Advances in Male Reproductive Toxicology of Nanoplastics: Potential Risks to Human Reproduction—A Systematic Review

Microplastics and nanoplastics (MPs/NPs) have emerged as pervasive and persistent environmental contaminants, prompting significant concerns about their potential risks to human health. This review provides a comprehensive synthesis of the current state of knowledge on the reproductive toxicity induced by MPs/NPs, with a particular focus on nanoplastics (NPs, <100 nm) due to their enhanced ability to cross biological barriers and induce cellular damage. Following a systematic literature search, we detail the multiple exposure pathways-including ingestion, inhalation, and dermal contact-through which MPs/NPs enter the human body and are disseminated to reproductive tissues. The core of this review elucidates the fundamental mechanisms underlying MPs/NPs-induced reproductive damage. Compelling evidence from in vitro, animal, and initial human studies demonstrates that MP/NP exposure can lead to diminished sperm quality and motility, testicular histological disruption, impaired ovarian folliculogenesis, granulosa cell apoptosis, and dysregulation of key reproductive hormones. We further summarize potential therapeutic interventions, such as antioxidants and traditional Chinese medicine compounds, and discuss key preventive and regulatory strategies. Despite the advancing evidence, critical challenges remain, including quantifying actual human exposure levels, understanding the effects of chronic, low-dose exposure, and elucidating the combined toxicity of MPs/NPs with other environmental pollutants. This comprehensive analysis underscores the urgent need for further mechanistic research, robust epidemiological studies, and the formulation of evidence-based public health policies to mitigate exposure and safeguard global reproductive health.