Molecular Evaluation and Cytogenetic Effect of Spent Engine Oil in Lagos, Nigeria Using Allium cepa Assay and RAPD-PCR Technique

In nations developing industrially, spent engine oil (SEO) has become a major source of pollution. Improper disposal of these chemicals portends danger to the flora and fauna in the environment. Evaluation of the molecular and cytogenetic effect of SEO was done using Allium cepa assay. Different concentrations of 0.5%, 1%, 5%, 10%, 25% & 50% of SEO were used for the toxicity assay and root growth inhibition as well as to obtain the EC₅₀ at 4%. Public tap water was used as the test control. Hereafter, 10%, 25%, 50% & 100% of the EC₅₀ were used for the genotoxicity assay. Genotoxicity was also examined using RAPD-PCR analysis. Cytogenetic studies showed a decrease in mitotic index as test concentration increased. The percentage aberration; fragments, laggards, bridges, vagrants, micronuclei and binuclei increased as the test concentration increased and as mitotic index reduced. Toxicity test for the Allium cepashowed wilting roots and discoloration of roots at 3-7days. Mean root length also showed a reduction compared to percentage control at a significant difference of (p<0.05). Dendograms were generated from the bands produced by the RAPD primer using sequential hierarchical and nested (SAHN) clustering option of the NTSYS-pc 2.02j software package. A total no of 101 bands were scored from five primers with the highest no of bands scored from OPB 08 primer (33 bands), and the lowest no of bands of 4 scored from the OPB 06. Data analysis for the five 10bp operon primers showed Individuals from the 10%, 25% and 50% test concentrations clustering together while separate clustering was observed for the 100% test concentration individuals at a similarity coefficient of 20%. The disposal of spent engine oil within neighbourhoods and residential areas is hazardous and a known source of environmental pollution. Stricter measures need to be put in place to regulate activities that release SEO into the environment.

Keywords: Spent Engine Oil, Allium cepa, RAPD-PCR, EC₅₀