Genotoxicity of oil field wastewater in Nigeria

Abstract

The general toxicity (root growth inhibition and malformation) and genotoxicity (induction of chromosome aberrations in root cells) of an oil field wastewater have been investigated by the Allium test. A series of 10 small bulbs of Allium cepa L. were cultivated in various concentrations of the wastewater, and after 48h one root tip from each bulb was harvested and processed for cytological studies by the aceto-orcein squash technique. After 96 h, mean lengths of root bundles were obtain and the Effect Concentration (EC) values calculated. Treatment with wastewater resulted in significant dose-dependent root growth inhibition. EC50 (96h) was 28.5% while a total phytotoxic effect was induced by the undiluted sample. The wastewater is mitodepressive and increase significantly the frequency of chromosome aberrations in root cells (sticky chromosomes, c-mitosis, spindle multipolarity, bridges and fragments). At lower concentrations c-mitosis was the most common aberration. The suitability of the Allium test in genotoxicity screening is highlighted and the impact and significance of positive results on the environment and human health are discussed.