Fine particulate matter exposure and sperm DNA fragmentation in US men: a spatial cross-sectional study

Area of Science:

• Environmental Health
• Reproductive Toxicology
• Sperm Biology

Background:

• Environmental air pollutants, including fine particulate matter (PM2.5), are linked to adverse reproductive outcomes.
• The impact of PM2.5 on sperm chromatin integrity is not well understood, especially considering sociodemographic factors.

Purpose of the Study:

• To investigate the association between exposure to fine particulate matter (PM2.5) and sperm DNA fragmentation.
• To explore potential effect modification by socioeconomic status (SES) and age.

Main Methods:

• Cross-sectional study of 21,851 semen samples from men undergoing fertility evaluation (2005-2022).
• PM2.5 exposure estimated using satellite-derived models for the spermatogenic window.
• Spatial linear mixed-effects models used to assess associations between PM2.5 and sperm DNA fragmentation index (DFI), adjusting for covariates and testing for interactions.

Main Results:

• Higher PM2.5 exposure was significantly associated with increased sperm DNA fragmentation (DFI).
• A nonlinear dose-response pattern was observed, with effects peaking around 11 µg/m³.
• Men of lower SES experienced greater PM2.5-related DFI increases, and age (≥50 years) was also a strong predictor of elevated DFI.

Conclusions:

• PM2.5 exposure negatively impacts sperm chromatin quality, with a disproportionate effect on men from lower SES backgrounds.
• Findings suggest sperm DNA fragmentation can serve as a biomarker for environmental and social stress.
• Results support targeted interventions addressing air pollution and social inequalities in reproductive health.