werepossum said:
If I remember this correctly, floride is a class of flourine compound, not a specific substance. (Literally an ionic form of flourine, but being a halogen it's highly reactive so it's never actually floride, but a floride compound. Think clorides or bromides. Halogens are also used in lights.) And some florides can be very deadly. But I think the compounds they add to municipal water are probably milder than the clorine added. I *think* it is absorbed by and strengthens enamel rather than killing or inhibiting bacteria. But I may be remembering that wrong.
As one of the poor fools currently floundering in Organic chemistry, I can tell you that just because something has Fluorine in it, doesn't make it poisonous. For instance, I'm sure many of you cook on TEFLON pans, and all teflon is is polymers of repeating carbon-carbon backbones with two fluorines attached: (CCL2-CCl2-CCl-2) N times. That's not to say you should ever, ever EAT Teflon. Or if your cheap teflon pan starts to bubble and flake off you should keep using it, due to said risk of eating it.
Elements in the pure form have entirely different properties than elements bonded to say, carbon, and then they have completely different properties if they are bonded to water. And then, the organization of molecules gives them different properties.
Then there are things like chirality. Molecules can be left or right handed, and the two versions react differently with your body. For instance, the receptors in your nose that you use to smell things are chiral, so the left handed molecule smells differently than the right handed molecule. Or, your body uses only a specific handedness of glucose if I remember my Biology correctly, and the other glucose makes the tough indigestible outer covering of plants. Or there was a drug I read about released many years ago to prevent morning sickness, which was an even mixture of right and left-handed molecules. One had the desired effects, the other caused rampant birth defects.
In short, I know nothing about the fluorine in the water, but just telling me there is a halogen in it that is poisonous in its pure form says absolutely nothing. Sodium, in its pure form, explodes violently if you expose it to water. Chlorine, in its pure form, is a gas that will put a hefty burn on your lungs and respritory system if you were unfortunate enough to breath it. But salt, sodium-chloride makes everything delicious.
Also, there's also probably trace amounts of Ecoli in the water, but that doesn't kill you either.