Prenatal exposure to polycyclic aromatic hydrocarbons and cognitive dysfunction in children.

Polycyclic aromatic hydrocarbons (PAHs) are widespread environmental pollutants produced by combustion of fossil fuel and other organic materials. Both experimental animal and human studies have reported the harmful impacts of PAH compounds on fetal growth and neurodevelopment, including verbal IQ of children. Here, we have assessed the association between cognitive function of children and prenatal PAH exposures. The study is part of an ongoing, longitudinal investigation of the health effects of prenatal exposure to air pollution on infants and children in Krakow, Poland. The subjects in this report included 170 children whose mothers were enrolled to the study in the first or second trimester of pregnancy whose cord blood were tested for PAH-DNA adducts and who were assessed at age 7 using the Wechsler Intelligence Scale for Children-Revised (WISC-R). The outcome of a priori interest was depressed verbal IQ index (DepVIQ), which is the difference between WISC-R performance and verbal IQ scores. Prenatal PAH exposure was measured by cord blood PAH-DNA adducts, an individual dosimeter, integrating exposure from various sources of exposure over the gestational period. The estimated effect of prenatal PAH exposure on cognitive function was adjusted in multivariable regression for a set of potential confounders (child's gender, parity, maternal education, breastfeeding practice, environmental tobacco smoke (ETS), and postnatal PAH exposure). The prevalence of DepVIQ was significantly higher in children with detectable PAH-DNA adducts compared to those with undetectable adducts (13.7 vs. 4.4 %,). Binary multivariable regression documented that the relative risk of DepVIQ increased threefold with a ln-unit increase in cord blood adducts (relative risk (RR) = 3.0, 95 % confidence interval (CI) 1.3-6.8). Postnatal PAH exposure also increased the risk of DepVIQ (RR = 1.6, 95 % CI 1.1-2.5). Long-term exclusive breastfeeding (at least 6 months) showed a protective effect (RR = 0.3, 95 % CI 0.1-0.9). In conclusion, these results provide further evidence that PAHs are harmful to the developing fetal brain with effects extending through childhood, with implications for the academic success of the children.

Effect of exclusive breastfeeding on the development of children's cognitive function in the Krakow prospective birth cohort study.

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.

Cognitive function of 6-year old children exposed to mold-contaminated homes in early postnatal period. Prospective birth cohort study in Poland.

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.

Prenatal exposure to airborne polycyclic aromatic hydrocarbons and children's intelligence at 5 years of age in a prospective cohort study in Poland.

BACKGROUND: In this prospective cohort study of Caucasian mothers and children in Krakow, Poland, we evaluated the role of prenatal exposure to urban air pollutants in the pathogenesis of neurobehavioral disorders. OBJECTIVES: The objective of this study was to investigate the relationship between prenatal polycyclic aromatic hydrocarbon (PAH) exposure and child intelligence at 5 years of age, controlling for potential confounders suspected to play a role in neurodevelopment. METHODS: A cohort of pregnant, healthy, nonsmoking women was enrolled in Krakow, Poland, between 2001 and 2006. During pregnancy, participants were invited to complete a questionnaire and undergo 48-hr personal air monitoring to estimate their babies' exposure, and to provide a blood sample and/or a cord blood sample at the time of delivery. Two hundred fourteen children were followed through 5 years of age, when their nonverbal reasoning ability was assessed using the Raven Coloured Progressive Matrices (RCPM). RESULTS: We found that higher (above the median of 17.96 ng/m3) prenatal exposure to airborne PAHs (range, 1.8-272.2 ng/m3) was associated with decreased RCPM scores at 5 years of age, after adjusting for potential confounding variables (n = 214). Further adjusting for maternal intelligence, lead, or dietary PAHs did not alter this association. The reduction in RCPM score associated with high airborne PAH exposure corresponded to an estimated average decrease of 3.8 IQ points. CONCLUSIONS: These results suggest that prenatal exposure to airborne PAHs adversely affects children's cognitive development by 5 years of age, with potential implications for school performance. They are consistent with a recent finding in a parallel cohort in New York City.