Chlorine Added to most municipal water supplies, this disinfectant hardens arteries, destroys proteins in the body, irritates skin and sinus conditions, and aggravates asthma, allergies, and respiratory problems. Chloroform This powerful by-product of chlorination causes excessive free radical formation (accelerated aging), normal cells to mutate, and cholesterol to oxidize. It's a known carcinogen! DCA (dichloro acetic acid) This chlorine byproduct alters cholesterol metabolism and has been shown to cause liver cancer in lab animals. MX (another chlorinated acid) Another byproduct of chlorination, MX is known to cause genetic mutations that can lead to cancer growth and has been found in all chlorinated water for which it was tested. Cancer Research has indicated that drinking chlorinated water may increase the risks for bladder and rectal cancer in the United States.