GENOTOXICITY OF OIL-FIELD WASTE-WATER IN NIGERIA

The general toxicity (root growth inhibition and malformation) and gen otoxicity (induction of chromosome aberrations in root cells) of an oi l field wastewater have been investigated by the Allium test. A series of 10 small bulbs of Allium cepa L. were cultivated in various concen trations of the wastewater, and after 48 h one root tip from each bulb was harvested and processed for cytological studies by the aceto-orce in squash technique. After 96 h, mean lengths of root bundles were obt ained and the Effect Concentration (EC) values calculated. Treatment w ith wastewater resulted in significant dose-dependent root growth inhi bition. EC50 (96 h) was 28.5 % while a total phytotoxic effect was ind uced by the undiluted sample. The wastewater is mitodepressive and inc reased significantly the frequency of chromosome aberrations in root c ells (sticky chromosomes, c-mitosis, spindle multipolarity, bridges an d fragments). At lower concentrations c-mitosis was the most common ab erration. 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.