Fluorine and inorganic compounds (as hydrogen fluoride)
Fluorine is a faint greenish yellow gas with a chlorine gas-like pungent odour. Fluorine is the most reactive element and reacts immediately with other compounds or materials to fluorides or hydrogen fluoride.
At normal temperatures and pressure, hydrogen fluoride occurs as a colourless, non-flammable, highly toxic and irritant gas (liquid hydrogen fluoride boils at 19 0C), but is usually encountered as a solution in water (i.e. hydrofluoric acid) containing up to 70% hydrogen fluoride. Hydrofluoric acid dissolves glass and attacks many metals (releasing flammable hydrogen in the process), minerals and organic substances. Solutions of hydrogen fluoride are kept in plastic containers.
Hydrogen fluoride is too reactive to persist for very long in the environment and is rapidly converted to other fluorides. Fluoride minerals are widespread in the environment and fluoride is a trace component of natural waters.
Hydrogen fluoride has a number of industrial applications, such as the cleaning and etching of glass, semi-conductor manufacture, ceramics manufacture, electroplating, as an intermediate in the chemical industry and in the manufacture of dental prostheses (e.g. tooth crowns etc). The chemical has been used in the home in the US for rust removal but is believed not to be marketed for domestic use in Europe.
High temperature industrial processes are the main man-made source of releases of hydrogen fluoride and other inorganic fluorides to the atmosphere. These processes include coal combustion, primary aluminium smelting, phosphate fertiliser manufacture and glass, brick and tile making. Hydrogen fluoride may also be formed when organic fluorine compounds (e.g. fluorocarbons, fluoropolymers, etc used as aerosol propellants, refrigerants, fire extinguisher chemicals, plastic or rubbers) are exposed to fires. Fire-damaged items that may be contaminated with hydrogen fluoride must therefore be handled with very great care.
Impacts on human health and environment
Excessive exposure to hydrogen fluoride may affect the bone, eye, heart, lung, nose, skin and throat due to its corrosive properties and fluorides formation.
Hydrogen fluoride released into the atmosphere is washed onto the earth's surface in rain and is neutralised to form inorganic fluoride salts. The fluoride ion itself is highly toxic to living organisms. It binds strongly with calcium and magnesium and prevents these essential nutrient elements from carrying out their biochemical functions. This is the basis for the toxicity of inorganic fluorides (see also data on substance 'fluorides').
Hydrogen fluoride emissions can cause damage to plants and be harmful to cattle and other animals.
Hydrogen fluoride (CAS No. 7664-39-3) is a priority substance under Regulation 793/93. The Risk Assessment Report has been completed and can be downloaded from http://ecb.jrc.it/existing-chemicals/.
Emission to air reporting threshold: 5000 kg/year
Data source: European Pollutant Emission Register