothers and their offspring engaged in the Spanish INMA birth cohort (n = 1147). Total mercury (THg) was determined in cord blood. Behavioural problems were assessed several times during childhood using the ADHD-DSM-IV at age 4, SDQ at ages 7 and 11, CPRS-R:S and the CBCL at ages 7, 9 and 11. Covariates were obtained through questionnaires during the whole period. Multivariate generalised negative binomial (MGNB) models or mixed-effects MGNB (for those tests with information at one or more time points, respectively) were used to investigate the relation between cord blood THg and the children's punctuations. Models were adjusted for prenatal fish intake. Effect modification by sex, prenatal and postnatal fish intake, prenatal fruit and vegetable intake, and maternal polychlorinated biphenyl concentrations (PCBs) was assessed by interaction terms. ResultsThe geometric mean ± standard deviation of cord blood THg was 8.22 ± 2.19 μg/L. Despite adjusting for fish consumption, our results did not show any statistically significant relationship between prenatal Hg and the children's performance on behavioural tests conducted between the ages of 4 and 11. Upon assessing the impact of various factors, we observed no statistically significant interaction. ConclusionDespite elevated prenatal THg exposure, no association was found with children's behavioural functioning assessed from early childhood to pre-adolescence. The nutrients in fish could offset the potential neurotoxic impact of Hg. Further birth cohort studies with longitudinal data are warranted.

Risk factors associated with developing anxiety in Inuit adolescents from Nunavik

This study aimed to examine the relation between anxiety among the at-risk population of Inuit adolescents and diverse developmental risk factors including exposure to environmental chemicals, a subject of concern in Nunavik. Anxiety was assessed in 89 Inuit participants (mean age = 18.4 years; range = 16.2–21.9) with the Screen for Child Anxiety Related Emotional Disorders (SCARED) and the State-Trait Anxiety Inventory (STAI). Potential risk factors for anxiety were documented at birth, 11 years of age and 18 years of age, including blood levels of chemicals (mercury, lead, PCBs) and nutrients, as well as age, sex, estimated IQ, drug and alcohol use, bullying, exposure to domestic violence, food insecurity, crowding and socio-economic status. Results showed that participants scored high on both measures of anxiety, particularly the SCARED, for which the mean score was above the clinical threshold. Multiple regression results show that significant risk predictors obtained from the SCARED scores were female sex (β = 0.32), higher current blood mercury concentration (β = 0.26), food insecurity (β = 0.26) and bullying experiences in the last year (β = 0.21). The significant predictors for the STAI trait anxiety were food insecurity (β = 0.25) and lower estimated IQ (β = −0.31), whereas food insecurity (β = 0.21), lower blood levels of vitamin E (β = −0.25) and higher cord blood mercury concentrations (β = 0.25) were found for STAI situational anxiety. Further regression analyses suggested that the adolescent-related variables were the most important risk factors. Our findings show that Inuit adolescents are at risk for anxiety via multiple contributing factors, particularly current exposure to mercury, food insecurity and female sex.

The Association Between Mercury Exposure and Atopic Dermatitis in Early Childhood: A Mothers and Children's Environmental Health Study.

Atopic dermatitis is a chronic and relapsing inflammatory skin disease. Although mercury has been suggested as a risk factor, the underlying mechanism and the relationship between mercury and atopic dermatitis remains unclear. The objective of the present study was to investigate the relationship between mercury exposure and the presence of atopic dermatitis in early childhood. This study is part of the prospective Mothers and Children's Environmental Health cohort study. A total of 1,751 pregnant women were enrolled in Mothers and Children's Environmental Health. After delivery, children were followed up. Blood samples were collected and mothers were asked about the presence of atopic dermatitis in their children via a questionnaire at 6, 12, 24, 36, and 60 months of age. After excluding participants who did not meet the inclusion criteria, a total of 1,061 mother-children pairs were included in the analysis. The geometric mean of mercury concentrations in cord blood was 5.1 µg/L. In adjusted models, cord blood mercury exposure (odds ratio [OR] = 1.1; 95% confidence interval [CI] = 1.0, 1.2 at 12-24 months) and postnatal mercury exposure (OR = 1.2; 95% CI = 1.0, 1.5 at 24-36 months, OR = 1.4; 95% CI = 1.1, 1.8 at 48-60 months) were associated with the presence of atopic dermatitis in children. Postnatal mercury exposure at 24 months of age increases the risk of atopic dermatitis in children.

