Obesogenic Effects of Exposure to Tobacco Smoke and Air Pollution in Children

摘要

Background:lncreased childhood body mass index (BMI) and obesity prevalence have been associated with exposure to tobacco smoke (secondhand smoke (SHS) and maternal smoking during pregnancy) and to vehicular air pollution. Aims: We examined the joint effects on BMI and obesity of air pollution and tobacco smoke, which could have potentially large public health impact because both are common exposures. Methods:lnformation on exposure to SHS and maternal smoking during pregnancy were collected from parents at the time of enrollment in 1993 and 1996 of a cohort of 3318 participants (mean age 10.1) into the Southern California Children's Health Study. Near-roadway pollution exposure (NRP) at each child's residence at study entry was modeled from a line source air dispersion model. The associations of exposure to tobacco smoke and NRP with BMI growth trajectory based on annual measurements and attained BMI at age 18 were assessed using a hierarchal statistical modeling framework. Results: SHS exposure was positively associated with the 8-year BMI growth (0.81 units; 95% confidence interval 0.35,1.26) and with attained BMI at age 18 (1.23 units; 0.85,1.60) compared with children without SHS exposure. Both BMI growth and attained level increased with more smokers in the home. Compared with children in homes with NRP below the median and no SHS exposure, attained BMI was greater among children in homes with high NRP and no SHS (0.65 units;0.17,1.13), with SHS and low NRP (0.84;0.40,1.28) and showed synergistic effects with both exposures (2.03;1.41,2.63), interaction P-value 0.002. A similar pattern of associations of BMI was observed with maternal smoking during pregnancy. Interpretation.The strong, synergistic associations of two combustion sources with BMI, and the unambiguous temporal relationship, strengthen emerging evidence that exposure to tobacco smoke and NRP both contribute to the development of childhood obesity.