[Show abstract][Hide abstract] ABSTRACT: Background and Aims: The controversial topic of the early human exposure to mercury is ethylmercury, which is present in the thimerosal-containing vaccines (TCV). The objective of this analysis was to determine the relationship between the neonatal exposure to TCV and cognitive and psychomotor development of children during the first 2 years of life.
[Show abstract][Hide abstract] ABSTRACT: In the last decade, the neurologic effects of various air pollutants have been the focus of increasing attention. The main purpose of this study was to assess the potential impact of early childhood exposure to indoor molds on the subsequent cognitive function of 6-year old children. The results of this study are based on the six-year follow-up of 277 babies born at term to mothers participating in a prospective cohort study in Krakow, Poland. The study participants are all non-smoking pregnant women who were free of chronic diseases such as diabetes and hypertension. The presence of visible mold patches on indoor walls was monitored at regular time intervals over gestation and after birth up to the age of five. The Wechsler Intelligence Scale for Children (WISC-R) was administered to children at age 6. The exposure effect of living in mold-contaminated homes on the IQ scores of children was adjusted for major confounders, known to be important for the cognitive development of children such as maternal education, the child's gender, breastfeeding practices in infancy, the presence of older siblings and the prenatal exposure to lead and environmental tobacco smoke (ETS). The adjusted IQ deficit attributed to longer exposures to indoor molds (>2 years) was significantly lower on the IQ scale (beta coeff.=-9.16, 95%CI: -15.21, -3.10) and tripled the risk of low IQ scoring (OR=3.53; 95%CI: 1.11-11.27) compared with references. While maternal education (beta coeff.=0.61, 95%CI: 0.05, 1.17) and breastfeeding (beta coeff.=4.0; 95%CI: 0.84, 7.17) showed a significant positive impact on cognitive function, prenatal ETS exposure (beta coeff.=-0.41; 95%CI: -0.79, -0.03) and the presence of older siblings (beta coefficient=-3.43; 95%CI: -5.67, -1.20) were associated with poorer cognitive function in children. In conclusion, the results of this study draw attention to the harmful effect of early postnatal exposure to indoor molds on children's cognitive development and provide additional evidence on the role of environmental determinants in human cognitive development.
[Show abstract][Hide abstract] ABSTRACT: The main goal of the study was to assess the effect of exclusive breastfeeding on the neurodevelopment of children over a 7-year follow-up period and to test the hypothesis that the observed cognitive gain in breastfed children in the first years of life is a strong predictor of their cognitive development trajectory, which may be continued in later life. The analysis is based on data from the 7-year follow-up of 468 term babies (>36 weeks of gestation) born to non-smoking mothers participating in an ongoing prospective cohort study. The cognitive function of children was assessed by psychometric tests performed five times at regular intervals from infancy through the preschool age. The study included valid neurodevelopmental assessment of the children-443 participants were evaluated least twice; 425, three times; and 307, five times in the follow-up period. The association between the cognitive achievements of preschool age children and exclusive breastfeeding of various durations was performed using the generalized estimating equation longitudinal model, adjusted for major confounders such as maternal education, gender, parity, and weight gain in pregnancy. Children breastfed exclusively for up to 3 months had intelligence quotients (IQs) that were on average 2.1 points higher compared to the others (95% confidence interval (CI), 0.24-3.9); children breastfed for 4-6 months scored higher by 2.6 points (95% CI, 0.87-4.27); and the benefit for children breastfed even longer (>6 months) increased by 3.8 points (95% CI, 2.11-5.45). Other predictors were maternal education, gender of the child, having an older sibling, and weight gain during pregnancy. The results of the study support the WHO expert recommendations on exclusive breastfeeding for 6 months; moreover, they provide evidence that even a shorter duration of exclusive breastfeeding in early infancy produces beneficial effects on the cognitive development of children. The breastfeeding-related IQ gain observed already at the age of 1 was sustained through preschool age, and the difference in terms of IQ score between breastfed children and the reference group (mixed breastfeeding) held constant over the whole preschool period.
