Micro- and nanoplastics-induced oocyte toxicity: molecular mechanisms and potential intergenerational and transgenerational risks

Micro- and nanoplastics (MNPs) are widely distributed and persistent in the environment. They can enter the body through ingestion, inhalation, and dermal contact, and their potential effects on female reproductive health have drawn increasing attention. Oocytes are central to female reproductive function. However, the mechanisms underlying MNP toxicity to oocytes, as well as their intergenerational and transgenerational effects, remain poorly understood. This review searched databases such as PubMed and Web of Science. By integrating evidence from diverse animal models and human samples, it summarizes the potential effects of MNPs on oocytes and the related molecular mechanisms. The findings indicate that MNPs may impair oocyte development via oxidative stress, inflammation, endoplasmic reticulum stress, endocrine disruption, and epigenetic modifications. These processes are associated with changes in the Wnt/β-catenin, NOD-like receptor family pyrin domain containing 3 (NLRP3)/caspase-1, Toll-like receptor 4 (TLR4)/nuclear factor kappa B (NF-κB), and protein kinase R-like endoplasmic reticulum kinase (PERK)/eukaryotic initiation factor 2 alpha (eIF2α) signaling pathways, and are linked to mitochondrial dysfunction, apoptosis, meiotic defects, chromosomal abnormalities, and impaired oocyte maturation. Animal studies further suggest that maternal exposure to MNPs may impair offspring development and reproductive function. However, evidence for true transgenerational effects remains limited. Notably, most existing evidence comes from animal studies, many of which used standardized polystyrene (PS) particles. Although MNPs have been detected in human biological samples, their actual effects on human reproductive health remain to be clarified.