Sodium chlorate induces DNA damage and DNA-protein cross-linking in rat intestine: A dose dependent study

Sodium chlorate (NaClO₃) is widely used in paper and pulp industries and as a non-selective herbicide. It is also a major by-product generated upon disinfection of drinking water by chlorine dioxide. In this study, we have investigated the genotoxicity of NaClO₃ on the small intestine of rats. Adult male rats were divided into 5 groups: one control and four NaClO₃ treated groups. The NaClO₃ treated groups were given a single acute oral dose of NaClO₃ (100, 250, 500 and 750 mg/kg body weight) and sacrificed 24 h later. Administration of NaClO₃ caused significant DNA damage in a dose dependent manner in the rat intestine. This was evident from the comet assay which showed DNA strand breaks and was further confirmed by agarose gel electrophoresis and release of free nucleotides. Increased DNA protein cross-linking in NaClO₃ administered groups showed formation of a critical lesion which hampers activities of proteins/enzymes involved in DNA repair, transcription and replication. Thus, oral administration of NaClO₃ induces DNA damage in the rat intestine, probably through chlorate induced production of reactive oxygen species.