Avaliação do potencial ecotoxicológico das nanofibras de carbono utilizando organismos do grupo dos invertebrados e vertebrados

Abstract

This thesis was divided into chapters, in which different objectives were pursued. In the first chapter, we look at the main ways in which carbon nanofibers are used, as well as the main forms of production and the most recent scientific work. In the second chapter, we tested the hypothesis that exposure to carbon nanofibers (CNFs) at environmental concentrations for a short period (48 h) causes biochemical disturbances predictive of oxidative stress, antioxidant deficit and neurotoxicity in dragonfly larvae (Aphylla williamsoni). Dragonflies belong to the order Odonata, which has one of the largest numbers of aquatic species ever cataloged, and has important ecological functions, such as population control of various other organisms. As far as we know, this chapter is the first study to report the impact of NFCs on a species belonging to this taxonomic order, providing an insight into the ecotoxicological risks that these pollutants pose to the fauna of benthic macroinvertebrates living in freshwater ecosystems. In the third chapter, we aimed to evaluate the possible effects of prolonged exposure (90 days) of juvenile zebrafish (Danio rerio) to different concentrations of NFCs. . The zebrafish is one of the freshwater fish most commonly used as an ecotoxicological model for nanomaterial-induced toxicity profiles and has important ecological functions in its natural environments, which justifies its choice as a model system in this work. We started from the hypothesis that even in small concentrations, when NFCs are ingested by animals, they induce behavioral changes, as well as changes in the density of mechanoreceptors called neuromasts (lateral line organs), in addition to brain biochemical changes, erythrocyte nuclear abnormalities, DNA damage and impaired animal growth/development. In the fourth chapter, we assess, for the first time, whether the exposure of Lumbricus terrestris earthworms naturally infected with Monocystis sp. to NFCs, at environmentally relevant concentrations, potentiates the parasitic infection and induces adverse effects on the animals' health. Earthworms provide various ecosystem services through pedogenesis, soil structure development, water regulation, nutrient cycling, primary production, climate regulation, pollution remediation and cultural services. We therefore believe that our study will contribute to understanding the ecotoxicological risks of NFCs for edaphic organisms. Finally, the chapter "Conclusions and final considerations" presents an overview of the ecotoxicity of the NFCs reported in this thesis, as well as shedding light on the fields of research in this area that can be better explored in the future.