The physiological impact of chronic 12 week ingestion of chlorine dioxide and its byproducts, chlorite and chlorate, was compared to the effects of chlorine, chloramine and untreated water. The water disinfectant solutions were administered daily (500 ml, 5 ppm) to normal healthy adult male volunteers. An extensive battery of tests was used to evaluate the physiological impact of the ingested water disinfectants. Upon analysis of both quantitative and qualitative parameters it was concluded that the 12 week chronic administration of chlorine dioxide and its byproducts was accompanied by no clinically important physiological effects.