The use of ecotoxicity and genotoxicity biomarkers to evaluate the effects of pollution on environmental and human health through the application of in vivo and in vitro studies

Abstract

The contamination of air, water, and soil by harmful substances has become one of the most pressing global challenges. The discharge of effluents into rivers, for example, is a major environmental concern, since pollutants are released into water bodies, often from industrial, agricultural, and urban activities. When these effluents are not properly treated, they can introduce hazardous substances, including heavy metals, pharmaceuticals, Polycyclic Aromatic Hydrocarbons (PAH), and several other chemicals into the environment, or enter the food chain, posing a risk to both aquatic life and humans who rely on the river for drinking water, food, and recreation even in small concentrations. Thus, in the first experimental study (Part 1) we compared water-sediment samples collected in high-anthropogenic urban area and low-anthropogenic peri-urban area. We have used physicochemical parameters, genotoxicity assay, bioindication and acute and surviving chronic toxicity tests using Daphnia magna as organism model in an integrated biological assessment. Results suggest no acute toxicity related to exposure to samples from both areas. Still, samples collected in the high-anthropogenic urban area were associated with chronic toxicity effects in D. magna. Heavy metals Pb, Cu, and Cr were found in all samples. The Water Quality Index (WQI) score showed us that samples from high-anthropogenic sites were identified as “Poor,” and samples from low-anthropogenic sites were identified as “Good.” Ephemeroptera, Plecoptera, and Odonata, which are very sensitive organisms, were largely absent in high-anthropogenic areas, showing that it is likely to be associated with WQI. These results suggest that to protect water resources, aquatic life and human health, it is crucial to implement more efficient wastewater treatment processes and stricter regulations on industrial discharge. In the second experimental study (Part 2), we aimed to establish a protocol for the use of Zebrafish (Danio rerio) as a model of environmental chemical exposure and genotoxicity, using two different diets containing Benzo[a]pyrene (B[a]P), which is frequently found either on food or water, and can directly or indirectly damage DNA, causing alterations on gene expression, leading to mutations and cancer. While its effects are often discussed in ecological or medical terms, molecular biology also offers critical insights into how pollutants affect life at the cellular and genetic levels. Therefore, this study aimed to comprehend how this chemical can lead to the development of several human diseases using Zebrafish (Danio rerio) as an important model of genotoxicity, and disease, evaluating the alterations in the expression of the genes cyp1a, gclc, ephx1. Rpl13a was used as a reference gene. In general, the significant results showed that fish fed with a high carb diet containing B[a]P have an increased expression of cyp1a, gclc, and ephx1. Considering differences among sexes, the females ones have a higher expression of gclc and ephx1 if compared to male ones. These results suggest the high carb diet (HC) has proved to induce the upregulation, and consequently a higher inflammation process, more than the low carb diet in all the statistically significant results. In conclusion, both studies, if combined, could lead to innovative methods of environmental damage assessment, either through biotechnology or ecological assesment.