Ecotoxicological and Health Impacts of Micro- and Nanoplastics

Microplastics (MPs; <5 mm) and nanoplastics (NPs; <1 µm) have emerged as pervasive and persistent contaminants in aquatic ecosystems, posing significant risks to both environmental and human health. This chapter critically explores the ecotoxicological mechanisms and biological consequences of MPs/NPs across multiple levels of biological organization. Key factors such as particle size, polymer type, surface properties, and environmental weathering play crucial roles in determining their bioavailability, transport, and toxicity. MPs and NPs have been shown to induce oxidative stress, inflammation, genotoxicity, endocrine disruption, and neurotoxicity in aquatic organisms, with detrimental effects on reproduction, development, and behavior. These effects cascade through trophic levels, potentially altering ecosystem stability and function. A major emerging concern is the formation of the plastisphere, a dynamic microbial community on plastic surfaces that serves as a reservoir for pathogens and antibiotic resistance genes. This plastisphere contributes to the horizontal gene transfer of resistance traits and may facilitate disease emergence, thus bridging ecological and public health risks. Humans are increasingly exposed to MPs/NPs through seafood consumption, drinking water, inhalation, and occupational contact. While epidemiological data remain limited, and studies suggest possible links to inflammation, immune dysregulation, reproductive toxicity, and gut microbiome disturbances. This chapter also identifies critical knowledge gaps in current ecotoxicological and human health assessments, emphasizing the need for standardized methodologies, interdisciplinary collaboration, and regulatory integration. Advancing our understanding of MPs/NPs is essential for mitigating risks, guiding sustainable plastic use, and informing international environmental and public health policies.