Water Fluoridation

I notice neither that Wikipedia page nor the general water fluoridation page cover water fluoridation's alleged effect on IQ, although that's the main recent claim I've seen conspiracy theorists make about it. (My impression, based on a desultory skim through a few of the studies they refer to: they're wrongly inferring causality from fairly weak observational studies that compare people in different regions with different levels of fluoride in the drinking water. These studies normally take place in less developed nations like India & China where the water is more likely to have naturally high levels of fluoride — often more than is added in the US — and other toxic chemicals that could readily confound the results.)

There are many large scientific studies there to show that drinking fluoridated water has no positive effect on cavity reduction and to show that it causes cancer, thyroid damage, broken hips from brittle bones, lowered IQ and other health problems.

Could you link to them?

And now I'm going to brush my teeth....

If it actually affects my brain in a negative way, I would really like to know about it, so VOI is high.

In order to determine the VOI, you need a path from the information to a change in action, with a probability that you'll act differently and an expected value if you do. Both of these are small; the evidence seems to indicate that fluoride is okay, and even if fluoride does affect your brain negatively, the effect size would have to be very small to have escaped detection, and it would have to be weighed against the additional expense of drinking bottled water. (And yes, very-minor brain damage and money are fungible, since you money can buy books and classes and free time and intelligence-enhancing drugs.)

You would have to do more than that; for example, you would have to avoid any toothpastes, obviously, but less obviously you would have to completely cut out tea and some other plants which naturally contain high levels of fluoride. (Tea would be a real sacrifice for me.)

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 actually a chance we are not adding enough, due to some stupid appearance concerns driven by fake teeth and photoshopped advertising.

I'm not even sure any more that fluorine even could have any effect on iodine uptake. There's chlorine and bromine between iodine and fluorine, and we got a lot of chlorine in our bodies.

The cancer issues, well, studying cancer rate empirically is a popular topic for nonsense because there's a lot of co-founding factors yet the highly dubious results that you obtain sound like 'true evidence' to be put against 'theories', whereby the theories are good reasoning based on our knowledge.

For example of one such controversy, small doses of ionizing radiation can be reasonably expected to cause cancer at a rate linearly proportional to doses, due to well understood mechanisms and the radiation not actually diluting at the cellular level. Yet, the folks who are punched in their wallets by this reasoning are funding various nonsense statistical 'studies' (which don't control for co-founding factors as significant as age and smoking) that find positive effects of low doses of radiation, never mind complete lack of any remotely plausible mechanism beyond some non-specific stupidity about some anti-cancer defence responses that are presumed to be asleep when you live normal life having lifetime cancer rate of ~40% with mortality rate 20%, primarily from mutations entirely unrelated to radiation. But which would turn on when radiation several times over background would increase the mutation rate by some tiny fraction of a percent (effect of which is not statistically significant unless you got sample sizes in the tens millions, which you never will have).

Because that's a strictly more complicated hypothesis? Also it runs into cognitive dissonance and issues of belief overkill/confirmation bias?

http://www.youtube.com/watch?v=N1KvgtEnABY

A truly brilliant movie, with many insightful comments on decision theory and Cold War politics. Absolutely everyone should watch it.