The effect of ambient air pollution on sperm quality

Abstract

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.

Figure 1

Results of multivariable linear regression by sperm quality parameter for the four exposure windows for PM_2.5 (model 3). Abbreviations: Abn, abnormal; Conc., concentration; cyt, cytology; mid, midsection.

Figure 2

Results of multivariable linear regression by sperm quality parameter for the four exposure windows for O₃ (model 3). Abbreviations: Abn, abnormal; Conc., concentration; cyt, cytology; mid, midsection.