Very low-level prenatal mercury exposure and behaviors in children: the HOME Study

BackgroundMercury is toxic to the developing brain, but the lowest concentration associated with the development of behavior problems is unclear. The purpose of this study was to examine the association between very low-level mercury exposure during fetal development and behavior problems in children.MethodsWe used data from 389 mothers and children in a prospective pregnancy and birth cohort study. We defined mean prenatal mercury concentration as the mean of total whole blood mercury concentrations in maternal samples collected at 16- and 26-weeks of gestation, delivery, and neonatal cord blood samples. We assessed parent-reported child behavior up to five times from two to 8 years of age using the Behavioral Assessment System for Children (BASC-2). At 8 years of age, we assessed self-reported child anxiety using the Spence Children’s Anxiety Scale (SCAS). We used multiple linear mixed models and linear regression models to estimate the association between mean prenatal mercury concentrations and child behavior and anxiety, respectively.ResultsThe median prenatal total blood mercury concentrations was 0.67 μg/L. Overall, we did not find statistically significant associations between mean prenatal mercury concentrations and behavior problems scores, but a 2-fold increase in mercury concentrations at 16-weeks gestation was associated with 0.83 point (95% CI: 0.05, 1.62) higher BASC-2 anxiety scores. Maternal and cord blood mercury concentrations at delivery were associated with parent-reported anxiety at 8 years.ConclusionWe found limited evidence of an association between very-low level prenatal mercury exposure and behaviors in children, with an exception of anxiety.

Assessment of Mercury in Diagnostic Biomaterials of Different Population Groups in Urban Areas of the Moscow Region

The results of a survey of different population groups in urban areas of the Moscow Region (industry workers, residents of areas with increased anthropogenic load of mercury and conditionally pristine areas, cohorts of pregnant women and children) to assess the contents of mercury in samples of various diagnostic biomaterials taken during the course of research are presented. Mercury concentrations in venous and umbilical cord blood, urine, hair, and nails were determined by means of instrumental neutron activation analysis and cold vapor atomic absorption spectrometry. Peculiarities of selection, transportation, storage, and preparation for analysis of samples of hair, nails, urine and umbilical venous blood are described. The determined concentrations of mercury in the studied diagnostic biomaterials are compared with normal and thresholds values. Although increased mercury concentrations were observed in some cases, no significant exposure of mercury was evident in general in the study towns. A positive correlation between the degree of consumption of seafood during pregnancy and a high content of mercury in the analyzed diagnostic biomaterials was shown.

Prenatal Exposure to Polychlorinated Biphenyls and Mercury Are Associated with Insulin-Like Growth Factor 1 and Thyroid-Stimulating Hormone in Cord Plasma

Impact on maternal endocrine system during pregnancy may also affect growth and development of a fetus. Certain toxic elements and polychlorinated biphenyls (PCBs) are known to disturbe human endocrine system. In our previous study, we showed that birth weight were affected by prenatal PCBs and methylmercury exposure. In this study, we used the data from the Tohoku Study of Child Development in Japan. The objective of the study was to evaluate the effect of prenatal exposure to methylmercury, arsenic, cadmium, lead, and PCBs on insulin-like growth factor 1 (IGF-1) and thyroid related hormones (TSH, T3, freeT3, T4 and freeT4) in cord blood. Those factros are considered to be associated with fetal growth. Elements except for mercury were analyzed by an inductivity coupled plasma mass spectrometry. Mercury levels were measured using a cold vapor atomic absorption spectrometer. IGF-1 and insulin-like growth factor binding protein 1 (IGFBP1) were detemined by an enzyme-linked immunosorbent assay (ELISA). Thyroid related hormones were assessed by an electrochemiluminescence immunoassay. The data were examined by Pearson’s correlation and multiple regression analyses. The IGF-1 in cord plasma was negatively associated with PCB concentrations in cord blood, especially with tri-, tetra-, penta-, hexa- and hepta-chlorobiphenyls. Cord plasma free T4 was negatively associated with mercury concentrations in cord blood. This study indicated PCBs and mercury could affect birth weight through altering the IGF1 and T4 mechanism. Further studies are necessary to investigate the effect of decrease in IGF-1 and thyroid hormones on birth weight.

