Genotoxicity in lead treated human lymphocytes evaluated by micronucleus and comet assays

Abstract

Lead (Pb) which plays a significant role in modern industry is related to a broad range of physiological, biochemical, behavioural and genetical dysfunctions. Its exposure leads to an increased frequency of genetic aberrations in humans. Hence, this study was designed to assess the genotoxic effect of lead acetate at three dosage levels (10, 25 and 50 µg/mL) by employing: the Cytokinesis Block Micronucleus (CBMN) assay and the Comet assay in Peripheral Blood Lymphocyte Cultures. The results of this study revealed an increased level of DNA damage among treated groups. A significant increase in the tail length of comets and other indices was observed at 25 and 50 µg/mL concentrations comparatively. Thus, lead acetate induced single-strand breaks (SSB) and double strand breaks (DSB) in DNA, alkali-labile sites (ALS), oxidative DNA damage as well as DNA-DNA/DNA-protein/DNA-metal cross linking as evidenced by the Comet assay. The chromosome breakage, DNA misrepair, chromosome loss and telomere end fusion were determined by the Micronucleus assay. Micronucleus frequency in treated lymphocytes was significantly higher as compared to controls. Nucleoplasmic bridges increased significantly and Nuclear buds increased at higher two doses only in exposed cultures. Thus, these assays are better indices for lead induced genotoxicity and metal-nucleus interactions.