Effects of nanoplastics on clam Ruditapes philippinarum at environmentally realistic concentrations: Toxicokinetics, toxicity, and gut microbiota

Nanoplastics are ubiquitous in marine environments, understanding to what extent nanoplastics accumulate in bivalves and the adverse effects derived from their retention is imperative for evaluating the detrimental effects in the benthic ecosystem. Here, using palladium-doped polystyrene nanoplastics (139.5 nm, 43.8 mV), we quantitatively determined nanoplastic accumulation in Ruditapes philippinarum and investigated its toxic effects by combining physiological damage assessments with a toxicokinetic model and 16 S rRNA sequencing. After a 14 days exposure, significant nanoplastic accumulation was observed, up to 17.2 and 137.9 mg center dot kg (-1) for the environmentally realistic (0.02 mg center dot L (-1)) and ecologically (2 mg center dot L (-1)) relevant groups, respectively. Ecologically relevant nanoplastic concentrations evidently attenuated the total antioxidant capacity and stimulated excessive reactive oxygen species, which elicited lipid peroxidation, apoptosis, and pathological damage. The modeled uptake (k(1)) and elimination (k(2)) rate constants (from physiologically based pharmacokinetic model) were significantly negatively correlated with short-term toxicity. Although no obvious toxic effects were found,environmentally realistic exposures notably altered the intestinal microbial community structure. This workincreases our understanding of how the accumulation of nanoplastics influences their toxic effects in terms of the toxicokinetics and gut microbiota, providing further evidence of their potential environmental risks.

Automated summary

Nanoplastics are widely present in marine environments, with accumulation in bivalves having detrimental effects on the ecosystem. This study determined the accumulation of palladium-doped polystyrene nanoplastics in Ruditapes philippinarum and investigated its toxic effects using physiological damage assessments, a toxicokinetic model, and 16S rRNA sequencing. Significant nanoplastic accumulation was observed, leading to oxidative stress, apoptosis, and pathological damage. The study also found alterations in the intestinal microbial community structure. Overall, this work enhances our understanding of the toxic effects and environmental risks associated with nanoplastic accumulation.