The unscheduled DNA synthesis(UDS) and the inhibition of whole mouse DNA synthesis test(DSI). Were used to detect the mutagenicity of water organic extract substances(WOES) from Nan-Si Lake.The main index that differentiates the damage of DNA matter was inhibition of mouse testicular DNA synthesis. The results show that IVOES from Nan-Si Lake can increase the CPM of lymphocyte apparently; it has significant inhibition for DNA synthesis of liver. Kidney and testis; and there is a significant dose-effect rela...