Secondhand tobacco smoke: a source of lead exposure in US children and adolescents.

OBJECTIVES We evaluated the relationship between secondhand tobacco smoke (SHS) exposure and blood lead levels in US children and adolescents. METHODS We analyzed data from 6830 participants aged 3-19 years in the National Health and Nutrition Examination Survey (1999-2004) who were not active smokers and for whom SHS exposure information and blood lead measurements were available. RESULTS After multivariable adjustment, participants in the highest quartile of serum cotinine (≥ 0.44 μg/L) had 28% (95% confidence interval = 21%, 36%) higher blood lead levels than had those in the lowest quartile (< 0.03 μg/L). Similarly, blood lead levels were 14% and 24% higher in children who lived with 1 or with 2 or more smokers, respectively, than they were in children living with no smokers. Among participants for whom lead dust information was available, the associations between SHS and blood lead levels were similar before and after adjustment for lead dust concentrations. CONCLUSIONS SHS may contribute to increased blood lead levels in US children. Lead dust does not appear to mediate this association, suggesting inhalation as a major pathway of exposure. Eliminating SHS exposure could reduce lead exposure in children.