Carcinogenicity study of sodium hypochlorite in F344 rats

The carcinogenic potential of sodium hypochlorite was examined in F344 rats. Groups of 50 males or 50 females were given sodium hypochlorite in their drinking-water, at concentrations of 0.1 and 0.05% for males and 0.2 and 0.1% for females, for 104 wk. Similar numbers of male and female rats received distilled water without supplement throughout the experiment. All surviving rats were killed at wk 112 (after 8 wk on untreated tap-water). Rats of both sexes given the chemical showed a reduction in body-weight gain, but haematological and biochemical examination of the blood showed no changes due to treatment, and no significant lesions attributable to the treatment were detected in any tissue in the histopathological investigation. Although a variety of tumours developed in all groups, no dose-related change in either the incidence or latent period of tumours was observed for any organ or tissue in either sex. Under the experimental conditions described, therefore, sodium hypochlorite was not carcinogenic in F344 rats.