Evaluation of Tobacco Industrial Wastewater for Genotoxic Characteristics on Allium cepa L. Root Cell Mitosis

Abstract

Due to increased environmental and toxicological problems originating from the release of toxic contaminants in the environment, it has become obvious that cheaper and reliable methods of evaluating genotoxicity of these contaminants are needed. Hence, the effect of industrial effluent from tobacco on Allium cepa L. root mitosis was investigated with the view to ascertaining its genotoxic effects using the biological test. Healthy sprouted onion roots were treated with concentrations of 20%, 50% and 100% of Tobacco wastewater for 6 h, 12 h and 18 h time duration respectively, while distilled water served as control. Healthy roots were harvested after the treatment periods and fixed in 1:3 acetic alcohol for 24h. After this, roots were hydrolysed in 1N HCl before squashing, staining with FLP-Orcein and observed on the microscope. There was significant difference in the mitotic indices between the treatment concentrations (27.71; 32.32; 27.09; 33.85) and (21.98; 26.89; 16.17; 34.04), and the control (20% 50%; 100%; control), at 6 h and 12 h respectively. However, exposures of root cells to even the least concentration beyond 12 h to 18 h produced a toxic effect on the cells and a complete inhibition of mitosis of the root cells. Similarly, the treatment concentrations induced various mitotic chromosomal aberrations such as Stickiness, C-metaphase, bridges, unequal distribution of chromosomes, breaks, laggards, vagrant and ring chromosomes at concentrations of 20%, 50% and 100%, and between 6 and 12 h exposure. These observations confirm the assumption that wastewater of tobacco has a genotoxic potential and capable of affecting DNA biosynthesis, especially when high concentrations are absorbed for a prolonged period of time.