Correlations between DNA and cytogenetic damage induced after chemical treatment and radiation

The induction of damage in human lymphocytes has been compared after treatment in vitro with two different agents, the chemical o-phenylenediamine (o-PDA) and gamma irradiation, in the alkaline single cell gel electrophoresis (Comet) assay, and after cytogenetic analysis. The chemical treatment caused dose-related increases in DNA damage in the Comet assay and cytogenetic damage in the first and second metaphases. The results revealed a very strong association between the two types of damage. Correlation coefficients were from 0.95 to 0.97. From previous studies, high correlation coefficients of 0.99 and 0.97 in the same assays were also evaluated for X-rays and fast neutrons, respectively. On the basis of such results, we suggest that the Comet assay responses provide a good prediction of cytogenetic damage. Thus, because of its simplicity and rapidity, the Comet assay would appear to be a very useful tool for determining the genotoxicity of environmental agents.