Deoxyribonucleic acid damage in Iranian veterans 25 years after wartime exposure to sulfur mustard

Background: More than 100,000 Iranian veterans and civilians still suffer from various long‑term complications due to their exposure to sulfur mustard (SM) during the Iran-Iraq war in 1983-88. The aim of the study was to investigate DNA damage of SM in veterans who were exposed to SM, 23-27 years prior to this study. Materials and Methods: Blood samples were obtained from the veterans and healthy volunteers as negative controls. Lymphocytes were isolated from blood samples and DNA breaks were measured using single‑cell microgel electrophoresis technique under alkaline conditions (comet assay). Single cells were analyzed with “Tri Tek Comet Score version 1.5” software and DNA break was measured based on the percentage of tail DNA alone, or in the presence of H2O2 (25 μM) as a positive control. Results: A total of 25 SM exposed male veterans and 25 male healthy volunteers with similar ages (44.66 ± 6.2 and 42.12 ± 5.75 years, respectively) were studied. Percentage of the lymphocyte DNA damage was significantly (P 0.01) higher in the SM‑exposed individuals than in the controls (6.47 ± 0.52 and 1.31 ± 0.35, respectively). Percentages of DNA damage in the different age groups of 35-39, 40-44, 45-49, and 50-54 years in SM‑exposed veterans (5.48 ± 0.17, 6.7 3 ± 1.58, 6.42 ± 0.22, and 7.27 ± 0.38, respectively) were all significantly (P 0.05) higher than the controls (1.18 ± 0.25, 1.53 ± 0.22, 1.27 ± 0.20, and 1.42 ± 0.10, respectively). The lymphocytes incubated with H2O2 had much higher DNA damage as expected. The average of tail DNA is 42.12 ± 2.75% for control cells + H2O2 and 18.48 ± 2.14% for patients cells + H2O2; P 0.001. Conclusion: SM exposure of the veterans revealed DNA damage as judged by the comet assay.