Gestational diabetes and offspring birth size at elevated environmental pollutant exposures

BackgroundGestational diabetes mellitus (GDM) is associated with increased availability of glucose and macronutrients in fetal circulation and macrosomia. Therefore, the role of GDM in the association between metabolism-disrupting chemicals and birth size deserves attention. ObjectiveWe examined whether GDM may mediate or modify the associations between maternal environmental pollutant exposures and offspring birth size measures. MethodsWe analyzed 604 Faroese pregnant women and their offsprings born in 1997–2000. Maternal pregnancy serum concentrations of organochlorine compounds (OCs: polychlorinated biphenyl (PCB) congeners and dichlorodiphenyldichloroethylene (DDE)), and five perfluoroalkyl substances (PFASs), and hair and cord blood mercury concentrations were measured. We used regression (single-pollutants) and structural equation models (SEMs) (multiple-pollutant analyses using latent constructs of OCs, PFASs and mercury) to estimate the associations with GDM and birth size measures, accounting for mediation and/or effect modification by GDM. ResultsSerum-DDE and hair-mercury concentrations were associated with GDM (adjusted OR per concentration doubling: 1.29; 95% CI: 0.94, 1.77 for DDE, and 0.79; 95% CI: 0.62, 0.99 for mercury), but in multiple pollutant-adjusted SEMs only a positive association between OC exposure and GDM remained significant (change in GDM odds per OC doubling: 0.45; 95% CI: 0.05, 0.86). PCB and overall OC exposure were positively associated with head circumference (SEM; mean change per OC doubling: 0.13cm; 95% CI, 0.01. 0.25). Overall PFAS exposure was inversely associated with birth weight (SEM; mean change per PFAS doubling: −169g; 95% CI: −359, 21), and for many single-PFASs we found a pattern of inverse associations with birth weight and head circumference in boys, and positive or null associations in girls. None of the environmental pollutants was associated with offspring length. GDM neither modified nor mediated the associations with birth size measures. ConclusionsWe found associations with GDM and offspring birth size to be specific to the environmental pollutant or pollutant group. Associations with birth size measures appear to be independent of GDM occurrence.

Associations of prenatal and early childhood mercury exposure with autistic behaviors at 5 years of age: The Mothers and Children's Environmental Health (MOCEH) study

BackgroundAlthough mercury is an established neurotoxin, only few longitudinal studies have investigated the association between prenatal and early childhood mercury exposure and autistic behaviors. MethodsWe conducted a longitudinal cohort study using an ongoing prospective birth cohort initiated in 2006, wherein blood mercury levels were measured at early and late pregnancy; in cord blood; and at 2 and 3years of age. We analyzed 458 mother-child pairs. Autistic behaviors were assessed using the Social Responsiveness Scale (SRS) at 5years of age. Both continuous SRS T-scores and T-scores dichotomized by a score of ≥60 or <60 were used as outcomes. ResultsThe geometric mean of mercury concentrations in cord blood was 5.52μg/L. In adjusted models, a doubling of blood mercury levels at late pregnancy (β=1.84, 95% confidence interval [CI]: 0.39, 3.29), in cord blood (β=2.24, 95% CI: 0.22, 4.27), and at 2years (β=2.12, 95% CI: 0.54, 3.70) and 3years (β=2.80, 95% CI: 0.89, 4.72) of age was positively associated with the SRS T-scores. When the SRS T-scores were dichotomized, we observed positive associations with mercury levels at late pregnancy (relative risk [RR]=1.31, 95% CI: 1.08, 1.60) and in cord blood (RR=1.28, 95% CI: 1.01, 1.63). ConclusionWe found that blood mercury levels at late pregnancy and early childhood were associated with more autistic behaviors in children at 5years of age. Further study on the long-term effects of mercury exposure is recommended.

CYP3A genes and the association between prenatal methylmercury exposure and neurodevelopment

