Chlorine may purify drinking water, but what does it leave behind?

water pours into glass

Image: Health Science Center

Three faculty-researchers at the School of Public Health have published a study that looks at how chlorine can react to organic matter in drinking water to create substances known as disinfection byproducts, or DBPs, which pose serious health risks in high concentrations.

Around the world, chlorine is a staple of public health efforts to disinfect drinking water. This purification process has made water-borne diseases such as cholera largely a memory in the developed world, but chlorinating drinking water is not without risk.

The research, published in the Chemical Engineering Journal, looked at a wide range of existing research into DBPs, focusing on the roles that chemicals like iodide and bromide, metal ions, metal oxides and nanoparticles play in DBP formation. The authors are Professor Virender Sharma, Professor Thomas McDonald and Assistant Professor Leslie Cizmas, all in the Environmental and Occupational Health Department

“Bromide and iodide are chemicals found in water that form brominated and iodinated DBPs when water is disinfected with chlorine,” Sharma said. “Many of these compounds have a higher toxicity than chlorinated DBPs, making them an important topic of study. In addition, the rate at which DBPs form can be affected by water conditions and the presence of other substances like metals and nanoparticles.”

The results of this study provide a starting point for further research into DBP formation, particularly as influenced by metal ions, metal oxides and nanoparticles. Research findings highlight the need for further systematic studies, especially related to the increased use of nanoparticles, and the need for more information on how factors ranging from pH to light exposure play a role in DBP formation.

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