Biochemical effects and genotoxic evaluation of Warri Refinery and Petrochemical Company (WRPC) wastewater

Abstract

Wastewater samples from Warri Refinery and Petrochemical Company (WRPC) were collected from the discharge point and 500m away from the point of discharge and analysed for physicochemical parameters using standard methods. Serially prepared effluent concentrations were subjected to aceto-orcein squash chromosome aberration Allium cepa assay for genotoxic evaluations. Superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) enzyme
activities were assessed on root-tips of A. cepa L. exposed to the wastewater samples. Physicochemical analysis showed that levels of lead, chromium, zinc, manganese, cadmium, iron and copper exceeded SON permissible limits and were higher at the discharge point than downstream. There was a rapid decrease in mitotic index and statistically significant (p<0.05) increase in chromosome aberrations in the root tip cells with increasing effluent concentration. SOD, CAT and GSH-Px enzyme activities decreased in the common onion root tip cells indicating high rate of genotoxicity. The findings reveal that the toxic chemicals in the wastewater are responsible for the observed genotoxic effects by oxidative damage on the onion root tip cells.