Avaliação de resíduos oleosos biorremediados: embriotoxicidade, neurotoxicidade e estresse oxidativo em zebrafish

Abstract

Increasing environmental pollution, particularly the contamination of aquatic ecosystems by industrial oily waste, poses a challenge to public health and ecological sustainability. The release of waste oils, rich in hydrocarbons, heavy metals and other toxic substances, causes degradation of water quality, impacts on biota and direct risks to human health. Given the limitations of conventional treatment methods, bioremediation emerges as a promising, sustainable and economically viable technology to mitigate this contamination. This study evaluated the efficacy of a bacterial consortium in the bioremediation of oily waste and its ecotoxicological effects on Danio rerio (zebrafish). Embryotoxicity tests were conducted with different concentrations of raw and bioremediated oily waste, in the period from 4 to 120 hours post-fertilization (hpf). At seven days, the larvae were subjected to neurobehavioral analysis (optomotor response), quantification of reactive oxygen species (ROS) and evaluation of gene expression by qPCR, focusing on markers of oxidative stress, inflammation and neuroplasticity. The results indicated that the crude residue presented toxicity inversely proportional to dilution, while the effects of the bioremediated residue did not follow a dose-dependent pattern. Only the crude oil demonstrated a statistically significant difference in the Reactive Oxygen Species (ROS) tests when compared to the control group. However, no other statistically significant differences were observed in the ROS and optomotor response tests between the other treated groups and the negative control. Furthermore, a significant change in the expression of the IL-1β gene was observed in both exposed groups, indicating an inflammatory response even in the absence of apparent neurotoxicity. Bioremediation, together with dilution/dispersion, is crucial to mitigate the toxic effects of these residues in small-volume aquatic environments.