Pagani LS, Nguyen A K D, Fitzpatrick C. (2015). Prospective associations between early long-term household secondhand smoke exposure and subsequent indicators of metabolic risk at age 10. Nicotine and Tobacco Research. 43, 584-591.
Introduction: Although there are established risks associated with gestational tobacco smoke exposure, few studies have addressed the metabolic hazards of domestic exposure in early childhood. This study prospectively examines the long-term relationship between early childhood exposure to household smoke and two adiposity-related measures at age 10. Methods: Participants from the Quebec Longitudinal Study of Child Development birth cohort were categorized into one of three groups of early childhood household exposure to tobacco smoke over four time points (from ages 1 to 7 years): never-exposed; transient exposure; and continuous exposure. Follow-up measures of body mass index and waist circumference were independently assessed at age 10. Results: Compared to being never exposed, transient and continuous household smoke exposure predicted increases of 0.93 cm (95% confidence interval [CI] between 0.05 and 1.82 cm; P = .03) and 1.56 cm (95% CI between 0.07 and 3.05 cm; P = .04) in children’s waist circumference, respectively. Children exposed to transient and continuous household smoke, compared to unexposed children, also showed 0.48 and 0.81 point increases in their body mass index, respectively, both Ps = .005. Once adjusted, for confounding variables, only transient household smoke remained associated with 43% greater odds of belonging to the overweight/obese category (95% CI between 1.12 and 1.81 cm; P < .01). Conclusions: We found significant long-term prospective associations between home-based secondhand smoke exposure and unhealthy body fat distribution. Waist circumference in youth has become an important risk factor for obesity-related diseases in adulthood. Our findings emphasize the importance public health initiatives and parental sensitization aimed at domestic exposure reductions during the critical early childhood years.