Evaluación De Los Efectos Citotóxicos y Genotóxicos Del Agua Del Rio Pamplonita En Células Meristemáticas De Allium cepa.

Abstract

The increasing pollution of urban rivers, such as the Pamplonita River in Pamplona (Norte de Santander), due to factors such as unorganized growth, inadequate sanitary waste management, and sewage discharges, represents an environmental and public health problem. Given this scenario, the main objective of this study was to evaluate the cytotoxic and genotoxic effects of Pamplonita River water on the root meristems of Allium cepa. To this end, the Allium cepa bioassay was used, a plant known for its sensitivity to environmental and industrial toxins. The root meristems of the bulbs were exposed to water samples T1 (river water) collected from three different areas of the river for 72 hours, comparing the results with T2, the positive control (ethylmethanesulfonate, EMS), and T3, the negative control (distilled water). Biological assessments included the mitotic index (MI), phase index (PI), chromosome abnormality index (CI), and root length. These analyses were complemented by the determination of physicochemical parameters (pH, conductivity, turbidity, color, total suspended solids (TSS), chemical oxygen demand (COD), and biochemical oxygen demand (BOD5), comparing their values with current Colombian environmental regulations. The results revealed that, while the mitotic index did not show a significant reduction compared to the negative control, significant effects were observed on the mitotic phase pattern. Specifically, the T2 treatment (positive control) caused an evident mitotic block in prophase, reaching 93.88 ± 8.47% in Zone 2 and demonstrating a statistically significant difference compared to the other phases. In contrast, treatments T1 (river water) and T3 (negative control) exhibited similar mitotic phase ratios, indicating that the river water did not produce significant cytotoxic alterations in mitotic phase progression. Furthermore, the Pamplonita River water induced a considerable genotoxic effect: the chromosomal abnormality index (CI) increased significantly compared to the negative control, with the genotoxic damage in the river samples (T1) comparable to that induced by the positive control (T2, EMS). Furthermore, a significant inhibition of root growth was observed, with a reduction of approximately 43%, indicating significant biological stress on A. cepa cells. The physicochemical evaluation corroborated the presence of contamination, with levels of turbidity, color, COD, and BOD5 significantly exceeding the limits permitted by national regulations, with Zone 1 (Terminal) being the most affected. This translates into a potential risk to aquatic life and compromises water quality for its various uses.