TRANSFERÊNCIA TRÓFICA DE NANOFIBRAS DE CARBONO ENTRE Eisenia fetida, Danio rerio e Oreochromis niloticus E SUA TOXICIDADE NO ÚLTIMO NÍVEL TRÓFICO

Abstract

Although the toxicity of carbon-based nanomaterials has already been demonstrated, their transfer in the food chains, as well as their impact on the upper trophic level, is an unexplored theme. Thus, from the experimental food chain “Eisenia fetida → Danio rerio → Oreochromis niloticus” we tested the hypothesis that carbon nanofibers (CNFs) accumulate in animals, are transferred to the upper trophic level, causing mutagenic and cytotoxic changes. For this porpose, E. fetida were exposed to CNFs (for 7 days) and then they were offered to D. rerio (for 48 h), which subsequently served as food for O. niloticus (also for 48 h). The quantification of total organic carbon provided evidence of the accumulation of CNFs at all trophic levels evaluated, suggesting their absorption and translocation via the hepatic portal system. In tilapia exposed to CNFs via the food chain, this accumulation was associated with a higher frequency of erythrocyte nuclear abnormalities, such as constricted erythrocyte nuclei, vacuole, blebbed, kidney-shaped and micronucleated erythrocytes. The frequency of binucleated erythrocytes and displaced nuclei did not differ between tilapia fed with D. rerio exposed directly to CNFs and those that ingested D. rerio previously fed with contaminated earthworms. In addition, the pollutants' cytotoxicity was inferred by the smaller size of the erythrocyte nuclei and the lower “nuclear/cytoplasmic” area ratio in tilapia exposed to CNFs via the food chain. In this segment, we confirm the initial hypothesis, providing pioneering evidence of the accumulation of CNFs in the trophic levels of the experimental food chain, as well as the mutagenic and cytotoxic effect of these materials in O. niloticus.