Environment/Climate Change
Impact of exposure to air pollution mixtures on sperm epigenetic age Carrie Nobles* Carrie Nobles Timothy Canty Pauline Mendola Lindsey M Russo Kaniz Rabeya Karen C Schliep Akanksha Singh Allison M Ring Rachael Hemmert Neil J Perkins C Matthew Peterson Erica B Johnstone J Richard Pilsner
Introduction: While air pollution is associated with decrements in semen quality, underlying mechanisms and impacts on fertility remain less understood. Air pollution-induced redox stress may disrupt the blood-testes barrier similar to aging, leading to changes in sperm DNA methylation associated with poorer semen quality and longer time to pregnancy.
Methods: We evaluated air pollution and sperm epigenetic age (SEA), the acceleration or deceleration of age-related changes in sperm DNA methylation, among 1220 men in the FAZST Trial (2013-2018) from Utah, residing predominately along the Wasatch Front. Residential exposure to nitrogen dioxide (NO2), ozone (O3), sulfur dioxide (SO2), and fine particulate matter (PM2.5) and its constituents was estimated by the Community Multiscale Air Quality Model fused with monitor data and averaged across susceptible windows of spermatogenesis. Single- and multipollutant models and mixture models (quantile-based g-computation) adjusted for participant characteristics. Secondary analyses adjusted for season and temperature.
Results: We observed accelerated SEA with higher O3, higher NO2, and lower SO2 (e.g. MD 0.292 [95% CI 0.030, 0.553], MD 0.192 [95% CI -0.049, 0.434], and MD -0.052 [95% CI -0.118, 0.015] years per IQR in multipollutant models during mitosis, respectively), with no clear associations for total PM2.5. In mixture models breaking down PM2.5 constituents, the air pollution mixture was associated with accelerated SEA (e.g. MD 0.211 [95% CI 0.003, 0.420] years per quantile increase during meiosis), with O3, NO2, sulfates, and nitrates contributing most strongly to positive weights (e.g. 32.8%, 30.8%, 19.6%, and 15.2%, respectively, during meiosis). Findings were similar adjusting for season and temperature.
Discussion: Exposure to air pollution during cell division stages of spermatogenesis along the Wasatch Front was associated with accelerated SEA, with NO2 and its secondary pollutants the strongest contributors.