Objective To elucidate that arsenic induces oxidative DNA damage.Methods The genotoxicity of arsenic in human cells was comparatively studied with single cell gel electrophoresis (SCGE) assay in combination with observation of the protective effects of dimethyl sulfoxide (DMSO) and catalase.Results Arsenic, at the concentration of 2.4 μmol by coincubation for 24 hours, significantly induced DNA damage in HL60, a human promyelocytic leukemia cell line. In contrast, significant DNA damage was found in human lymphocytes at the concentration of 4.8 μM or above. DMSO and catalase significantly reduced the arsenic-induced DNA strand breaks in both HL60 and lymphocytes.Conclusions Our data indicate that arsenic, within micromolar concentrations, induces typical and various extent of DNA damage in human cells via reactive oxygen species, chiefly hydrogen peroxide (H 2O 2) and superoxide (O 2 -), in a dose-dependent manner.

Objective To study the different responses of cells to arsenic-induced genotoxicity and its possible mechanisms.Methods Single cell gel electrophoresis (SCGE) assay was used to study the arsenic-induced DNA damage in human promyelocytic HL60,DMSO-differentiated HL60 (DMSO-HL60)，PMA-differentiated HL60 (PMA-HL60) and unstimulated human lymphocytes.Results Significant dose-effect relationship and time-course were found between arsenic exposure and DNA damage in the treated cells.The sequence for the sensitivity of cells to arsenic-induced genotoxicity was obtained as follows.PMA-HL60 > DMSO-HL60 > HL60 > human lymphocytes.A same result was obtained by counting the classes of the comet tail and by measuring the tail moment in human lymphocytes.The same significance was achieved using nonparametric Mann-Whitney multiple comparisons for visual classes of comet tail and parametric Tukey multiple comparisons for Tail moment.A higher correlation was shown between the comet tail of Class 5,than between total positive comet tail,and doses of arsenic.Conclusions Micromolar amount of arsenic induces DNA damage in human cells.Different populations of cells had different responses to arsenic-induced genotoxicity.SCGE assay is a economic,rapid,sensitive and economic method detecting genotoxicity.It could be applied in all levels of monitoring and study on environmental pollution and human diseases (arsenic pollution).