BackgroundResults on the association between prenatal exposure to methylmercury (MeHg) and child neuropsychological development are heterogeneous. Underlying genetic differences across study populations could contribute to this varied response to MeHg. Studies in Drosophila have identified the cytochrome p450 3A (CYP3A) family as candidate MeHg susceptibility genes. ObjectivesWe evaluated whether genetic variation in CYP3A genes influences the association between prenatal exposure to MeHg and child neuropsychological development. MethodsThe study population included 2639 children from three birth cohort studies: two subcohorts in Seychelles (SCDS) (n=1160, 20 and 30months of age, studied during the years 2001–2012), two subcohorts from Spain (INMA) (n=625, 14months of age, 2003–2009), and two subcohorts from Italy and Greece (PHIME) (n=854, 18months of age, 2006–2011). Total mercury, as a surrogate of MeHg, was analyzed in maternal hair and/or cord blood samples. Neuropsychological development was evaluated using Bayley Scales of Infant Development (BSID). Three functional polymorphisms in the CYP3A family were analyzed: rs2257401 (CYP3A7), rs776746 (CYP3A5), and rs2740574 (CYP3A4). ResultsThere was no association between CYP3A polymorphisms and cord mercury concentrations. The scores for the BSID mental scale improved with increasing cord blood mercury concentrations for carriers of the most active alleles (β[95% CI]:=2.9[1.53,4.27] for CYP3A7 rs2257401 GG+GC, 2.51[1.04,3.98] for CYP3A5 rs776746 AA+AG and 2.31[0.12,4.50] for CYP3A4 rs2740574 GG+AG). This association was near the null for CYP3A7 CC, CYP3A5 GG and CYP3A4 AA genotypes. The interaction between the CYP3A genes and total mercury was significant (p<0.05) in European cohorts only. ConclusionsOur results suggest that the polymorphisms in CYP3A genes may modify the response to dietary MeHg exposure during early life development.

Influence of seafood and vitamin supplementation on maternal and umbilical cord blood mercury concentration

BackgroundThe purpose of this study was to examine the influence of maternal seafood consumption and vitamin supplementation during pregnancy on maternal and umbilical cord blood mercury (Hg) concentration. MethodsIn this study of 145 healthy pregnant women (mean age 28.1±5.2 years), we administered questionnaires, collected paired maternal/umbilical cord blood samples, and measured the anthropometrics of newborns. Blood Hg concentration was assayed by inductively coupled plasma-mass spectrometry. ResultsSixty-one of these women (42.1%) used vitamins >3 times/wk prenatally. Seventy-eight of our study participants (61.9%) reported eating higher amounts of seafood during pregnancy. We found a strong correlation (r=0.76, p<0.001) between Hg levels in the paired maternal/umbilical cord blood samples. Mothers with high seafood consumption had a 2.91-fold greater risk (adjusted odds ratio 2.91, 95% confidence interval: 1.04–8.15, p=0.042) of high Hg levels (>5.8 μg/L). However, mothers whose prenatal vitamin intake was >3 times/wk were found to have low Hg levels (≤5.8 μg/L) (adjusted odds ratio 0.06, 95% confidence interval: 0.01–049, p=0.008). ConclusionHigh seafood consumption was an independent risk factor for high maternal Hg level, while vitamin supplementation was a protective factor. Further study is needed to investigate the specific effect of vitamins on Hg level.

Aerobic Fitness and Neurocognitive Function Scores in Young Faroese Adults and Potential Modification by Prenatal Methylmercury Exposure.

Background:Exposure to methylmercury was shown to decrease neural stem cell populations, whereas aerobic fitness has beneficial effects on the adult brain that relies on improved neurogenesis in the hippocampus.Objectives:We examined the association between aerobic fitness and neurocognitive outcomes at young adult age, along with the potential moderating effect of prenatal exposure to methylmercury.Methods:At age 22 years, 262 members of a Faroese birth cohort, established in 1986–1987, underwent a graded exercise test of aerobic fitness to measure maximal oxygen uptake (VO2Max). Their prenatal methylmercury exposure had been assessed from the mercury concentration in cord blood. We estimated cross-sectional associations between VO2Max and multiple measures of neurocognitive function. In addition, we compared groups with low and high prenatal methylmercury exposure.Results:A 1 standard deviation (SD) increase in VO2Max was associated with better scores on short-term memory and cognitive processing speed by 0.21 SD (95% CI: –0.04, 0.46) and 0.28 SD (95% CI: 0.02, 0.54), respectively. In the group with lower prenatal methylmercury exposure, a 1 SD increase in VO2Max was associated with increased scores on cognitive processing speed by 0.45 SD (95% CI: 0.08, 0.81) and with a slightly lesser benefit in short-term memory. No such association was observed in the group with high prenatal methylmercury exposure.Conclusions:Higher aerobic capacity was associated with better performance in short-term memory and processing speed. However, prenatal methylmercury exposure seemed to attenuate these positive associations.Citation:Oulhote Y, Debes F, Vestergaard S, Weihe P, Grandjean P. 2017. Aerobic fitness and neurocognitive function scores in young Faroese adults and potential modification by prenatal methylmercury exposure. Environ Health Perspect 125:677–683; http://dx.doi.org/10.1289/EHP274

Assessing a New Method for Measuring Fetal Exposure to Mercury: Newborn Bloodspots.

