Core Viewpoint - Microplastics and nanoplastics (MNPs) have emerged as significant environmental pollutants, raising concerns regarding their impact on ecological health and public well-being due to their microscopic size, widespread distribution, and resistance to degradation [2][3]. Group 1: Presence and Entry Pathways - Microplastics are found in various natural environments, including water sources, soil, air, and even within biological organisms [3]. - They can enter the human body through multiple pathways, such as the food chain, drinking water, air inhalation, and skin contact, making them a pervasive form of pollution [3][4]. Group 2: Toxicological Effects - Current research indicates that microplastics pose potential health risks, affecting multiple biological systems, including the nervous, urinary, and reproductive systems [6]. - Microplastics can induce oxidative stress, activate inflammatory responses, disrupt apoptosis and autophagy balance, and alter gene expression, leading to chronic inflammation, tissue damage, and metabolic disorders [6][17][18]. Group 3: Specific Systemic Impacts - **Nervous System**: Microplastics can cross the blood-brain barrier and accumulate in the brain, with concentrations significantly higher than in the liver and kidneys. This accumulation is linked to neurodegenerative diseases, such as Alzheimer's, potentially accelerating cognitive decline [8]. - **Urinary System**: Microplastics can accumulate in the kidneys, impairing their physiological functions and leading to chronic kidney diseases. They induce oxidative stress and activate inflammatory pathways, contributing to long-term health risks [10][11]. - **Reproductive System**: Exposure to polystyrene nanoparticles (PS-NP) during pregnancy has been shown to reduce testosterone levels and sperm quality in male offspring, indicating reproductive toxicity [13][14]. Group 4: Cellular Function Impact - Microplastics significantly affect cellular vitality, with studies showing that polystyrene nanoparticles can induce oxidative stress and apoptosis in both cancerous and normal cells, highlighting their specific toxicity [16][17]. Group 5: Future Research Directions - There is a pressing need to assess the long-term health impacts of microplastics due to their persistence in the environment and accumulation in biological systems. Establishing long-term tracking cohorts and health monitoring systems is essential for understanding the relationship between microplastic exposure and various diseases [20]. - Research should also focus on the synergistic effects of microplastics with other environmental pollutants, such as heavy metals and persistent organic pollutants, to understand their combined toxicological impacts [21].