There has been some confusing results coming from tea-investigations though. I expect those results to be caused by content of Al, Pb and so on, especially from tea produced by our Asian Brown Cloud friends in China. I think Fluoride is very attractive to blame things on in general for some reason, I'm a lot more worried by mercury in fish and lead in tea.
Do you have a a reference to these investigations? Tea naturally has high levels of F and Al, but not Pb, which has to come from contaminated soil.
Mercury certainly is something be concerned about, but fortunately we know which species of long-living predatory fish accumulate mercury: shark, swordfish, king mackerel, tilefish and albacore and blackfin tuna. Those species should be avoided anyway for environmental reasons. I wouldn't be too concerned about the relatively low levels of methylmercury found in other species, as the epidemiology very clearly shows a net benefit from fish eating. Moreover, there's some fascinating research on a particular selenium compound in fish - selenonein - which seems to specifically reduce the toxicity of methymercury. As so often in Nature, the poison comes in a package with its antidote.
For comparison, TJ's toothpaste is 7600mg/L, 7.6mg/mL, or 0.76% fluoride. In terms of fluoride content, 4L tea = 0.25mL toothpaste. A quater milliliter is an amount you might swallow, or be left as a residue after spitting/rinsing. So it could double my exposure, from 2mg daily to 4mg.
This is an insane level of fluoride for sure. I doubt it is representative of most toothpaste availabe in the US. In Europe, there is an upper limit of 1500 mg/L for toothpaste and 500 mg/L for mouthrinse given per law, as those concentrations have been shown effective in clinical trials and pose minimal risk of fluoridosis even if used inappropriately and swallowed. If one typically uses 2 g of fluoridated toothpaste and 10 g of mouthrinse, it would make 8 mg of total fluoride. Given that you inevitably swallow about 10%, you'd be exposed to ~1 mg of fluoride, roughly the same amount you'd get from one cup of black tea made from a bag or from 0.5-1 L of fluoridated water.
The beauty of fluoride in dental health products is that it can act topically where it is most beneficial - on the tooth enamel - and doesn't have to be absorbed systemically in much larger doses to have to same effect (and possible systemic adverse effects).
Edited by timar, 20 May 2015 - 07:46 AM.
