Pollutants and sperm quality: a systematic review and meta-analysis.

Male fertility and semen quality have declined over recent decades. Among other causes, exposure to environmental and occupational pollution has been linked to adverse reproductive outcomes, but effects on male semen quality are still uncertain. Therefore, the aim of the present study was to conduct a systematic review and meta-analysis to assess current evidence regarding the impact of exposure to tobacco smoke and environmental and occupational pollution on sperm quality in humans. In the meta-analysis, 22 studies are included showing that environmental and occupational pollutants may affect sperm count, volume, concentration, motility, vitality and sperm DNA, and chromatin integrity. All included articles reported significant alterations in at least one of the outcomes studied in association with at least one of the pollutants studied. Considering that sperm quality can be considered a proxy for general health and that pollutants have a dramatic impact on climate change, it would be strongly recommended to better understand the role of pollutants on human, animal, and planetary health.