Integrated toxicological approach to microplastics and nanoplastics in crustaceans

Microplastics (MPs) and nanoplastics (NPs) have emerged as pervasive contaminants in aquatic ecosystems, with global inputs to the oceans projected to rise from 11 million metric tons in 2016 to 44 million tons by 2060. Originating from single-use plastics, textiles, fishing gear, industrial waste, and other sources, these particles enter water bodies via urban runoff, wastewater effluents, and atmospheric deposition, ultimately accumulating in sediments. Crustaceans, due to their benthic foraging behavior, wide ecological distribution, and trophic relevance, are highly susceptible to MP/NP exposure and serve as effective bioindicators of plastic pollution. This review synthesizes current knowledge on the occurrence, bioaccumulation, and multifaceted toxicological impacts of MPs and NPs in crustaceans. Evidence confirms uptake through ingestion, gill filtration, and dermal contact (primarily during the molting period), leading to biodistribution in the hepatopancreas, gut, gills, and hemolymph, even in edible tissues. Exposure triggers a broad range of sublethal effects, progressing from physical obstruction and cellular-level damage (oxidative stress, DNA damage, and histopathological lesions) to physiological disruptions (immune suppression, gut microbiome dysbiosis, endocrine disruption, osmoregulatory dysfunction, metabolic imbalance, and impaired growth and molting), and ultimately manifesting as behavioral alterations and reproductive disorders. Critically, the toxicity of MPs/NPs is often exacerbated by co-exposure to environmental stressors such as heavy metals, pesticides, pharmaceuticals, and other pollutants, with plastics acting as vectors that enhance contaminant bioavailability. Despite growing research, significant gaps remain in standardized methodologies, long-term monitoring, and understanding of trophic transfer, particularly in freshwater and aquaculture settings. This review emphasizes the urgent need for integrated risk assessment frameworks that account for particle characteristics, environmental variables, and multi-stressor interactions to safeguard aquatic ecosystems and the services they provide.