DNA damage evaluated by alkaline single cell gel electrophoresis (SCGE) in children of Chernobyl, 10 years after the disaster

Using the alkaline single cell gel electrophoresis (Comet) assay, the extent of DNA damage was evaluated in leukocytes of 43 Belarussian children (16 healthy and 27 affected by thyroid cancer). Thirty-nine healthy children from Pisa (Italy) were enrolled in the study as controls. In addition to basal levels of DNA damage, leukocytes were treated in vitro with bleomycin (BLM), a radiomimetic drug, to evaluate a possible adaptive response in different groups of children. Results with the Comet assay indicated an increased level of DNA damage (P = 0.037) in leukocytes of Belarussian children compared to the Italian control group. In addition, within the Belarus group, lower basal levels of DNA damage (P < 0.001) were found in children with cancer compared to healthy children. Tumor affected children were living in less radiocontaminated areas (P < 0.04) than the healthy children and there was a significant relationship (P = 0.03) between the amount of environmental radiocontamination and DNA damage in leukocytes. There were no differences in the sensitivity of leukocytes from different groups of children to BLM, indicating the absence of an adaptive response. The lack of an adaptive response may have been due to the use of noncycling cells and/or the bleomycin dose chosen. Tests for the presence of clastogenic factors (CF) in the blood serum of children showed that 39% of the tumor affected children and 19% of the healthy children in the exposed group were positive as compared to the Italian control group (0%) (Chi-square test, P < 0.04). The higher levels of genomic damage in children evaluated 10 years after the Chernobyl disaster could be related to the increased incidence of individuals with CE (C) 2001 Elsevier Science B.V. All rights reserved.