Genotoxic Hazard and Oxidative Stress Induced by Wastewater Irrigated Soil With Special Reference to Pesticides and Heavy Metal Pollution

Abstract

Enhancement of industrial growth and urbanization, soil contamination is increasingly prominent. Therefore, it’s important to examine possible adverse effects of industrial waste. Samples were found to be polluted with several heavy-metals and pesticides. Gas chromatographic results showed occurrence of high-level of organochlorine and organophosphate pesticides. Genotoxicity of soil extracts was assessed using environmental-risk assessment models. Soil samples were extracted in hexane and dichloromethane solvents and were evaluated for genotoxic potential by prokaryotic (Ames test, plasmid nicking assay and E. coli K-12 DNA repair defective mutants) and eukaryotic (Allium cepa root chromosomal aberration and Vigna radiata seed-germination test) bioassays. Strain TA98 was found most susceptible among soil extracts. Hexane soil extract of wastewater irrigation was determined more mutagenic than DCM samples in terms of mutagenic index, mutagenic potential and induction factor for Ames strains. The damage in DNA repair defective mutants of hexane extracts were found higher compared to DCM extracts at dose of 20 μl/ml of culture. Survival in polA, lexA and recA mutants were 39%, 47% and 55% while treated with hexane extract. Allium cepa test, mitotic index was decreased in dose-dependent way and various kinds of chromosomal aberrations were found. Vigna radiata seeds germination and other parameters were also affected when treated with contaminated soil. Oxidative stress in V. radiata roots were also showed under CLS microscope. Genotoxicity of contaminated soil extract was also confirmed by plasmid nicking test. Our study provides possible explanation for the assessment of potential health and environmental hazards of the industrial region.