Fluorine is a highly toxic green gas that is the main ingredient in non-stick teflon coatings. In ep 28 of Elemental, Prof Allan Blackman from AUT, says that fluorine has very different properties from fluoride.

Fluorine has many nasty traits - it is a deadly poisonous gas that is so reactive that it will burn flesh.

On the other hand, fluorine (Fl, atomic number 9) is a vital trace element in the human body and a key ingredient in many pharmaceuticals.

It is commonly found in kitchens, in non-stick Teflon coatings. Curiously, Teflon was discovered accidentally.

Fluorine is one of the chemicals in 1080, or sodium fluoroacetate, which is a naturally occurring compound that has become a key pest control tool in New Zealand, used to kill rats and stoats on conservation land.

Professor Allan Blackman from AUT is at pains to point out that fluorine is not the same as fluoride. Fluorine is an element while fluoride, used in civic water supplies and toothpaste to help prevent dental cavities, is an ion with very different properties.

Go to this episode on rnz.co.nz for more details