The evaluation of genotoxic potential of water bodies in and around Metro Manila using the Allium cepa (onion) assay

Screening for hazardous chemicals and potential mutagens in water bodies, which are often the recipients of contaminated and polluted substances, is being accepted as a routine method in environmental monitoring programs. In this study, Allium cepa method was used to evaluate the genotoxic potential of various water bodies namely- Pasig and Marikina river and the Estero de Vitas located in and around Metro Manila, Philippines. Morphological modifications of the Allium cepa roots, inhibition of root growth, mitotic index and the induction of high frequency of chromosomal aberrations comprising of chromosome fragments, laggards, anaphase and telophase bridges and C-mitotic effect were observed in the Allium cepa roots exposed to water samples from three sources tested as compared to the control. The observed biological effects of the water samples appeared to be related to the physicochemical characteristics studied using Atomic Absorption Spectroscopy. The results of the investigation demonstrate that the hazardous substances and pollutants present in the water bodies has genotoxic and cytotoxic effects on Allium cepa cells and there could be a potential threat to the human health as well as to the water ecosystems in and around Metro Manila. Hence the Allium cepa test could be used to obtain preliminary information about the presence of genotoxic and or cytotoxic substances from the water bodies while performing the environmental monitoring