Re: worries about fluoridated water interfering with our precious bodily lithium, because periodic table.
This is a fine example of the essential hubris of conspiracist thinking: assuming that high school chemistry lets you draw strong conclusions about neurochemistry. It's almost Dunning-Kruger in reverse: an overconfidence so ridiculous that it creates incompetence.
It's worse than that, SOT. This CAN be debunked using High School chemistry. You probably tried and succeeded to purge this from your data banks to make room for physics
, but I had to teach this stuff long after it was ever relevant to my research.
Any decent HS or Freshman university-level chemistry course should talk about solubility constants and equilibria. So, the periodic chart sorta, kinda tells you what will bind to what in solution, but not at what strength. Lots of stuff goes into figuring
that out, not least of which is the interaction between solute and solvent. One can predict that calcium ions and carbonate ions will come out of solution at some point, but without studying the thermodynamics of water clusters around carbonate ions and the calcium carbonate precipitate, it's impossible to predict that calcium carbonate is
less soluble in hot water than in cold (the opposite of most other salts), which is why we had to de-scale my hot water heater twice a year when I was growing up.
Using this little bit of very, very basic chemistry, we go looking for the equilibrium dissociation constant of Lithium Fluoride, which tells us, with the use of a little basic math, at what concentration that lithium is going to combine with fluoride in solution and stay combined.
That constant is 3.8 x 10[SUP]-3[/SUP].
We will also need the concentrations of fluoride ion in water (assuming it all gets into the blood, which is approximately true). That is 1 ppm, or
5.26 x 10[SUP]-5[/SUP]M. We'll also need the lithium ion concentrations, which
max out at 1.58 x 10[SUP]-3[/SUP] M, but are usually half to one tenth that. But let's go with the max to give the benefit of the doubt. We then compare the
reaction quotient (in this case, simply the product of the two ionic concentrations) of 8.31 x 10[SUP]-7 [/SUP]with the equilibrium constant of 3.8 x 10[SUP]-3[/SUP]. You can easily see that the reaction quotient is far, far below the equilibrium constant, and therefore no precipitation of LiF would occur at physiologic concentrations. The real world is a bit more complicated than that due to the blood's buffer system, but there is no common ion effect with the blood, and the actual physiologically available fluoride concentration is less than that of drinking water, so the whole idea of fluoride having an impact on physiologic lithium is still mathematically silly, and easily provably so by some HS chemistry.
This does not, of course, mean that fluoride is beneficial at all doses. The difference between a nutrient or medicine and a poison is always the dose. The anti-fluoridation types like to talk about studies done at higher concentrations than are achieved in normal enhanced drinking water. In Sri Lanka, for example, it's been shown that high concentrations of natural fluoride in drinking water combined with high concentrations of calcium,
contribute to kidney disease. The toxic effects of fluoride usually manifest themselves at concentrations of 5 ppm or greater, which is 5 times the limit of additive fluoride in the US.