Exposure to polycyclic aromatic hydrocarbons, vitamin D, and lung function in children with asthma

BackgroundIt is unclear whether exposure to polycyclic aromatic hydrocarbons (PAH) affects lung function in children with asthma. Whether vitamin D insufficiency enhances any detrimental effects of PAH on lung function in asthmatic children is also unknown. MethodsCross-sectional study of 1,821 children (6-17 years) who participated in the 2007-2012 National Health and Nutrition Examination Survey. Multivariable linear regression was used to analyze the relation between molar mass of urinary PAH metabolites (sum of all PAH (sigma molPAH), sum of PAH with 2 benzene rings (sigma mol2-PAH), or sum of PAH with 3 or 4 benzene rings (sigma mol3,4-PAH)) and lung function or exhaled fraction of nitric oxide (FeNO) in children with and without asthma. In this multivariable analysis, we tested whether vitamin D insufficiency (a serum 25(OH)D level <30ng/mL) interacts with PAH exposure on lung function in children with asthma. ResultsChildren in the highest quartiles of urinary sigma mol3,4-PAH had 2.3 times increased odds of asthma than those in the lowest quartile of sigma mol3,4-PAH. Urinary PAH were not associated with lung function in children with or without asthma. Given a significant interaction between vitamin D insufficiency and PAH metabolites on lung function in asthmatic children, we stratified the analysis by vitamin D status. In this analysis, urinary PAH metabolites were significantly associated with 2.7-3.9% reduced %predicted FEV1 and %predicted FEV1/FVC in children with asthma and vitamin D insufficiency, but not in those with asthma and vitamin D sufficiency. ConclusionsVitamin D insufficiency and PAH exposure may have synergistic detrimental effects on lung function in asthmatic children.