Particulate Pollution and Male Reproductive Health: Differential Impacts in Early and Late Spermatogenesis

Abstract

Particulate Pollution and Male Reproductive Health: Differential Impacts in Early and Late SpermatogenesisBackground/Aim: Despite increasing evidence that particulate air pollution has adverse effects on human semen quality, few studies examine clinically relevant thresholds typically employed by clinicians to diagnose male fertility problems. Furthermore, exposure is often assessed using average air pollution levels in a geographic area rather than individualized measures. Finally, physiology-driven selection exposure windows are inconsistent.Methods: We examined a previous cohort of 132 healthy males seeking to become parents, using spermatogenesis-relevant exposure windows of 77-34 days and 37-0 days prior to semen collection. Exposure to PM2.5 and PM10 was individualized by selecting multiple air pollution sensors within participants’ geographic air basins and employing inverse distance weighting to calculate mean daily exposure levels. We used multiple logistic regression to assess the association between pollution, temperature, and dichotomized World Health Organization semen parameters.Results: During the early phase of spermatogenesis, air pollution exposure is associated with 1.563 (95% CI, 1.049 to 2.452) times greater odds of <30% normal heads per 1-unit increase in IQR for PM2.5. In the late phase of spermatogenesis, air pollution exposure is associated with 0.368 (95% CI, 0.114 to 0.767) times greater odds of semen concentration <15 million/mL per 1-unit increase in IQR for PM2.5, and 0.208 (95% CI, 0.042 to 0.653) for PM10.Conclusions: Particulate exposure has a differential and more deleterious impact on early-phase spermatogenesis than late-phase, especially for PM2.5.This suggests that smaller particles breathed earlier in the spermatogenic cycle are likelier to affect sperm head formation.