Ecotoxicological assessment of a graphene-based commercial ink toward freshwater ecosystems: From single-species tests to a microcosm approach
Résumé
The growing use of nanomaterials, including few-layer graphene (FLG) under various forms such as inks, raise concerns about their potential ecological impacts. This study evaluates the ecotoxicity on the aquatic compartment of a commercial ink composed of FLG stabilized with sodium deoxycholate (SDC) at a concentration of 1 g/L, through single-species bioassays and microcosm approaches on various aquatic organisms. The algae Raphidocelis subcapitata, the crustacean Daphnia magna, and the amphibian larvae Xenopus laevis were exposed to 0; 0.1; 10 and 50 mg/L of ink or SDC alone. The microcosm study was conducted with the ink or SDC at 0.1 mg/L, focusing on biofilm (diatoms and bacterial consortium) integrity and life-history traits of the dipteran Chironomus riparius. Results showed that although the ink exhibited weak toxicity in single-species bioassays or in microcosms, SDC alone caused significant toxic effects, depending on the biological model and concentration. Cellular alterations were observed in algae exposed to 0.1 mg/L of SDC, while acute toxicity occurred at concentrations over 50 mg/L in daphnia. Growth inhibition was observed in amphibian larvae at 0.1 and 1 mg/L without genotoxic effect. Microcosm study revealed slight changes in biofilm diversity and inhibition of chironomid growth by SDC (0.1 mg/L). This study highlights the importance of comprehensive ecological risk assessments for graphene-based materials and associated co-contaminants, emphasizing the environmental risks posed by SDC. The findings demonstrate the value of realistic approaches to evaluate the hazards of these chemicals and suggest that their release into the aquatic environments could pose significant ecological threats.
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