The stealthy journey of nanoplastics in bivalves: accumulation dynamics and toxic burden

The strong filter-feeding capacity of bivalves makes them more prone to accumulating nanoplastic particles from their environment, posing a threat to aquaculture and food safety. Despite their inconspicuous size, nanoplastics embark on a stealthy invasion through bivalve tissues, evading conventional detection. Reliable detection methods for nanoplastics are essential for risk assessment. This paper provides a comprehensive review of nanoplastic detection techniques in biological tissues and suggests improvements in in situ detection and AI-based recognition methods. These advancements are critical to unveiling the hidden pathways of nanoplastics in biological systems. Next, we summarize the endocytic mechanisms and bioaccumulation patterns of nanoplastics based on particle size classification and realistic environmental scenarios, identifying gills and hepatopancreas as primary accumulation targets. This dynamic accumulation process highlights how nanoplastics progressively infiltrate key organs, escalating their toxic burden. Additionally, this paper offers a thorough overview of the pathways through which nanoplastics breach biological barriers and trigger cascading reactions, from cellular stress to organelle dysfunction, tissue damage, and ultimately organismal consequences. These cascading effects underscore the insidious yet pervasive toxic burden imposed by nanoplastics. Finally, this review identifies key research gaps, including the synergistic or inhibitory effects of coexisting marine pollutants on bivalve bioaccumulation and the unclear pathways and efficiency of nanoplastic accumulation in filter-feeding bivalves under eco-corona regulation. Unraveling these uncertainties is vital to mapping the full journey of nanoplastics and mitigating their ecological toll. This review aims to enhance the understanding of nanoplastic–bivalve interactions and guide mitigation strategies for their ecological effects.