Subchronic Toxicity of Sodium Chlorite in the Rat

Chlorine dioxide (ClO2) is currently used in many countries as a drinking water disinfectant. The chlorite ion (ClO2-) is the primary degradation product of ClO2 when it is used to treat drinking water. In this study, sodium chlorite was administered daily by gavage to rats for 13 weeks at dose levels of 0, 10, 25, or 80 mg/kg/day. At the conclusion of the study, all surviving animals were killed and subjected to a gross necropsy. Hematology, blood chemistry evaluations and urinalysis were performed. At 80 mg/kg/day, there were several treatment-related deaths and morphological changes in erythrocytes were observed. Mean erythrocyte count was decreased in both sexes. In males, hematocrit and hemoglobin levels were decreased and methemoglobin levels were increased. Splenic extramedullary hemopoiesis was observed in some animals at 80 mg/kg/day. At 25 mg/kg/day, methemoglobin was increased in males. No adverse toxicological effects were noted at 10 mg/kg/day.