In the United States, pretty much everyone is familiar with fluoride. The element fluorine is the lightest halogen and exists as a highly toxic, yellow gas at room temperature. But we know it better in its anionic form, fluoride.
It's in our drinking water and toothpaste, and helps to prevent tooth decay and keep our teeth strong. (But did you know that several countries have chosen to no longer fluoridate their water? The CDC says it's one of the top ten greatest public health achievements. Others have argued that it's a compulsory, mass medication in our drinking water. Thoughts?)
A little too much fluoride in your drinking water (or swallowing too much toothpaste) can cause dental fluorosis, which is harmless but causes cosmetic changes to the enamel in the form of stained and pitted teeth.
Chronic fluorosis, which is from consuming too much fluoride over time, can result in denser but brittle bones, calcified ligaments, stiffness and joint pain.
|The arrows are pointing to excessive calcium deposits on the forearms and spine. Source: NEJM|
And guess what? You can get it from tea, too. Tea plants tend to accumulate fluoride from the soil. See those x-rays up there? They were from a woman who drank >100 tea bags worth of tea every day for 17 years (read here for the New England Journal of Medicine article.)
People who drink a lot of brick tea are at risk, too. What is brick tea? I actually snapped this photo at one of my favorite tea shops, thinking it looked just like an ink stone for Asian calligraphy.
Apparently, this type of tea can be made from older tea plants, and so they accumulate more fluoride than your usual cup of tea.
For more information, check out the CDC page on dental fluorosis and the WHO page on fluorosis due to drinking water. For parents, here's the info page on dental fluorosis by HealthyKids.org.
Have fun brushing your teeth and overthinking the entire process! :D