Early life exposure to air pollution has been linked with cognitive impairment in children, but the results have not been conclusive. We analyzed the association between traffic-related air pollution and cognitive function in a prospective birth cohort in Rome.
A cohort of 719 newborns was enrolled in 2003–2004 as part of the GASPII project. At age 7 years, 474 children took the Wechsler Intelligence Scale for Children-III to assess their cognitive development in terms of IQ composite scores. Exposure to air pollutants (NO2, PMcoarse, PM2.5, PM2.5 absorbance) at birth was assessed using land use regression models. We also considered variables indicating traffic intensity. The effect of environmental pollution on IQ was evaluated performing a linear regression model for each outcome, adjusting for gender, child age at cognitive test, maternal age at delivery, parental educational level, siblings, socio-economic status, maternal smoking during pregnancy, and tester. To account for selection bias at enrollment and during follow-up, the regression models were weighted for the inverse probabilities of participation and follow-up.
A 10 μg/m3 higher NO2 exposure during pregnancy was associated with 1.4 fewer points (95% confidence interval = −2.6, −0.20) of verbal IQ, and 1.4 fewer points (95% confidence interval = −2.7, −0.20) of verbal comprehension IQ. Similar associations were found for traffic intensity in a 100 m buffer around home. Other pollutants showed negative associations with larger confidence intervals.
Consistent with previous evidence, this study suggests an association of exposure to NO2 and traffic intensity with the verbal area of cognitive development.
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From the aDepartment of Epidemiology of the Lazio Regional Health Service, Rome, Italy; bCentre for Research in Environmental Epidemiology (CREAL), Barcelona, Spain; and cDepartment of Environmental Health, Harvard School of Public Health, Boston, MA.
Submitted 3 December 2014; accepted 27 September 2015.
The research leading to these results has received funding from the European Community’s Seventh Framework Program (FP7/2007–2011) under grant agreement number 211250. The cohort study was initially funded by a grant from the Italian Ministry of Health (ex art.12, 2001).
The authors report no conflicts of interest.
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Correspondence: Daniela Porta, Department of Epidemiology of the Lazio Regional Health Service, Via Cristoforo Colombo, 112, 00137 Rome, Italy. E-mail: firstname.lastname@example.org.