The risk of micro/nanoplastics to human sperm and the intervention against their toxicity using magnetic Fe3O4 nanoparticles

Abstract Micro/nanoplastics (MNPs) are novel hazardous materials that pose multiple environmental challenges. Polystyrene (PS)-MNPs (especially those with sizes less than 10 µm) reduce male fertility in murine models. More importantly, microplastics contaminate male reproductive tissues, but whether MNPs truly affect male reproduction in humans is poorly understood. In this study, we aimed to evaluate the risk of human sperm exposure to NMPs and explore interventions for their toxicity. Using a coculture system, we exposed human sperm to synthetic PS-MNPs, environmental MNPs from disposable paper cups, and a combination of PS-MNPs and bisphenol A (a commonly used plastic additive). In addition, this study examined the ability of magnetic Fe 3 O 4 nanoparticles to prevent the toxicity of PS-MNPs to human sperm. The results showed that human semen contains approximately 3.6 µg/mL PS-MNPs with sizes less than 10 µm. PS-MNPs of 25–100 nm can penetrate human sperm, while those of 0.5–10 µm can bind to the sperm surface. Only 25-nm PS-NPs significantly affect human sperm functions and physiological parameters at semen-relevant concentration. The 25-nm PS-NPs also exhibited synergistic toxicity with bisphenol A on human sperm. However, environmental MNPs released from disposable paper cups do not pose a significant hazard to human sperm. Furthermore, magnetic Fe 3 O 4 nanoparticles could aggregate and coprecipitate with 25-nm PS-NPs to eliminate their adverse effects on human sperm. Here, we demonstrated the potential risk of PS-MNPs to male reproduction in humans and provided an effective intervention strategy against their toxicity.