Is Chlorine harmful?

The introduction of chlorine to the public drinking water was introduced in 1908 in Chicago and was used to eliminate many types of waterborne diseases, such as cholera and typhoid fever.  Before chlorination typhoid fever was responsible for the death of 1 in 1000 people in many major cities.  Chlorine has been used to disinfect municipal water for over 80 years and has had some positive effects on public health.  In the 1970s, it was discovered that chlorine, when added to water, forms Trihalomethanes (chlorinated by-products) by combining with certain naturally occurring organic matter, such as vegetation and algae. The American Journal of Public Health published a report in 1992 that showed a 15% to 35% increase in certain types of cancer in people who consume chlorinated water.  The National Cancer Institute estimates the cancer risks for people who consume chlorinated water to be up to 93% higher than for people who drink de-chlorinated water.