European Journal of Pediatrics 06/2011; 171(1):151-8. · 1.98 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The main purpose of the study was to answer the question whether young children without clinical diagnosis of asthma but experiencing early wheezing disorders and therefore being at high risk of developing asthma may have cognitive deficits. In the ongoing birth cohort study wheezing symptoms were recorded postpartum over two first years of age and subsequently cognitive status of children at the age of 3 yr was assessed with the Bayley Mental Development Index (MDI). In the statistical analysis a wide range of modifying and confounding factors (maternal education, gender of children, prenatal exposure to lead and environmental tobacco smoke (ETS) were considered to assess the independent effect of early wheezing phenotypes on cognitive development of children. The MDI score correlated inversely with the number of wheezing days recorded over 24 months (r = -0.13, p = 0.007), lead cord blood concentration (r = -0.12, p = -0.02), number of siblings (r = -0.17, p = 0.0006) and the number of cigarettes smoked daily by other household members at home over the pregnancy period (r = -0.18, p = 0.0002). While the children who experienced wheezing over the first year of age showed deficit of 2 MDI scores (beta coeff. = -2.31, 95%CI: -4.63 to 0.02), those with persistent wheezing had the score deficit of 4 points (beta coeff. = -4.41, 95%CI: -8.27 to -0.55). To our knowledge, it is the first report in the iterature showing that early wheezing is associated the cognitive deficit in a community-recruited very young children. Observed cognitive deficit in early wheezers may be caused by RSV infections or can be related to lower lung function attributed to persistent wheezing, which reducing oxygen supply would affect rapidly developing brain.
Pediatric Allergy and Immunology 07/2009; 21(3):550-6. · 3.38 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The primary purpose of this study was to assess the relationship between very low-level of prenatal lead exposure measured in the cord blood (<5 microg/dL) and possible gender-specific cognitive deficits in the course of the first three years of life. The accumulated lead dose in infants over the pregnancy period was measured by the cord blood lead level (BLL) and cognitive deficits were assessed by the Bayley Mental Development Index (MDI). The study sample consisted of 457 children born to non-smoking women living in the inner city and the outlying residential areas of Krakow. The relationship between prenatal lead exposure and MDI scores measured at 12, 24 and 36 months of age and adjusted to a set of important covariates (gender of child, maternal education, parity, breastfeeding, prenatal and postnatal environmental tobacco smoke) was evaluated with linear multivariate regression, and the Generalized Estimating Equations (GEE) longitudinal panel model. The median of lead level in cord blood was 1.21 microg/dL with the range of values from 0.44 to 4.60 microg/dL. Neither prenatal BLL (dichotomized by median) nor other covariates affected MDI score at 12 months of age. Subsequent testing of children at 24 months of age showed a borderline significant inverse association of lead exposure and mental function (beta coefficient=-2.42, 95%CI: -4.90 to 0.03), but the interaction term (BLL x male gender) was not significant. At 36 months, prenatal lead exposure was inversely and significantly associated with cognitive function in boys (Spearman correlation coefficient=-0.239, p=0.0007) but not girls (r=-0.058, p=0.432) and the interaction between BLL and male gender was significant (beta coefficient=-4.46; 95%CI: -8.28 to -0.63). Adjusted estimates of MDI deficit in boys at 36 months confirmed very strong negative impact of prenatal lead exposure (BLL>1.67 microg/dL) compared with the lowest quartile of exposure (beta coefficient=-6.2, p=0.002), but the effect in girls was insignificant (beta coefficient=-0.74, p=0.720). The average deficit of cognitive function in the total sample over the first three years of life (GEE model) associated with higher prenatal lead exposure was also significant (beta coefficient=-3.00; 95%CI: -5.22 to -0.70). Beside prenatal lead exposure, presence of older siblings at home and prenatal environmental tobacco smoke had a negative impact on MDI score. Better maternal education showed a strong beneficial effect on the cognitive development of children. Conclusion: the study suggests that there might be no threshold for lead toxicity in children and provides evidence that 3-year old boys are more susceptible than girls to prenatal very low lead exposure. The results of the study should persuade policy makers to consider gender-related susceptibility to lead and possibly to other toxic hazards in setting environmental protection guidelines. To determine whether the cognitive deficit documented in this study persists to older ages, the follow-up of the children over the next several years is to be carried out.
