Hazardous air pollutants and telomere length in the Sister Study

Abstract

Background: Telomeres are vital for genomic integrity and telomere length has been linked to many adverse health outcomes. Some hazardous air pollutants, or air toxics, increase oxidative stress and inflammation, two possible determinants of shortened telomere length. No studies have examined air toxic-telomere length associations in a non-occupational setting.

Methods: This study included 731 Sister Study participants (enrolled 2003-2007) who were randomly selected to assess telomere length in baseline blood samples. Multiplex qPCR was used to determine telomere to single copy gene (T/S) ratios. Census tract concentration estimates of 29 air toxics from the 2005 National Air Toxics Assessment were linked to baseline residential addresses. Air toxics were classified into tertile-based categories of the exposure. Multivariable linear regression was used to estimate β coefficients and 95% confidence intervals (CI) in single pollutant models. Multipollutant groups were identified with regression trees.

Results: The average T/S ratio was 1.24. Benzidine (T3vsT1 β= -0.08; 95% CI: -0.14, -0.01) and 1,4-dioxane (T3vsT1 β= -0.06; 95% CI: -0.13, 0.00) in particular, as well as carbon tetrachloride, chloroprene, ethylene dibromide, and propylene dichloride, were associated with shorter relative telomere length. Benzidine (p=0.02) and 1,4-dioxane (p=0.06) demonstrated some evidence of a monotonic trend. The regression tree identified age, BMI, physical activity, ethylene oxide, acrylonitrile, ethylidene dichloride, propylene dichloride, and styrene in multipollutant groups related to telomere length.

Conclusions: In this first study of air toxics and telomere length in a non-occupational setting, several air toxics, particularly 1,4-dioxane and benzidine, were associated with shorter relative telomere length.

Figure 1.

Regression tree for hazardous air pollutants and telomere length (TL): The Sister Study.