Toxicity evaluation of waste effluent from cassava-processing factory in lagos state, nigeria using the Allium cepa assay
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Date
2018
Journal Title
Journal ISSN
Volume Title
Publisher
Faculty of Science, Obafemi Awolowo University
Abstract
Mutagenic and genotoxic effects of cassava wastewater (CWW) were investigated by assay of Allium cepa root
meristematic cells. The physicochemical parameters of the wastewater samples showing cyanide content were
also determined. In Allium root growth inhibition test, experimental onion bulbs were cultivated in various
concentrations of the CWW and distilled water was used as a negative control. After 72 h, the root tips from the
treated bulb were processed for cytological studies by orcein squash technique. The mean lengths of root
bundles were obtained and effective concentration (EC) values calculated. The cytotoxic effects on the onion
root tips showed strong growth retardation at high concentrations of the effluent with EC value of 10%. The 50
mitotic index (MI) rapidly decreased with increasing effluent concentration compared to control. There was
significant increase in frequency of chromosome aberrations (sticky chromosome, c-mitosis, vagrant
chromosome, bridges fragment, binucleated cells, multipolar anaphase, attached chromosome and laggard
chromosome) in root tip meristem cells of Allium cepa at all tested concentrations. Further analysis using oneway ANOVA revealed that there was a statistically significant difference (p<0.05) in concentration-dependent
inhibition of onion root growth, mitotic index and induction of chromosomal aberration in the Allium cepa test.
The results indicate that the effluent samples collected were highly mutagenic. The results of physicochemical
analysis revealed that the concentrations of some parameters (conductivity, total suspended solid (TSS), total
dissolved solid (TDS), biological oxygen demand (BOD), nitrate, cyanide, chloride and metals-magnesium,
aluminum, chromium, cadmium, manganese and iron) were above the maximum permissible limit set by world
health organization (WHO) and could partly be correlated with the toxicity of wastewater. The findings indicate
that the substances contained in the cassava effluents may be toxic to living organisms and may pollute the
environment if untreated.
Description
Keywords
Mutagenicity, Genotoxicity, Cassava wastewater, Chromosomal Aberration, Mitotic Index, Cyanide, Allium cepa
Citation
Ogunyemi, A. K., Samuel, T. A., Amund, O. O., & Ilori, M. O. (2017). Toxicity evaluation of waste effluent from cassava-processing factory in Lagos state, Nigeria using the Allium cepa assay. Ife Journal of Science, 19(2), 369-377.