A recent study by Drs. Georg Wondrak and Frank Duca explored the effects of drinking chlorinated water on mouse gut microbiota. Their findings revealed a decline in fecal microbiota diversity and notable shifts in fecal bacterial composition. With potential public health implications for humans, these results underscore the need for further research in human subjects.

What were their key findings?

This study examined the effects of drinking water chlorination on gut microbiota composition, revealing the potential public health risks posed by exposure to chemical disinfectants in drinking water. Researchers compared fecal microbiota samples from mice drinking chlorinated water to mice drinking unchlorinated water. Results showed significant changes in the bacterial composition of the fecal samples as a result of exposure to chlorinated drinking water. As one of the first studies to examine the effects of drinking chlorinated water on gut health and microbiota, these findings illustrate the need for additional research regarding human health and large population impacts. 

Why do we chlorinate drinking water?

Drinking water can be contaminated by bacteria, viruses, and other microorganisms that, when ingested, can cause gastrointestinal illnesses. Public water systems address this issue by treating water with chlorine, a process known as chlorination. Chlorination disinfects water so it is safe to drink when it reaches a household tap. By killing these harmful microorganisms, chlorination helps prevent illnesses like diarrhea, vomiting, and cramps. 

What chemicals do public water treatment systems use?

Chlorination agents are chemicals used in treatment facilities to treat and disinfect water so it is hygienic for household use. Most facilities use chlorine and chloramines to disinfect water, but other disinfectants like chlorine dioxide may be used as well. 

What chemicals were tested in this study?

Researchers tested and compared the effects of drinking water treated with inorganic hypochlorous acid (HOCl) and chloramine (TCIC) to untreated drinking water. Chlorination levels adhered to EPA-defined Maximum Residual Disinfection Levels, meaning the chemicals were present in similar concentrations to normal levels found in household tap water. 

What does this mean for public health? 

The gastrointestinal microbiota is an important factor in human health, making it an important target for public health initiatives. Exposure to excessive chlorination agents can sometimes lead to the development of chronic inflammatory respiratory diseases and gastrointestinal issues. Clean drinking water is a widespread public health issue, so it is essential to evaluate current drinking water treatment systems to ensure public safety.

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