Environmental Fate, Plastisphere Microbial Dynamics, and Human Health Implications of Marine Micro- and Nanoplastics

Abstract

Micro- and nanoplastics are now widely recognized as contaminants of marine environments, with increasing concern about their potential effects on ecological and human health. Due to their small size, persistence, and high surface-area-to-volume ratio, these particles can interact with a large number of matrices in the environment and biological systems. Plastic particles quickly get covered by various microbial communities in water bodies to form complex structures known collectively as the plastisphere. These assemblages of microbes may influence how plastics behave in the environment and could help transport microorganisms and chemical contaminants across marine ecosystems. This review summarizes what is known about where micro- and nanoplastics are found in the environment, how they interact with microbial communities, and what their ecological and toxicological effects are. More detail is provided about the formation of plastispheres, the succession of microbes on plastic surfaces, plastic particles as vectors for pathogens and toxic substances. The review also looks at new evidence that links exposure to microplastics with oxidative stress, inflammatory responses, endocrine disruption, and changes in gut microbial communities in aquatic organisms—and perhaps even in humans. Finally, it discusses new developments and analytical challenges related to the detection and characterization of micro- and nanoplastics from environmental samples. Though substantial progress has been made, there are still significant knowledge gaps regarding standardized analytical methods for chronic exposure thresholds as well as mechanistic toxicology for nanoplastics. Overcoming these challenges through interdisciplinary research and enhanced environmental monitoring will be critical for improving risk assessment efforts aimed at reducing plastic pollution in marine ecosystems.