What controversial compound is added to drinking water in many cities?

A: Fluoride

In 1945, the US government began adding fluoride to public water sources in an attempt to help prevent tooth decay. By 2008, 72% of US cities added fluoride to their water. The Center for Disease Control continues to approve the practice, despite a Harvard study linking water fluoridation to long term brain damage resulting in loss of IQ , similar to lead and mercury.

Prolonged exposure to water fluoridation was also seen to cause skin irritation, thyroid dysfunction, and an increased incidence of cancer in rats. Human studies have also found a link between water fluoridation and osteosarcoma (bone cancer) and lung cancer. If you don’t have a water purifier for your tap water, it might be a good idea to consider purchasing one.