Ambient Air Pollution, Asthma Drug Response and Telomere Length in African American Youth

Abstract Background Telomere length can serve as a potential biomarker for conditions associated with chronic oxidative stress and inflammation such as asthma. Air pollution can induce oxidative stress. Understanding the relationship between telomere length, asthma, and air pollution is important for identifying risk factors contributing to unhealthy aging in children. Objectives To investigate the associations between exposures to ambient air pollutants and telomere length (TL) in African American children and adolescents, and to examine whether African ancestry, asthma status and steroid medication use alter the association. Methods Linear regression was used to examine associations between absolute TL and the estimated annual average residential ozone (O 3 ) and fine particulate matter (PM 2.5 ) exposures in a cross-sectional analysis of 1,072 children in an existing asthma case-control study. African ancestry, asthma status and the use of steroid medications were examined as effect modifiers. Results Participants’ absolute TL was measured by quantitative polymerase chain reaction. A 1-ppb and a 1-μg/m 3 increase in annual average exposure to O 3 and PM 2.5 were associated with a decrease in absolute TL of 37.1 kb (95% CI: -66.7 kb to -7.4 kb) and 57.1 kb (95% CI: -118.1 kb to 3.9 kb), respectively. African ancestry and asthma were not effect modifiers; however, exposure to steroid medications modified the relationships between TL and the pollutants. Past year exposure to O 3 and PM 2.5 were associated with shorter TL in patients without steroid use. Conclusion Exposure to air pollution was associated with shorter telomere length in non-asthmatic children and adolescents. This was not the case for asthmatic children as a group, but those on steroid medication had less shortening than those not using steroids. Reduced exposure to air pollution in childhood may help to preserve telomere length.