Background: Measuring mercury in newborn bloodspots to determine fetal exposures is a novel methodology with many advantages. Questions remain, however, about its reliability as an estimate of newborn exposure to mercury. Methods: We studied mercury concentrations in paired bloodspots and cord blood from a convenience sample of 48 Minnesota women and infants. Results: The limit of detection for bloodspots was higher than for cord blood (0.7 and 0.3 μg/L in bloodspots and cord blood, respectively) with the result that mercury was detected in only 38% of newborn bloodspots compared to 62% of cord blood samples. The geometric mean mercury concentration in cord blood was 0.6 μg/L. Mercury concentrations were almost uniformly lower in bloodspots than in cord blood (mean ratio (±SD) = 0.85 ± 0.4), their mean value was significantly less than that for the cord blood (p = 0.02), and the two methods were highly correlated (r = 0.82). Conclusion: These preliminary findings indicate that newborn bloodspot mercury measurements have utility; however, until bloodspot analyses are more sensitive, they are likely to underestimate in utero exposure.

Mercury concentration in maternal serum, cord blood, and placenta in patients with amalgam dental fillings: effects on fetal biometric measurements

Aim: We aimed to determine the extent to which mercury is transmitted from the mother to fetus via the umbilical cord in patients with amalgam dental fillings, and its effect on fetal biometric measurements.Methods: Twenty-eight patients as the study group with amalgam fillings, and 32 of them as the control group were included in this prospective case–control study. The mercury levels were measured in the maternal and cord venous sera, and the placental samples. Two groups were compared in terms of these and the fetal/neonatal biometric measurements.Results: In the study group, the maternal and umbilical cord mercury levels were found to be significantly higher than those from the control group (p = 0.006 and p = 0.010, respectively). These high levels did not affect the fetal biometric measurements.Conclusions: The presence of high serum mercury levels in pregnant women with amalgam fillings is important, and warrants further long-term studies in order to investigate the fetal neurological effects as well.

Maternal Consumption of Seafood in Pregnancy and Child Neuropsychological Development: A Longitudinal Study Based on a Population With High Consumption Levels.

Seafood consumption during pregnancy is thought to be beneficial for child neuropsychological development, but to our knowledge no large cohort studies with high fatty fish consumption have analyzed the association by seafood subtype. We evaluated 1,892 and 1,589 mother-child pairs at the ages of 14 months and 5 years, respectively, in a population-based Spanish birth cohort established during 2004-2008. Bayley and McCarthy scales and the Childhood Asperger Syndrome Test were used to assess neuropsychological development. Results from multivariate linear regression models were adjusted for sociodemographic characteristics and further adjusted for umbilical cord blood mercury or long-chain polyunsaturated fatty acid concentrations. Overall, consumption of seafood above the recommended limit of 340 g/week was associated with 10-g/week increments in neuropsychological scores. By subtype, in addition to lean fish, consumption of large fatty fish showed a positive association; offspring of persons within the highest quantile (>238 g/week) had an adjusted increase of 2.29 points in McCarthy general cognitive score (95% confidence interval: 0.42, 4.16). Similar findings were observed for the Childhood Asperger Syndrome Test. Beta coefficients diminished 15%-30% after adjustment for mercury or long-chain polyunsaturated fatty acid concentrations. Consumption of large fatty fish during pregnancy presents moderate child neuropsychological benefits, including improvements in cognitive functioning and some protection from autism-spectrum traits.

