Microplastics and male reproductive toxicity: Research progress on injury pathways and regulatory mechanisms.

Microplastics and nanoplastics are ubiquitous across global environments and can bioaccumulate through food chains, arousing concerns over their links to rising rates of male infertility. Relevant literature was retrieved from PubMed, Web of Science Core Collection and Scopus, and eligible original human, animal and cell studies were screened and analyzed. Epidemiological data confirm microplastic accumulation in human reproductive tissues, which correlates with declining semen quality. Experimental evidence reveals that microplastics penetrate the blood-testis barrier to trigger testicular oxidative stress, DNA damage and epigenetic dysregulation, further causing inflammation, barrier disruption, hormone imbalance and sustained spermatogenic injury. This review systematically interprets core toxic cascades of microplastic-induced male infertility, and compares heterogeneous reproductive toxicity from varying particle sizes, polymers, doses and combined pollutants. Research gaps and future directions are also outlined, providing theoretical support for assessing male reproductive hazards of microplastic pollution.