Prenatal exposure to polycyclic aromatic hydrocarbons and cognitive dysfunction in children

Abstract

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.

Impact of prenatal polycyclic aromatic hydrocarbon exposure on behavior, cortical gene expression, and DNA methylation of the Bdnf gene

“…In humans, elevated in utero PAH exposure has been linked to reductions in verbal IQ [35] and decreased processing speed during cognitive testing [7]. Our analyses indicated a reduced preference for the novel object in PAH-exposed males, attributed to the greater preference for the familiar vs. the novel object (see Figure 4B).…”

Association between prenatal exposure to ambient diesel particulate matter and perchloroethylene with children's 3rd grade standardized test scores

“…For example, higher levels of black carbon and polycyclic aromatic hydrocarbons, two other common measures of TRAP, have been associated with lower cognitive function in children. (Jedrychowski et al, 2015; Suglia et al, 2008) Additionally, noise exposure co-varies with air pollutant levels in New York City (Kheirbek et al, 2014), and animal research suggests that maternal exposure to noise stress during pregnancy can disturb cognition in offspring. (Barzegar et al, 2015) It is possible that unaccounted for pollutants could lead to our results, which would suggest that diesel PM and perchloroethylene are just proxies for these other pollutants.…”

“…Analysis of other birth cohorts has produced similar results when examining air pollutants and children's neurodevelopment. (Chiu et al, 2013; Freire et al, 2010; Guxens et al, 2012; Harris et al., 2015; Jedrychowski et al, 2015; Kim et al, 2014)…”

Environmental PAH exposure and male idiopathic infertility: a review on early life exposures and adult diagnosis

“…However, the cellular junctions in the fetal BBB are known to be leaky toward lipophilic compounds, relative to those of mature adults, and PAHs have been found to cross the BBB in adults [7, 33, 34]. There is growing evidence that PAH exposure in utero and in early childhood results in a number of cognitive and intellectual disadvantages [7, 35–37]. Androgen and estrogen receptors are present in the brain and brain development is affected by levels of sex steroids present in the fetal environment [38].…”