Brain under siege: the role of micro and nanoplastics in neuroinflammation and oxidative stress

The widespread occurrence of microplastics (MPs) and nanoplastics (NPs) in the environment has spurred rising concerns over their health risks, notably concerning harm to the central nervous system. Due to their small size, MPs and NPs can migrate across biological barriers, such as the blood-brain barrier, accumulating in nervous tissue. Overall, emerging evidence suggests that these particles behave as neurotoxicants leading to oxidative stress, neuroinflammation, and synaptic pathological changes. This review summarizes our understanding of the neurotoxic effects of MPs and NPs, with specific focuses on bioaccumulation, generation of reactive oxygen species, microglia and astrocyte activation, inflammatory signaling pathways, and opportunities for chronic plastic exposure to mediate neurodegenerative and neurodevelopmental disorders. The current review integrates mechanistic work described from in vitro, in vivo, and limited human studies to summarize important mechanistic information and expose gaps in our present understanding related to the long-term neurological consequences of plastic exposure. This review provides urgent evidence for the need to conduct interdisciplinary research toward development of policy to mitigate the neurotoxic burden of environmental plastics, while also acknowledging current limitations in experimental models, human data, and exposure assessment, and highlighting future prospects for advancing mechanistic insights, translational research, and preventive strategies.