Hydrogen Fluoride  

What is hydrogen fluoride?

Hydrogen fluoride is a colorless gas comprised of the elements hydrogen and fluorine. It dissolves in water to make hydrofluoric acid. In high concentrations, both hydrogen fluoride and hydrofluoric acid are very corrosive substances.

A significant amount of naturally occurring hydrogen fluoride is released to the air by volcanos both continuously and during eruptions. Weathering of fluoride-containing rocks is an important natural source of this mineral in soil, sediment, and groundwater. In the western U.S., rocks and soils naturally have higher than average fluoride concentrations, so more fluoride is present in that region’s groundwater.

Manmade releases of fluorides to soil are due primarily to the use of fertilizer and the disposal of industrial wastes. Manufacturers of steel, brick, tile, and aluminum release large amounts of hydrogen fluoride. Urban locations usually have higher levels of fluorides in the air. In fact, concentrations in rural areas are usually undetectable.

Hydrogen fluoride and hydrofluoric acid can react with and are neutralized by other substances to form mineral fluorides — materials that are found naturally in soil, oceans, and volcanos.

How is hydrogen fluoride used?

Hydrogen fluoride is an important industrial chemical for fabricating aluminum and stainless steel as well as for etching circuit boards and glass. Hydrogen fluoride is no longer used to produce chlorofluorocarbons (CFCs).

The largest uses of hydrofluoric acid occur during the production of aluminum, steel, petrochemicals, glass, ceramics, resins, solvents, stain removers, and pharmaceuticals.

Do electric utilities release hydrogen fluoride to the environment?

Yes, but EPA estimates that the long-term concentration of hydrogen fluoride in the air around power plants is 100 to 10,000 times BELOW the level that may cause adverse health effects.

Coal contains small amounts of fluoride. As electric utilities burn coal to generate power, naturally occurring fluoride is released. EPA estimates that in 1990 power plants accounted for roughly 12% of all manmade hydrogen fluoride emissions.

How could I be exposed to hydrogen fluoride?

Fluoride is a naturally occurring element, so humans are continuously exposed to small amounts through the air,water, and soil. People living in cities are exposed to higher fluoride levels than those living in rural communities.

Fluoride levels in rivers, streams, and lakes fall between 10 and 30 parts of fluoride per billion parts of water (ppb). Fluoride concentrations in groundwater tend to be higher, and sea water contains slightly more fluoride than fresh water. However, none of these present a health risk.

Air around hazardous waste sites and factories that use or produce hydrogen fluoride, hydrofluoric acid, or fertilizers may have higher than average concentrations of those chemicals.

Hydrofluoric acid is corrosive to skin and eyes. Skin contact with concentrated acid can cause burning and irritation. Inhaling large quantities of hydrofluoric acid or hydrogen fluoride can cause coughing or bronchitis. In extremely rare cases, ingesting large amounts of hydrofluoric acid can be fatal. These levels are much higher than the very small concentrations of hydrogen fluoride that are addressed in this paper.

What does EPA say?

EPA has identified hydrogen fluoride as a hazardous substance, although it rarely occurs in concentrations that are of serious concern to human health. The Agency recommends that the amount of fluoride contained in drinking water not exceed 2,000 ppb. Actual concentrations in drinking water are much lower than this guideline.

Where can I get more information?

• Electric Power Research Institute, 3412 Hillview Ave., P.O. Box 10412, Palo Alto, California 94303; phone (650)855-2000.
  
  
• Background Report, AP-42 Section 5.8, Hydrofluoric Acid, U.S. Environmental Protection Agency, Office of Air Quality Planning and Standards, 1998.
  
  
• EPA Office of Compliance Sector Notebook Project: Profile of the Fossil Fuel Electric Power Generation Industry, U.S. Environmental Protection Agency, Office of Enforcement and Compliance Assurance, 1997.
  
  
• Study of Hazardous Air Pollutant Emissions from Electric Utility Steam Generating Units — Final Report to Congress, Volume 1 and 2, U.S. Environmental Protection Agency, Office of Air Quality Planning and Standards, 1998.
  
  
• Toxicological Profile for Fluorides, Hydrogen Fluoride and Fluorine, U.S. Department of Health and Human Services, Public Health Service, Agency for Toxic Substance and Disease Registry, 1993.