The fluoride added to water gets it up to 0.7mg/liter.

That ends up to be 2 or 3 drops in a 55 gallon drums worth of water. Not much.

Fluoride is a natural substance and is found in many areas drinking water already. Many areas in much higher concentrations than 0.7mg/liter, so realistically people all over the world have drank fluoridated water for thousands of years.

You have to well over double the 0.7 before any health issues may appear and the first to appear is at about triple the concentration in kids under 8 years old who drink it for years getting spots on their teeth. The spots are only superficial.

Going into concentrations even higher than that CAN cause health issues when drank for longer periods of time. All of those cases being from naturally occurring fluoride, which actually effects somewhere north of 20% of the world's population.

Which makes the argument that fluoride in our water keeps us passive as being extra stupid, since water sourced around Columbia (the country) is far higher than .07mg/liter and Columbia seems to be caught in violence and turmoil and instability quite a bit over the decades.

*edit: Colombia