http://en.wikipedia.org/wiki/Water_fluoridation_controversy
My husband is adamantly against fluoride, it has shown to be poison in high doses, although it's extremely unlikely - it does exist. They point to fluoride helping teeth, but it's such a small help. My husband and I were both raised in a city that adds it to the water, and both of us are scheduled to have dentures this year - he's 32, i'm 29. Genetics and cleanliness and dentist visits have WAYYY more to do with fluoride. While it's true about the controversy - see the website, google "fluoride in water" - the truth is, I'd spend the time worrying about my kids brushing right and flossing. MY son is going to have all his teeth in 30 years, and I don't honestly think fluoride makes a huge difference. Probably better to avoid it, it hasn't proven to help that much, but like someone said - a little hasn't been proven to hurt at all. It's just a question of do you want to put something more in your body that may NOT help enough to cancel the risks? It's up to you in the end...