Chlorine dioxide and hemodialysis.

In the United States chlorination of potable water supplies has been the standard method of disinfection for about 75 years. In recent times concern has been raised about the propensity of chlorination to introduce potentially carcinogenic trihalomethanes (THM) such as chloroform into finished water. The levels of THM introduced depend on many factors including the quality of the raw water. Numerous community water treatment facilities are experiencing difficulty in meeting current U.S. Environmental Protection Agency standards, and it is likely that the permissible levels may be lowered in the future. An alternative to chlorination which does not generate THM during disinfection is chlorine dioxide, but there are concerns about the acute and chronic toxicity of ClO2 and its disinfection by-products, chlorite and chlorate. Deleterious effects of moderately high levels of these oxychlorines have been demonstrated experimentally on red blood cells, thyroid function, and development in laboratory animals. Adverse effects in controlled prospective studies in humans and in actual use situations in community water supplies have as yet failed to reveal clear evidence of adverse health effects. Among groups who may be at special risk from this suggested alternative are patients who must undergo chronic extracorporeal hemodialysis. The special needs, precautions, and experience to date in regard to finished water are reviewed. Again, very limited human experience has failed to reveal adverse health effects. Further study, caution, and extreme vigilance are indicated, but dialysis patients in carefully controlled facilities may be at no greater risk than the general population.