Toxicity Evaluation and Cytogenetic Screening of Process Water Using a Plant Bioassay

Abstract

ABSTRACT:The effect of toxic substances on aquatic lives from a wastewater indiscriminately discharged into the environment during oil and gas exploration activities in Nigeria is the focus of this study. A plant bioassay, the Allium cepa test, was used for the cytogenotoxicity screening of process water on root growth inhibition and chromosome abnormalities in the meristematic roots of the plant. Results of the physicochemical analysis of the wastewater collected from Nigerian Agip Oil Company (NAOC) facility at Ogboinbiri in Bayelsa State at the point of discharge into the environment showed that it had an unpleasant odour, was slightly alkaline (pH 7.72) and had high electrical conductivity (2793.33 µS/cm). Lead, manganese, iron, chromium and nickel were present at amounts (0.13, 0.33, 4.47, 0.17 and 0.10 mg/l respectively) above national (NESREA) and international (USEPA) limits for effluent discharge. Macroscopic evaluation of A. cepa cultivated in the wastewater resulted in significant (p<0.05) concentration-dependent root growth inhibition with an EC 50 value of 14.8 % at 96 h. Root tip cells of the onion bulbs processed for cytological studies by the aceto-orcein squash technique after exposure to the wastewater for 48 h at concentrations of 0.5, 1.0, 2. 5, 5.0, and 10% (v/v; wastewater/tap water) showed chromosomal aberrations at all concentrations. Statistical analysis of microscopic results show significant (p<0.05) concentration-dependent frequency of aberrant chromosomes and reduction of mitotic index. The findings in this study calls for proper treatment of process water before its discharge into water bodies to avoid cyto-genetic damages to aquatic lives.

Genotoxic Activities of Polysaccharides from Cotyledon and Coat of Fermented and Unfermented Annona squamosa L. Seed

“…The Allium cepa test is an important test, where the roots grow in direct contact with the substances of interest enabling possible damage to the DNA of humans to be predicted. The Allium cepa assay involved measurements of the length of the root and chromosome damage and proved to be a suitable model system for the measurement of environmental cytogenotoxic potential of pollutants (Olorunfemi et al, 2015). Rubeena and Thoppil, (2020) also reported that analysis of metaphase chromosomes is an important and most widely used method to assess the mutagenic potential of a given agent.…”

Bioassays based on higher plants as excellent dosimeters for ecotoxicity monitoring: A review

“…For this purpose, following four microscopic genetic endpoints are reported for the assessment of toxicity in A. cepa, namely, mitotic index (MI), chromosonal aberrations (CA), nuclear aberrations (NA) and micronuclei (MN) (Leme and Marin-Morales, 2009). Additionally, some researchers have also used macroscopic characteristics such as number of root, length of root and root physical appearance for the indication of toxicity (Bianchi et al, 2011;Fazili and Ahmad, 2014;Lerda et al, 2010;Olorunfemi et al, 2011b;Olorunfemi et al, 2015b;Radić et al, 2010;Roa et al, 2012;Siddiqui et al, 2011;TORRES et al, 2014). These end points are used for the evaluation of cytotoxicity, genotoxicity and mutagenicity of the pollutant.…”

Genotoxicity assessment of three industrial effluents using the Allium cepa bioassay

“…Odeigah et al (1997) reported the genotoxicity of oil field wastewater; El-Shaby et al (2003) reported the genotoxicity of industrial wastewater from the Sandub area in Mansoura district in Egypt, while Babatunde and Bakare (2006) reported the toxicity of wastewaters from Agbara Industrial Estate, Nigeria. Olorunfemi et al (2015) had also reported the toxicity of process water from Nigeria Agip Oil Company (NAOC) and Kannangara and Pathiratne (2015) reported the genotoxicity of textile dyeing effluent and leachate from a tannery effluent. Hemachandra and Pathiratne (2017) also observed that raw water induced statistically significant root growth retardation, mitodepression and chromosomal abnormalities in the root system of plants.…”