Early human development 06/2009; 85(8):503-10. · 2.12 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The primary purpose of the study was to establish a possible association between very low levels of prenatal exposure to lead and mental development of children at 12, 24 and 36 months of age.
The study sample consisted of 444 children born to mothers who attended ambulatory prenatal clinics in Krakow inner city in the first and second trimesters of pregnancy. We assessed exposure to lead by the cord blood lead measurements, and mental development in infancy and early childhood using the Bayley Mental Development Index (MDI). The relationship between prenatal lead exposure and MDI scores at each follow-up period was evaluated with linear multivariate regression. To test the overall effect of maternal exposure to lead during pregnancy on the Bayley test scores at 12, 24 and 36 months of age, we used the generalized estimating equations (GEE) longitudinal panel model as well.
The median lead level in cord blood was 1.23 microg/dl, in the range of 0.44-6.90 microg/dl. An adverse effect of prenatal lead exposure (log-transformed lead concentrations) on MDI scores at 12 months of age was of border significance (beta = -5.42, 95% CI: -11.19 to 0.35). Subsequent testing of children at 24 months of age showed a significant inverse association of mental function and lead exposure (beta = -7.65, 95% CI: -14.68 to -0.62). A significant deficit in cognitive function due to prenatal lead exposure was also confirmed at 36 months of age (beta = -6.72, 95% CI: -12.5 to -0.89). The GEE panel model showed that the average deficit in the cognitive development attributable to lead exposure over 3 years was also significant (beta = -6.62, 95% CI: -1.52 to -1.72). Mental function scores of girls were better than boys, and the effect of maternal education remained strongly significant in relation to mental function of 3-year-olds.
The results of the study demonstrate that the neurotoxic impact of very low levels of prenatal lead exposure (below 5 microg/dl) may occur in infants and very young children, and suggest a revision of established health guidelines for prenatal lead exposure criteria.
[Show abstract][Hide abstract] ABSTRACT: The aim of the study is to assess the cognitive and psychomotor status of 1-year-old infants whose mothers were exposed to low, but varying, amounts of mercury during pregnancy.
Mercury levels in cord and maternal blood at delivery were used to assess prenatal environmental exposure to mercury. Bayley Scales of Infant Development were used to assess neurobehavioral health outcomes. The cohort consisted of 233 infants who were born at 33 to 42 weeks of gestation between January 2001 and March 2003 to mothers attending ambulatory prenatal clinics in the first and second trimesters of pregnancy. Enrollment included only nonsmoking women with singleton pregnancies between the ages of 18 and 35 years who were free from chronic diseases.
The geometric mean (GM) for maternal blood mercury level for the group of infants with normal neurocognitive performance was lower (GM = 0.52 mug/L; 95% confidence interval [CI], 0.46-0.58) than that observed in the group with delayed performance (GM = 0.75 mug/L; 95% CI, 0.59-0.94), and this difference was significant (p = 0.010). The GM of cord blood mercury level in the normal group also was lower (GM = 0.85 mug/L; 95% CI, 0.78-0.93) than that observed in the group with delayed performance (GM = 1.05 mug/L; 95% CI, 0.87-1.27), and this difference was of borderline significance (p = 0.070). The relative risk (RR) for delayed performance increased more than threefold (RR = 3.58; 95% CI, 1.40-9.14) if cord blood mercury level was greater than 0.80 mug/L. Risk for delayed performance in the group of infants with greater maternal mercury levels (>0.50 mug/L) also was significantly greater (RR = 2.82; 95% CI, 1.17-6.79) compared with children whose mothers had mercury levels less than 0.50 mug/L.
The results may be of public health importance because delayed psychomotor or mental performance in infants is assumed to be an indicator of later neurocognitive development in children, which may persist into adult life.
Annals of Epidemiology 06/2006; 16(6):439-47. · 2.15 Impact Factor