Surface area of carbon-based nanoparticles prevails on dispersion for growth inhibition in amphibians

The attractive properties of carbon-based nanoparticles such as graphene and its derivatives or carbon nanotubes lead to their use in many application fields, whether they are raw or functionalized, such as oxidized. These particles may finally contaminate the aquatic compartment, which is a major receptacle of pollutants. The study of their impact on aquatic organisms is thus essential. At the nano scale, recent studies have highlighted that specific surface area should be used as the most relevant descriptor of toxicity instead of the conventional mass concentration. By using a dose-response model, this work compares the chronic toxicity observed on Xenopus laevis larvae after 12-day in vivo exposure to raw, oxidized carbon allotropes, or in the presence of chemical dispersant. We show that chemical dispersion does not influence the observed chronic toxicity, whether it is through surface chemistry (oxidation state) or through the addition of a dispersant. The biological hypothesis leading to growth inhibition are discussed. Finally, these results confirm that surface area is the more suited metric unit describing growth inhibition

Transfer and Ecotoxicity of Titanium Dioxide Nanoparticles in Terrestrial and Aquatic Ecosystems: A Microcosm Study

With the advancement in nanotechnology, particularly the use of TiO₂ nanoparticles (NPs), there is a need to study their release into the environment and assess the related risk in an environmentally relevant contamination scenario. In the present study, the transfer and toxicity of TiO₂ NPs in microcosms mimicking terrestrial and aquatic ecosystems were evaluated. The contaminated soil was prepared by spiking natural soils, with these then used as the basis for all exposure systems including preparation of soil leachates for amphibian exposure. Results demonstrated significant reductions in bacterial (−45%) and archaeal (−36%) nitrifier abundance; significant translocation of Ti to M. truncatula leaves (+422%); significant reductions in plant height (−17%), number of leaves (−29%), and aboveground biomass (−53%); nonsignificant Ti uptake in snail foot and viscera, and excretion in feces; and genotoxicity to X. laevis larvae (+119% micronuclei). Our study highlights a possible risk of engineered TiO₂ NPs in the environment in terms of trophic transfer and toxicity in both terrestrial and aquatic environments