Genotoxicidade do efluente têxtil em células hepáticas e sanguíneas de Rhamdia quelen (Pisces, Siluriforme) através do ensaio cometa

Abstract

Textile industries have been growing gradually, generating jobs and rotating the socioeconomic sector. However, they are also among the largest generators of polluting waste. The textile effluent is generated in large volumes and with high doses of dyes and other toxic substances. It is a complex residue, difficult to degrade, containing xenobiotic, recalcitrant and toxic substances. When in contact with water bodies without proper treatment, these compounds can cause damage to the health of aquatic biota and trigger various environmental impacts. The present study aims to analyze the genotoxicity of textile effluent in its raw composition and treated on the bioindicator Rhamdia quelen. For that, preliminary tests were carried out to determine the lethal concentration. Subsequently, 180 specimens of R. quelen were subchronically submitted to concentrations of 0% (control); 1,25%; 2,5%; 5%; 7,5% and 10% (in triplicates) of the raw and treated effluent from a textile industry. Animals of both sexes were divided into 18 boxes of 60 liters. The exposure was for seven days under controlled conditions. At the end of the experimental period, blood and liver tissue were collected from the individuals. These samples were subjected to the single cell gel electrophoresis test, commonly known as the comet assay. This technique was used because it is considered sensitive, simple and fast to analyze possible genotoxic damage. The slides were stained with ethidium bromide and the analyzes were performed with fluorescence microscopy. 100 nucleoids/slide were analyzed, following damage counts from 0 (no damage) to damage 4 (cellular apoptosis). With the analysis of the data, it can be observed that there was no significant difference between the dilutions of the raw and treated effluent compared to the control. In erythrocytes, the raw effluent caused significantly greater damage than the treated effluent as expected. In hepatocytes, the damages were not significant raw and treated effluents. With this work, it is concluded that the raw effluent causes genotoxic damage at low concentrations in short periods, while the treated effluent proved to be safe at a concentration of 10% for up to seven days.