Different types of nanoplastics exert varying degrees of toxicity on human sperm at semen-related concentrations

Previous research on the toxicity of nanoplastics (NPs) on male reproduction have centered on polystyrene (PS), a diverse range of NPs types has been identified in human semen and testes, warranting further investigation. In the present study, we employed pyrolysis gas chromatography-mass spectrometry (Py-GCMS) to quantify the presence of multiple NPs in human semen. Subsequently, we assessed the impact of various NPs at semen-related concentrations on human sperm functions and physiological parameters. Polypropylene (PP, 0.19-33.85 μg/mL), polyethylene (PE, 3.53-865.55 μg/mL), and polyethylene terephthalate (PET, 305.74 μg/mL) were detected in human semen. Exposure to PE at concentrations of 0.5 and 1 mg/mL significantly reduced sperm viability, motility, penetration ability, and mitochondrial membrane potential (MMP), while also inducing oxidative stress. At 1 mg/mL, PET decreased sperm motility, penetration ability and MMP, though it did not affect viability or reactive oxygen species (ROS) levels. In contrast, PP exhibited no adverse effects on sperm functions and physiological parameters at semen-related concentrations. Our findings demonstrate that different types of NPs exert varying degrees of toxicity on human sperm at semen-related concentrations, with PE exhibiting the highest toxicity and PP showing no observable toxicity. Moreover, exposure to mixture of NPs more accurately reflects human daily exposure scenarios. We evaluated the effects of mixed NPs on sperm function and observed that, with increasing co-incubation time, the NPs mixture induced more pronounced impairments in sperm viability and other parameters compared to exposure to any single type of NPs.