Fine particulate matter exposure and sperm DNA fragmentation in US men: a spatial cross-sectional study
Bibliographic record
Abstract
STUDY QUESTION: Does exposure to fine particulate matter (PM2.5) impact sperm DNA fragmentation? SUMMARY ANSWER: Higher PM2.5 exposure was associated with increased sperm DNA fragmentation, with greater effects observed in men of lower socioeconomic status (SES). WHAT IS KNOWN ALREADY: Environmental air pollutants such as PM2.5 have been linked to adverse reproductive and perinatal outcomes. However, their impact on sperm chromatin integrity remains underexplored, particularly in the context of geographic and sociodemographic modifiers. STUDY DESIGN, SIZE, DURATION: This was a cross-sectional study including 21 851 semen samples collected between 2005 and 2022 from men undergoing fertility evaluation across multiple US regions. PARTICIPANTS/MATERIALS, SETTING, METHODS: Semen samples were obtained from men older than 18 years, with testing performed in a single reference laboratory. Exposure to PM2.5 was estimated using validated satellite-derived models and aligned with the 70-80 day spermatogenic window prior to sample collection. Spatial linear mixed-effects models incorporating natural splines and geographic correlation structures were used to assess nonlinear associations between PM2.5 and sperm DNA fragmentation index (DFI), while adjusting for age, SES, population density, and racial composition. Interaction terms were used to evaluate effect modification. MAIN RESULTS AND THE ROLE OF CHANCE: Higher PM2.5 exposure was associated with increased DFI (estimate = 0.45; P = 0.0025), with a clear nonlinear dose-response pattern peaking at ∼11 µg/m³. A significant interaction was observed between PM2.5 and SES (estimate = 0.45; P = 0.0148), indicating that men from lower SES areas experienced stronger pollution-related DNA damage. Age remained a strong independent predictor: men ≥50 years showed markedly elevated DFI (estimate = 14.36; P < 0.0001). LIMITATIONS, REASONS FOR CAUTION: The sample was derived from men seeking fertility evaluation and may not represent the general population. ZIP-code level SES and exposure proxies may not reflect to the full extent an individual-level exposures, and residual confounding is possible. WIDER IMPLICATIONS OF THE FINDINGS: These results underscore the reproductive health consequences of environmental air pollution and its intersection with social inequality. PM2.5 exposure may disproportionately affect sperm chromatin quality in disadvantaged populations; this finding supports targeted environmental and reproductive health interventions. Sperm DNA fragmentation may serve as a biomarker of environmental and social stress. STUDY FUNDING/COMPETING INTEREST(S): This study was internally funded. V.X.D. and B.M. are employees of ReproSource, which provided laboratory testing, and Quest Diagnostics. No other conflicts of interest were reported. TRIAL REGISTRATION NUMBER: N/A.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.002 | 0.003 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.001 | 0.002 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".