Hansen, C; Luben, TJ; Sacks, JD; Olshan, A; Jeffay, S; Strader, L; Perreault, SD
Background: Research has suggested an association with ambient air pollution and sperm quality.Objectives: We investigated the effect of exposure to ozone (O3) and particulate matter < 2.5 microm in aerodynamic diameter (PM2.5) on sperm quality.Methods: We reexamined a previous cohort study of water disinfection by-products to evaluate sperm quality in 228 presumed fertile men with different air pollution profiles. Outcomes included sperm concentration, total sperm per ejaculate (count), and morphology, as well as DNA integrity and chromatin maturity. Exposures to O3 and PM2.5 were evaluated for the 90-day period before sampling. We used multivariable linear regression, which included different levels of adjustment (i.e., without and with season and temperature) to assess the relationship between exposure to air pollutants during key periods of sperm development and adverse sperm outcomes.Results: Sperm concentration and count were not associated with exposure to PM2.5, but there was evidence of an association (but not statistically significant) with O3 concentration and decreased sperm concentration and count. Additionally, a significant increase in the percentage of sperm cells with cytoplasmic drop [beta = 2.64; 95% confidence interval (CI), 0.215.06] and abnormal head (beta = 0.47; 95% CI, 0.030.92) was associated with PM2.5 concentration in the base model. However, these associations, along with all other sperm outcomes, were not significantly associated with either pollutant after controlling for season and temperature. Overall, although we found both protective and adverse effects, there was generally no consistent pattern of increased abnormal sperm quality with elevated exposure to O3 or PM2.5.Conclusions: Exposures to O3 or PM2.5 at levels below the current National Ambient Air Quality Standards were not associated with statistically significant decrements in sperm outcomes in this cohort of fertile men. However, some results suggested effects on sperm concentration, count, and morphology. Editor's SummaryAdverse effects of air pollution on sperm quality have been reported, but few studies have evaluated ambient exposures consistent with U.S. regulatory guidelines. Hansen et al. (p. 203) studied levels of ozone (O3) and PM2.5 (particulate matter < 2.5 microm in aerodynamic diameter) in association with semen outcomes among 228 presumed-fertile men residing in three southeastern U.S. counties. Exposures were classified based on measurements averaged across fixed monitoring stations in each county during the 90 days before sample collection. Outcomes included sperm concentration, count (per ejaculate) and morphology, and proxy measures of DNA integrity (sperm chromatin structure assay) and chromatin maturity (CMA assay). Associations with exposures during key time windows of sperm development were estimated using multivariable linear regression. The authors report crude inverse associations for O3 and sperm concentration and count, and positive associations for PM2.5 and the proportion of sperm cells with cytoplasmic drop and abnormal heads; however, associations did not persist after adjustment for season and temperature. Overall, O3 and PM2.5 exposures in the study population were not clearly associated with adverse outcomes, but the authors conclude that better characterized exposure estimates are needed to clarify relations between air pollutants and sperm quality.