Impact of fetal and childhood mercury exposure on immune status in children

BackgroundMercury exposure have been shown to affect immune status in animals as reflected by cytokine expression. It is unclear whether low levels of exposure during fetal and/or childhood periods could impact on immune status in humans. ObjectivesTo test the hypothesis that fetal and childhood mercury exposure is associated with childhood cytokine profiles and to investigate whether childhood selenium levels interact with any of the associations found. MethodsChildren were recruited from a previously established birth cohort between the ages of 6–9 years for assessment and measurement of blood mercury, selenium and cytokine profile (interleukin (IL)-4, IL-6, IL-8, IL-10, IL-13 and TNF-alpha). Multivariable linear regression models were used to assess the adjusted association of cord blood mercury concentration and current mercury concentrations with levels of the cytokine levels. We tested whether the association with current mercury level varied by current selenium level and cord blood mercury level. ResultsIL-10 was negatively associated with current blood mercury concentration. The effect was greatest in cases with low cord blood mercury and low current selenium concentrations. None of the other cytokine levels were associated with either cord blood or current blood mercury concentrations, except that cord blood mercury was negatively associated with IL-6. ConclusionsChildhood mercury exposure was negatively associated with childhood IL-10 levels. It is postulated that while selenium is protective, low levels of fetal mercury exposure may increase the degree of this negative association during childhood. Further studies into the clinical significance of these findings are required.

Factors associated with total mercury concentrations in maternal blood, cord blood, and breast milk among pregnant women in Busan, Korea.

This study investigated the concentration of total mercury (THg) in maternal blood, cord blood, and breast milk, and its association with dietary factors. A total of 127 pregnant women in Busan, Korea were recruited. Maternal blood, cord blood, and breast milk were collected at 36 weeks of gestation, at delivery, and at one week after birth, respectively. Information about dietary habits and other factors were obtained from each subject. The mean THg concentrations in maternal blood, cord blood, and breast milk were 3.12±1.36 μg/L, 5.46±2.41 μg/L, and 0.91±2.08 μg/L, respectively. Positive correlations were found between log-transformed THg concentrations in maternal blood and cord blood (r=0.829, p<0.001), and between maternal blood and breast milk (r=0.296, p=0.001). Multiple linear regression analysis showed that the log-transformed concentration of THg in maternal blood was positively correlated with fish consumption (β=0.345, p<0.0001) and negatively correlated with bean consumption (β=-0.055, p=0.048). Fish consumption (β=0.482, p<0.0001) and maternal age (β=0.025, p=0.033) were positively associated with the concentration of THg in cord blood, while negative correlations were found for bean consumption (β=-0.134, p=0.027) and parity (β=-0.172, p=0.015). Beef consumption (β=0.031, p=0.007) was positively associated with log-transformed THg concentrations in breast milk, while negative correlations were found for bean consumption (β=-0.019, p=0.003) and maternal age (β=-0.083, p=0.004). Our study found that both the dietary and demographic factors differently affected to THg concentrations among samples of maternal blood, cord blood, and breast milk.

Cognitive deficits at age 22 years associated with prenatal exposure to methylmercury

Prenatal exposure to mercury has been associated with adverse effects on child neurodevelopment. The present study aims to determine the extent to which methylmercury-associated cognitive deficits persist into adult age. In a Faroese birth cohort originally formed in 1986–1987 (N = 1,022), prenatal methylmercury exposure was assessed in terms of the mercury concentration in cord blood and maternal hair. Clinical examinations of 847 cohort members at age 22 years were carried out in 2008–2009 using a panel of neuropsychological tests that reflected major functional domains. Subjects with neurological and psychiatric diagnoses were excluded from the data analysis, thus leaving 814 subjects. Multiple regression analysis included covariates previously identified for adjustment. Deficits in Boston Naming Test (BNT) and other tests of verbal performance were significantly associated with the cord-blood mercury concentration. Deficits were also present in all other tests applied, although most were not statistically significant. Structural equation models were developed to ascertain the possible differences in vulnerability of specific functional domains and the overall association with general intelligence. In models for individual domains, all of them showed negative associations, with crystallized intelligence being highly significant. A hierarchical model for general intelligence based on all domains again showed a highly significant negative association with the exposure, with an approximate deficit that corresponds to about 2.2 IQ points at a 10-fold increased prenatal methylmercury exposure. Thus, although the cognitive deficits observed were smaller than at examinations at younger ages, maternal diets with contaminated seafood were associated with adverse effects in this birth cohort at age 22 years. The deficits affected major domains of brain functions as well as general intelligence. Thus, prenatal exposure to this marine contaminant appears to cause permanent adverse effects on cognition.

