Correlation of tobacco smoke exposure to intelligence quotient in preschool children

Background Exposure to tobacco smoke at home happens in 29-69% of children globally and 43% of Indonesian children. Smoke exposure during the developmental stage may affect cognitive abilities, as measured by intelligence quotient (IQ). There have been few studies conducted on the correlation of tobacco smoke exposure to IQ. This is the first study of this type in Indonesia. Objectives To assess the correlation between tobacco smoke exposure and IQ in preschool children and to assess the correlation between serum cotinine levels and IQ in preschool children exposed to tobacco smoke. Methods A cross-sectional study was conducted in the Tuminting district, Manado in January - May 2011. Subjects were collected by random sampling of 3-5 year-old children. In our study, 35 children were deemed to have been exposed to tobacco smoke by serum cotinine >= 0.05 ng/ml and 25 children were deemed to not have been exposed to tobacco smoke (cotinine < 0.05 ng/ml). Results were analyzed by t-test and simple correlation analysis using SPSS version 17 software with a significance level of P < 0.05. Results There was a statistically significant difference in IQ between the two groups, with mean IQ of 106.54 in the group exposed to tobacco smoke and mean IQ of 109.36 in the group not exposed to tobacco smoke (P=0.01). The mean serum cotinine level in the group with tobacco smoke exposure was 1.77 ng/mL. There was no correlation between the mean level of cotinine and mean IQ in this group (r = -0.19 and P=0.14). Conclusions The mean IQ in the group with tobacco smoke exposure was lower than that of the group not exposed to tobacco smoke. There was no correlation between mean serum cotinine level and mean IQ.