Massive application of pesticides had generated a considerable concern in the public. Potentials of chlorpyrifos [O,O-diethyl-O-(3,5,6-trichloro-2- pyridinyl) phosphorothionate] and cypermethrin [(RS)-α-cyano-3- phenoxybenzyl (1RS)-cis-trans-3-(2,2-dichlorovinyl)-2,2- dimethylcyclopropanecarboxylate] to induce the excision-repairable DNA damage, DNA strand breakage, and DNA hypomethylation in ICR mouse hepatocytes were investigated. It was showed that chlorpyrifos and cypermethrin didn't increase the incorporation of 3H-TdR into DNA of ICR mou...