Micropoluentes orgânicos emergentes na região amazônica: efeitos de concentrações ambientalmente realistas de ftalato em Hyphessobrycon heterorhabdus (Teleostei: Characidae)

Abstract

Emerging micropollutants (EMs) are any chemical products that are not part of environmental monitoring programs and are directly associated with anthropogenic activities. One example is phthalates, synthetic products widely used in the plasticizer industry. We can mention di-butyl phthalate (DBP), one of the most commonly found in the environment, which can cause effects such as genotoxicity, apoptosis, neurotoxicity, hepatoxicity, etc. Recent studies around the world have identified and quantified DBPs in the environment, investigating their impact on aquatic organisms. However, in Brazil, more specifically in the Amazon region, there are still no studies in this regard, leaving a gap in the presence of EMs in the aquatic environment and their effects on native species. Thus, the general objective of this dissertation was to identify and quantify EMs in urban rivers in the city of Belém, PA, Brazil, and to evaluate the oxidative stress responses of the species Hyphessobrycon heterorhabdus (Tetra Bandeira) to exposure to the highest concentration of DBP found in the region. The dissertation is structured into two chapters: I) a field study, in which EMs were identified and quantified in urban rivers in Belém, one of the most urbanized cities in the Eastern Amazon, and II) an experimental study, in which the biochemical changes in H. heterorhabdus exposed to three concentrations of DBP were evaluated. The field study collected samples from two urban rivers, the Tamandaré and Tucunduba canals. Water samples were collected in amber bottles, identified, and sent to the laboratory for quantification of EMs by liquid chromatography. The fish were obtained from the Parque Ecológico do Gunma and acclimatized in the laboratory for the experiment. The animals were exposed to three concentrations of DBP: (i) acetone control (CA); group 1 (G1): 10 μg/L; group 2 (G2): 100 μg/L and group 3 (G3): 1000 μg/L for seven days. Water samples were collected from all groups at specific times for the quantification of DBP in the experimental medium. The animals were dissected into anterior, middle, and posterior portions for biochemical analysis, such as total antioxidant capacity (ACAP), glutathione-S-transferase (GST) activity, and lipoperoxidation (LPO). Three groups of EMs were identified: organochlorines, polycyclic aromatic hydrocarbons (PAHs), and phthalates. Among the phthalates, DBP and di(2-ethylhexyl) phthalate (DEHP) were the EMs with the highest concentrations, at 10.428 μg/L and 7.547 μg/L, respectively. In the experimental study, ACAP did not vary among the groups in the anterior and posterior sections, while in the middle section, we observed a concentration-dependent effect. GST did not vary in the posterior section, but in the anterior section, there was an increase in GST in the G2 group and a decrease in G1 in the middle section. The LPO showed a concentration-dependent and hormetic effects in the anterior and posterior sections, respectively. In the middle section, the LPO did not vary among the groups. In general, we conclude that organochlorines, PAHs, and phthalates are present in the rivers studied and that exposure to DBP results in stress to the organisms tested. Furthermore, our results are of great relevance to the Amazon region, as this is a pioneering study.