Abstract: ObjectiveTo the mechanism of skin pathologic change caused by arsenism resulting from coal-buring.Methods The expressions of malondialdelyde(MDA)and 4-HNE in the skins were analysed by EnVision TM +System immuno-histochemistry methods.The activity of superoxide dismutase(SOD),glutathione peroxidase(GSH-Px)and the content of malondialdelyde(MDA)in blood of patients were measured and analysed.ResultsThe positive cell density and the positive percentages of MDA and 4-HNE gradually strengthened along with the patient's skin pathological changes worsened.The above mentioned bio-markers in hyperkeratosis group(B group),pre-carcinoma group(C group)and carinoma group(D group)were all over the normal group or general pathological changes group(A group)(P<0.05,P<0.01),and among the every pathological changes groups existing significance to varying degrees(P<0.05,P<0.01).Compared with the control,the SOD and GSH-Px activity were lower(P<0.05),while the MDA content were higher(P<0.05)in endemic subjects.ConclusionsIt suggested that the immuno-histochemistry assay of MDA and 4-HNE can be used as a sensitive and specialized method to reflect oxidative damage, and may help early finding and monitoring of arseniasis.