Risk evaluation of industrial wastewater on plants using onion(Allium cepa l) chromosome aberration assay

Abstract

Rapid strides in industrialization coupled with incomplete sewage treatment system have led to indiscriminate discharge of potentially mutagenic wastewater into agricultural lands and water bodies. The response of Onion plant genetic material to the presence of potential cytotoxic and genotoxic substances in the environment was used to evaluate the toxicity of chemical effluent collected from a chemical industry in Enugu, Nigeria. The Allium test procedure was used. The concentrations of heavy metals (Cu, Co, Cd, Pb) were also determined. The data obtained showed that the mitotic index (MI) decreased as effluent concentration and treatment durations increased. Significant differences in MI at different concentrations and treatment durations were observed. Conversely, percentage of abnormal dividing cells significantly (P<0.05) increased as the concentration and treatment durations increased. Diverse chromosomal aberrations and cytotoxic problems were observed. These ranged from a mild C-mitotic effect at lower concentrations to vacuolated nucleues and even cytokinetic failure at higher concentrations. The adverse effects of this untreated wastewater on the ecosystem of which one of the most vulnerable are plants are discussed.