Fluoride

1. What are fluorides?

• 1.1 Which fluorides are most relevant?
• 1.2 What are fluorides used for in industry?

1.1 Which fluorides are most relevant?

The source document for this Digest states:

This document focuses on environmental exposure to fluoride derived mostly from inorganic sources and its effects on humans, animals and other biota. Data on hydrogen fluoride, calcium fluoride, sodium fluoride, sulfur hexafluoride and silicofluorides are covered, as these compounds are considered to be the most relevant of the inorganic fluorides on the basis of quantities released to the environment, environmental concentrations and toxicological effects on living organisms."

Source & ©: IPCS "Environmental Health Criteria for Fluorides", (EHC 227), 
Summary of the Report, Chapter 1: Summary and Conclusions 

For more information, see the full IPCs document:
Chapter 2: Identity, Physical and Chemical Properties, and Analytical Methods 

1.2 What are fluorides used for in industry?

The source document for this Digest states:

Hydrogen fluoride (HF) is a colourless, pungent liquid or gas that is highly soluble in organic solvents and in water, in which it forms hydrofluoric acid. Calcium fluoride (CaF₂) is a colourless solid that is relatively insoluble in water and dilute acids and bases. Sodium fluoride (NaF) is a colourless to white solid that is moderately soluble in water. Sulfur hexafluoride (SF₆) is a colourless, odourless, inert gas that is slightly soluble in water and readily soluble in ethanol and bases.

The most common procedure used to quantify free fluoride anion is the fluoride ion-selective electrode. Microdiffusion techniques are considered to be the most accurate methods of sample preparation (i.e., liberation of free ionic fluoride from organic and inorganic complexes)."

"Hydrogen fluoride is an important industrial compound that is used mainly in the production of synthetic cryolite (Na₃AlF₆), aluminium fluoride (AlF₃), motor gasoline alkylates and chlorofluorocarbons, with an annual world consumption in excess of 1 million tonnes. It is also used in etching semiconductor devices, cleaning and etching glass, cleaning brick and aluminium and tanning leather, as well as in commercial rust removers. Calcium fluoride is used as a flux in steel, glass and enamel production, as the raw material for the production of hydrofluoric acid and anhydrous hydrogen fluoride, and as an electrolyte in aluminium production. Sodium fluoride is used in the controlled fluoridation of drinking-water, as a preservative in glues, in glass and enamel production, as a flux in steel and aluminium production, as an insecticide and as a wood preservative. Sulfur hexafluoride is used extensively in various electronic components and in the production of magnesium and aluminium. Fluorosilicic acid (H₂SiF₆) and sodium hexafluorosilicate (Na₂SiF₆) are used for the fluoridation of drinking-water supplies.

Source & ©: IPCS "Environmental Health Criteria for Fluorides", (EHC 227), 
Summary of the Report, Chapter 1 Sections 1.1: Identity, physical and chemical properties
and analytical methods and 1.2: Sources of human nd environmental exposure 

For more information, see the full IPCs document:
Chapter 2: Identity, Physical and Chemical Properties, and Analytical Methods 
Section 3.2.1: Production and use