Avaliação ecotoxicológica de microplástico de polietileno e sua interação com o herbicida 2,4-D utilizando o bioindicador Girardia tigrina

Abstract

Water sources around agricultural areas are highly exposed to pesticide contamination. The most commonly used classes of pesticides include herbicides, especially 2,4- dichlorophenoxyacetic acid (2,4-D), the second most widely used herbicide in Brazil. In addition to pesticides, the presence of microplastics (MP) in the aquatic environment has also been reported in various parts of the world. In Brazilian rivers, both contaminants were found in high concentrations, implying a high probability of their association, which may alter their individual effects and potentially increase their toxicity. The study interactions between herbicides, microplastics and freshwater organisms is essential for understanding the dynamics of aquatic ecosystems and thus for predicting their potential impacts. Therefore, in this work, both the isolated effect of polyethylene microplastics (MP-PE) and the combined effect of MP- PE with the herbicide 2,4-D were investigated, using planarians of the species Girardia tigrina as bioindicator. The results were divided into two chapters: “Behavioral and physiological responses of G. tigrina exposed to polyethylene microplastics” and “Interaction between polyethylene microplastics and 2,4-D: chemical and ecotoxicological assessment with G. tigrina”, describing the behavioral responses (locomotion) and physiological responses (regeneration and reproduction) responses of the planarians. In the first chapter, pure MP-PE was evaluated, and it was found that under this condition there was a reduction in the regeneration of the blastema, photoreceptors and auricles of the planarians. In Chapter 2, the ecotoxicity of treated MP-PE and treated MP-PE + 2,4-D was investigated, and changes in planarian locomotion, regeneration and reproduction were observed. In addition, the interaction of treated MP-PE + 2,4-D show greater toxicity compared to treated MP-PE in all parameters evaluatedIn general, both studies for assessing the impact of MP-PE on the environment and show that there is a possibility that this pollutant transports other pollutants and increases its ecotoxicity.