A Answers (2)
There are few reported risks associated with fluoride use when taken in normal daily recommended amounts. However, fluoride taken in large doses over extended periods of time can cause discoloration in the teeth in young children, a condition known as enamel fluorosis, or cause bone problems. In older adults, taking excessive amounts of fluoride may worsen joint pain, kidney problems, and stomach ulcers.
American Dental Association answered
For more than 65 years community fluoridated water has been shown to be safe and effective. It prevents tooth decay. Despite the many myths, all studies show that it does not cause any health issues. The only possibility is very mild or mild fluorosis, which are light yellow lines on the teeth which are typically not noticeable from the distance you speak to someone.