Q Is there a source of fluoride I don't know about?
Drinking water. Fluoride naturally occurs in water but most cities in America add it in as well. Typically the level of fluoride is kept around 1 part per million. More is needed in the warm months due to evaporation and less is needed in cooler months. Boiling water, especially for coffee, can lead to fluoride loss in your water. For more information, Dr. Freeman wrote an article about how fluoride prevents cavities.