Fluoride in Tea
At some point devilfish was interested in my statements that tea contains fluoride. Here's an abstract of a paper from Chulalongkorn University entitled Fluoride in Black Tea. (Note that for a quick counter, danopato will argue that even if this is true, the fluoride is probably not bio-available anyway.)

Contrast this 196 micrograms per bag of tea with a statement from some Canadian Governmental FAQ "The Canadian limit is 1500 micrograms per litre.". To be fair, the abstract of that paper (which I wasn't able to find a copy of) only cited the content of the tea in the tea bag, not how much ends up in your tea.

However, I found a better paper. (z00t!) Fluoride Levels in Hair of Exposed and Unexposed Populations in Poland which has tables that give numbers of micrograms/gram of fluoride in teas and even looks at the strength and quantity of the consumed tea.

"Table 2 presents mean fluoride values in hair in relation to declared nutrition and hygiene habits. Statistical analysis showed no correlation between the concentration of fluoride in hair and the intake of fish, kind and strength of tea and kind of toothpaste used. No significant differences were found between hair samples from people drinking tea; however, the values obtained for people who declared that they do not drink tea at all were substantially lower."

Given their data you really have two options: either A) humans are weird and there's some threshold to our tea absorbtion, or B) there's some correlating personality quirk in people who don't like tea and people who don't participate in high-fluoride activities. However, after actually looking at the data, I'm going to say the real answer lies in option #3: the people who wrote this paper are _really_ bad at statistics and the reviewers should have asked them to get more data. They have almost 200 people who drank 1-2 glasses of tea per day and almost 200 people who drank 3-4 glasses of tea per day and they are comparing this to _a whole 9 people_ who didn't drink tea. I'm sorry... you can't tell much at all from this. The average fluoride concentration of people who don't drink tea is almost half that of both people who use _and don't use_ fluoridated toothpaste. This data has a serious case of Simpson's Paradox.

So really, while I think I've shown my point that tea contains fluoride, it seems like we've also proved danopato's point that it doesn't matter. _However_, I'm going to throw in a few "What if?" theories to show that we really don't have enough data yet:

If options A _and_ B from the previous paragraph are both true, then the data in this chart is consistent. If you use fluoridated toothpaste or drink tea or eat fish, you're fucked and have around 2 micrograms of fluoride presenting. However, if you're truly paranoid, paranoid enough to not drink tea, paranoid enough to use non-fluoridated toothpaste, you might also be paranoid enough to avoid fish (which... apparently?!? is a source of fluoride?...). And, if you avoid all three of those, you will actually make a dent in your daily amount of fluoride.

However, my only sample for someone that paranoid is me, and I had never heard of the fish thing (not that a sample size of 1 is meaningful, hehe). That might not be relevant, however, as we could include a variable C) fish could have nothing to do with it. In that case, the truth is being hidden by the statistical error. It would be interesting to see if the non-tea drinkers were, in fact, in the non-fluoridated toothpaste category. That would clear a lot of this debate up.

Although, even as I write that paragraph, I realize that frankly I don't feel that toothpaste _should_ correlate with the amount of fluoride found in hair. Toothpaste is a non-systemic source of fluoride. The goal is to apply fluoride to your teeth and, without eating the toothpaste, rinse it out along with whatever you dislodged by brushing. Tea, however, _is_ systemic. (As a side note, the flipside of this shows that, even if fluoride was good for your teeth, taking fluoride suppliment pills, which many people were subjected to as youths, _wouldn't help your teeth_.) So really, if just A and C were true then we'd have a significant effect.

Regardless, I still hate the taste of tea (the main reason I don't drink it), so this doesn't end up affecting me much.

[Edit: replaced an occurance of 'fluoride' with 'tea']