Micro-nanoplastics in the central nervous system: Evidence, mechanisms and perspectives

Environmental exposure to micro-nanoplastics (MNPs) has emerged as a significant concern for neurological health. This review synthesizes evidence that MNPs translocate the blood-brain barrier (BBB) and induce neurotoxicity through mechanisms including oxidative stress, neuroinflammation, mitochondrial dysfunction, and neurotransmitter disruption. In rodent models, these disturbances lead to pathological and behavioral deficits relevant to neurodegeneration, neurodevelopmental disorders, and psychiatric conditions. Critically, we evaluate emerging clinical studies confirming the presence of MNPs within human central nervous system tissues and fluids. Our review then provides a critical appraisal of these human studies, highlighting their methodological limitations and inconsistent application of quality assurance/quality control (QA/QC) protocols, which currently constrain robust exposure assessment and causal inference. While clinical correlations exist between MNP levels and markers of BBB integrity, cognitive function, and stroke severity, establishing causality requires standardized detection methods and rigorous QA/QC integrated with longitudinal cohort studies. Generating such reliable evidence is paramount for informing public health strategies aimed at mitigating plastic exposure.