Biological uptake, distribution and toxicity of micro(nano)plastics in the aquatic biota: A special emphasis on size-dependent impacts

Microplastics (MPs) and nanoplastics (NPs), defined as plastic particles smaller than 5 mm and 100 nm, respectively, have emerged as significantly hazardous contaminants in global environments. These particles originate from various sources, including industrial products, consumer goods, and the degradation of larger plastic debris. Micro (nano)plastics (MNPs) have become ubiquitous contaminants in aquatic ecosystems, raising concerns about their uptake and distribution within aquatic biota and their potential ecological impacts. This review presents a comprehensive overview of the transfer and hazards of MNPs in aquatic environments, with a focus on their toxicity to aquatic organisms, including size-dependent effects, tissue distribution within organisms, and trophic transfer along the food chain. Once ingested, MNPs can distribute within the organs and tissues, such as gastrointestinal tract, gills, liver, among others. Moreover, the ingestion of MNPs by primary consumers can lead to their transfer along the food chain, potentially causing bioaccumulation and biomagnification. The presence of MNPs poses significant risks to aquatic organisms, affecting their survival, growth, reproduction, and behavior. The size of particles plays a crucial role, with smaller particles often exhibiting more pronounced toxic effects. Understanding these aspects is essential for addressing the ecological consequences of plastic pollution and developing effective mitigation strategies.