Reproductive toxicity and transgenerational effects of microplastics: Evidence from experimental models and underlying epigenetic mechanisms.

Micro- and nanoplastics (MNPs) are emerging environmental contaminants with ubiquitous distribution and growing concern for reproductive health. Recent detection of MNPs in human follicular fluid and seminal plasma suggests that these particles can enter the reproductive microenvironment and interfere with gametogenesis and reproductive function in both females and males. On the basis of summarizing the toxic effects of MNPs on the male and female reproductive systems, this review focuses on their potential impacts on offspring and subsequent generations. Current evidence suggests that MNPs compromise male and female reproductive function by disrupting gametogenesis, endocrine regulation, mitochondrial activity, and reproductive tissue homeostasis. Animal studies further show that parental exposure to MNPs can adversely affect unexposed descendants, leading to persistent abnormalities in growth and development, reproductive capacity, metabolic homeostasis, neurobehavior, immune regulation, and multi-organ function. Mechanistically, aberrant DNA methylation, altered histone modifications, and dysregulation of non-coding RNAs, including miRNAs, tsRNAs, and rsRNAs, are considered major epigenetic mechanisms underlying the intergenerational and transgenerational toxicity of MNPs. Collectively, these findings suggest that MNPs not only impair reproductive function in exposed individuals but may also exert long-term effects on descendant health through germline epigenetic reprogramming. Further studies in mammalian models and human populations are needed to clarify the true patterns of transgenerational transmission and the underlying molecular mechanisms, thereby improving the assessment of the reproductive and developmental risks associated with MNPs exposure.