Fluere is the Latin word for flow and provides the root for the name of the element we know as fluorine. One of the common naturally occurring sources of fluorine is the mineral calcium fluoride, also known as fluorspar. It melts when heated and flows readily, hence the relation to 鈥渇luere.鈥� In its elemental form, fluorine is a gas and is highly reactive and dangerous, but it does not occur in nature in this form. However, it can be found widely as the fluoride ion, a stable species. It is in this form that it is found in the human body and is in fact an essential nutrient. Proper growth is inhibited if fluoride is absent. But since fluoride occurs so widely in nature, deficiencies are unheard of. Fluoride is a typical example of a substance that is essential in small doses but is problematic as doses increase and can even be lethal at high doses. One gram will provoke a toxic response and five grams will kill. Unfortunately we have documented evidence of the lethality of large doses of fluoride. In 1943 at an American hospital by accident sodium fluoride was added to scrambled eggs instead of sodium chloride, which of course is salt. 163 patients became ill and 47 died. Fluoride can block the effects of certain enzymes that are critical to life. But to have any such effect intake has to be significantly more than the 0.3 to 3 mg that the average person ingests in a day. This can come from fluoridated water as well as from foods such as poultry, pork, eggs, potatoes, butter, cheese and tea. Tea contains anout 0.4 mg per cup. Seawater contains about 1 ppm of fluoride so fish do accumulate the element. Mackerel, for example, has about 27 ppm. Numerous compounds of fluorine are known. Ofloxacin is a very useful antibiotic, it can cure gonorrhea. There are a number of others in the fluoroquinolone family. Fluorocarbons are used in refrigeration equipment and air conditioners and uranium hexafluoride is needed to separate uranium 235 from uranium 238. Fluoride is also what gives Teflon, polytetrafluoroethylene in chemical terms, its unique properties.
