The key facts

  • Men with higher concentrations of polystyrene, PVB, and PET had lower sperm motility
  • Participants also showed changes in gut microbiota, providing grounds for a hypothesis about the role of gut bacteria
  • The authors acknowledge that only a statistical association, not causation, has been established

What the researchers found

Exposure to microplastics may be linked to reduced sperm motility — this is the conclusion reached by Chinese scientists whose study was published in the journal Frontiers in Public Health. The study involved men who visited a reproductive medicine clinic in the city of Jinan in Shandong province from April to July 2023: their sperm quality was assessed, microplastic content in stool samples was measured, and the composition of their gut microbiota was analyzed.

Which types of plastic turned out to be significant

The analysis showed that higher concentrations of certain types of plastic particles correlated with lower overall sperm motility. The association was found for polystyrene (PS), polyvinyl butyral (PVB), and polyethylene terephthalate (PET) — the latter is widely used in the production of plastic packaging. Motility matters because male reproductive cells must travel through the vagina, cervix, and uterine cavity to reach the fallopian tubes, where they meet the egg; cells with poor motility cannot cover this distance.

The role of microbiota and limitations of the study

An additional finding: men with impaired sperm motility showed changes in the composition of their gut microbiota. This led the authors to suggest that gut bacteria may be involved in the mechanism linking microplastics to reproductive indicators. However, the researchers explicitly note that the study does not prove that microplastics directly impair sperm quality — only a statistical association was established, and further research is needed to confirm a cause-and-effect mechanism. Separately, Gazeta.Ru notes an earlier report by scientists that nuts may improve sperm quality.