Depressed height gain of children associated with intrauterine exposure to polycyclic aromatic hydrocarbons (PAH) and heavy metals: The cohort prospective study

Fetal exposure to environmental toxicants may program the development of children and have long-lasting health impacts. The study tested the hypothesis that depressed height gain in childhood is associated with prenatal exposure to airborne polycyclic aromatic hydrocarbons (PAH) and heavy metals (lead and mercury).The study sample comprised 379 children born to non-smoking mothers among whom a total of 2011 height measurements were carried out over the 9-year follow-up period. Prenatal airborne PAH exposure was assessed by personal air monitoring of the mother in the second trimester of pregnancy and heavy metals were measured in cord blood. At the age of 3 residential air monitoring was done to evaluate the level of airborne PAH, and at the age 5 the levels of heavy metals were measured in capillary blood.The effect estimates of prenatal PAH exposure on height growth over the follow-up were adjusted in the General Estimated Equation (GEE) models for a wide set of relevant covariates. Prenatal exposure to airborne PAH showed a significant negative association with height growth, which was significantly decreased by 1.1cm at PAH level above 34.7ng/m3 (coeff.=−1.07, p=0.040). While prenatal lead exposure was not significantly associated with height restriction, the effect of mercury was inversely related to cord blood mercury concentration above 1.2μg/L (coeff.=−1.21, p=0.020),The observed negative impact of prenatal PAH exposure on height gain in childhood was mainly mediated by shorter birth length related to maternal PAH exposure during pregnancy. The height gain deficit associated with prenatal mercury exposure was not seen at birth, but the height growth was significantly slower at later age.

Seafood consumption and umbilical cord blood mercury concentrations in a multiethnic maternal and child health cohort.

BackgroundFish consumption is common among the cultures of Hawaii, and given public health attention to mercury exposure in pregnancy, it is important to better understand patterns of fish consumption and mercury in pregnancy. This study examined the influence of maternal fish consumption during pregnancy on umbilical cord mercury (Hg) concentrations in a multiethnic cohort of women in Hawaii.MethodsThis secondary analysis of a prospective cohort pilot study examined antenatal seafood consumption and neonatal outcomes in Hawaii. The first 100 eligible women who consented were enrolled. After delivery, umbilical cord blood and a dietary survey were obtained.ResultsMost women (86%) consumed seafood during the month prior to delivery. Overall, 9% of women consumed more than the recommended limit of 12 ounces/week. Seafood consumption varied significantly by ethnicity and income, with 30% of poor women consuming more than the recommended limit. Seafood consumption did not vary by age or education.Umbilical cord blood Hg levels were 5 μg/L or more in 44% of women. Filipina were significantly less likely to have elevated Hg levels compared with non- Filipina (p < .05). Mercury levels did not vary by other demographic characteristics.Women reporting consumption exceeding 12 ounces fish per week were significantly more likely to have cord blood Hg levels of 5 μg/L or more, but mean Hg concentrations were not significantly higher (6.1 ± 3.3 v 5.0 ± 3.7). The odds ratio for elevated Hg, however, was significant among seafood-consumers compared with non-consumers (5.7; 95% confidence interval: 1.2, 27.1).ConclusionsDespite Environmental Protection Agency (EPA) guidelines, a significant portion of pregnant women consumed more than the recommended amount of seafood, which was associated with race and income. Further, almost half of study participants had cord blood Hg concentrations at or exceeding 5 μg/L.

Effect of hemoglobin adjustment on the precision of mercury concentrations in maternal and cord blood

The cord-blood mercury concentration is usually considered the best biomarker in regard to developmental methylmercury neurotoxicity. However, the mercury concentration may be affected by the binding of methylmercury to hemoglobin and perhaps also selenium. As cord-blood mercury analyses appear to be less precise than suggested by laboratory quality data, we studied the interrelationships of mercury concentrations with hemoglobin in paired maternal and cord blood samples from a Faroese birth cohort (N=514) and the Mothers and Children׳s Environmental Health study in Korea (n=797). Linear regression and structural equation model (SEM) analyses were used to ascertain interrelationships between the exposure biomarkers and the possible impact of hemoglobin as well as selenium. Both methods showed a significant dependence of the cord-blood concentration on hemoglobin, also after adjustment for other exposure biomarkers. In the SEM, the cord blood measurement was a less imprecise indicator of the latent methylmercury exposure variable than other exposure biomarkers available, and the maternal hair concentration had the largest imprecision. Adjustment of mercury concentrations both in maternal and cord blood for hemoglobin improved their precision, while no significant effect of the selenium concentration in maternal blood was found. Adjustment of blood–mercury concentrations for hemoglobin is therefore recommended.