A perspective on the potential impact of microplastics and nanoplastics on the human central nervous system

Humans are constantly exposed to microplastics and nanoplastics (MNPs). Although significant gaps remain in our understanding of their adverse effects on human health, it is increasingly evident that MNPs can penetrate physiological barriers and accumulate in various locations within the human body. Analytical limitations in tracking and measuring nanoplastics in physiological media may persist for several years before we can accurately detect these particles in the human body and establish a clear link between exposure to them and associated hazards. In addition to the few studies that have emerged recently, our knowledge of chemicals with properties similar to those of MNPs, as well as other types of nanomaterials, suggests that MNPs may cross the blood–brain barrier (BBB) and potentially induce damage to the human central nervous system. Here, we provide an overview of the limited number of studies available on this topic and present a perspective on the potential pathways through which MNPs may penetrate the BBB. We also discuss the main mechanisms by which MNPs could potentially impact the central nervous system (CNS), with a focus on neurodegenerative diseases such as Alzheimer's disease (AD), Parkinson's disease (PD), multiple sclerosis (MS), and amyotrophic lateral sclerosis (ALS). This information could contribute to the development of tailored studies exploring the negative effects of MNPs on the CNS.