The appeal to nature here isn't just a logical fallacy, it's a particularly bad heuristic in this case: if you ever find yourself actually stuck with nothing but "natural water", then for the sake of your life make sure not to drink it until after you hit it with iodine tablets, give it days of UV exposure, pass it through a microfilter, or do something to make it safe first.
That's all about microorganisms, though; I hadn't heard of any real dangers from tap-water levels of fluoride. Even potential inhibition of iodine uptake is news to me. It's always possible there are extremely subtle effects; look at the correlations between groundwater lithium (in tiny tiny concentrations!) and suicide/violence/addiction rates in those Japan and Texas studies. But AFAIK the only likely effect we know of is still the strong correlation between drinking fluoridated water and not having your teeth rot away.
Yep. One simple way to make water safe from micro-organisms is to boil it. The few that survive are no big deal, and it's no worse than all the food you eat anyway.
With regards to natural, the thing is that we didn't just decide to add fluorine to water everywhere. It's added to water where natural level is too low, and removed where natural level is too high. And the worst that is happening from the level that is considered to be optimal is some instances of minor cosmetic effect on the teeth, which correlates with even fewer cavities. So there is actuall...
I've recently learned about alleged dangers to drinking fluoridated water. Amongst them is increased rate of cancer and lowering of IQ. Interestingly enough, wiki doesn't mention this at all, but searching for it brings up a decent amount of (what look like) reasonable results. I am really curious about this, and want to learn more about this. I was wondering if anyone on LW has already conducted a research literature investigation on this topic, or if you just have tips/advice on what to pay attention to when I read the literature.
Thanks!