Cytotoxic Effects and Genotoxic Screening of Pharmaceutical Effluents using Onion Bulbs (Allium cepa L.)

Background: Pharmaceutical effluents like other pharmaceutical effluents are toxic waste water generated from drug industries which when discharged directly into the environment without proper handling and treatments may cause deleterious effects on human health and environment.

Aim: This research is aimed at investigating the potential cytotoxic and genotoxic effect of effluents released by three different pharmaceutical industries in Sango Industrial Area of Ogun State in Nigeria using the USEPA recommended Allium cepa test.

Methodology: Each of the effluents were prepared into different concentrations using distilled water (1%, 2%, 3%, 4%, 5%, 10%, 25%, 50% and 100% respectively) and their cytotoxicity on the root length of a series of onion bulbs was observed after three days of exposure. Cytological studies on the root tips of onion bulbs using five concentrations of each effluent were also examined by Aceto-orcein squash technique. Mitotic index which is the ratio of the number of cells dividing to number of cells counted was observed to decrease with increasing concentration of all the effluents compared to the control. Chromosome aberrations induced at different concentrations were observed under microscopes.

Result: Significant results were observed in the Root length Evaluation and Chromosomal Aberration Evaluation tests respectively after three days. Effluent C seems to be the most toxic on the root length of the onion bulbs as it reduced from 1.2cm to as low as 0.30cm, followed by effluent B and A with 0.60cm and 0.70cm respectively. But Effluent A has the most % of aberrant cells with 5.32% and Effluent C with 3.03%. Most of the aberrations induced were vagrants, bridges and sticky chromosomes.

Discussion and Conclusion: The results from this study showed that effluents from these pharmaceutical industries have toxic chemicals and that Allium cepa test in relation to this study has proved to be an effective tool that may be employed by environmental toxicologists in monitoring industrial effluents before they are discharged into the environment.