Nanoplastics in the Biological System: A Microscopic Menace with an Impact

Nanoplastics, ultra-small polymer particles measuring less than one micrometre, have become a widespread and mostly invisible environmental pollutant with significant biological consequences due to their high surface activity, mobility, and capacity to traverse biological barriers. Nanoplastics, on the other hand, can easily move through air, water, soil, and living things, which means that everyone is exposed to them. This is not the case with macro- and microplastics, which are usually only found in certain places. This chapter examines their origins, physicochemical characteristics, environmental dispersion, and biological impacts, emphasising their interactions within living organisms. Experimental results from cellular and animal studies indicate that nanoplastics induce oxidative imbalance, mitochondrial dysfunction, lysosomal disruption, inflammatory signalling, and cellular apoptosis across various biological systems, including neural, immune, reproductive, and epithelial tissues. Animal studies show more evidence of placental transfer, foetal accumulation, metabolic dysfunction, and long-lasting effects on brain development, which raises concerns about effects that could last for generations. Direct evidence of human exposure has been established by the identification of nanoplastics in organs and biological fluids, including blood, breast milk, brain tissue, and the placenta, suggesting systemic distribution via ingestion, inhalation, and dermal pathways. Nanoplastics are even more toxic because they actively bind to and carry dangerous substances like heavy metals and persistent organic pollutants, which makes cellular damage worse by delivering contaminants together. Even though there is more and more evidence that plastic is bad for the environment, rules still mostly only apply to bigger plastic items. This chapter discusses the limits of analysis, looks at recent advances in detection, and points out major gaps in our knowledge about long-term exposure and environmental change. It stresses the need for more focused research and government action.