Second Hand Smoke Exposure in Infancy is Associated With Academic and Behavioral Outcomes in Adolescence

• In Event: 3-011 - Multi-Faceted Risk Exposure and Outcomes Through Early Adolescence: Transdisciplinary Findings from the Family Life Project

Integrative Statement

The dangers of environmental tobacco smoke have become increasingly documented as studies have demonstrated how smoke pervades the environment beyond its airborne phase and settles as an invisible residue across all surfaces in the home. This may be especially dangerous for infants, who spend significant time on the floor, and frequently explore their environment orally. Second-hand smoke exposure was examined in children from the Family Life Project, a longitudinal study consisting of 1,292 families residing in one of 6 rural counties in Pennsylvania or North Carolina, and oversampled for poverty. Cotinine, a metabolite of nicotine, was assayed from saliva when participant children were 6, 15, 24, and 48 months of age. Results indicate that this sample evidenced greater prevalence and magnitude of exposure relative to nationally representative samples. At 6 months of age, only 8.5% of the sample had no detectable exposure, whereas 12% of children had cotinine levels exceeding the threshold used to define active smoking in adults. Average exposure across the 4 assessments was negatively correlated with income-to-needs ratio, suggesting that environmental tobacco exposure may be a correlated risk of poverty.

Regression analyses were used to examine whether early cotinine exposure predicted behavioral and academic outcomes in later childhood, beyond other risks associated with poverty. Step 1 of the regression analyses included child sex and family income-to-needs ratio over the first 4 years of the child’s life. Additional covariates were taken from the assessment conducted when the child was 15 months of age and included: caregivers’ self-reported depression, as well as observer ratings of caregiver affection, caregiver hostility, caregiver’s verbal engagement, and environmental enrichment, using the HOME inventory. Cotinine was entered in Step 2 to determine whether it had a predictive association with behavioral outcomes beyond the variance accounted for by the variables in step 1. Behavioral outcomes were measured by teacher report using the Strengths and Difficulties Questionnaire, averaged across all available reports from preschool to 5th grade. Academic outcomes were assessed with the Woodcock Johnson administered when children were in the 5th grade.

For all behavioral subscales; conduct problems, emotional symptoms, peer problems, and hyperactivity, higher cotinine levels significantly predicted more behavioral problems beyond the variance accounted for in Step 1. For all subscales of the Woodcock Johnson; letter word identification, passage comprehension, applied problems, picture vocabulary, and brief reading score, Step 1 was a significant predictor with lower income-to-needs ratios predicting worse academic achievement. The significance of additional covariates included in Step 1 varied slightly by subscale. Step 2 emerged as significant for the passage comprehension and brief reading subscales only. Greater exposure to second-hand smoke in infancy was associated with worse reading performance in 5th grade, even after controlling for children’s exposure to verbal input from the caregiver and presence of educationally enriching toys during toddlerhood, factors shown to mediate the effects of poverty on academic readiness. These results suggest that environmental exposure to neurotoxins may represent an additional mechanism by which cognitive and behavioral development is impeded among children living in poverty.

Authors

• Lisa Gatzke-kopp, Penn State University
  Presenting Author

• Michael T Willoughby, RTI International
  Non-Presenting Author

• Siri Warkentien, RTI International
  Non-Presenting Author