Fluorides

Fluorides are chemical compounds that contain fluorine in the form of the fluoride ion (F−) or fluorine bonded to a metal as a fluoride salt. The fluoride ion is characteristic of many inorganic salts, such as sodium fluoride (NaF) and calcium fluoride (CaF2). Hydrogen fluoride (HF) is a volatile fluoride compound of hydrogen and fluorine. Fluorides occur naturally in minerals and groundwater and have a wide range of industrial uses.

Natural occurrence and production: The mineral fluorite (CaF2) is the principal source of fluoride in ore and is a common fluorine-bearing mineral. Industrially, fluorides are produced by mining and processing fluorite or by reactions that create fluoride salts. In aluminum production, fluoride-containing compounds such as cryolite (Na3AlF6) are used as a flux. Hydrofluoric acid is produced by various fluorination processes and serves as a precursor to many fluoride-containing materials.

Uses: Fluorides are widely used to protect teeth from decay; fluoride ions are added to drinking water and incorporated into toothpastes and mouthwashes. Fluoride salts are used as fluxes in metallurgy, in the production of aluminum, glass and ceramics, and in various chemical syntheses. They also feature in electronics, optics, and certain manufacturing processes.

Health and safety: In low concentrations, fluoride helps reduce dental caries. At higher exposure, fluoride can cause dental fluorosis in children and skeletal fluorosis with long-term ingestion. Acute fluoride salts are toxic, and hydrogen fluoride is highly corrosive and hazardous to skin and respiration. Environmental considerations include potential fluoride releases from industrial processes and the need for controls to prevent ecological effects. Regulation often targets drinking-water fluoride levels, occupational exposure, and permissible emissions.