Avaliação da Toxicidade do Microplástico Polietileno em Conjunto com Distintos Poluentes Emergentes em Vertebrados Aquáticos

Abstract

The growing presence of microplastics (fragments <5mm) has generated global concerns due to their potential impact on human health and the environment. These small emerging pollutants can associate with other contaminants, such as metals and pesticides, increasing their toxicity and causing more serious effects. An analysis of the current state of scientific knowledge up to 2020 revealed that most studies on the toxicity of microplastics in amphibians are concentrated in Brazil, Italy, and China, with an emphasis on the order Anura. From this analysis, important recommendations emerged, such as the need to expand the diversity of species studied, evaluate the sensitivity of species considering the micro and nano size of particles, investigate the contributions of microplastics to the intensification of the effects caused by environmental stressors and explore the effects of plastic particles in association with other pollutants, since these pollutants are rarely isolated in the environment. To address some of these gaps, this thesis evaluated the possible effects of exposure of tadpoles of the species Physalaemus cuvieri and adults of Danio rerio, both in isolated exposure to microplastics and in association with different chemical compounds [i.e., pharmaceuticals, agro-industrial waste, hydrocarbons, synthetic hormones, fertilizers, pesticides, among others] in environmentally relevant concentrations. After exposing the specimens, the uptake and accumulation of microplastics, in addition to several biomarkers, were analyzed. In P. cuvieri tadpoles, morphological, biometric, and developmental indices, behavioral parameters, mutagenicity, cytotoxicity, antioxidant, and cholinesterase responses were investigated. In adults of Danio rerio, biomarkers of genotoxicity, mutagenicity and redox imbalance were analyzed. The results indicated notable changes in the physiological and biochemical patterns of the species evaluated [imbalance of pro-antioxidant activities – inferred by the levels of nitrite, superoxide dismutase and catalase, for example], in addition to confirming the translocation of these particles into the animals. This scenario highlights the potential adverse effects resulting from the presence of various pollutants in freshwater ecosystems