Introduction to Microplastics: Origin, Environmental Pathways, and Impacts on Ecosystems and Human Health

Abstract

The plastics which were valued for their durability and versatility, have become ubiquitous in modern applications, from packaging to medicine. However, their non-biodegradable nature and poor waste management have led to severe environmental pollution, with over 430 million tons produced annually, which is projected to double by 2040. The improper disposal of such a huge plastic waste results in the release and accumulation of microplastics (MPs, < 5 mm) and nanoplastics (NPs, < 100 nm) in air, water, soil, and biota, which is being produced from both intentional production and degradation of larger plastics. These persistent MPs contaminate the various ecosystems, enter into the food chains through ingestion, inhalation, and dermal contact, and act as vectors for several toxic chemicals like heavy metals and polycyclic aromatic hydrocarbons, and increase their ecological and health impacts. In aquatic systems, MPs cause physical harm through ingestion and entanglement and reduces the growth and survival of organisms. In terrestrial environments, MPs disrupt soil structure, microbial activity, and nutrient cycling and impairs the health of plants. Human exposure to MPs is linked to respiratory, immune, and reproductive health issues, exacerbated by toxic additives like phthalates and flame retardants. The current chapter explores the sources, pathways, and impacts of MPs and NPs, emphasizing the urgent need for improved waste management, biodegradable alternatives, and global cooperation to mitigate plastic pollution and safeguard ecosystems and human health. © 2025 The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Switzerland AG.